fs/proc/base.c

   1 /*
   2  *  linux/fs/proc/base.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  proc base directory handling functions
   7  *
   8  *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
   9  *  Instead of using magical inumbers to determine the kind of object
  10  *  we allocate and fill in-core inodes upon lookup. They don't even
  11  *  go into icache. We cache the reference to task_struct upon lookup too.
  12  *  Eventually it should become a filesystem in its own. We don't use the
  13  *  rest of procfs anymore.
  14  *
  15  *
  16  *  Changelog:
  17  *  17-Jan-2005
  18  *  Allan Bezerra
  19  *  Bruna Moreira <[email protected]>
  20  *  Edjard Mota <[email protected]>
  21  *  Ilias Biris <[email protected]>
  22  *  Mauricio Lin <[email protected]>
  23  *
  24  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
  25  *
  26  *  A new process specific entry (smaps) included in /proc. It shows the
  27  *  size of rss for each memory area. The maps entry lacks information
  28  *  about physical memory size (rss) for each mapped file, i.e.,
  29  *  rss information for executables and library files.
  30  *  This additional information is useful for any tools that need to know
  31  *  about physical memory consumption for a process specific library.
  32  *
  33  *  Changelog:
  34  *  21-Feb-2005
  35  *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
  36  *  Pud inclusion in the page table walking.
  37  *
  38  *  ChangeLog:
  39  *  10-Mar-2005
  40  *  10LE Instituto Nokia de Tecnologia - INdT:
  41  *  A better way to walks through the page table as suggested by Hugh Dickins.
  42  *
  43  *  Simo Piiroinen <[email protected]>:
  44  *  Smaps information related to shared, private, clean and dirty pages.
  45  *
  46  *  Paul Mundt <[email protected]>:
  47  *  Overall revision about smaps.
  48  */
  49
  50 #include <linux/uaccess.h>
  51
  52 #include <linux/errno.h>
  53 #include <linux/time.h>
  54 #include <linux/proc_fs.h>
  55 #include <linux/stat.h>
  56 #include <linux/task_io_accounting_ops.h>
  57 #include <linux/init.h>
  58 #include <linux/capability.h>
  59 #include <linux/file.h>
  60 #include <linux/fdtable.h>
  61 #include <linux/string.h>
  62 #include <linux/seq_file.h>
  63 #include <linux/namei.h>
  64 #include <linux/mnt_namespace.h>
  65 #include <linux/mm.h>
  66 #include <linux/swap.h>
  67 #include <linux/rcupdate.h>
  68 #include <linux/kallsyms.h>
  69 #include <linux/stacktrace.h>
  70 #include <linux/resource.h>
  71 #include <linux/module.h>
  72 #include <linux/mount.h>
  73 #include <linux/security.h>
  74 #include <linux/ptrace.h>
  75 #include <linux/tracehook.h>
  76 #include <linux/printk.h>
  77 #include <linux/cgroup.h>
  78 #include <linux/cpuset.h>
  79 #include <linux/audit.h>
  80 #include <linux/poll.h>
  81 #include <linux/nsproxy.h>
  82 #include <linux/oom.h>
  83 #include <linux/elf.h>
  84 #include <linux/pid_namespace.h>
  85 #include <linux/user_namespace.h>
  86 #include <linux/fs_struct.h>
  87 #include <linux/slab.h>
  88 #include <linux/sched/autogroup.h>
  89 #include <linux/sched/mm.h>
  90 #include <linux/sched/coredump.h>
  91 #include <linux/sched/debug.h>
  92 #include <linux/sched/stat.h>
  93 #include <linux/flex_array.h>
  94 #include <linux/posix-timers.h>
  95 #ifdef CONFIG_HARDWALL
  96 #include <asm/hardwall.h>
  97 #endif
  98 #include <trace/events/oom.h>
  99 #include "internal.h"
 100 #include "fd.h"
 101
 102 /* NOTE:
 103  *      Implementing inode permission operations in /proc is almost
 104  *      certainly an error.  Permission checks need to happen during
 105  *      each system call not at open time.  The reason is that most of
 106  *      what we wish to check for permissions in /proc varies at runtime.
 107  *
 108  *      The classic example of a problem is opening file descriptors
 109  *      in /proc for a task before it execs a suid executable.
 110  */
 111
 112 static u8 nlink_tid;
 113 static u8 nlink_tgid;
 114
 115 struct pid_entry {
 116         const char *name;
 117         unsigned int len;
 118         umode_t mode;
 119         const struct inode_operations *iop;
 120         const struct file_operations *fop;
 121         union proc_op op;
 122 };
 123
 124 #define NOD(NAME, MODE, IOP, FOP, OP) {                 \
 125         .name = (NAME),                                 \
 126         .len  = sizeof(NAME) - 1,                       \
 127         .mode = MODE,                                   \
 128         .iop  = IOP,                                    \
 129         .fop  = FOP,                                    \
 130         .op   = OP,                                     \
 131 }
 132
 133 #define DIR(NAME, MODE, iops, fops)     \
 134         NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} )
 135 #define LNK(NAME, get_link)                                     \
 136         NOD(NAME, (S_IFLNK|S_IRWXUGO),                          \
 137                 &proc_pid_link_inode_operations, NULL,          \
 138                 { .proc_get_link = get_link } )
 139 #define REG(NAME, MODE, fops)                           \
 140         NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {})
 141 #define ONE(NAME, MODE, show)                           \
 142         NOD(NAME, (S_IFREG|(MODE)),                     \
 143                 NULL, &proc_single_file_operations,     \
 144                 { .proc_show = show } )
 145
 146 /*
 147  * Count the number of hardlinks for the pid_entry table, excluding the .
 148  * and .. links.
 149  */
 150 static unsigned int __init pid_entry_nlink(const struct pid_entry *entries,
 151         unsigned int n)
 152 {
 153         unsigned int i;
 154         unsigned int count;
 155
 156         count = 2;
 157         for (i = 0; i < n; ++i) {
 158                 if (S_ISDIR(entries[i].mode))
 159                         ++count;
 160         }
 161
 162         return count;
 163 }
 164
 165 static int get_task_root(struct task_struct *task, struct path *root)
 166 {
 167         int result = -ENOENT;
 168
 169         task_lock(task);
 170         if (task->fs) {
 171                 get_fs_root(task->fs, root);
 172                 result = 0;
 173         }
 174         task_unlock(task);
 175         return result;
 176 }
 177
 178 static int proc_cwd_link(struct dentry *dentry, struct path *path)
 179 {
 180         struct task_struct *task = get_proc_task(d_inode(dentry));
 181         int result = -ENOENT;
 182
 183         if (task) {
 184                 task_lock(task);
 185                 if (task->fs) {
 186                         get_fs_pwd(task->fs, path);
 187                         result = 0;
 188                 }
 189                 task_unlock(task);
 190                 put_task_struct(task);
 191         }
 192         return result;
 193 }
 194
 195 static int proc_root_link(struct dentry *dentry, struct path *path)
 196 {
 197         struct task_struct *task = get_proc_task(d_inode(dentry));
 198         int result = -ENOENT;
 199
 200         if (task) {
 201                 result = get_task_root(task, path);
 202                 put_task_struct(task);
 203         }
 204         return result;
 205 }
 206
 207 static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
 208                                      size_t _count, loff_t *pos)
 209 {
 210         struct task_struct *tsk;
 211         struct mm_struct *mm;
 212         char *page;
 213         unsigned long count = _count;
 214         unsigned long arg_start, arg_end, env_start, env_end;
 215         unsigned long len1, len2, len;
 216         unsigned long p;
 217         char c;
 218         ssize_t rv;
 219
 220         BUG_ON(*pos < 0);
 221
 222         tsk = get_proc_task(file_inode(file));
 223         if (!tsk)
 224                 return -ESRCH;
 225         mm = get_task_mm(tsk);
 226         put_task_struct(tsk);
 227         if (!mm)
 228                 return 0;
 229         /* Check if process spawned far enough to have cmdline. */
 230         if (!mm->env_end) {
 231                 rv = 0;
 232                 goto out_mmput;
 233         }
 234
 235         page = (char *)__get_free_page(GFP_TEMPORARY);
 236         if (!page) {
 237                 rv = -ENOMEM;
 238                 goto out_mmput;
 239         }
 240
 241         down_read(&mm->mmap_sem);
 242         arg_start = mm->arg_start;
 243         arg_end = mm->arg_end;
 244         env_start = mm->env_start;
 245         env_end = mm->env_end;
 246         up_read(&mm->mmap_sem);
 247
 248         BUG_ON(arg_start > arg_end);
 249         BUG_ON(env_start > env_end);
 250
 251         len1 = arg_end - arg_start;
 252         len2 = env_end - env_start;
 253
 254         /* Empty ARGV. */
 255         if (len1 == 0) {
 256                 rv = 0;
 257                 goto out_free_page;
 258         }
 259         /*
 260          * Inherently racy -- command line shares address space
 261          * with code and data.
 262          */
 263         rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
 264         if (rv <= 0)
 265                 goto out_free_page;
 266
 267         rv = 0;
 268
 269         if (c == '\0') {
 270                 /* Command line (set of strings) occupies whole ARGV. */
 271                 if (len1 <= *pos)
 272                         goto out_free_page;
 273
 274                 p = arg_start + *pos;
 275                 len = len1 - *pos;
 276                 while (count > 0 && len > 0) {
 277                         unsigned int _count;
 278                         int nr_read;
 279
 280                         _count = min3(count, len, PAGE_SIZE);
 281                         nr_read = access_remote_vm(mm, p, page, _count, 0);
 282                         if (nr_read < 0)
 283                                 rv = nr_read;
 284                         if (nr_read <= 0)
 285                                 goto out_free_page;
 286
 287                         if (copy_to_user(buf, page, nr_read)) {
 288                                 rv = -EFAULT;
 289                                 goto out_free_page;
 290                         }
 291
 292                         p       += nr_read;
 293                         len     -= nr_read;
 294                         buf     += nr_read;
 295                         count   -= nr_read;
 296                         rv      += nr_read;
 297                 }
 298         } else {
 299                 /*
 300                  * Command line (1 string) occupies ARGV and
 301                  * extends into ENVP.
 302                  */
 303                 struct {
 304                         unsigned long p;
 305                         unsigned long len;
 306                 } cmdline[2] = {
 307                         { .p = arg_start, .len = len1 },
 308                         { .p = env_start, .len = len2 },
 309                 };
 310                 loff_t pos1 = *pos;
 311                 unsigned int i;
 312
 313                 i = 0;
 314                 while (i < 2 && pos1 >= cmdline[i].len) {
 315                         pos1 -= cmdline[i].len;
 316                         i++;
 317                 }
 318                 while (i < 2) {
 319                         p = cmdline[i].p + pos1;
 320                         len = cmdline[i].len - pos1;
 321                         while (count > 0 && len > 0) {
 322                                 unsigned int _count, l;
 323                                 int nr_read;
 324                                 bool final;
 325
 326                                 _count = min3(count, len, PAGE_SIZE);
 327                                 nr_read = access_remote_vm(mm, p, page, _count, 0);
 328                                 if (nr_read < 0)
 329                                         rv = nr_read;
 330                                 if (nr_read <= 0)
 331                                         goto out_free_page;
 332
 333                                 /*
 334                                  * Command line can be shorter than whole ARGV
 335                                  * even if last "marker" byte says it is not.
 336                                  */
 337                                 final = false;
 338                                 l = strnlen(page, nr_read);
 339                                 if (l < nr_read) {
 340                                         nr_read = l;
 341                                         final = true;
 342                                 }
 343
 344                                 if (copy_to_user(buf, page, nr_read)) {
 345                                         rv = -EFAULT;
 346                                         goto out_free_page;
 347                                 }
 348
 349                                 p       += nr_read;
 350                                 len     -= nr_read;
 351                                 buf     += nr_read;
 352                                 count   -= nr_read;
 353                                 rv      += nr_read;
 354
 355                                 if (final)
 356                                         goto out_free_page;
 357                         }
 358
 359                         /* Only first chunk can be read partially. */
 360                         pos1 = 0;
 361                         i++;
 362                 }
 363         }
 364
 365 out_free_page:
 366         free_page((unsigned long)page);
 367 out_mmput:
 368         mmput(mm);
 369         if (rv > 0)
 370                 *pos += rv;
 371         return rv;
 372 }
 373
 374 static const struct file_operations proc_pid_cmdline_ops = {
 375         .read   = proc_pid_cmdline_read,
 376         .llseek = generic_file_llseek,
 377 };
 378
 379 #ifdef CONFIG_KALLSYMS
 380 /*
 381  * Provides a wchan file via kallsyms in a proper one-value-per-file format.
 382  * Returns the resolved symbol.  If that fails, simply return the address.
 383  */
 384 static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
 385                           struct pid *pid, struct task_struct *task)
 386 {
 387         unsigned long wchan;
 388         char symname[KSYM_NAME_LEN];
 389
 390         wchan = get_wchan(task);
 391
 392         if (wchan && ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)
 393                         && !lookup_symbol_name(wchan, symname))
 394                 seq_printf(m, "%s", symname);
 395         else
 396                 seq_putc(m, '0');
 397
 398         return 0;
 399 }
 400 #endif /* CONFIG_KALLSYMS */
 401
 402 static int lock_trace(struct task_struct *task)
 403 {
 404         int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
 405         if (err)
 406                 return err;
 407         if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
 408                 mutex_unlock(&task->signal->cred_guard_mutex);
 409                 return -EPERM;
 410         }
 411         return 0;
 412 }
 413
 414 static void unlock_trace(struct task_struct *task)
 415 {
 416         mutex_unlock(&task->signal->cred_guard_mutex);
 417 }
 418
 419 #ifdef CONFIG_STACKTRACE
 420
 421 #define MAX_STACK_TRACE_DEPTH   64
 422
 423 static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
 424                           struct pid *pid, struct task_struct *task)
 425 {
 426         struct stack_trace trace;
 427         unsigned long *entries;
 428         int err;
 429         int i;
 430
 431         entries = kmalloc(MAX_STACK_TRACE_DEPTH * sizeof(*entries), GFP_KERNEL);
 432         if (!entries)
 433                 return -ENOMEM;
 434
 435         trace.nr_entries        = 0;
 436         trace.max_entries       = MAX_STACK_TRACE_DEPTH;
 437         trace.entries           = entries;
 438         trace.skip              = 0;
 439
 440         err = lock_trace(task);
 441         if (!err) {
 442                 save_stack_trace_tsk(task, &trace);
 443
 444                 for (i = 0; i < trace.nr_entries; i++) {
 445                         seq_printf(m, "[<%pK>] %pB\n",
 446                                    (void *)entries[i], (void *)entries[i]);
 447                 }
 448                 unlock_trace(task);
 449         }
 450         kfree(entries);
 451
 452         return err;
 453 }
 454 #endif
 455
 456 #ifdef CONFIG_SCHED_INFO
 457 /*
 458  * Provides /proc/PID/schedstat
 459  */
 460 static int proc_pid_schedstat(struct seq_file *m, struct pid_namespace *ns,
 461                               struct pid *pid, struct task_struct *task)
 462 {
 463         if (unlikely(!sched_info_on()))
 464                 seq_printf(m, "0 0 0\n");
 465         else
 466                 seq_printf(m, "%llu %llu %lu\n",
 467                    (unsigned long long)task->se.sum_exec_runtime,
 468                    (unsigned long long)task->sched_info.run_delay,
 469                    task->sched_info.pcount);
 470
 471         return 0;
 472 }
 473 #endif
 474
 475 #ifdef CONFIG_LATENCYTOP
 476 static int lstats_show_proc(struct seq_file *m, void *v)
 477 {
 478         int i;
 479         struct inode *inode = m->private;
 480         struct task_struct *task = get_proc_task(inode);
 481
 482         if (!task)
 483                 return -ESRCH;
 484         seq_puts(m, "Latency Top version : v0.1\n");
 485         for (i = 0; i < 32; i++) {
 486                 struct latency_record *lr = &task->latency_record[i];
 487                 if (lr->backtrace[0]) {
 488                         int q;
 489                         seq_printf(m, "%i %li %li",
 490                                    lr->count, lr->time, lr->max);
 491                         for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
 492                                 unsigned long bt = lr->backtrace[q];
 493                                 if (!bt)
 494                                         break;
 495                                 if (bt == ULONG_MAX)
 496                                         break;
 497                                 seq_printf(m, " %ps", (void *)bt);
 498                         }
 499                         seq_putc(m, '\n');
 500                 }
 501
 502         }
 503         put_task_struct(task);
 504         return 0;
 505 }
 506
 507 static int lstats_open(struct inode *inode, struct file *file)
 508 {
 509         return single_open(file, lstats_show_proc, inode);
 510 }
 511
 512 static ssize_t lstats_write(struct file *file, const char __user *buf,
 513                             size_t count, loff_t *offs)
 514 {
 515         struct task_struct *task = get_proc_task(file_inode(file));
 516
 517         if (!task)
 518                 return -ESRCH;
 519         clear_all_latency_tracing(task);
 520         put_task_struct(task);
 521
 522         return count;
 523 }
 524
 525 static const struct file_operations proc_lstats_operations = {
 526         .open           = lstats_open,
 527         .read           = seq_read,
 528         .write          = lstats_write,
 529         .llseek         = seq_lseek,
 530         .release        = single_release,
 531 };
 532
 533 #endif
 534
 535 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
 536                           struct pid *pid, struct task_struct *task)
 537 {
 538         unsigned long totalpages = totalram_pages + total_swap_pages;
 539         unsigned long points = 0;
 540
 541         points = oom_badness(task, NULL, NULL, totalpages) *
 542                                         1000 / totalpages;
 543         seq_printf(m, "%lu\n", points);
 544
 545         return 0;
 546 }
 547
 548 struct limit_names {
 549         const char *name;
 550         const char *unit;
 551 };
 552
 553 static const struct limit_names lnames[RLIM_NLIMITS] = {
 554         [RLIMIT_CPU] = {"Max cpu time", "seconds"},
 555         [RLIMIT_FSIZE] = {"Max file size", "bytes"},
 556         [RLIMIT_DATA] = {"Max data size", "bytes"},
 557         [RLIMIT_STACK] = {"Max stack size", "bytes"},
 558         [RLIMIT_CORE] = {"Max core file size", "bytes"},
 559         [RLIMIT_RSS] = {"Max resident set", "bytes"},
 560         [RLIMIT_NPROC] = {"Max processes", "processes"},
 561         [RLIMIT_NOFILE] = {"Max open files", "files"},
 562         [RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
 563         [RLIMIT_AS] = {"Max address space", "bytes"},
 564         [RLIMIT_LOCKS] = {"Max file locks", "locks"},
 565         [RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
 566         [RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
 567         [RLIMIT_NICE] = {"Max nice priority", NULL},
 568         [RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
 569         [RLIMIT_RTTIME] = {"Max realtime timeout", "us"},
 570 };
 571
 572 /* Display limits for a process */
 573 static int proc_pid_limits(struct seq_file *m, struct pid_namespace *ns,
 574                            struct pid *pid, struct task_struct *task)
 575 {
 576         unsigned int i;
 577         unsigned long flags;
 578
 579         struct rlimit rlim[RLIM_NLIMITS];
 580
 581         if (!lock_task_sighand(task, &flags))
 582                 return 0;
 583         memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
 584         unlock_task_sighand(task, &flags);
 585
 586         /*
 587          * print the file header
 588          */
 589        seq_printf(m, "%-25s %-20s %-20s %-10s\n",
 590                   "Limit", "Soft Limit", "Hard Limit", "Units");
 591
 592         for (i = 0; i < RLIM_NLIMITS; i++) {
 593                 if (rlim[i].rlim_cur == RLIM_INFINITY)
 594                         seq_printf(m, "%-25s %-20s ",
 595                                    lnames[i].name, "unlimited");
 596                 else
 597                         seq_printf(m, "%-25s %-20lu ",
 598                                    lnames[i].name, rlim[i].rlim_cur);
 599
 600                 if (rlim[i].rlim_max == RLIM_INFINITY)
 601                         seq_printf(m, "%-20s ", "unlimited");
 602                 else
 603                         seq_printf(m, "%-20lu ", rlim[i].rlim_max);
 604
 605                 if (lnames[i].unit)
 606                         seq_printf(m, "%-10s\n", lnames[i].unit);
 607                 else
 608                         seq_putc(m, '\n');
 609         }
 610
 611         return 0;
 612 }
 613
 614 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
 615 static int proc_pid_syscall(struct seq_file *m, struct pid_namespace *ns,
 616                             struct pid *pid, struct task_struct *task)
 617 {
 618         long nr;
 619         unsigned long args[6], sp, pc;
 620         int res;
 621
 622         res = lock_trace(task);
 623         if (res)
 624                 return res;
 625
 626         if (task_current_syscall(task, &nr, args, 6, &sp, &pc))
 627                 seq_puts(m, "running\n");
 628         else if (nr < 0)
 629                 seq_printf(m, "%ld 0x%lx 0x%lx\n", nr, sp, pc);
 630         else
 631                 seq_printf(m,
 632                        "%ld 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
 633                        nr,
 634                        args[0], args[1], args[2], args[3], args[4], args[5],
 635                        sp, pc);
 636         unlock_trace(task);
 637
 638         return 0;
 639 }
 640 #endif /* CONFIG_HAVE_ARCH_TRACEHOOK */
 641
 642 /************************************************************************/
 643 /*                       Here the fs part begins                        */
 644 /************************************************************************/
 645
 646 /* permission checks */
 647 static int proc_fd_access_allowed(struct inode *inode)
 648 {
 649         struct task_struct *task;
 650         int allowed = 0;
 651         /* Allow access to a task's file descriptors if it is us or we
 652          * may use ptrace attach to the process and find out that
 653          * information.
 654          */
 655         task = get_proc_task(inode);
 656         if (task) {
 657                 allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
 658                 put_task_struct(task);
 659         }
 660         return allowed;
 661 }
 662
 663 int proc_setattr(struct dentry *dentry, struct iattr *attr)
 664 {
 665         int error;
 666         struct inode *inode = d_inode(dentry);
 667
 668         if (attr->ia_valid & ATTR_MODE)
 669                 return -EPERM;
 670
 671         error = setattr_prepare(dentry, attr);
 672         if (error)
 673                 return error;
 674
 675         setattr_copy(inode, attr);
 676         mark_inode_dirty(inode);
 677         return 0;
 678 }
 679
 680 /*
 681  * May current process learn task's sched/cmdline info (for hide_pid_min=1)
 682  * or euid/egid (for hide_pid_min=2)?
 683  */
 684 static bool has_pid_permissions(struct pid_namespace *pid,
 685                                  struct task_struct *task,
 686                                  int hide_pid_min)
 687 {
 688         if (pid->hide_pid < hide_pid_min)
 689                 return true;
 690         if (in_group_p(pid->pid_gid))
 691                 return true;
 692         return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
 693 }
 694
 695
 696 static int proc_pid_permission(struct inode *inode, int mask)
 697 {
 698         struct pid_namespace *pid = inode->i_sb->s_fs_info;
 699         struct task_struct *task;
 700         bool has_perms;
 701
 702         task = get_proc_task(inode);
 703         if (!task)
 704                 return -ESRCH;
 705         has_perms = has_pid_permissions(pid, task, HIDEPID_NO_ACCESS);
 706         put_task_struct(task);
 707
 708         if (!has_perms) {
 709                 if (pid->hide_pid == HIDEPID_INVISIBLE) {
 710                         /*
 711                          * Let's make getdents(), stat(), and open()
 712                          * consistent with each other.  If a process
 713                          * may not stat() a file, it shouldn't be seen
 714                          * in procfs at all.
 715                          */
 716                         return -ENOENT;
 717                 }
 718
 719                 return -EPERM;
 720         }
 721         return generic_permission(inode, mask);
 722 }
 723
 724
 725
 726 static const struct inode_operations proc_def_inode_operations = {
 727         .setattr        = proc_setattr,
 728 };
 729
 730 static int proc_single_show(struct seq_file *m, void *v)
 731 {
 732         struct inode *inode = m->private;
 733         struct pid_namespace *ns;
 734         struct pid *pid;
 735         struct task_struct *task;
 736         int ret;
 737
 738         ns = inode->i_sb->s_fs_info;
 739         pid = proc_pid(inode);
 740         task = get_pid_task(pid, PIDTYPE_PID);
 741         if (!task)
 742                 return -ESRCH;
 743
 744         ret = PROC_I(inode)->op.proc_show(m, ns, pid, task);
 745
 746         put_task_struct(task);
 747         return ret;
 748 }
 749
 750 static int proc_single_open(struct inode *inode, struct file *filp)
 751 {
 752         return single_open(filp, proc_single_show, inode);
 753 }
 754
 755 static const struct file_operations proc_single_file_operations = {
 756         .open           = proc_single_open,
 757         .read           = seq_read,
 758         .llseek         = seq_lseek,
 759         .release        = single_release,
 760 };
 761
 762
 763 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
 764 {
 765         struct task_struct *task = get_proc_task(inode);
 766         struct mm_struct *mm = ERR_PTR(-ESRCH);
 767
 768         if (task) {
 769                 mm = mm_access(task, mode | PTRACE_MODE_FSCREDS);
 770                 put_task_struct(task);
 771
 772                 if (!IS_ERR_OR_NULL(mm)) {
 773                         /* ensure this mm_struct can't be freed */
 774                         mmgrab(mm);
 775                         /* but do not pin its memory */
 776                         mmput(mm);
 777                 }
 778         }
 779
 780         return mm;
 781 }
 782
 783 static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
 784 {
 785         struct mm_struct *mm = proc_mem_open(inode, mode);
 786
 787         if (IS_ERR(mm))
 788                 return PTR_ERR(mm);
 789
 790         file->private_data = mm;
 791         return 0;
 792 }
 793
 794 static int mem_open(struct inode *inode, struct file *file)
 795 {
 796         int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH);
 797
 798         /* OK to pass negative loff_t, we can catch out-of-range */
 799         file->f_mode |= FMODE_UNSIGNED_OFFSET;
 800
 801         return ret;
 802 }
 803
 804 static ssize_t mem_rw(struct file *file, char __user *buf,
 805                         size_t count, loff_t *ppos, int write)
 806 {
 807         struct mm_struct *mm = file->private_data;
 808         unsigned long addr = *ppos;
 809         ssize_t copied;
 810         char *page;
 811         unsigned int flags;
 812
 813         if (!mm)
 814                 return 0;
 815
 816         page = (char *)__get_free_page(GFP_TEMPORARY);
 817         if (!page)
 818                 return -ENOMEM;
 819
 820         copied = 0;
 821         if (!mmget_not_zero(mm))
 822                 goto free;
 823
 824         flags = FOLL_FORCE | (write ? FOLL_WRITE : 0);
 825
 826         while (count > 0) {
 827                 int this_len = min_t(int, count, PAGE_SIZE);
 828
 829                 if (write && copy_from_user(page, buf, this_len)) {
 830                         copied = -EFAULT;
 831                         break;
 832                 }
 833
 834                 this_len = access_remote_vm(mm, addr, page, this_len, flags);
 835                 if (!this_len) {
 836                         if (!copied)
 837                                 copied = -EIO;
 838                         break;
 839                 }
 840
 841                 if (!write && copy_to_user(buf, page, this_len)) {
 842                         copied = -EFAULT;
 843                         break;
 844                 }
 845
 846                 buf += this_len;
 847                 addr += this_len;
 848                 copied += this_len;
 849                 count -= this_len;
 850         }
 851         *ppos = addr;
 852
 853         mmput(mm);
 854 free:
 855         free_page((unsigned long) page);
 856         return copied;
 857 }
 858
 859 static ssize_t mem_read(struct file *file, char __user *buf,
 860                         size_t count, loff_t *ppos)
 861 {
 862         return mem_rw(file, buf, count, ppos, 0);
 863 }
 864
 865 static ssize_t mem_write(struct file *file, const char __user *buf,
 866                          size_t count, loff_t *ppos)
 867 {
 868         return mem_rw(file, (char __user*)buf, count, ppos, 1);
 869 }
 870
 871 loff_t mem_lseek(struct file *file, loff_t offset, int orig)
 872 {
 873         switch (orig) {
 874         case 0:
 875                 file->f_pos = offset;
 876                 break;
 877         case 1:
 878                 file->f_pos += offset;
 879                 break;
 880         default:
 881                 return -EINVAL;
 882         }
 883         force_successful_syscall_return();
 884         return file->f_pos;
 885 }
 886
 887 static int mem_release(struct inode *inode, struct file *file)
 888 {
 889         struct mm_struct *mm = file->private_data;
 890         if (mm)
 891                 mmdrop(mm);
 892         return 0;
 893 }
 894
 895 static const struct file_operations proc_mem_operations = {
 896         .llseek         = mem_lseek,
 897         .read           = mem_read,
 898         .write          = mem_write,
 899         .open           = mem_open,
 900         .release        = mem_release,
 901 };
 902
 903 static int environ_open(struct inode *inode, struct file *file)
 904 {
 905         return __mem_open(inode, file, PTRACE_MODE_READ);
 906 }
 907
 908 static ssize_t environ_read(struct file *file, char __user *buf,
 909                         size_t count, loff_t *ppos)
 910 {
 911         char *page;
 912         unsigned long src = *ppos;
 913         int ret = 0;
 914         struct mm_struct *mm = file->private_data;
 915         unsigned long env_start, env_end;
 916
 917         /* Ensure the process spawned far enough to have an environment. */
 918         if (!mm || !mm->env_end)
 919                 return 0;
 920
 921         page = (char *)__get_free_page(GFP_TEMPORARY);
 922         if (!page)
 923                 return -ENOMEM;
 924
 925         ret = 0;
 926         if (!mmget_not_zero(mm))
 927                 goto free;
 928
 929         down_read(&mm->mmap_sem);
 930         env_start = mm->env_start;
 931         env_end = mm->env_end;
 932         up_read(&mm->mmap_sem);
 933
 934         while (count > 0) {
 935                 size_t this_len, max_len;
 936                 int retval;
 937
 938                 if (src >= (env_end - env_start))
 939                         break;
 940
 941                 this_len = env_end - (env_start + src);
 942
 943                 max_len = min_t(size_t, PAGE_SIZE, count);
 944                 this_len = min(max_len, this_len);
 945
 946                 retval = access_remote_vm(mm, (env_start + src), page, this_len, 0);
 947
 948                 if (retval <= 0) {
 949                         ret = retval;
 950                         break;
 951                 }
 952
 953                 if (copy_to_user(buf, page, retval)) {
 954                         ret = -EFAULT;
 955                         break;
 956                 }
 957
 958                 ret += retval;
 959                 src += retval;
 960                 buf += retval;
 961                 count -= retval;
 962         }
 963         *ppos = src;
 964         mmput(mm);
 965
 966 free:
 967         free_page((unsigned long) page);
 968         return ret;
 969 }
 970
 971 static const struct file_operations proc_environ_operations = {
 972         .open           = environ_open,
 973         .read           = environ_read,
 974         .llseek         = generic_file_llseek,
 975         .release        = mem_release,
 976 };
 977
 978 static int auxv_open(struct inode *inode, struct file *file)
 979 {
 980         return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
 981 }
 982
 983 static ssize_t auxv_read(struct file *file, char __user *buf,
 984                         size_t count, loff_t *ppos)
 985 {
 986         struct mm_struct *mm = file->private_data;
 987         unsigned int nwords = 0;
 988
 989         if (!mm)
 990                 return 0;
 991         do {
 992                 nwords += 2;
 993         } while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
 994         return simple_read_from_buffer(buf, count, ppos, mm->saved_auxv,
 995                                        nwords * sizeof(mm->saved_auxv[0]));
 996 }
 997
 998 static const struct file_operations proc_auxv_operations = {
 999         .open           = auxv_open,
1000         .read           = auxv_read,
1001         .llseek         = generic_file_llseek,
1002         .release        = mem_release,
1003 };
1004
1005 static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
1006                             loff_t *ppos)
1007 {
1008         struct task_struct *task = get_proc_task(file_inode(file));
1009         char buffer[PROC_NUMBUF];
1010         int oom_adj = OOM_ADJUST_MIN;
1011         size_t len;
1012
1013         if (!task)
1014                 return -ESRCH;
1015         if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MAX)
1016                 oom_adj = OOM_ADJUST_MAX;
1017         else
1018                 oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
1019                           OOM_SCORE_ADJ_MAX;
1020         put_task_struct(task);
1021         len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
1022         return simple_read_from_buffer(buf, count, ppos, buffer, len);
1023 }
1024
1025 static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
1026 {
1027         static DEFINE_MUTEX(oom_adj_mutex);
1028         struct mm_struct *mm = NULL;
1029         struct task_struct *task;
1030         int err = 0;
1031
1032         task = get_proc_task(file_inode(file));
1033         if (!task)
1034                 return -ESRCH;
1035
1036         mutex_lock(&oom_adj_mutex);
1037         if (legacy) {
1038                 if (oom_adj < task->signal->oom_score_adj &&
1039                                 !capable(CAP_SYS_RESOURCE)) {
1040                         err = -EACCES;
1041                         goto err_unlock;
1042                 }
1043                 /*
1044                  * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
1045                  * /proc/pid/oom_score_adj instead.
1046                  */
1047                 pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
1048                           current->comm, task_pid_nr(current), task_pid_nr(task),
1049                           task_pid_nr(task));
1050         } else {
1051                 if ((short)oom_adj < task->signal->oom_score_adj_min &&
1052                                 !capable(CAP_SYS_RESOURCE)) {
1053                         err = -EACCES;
1054                         goto err_unlock;
1055                 }
1056         }
1057
1058         /*
1059          * Make sure we will check other processes sharing the mm if this is
1060          * not vfrok which wants its own oom_score_adj.
1061          * pin the mm so it doesn't go away and get reused after task_unlock
1062          */
1063         if (!task->vfork_done) {
1064                 struct task_struct *p = find_lock_task_mm(task);
1065
1066                 if (p) {
1067                         if (atomic_read(&p->mm->mm_users) > 1) {
1068                                 mm = p->mm;
1069                                 mmgrab(mm);
1070                         }
1071                         task_unlock(p);
1072                 }
1073         }
1074
1075         task->signal->oom_score_adj = oom_adj;
1076         if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1077                 task->signal->oom_score_adj_min = (short)oom_adj;
1078         trace_oom_score_adj_update(task);
1079
1080         if (mm) {
1081                 struct task_struct *p;
1082
1083                 rcu_read_lock();
1084                 for_each_process(p) {
1085                         if (same_thread_group(task, p))
1086                                 continue;
1087
1088                         /* do not touch kernel threads or the global init */
1089                         if (p->flags & PF_KTHREAD || is_global_init(p))
1090                                 continue;
1091
1092                         task_lock(p);
1093                         if (!p->vfork_done && process_shares_mm(p, mm)) {
1094                                 pr_info("updating oom_score_adj for %d (%s) from %d to %d because it shares mm with %d (%s). Report if this is unexpected.\n",
1095                                                 task_pid_nr(p), p->comm,
1096                                                 p->signal->oom_score_adj, oom_adj,
1097                                                 task_pid_nr(task), task->comm);
1098                                 p->signal->oom_score_adj = oom_adj;
1099                                 if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
1100                                         p->signal->oom_score_adj_min = (short)oom_adj;
1101                         }
1102                         task_unlock(p);
1103                 }
1104                 rcu_read_unlock();
1105                 mmdrop(mm);
1106         }
1107 err_unlock:
1108         mutex_unlock(&oom_adj_mutex);
1109         put_task_struct(task);
1110         return err;
1111 }
1112
1113 /*
1114  * /proc/pid/oom_adj exists solely for backwards compatibility with previous
1115  * kernels.  The effective policy is defined by oom_score_adj, which has a
1116  * different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
1117  * Values written to oom_adj are simply mapped linearly to oom_score_adj.
1118  * Processes that become oom disabled via oom_adj will still be oom disabled
1119  * with this implementation.
1120  *
1121  * oom_adj cannot be removed since existing userspace binaries use it.
1122  */
1123 static ssize_t oom_adj_write(struct file *file, const char __user *buf,
1124                              size_t count, loff_t *ppos)
1125 {
1126         char buffer[PROC_NUMBUF];
1127         int oom_adj;
1128         int err;
1129
1130         memset(buffer, 0, sizeof(buffer));
1131         if (count > sizeof(buffer) - 1)
1132                 count = sizeof(buffer) - 1;
1133         if (copy_from_user(buffer, buf, count)) {
1134                 err = -EFAULT;
1135                 goto out;
1136         }
1137
1138         err = kstrtoint(strstrip(buffer), 0, &oom_adj);
1139         if (err)
1140                 goto out;
1141         if ((oom_adj < OOM_ADJUST_MIN || oom_adj > OOM_ADJUST_MAX) &&
1142              oom_adj != OOM_DISABLE) {
1143                 err = -EINVAL;
1144                 goto out;
1145         }
1146
1147         /*
1148          * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
1149          * value is always attainable.
1150          */
1151         if (oom_adj == OOM_ADJUST_MAX)
1152                 oom_adj = OOM_SCORE_ADJ_MAX;
1153         else
1154                 oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
1155
1156         err = __set_oom_adj(file, oom_adj, true);
1157 out:
1158         return err < 0 ? err : count;
1159 }
1160
1161 static const struct file_operations proc_oom_adj_operations = {
1162         .read           = oom_adj_read,
1163         .write          = oom_adj_write,
1164         .llseek         = generic_file_llseek,
1165 };
1166
1167 static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
1168                                         size_t count, loff_t *ppos)
1169 {
1170         struct task_struct *task = get_proc_task(file_inode(file));
1171         char buffer[PROC_NUMBUF];
1172         short oom_score_adj = OOM_SCORE_ADJ_MIN;
1173         size_t len;
1174
1175         if (!task)
1176                 return -ESRCH;
1177         oom_score_adj = task->signal->oom_score_adj;
1178         put_task_struct(task);
1179         len = snprintf(buffer, sizeof(buffer), "%hd\n", oom_score_adj);
1180         return simple_read_from_buffer(buf, count, ppos, buffer, len);
1181 }
1182
1183 static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
1184                                         size_t count, loff_t *ppos)
1185 {
1186         char buffer[PROC_NUMBUF];
1187         int oom_score_adj;
1188         int err;
1189
1190         memset(buffer, 0, sizeof(buffer));
1191         if (count > sizeof(buffer) - 1)
1192                 count = sizeof(buffer) - 1;
1193         if (copy_from_user(buffer, buf, count)) {
1194                 err = -EFAULT;
1195                 goto out;
1196         }
1197
1198         err = kstrtoint(strstrip(buffer), 0, &oom_score_adj);
1199         if (err)
1200                 goto out;
1201         if (oom_score_adj < OOM_SCORE_ADJ_MIN ||
1202                         oom_score_adj > OOM_SCORE_ADJ_MAX) {
1203                 err = -EINVAL;
1204                 goto out;
1205         }
1206
1207         err = __set_oom_adj(file, oom_score_adj, false);
1208 out:
1209         return err < 0 ? err : count;
1210 }
1211
1212 static const struct file_operations proc_oom_score_adj_operations = {
1213         .read           = oom_score_adj_read,
1214         .write          = oom_score_adj_write,
1215         .llseek         = default_llseek,
1216 };
1217
1218 #ifdef CONFIG_AUDITSYSCALL
1219 #define TMPBUFLEN 11
1220 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
1221                                   size_t count, loff_t *ppos)
1222 {
1223         struct inode * inode = file_inode(file);
1224         struct task_struct *task = get_proc_task(inode);
1225         ssize_t length;
1226         char tmpbuf[TMPBUFLEN];
1227
1228         if (!task)
1229                 return -ESRCH;
1230         length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1231                            from_kuid(file->f_cred->user_ns,
1232                                      audit_get_loginuid(task)));
1233         put_task_struct(task);
1234         return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1235 }
1236
1237 static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
1238                                    size_t count, loff_t *ppos)
1239 {
1240         struct inode * inode = file_inode(file);
1241         uid_t loginuid;
1242         kuid_t kloginuid;
1243         int rv;
1244
1245         rcu_read_lock();
1246         if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
1247                 rcu_read_unlock();
1248                 return -EPERM;
1249         }
1250         rcu_read_unlock();
1251
1252         if (*ppos != 0) {
1253                 /* No partial writes. */
1254                 return -EINVAL;
1255         }
1256
1257         rv = kstrtou32_from_user(buf, count, 10, &loginuid);
1258         if (rv < 0)
1259                 return rv;
1260
1261         /* is userspace tring to explicitly UNSET the loginuid? */
1262         if (loginuid == AUDIT_UID_UNSET) {
1263                 kloginuid = INVALID_UID;
1264         } else {
1265                 kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
1266                 if (!uid_valid(kloginuid))
1267                         return -EINVAL;
1268         }
1269
1270         rv = audit_set_loginuid(kloginuid);
1271         if (rv < 0)
1272                 return rv;
1273         return count;
1274 }
1275
1276 static const struct file_operations proc_loginuid_operations = {
1277         .read           = proc_loginuid_read,
1278         .write          = proc_loginuid_write,
1279         .llseek         = generic_file_llseek,
1280 };
1281
1282 static ssize_t proc_sessionid_read(struct file * file, char __user * buf,
1283                                   size_t count, loff_t *ppos)
1284 {
1285         struct inode * inode = file_inode(file);
1286         struct task_struct *task = get_proc_task(inode);
1287         ssize_t length;
1288         char tmpbuf[TMPBUFLEN];
1289
1290         if (!task)
1291                 return -ESRCH;
1292         length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
1293                                 audit_get_sessionid(task));
1294         put_task_struct(task);
1295         return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
1296 }
1297
1298 static const struct file_operations proc_sessionid_operations = {
1299         .read           = proc_sessionid_read,
1300         .llseek         = generic_file_llseek,
1301 };
1302 #endif
1303
1304 #ifdef CONFIG_FAULT_INJECTION
1305 static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
1306                                       size_t count, loff_t *ppos)
1307 {
1308         struct task_struct *task = get_proc_task(file_inode(file));
1309         char buffer[PROC_NUMBUF];
1310         size_t len;
1311         int make_it_fail;
1312
1313         if (!task)
1314                 return -ESRCH;
1315         make_it_fail = task->make_it_fail;
1316         put_task_struct(task);
1317
1318         len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
1319
1320         return simple_read_from_buffer(buf, count, ppos, buffer, len);
1321 }
1322
1323 static ssize_t proc_fault_inject_write(struct file * file,
1324                         const char __user * buf, size_t count, loff_t *ppos)
1325 {
1326         struct task_struct *task;
1327         char buffer[PROC_NUMBUF];
1328         int make_it_fail;
1329         int rv;
1330
1331         if (!capable(CAP_SYS_RESOURCE))
1332                 return -EPERM;
1333         memset(buffer, 0, sizeof(buffer));
1334         if (count > sizeof(buffer) - 1)
1335                 count = sizeof(buffer) - 1;
1336         if (copy_from_user(buffer, buf, count))
1337                 return -EFAULT;
1338         rv = kstrtoint(strstrip(buffer), 0, &make_it_fail);
1339         if (rv < 0)
1340                 return rv;
1341         if (make_it_fail < 0 || make_it_fail > 1)
1342                 return -EINVAL;
1343
1344         task = get_proc_task(file_inode(file));
1345         if (!task)
1346                 return -ESRCH;
1347         task->make_it_fail = make_it_fail;
1348         put_task_struct(task);
1349
1350         return count;
1351 }
1352
1353 static const struct file_operations proc_fault_inject_operations = {
1354         .read           = proc_fault_inject_read,
1355         .write          = proc_fault_inject_write,
1356         .llseek         = generic_file_llseek,
1357 };
1358 #endif
1359
1360
1361 #ifdef CONFIG_SCHED_DEBUG
1362 /*
1363  * Print out various scheduling related per-task fields:
1364  */
1365 static int sched_show(struct seq_file *m, void *v)
1366 {
1367         struct inode *inode = m->private;
1368         struct task_struct *p;
1369
1370         p = get_proc_task(inode);
1371         if (!p)
1372                 return -ESRCH;
1373         proc_sched_show_task(p, m);
1374
1375         put_task_struct(p);
1376
1377         return 0;
1378 }
1379
1380 static ssize_t
1381 sched_write(struct file *file, const char __user *buf,
1382             size_t count, loff_t *offset)
1383 {
1384         struct inode *inode = file_inode(file);
1385         struct task_struct *p;
1386
1387         p = get_proc_task(inode);
1388         if (!p)
1389                 return -ESRCH;
1390         proc_sched_set_task(p);
1391
1392         put_task_struct(p);
1393
1394         return count;
1395 }
1396
1397 static int sched_open(struct inode *inode, struct file *filp)
1398 {
1399         return single_open(filp, sched_show, inode);
1400 }
1401
1402 static const struct file_operations proc_pid_sched_operations = {
1403         .open           = sched_open,
1404         .read           = seq_read,
1405         .write          = sched_write,
1406         .llseek         = seq_lseek,
1407         .release        = single_release,
1408 };
1409
1410 #endif
1411
1412 #ifdef CONFIG_SCHED_AUTOGROUP
1413 /*
1414  * Print out autogroup related information:
1415  */
1416 static int sched_autogroup_show(struct seq_file *m, void *v)
1417 {
1418         struct inode *inode = m->private;
1419         struct task_struct *p;
1420
1421         p = get_proc_task(inode);
1422         if (!p)
1423                 return -ESRCH;
1424         proc_sched_autogroup_show_task(p, m);
1425
1426         put_task_struct(p);
1427
1428         return 0;
1429 }
1430
1431 static ssize_t
1432 sched_autogroup_write(struct file *file, const char __user *buf,
1433             size_t count, loff_t *offset)
1434 {
1435         struct inode *inode = file_inode(file);
1436         struct task_struct *p;
1437         char buffer[PROC_NUMBUF];
1438         int nice;
1439         int err;
1440
1441         memset(buffer, 0, sizeof(buffer));
1442         if (count > sizeof(buffer) - 1)
1443                 count = sizeof(buffer) - 1;
1444         if (copy_from_user(buffer, buf, count))
1445                 return -EFAULT;
1446
1447         err = kstrtoint(strstrip(buffer), 0, &nice);
1448         if (err < 0)
1449                 return err;
1450
1451         p = get_proc_task(inode);
1452         if (!p)
1453                 return -ESRCH;
1454
1455         err = proc_sched_autogroup_set_nice(p, nice);
1456         if (err)
1457                 count = err;
1458
1459         put_task_struct(p);
1460
1461         return count;
1462 }
1463
1464 static int sched_autogroup_open(struct inode *inode, struct file *filp)
1465 {
1466         int ret;
1467
1468         ret = single_open(filp, sched_autogroup_show, NULL);
1469         if (!ret) {
1470                 struct seq_file *m = filp->private_data;
1471
1472                 m->private = inode;
1473         }
1474         return ret;
1475 }
1476
1477 static const struct file_operations proc_pid_sched_autogroup_operations = {
1478         .open           = sched_autogroup_open,
1479         .read           = seq_read,
1480         .write          = sched_autogroup_write,
1481         .llseek         = seq_lseek,
1482         .release        = single_release,
1483 };
1484
1485 #endif /* CONFIG_SCHED_AUTOGROUP */
1486
1487 static ssize_t comm_write(struct file *file, const char __user *buf,
1488                                 size_t count, loff_t *offset)
1489 {
1490         struct inode *inode = file_inode(file);
1491         struct task_struct *p;
1492         char buffer[TASK_COMM_LEN];
1493         const size_t maxlen = sizeof(buffer) - 1;
1494
1495         memset(buffer, 0, sizeof(buffer));
1496         if (copy_from_user(buffer, buf, count > maxlen ? maxlen : count))
1497                 return -EFAULT;
1498
1499         p = get_proc_task(inode);
1500         if (!p)
1501                 return -ESRCH;
1502
1503         if (same_thread_group(current, p))
1504                 set_task_comm(p, buffer);
1505         else
1506                 count = -EINVAL;
1507
1508         put_task_struct(p);
1509
1510         return count;
1511 }
1512
1513 static int comm_show(struct seq_file *m, void *v)
1514 {
1515         struct inode *inode = m->private;
1516         struct task_struct *p;
1517
1518         p = get_proc_task(inode);
1519         if (!p)
1520                 return -ESRCH;
1521
1522         task_lock(p);
1523         seq_printf(m, "%s\n", p->comm);
1524         task_unlock(p);
1525
1526         put_task_struct(p);
1527
1528         return 0;
1529 }
1530
1531 static int comm_open(struct inode *inode, struct file *filp)
1532 {
1533         return single_open(filp, comm_show, inode);
1534 }
1535
1536 static const struct file_operations proc_pid_set_comm_operations = {
1537         .open           = comm_open,
1538         .read           = seq_read,
1539         .write          = comm_write,
1540         .llseek         = seq_lseek,
1541         .release        = single_release,
1542 };
1543
1544 static int proc_exe_link(struct dentry *dentry, struct path *exe_path)
1545 {
1546         struct task_struct *task;
1547         struct file *exe_file;
1548
1549         task = get_proc_task(d_inode(dentry));
1550         if (!task)
1551                 return -ENOENT;
1552         exe_file = get_task_exe_file(task);
1553         put_task_struct(task);
1554         if (exe_file) {
1555                 *exe_path = exe_file->f_path;
1556                 path_get(&exe_file->f_path);
1557                 fput(exe_file);
1558                 return 0;
1559         } else
1560                 return -ENOENT;
1561 }
1562
1563 static const char *proc_pid_get_link(struct dentry *dentry,
1564                                      struct inode *inode,
1565                                      struct delayed_call *done)
1566 {
1567         struct path path;
1568         int error = -EACCES;
1569
1570         if (!dentry)
1571                 return ERR_PTR(-ECHILD);
1572
1573         /* Are we allowed to snoop on the tasks file descriptors? */
1574         if (!proc_fd_access_allowed(inode))
1575                 goto out;
1576
1577         error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1578         if (error)
1579                 goto out;
1580
1581         nd_jump_link(&path);
1582         return NULL;
1583 out:
1584         return ERR_PTR(error);
1585 }
1586
1587 static int do_proc_readlink(struct path *path, char __user *buffer, int buflen)
1588 {
1589         char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
1590         char *pathname;
1591         int len;
1592
1593         if (!tmp)
1594                 return -ENOMEM;
1595
1596         pathname = d_path(path, tmp, PAGE_SIZE);
1597         len = PTR_ERR(pathname);
1598         if (IS_ERR(pathname))
1599                 goto out;
1600         len = tmp + PAGE_SIZE - 1 - pathname;
1601
1602         if (len > buflen)
1603                 len = buflen;
1604         if (copy_to_user(buffer, pathname, len))
1605                 len = -EFAULT;
1606  out:
1607         free_page((unsigned long)tmp);
1608         return len;
1609 }
1610
1611 static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
1612 {
1613         int error = -EACCES;
1614         struct inode *inode = d_inode(dentry);
1615         struct path path;
1616
1617         /* Are we allowed to snoop on the tasks file descriptors? */
1618         if (!proc_fd_access_allowed(inode))
1619                 goto out;
1620
1621         error = PROC_I(inode)->op.proc_get_link(dentry, &path);
1622         if (error)
1623                 goto out;
1624
1625         error = do_proc_readlink(&path, buffer, buflen);
1626         path_put(&path);
1627 out:
1628         return error;
1629 }
1630
1631 const struct inode_operations proc_pid_link_inode_operations = {
1632         .readlink       = proc_pid_readlink,
1633         .get_link       = proc_pid_get_link,
1634         .setattr        = proc_setattr,
1635 };
1636
1637
1638 /* building an inode */
1639
1640 void task_dump_owner(struct task_struct *task, mode_t mode,
1641                      kuid_t *ruid, kgid_t *rgid)
1642 {
1643         /* Depending on the state of dumpable compute who should own a
1644          * proc file for a task.
1645          */
1646         const struct cred *cred;
1647         kuid_t uid;
1648         kgid_t gid;
1649
1650         /* Default to the tasks effective ownership */
1651         rcu_read_lock();
1652         cred = __task_cred(task);
1653         uid = cred->euid;
1654         gid = cred->egid;
1655         rcu_read_unlock();
1656
1657         /*
1658          * Before the /proc/pid/status file was created the only way to read
1659          * the effective uid of a /process was to stat /proc/pid.  Reading
1660          * /proc/pid/status is slow enough that procps and other packages
1661          * kept stating /proc/pid.  To keep the rules in /proc simple I have
1662          * made this apply to all per process world readable and executable
1663          * directories.
1664          */
1665         if (mode != (S_IFDIR|S_IRUGO|S_IXUGO)) {
1666                 struct mm_struct *mm;
1667                 task_lock(task);
1668                 mm = task->mm;
1669                 /* Make non-dumpable tasks owned by some root */
1670                 if (mm) {
1671                         if (get_dumpable(mm) != SUID_DUMP_USER) {
1672                                 struct user_namespace *user_ns = mm->user_ns;
1673
1674                                 uid = make_kuid(user_ns, 0);
1675                                 if (!uid_valid(uid))
1676                                         uid = GLOBAL_ROOT_UID;
1677
1678                                 gid = make_kgid(user_ns, 0);
1679                                 if (!gid_valid(gid))
1680                                         gid = GLOBAL_ROOT_GID;
1681                         }
1682                 } else {
1683                         uid = GLOBAL_ROOT_UID;
1684                         gid = GLOBAL_ROOT_GID;
1685                 }
1686                 task_unlock(task);
1687         }
1688         *ruid = uid;
1689         *rgid = gid;
1690 }
1691
1692 struct inode *proc_pid_make_inode(struct super_block * sb,
1693                                   struct task_struct *task, umode_t mode)
1694 {
1695         struct inode * inode;
1696         struct proc_inode *ei;
1697
1698         /* We need a new inode */
1699
1700         inode = new_inode(sb);
1701         if (!inode)
1702                 goto out;
1703
1704         /* Common stuff */
1705         ei = PROC_I(inode);
1706         inode->i_mode = mode;
1707         inode->i_ino = get_next_ino();
1708         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
1709         inode->i_op = &proc_def_inode_operations;
1710
1711         /*
1712          * grab the reference to task.
1713          */
1714         ei->pid = get_task_pid(task, PIDTYPE_PID);
1715         if (!ei->pid)
1716                 goto out_unlock;
1717
1718         task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
1719         security_task_to_inode(task, inode);
1720
1721 out:
1722         return inode;
1723
1724 out_unlock:
1725         iput(inode);
1726         return NULL;
1727 }
1728
1729 int pid_getattr(const struct path *path, struct kstat *stat,
1730                 u32 request_mask, unsigned int query_flags)
1731 {
1732         struct inode *inode = d_inode(path->dentry);
1733         struct task_struct *task;
1734         struct pid_namespace *pid = path->dentry->d_sb->s_fs_info;
1735
1736         generic_fillattr(inode, stat);
1737
1738         rcu_read_lock();
1739         stat->uid = GLOBAL_ROOT_UID;
1740         stat->gid = GLOBAL_ROOT_GID;
1741         task = pid_task(proc_pid(inode), PIDTYPE_PID);
1742         if (task) {
1743                 if (!has_pid_permissions(pid, task, HIDEPID_INVISIBLE)) {
1744                         rcu_read_unlock();
1745                         /*
1746                          * This doesn't prevent learning whether PID exists,
1747                          * it only makes getattr() consistent with readdir().
1748                          */
1749                         return -ENOENT;
1750                 }
1751                 task_dump_owner(task, inode->i_mode, &stat->uid, &stat->gid);
1752         }
1753         rcu_read_unlock();
1754         return 0;
1755 }
1756
1757 /* dentry stuff */
1758
1759 /*
1760  *      Exceptional case: normally we are not allowed to unhash a busy
1761  * directory. In this case, however, we can do it - no aliasing problems
1762  * due to the way we treat inodes.
1763  *
1764  * Rewrite the inode's ownerships here because the owning task may have
1765  * performed a setuid(), etc.
1766  *
1767  */
1768 int pid_revalidate(struct dentry *dentry, unsigned int flags)
1769 {
1770         struct inode *inode;
1771         struct task_struct *task;
1772
1773         if (flags & LOOKUP_RCU)
1774                 return -ECHILD;
1775
1776         inode = d_inode(dentry);
1777         task = get_proc_task(inode);
1778
1779         if (task) {
1780                 task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
1781
1782                 inode->i_mode &= ~(S_ISUID | S_ISGID);
1783                 security_task_to_inode(task, inode);
1784                 put_task_struct(task);
1785                 return 1;
1786         }
1787         return 0;
1788 }
1789
1790 static inline bool proc_inode_is_dead(struct inode *inode)
1791 {
1792         return !proc_pid(inode)->tasks[PIDTYPE_PID].first;
1793 }
1794
1795 int pid_delete_dentry(const struct dentry *dentry)
1796 {
1797         /* Is the task we represent dead?
1798          * If so, then don't put the dentry on the lru list,
1799          * kill it immediately.
1800          */
1801         return proc_inode_is_dead(d_inode(dentry));
1802 }
1803
1804 const struct dentry_operations pid_dentry_operations =
1805 {
1806         .d_revalidate   = pid_revalidate,
1807         .d_delete       = pid_delete_dentry,
1808 };
1809
1810 /* Lookups */
1811
1812 /*
1813  * Fill a directory entry.
1814  *
1815  * If possible create the dcache entry and derive our inode number and
1816  * file type from dcache entry.
1817  *
1818  * Since all of the proc inode numbers are dynamically generated, the inode
1819  * numbers do not exist until the inode is cache.  This means creating the
1820  * the dcache entry in readdir is necessary to keep the inode numbers
1821  * reported by readdir in sync with the inode numbers reported
1822  * by stat.
1823  */
1824 bool proc_fill_cache(struct file *file, struct dir_context *ctx,
1825         const char *name, int len,
1826         instantiate_t instantiate, struct task_struct *task, const void *ptr)
1827 {
1828         struct dentry *child, *dir = file->f_path.dentry;
1829         struct qstr qname = QSTR_INIT(name, len);
1830         struct inode *inode;
1831         unsigned type;
1832         ino_t ino;
1833
1834         child = d_hash_and_lookup(dir, &qname);
1835         if (!child) {
1836                 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1837                 child = d_alloc_parallel(dir, &qname, &wq);
1838                 if (IS_ERR(child))
1839                         goto end_instantiate;
1840                 if (d_in_lookup(child)) {
1841                         int err = instantiate(d_inode(dir), child, task, ptr);
1842                         d_lookup_done(child);
1843                         if (err < 0) {
1844                                 dput(child);
1845                                 goto end_instantiate;
1846                         }
1847                 }
1848         }
1849         inode = d_inode(child);
1850         ino = inode->i_ino;
1851         type = inode->i_mode >> 12;
1852         dput(child);
1853         return dir_emit(ctx, name, len, ino, type);
1854
1855 end_instantiate:
1856         return dir_emit(ctx, name, len, 1, DT_UNKNOWN);
1857 }
1858
1859 /*
1860  * dname_to_vma_addr - maps a dentry name into two unsigned longs
1861  * which represent vma start and end addresses.
1862  */
1863 static int dname_to_vma_addr(struct dentry *dentry,
1864                              unsigned long *start, unsigned long *end)
1865 {
1866         if (sscanf(dentry->d_name.name, "%lx-%lx", start, end) != 2)
1867                 return -EINVAL;
1868
1869         return 0;
1870 }
1871
1872 static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags)
1873 {
1874         unsigned long vm_start, vm_end;
1875         bool exact_vma_exists = false;
1876         struct mm_struct *mm = NULL;
1877         struct task_struct *task;
1878         struct inode *inode;
1879         int status = 0;
1880
1881         if (flags & LOOKUP_RCU)
1882                 return -ECHILD;
1883
1884         inode = d_inode(dentry);
1885         task = get_proc_task(inode);
1886         if (!task)
1887                 goto out_notask;
1888
1889         mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1890         if (IS_ERR_OR_NULL(mm))
1891                 goto out;
1892
1893         if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
1894                 down_read(&mm->mmap_sem);
1895                 exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
1896                 up_read(&mm->mmap_sem);
1897         }
1898
1899         mmput(mm);
1900
1901         if (exact_vma_exists) {
1902                 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
1903
1904                 security_task_to_inode(task, inode);
1905                 status = 1;
1906         }
1907
1908 out:
1909         put_task_struct(task);
1910
1911 out_notask:
1912         return status;
1913 }
1914
1915 static const struct dentry_operations tid_map_files_dentry_operations = {
1916         .d_revalidate   = map_files_d_revalidate,
1917         .d_delete       = pid_delete_dentry,
1918 };
1919
1920 static int map_files_get_link(struct dentry *dentry, struct path *path)
1921 {
1922         unsigned long vm_start, vm_end;
1923         struct vm_area_struct *vma;
1924         struct task_struct *task;
1925         struct mm_struct *mm;
1926         int rc;
1927
1928         rc = -ENOENT;
1929         task = get_proc_task(d_inode(dentry));
1930         if (!task)
1931                 goto out;
1932
1933         mm = get_task_mm(task);
1934         put_task_struct(task);
1935         if (!mm)
1936                 goto out;
1937
1938         rc = dname_to_vma_addr(dentry, &vm_start, &vm_end);
1939         if (rc)
1940                 goto out_mmput;
1941
1942         rc = -ENOENT;
1943         down_read(&mm->mmap_sem);
1944         vma = find_exact_vma(mm, vm_start, vm_end);
1945         if (vma && vma->vm_file) {
1946                 *path = vma->vm_file->f_path;
1947                 path_get(path);
1948                 rc = 0;
1949         }
1950         up_read(&mm->mmap_sem);
1951
1952 out_mmput:
1953         mmput(mm);
1954 out:
1955         return rc;
1956 }
1957
1958 struct map_files_info {
1959         fmode_t         mode;
1960         unsigned int    len;
1961         unsigned char   name[4*sizeof(long)+2]; /* max: %lx-%lx\0 */
1962 };
1963
1964 /*
1965  * Only allow CAP_SYS_ADMIN to follow the links, due to concerns about how the
1966  * symlinks may be used to bypass permissions on ancestor directories in the
1967  * path to the file in question.
1968  */
1969 static const char *
1970 proc_map_files_get_link(struct dentry *dentry,
1971                         struct inode *inode,
1972                         struct delayed_call *done)
1973 {
1974         if (!capable(CAP_SYS_ADMIN))
1975                 return ERR_PTR(-EPERM);
1976
1977         return proc_pid_get_link(dentry, inode, done);
1978 }
1979
1980 /*
1981  * Identical to proc_pid_link_inode_operations except for get_link()
1982  */
1983 static const struct inode_operations proc_map_files_link_inode_operations = {
1984         .readlink       = proc_pid_readlink,
1985         .get_link       = proc_map_files_get_link,
1986         .setattr        = proc_setattr,
1987 };
1988
1989 static int
1990 proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
1991                            struct task_struct *task, const void *ptr)
1992 {
1993         fmode_t mode = (fmode_t)(unsigned long)ptr;
1994         struct proc_inode *ei;
1995         struct inode *inode;
1996
1997         inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK |
1998                                     ((mode & FMODE_READ ) ? S_IRUSR : 0) |
1999                                     ((mode & FMODE_WRITE) ? S_IWUSR : 0));
2000         if (!inode)
2001                 return -ENOENT;
2002
2003         ei = PROC_I(inode);
2004         ei->op.proc_get_link = map_files_get_link;
2005
2006         inode->i_op = &proc_map_files_link_inode_operations;
2007         inode->i_size = 64;
2008
2009         d_set_d_op(dentry, &tid_map_files_dentry_operations);
2010         d_add(dentry, inode);
2011
2012         return 0;
2013 }
2014
2015 static struct dentry *proc_map_files_lookup(struct inode *dir,
2016                 struct dentry *dentry, unsigned int flags)
2017 {
2018         unsigned long vm_start, vm_end;
2019         struct vm_area_struct *vma;
2020         struct task_struct *task;
2021         int result;
2022         struct mm_struct *mm;
2023
2024         result = -ENOENT;
2025         task = get_proc_task(dir);
2026         if (!task)
2027                 goto out;
2028
2029         result = -EACCES;
2030         if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2031                 goto out_put_task;
2032
2033         result = -ENOENT;
2034         if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
2035                 goto out_put_task;
2036
2037         mm = get_task_mm(task);
2038         if (!mm)
2039                 goto out_put_task;
2040
2041         down_read(&mm->mmap_sem);
2042         vma = find_exact_vma(mm, vm_start, vm_end);
2043         if (!vma)
2044                 goto out_no_vma;
2045
2046         if (vma->vm_file)
2047                 result = proc_map_files_instantiate(dir, dentry, task,
2048                                 (void *)(unsigned long)vma->vm_file->f_mode);
2049
2050 out_no_vma:
2051         up_read(&mm->mmap_sem);
2052         mmput(mm);
2053 out_put_task:
2054         put_task_struct(task);
2055 out:
2056         return ERR_PTR(result);
2057 }
2058
2059 static const struct inode_operations proc_map_files_inode_operations = {
2060         .lookup         = proc_map_files_lookup,
2061         .permission     = proc_fd_permission,
2062         .setattr        = proc_setattr,
2063 };
2064
2065 static int
2066 proc_map_files_readdir(struct file *file, struct dir_context *ctx)
2067 {
2068         struct vm_area_struct *vma;
2069         struct task_struct *task;
2070         struct mm_struct *mm;
2071         unsigned long nr_files, pos, i;
2072         struct flex_array *fa = NULL;
2073         struct map_files_info info;
2074         struct map_files_info *p;
2075         int ret;
2076
2077         ret = -ENOENT;
2078         task = get_proc_task(file_inode(file));
2079         if (!task)
2080                 goto out;
2081
2082         ret = -EACCES;
2083         if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
2084                 goto out_put_task;
2085
2086         ret = 0;
2087         if (!dir_emit_dots(file, ctx))
2088                 goto out_put_task;
2089
2090         mm = get_task_mm(task);
2091         if (!mm)
2092                 goto out_put_task;
2093         down_read(&mm->mmap_sem);
2094
2095         nr_files = 0;
2096
2097         /*
2098          * We need two passes here:
2099          *
2100          *  1) Collect vmas of mapped files with mmap_sem taken
2101          *  2) Release mmap_sem and instantiate entries
2102          *
2103          * otherwise we get lockdep complained, since filldir()
2104          * routine might require mmap_sem taken in might_fault().
2105          */
2106
2107         for (vma = mm->mmap, pos = 2; vma; vma = vma->vm_next) {
2108                 if (vma->vm_file && ++pos > ctx->pos)
2109                         nr_files++;
2110         }
2111
2112         if (nr_files) {
2113                 fa = flex_array_alloc(sizeof(info), nr_files,
2114                                         GFP_KERNEL);
2115                 if (!fa || flex_array_prealloc(fa, 0, nr_files,
2116                                                 GFP_KERNEL)) {
2117                         ret = -ENOMEM;
2118                         if (fa)
2119                                 flex_array_free(fa);
2120                         up_read(&mm->mmap_sem);
2121                         mmput(mm);
2122                         goto out_put_task;
2123                 }
2124                 for (i = 0, vma = mm->mmap, pos = 2; vma;
2125                                 vma = vma->vm_next) {
2126                         if (!vma->vm_file)
2127                                 continue;
2128                         if (++pos <= ctx->pos)
2129                                 continue;
2130
2131                         info.mode = vma->vm_file->f_mode;
2132                         info.len = snprintf(info.name,
2133                                         sizeof(info.name), "%lx-%lx",
2134                                         vma->vm_start, vma->vm_end);
2135                         if (flex_array_put(fa, i++, &info, GFP_KERNEL))
2136                                 BUG();
2137                 }
2138         }
2139         up_read(&mm->mmap_sem);
2140
2141         for (i = 0; i < nr_files; i++) {
2142                 p = flex_array_get(fa, i);
2143                 if (!proc_fill_cache(file, ctx,
2144                                       p->name, p->len,
2145                                       proc_map_files_instantiate,
2146                                       task,
2147                                       (void *)(unsigned long)p->mode))
2148                         break;
2149                 ctx->pos++;
2150         }
2151         if (fa)
2152                 flex_array_free(fa);
2153         mmput(mm);
2154
2155 out_put_task:
2156         put_task_struct(task);
2157 out:
2158         return ret;
2159 }
2160
2161 static const struct file_operations proc_map_files_operations = {
2162         .read           = generic_read_dir,
2163         .iterate_shared = proc_map_files_readdir,
2164         .llseek         = generic_file_llseek,
2165 };
2166
2167 #if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
2168 struct timers_private {
2169         struct pid *pid;
2170         struct task_struct *task;
2171         struct sighand_struct *sighand;
2172         struct pid_namespace *ns;
2173         unsigned long flags;
2174 };
2175
2176 static void *timers_start(struct seq_file *m, loff_t *pos)
2177 {
2178         struct timers_private *tp = m->private;
2179
2180         tp->task = get_pid_task(tp->pid, PIDTYPE_PID);
2181         if (!tp->task)
2182                 return ERR_PTR(-ESRCH);
2183
2184         tp->sighand = lock_task_sighand(tp->task, &tp->flags);
2185         if (!tp->sighand)
2186                 return ERR_PTR(-ESRCH);
2187
2188         return seq_list_start(&tp->task->signal->posix_timers, *pos);
2189 }
2190
2191 static void *timers_next(struct seq_file *m, void *v, loff_t *pos)
2192 {
2193         struct timers_private *tp = m->private;
2194         return seq_list_next(v, &tp->task->signal->posix_timers, pos);
2195 }
2196
2197 static void timers_stop(struct seq_file *m, void *v)
2198 {
2199         struct timers_private *tp = m->private;
2200
2201         if (tp->sighand) {
2202                 unlock_task_sighand(tp->task, &tp->flags);
2203                 tp->sighand = NULL;
2204         }
2205
2206         if (tp->task) {
2207                 put_task_struct(tp->task);
2208                 tp->task = NULL;
2209         }
2210 }
2211
2212 static int show_timer(struct seq_file *m, void *v)
2213 {
2214         struct k_itimer *timer;
2215         struct timers_private *tp = m->private;
2216         int notify;
2217         static const char * const nstr[] = {
2218                 [SIGEV_SIGNAL] = "signal",
2219                 [SIGEV_NONE] = "none",
2220                 [SIGEV_THREAD] = "thread",
2221         };
2222
2223         timer = list_entry((struct list_head *)v, struct k_itimer, list);
2224         notify = timer->it_sigev_notify;
2225
2226         seq_printf(m, "ID: %d\n", timer->it_id);
2227         seq_printf(m, "signal: %d/%p\n",
2228                    timer->sigq->info.si_signo,
2229                    timer->sigq->info.si_value.sival_ptr);
2230         seq_printf(m, "notify: %s/%s.%d\n",
2231                    nstr[notify & ~SIGEV_THREAD_ID],
2232                    (notify & SIGEV_THREAD_ID) ? "tid" : "pid",
2233                    pid_nr_ns(timer->it_pid, tp->ns));
2234         seq_printf(m, "ClockID: %d\n", timer->it_clock);
2235
2236         return 0;
2237 }
2238
2239 static const struct seq_operations proc_timers_seq_ops = {
2240         .start  = timers_start,
2241         .next   = timers_next,
2242         .stop   = timers_stop,
2243         .show   = show_timer,
2244 };
2245
2246 static int proc_timers_open(struct inode *inode, struct file *file)
2247 {
2248         struct timers_private *tp;
2249
2250         tp = __seq_open_private(file, &proc_timers_seq_ops,
2251                         sizeof(struct timers_private));
2252         if (!tp)
2253                 return -ENOMEM;
2254
2255         tp->pid = proc_pid(inode);
2256         tp->ns = inode->i_sb->s_fs_info;
2257         return 0;
2258 }
2259
2260 static const struct file_operations proc_timers_operations = {
2261         .open           = proc_timers_open,
2262         .read           = seq_read,
2263         .llseek         = seq_lseek,
2264         .release        = seq_release_private,
2265 };
2266 #endif
2267
2268 static ssize_t timerslack_ns_write(struct file *file, const char __user *buf,
2269                                         size_t count, loff_t *offset)
2270 {
2271         struct inode *inode = file_inode(file);
2272         struct task_struct *p;
2273         u64 slack_ns;
2274         int err;
2275
2276         err = kstrtoull_from_user(buf, count, 10, &slack_ns);
2277         if (err < 0)
2278                 return err;
2279
2280         p = get_proc_task(inode);
2281         if (!p)
2282                 return -ESRCH;
2283
2284         if (p != current) {
2285                 if (!capable(CAP_SYS_NICE)) {
2286                         count = -EPERM;
2287                         goto out;
2288                 }
2289
2290                 err = security_task_setscheduler(p);
2291                 if (err) {
2292                         count = err;
2293                         goto out;
2294                 }
2295         }
2296
2297         task_lock(p);
2298         if (slack_ns == 0)
2299                 p->timer_slack_ns = p->default_timer_slack_ns;
2300         else
2301                 p->timer_slack_ns = slack_ns;
2302         task_unlock(p);
2303
2304 out:
2305         put_task_struct(p);
2306
2307         return count;
2308 }
2309
2310 static int timerslack_ns_show(struct seq_file *m, void *v)
2311 {
2312         struct inode *inode = m->private;
2313         struct task_struct *p;
2314         int err = 0;
2315
2316         p = get_proc_task(inode);
2317         if (!p)
2318                 return -ESRCH;
2319
2320         if (p != current) {
2321
2322                 if (!capable(CAP_SYS_NICE)) {
2323                         err = -EPERM;
2324                         goto out;
2325                 }
2326                 err = security_task_getscheduler(p);
2327                 if (err)
2328                         goto out;
2329         }
2330
2331         task_lock(p);
2332         seq_printf(m, "%llu\n", p->timer_slack_ns);
2333         task_unlock(p);
2334
2335 out:
2336         put_task_struct(p);
2337
2338         return err;
2339 }
2340
2341 static int timerslack_ns_open(struct inode *inode, struct file *filp)
2342 {
2343         return single_open(filp, timerslack_ns_show, inode);
2344 }
2345
2346 static const struct file_operations proc_pid_set_timerslack_ns_operations = {
2347         .open           = timerslack_ns_open,
2348         .read           = seq_read,
2349         .write          = timerslack_ns_write,
2350         .llseek         = seq_lseek,
2351         .release        = single_release,
2352 };
2353
2354 static int proc_pident_instantiate(struct inode *dir,
2355         struct dentry *dentry, struct task_struct *task, const void *ptr)
2356 {
2357         const struct pid_entry *p = ptr;
2358         struct inode *inode;
2359         struct proc_inode *ei;
2360
2361         inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
2362         if (!inode)
2363                 goto out;
2364
2365         ei = PROC_I(inode);
2366         if (S_ISDIR(inode->i_mode))
2367                 set_nlink(inode, 2);    /* Use getattr to fix if necessary */
2368         if (p->iop)
2369                 inode->i_op = p->iop;
2370         if (p->fop)
2371                 inode->i_fop = p->fop;
2372         ei->op = p->op;
2373         d_set_d_op(dentry, &pid_dentry_operations);
2374         d_add(dentry, inode);
2375         /* Close the race of the process dying before we return the dentry */
2376         if (pid_revalidate(dentry, 0))
2377                 return 0;
2378 out:
2379         return -ENOENT;
2380 }
2381
2382 static struct dentry *proc_pident_lookup(struct inode *dir,
2383                                          struct dentry *dentry,
2384                                          const struct pid_entry *ents,
2385                                          unsigned int nents)
2386 {
2387         int error;
2388         struct task_struct *task = get_proc_task(dir);
2389         const struct pid_entry *p, *last;
2390
2391         error = -ENOENT;
2392
2393         if (!task)
2394                 goto out_no_task;
2395
2396         /*
2397          * Yes, it does not scale. And it should not. Don't add
2398          * new entries into /proc/<tgid>/ without very good reasons.
2399          */
2400         last = &ents[nents];
2401         for (p = ents; p < last; p++) {
2402                 if (p->len != dentry->d_name.len)
2403                         continue;
2404                 if (!memcmp(dentry->d_name.name, p->name, p->len))
2405                         break;
2406         }
2407         if (p >= last)
2408                 goto out;
2409
2410         error = proc_pident_instantiate(dir, dentry, task, p);
2411 out:
2412         put_task_struct(task);
2413 out_no_task:
2414         return ERR_PTR(error);
2415 }
2416
2417 static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
2418                 const struct pid_entry *ents, unsigned int nents)
2419 {
2420         struct task_struct *task = get_proc_task(file_inode(file));
2421         const struct pid_entry *p;
2422
2423         if (!task)
2424                 return -ENOENT;
2425
2426         if (!dir_emit_dots(file, ctx))
2427                 goto out;
2428
2429         if (ctx->pos >= nents + 2)
2430                 goto out;
2431
2432         for (p = ents + (ctx->pos - 2); p < ents + nents; p++) {
2433                 if (!proc_fill_cache(file, ctx, p->name, p->len,
2434                                 proc_pident_instantiate, task, p))
2435                         break;
2436                 ctx->pos++;
2437         }
2438 out:
2439         put_task_struct(task);
2440         return 0;
2441 }
2442
2443 #ifdef CONFIG_SECURITY
2444 static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
2445                                   size_t count, loff_t *ppos)
2446 {
2447         struct inode * inode = file_inode(file);
2448         char *p = NULL;
2449         ssize_t length;
2450         struct task_struct *task = get_proc_task(inode);
2451
2452         if (!task)
2453                 return -ESRCH;
2454
2455         length = security_getprocattr(task,
2456                                       (char*)file->f_path.dentry->d_name.name,
2457                                       &p);
2458         put_task_struct(task);
2459         if (length > 0)
2460                 length = simple_read_from_buffer(buf, count, ppos, p, length);
2461         kfree(p);
2462         return length;
2463 }
2464
2465 static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
2466                                    size_t count, loff_t *ppos)
2467 {
2468         struct inode * inode = file_inode(file);
2469         void *page;
2470         ssize_t length;
2471         struct task_struct *task = get_proc_task(inode);
2472
2473         length = -ESRCH;
2474         if (!task)
2475                 goto out_no_task;
2476
2477         /* A task may only write its own attributes. */
2478         length = -EACCES;
2479         if (current != task)
2480                 goto out;
2481
2482         if (count > PAGE_SIZE)
2483                 count = PAGE_SIZE;
2484
2485         /* No partial writes. */
2486         length = -EINVAL;
2487         if (*ppos != 0)
2488                 goto out;
2489
2490         page = memdup_user(buf, count);
2491         if (IS_ERR(page)) {
2492                 length = PTR_ERR(page);
2493                 goto out;
2494         }
2495
2496         /* Guard against adverse ptrace interaction */
2497         length = mutex_lock_interruptible(&current->signal->cred_guard_mutex);
2498         if (length < 0)
2499                 goto out_free;
2500
2501         length = security_setprocattr(file->f_path.dentry->d_name.name,
2502                                       page, count);
2503         mutex_unlock(&current->signal->cred_guard_mutex);
2504 out_free:
2505         kfree(page);
2506 out:
2507         put_task_struct(task);
2508 out_no_task:
2509         return length;
2510 }
2511
2512 static const struct file_operations proc_pid_attr_operations = {
2513         .read           = proc_pid_attr_read,
2514         .write          = proc_pid_attr_write,
2515         .llseek         = generic_file_llseek,
2516 };
2517
2518 static const struct pid_entry attr_dir_stuff[] = {
2519         REG("current",    S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2520         REG("prev",       S_IRUGO,         proc_pid_attr_operations),
2521         REG("exec",       S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2522         REG("fscreate",   S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2523         REG("keycreate",  S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2524         REG("sockcreate", S_IRUGO|S_IWUGO, proc_pid_attr_operations),
2525 };
2526
2527 static int proc_attr_dir_readdir(struct file *file, struct dir_context *ctx)
2528 {
2529         return proc_pident_readdir(file, ctx,
2530                                    attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2531 }
2532
2533 static const struct file_operations proc_attr_dir_operations = {
2534         .read           = generic_read_dir,
2535         .iterate_shared = proc_attr_dir_readdir,
2536         .llseek         = generic_file_llseek,
2537 };
2538
2539 static struct dentry *proc_attr_dir_lookup(struct inode *dir,
2540                                 struct dentry *dentry, unsigned int flags)
2541 {
2542         return proc_pident_lookup(dir, dentry,
2543                                   attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
2544 }
2545
2546 static const struct inode_operations proc_attr_dir_inode_operations = {
2547         .lookup         = proc_attr_dir_lookup,
2548         .getattr        = pid_getattr,
2549         .setattr        = proc_setattr,
2550 };
2551
2552 #endif
2553
2554 #ifdef CONFIG_ELF_CORE
2555 static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
2556                                          size_t count, loff_t *ppos)
2557 {
2558         struct task_struct *task = get_proc_task(file_inode(file));
2559         struct mm_struct *mm;
2560         char buffer[PROC_NUMBUF];
2561         size_t len;
2562         int ret;
2563
2564         if (!task)
2565                 return -ESRCH;
2566
2567         ret = 0;
2568         mm = get_task_mm(task);
2569         if (mm) {
2570                 len = snprintf(buffer, sizeof(buffer), "%08lx\n",
2571                                ((mm->flags & MMF_DUMP_FILTER_MASK) >>
2572                                 MMF_DUMP_FILTER_SHIFT));
2573                 mmput(mm);
2574                 ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
2575         }
2576
2577         put_task_struct(task);
2578
2579         return ret;
2580 }
2581
2582 static ssize_t proc_coredump_filter_write(struct file *file,
2583                                           const char __user *buf,
2584                                           size_t count,
2585                                           loff_t *ppos)
2586 {
2587         struct task_struct *task;
2588         struct mm_struct *mm;
2589         unsigned int val;
2590         int ret;
2591         int i;
2592         unsigned long mask;
2593
2594         ret = kstrtouint_from_user(buf, count, 0, &val);
2595         if (ret < 0)
2596                 return ret;
2597
2598         ret = -ESRCH;
2599         task = get_proc_task(file_inode(file));
2600         if (!task)
2601                 goto out_no_task;
2602
2603         mm = get_task_mm(task);
2604         if (!mm)
2605                 goto out_no_mm;
2606         ret = 0;
2607
2608         for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
2609                 if (val & mask)
2610                         set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2611                 else
2612                         clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
2613         }
2614
2615         mmput(mm);
2616  out_no_mm:
2617         put_task_struct(task);
2618  out_no_task:
2619         if (ret < 0)
2620                 return ret;
2621         return count;
2622 }
2623
2624 static const struct file_operations proc_coredump_filter_operations = {
2625         .read           = proc_coredump_filter_read,
2626         .write          = proc_coredump_filter_write,
2627         .llseek         = generic_file_llseek,
2628 };
2629 #endif
2630
2631 #ifdef CONFIG_TASK_IO_ACCOUNTING
2632 static int do_io_accounting(struct task_struct *task, struct seq_file *m, int whole)
2633 {
2634         struct task_io_accounting acct = task->ioac;
2635         unsigned long flags;
2636         int result;
2637
2638         result = mutex_lock_killable(&task->signal->cred_guard_mutex);
2639         if (result)
2640                 return result;
2641
2642         if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
2643                 result = -EACCES;
2644                 goto out_unlock;
2645         }
2646
2647         if (whole && lock_task_sighand(task, &flags)) {
2648                 struct task_struct *t = task;
2649
2650                 task_io_accounting_add(&acct, &task->signal->ioac);
2651                 while_each_thread(task, t)
2652                         task_io_accounting_add(&acct, &t->ioac);
2653
2654                 unlock_task_sighand(task, &flags);
2655         }
2656         seq_printf(m,
2657                    "rchar: %llu\n"
2658                    "wchar: %llu\n"
2659                    "syscr: %llu\n"
2660                    "syscw: %llu\n"
2661                    "read_bytes: %llu\n"
2662                    "write_bytes: %llu\n"
2663                    "cancelled_write_bytes: %llu\n",
2664                    (unsigned long long)acct.rchar,
2665                    (unsigned long long)acct.wchar,
2666                    (unsigned long long)acct.syscr,
2667                    (unsigned long long)acct.syscw,
2668                    (unsigned long long)acct.read_bytes,
2669                    (unsigned long long)acct.write_bytes,
2670                    (unsigned long long)acct.cancelled_write_bytes);
2671         result = 0;
2672
2673 out_unlock:
2674         mutex_unlock(&task->signal->cred_guard_mutex);
2675         return result;
2676 }
2677
2678 static int proc_tid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2679                                   struct pid *pid, struct task_struct *task)
2680 {
2681         return do_io_accounting(task, m, 0);
2682 }
2683
2684 static int proc_tgid_io_accounting(struct seq_file *m, struct pid_namespace *ns,
2685                                    struct pid *pid, struct task_struct *task)
2686 {
2687         return do_io_accounting(task, m, 1);
2688 }
2689 #endif /* CONFIG_TASK_IO_ACCOUNTING */
2690
2691 #ifdef CONFIG_USER_NS
2692 static int proc_id_map_open(struct inode *inode, struct file *file,
2693         const struct seq_operations *seq_ops)
2694 {
2695         struct user_namespace *ns = NULL;
2696         struct task_struct *task;
2697         struct seq_file *seq;
2698         int ret = -EINVAL;
2699
2700         task = get_proc_task(inode);
2701         if (task) {
2702                 rcu_read_lock();
2703                 ns = get_user_ns(task_cred_xxx(task, user_ns));
2704                 rcu_read_unlock();
2705                 put_task_struct(task);
2706         }
2707         if (!ns)
2708                 goto err;
2709
2710         ret = seq_open(file, seq_ops);
2711         if (ret)
2712                 goto err_put_ns;
2713
2714         seq = file->private_data;
2715         seq->private = ns;
2716
2717         return 0;
2718 err_put_ns:
2719         put_user_ns(ns);
2720 err:
2721         return ret;
2722 }
2723
2724 static int proc_id_map_release(struct inode *inode, struct file *file)
2725 {
2726         struct seq_file *seq = file->private_data;
2727         struct user_namespace *ns = seq->private;
2728         put_user_ns(ns);
2729         return seq_release(inode, file);
2730 }
2731
2732 static int proc_uid_map_open(struct inode *inode, struct file *file)
2733 {
2734         return proc_id_map_open(inode, file, &proc_uid_seq_operations);
2735 }
2736
2737 static int proc_gid_map_open(struct inode *inode, struct file *file)
2738 {
2739         return proc_id_map_open(inode, file, &proc_gid_seq_operations);
2740 }
2741
2742 static int proc_projid_map_open(struct inode *inode, struct file *file)
2743 {
2744         return proc_id_map_open(inode, file, &proc_projid_seq_operations);
2745 }
2746
2747 static const struct file_operations proc_uid_map_operations = {
2748         .open           = proc_uid_map_open,
2749         .write          = proc_uid_map_write,
2750         .read           = seq_read,
2751         .llseek         = seq_lseek,
2752         .release        = proc_id_map_release,
2753 };
2754
2755 static const struct file_operations proc_gid_map_operations = {
2756         .open           = proc_gid_map_open,
2757         .write          = proc_gid_map_write,
2758         .read           = seq_read,
2759         .llseek         = seq_lseek,
2760         .release        = proc_id_map_release,
2761 };
2762
2763 static const struct file_operations proc_projid_map_operations = {
2764         .open           = proc_projid_map_open,
2765         .write          = proc_projid_map_write,
2766         .read           = seq_read,
2767         .llseek         = seq_lseek,
2768         .release        = proc_id_map_release,
2769 };
2770
2771 static int proc_setgroups_open(struct inode *inode, struct file *file)
2772 {
2773         struct user_namespace *ns = NULL;
2774         struct task_struct *task;
2775         int ret;
2776
2777         ret = -ESRCH;
2778         task = get_proc_task(inode);
2779         if (task) {
2780                 rcu_read_lock();
2781                 ns = get_user_ns(task_cred_xxx(task, user_ns));
2782                 rcu_read_unlock();
2783                 put_task_struct(task);
2784         }
2785         if (!ns)
2786                 goto err;
2787
2788         if (file->f_mode & FMODE_WRITE) {
2789                 ret = -EACCES;
2790                 if (!ns_capable(ns, CAP_SYS_ADMIN))
2791                         goto err_put_ns;
2792         }
2793
2794         ret = single_open(file, &proc_setgroups_show, ns);
2795         if (ret)
2796                 goto err_put_ns;
2797
2798         return 0;
2799 err_put_ns:
2800         put_user_ns(ns);
2801 err:
2802         return ret;
2803 }
2804
2805 static int proc_setgroups_release(struct inode *inode, struct file *file)
2806 {
2807         struct seq_file *seq = file->private_data;
2808         struct user_namespace *ns = seq->private;
2809         int ret = single_release(inode, file);
2810         put_user_ns(ns);
2811         return ret;
2812 }
2813
2814 static const struct file_operations proc_setgroups_operations = {
2815         .open           = proc_setgroups_open,
2816         .write          = proc_setgroups_write,
2817         .read           = seq_read,
2818         .llseek         = seq_lseek,
2819         .release        = proc_setgroups_release,
2820 };
2821 #endif /* CONFIG_USER_NS */
2822
2823 static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
2824                                 struct pid *pid, struct task_struct *task)
2825 {
2826         int err = lock_trace(task);
2827         if (!err) {
2828                 seq_printf(m, "%08x\n", task->personality);
2829                 unlock_trace(task);
2830         }
2831         return err;
2832 }
2833
2834 #ifdef CONFIG_LIVEPATCH
2835 static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
2836                                 struct pid *pid, struct task_struct *task)
2837 {
2838         seq_printf(m, "%d\n", task->patch_state);
2839         return 0;
2840 }
2841 #endif /* CONFIG_LIVEPATCH */
2842
2843 /*
2844  * Thread groups
2845  */
2846 static const struct file_operations proc_task_operations;
2847 static const struct inode_operations proc_task_inode_operations;
2848
2849 static const struct pid_entry tgid_base_stuff[] = {
2850         DIR("task",       S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations),
2851         DIR("fd",         S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
2852         DIR("map_files",  S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations),
2853         DIR("fdinfo",     S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
2854         DIR("ns",         S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
2855 #ifdef CONFIG_NET
2856         DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
2857 #endif
2858         REG("environ",    S_IRUSR, proc_environ_operations),
2859         REG("auxv",       S_IRUSR, proc_auxv_operations),
2860         ONE("status",     S_IRUGO, proc_pid_status),
2861         ONE("personality", S_IRUSR, proc_pid_personality),
2862         ONE("limits",     S_IRUGO, proc_pid_limits),
2863 #ifdef CONFIG_SCHED_DEBUG
2864         REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),
2865 #endif
2866 #ifdef CONFIG_SCHED_AUTOGROUP
2867         REG("autogroup",  S_IRUGO|S_IWUSR, proc_pid_sched_autogroup_operations),
2868 #endif
2869         REG("comm",      S_IRUGO|S_IWUSR, proc_pid_set_comm_operations),
2870 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
2871         ONE("syscall",    S_IRUSR, proc_pid_syscall),
2872 #endif
2873         REG("cmdline",    S_IRUGO, proc_pid_cmdline_ops),
2874         ONE("stat",       S_IRUGO, proc_tgid_stat),
2875         ONE("statm",      S_IRUGO, proc_pid_statm),
2876         REG("maps",       S_IRUGO, proc_pid_maps_operations),
2877 #ifdef CONFIG_NUMA
2878         REG("numa_maps",  S_IRUGO, proc_pid_numa_maps_operations),
2879 #endif
2880         REG("mem",        S_IRUSR|S_IWUSR, proc_mem_operations),
2881         LNK("cwd",        proc_cwd_link),
2882         LNK("root",       proc_root_link),
2883         LNK("exe",        proc_exe_link),
2884         REG("mounts",     S_IRUGO, proc_mounts_operations),
2885         REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
2886         REG("mountstats", S_IRUSR, proc_mountstats_operations),
2887 #ifdef CONFIG_PROC_PAGE_MONITOR
2888         REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
2889         REG("smaps",      S_IRUGO, proc_pid_smaps_operations),
2890         REG("pagemap",    S_IRUSR, proc_pagemap_operations),
2891 #endif
2892 #ifdef CONFIG_SECURITY
2893         DIR("attr",       S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
2894 #endif
2895 #ifdef CONFIG_KALLSYMS
2896         ONE("wchan",      S_IRUGO, proc_pid_wchan),
2897 #endif
2898 #ifdef CONFIG_STACKTRACE
2899         ONE("stack",      S_IRUSR, proc_pid_stack),
2900 #endif
2901 #ifdef CONFIG_SCHED_INFO
2902         ONE("schedstat",  S_IRUGO, proc_pid_schedstat),
2903 #endif
2904 #ifdef CONFIG_LATENCYTOP
2905         REG("latency",  S_IRUGO, proc_lstats_operations),
2906 #endif
2907 #ifdef CONFIG_PROC_PID_CPUSET
2908         ONE("cpuset",     S_IRUGO, proc_cpuset_show),
2909 #endif
2910 #ifdef CONFIG_CGROUPS
2911         ONE("cgroup",  S_IRUGO, proc_cgroup_show),
2912 #endif
2913         ONE("oom_score",  S_IRUGO, proc_oom_score),
2914         REG("oom_adj",    S_IRUGO|S_IWUSR, proc_oom_adj_operations),
2915         REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
2916 #ifdef CONFIG_AUDITSYSCALL
2917         REG("loginuid",   S_IWUSR|S_IRUGO, proc_loginuid_operations),
2918         REG("sessionid",  S_IRUGO, proc_sessionid_operations),
2919 #endif
2920 #ifdef CONFIG_FAULT_INJECTION
2921         REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
2922 #endif
2923 #ifdef CONFIG_ELF_CORE
2924         REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
2925 #endif
2926 #ifdef CONFIG_TASK_IO_ACCOUNTING
2927         ONE("io",       S_IRUSR, proc_tgid_io_accounting),
2928 #endif
2929 #ifdef CONFIG_HARDWALL
2930         ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
2931 #endif
2932 #ifdef CONFIG_USER_NS
2933         REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
2934         REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
2935         REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
2936         REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
2937 #endif
2938 #if defined(CONFIG_CHECKPOINT_RESTORE) && defined(CONFIG_POSIX_TIMERS)
2939         REG("timers",     S_IRUGO, proc_timers_operations),
2940 #endif
2941         REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
2942 #ifdef CONFIG_LIVEPATCH
2943         ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
2944 #endif
2945 };
2946
2947 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
2948 {
2949         return proc_pident_readdir(file, ctx,
2950                                    tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2951 }
2952
2953 static const struct file_operations proc_tgid_base_operations = {
2954         .read           = generic_read_dir,
2955         .iterate_shared = proc_tgid_base_readdir,
2956         .llseek         = generic_file_llseek,
2957 };
2958
2959 static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
2960 {
2961         return proc_pident_lookup(dir, dentry,
2962                                   tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
2963 }
2964
2965 static const struct inode_operations proc_tgid_base_inode_operations = {
2966         .lookup         = proc_tgid_base_lookup,
2967         .getattr        = pid_getattr,
2968         .setattr        = proc_setattr,
2969         .permission     = proc_pid_permission,
2970 };
2971
2972 static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
2973 {
2974         struct dentry *dentry, *leader, *dir;
2975         char buf[PROC_NUMBUF];
2976         struct qstr name;
2977
2978         name.name = buf;
2979         name.len = snprintf(buf, sizeof(buf), "%d", pid);
2980         /* no ->d_hash() rejects on procfs */
2981         dentry = d_hash_and_lookup(mnt->mnt_root, &name);
2982         if (dentry) {
2983                 d_invalidate(dentry);
2984                 dput(dentry);
2985         }
2986
2987         if (pid == tgid)
2988                 return;
2989
2990         name.name = buf;
2991         name.len = snprintf(buf, sizeof(buf), "%d", tgid);
2992         leader = d_hash_and_lookup(mnt->mnt_root, &name);
2993         if (!leader)
2994                 goto out;
2995
2996         name.name = "task";
2997         name.len = strlen(name.name);
2998         dir = d_hash_and_lookup(leader, &name);
2999         if (!dir)
3000                 goto out_put_leader;
3001
3002         name.name = buf;
3003         name.len = snprintf(buf, sizeof(buf), "%d", pid);
3004         dentry = d_hash_and_lookup(dir, &name);
3005         if (dentry) {
3006                 d_invalidate(dentry);
3007                 dput(dentry);
3008         }
3009
3010         dput(dir);
3011 out_put_leader:
3012         dput(leader);
3013 out:
3014         return;
3015 }
3016
3017 /**
3018  * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
3019  * @task: task that should be flushed.
3020  *
3021  * When flushing dentries from proc, one needs to flush them from global
3022  * proc (proc_mnt) and from all the namespaces' procs this task was seen
3023  * in. This call is supposed to do all of this job.
3024  *
3025  * Looks in the dcache for
3026  * /proc/@pid
3027  * /proc/@tgid/task/@pid
3028  * if either directory is present flushes it and all of it'ts children
3029  * from the dcache.
3030  *
3031  * It is safe and reasonable to cache /proc entries for a task until
3032  * that task exits.  After that they just clog up the dcache with
3033  * useless entries, possibly causing useful dcache entries to be
3034  * flushed instead.  This routine is proved to flush those useless
3035  * dcache entries at process exit time.
3036  *
3037  * NOTE: This routine is just an optimization so it does not guarantee
3038  *       that no dcache entries will exist at process exit time it
3039  *       just makes it very unlikely that any will persist.
3040  */
3041
3042 void proc_flush_task(struct task_struct *task)
3043 {
3044         int i;
3045         struct pid *pid, *tgid;
3046         struct upid *upid;
3047
3048         pid = task_pid(task);
3049         tgid = task_tgid(task);
3050
3051         for (i = 0; i <= pid->level; i++) {
3052                 upid = &pid->numbers[i];
3053                 proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
3054                                         tgid->numbers[i].nr);
3055         }
3056 }
3057
3058 static int proc_pid_instantiate(struct inode *dir,
3059                                    struct dentry * dentry,
3060                                    struct task_struct *task, const void *ptr)
3061 {
3062         struct inode *inode;
3063
3064         inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3065         if (!inode)
3066                 goto out;
3067
3068         inode->i_op = &proc_tgid_base_inode_operations;
3069         inode->i_fop = &proc_tgid_base_operations;
3070         inode->i_flags|=S_IMMUTABLE;
3071
3072         set_nlink(inode, nlink_tgid);
3073
3074         d_set_d_op(dentry, &pid_dentry_operations);
3075
3076         d_add(dentry, inode);
3077         /* Close the race of the process dying before we return the dentry */
3078         if (pid_revalidate(dentry, 0))
3079                 return 0;
3080 out:
3081         return -ENOENT;
3082 }
3083
3084 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3085 {
3086         int result = -ENOENT;
3087         struct task_struct *task;
3088         unsigned tgid;
3089         struct pid_namespace *ns;
3090
3091         tgid = name_to_int(&dentry->d_name);
3092         if (tgid == ~0U)
3093                 goto out;
3094
3095         ns = dentry->d_sb->s_fs_info;
3096         rcu_read_lock();
3097         task = find_task_by_pid_ns(tgid, ns);
3098         if (task)
3099                 get_task_struct(task);
3100         rcu_read_unlock();
3101         if (!task)
3102                 goto out;
3103
3104         result = proc_pid_instantiate(dir, dentry, task, NULL);
3105         put_task_struct(task);
3106 out:
3107         return ERR_PTR(result);
3108 }
3109
3110 /*
3111  * Find the first task with tgid >= tgid
3112  *
3113  */
3114 struct tgid_iter {
3115         unsigned int tgid;
3116         struct task_struct *task;
3117 };
3118 static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
3119 {
3120         struct pid *pid;
3121
3122         if (iter.task)
3123                 put_task_struct(iter.task);
3124         rcu_read_lock();
3125 retry:
3126         iter.task = NULL;
3127         pid = find_ge_pid(iter.tgid, ns);
3128         if (pid) {
3129                 iter.tgid = pid_nr_ns(pid, ns);
3130                 iter.task = pid_task(pid, PIDTYPE_PID);
3131                 /* What we to know is if the pid we have find is the
3132                  * pid of a thread_group_leader.  Testing for task
3133                  * being a thread_group_leader is the obvious thing
3134                  * todo but there is a window when it fails, due to
3135                  * the pid transfer logic in de_thread.
3136                  *
3137                  * So we perform the straight forward test of seeing
3138                  * if the pid we have found is the pid of a thread
3139                  * group leader, and don't worry if the task we have
3140                  * found doesn't happen to be a thread group leader.
3141                  * As we don't care in the case of readdir.
3142                  */
3143                 if (!iter.task || !has_group_leader_pid(iter.task)) {
3144                         iter.tgid += 1;
3145                         goto retry;
3146                 }
3147                 get_task_struct(iter.task);
3148         }
3149         rcu_read_unlock();
3150         return iter;
3151 }
3152
3153 #define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2)
3154
3155 /* for the /proc/ directory itself, after non-process stuff has been done */
3156 int proc_pid_readdir(struct file *file, struct dir_context *ctx)
3157 {
3158         struct tgid_iter iter;
3159         struct pid_namespace *ns = file_inode(file)->i_sb->s_fs_info;
3160         loff_t pos = ctx->pos;
3161
3162         if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
3163                 return 0;
3164
3165         if (pos == TGID_OFFSET - 2) {
3166                 struct inode *inode = d_inode(ns->proc_self);
3167                 if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
3168                         return 0;
3169                 ctx->pos = pos = pos + 1;
3170         }
3171         if (pos == TGID_OFFSET - 1) {
3172                 struct inode *inode = d_inode(ns->proc_thread_self);
3173                 if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
3174                         return 0;
3175                 ctx->pos = pos = pos + 1;
3176         }
3177         iter.tgid = pos - TGID_OFFSET;
3178         iter.task = NULL;
3179         for (iter = next_tgid(ns, iter);
3180              iter.task;
3181              iter.tgid += 1, iter = next_tgid(ns, iter)) {
3182                 char name[PROC_NUMBUF];
3183                 int len;
3184
3185                 cond_resched();
3186                 if (!has_pid_permissions(ns, iter.task, HIDEPID_INVISIBLE))
3187                         continue;
3188
3189                 len = snprintf(name, sizeof(name), "%d", iter.tgid);
3190                 ctx->pos = iter.tgid + TGID_OFFSET;
3191                 if (!proc_fill_cache(file, ctx, name, len,
3192                                      proc_pid_instantiate, iter.task, NULL)) {
3193                         put_task_struct(iter.task);
3194                         return 0;
3195                 }
3196         }
3197         ctx->pos = PID_MAX_LIMIT + TGID_OFFSET;
3198         return 0;
3199 }
3200
3201 /*
3202  * proc_tid_comm_permission is a special permission function exclusively
3203  * used for the node /proc/<pid>/task/<tid>/comm.
3204  * It bypasses generic permission checks in the case where a task of the same
3205  * task group attempts to access the node.
3206  * The rationale behind this is that glibc and bionic access this node for
3207  * cross thread naming (pthread_set/getname_np(!self)). However, if
3208  * PR_SET_DUMPABLE gets set to 0 this node among others becomes uid=0 gid=0,
3209  * which locks out the cross thread naming implementation.
3210  * This function makes sure that the node is always accessible for members of
3211  * same thread group.
3212  */
3213 static int proc_tid_comm_permission(struct inode *inode, int mask)
3214 {
3215         bool is_same_tgroup;
3216         struct task_struct *task;
3217
3218         task = get_proc_task(inode);
3219         if (!task)
3220                 return -ESRCH;
3221         is_same_tgroup = same_thread_group(current, task);
3222         put_task_struct(task);
3223
3224         if (likely(is_same_tgroup && !(mask & MAY_EXEC))) {
3225                 /* This file (/proc/<pid>/task/<tid>/comm) can always be
3226                  * read or written by the members of the corresponding
3227                  * thread group.
3228                  */
3229                 return 0;
3230         }
3231
3232         return generic_permission(inode, mask);
3233 }
3234
3235 static const struct inode_operations proc_tid_comm_inode_operations = {
3236                 .permission = proc_tid_comm_permission,
3237 };
3238
3239 /*
3240  * Tasks
3241  */
3242 static const struct pid_entry tid_base_stuff[] = {
3243         DIR("fd",        S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations),
3244         DIR("fdinfo",    S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations),
3245         DIR("ns",        S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations),
3246 #ifdef CONFIG_NET
3247         DIR("net",        S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations),
3248 #endif
3249         REG("environ",   S_IRUSR, proc_environ_operations),
3250         REG("auxv",      S_IRUSR, proc_auxv_operations),
3251         ONE("status",    S_IRUGO, proc_pid_status),
3252         ONE("personality", S_IRUSR, proc_pid_personality),
3253         ONE("limits",    S_IRUGO, proc_pid_limits),
3254 #ifdef CONFIG_SCHED_DEBUG
3255         REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
3256 #endif
3257         NOD("comm",      S_IFREG|S_IRUGO|S_IWUSR,
3258                          &proc_tid_comm_inode_operations,
3259                          &proc_pid_set_comm_operations, {}),
3260 #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
3261         ONE("syscall",   S_IRUSR, proc_pid_syscall),
3262 #endif
3263         REG("cmdline",   S_IRUGO, proc_pid_cmdline_ops),
3264         ONE("stat",      S_IRUGO, proc_tid_stat),
3265         ONE("statm",     S_IRUGO, proc_pid_statm),
3266         REG("maps",      S_IRUGO, proc_tid_maps_operations),
3267 #ifdef CONFIG_PROC_CHILDREN
3268         REG("children",  S_IRUGO, proc_tid_children_operations),
3269 #endif
3270 #ifdef CONFIG_NUMA
3271         REG("numa_maps", S_IRUGO, proc_tid_numa_maps_operations),
3272 #endif
3273         REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
3274         LNK("cwd",       proc_cwd_link),
3275         LNK("root",      proc_root_link),
3276         LNK("exe",       proc_exe_link),
3277         REG("mounts",    S_IRUGO, proc_mounts_operations),
3278         REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
3279 #ifdef CONFIG_PROC_PAGE_MONITOR
3280         REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
3281         REG("smaps",     S_IRUGO, proc_tid_smaps_operations),
3282         REG("pagemap",    S_IRUSR, proc_pagemap_operations),
3283 #endif
3284 #ifdef CONFIG_SECURITY
3285         DIR("attr",      S_IRUGO|S_IXUGO, proc_attr_dir_inode_operations, proc_attr_dir_operations),
3286 #endif
3287 #ifdef CONFIG_KALLSYMS
3288         ONE("wchan",     S_IRUGO, proc_pid_wchan),
3289 #endif
3290 #ifdef CONFIG_STACKTRACE
3291         ONE("stack",      S_IRUSR, proc_pid_stack),
3292 #endif
3293 #ifdef CONFIG_SCHED_INFO
3294         ONE("schedstat", S_IRUGO, proc_pid_schedstat),
3295 #endif
3296 #ifdef CONFIG_LATENCYTOP
3297         REG("latency",  S_IRUGO, proc_lstats_operations),
3298 #endif
3299 #ifdef CONFIG_PROC_PID_CPUSET
3300         ONE("cpuset",    S_IRUGO, proc_cpuset_show),
3301 #endif
3302 #ifdef CONFIG_CGROUPS
3303         ONE("cgroup",  S_IRUGO, proc_cgroup_show),
3304 #endif
3305         ONE("oom_score", S_IRUGO, proc_oom_score),
3306         REG("oom_adj",   S_IRUGO|S_IWUSR, proc_oom_adj_operations),
3307         REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
3308 #ifdef CONFIG_AUDITSYSCALL
3309         REG("loginuid",  S_IWUSR|S_IRUGO, proc_loginuid_operations),
3310         REG("sessionid",  S_IRUGO, proc_sessionid_operations),
3311 #endif
3312 #ifdef CONFIG_FAULT_INJECTION
3313         REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
3314 #endif
3315 #ifdef CONFIG_TASK_IO_ACCOUNTING
3316         ONE("io",       S_IRUSR, proc_tid_io_accounting),
3317 #endif
3318 #ifdef CONFIG_HARDWALL
3319         ONE("hardwall",   S_IRUGO, proc_pid_hardwall),
3320 #endif
3321 #ifdef CONFIG_USER_NS
3322         REG("uid_map",    S_IRUGO|S_IWUSR, proc_uid_map_operations),
3323         REG("gid_map",    S_IRUGO|S_IWUSR, proc_gid_map_operations),
3324         REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
3325         REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
3326 #endif
3327 #ifdef CONFIG_LIVEPATCH
3328         ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
3329 #endif
3330 };
3331
3332 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
3333 {
3334         return proc_pident_readdir(file, ctx,
3335                                    tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3336 }
3337
3338 static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
3339 {
3340         return proc_pident_lookup(dir, dentry,
3341                                   tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3342 }
3343
3344 static const struct file_operations proc_tid_base_operations = {
3345         .read           = generic_read_dir,
3346         .iterate_shared = proc_tid_base_readdir,
3347         .llseek         = generic_file_llseek,
3348 };
3349
3350 static const struct inode_operations proc_tid_base_inode_operations = {
3351         .lookup         = proc_tid_base_lookup,
3352         .getattr        = pid_getattr,
3353         .setattr        = proc_setattr,
3354 };
3355
3356 static int proc_task_instantiate(struct inode *dir,
3357         struct dentry *dentry, struct task_struct *task, const void *ptr)
3358 {
3359         struct inode *inode;
3360         inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
3361
3362         if (!inode)
3363                 goto out;
3364         inode->i_op = &proc_tid_base_inode_operations;
3365         inode->i_fop = &proc_tid_base_operations;
3366         inode->i_flags|=S_IMMUTABLE;
3367
3368         set_nlink(inode, nlink_tid);
3369
3370         d_set_d_op(dentry, &pid_dentry_operations);
3371
3372         d_add(dentry, inode);
3373         /* Close the race of the process dying before we return the dentry */
3374         if (pid_revalidate(dentry, 0))
3375                 return 0;
3376 out:
3377         return -ENOENT;
3378 }
3379
3380 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
3381 {
3382         int result = -ENOENT;
3383         struct task_struct *task;
3384         struct task_struct *leader = get_proc_task(dir);
3385         unsigned tid;
3386         struct pid_namespace *ns;
3387
3388         if (!leader)
3389                 goto out_no_task;
3390
3391         tid = name_to_int(&dentry->d_name);
3392         if (tid == ~0U)
3393                 goto out;
3394
3395         ns = dentry->d_sb->s_fs_info;
3396         rcu_read_lock();
3397         task = find_task_by_pid_ns(tid, ns);
3398         if (task)
3399                 get_task_struct(task);
3400         rcu_read_unlock();
3401         if (!task)
3402                 goto out;
3403         if (!same_thread_group(leader, task))
3404                 goto out_drop_task;
3405
3406         result = proc_task_instantiate(dir, dentry, task, NULL);
3407 out_drop_task:
3408         put_task_struct(task);
3409 out:
3410         put_task_struct(leader);
3411 out_no_task:
3412         return ERR_PTR(result);
3413 }
3414
3415 /*
3416  * Find the first tid of a thread group to return to user space.
3417  *
3418  * Usually this is just the thread group leader, but if the users
3419  * buffer was too small or there was a seek into the middle of the
3420  * directory we have more work todo.
3421  *
3422  * In the case of a short read we start with find_task_by_pid.
3423  *
3424  * In the case of a seek we start with the leader and walk nr
3425  * threads past it.
3426  */
3427 static struct task_struct *first_tid(struct pid *pid, int tid, loff_t f_pos,
3428                                         struct pid_namespace *ns)
3429 {
3430         struct task_struct *pos, *task;
3431         unsigned long nr = f_pos;
3432
3433         if (nr != f_pos)        /* 32bit overflow? */
3434                 return NULL;
3435
3436         rcu_read_lock();
3437         task = pid_task(pid, PIDTYPE_PID);
3438         if (!task)
3439                 goto fail;
3440
3441         /* Attempt to start with the tid of a thread */
3442         if (tid && nr) {
3443                 pos = find_task_by_pid_ns(tid, ns);
3444                 if (pos && same_thread_group(pos, task))
3445                         goto found;
3446         }
3447
3448         /* If nr exceeds the number of threads there is nothing todo */
3449         if (nr >= get_nr_threads(task))
3450                 goto fail;
3451
3452         /* If we haven't found our starting place yet start
3453          * with the leader and walk nr threads forward.
3454          */
3455         pos = task = task->group_leader;
3456         do {
3457                 if (!nr--)
3458                         goto found;
3459         } while_each_thread(task, pos);
3460 fail:
3461         pos = NULL;
3462         goto out;
3463 found:
3464         get_task_struct(pos);
3465 out:
3466         rcu_read_unlock();
3467         return pos;
3468 }
3469
3470 /*
3471  * Find the next thread in the thread list.
3472  * Return NULL if there is an error or no next thread.
3473  *
3474  * The reference to the input task_struct is released.
3475  */
3476 static struct task_struct *next_tid(struct task_struct *start)
3477 {
3478         struct task_struct *pos = NULL;
3479         rcu_read_lock();
3480         if (pid_alive(start)) {
3481                 pos = next_thread(start);
3482                 if (thread_group_leader(pos))
3483                         pos = NULL;
3484                 else
3485                         get_task_struct(pos);
3486         }
3487         rcu_read_unlock();
3488         put_task_struct(start);
3489         return pos;
3490 }
3491
3492 /* for the /proc/TGID/task/ directories */
3493 static int proc_task_readdir(struct file *file, struct dir_context *ctx)
3494 {
3495         struct inode *inode = file_inode(file);
3496         struct task_struct *task;
3497         struct pid_namespace *ns;
3498         int tid;
3499
3500         if (proc_inode_is_dead(inode))
3501                 return -ENOENT;
3502
3503         if (!dir_emit_dots(file, ctx))
3504                 return 0;
3505
3506         /* f_version caches the tgid value that the last readdir call couldn't
3507          * return. lseek aka telldir automagically resets f_version to 0.
3508          */
3509         ns = inode->i_sb->s_fs_info;
3510         tid = (int)file->f_version;
3511         file->f_version = 0;
3512         for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);
3513              task;
3514              task = next_tid(task), ctx->pos++) {
3515                 char name[PROC_NUMBUF];
3516                 int len;
3517                 tid = task_pid_nr_ns(task, ns);
3518                 len = snprintf(name, sizeof(name), "%d", tid);
3519                 if (!proc_fill_cache(file, ctx, name, len,
3520                                 proc_task_instantiate, task, NULL)) {
3521                         /* returning this tgid failed, save it as the first
3522                          * pid for the next readir call */
3523                         file->f_version = (u64)tid;
3524                         put_task_struct(task);
3525                         break;
3526                 }
3527         }
3528
3529         return 0;
3530 }
3531
3532 static int proc_task_getattr(const struct path *path, struct kstat *stat,
3533                              u32 request_mask, unsigned int query_flags)
3534 {
3535         struct inode *inode = d_inode(path->dentry);
3536         struct task_struct *p = get_proc_task(inode);
3537         generic_fillattr(inode, stat);
3538
3539         if (p) {
3540                 stat->nlink += get_nr_threads(p);
3541                 put_task_struct(p);
3542         }
3543
3544         return 0;
3545 }
3546
3547 static const struct inode_operations proc_task_inode_operations = {
3548         .lookup         = proc_task_lookup,
3549         .getattr        = proc_task_getattr,
3550         .setattr        = proc_setattr,
3551         .permission     = proc_pid_permission,
3552 };
3553
3554 static const struct file_operations proc_task_operations = {
3555         .read           = generic_read_dir,
3556         .iterate_shared = proc_task_readdir,
3557         .llseek         = generic_file_llseek,
3558 };
3559
3560 void __init set_proc_pid_nlink(void)
3561 {
3562         nlink_tid = pid_entry_nlink(tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
3563         nlink_tgid = pid_entry_nlink(tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
3564 }