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