fs/exec.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/exec.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7
   8 /*
   9  * #!-checking implemented by tytso.
  10  */
  11 /*
  12  * Demand-loading implemented 01.12.91 - no need to read anything but
  13  * the header into memory. The inode of the executable is put into
  14  * "current->executable", and page faults do the actual loading. Clean.
  15  *
  16  * Once more I can proudly say that linux stood up to being changed: it
  17  * was less than 2 hours work to get demand-loading completely implemented.
  18  *
  19  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  20  * current->executable is only used by the procfs.  This allows a dispatch
  21  * table to check for several different types  of binary formats.  We keep
  22  * trying until we recognize the file or we run out of supported binary
  23  * formats.
  24  */
  25
  26 #include <linux/slab.h>
  27 #include <linux/file.h>
  28 #include <linux/fdtable.h>
  29 #include <linux/mm.h>
  30 #include <linux/vmacache.h>
  31 #include <linux/stat.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/swap.h>
  34 #include <linux/string.h>
  35 #include <linux/init.h>
  36 #include <linux/sched/mm.h>
  37 #include <linux/sched/coredump.h>
  38 #include <linux/sched/signal.h>
  39 #include <linux/sched/numa_balancing.h>
  40 #include <linux/sched/task.h>
  41 #include <linux/pagemap.h>
  42 #include <linux/perf_event.h>
  43 #include <linux/highmem.h>
  44 #include <linux/spinlock.h>
  45 #include <linux/key.h>
  46 #include <linux/personality.h>
  47 #include <linux/binfmts.h>
  48 #include <linux/utsname.h>
  49 #include <linux/pid_namespace.h>
  50 #include <linux/module.h>
  51 #include <linux/namei.h>
  52 #include <linux/mount.h>
  53 #include <linux/security.h>
  54 #include <linux/syscalls.h>
  55 #include <linux/tsacct_kern.h>
  56 #include <linux/cn_proc.h>
  57 #include <linux/audit.h>
  58 #include <linux/tracehook.h>
  59 #include <linux/kmod.h>
  60 #include <linux/fsnotify.h>
  61 #include <linux/fs_struct.h>
  62 #include <linux/oom.h>
  63 #include <linux/compat.h>
  64 #include <linux/vmalloc.h>
  65 #include <linux/io_uring.h>
  66
  67 #include <linux/uaccess.h>
  68 #include <asm/mmu_context.h>
  69 #include <asm/tlb.h>
  70
  71 #include <trace/events/task.h>
  72 #include "internal.h"
  73
  74 #include <trace/events/sched.h>
  75
  76 static int bprm_creds_from_file(struct linux_binprm *bprm);
  77
  78 int suid_dumpable = 0;
  79
  80 static LIST_HEAD(formats);
  81 static DEFINE_RWLOCK(binfmt_lock);
  82
  83 void __register_binfmt(struct linux_binfmt * fmt, int insert)
  84 {
  85         BUG_ON(!fmt);
  86         if (WARN_ON(!fmt->load_binary))
  87                 return;
  88         write_lock(&binfmt_lock);
  89         insert ? list_add(&fmt->lh, &formats) :
  90                  list_add_tail(&fmt->lh, &formats);
  91         write_unlock(&binfmt_lock);
  92 }
  93
  94 EXPORT_SYMBOL(__register_binfmt);
  95
  96 void unregister_binfmt(struct linux_binfmt * fmt)
  97 {
  98         write_lock(&binfmt_lock);
  99         list_del(&fmt->lh);
 100         write_unlock(&binfmt_lock);
 101 }
 102
 103 EXPORT_SYMBOL(unregister_binfmt);
 104
 105 static inline void put_binfmt(struct linux_binfmt * fmt)
 106 {
 107         module_put(fmt->module);
 108 }
 109
 110 bool path_noexec(const struct path *path)
 111 {
 112         return (path->mnt->mnt_flags & MNT_NOEXEC) ||
 113                (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
 114 }
 115
 116 #ifdef CONFIG_USELIB
 117 /*
 118  * Note that a shared library must be both readable and executable due to
 119  * security reasons.
 120  *
 121  * Also note that we take the address to load from from the file itself.
 122  */
 123 SYSCALL_DEFINE1(uselib, const char __user *, library)
 124 {
 125         struct linux_binfmt *fmt;
 126         struct file *file;
 127         struct filename *tmp = getname(library);
 128         int error = PTR_ERR(tmp);
 129         static const struct open_flags uselib_flags = {
 130                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 131                 .acc_mode = MAY_READ | MAY_EXEC,
 132                 .intent = LOOKUP_OPEN,
 133                 .lookup_flags = LOOKUP_FOLLOW,
 134         };
 135
 136         if (IS_ERR(tmp))
 137                 goto out;
 138
 139         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 140         putname(tmp);
 141         error = PTR_ERR(file);
 142         if (IS_ERR(file))
 143                 goto out;
 144
 145         /*
 146          * may_open() has already checked for this, so it should be
 147          * impossible to trip now. But we need to be extra cautious
 148          * and check again at the very end too.
 149          */
 150         error = -EACCES;
 151         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 152                          path_noexec(&file->f_path)))
 153                 goto exit;
 154
 155         fsnotify_open(file);
 156
 157         error = -ENOEXEC;
 158
 159         read_lock(&binfmt_lock);
 160         list_for_each_entry(fmt, &formats, lh) {
 161                 if (!fmt->load_shlib)
 162                         continue;
 163                 if (!try_module_get(fmt->module))
 164                         continue;
 165                 read_unlock(&binfmt_lock);
 166                 error = fmt->load_shlib(file);
 167                 read_lock(&binfmt_lock);
 168                 put_binfmt(fmt);
 169                 if (error != -ENOEXEC)
 170                         break;
 171         }
 172         read_unlock(&binfmt_lock);
 173 exit:
 174         fput(file);
 175 out:
 176         return error;
 177 }
 178 #endif /* #ifdef CONFIG_USELIB */
 179
 180 #ifdef CONFIG_MMU
 181 /*
 182  * The nascent bprm->mm is not visible until exec_mmap() but it can
 183  * use a lot of memory, account these pages in current->mm temporary
 184  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 185  * change the counter back via acct_arg_size(0).
 186  */
 187 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 188 {
 189         struct mm_struct *mm = current->mm;
 190         long diff = (long)(pages - bprm->vma_pages);
 191
 192         if (!mm || !diff)
 193                 return;
 194
 195         bprm->vma_pages = pages;
 196         add_mm_counter(mm, MM_ANONPAGES, diff);
 197 }
 198
 199 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 200                 int write)
 201 {
 202         struct page *page;
 203         int ret;
 204         unsigned int gup_flags = FOLL_FORCE;
 205
 206 #ifdef CONFIG_STACK_GROWSUP
 207         if (write) {
 208                 ret = expand_downwards(bprm->vma, pos);
 209                 if (ret < 0)
 210                         return NULL;
 211         }
 212 #endif
 213
 214         if (write)
 215                 gup_flags |= FOLL_WRITE;
 216
 217         /*
 218          * We are doing an exec().  'current' is the process
 219          * doing the exec and bprm->mm is the new process's mm.
 220          */
 221         ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
 222                         &page, NULL, NULL);
 223         if (ret <= 0)
 224                 return NULL;
 225
 226         if (write)
 227                 acct_arg_size(bprm, vma_pages(bprm->vma));
 228
 229         return page;
 230 }
 231
 232 static void put_arg_page(struct page *page)
 233 {
 234         put_page(page);
 235 }
 236
 237 static void free_arg_pages(struct linux_binprm *bprm)
 238 {
 239 }
 240
 241 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 242                 struct page *page)
 243 {
 244         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 245 }
 246
 247 static int __bprm_mm_init(struct linux_binprm *bprm)
 248 {
 249         int err;
 250         struct vm_area_struct *vma = NULL;
 251         struct mm_struct *mm = bprm->mm;
 252
 253         bprm->vma = vma = vm_area_alloc(mm);
 254         if (!vma)
 255                 return -ENOMEM;
 256         vma_set_anonymous(vma);
 257
 258         if (mmap_write_lock_killable(mm)) {
 259                 err = -EINTR;
 260                 goto err_free;
 261         }
 262
 263         /*
 264          * Place the stack at the largest stack address the architecture
 265          * supports. Later, we'll move this to an appropriate place. We don't
 266          * use STACK_TOP because that can depend on attributes which aren't
 267          * configured yet.
 268          */
 269         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 270         vma->vm_end = STACK_TOP_MAX;
 271         vma->vm_start = vma->vm_end - PAGE_SIZE;
 272         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 273         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 274
 275         err = insert_vm_struct(mm, vma);
 276         if (err)
 277                 goto err;
 278
 279         mm->stack_vm = mm->total_vm = 1;
 280         mmap_write_unlock(mm);
 281         bprm->p = vma->vm_end - sizeof(void *);
 282         return 0;
 283 err:
 284         mmap_write_unlock(mm);
 285 err_free:
 286         bprm->vma = NULL;
 287         vm_area_free(vma);
 288         return err;
 289 }
 290
 291 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 292 {
 293         return len <= MAX_ARG_STRLEN;
 294 }
 295
 296 #else
 297
 298 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 299 {
 300 }
 301
 302 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 303                 int write)
 304 {
 305         struct page *page;
 306
 307         page = bprm->page[pos / PAGE_SIZE];
 308         if (!page && write) {
 309                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 310                 if (!page)
 311                         return NULL;
 312                 bprm->page[pos / PAGE_SIZE] = page;
 313         }
 314
 315         return page;
 316 }
 317
 318 static void put_arg_page(struct page *page)
 319 {
 320 }
 321
 322 static void free_arg_page(struct linux_binprm *bprm, int i)
 323 {
 324         if (bprm->page[i]) {
 325                 __free_page(bprm->page[i]);
 326                 bprm->page[i] = NULL;
 327         }
 328 }
 329
 330 static void free_arg_pages(struct linux_binprm *bprm)
 331 {
 332         int i;
 333
 334         for (i = 0; i < MAX_ARG_PAGES; i++)
 335                 free_arg_page(bprm, i);
 336 }
 337
 338 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 339                 struct page *page)
 340 {
 341 }
 342
 343 static int __bprm_mm_init(struct linux_binprm *bprm)
 344 {
 345         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 346         return 0;
 347 }
 348
 349 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 350 {
 351         return len <= bprm->p;
 352 }
 353
 354 #endif /* CONFIG_MMU */
 355
 356 /*
 357  * Create a new mm_struct and populate it with a temporary stack
 358  * vm_area_struct.  We don't have enough context at this point to set the stack
 359  * flags, permissions, and offset, so we use temporary values.  We'll update
 360  * them later in setup_arg_pages().
 361  */
 362 static int bprm_mm_init(struct linux_binprm *bprm)
 363 {
 364         int err;
 365         struct mm_struct *mm = NULL;
 366
 367         bprm->mm = mm = mm_alloc();
 368         err = -ENOMEM;
 369         if (!mm)
 370                 goto err;
 371
 372         /* Save current stack limit for all calculations made during exec. */
 373         task_lock(current->group_leader);
 374         bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
 375         task_unlock(current->group_leader);
 376
 377         err = __bprm_mm_init(bprm);
 378         if (err)
 379                 goto err;
 380
 381         return 0;
 382
 383 err:
 384         if (mm) {
 385                 bprm->mm = NULL;
 386                 mmdrop(mm);
 387         }
 388
 389         return err;
 390 }
 391
 392 struct user_arg_ptr {
 393 #ifdef CONFIG_COMPAT
 394         bool is_compat;
 395 #endif
 396         union {
 397                 const char __user *const __user *native;
 398 #ifdef CONFIG_COMPAT
 399                 const compat_uptr_t __user *compat;
 400 #endif
 401         } ptr;
 402 };
 403
 404 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 405 {
 406         const char __user *native;
 407
 408 #ifdef CONFIG_COMPAT
 409         if (unlikely(argv.is_compat)) {
 410                 compat_uptr_t compat;
 411
 412                 if (get_user(compat, argv.ptr.compat + nr))
 413                         return ERR_PTR(-EFAULT);
 414
 415                 return compat_ptr(compat);
 416         }
 417 #endif
 418
 419         if (get_user(native, argv.ptr.native + nr))
 420                 return ERR_PTR(-EFAULT);
 421
 422         return native;
 423 }
 424
 425 /*
 426  * count() counts the number of strings in array ARGV.
 427  */
 428 static int count(struct user_arg_ptr argv, int max)
 429 {
 430         int i = 0;
 431
 432         if (argv.ptr.native != NULL) {
 433                 for (;;) {
 434                         const char __user *p = get_user_arg_ptr(argv, i);
 435
 436                         if (!p)
 437                                 break;
 438
 439                         if (IS_ERR(p))
 440                                 return -EFAULT;
 441
 442                         if (i >= max)
 443                                 return -E2BIG;
 444                         ++i;
 445
 446                         if (fatal_signal_pending(current))
 447                                 return -ERESTARTNOHAND;
 448                         cond_resched();
 449                 }
 450         }
 451         return i;
 452 }
 453
 454 static int count_strings_kernel(const char *const *argv)
 455 {
 456         int i;
 457
 458         if (!argv)
 459                 return 0;
 460
 461         for (i = 0; argv[i]; ++i) {
 462                 if (i >= MAX_ARG_STRINGS)
 463                         return -E2BIG;
 464                 if (fatal_signal_pending(current))
 465                         return -ERESTARTNOHAND;
 466                 cond_resched();
 467         }
 468         return i;
 469 }
 470
 471 static int bprm_stack_limits(struct linux_binprm *bprm)
 472 {
 473         unsigned long limit, ptr_size;
 474
 475         /*
 476          * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
 477          * (whichever is smaller) for the argv+env strings.
 478          * This ensures that:
 479          *  - the remaining binfmt code will not run out of stack space,
 480          *  - the program will have a reasonable amount of stack left
 481          *    to work from.
 482          */
 483         limit = _STK_LIM / 4 * 3;
 484         limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
 485         /*
 486          * We've historically supported up to 32 pages (ARG_MAX)
 487          * of argument strings even with small stacks
 488          */
 489         limit = max_t(unsigned long, limit, ARG_MAX);
 490         /*
 491          * We must account for the size of all the argv and envp pointers to
 492          * the argv and envp strings, since they will also take up space in
 493          * the stack. They aren't stored until much later when we can't
 494          * signal to the parent that the child has run out of stack space.
 495          * Instead, calculate it here so it's possible to fail gracefully.
 496          */
 497         ptr_size = (bprm->argc + bprm->envc) * sizeof(void *);
 498         if (limit <= ptr_size)
 499                 return -E2BIG;
 500         limit -= ptr_size;
 501
 502         bprm->argmin = bprm->p - limit;
 503         return 0;
 504 }
 505
 506 /*
 507  * 'copy_strings()' copies argument/environment strings from the old
 508  * processes's memory to the new process's stack.  The call to get_user_pages()
 509  * ensures the destination page is created and not swapped out.
 510  */
 511 static int copy_strings(int argc, struct user_arg_ptr argv,
 512                         struct linux_binprm *bprm)
 513 {
 514         struct page *kmapped_page = NULL;
 515         char *kaddr = NULL;
 516         unsigned long kpos = 0;
 517         int ret;
 518
 519         while (argc-- > 0) {
 520                 const char __user *str;
 521                 int len;
 522                 unsigned long pos;
 523
 524                 ret = -EFAULT;
 525                 str = get_user_arg_ptr(argv, argc);
 526                 if (IS_ERR(str))
 527                         goto out;
 528
 529                 len = strnlen_user(str, MAX_ARG_STRLEN);
 530                 if (!len)
 531                         goto out;
 532
 533                 ret = -E2BIG;
 534                 if (!valid_arg_len(bprm, len))
 535                         goto out;
 536
 537                 /* We're going to work our way backwords. */
 538                 pos = bprm->p;
 539                 str += len;
 540                 bprm->p -= len;
 541 #ifdef CONFIG_MMU
 542                 if (bprm->p < bprm->argmin)
 543                         goto out;
 544 #endif
 545
 546                 while (len > 0) {
 547                         int offset, bytes_to_copy;
 548
 549                         if (fatal_signal_pending(current)) {
 550                                 ret = -ERESTARTNOHAND;
 551                                 goto out;
 552                         }
 553                         cond_resched();
 554
 555                         offset = pos % PAGE_SIZE;
 556                         if (offset == 0)
 557                                 offset = PAGE_SIZE;
 558
 559                         bytes_to_copy = offset;
 560                         if (bytes_to_copy > len)
 561                                 bytes_to_copy = len;
 562
 563                         offset -= bytes_to_copy;
 564                         pos -= bytes_to_copy;
 565                         str -= bytes_to_copy;
 566                         len -= bytes_to_copy;
 567
 568                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 569                                 struct page *page;
 570
 571                                 page = get_arg_page(bprm, pos, 1);
 572                                 if (!page) {
 573                                         ret = -E2BIG;
 574                                         goto out;
 575                                 }
 576
 577                                 if (kmapped_page) {
 578                                         flush_kernel_dcache_page(kmapped_page);
 579                                         kunmap(kmapped_page);
 580                                         put_arg_page(kmapped_page);
 581                                 }
 582                                 kmapped_page = page;
 583                                 kaddr = kmap(kmapped_page);
 584                                 kpos = pos & PAGE_MASK;
 585                                 flush_arg_page(bprm, kpos, kmapped_page);
 586                         }
 587                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 588                                 ret = -EFAULT;
 589                                 goto out;
 590                         }
 591                 }
 592         }
 593         ret = 0;
 594 out:
 595         if (kmapped_page) {
 596                 flush_kernel_dcache_page(kmapped_page);
 597                 kunmap(kmapped_page);
 598                 put_arg_page(kmapped_page);
 599         }
 600         return ret;
 601 }
 602
 603 /*
 604  * Copy and argument/environment string from the kernel to the processes stack.
 605  */
 606 int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
 607 {
 608         int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
 609         unsigned long pos = bprm->p;
 610
 611         if (len == 0)
 612                 return -EFAULT;
 613         if (!valid_arg_len(bprm, len))
 614                 return -E2BIG;
 615
 616         /* We're going to work our way backwards. */
 617         arg += len;
 618         bprm->p -= len;
 619         if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
 620                 return -E2BIG;
 621
 622         while (len > 0) {
 623                 unsigned int bytes_to_copy = min_t(unsigned int, len,
 624                                 min_not_zero(offset_in_page(pos), PAGE_SIZE));
 625                 struct page *page;
 626                 char *kaddr;
 627
 628                 pos -= bytes_to_copy;
 629                 arg -= bytes_to_copy;
 630                 len -= bytes_to_copy;
 631
 632                 page = get_arg_page(bprm, pos, 1);
 633                 if (!page)
 634                         return -E2BIG;
 635                 kaddr = kmap_atomic(page);
 636                 flush_arg_page(bprm, pos & PAGE_MASK, page);
 637                 memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy);
 638                 flush_kernel_dcache_page(page);
 639                 kunmap_atomic(kaddr);
 640                 put_arg_page(page);
 641         }
 642
 643         return 0;
 644 }
 645 EXPORT_SYMBOL(copy_string_kernel);
 646
 647 static int copy_strings_kernel(int argc, const char *const *argv,
 648                                struct linux_binprm *bprm)
 649 {
 650         while (argc-- > 0) {
 651                 int ret = copy_string_kernel(argv[argc], bprm);
 652                 if (ret < 0)
 653                         return ret;
 654                 if (fatal_signal_pending(current))
 655                         return -ERESTARTNOHAND;
 656                 cond_resched();
 657         }
 658         return 0;
 659 }
 660
 661 #ifdef CONFIG_MMU
 662
 663 /*
 664  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 665  * the binfmt code determines where the new stack should reside, we shift it to
 666  * its final location.  The process proceeds as follows:
 667  *
 668  * 1) Use shift to calculate the new vma endpoints.
 669  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 670  *    arguments passed to subsequent functions are consistent.
 671  * 3) Move vma's page tables to the new range.
 672  * 4) Free up any cleared pgd range.
 673  * 5) Shrink the vma to cover only the new range.
 674  */
 675 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 676 {
 677         struct mm_struct *mm = vma->vm_mm;
 678         unsigned long old_start = vma->vm_start;
 679         unsigned long old_end = vma->vm_end;
 680         unsigned long length = old_end - old_start;
 681         unsigned long new_start = old_start - shift;
 682         unsigned long new_end = old_end - shift;
 683         struct mmu_gather tlb;
 684
 685         BUG_ON(new_start > new_end);
 686
 687         /*
 688          * ensure there are no vmas between where we want to go
 689          * and where we are
 690          */
 691         if (vma != find_vma(mm, new_start))
 692                 return -EFAULT;
 693
 694         /*
 695          * cover the whole range: [new_start, old_end)
 696          */
 697         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 698                 return -ENOMEM;
 699
 700         /*
 701          * move the page tables downwards, on failure we rely on
 702          * process cleanup to remove whatever mess we made.
 703          */
 704         if (length != move_page_tables(vma, old_start,
 705                                        vma, new_start, length, false))
 706                 return -ENOMEM;
 707
 708         lru_add_drain();
 709         tlb_gather_mmu(&tlb, mm, old_start, old_end);
 710         if (new_end > old_start) {
 711                 /*
 712                  * when the old and new regions overlap clear from new_end.
 713                  */
 714                 free_pgd_range(&tlb, new_end, old_end, new_end,
 715                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 716         } else {
 717                 /*
 718                  * otherwise, clean from old_start; this is done to not touch
 719                  * the address space in [new_end, old_start) some architectures
 720                  * have constraints on va-space that make this illegal (IA64) -
 721                  * for the others its just a little faster.
 722                  */
 723                 free_pgd_range(&tlb, old_start, old_end, new_end,
 724                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 725         }
 726         tlb_finish_mmu(&tlb, old_start, old_end);
 727
 728         /*
 729          * Shrink the vma to just the new range.  Always succeeds.
 730          */
 731         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 732
 733         return 0;
 734 }
 735
 736 /*
 737  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 738  * the stack is optionally relocated, and some extra space is added.
 739  */
 740 int setup_arg_pages(struct linux_binprm *bprm,
 741                     unsigned long stack_top,
 742                     int executable_stack)
 743 {
 744         unsigned long ret;
 745         unsigned long stack_shift;
 746         struct mm_struct *mm = current->mm;
 747         struct vm_area_struct *vma = bprm->vma;
 748         struct vm_area_struct *prev = NULL;
 749         unsigned long vm_flags;
 750         unsigned long stack_base;
 751         unsigned long stack_size;
 752         unsigned long stack_expand;
 753         unsigned long rlim_stack;
 754
 755 #ifdef CONFIG_STACK_GROWSUP
 756         /* Limit stack size */
 757         stack_base = bprm->rlim_stack.rlim_max;
 758         if (stack_base > STACK_SIZE_MAX)
 759                 stack_base = STACK_SIZE_MAX;
 760
 761         /* Add space for stack randomization. */
 762         stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 763
 764         /* Make sure we didn't let the argument array grow too large. */
 765         if (vma->vm_end - vma->vm_start > stack_base)
 766                 return -ENOMEM;
 767
 768         stack_base = PAGE_ALIGN(stack_top - stack_base);
 769
 770         stack_shift = vma->vm_start - stack_base;
 771         mm->arg_start = bprm->p - stack_shift;
 772         bprm->p = vma->vm_end - stack_shift;
 773 #else
 774         stack_top = arch_align_stack(stack_top);
 775         stack_top = PAGE_ALIGN(stack_top);
 776
 777         if (unlikely(stack_top < mmap_min_addr) ||
 778             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 779                 return -ENOMEM;
 780
 781         stack_shift = vma->vm_end - stack_top;
 782
 783         bprm->p -= stack_shift;
 784         mm->arg_start = bprm->p;
 785 #endif
 786
 787         if (bprm->loader)
 788                 bprm->loader -= stack_shift;
 789         bprm->exec -= stack_shift;
 790
 791         if (mmap_write_lock_killable(mm))
 792                 return -EINTR;
 793
 794         vm_flags = VM_STACK_FLAGS;
 795
 796         /*
 797          * Adjust stack execute permissions; explicitly enable for
 798          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 799          * (arch default) otherwise.
 800          */
 801         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 802                 vm_flags |= VM_EXEC;
 803         else if (executable_stack == EXSTACK_DISABLE_X)
 804                 vm_flags &= ~VM_EXEC;
 805         vm_flags |= mm->def_flags;
 806         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 807
 808         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 809                         vm_flags);
 810         if (ret)
 811                 goto out_unlock;
 812         BUG_ON(prev != vma);
 813
 814         if (unlikely(vm_flags & VM_EXEC)) {
 815                 pr_warn_once("process '%pD4' started with executable stack\n",
 816                              bprm->file);
 817         }
 818
 819         /* Move stack pages down in memory. */
 820         if (stack_shift) {
 821                 ret = shift_arg_pages(vma, stack_shift);
 822                 if (ret)
 823                         goto out_unlock;
 824         }
 825
 826         /* mprotect_fixup is overkill to remove the temporary stack flags */
 827         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 828
 829         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 830         stack_size = vma->vm_end - vma->vm_start;
 831         /*
 832          * Align this down to a page boundary as expand_stack
 833          * will align it up.
 834          */
 835         rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
 836 #ifdef CONFIG_STACK_GROWSUP
 837         if (stack_size + stack_expand > rlim_stack)
 838                 stack_base = vma->vm_start + rlim_stack;
 839         else
 840                 stack_base = vma->vm_end + stack_expand;
 841 #else
 842         if (stack_size + stack_expand > rlim_stack)
 843                 stack_base = vma->vm_end - rlim_stack;
 844         else
 845                 stack_base = vma->vm_start - stack_expand;
 846 #endif
 847         current->mm->start_stack = bprm->p;
 848         ret = expand_stack(vma, stack_base);
 849         if (ret)
 850                 ret = -EFAULT;
 851
 852 out_unlock:
 853         mmap_write_unlock(mm);
 854         return ret;
 855 }
 856 EXPORT_SYMBOL(setup_arg_pages);
 857
 858 #else
 859
 860 /*
 861  * Transfer the program arguments and environment from the holding pages
 862  * onto the stack. The provided stack pointer is adjusted accordingly.
 863  */
 864 int transfer_args_to_stack(struct linux_binprm *bprm,
 865                            unsigned long *sp_location)
 866 {
 867         unsigned long index, stop, sp;
 868         int ret = 0;
 869
 870         stop = bprm->p >> PAGE_SHIFT;
 871         sp = *sp_location;
 872
 873         for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
 874                 unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
 875                 char *src = kmap(bprm->page[index]) + offset;
 876                 sp -= PAGE_SIZE - offset;
 877                 if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
 878                         ret = -EFAULT;
 879                 kunmap(bprm->page[index]);
 880                 if (ret)
 881                         goto out;
 882         }
 883
 884         *sp_location = sp;
 885
 886 out:
 887         return ret;
 888 }
 889 EXPORT_SYMBOL(transfer_args_to_stack);
 890
 891 #endif /* CONFIG_MMU */
 892
 893 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 894 {
 895         struct file *file;
 896         int err;
 897         struct open_flags open_exec_flags = {
 898                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 899                 .acc_mode = MAY_EXEC,
 900                 .intent = LOOKUP_OPEN,
 901                 .lookup_flags = LOOKUP_FOLLOW,
 902         };
 903
 904         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 905                 return ERR_PTR(-EINVAL);
 906         if (flags & AT_SYMLINK_NOFOLLOW)
 907                 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 908         if (flags & AT_EMPTY_PATH)
 909                 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 910
 911         file = do_filp_open(fd, name, &open_exec_flags);
 912         if (IS_ERR(file))
 913                 goto out;
 914
 915         /*
 916          * may_open() has already checked for this, so it should be
 917          * impossible to trip now. But we need to be extra cautious
 918          * and check again at the very end too.
 919          */
 920         err = -EACCES;
 921         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 922                          path_noexec(&file->f_path)))
 923                 goto exit;
 924
 925         err = deny_write_access(file);
 926         if (err)
 927                 goto exit;
 928
 929         if (name->name[0] != '\0')
 930                 fsnotify_open(file);
 931
 932 out:
 933         return file;
 934
 935 exit:
 936         fput(file);
 937         return ERR_PTR(err);
 938 }
 939
 940 struct file *open_exec(const char *name)
 941 {
 942         struct filename *filename = getname_kernel(name);
 943         struct file *f = ERR_CAST(filename);
 944
 945         if (!IS_ERR(filename)) {
 946                 f = do_open_execat(AT_FDCWD, filename, 0);
 947                 putname(filename);
 948         }
 949         return f;
 950 }
 951 EXPORT_SYMBOL(open_exec);
 952
 953 int kernel_read_file(struct file *file, void **buf, loff_t *size,
 954                      loff_t max_size, enum kernel_read_file_id id)
 955 {
 956         loff_t i_size, pos;
 957         ssize_t bytes = 0;
 958         int ret;
 959
 960         if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
 961                 return -EINVAL;
 962
 963         ret = deny_write_access(file);
 964         if (ret)
 965                 return ret;
 966
 967         ret = security_kernel_read_file(file, id);
 968         if (ret)
 969                 goto out;
 970
 971         i_size = i_size_read(file_inode(file));
 972         if (i_size <= 0) {
 973                 ret = -EINVAL;
 974                 goto out;
 975         }
 976         if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
 977                 ret = -EFBIG;
 978                 goto out;
 979         }
 980
 981         if (id != READING_FIRMWARE_PREALLOC_BUFFER)
 982                 *buf = vmalloc(i_size);
 983         if (!*buf) {
 984                 ret = -ENOMEM;
 985                 goto out;
 986         }
 987
 988         pos = 0;
 989         while (pos < i_size) {
 990                 bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
 991                 if (bytes < 0) {
 992                         ret = bytes;
 993                         goto out_free;
 994                 }
 995
 996                 if (bytes == 0)
 997                         break;
 998         }
 999
1000         if (pos != i_size) {
1001                 ret = -EIO;
1002                 goto out_free;
1003         }
1004
1005         ret = security_kernel_post_read_file(file, *buf, i_size, id);
1006         if (!ret)
1007                 *size = pos;
1008
1009 out_free:
1010         if (ret < 0) {
1011                 if (id != READING_FIRMWARE_PREALLOC_BUFFER) {
1012                         vfree(*buf);
1013                         *buf = NULL;
1014                 }
1015         }
1016
1017 out:
1018         allow_write_access(file);
1019         return ret;
1020 }
1021 EXPORT_SYMBOL_GPL(kernel_read_file);
1022
1023 int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
1024                                loff_t max_size, enum kernel_read_file_id id)
1025 {
1026         struct file *file;
1027         int ret;
1028
1029         if (!path || !*path)
1030                 return -EINVAL;
1031
1032         file = filp_open(path, O_RDONLY, 0);
1033         if (IS_ERR(file))
1034                 return PTR_ERR(file);
1035
1036         ret = kernel_read_file(file, buf, size, max_size, id);
1037         fput(file);
1038         return ret;
1039 }
1040 EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
1041
1042 int kernel_read_file_from_path_initns(const char *path, void **buf,
1043                                       loff_t *size, loff_t max_size,
1044                                       enum kernel_read_file_id id)
1045 {
1046         struct file *file;
1047         struct path root;
1048         int ret;
1049
1050         if (!path || !*path)
1051                 return -EINVAL;
1052
1053         task_lock(&init_task);
1054         get_fs_root(init_task.fs, &root);
1055         task_unlock(&init_task);
1056
1057         file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
1058         path_put(&root);
1059         if (IS_ERR(file))
1060                 return PTR_ERR(file);
1061
1062         ret = kernel_read_file(file, buf, size, max_size, id);
1063         fput(file);
1064         return ret;
1065 }
1066 EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
1067
1068 int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
1069                              enum kernel_read_file_id id)
1070 {
1071         struct fd f = fdget(fd);
1072         int ret = -EBADF;
1073
1074         if (!f.file)
1075                 goto out;
1076
1077         ret = kernel_read_file(f.file, buf, size, max_size, id);
1078 out:
1079         fdput(f);
1080         return ret;
1081 }
1082 EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
1083
1084 #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
1085     defined(CONFIG_BINFMT_ELF_FDPIC)
1086 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
1087 {
1088         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
1089         if (res > 0)
1090                 flush_icache_user_range(addr, addr + len);
1091         return res;
1092 }
1093 EXPORT_SYMBOL(read_code);
1094 #endif
1095
1096 /*
1097  * Maps the mm_struct mm into the current task struct.
1098  * On success, this function returns with the mutex
1099  * exec_update_mutex locked.
1100  */
1101 static int exec_mmap(struct mm_struct *mm)
1102 {
1103         struct task_struct *tsk;
1104         struct mm_struct *old_mm, *active_mm;
1105         int ret;
1106
1107         /* Notify parent that we're no longer interested in the old VM */
1108         tsk = current;
1109         old_mm = current->mm;
1110         exec_mm_release(tsk, old_mm);
1111         if (old_mm)
1112                 sync_mm_rss(old_mm);
1113
1114         ret = mutex_lock_killable(&tsk->signal->exec_update_mutex);
1115         if (ret)
1116                 return ret;
1117
1118         if (old_mm) {
1119                 /*
1120                  * Make sure that if there is a core dump in progress
1121                  * for the old mm, we get out and die instead of going
1122                  * through with the exec.  We must hold mmap_lock around
1123                  * checking core_state and changing tsk->mm.
1124                  */
1125                 mmap_read_lock(old_mm);
1126                 if (unlikely(old_mm->core_state)) {
1127                         mmap_read_unlock(old_mm);
1128                         mutex_unlock(&tsk->signal->exec_update_mutex);
1129                         return -EINTR;
1130                 }
1131         }
1132
1133         task_lock(tsk);
1134         active_mm = tsk->active_mm;
1135         membarrier_exec_mmap(mm);
1136         tsk->mm = mm;
1137         tsk->active_mm = mm;
1138         activate_mm(active_mm, mm);
1139         tsk->mm->vmacache_seqnum = 0;
1140         vmacache_flush(tsk);
1141         task_unlock(tsk);
1142         if (old_mm) {
1143                 mmap_read_unlock(old_mm);
1144                 BUG_ON(active_mm != old_mm);
1145                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1146                 mm_update_next_owner(old_mm);
1147                 mmput(old_mm);
1148                 return 0;
1149         }
1150         mmdrop(active_mm);
1151         return 0;
1152 }
1153
1154 static int de_thread(struct task_struct *tsk)
1155 {
1156         struct signal_struct *sig = tsk->signal;
1157         struct sighand_struct *oldsighand = tsk->sighand;
1158         spinlock_t *lock = &oldsighand->siglock;
1159
1160         if (thread_group_empty(tsk))
1161                 goto no_thread_group;
1162
1163         /*
1164          * Kill all other threads in the thread group.
1165          */
1166         spin_lock_irq(lock);
1167         if (signal_group_exit(sig)) {
1168                 /*
1169                  * Another group action in progress, just
1170                  * return so that the signal is processed.
1171                  */
1172                 spin_unlock_irq(lock);
1173                 return -EAGAIN;
1174         }
1175
1176         sig->group_exit_task = tsk;
1177         sig->notify_count = zap_other_threads(tsk);
1178         if (!thread_group_leader(tsk))
1179                 sig->notify_count--;
1180
1181         while (sig->notify_count) {
1182                 __set_current_state(TASK_KILLABLE);
1183                 spin_unlock_irq(lock);
1184                 schedule();
1185                 if (__fatal_signal_pending(tsk))
1186                         goto killed;
1187                 spin_lock_irq(lock);
1188         }
1189         spin_unlock_irq(lock);
1190
1191         /*
1192          * At this point all other threads have exited, all we have to
1193          * do is to wait for the thread group leader to become inactive,
1194          * and to assume its PID:
1195          */
1196         if (!thread_group_leader(tsk)) {
1197                 struct task_struct *leader = tsk->group_leader;
1198
1199                 for (;;) {
1200                         cgroup_threadgroup_change_begin(tsk);
1201                         write_lock_irq(&tasklist_lock);
1202                         /*
1203                          * Do this under tasklist_lock to ensure that
1204                          * exit_notify() can't miss ->group_exit_task
1205                          */
1206                         sig->notify_count = -1;
1207                         if (likely(leader->exit_state))
1208                                 break;
1209                         __set_current_state(TASK_KILLABLE);
1210                         write_unlock_irq(&tasklist_lock);
1211                         cgroup_threadgroup_change_end(tsk);
1212                         schedule();
1213                         if (__fatal_signal_pending(tsk))
1214                                 goto killed;
1215                 }
1216
1217                 /*
1218                  * The only record we have of the real-time age of a
1219                  * process, regardless of execs it's done, is start_time.
1220                  * All the past CPU time is accumulated in signal_struct
1221                  * from sister threads now dead.  But in this non-leader
1222                  * exec, nothing survives from the original leader thread,
1223                  * whose birth marks the true age of this process now.
1224                  * When we take on its identity by switching to its PID, we
1225                  * also take its birthdate (always earlier than our own).
1226                  */
1227                 tsk->start_time = leader->start_time;
1228                 tsk->start_boottime = leader->start_boottime;
1229
1230                 BUG_ON(!same_thread_group(leader, tsk));
1231                 /*
1232                  * An exec() starts a new thread group with the
1233                  * TGID of the previous thread group. Rehash the
1234                  * two threads with a switched PID, and release
1235                  * the former thread group leader:
1236                  */
1237
1238                 /* Become a process group leader with the old leader's pid.
1239                  * The old leader becomes a thread of the this thread group.
1240                  */
1241                 exchange_tids(tsk, leader);
1242                 transfer_pid(leader, tsk, PIDTYPE_TGID);
1243                 transfer_pid(leader, tsk, PIDTYPE_PGID);
1244                 transfer_pid(leader, tsk, PIDTYPE_SID);
1245
1246                 list_replace_rcu(&leader->tasks, &tsk->tasks);
1247                 list_replace_init(&leader->sibling, &tsk->sibling);
1248
1249                 tsk->group_leader = tsk;
1250                 leader->group_leader = tsk;
1251
1252                 tsk->exit_signal = SIGCHLD;
1253                 leader->exit_signal = -1;
1254
1255                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1256                 leader->exit_state = EXIT_DEAD;
1257
1258                 /*
1259                  * We are going to release_task()->ptrace_unlink() silently,
1260                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1261                  * the tracer wont't block again waiting for this thread.
1262                  */
1263                 if (unlikely(leader->ptrace))
1264                         __wake_up_parent(leader, leader->parent);
1265                 write_unlock_irq(&tasklist_lock);
1266                 cgroup_threadgroup_change_end(tsk);
1267
1268                 release_task(leader);
1269         }
1270
1271         sig->group_exit_task = NULL;
1272         sig->notify_count = 0;
1273
1274 no_thread_group:
1275         /* we have changed execution domain */
1276         tsk->exit_signal = SIGCHLD;
1277
1278         BUG_ON(!thread_group_leader(tsk));
1279         return 0;
1280
1281 killed:
1282         /* protects against exit_notify() and __exit_signal() */
1283         read_lock(&tasklist_lock);
1284         sig->group_exit_task = NULL;
1285         sig->notify_count = 0;
1286         read_unlock(&tasklist_lock);
1287         return -EAGAIN;
1288 }
1289
1290
1291 /*
1292  * This function makes sure the current process has its own signal table,
1293  * so that flush_signal_handlers can later reset the handlers without
1294  * disturbing other processes.  (Other processes might share the signal
1295  * table via the CLONE_SIGHAND option to clone().)
1296  */
1297 static int unshare_sighand(struct task_struct *me)
1298 {
1299         struct sighand_struct *oldsighand = me->sighand;
1300
1301         if (refcount_read(&oldsighand->count) != 1) {
1302                 struct sighand_struct *newsighand;
1303                 /*
1304                  * This ->sighand is shared with the CLONE_SIGHAND
1305                  * but not CLONE_THREAD task, switch to the new one.
1306                  */
1307                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1308                 if (!newsighand)
1309                         return -ENOMEM;
1310
1311                 refcount_set(&newsighand->count, 1);
1312                 memcpy(newsighand->action, oldsighand->action,
1313                        sizeof(newsighand->action));
1314
1315                 write_lock_irq(&tasklist_lock);
1316                 spin_lock(&oldsighand->siglock);
1317                 rcu_assign_pointer(me->sighand, newsighand);
1318                 spin_unlock(&oldsighand->siglock);
1319                 write_unlock_irq(&tasklist_lock);
1320
1321                 __cleanup_sighand(oldsighand);
1322         }
1323         return 0;
1324 }
1325
1326 char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1327 {
1328         task_lock(tsk);
1329         strncpy(buf, tsk->comm, buf_size);
1330         task_unlock(tsk);
1331         return buf;
1332 }
1333 EXPORT_SYMBOL_GPL(__get_task_comm);
1334
1335 /*
1336  * These functions flushes out all traces of the currently running executable
1337  * so that a new one can be started
1338  */
1339
1340 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1341 {
1342         task_lock(tsk);
1343         trace_task_rename(tsk, buf);
1344         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1345         task_unlock(tsk);
1346         perf_event_comm(tsk, exec);
1347 }
1348
1349 /*
1350  * Calling this is the point of no return. None of the failures will be
1351  * seen by userspace since either the process is already taking a fatal
1352  * signal (via de_thread() or coredump), or will have SEGV raised
1353  * (after exec_mmap()) by search_binary_handler (see below).
1354  */
1355 int begin_new_exec(struct linux_binprm * bprm)
1356 {
1357         struct task_struct *me = current;
1358         int retval;
1359
1360         /* Once we are committed compute the creds */
1361         retval = bprm_creds_from_file(bprm);
1362         if (retval)
1363                 return retval;
1364
1365         /*
1366          * Ensure all future errors are fatal.
1367          */
1368         bprm->point_of_no_return = true;
1369
1370         /*
1371          * Make this the only thread in the thread group.
1372          */
1373         retval = de_thread(me);
1374         if (retval)
1375                 goto out;
1376
1377         /*
1378          * Must be called _before_ exec_mmap() as bprm->mm is
1379          * not visibile until then. This also enables the update
1380          * to be lockless.
1381          */
1382         set_mm_exe_file(bprm->mm, bprm->file);
1383
1384         /* If the binary is not readable then enforce mm->dumpable=0 */
1385         would_dump(bprm, bprm->file);
1386         if (bprm->have_execfd)
1387                 would_dump(bprm, bprm->executable);
1388
1389         /*
1390          * Release all of the old mmap stuff
1391          */
1392         acct_arg_size(bprm, 0);
1393         retval = exec_mmap(bprm->mm);
1394         if (retval)
1395                 goto out;
1396
1397         bprm->mm = NULL;
1398
1399 #ifdef CONFIG_POSIX_TIMERS
1400         exit_itimers(me->signal);
1401         flush_itimer_signals();
1402 #endif
1403
1404         /*
1405          * Make the signal table private.
1406          */
1407         retval = unshare_sighand(me);
1408         if (retval)
1409                 goto out_unlock;
1410
1411         /*
1412          * Ensure that the uaccess routines can actually operate on userspace
1413          * pointers:
1414          */
1415         force_uaccess_begin();
1416
1417         me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1418                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1419         flush_thread();
1420         me->personality &= ~bprm->per_clear;
1421
1422         /*
1423          * We have to apply CLOEXEC before we change whether the process is
1424          * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1425          * trying to access the should-be-closed file descriptors of a process
1426          * undergoing exec(2).
1427          */
1428         do_close_on_exec(me->files);
1429
1430         if (bprm->secureexec) {
1431                 /* Make sure parent cannot signal privileged process. */
1432                 me->pdeath_signal = 0;
1433
1434                 /*
1435                  * For secureexec, reset the stack limit to sane default to
1436                  * avoid bad behavior from the prior rlimits. This has to
1437                  * happen before arch_pick_mmap_layout(), which examines
1438                  * RLIMIT_STACK, but after the point of no return to avoid
1439                  * needing to clean up the change on failure.
1440                  */
1441                 if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1442                         bprm->rlim_stack.rlim_cur = _STK_LIM;
1443         }
1444
1445         me->sas_ss_sp = me->sas_ss_size = 0;
1446
1447         /*
1448          * Figure out dumpability. Note that this checking only of current
1449          * is wrong, but userspace depends on it. This should be testing
1450          * bprm->secureexec instead.
1451          */
1452         if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1453             !(uid_eq(current_euid(), current_uid()) &&
1454               gid_eq(current_egid(), current_gid())))
1455                 set_dumpable(current->mm, suid_dumpable);
1456         else
1457                 set_dumpable(current->mm, SUID_DUMP_USER);
1458
1459         perf_event_exec();
1460         __set_task_comm(me, kbasename(bprm->filename), true);
1461
1462         /* An exec changes our domain. We are no longer part of the thread
1463            group */
1464         WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1465         flush_signal_handlers(me, 0);
1466
1467         /*
1468          * install the new credentials for this executable
1469          */
1470         security_bprm_committing_creds(bprm);
1471
1472         commit_creds(bprm->cred);
1473         bprm->cred = NULL;
1474
1475         /*
1476          * Disable monitoring for regular users
1477          * when executing setuid binaries. Must
1478          * wait until new credentials are committed
1479          * by commit_creds() above
1480          */
1481         if (get_dumpable(me->mm) != SUID_DUMP_USER)
1482                 perf_event_exit_task(me);
1483         /*
1484          * cred_guard_mutex must be held at least to this point to prevent
1485          * ptrace_attach() from altering our determination of the task's
1486          * credentials; any time after this it may be unlocked.
1487          */
1488         security_bprm_committed_creds(bprm);
1489
1490         /* Pass the opened binary to the interpreter. */
1491         if (bprm->have_execfd) {
1492                 retval = get_unused_fd_flags(0);
1493                 if (retval < 0)
1494                         goto out_unlock;
1495                 fd_install(retval, bprm->executable);
1496                 bprm->executable = NULL;
1497                 bprm->execfd = retval;
1498         }
1499         return 0;
1500
1501 out_unlock:
1502         mutex_unlock(&me->signal->exec_update_mutex);
1503 out:
1504         return retval;
1505 }
1506 EXPORT_SYMBOL(begin_new_exec);
1507
1508 void would_dump(struct linux_binprm *bprm, struct file *file)
1509 {
1510         struct inode *inode = file_inode(file);
1511         if (inode_permission(inode, MAY_READ) < 0) {
1512                 struct user_namespace *old, *user_ns;
1513                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1514
1515                 /* Ensure mm->user_ns contains the executable */
1516                 user_ns = old = bprm->mm->user_ns;
1517                 while ((user_ns != &init_user_ns) &&
1518                        !privileged_wrt_inode_uidgid(user_ns, inode))
1519                         user_ns = user_ns->parent;
1520
1521                 if (old != user_ns) {
1522                         bprm->mm->user_ns = get_user_ns(user_ns);
1523                         put_user_ns(old);
1524                 }
1525         }
1526 }
1527 EXPORT_SYMBOL(would_dump);
1528
1529 void setup_new_exec(struct linux_binprm * bprm)
1530 {
1531         /* Setup things that can depend upon the personality */
1532         struct task_struct *me = current;
1533
1534         arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1535
1536         arch_setup_new_exec();
1537
1538         /* Set the new mm task size. We have to do that late because it may
1539          * depend on TIF_32BIT which is only updated in flush_thread() on
1540          * some architectures like powerpc
1541          */
1542         me->mm->task_size = TASK_SIZE;
1543         mutex_unlock(&me->signal->exec_update_mutex);
1544         mutex_unlock(&me->signal->cred_guard_mutex);
1545 }
1546 EXPORT_SYMBOL(setup_new_exec);
1547
1548 /* Runs immediately before start_thread() takes over. */
1549 void finalize_exec(struct linux_binprm *bprm)
1550 {
1551         /* Store any stack rlimit changes before starting thread. */
1552         task_lock(current->group_leader);
1553         current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1554         task_unlock(current->group_leader);
1555 }
1556 EXPORT_SYMBOL(finalize_exec);
1557
1558 /*
1559  * Prepare credentials and lock ->cred_guard_mutex.
1560  * setup_new_exec() commits the new creds and drops the lock.
1561  * Or, if exec fails before, free_bprm() should release ->cred and
1562  * and unlock.
1563  */
1564 static int prepare_bprm_creds(struct linux_binprm *bprm)
1565 {
1566         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1567                 return -ERESTARTNOINTR;
1568
1569         bprm->cred = prepare_exec_creds();
1570         if (likely(bprm->cred))
1571                 return 0;
1572
1573         mutex_unlock(&current->signal->cred_guard_mutex);
1574         return -ENOMEM;
1575 }
1576
1577 static void free_bprm(struct linux_binprm *bprm)
1578 {
1579         if (bprm->mm) {
1580                 acct_arg_size(bprm, 0);
1581                 mmput(bprm->mm);
1582         }
1583         free_arg_pages(bprm);
1584         if (bprm->cred) {
1585                 mutex_unlock(&current->signal->cred_guard_mutex);
1586                 abort_creds(bprm->cred);
1587         }
1588         if (bprm->file) {
1589                 allow_write_access(bprm->file);
1590                 fput(bprm->file);
1591         }
1592         if (bprm->executable)
1593                 fput(bprm->executable);
1594         /* If a binfmt changed the interp, free it. */
1595         if (bprm->interp != bprm->filename)
1596                 kfree(bprm->interp);
1597         kfree(bprm->fdpath);
1598         kfree(bprm);
1599 }
1600
1601 static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1602 {
1603         struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1604         int retval = -ENOMEM;
1605         if (!bprm)
1606                 goto out;
1607
1608         if (fd == AT_FDCWD || filename->name[0] == '/') {
1609                 bprm->filename = filename->name;
1610         } else {
1611                 if (filename->name[0] == '\0')
1612                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1613                 else
1614                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1615                                                   fd, filename->name);
1616                 if (!bprm->fdpath)
1617                         goto out_free;
1618
1619                 bprm->filename = bprm->fdpath;
1620         }
1621         bprm->interp = bprm->filename;
1622
1623         retval = bprm_mm_init(bprm);
1624         if (retval)
1625                 goto out_free;
1626         return bprm;
1627
1628 out_free:
1629         free_bprm(bprm);
1630 out:
1631         return ERR_PTR(retval);
1632 }
1633
1634 int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1635 {
1636         /* If a binfmt changed the interp, free it first. */
1637         if (bprm->interp != bprm->filename)
1638                 kfree(bprm->interp);
1639         bprm->interp = kstrdup(interp, GFP_KERNEL);
1640         if (!bprm->interp)
1641                 return -ENOMEM;
1642         return 0;
1643 }
1644 EXPORT_SYMBOL(bprm_change_interp);
1645
1646 /*
1647  * determine how safe it is to execute the proposed program
1648  * - the caller must hold ->cred_guard_mutex to protect against
1649  *   PTRACE_ATTACH or seccomp thread-sync
1650  */
1651 static void check_unsafe_exec(struct linux_binprm *bprm)
1652 {
1653         struct task_struct *p = current, *t;
1654         unsigned n_fs;
1655
1656         if (p->ptrace)
1657                 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1658
1659         /*
1660          * This isn't strictly necessary, but it makes it harder for LSMs to
1661          * mess up.
1662          */
1663         if (task_no_new_privs(current))
1664                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1665
1666         t = p;
1667         n_fs = 1;
1668         spin_lock(&p->fs->lock);
1669         rcu_read_lock();
1670         while_each_thread(p, t) {
1671                 if (t->fs == p->fs)
1672                         n_fs++;
1673         }
1674         rcu_read_unlock();
1675
1676         if (p->fs->users > n_fs)
1677                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1678         else
1679                 p->fs->in_exec = 1;
1680         spin_unlock(&p->fs->lock);
1681 }
1682
1683 static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1684 {
1685         /* Handle suid and sgid on files */
1686         struct inode *inode;
1687         unsigned int mode;
1688         kuid_t uid;
1689         kgid_t gid;
1690
1691         if (!mnt_may_suid(file->f_path.mnt))
1692                 return;
1693
1694         if (task_no_new_privs(current))
1695                 return;
1696
1697         inode = file->f_path.dentry->d_inode;
1698         mode = READ_ONCE(inode->i_mode);
1699         if (!(mode & (S_ISUID|S_ISGID)))
1700                 return;
1701
1702         /* Be careful if suid/sgid is set */
1703         inode_lock(inode);
1704
1705         /* reload atomically mode/uid/gid now that lock held */
1706         mode = inode->i_mode;
1707         uid = inode->i_uid;
1708         gid = inode->i_gid;
1709         inode_unlock(inode);
1710
1711         /* We ignore suid/sgid if there are no mappings for them in the ns */
1712         if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1713                  !kgid_has_mapping(bprm->cred->user_ns, gid))
1714                 return;
1715
1716         if (mode & S_ISUID) {
1717                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1718                 bprm->cred->euid = uid;
1719         }
1720
1721         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1722                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1723                 bprm->cred->egid = gid;
1724         }
1725 }
1726
1727 /*
1728  * Compute brpm->cred based upon the final binary.
1729  */
1730 static int bprm_creds_from_file(struct linux_binprm *bprm)
1731 {
1732         /* Compute creds based on which file? */
1733         struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1734
1735         bprm_fill_uid(bprm, file);
1736         return security_bprm_creds_from_file(bprm, file);
1737 }
1738
1739 /*
1740  * Fill the binprm structure from the inode.
1741  * Read the first BINPRM_BUF_SIZE bytes
1742  *
1743  * This may be called multiple times for binary chains (scripts for example).
1744  */
1745 static int prepare_binprm(struct linux_binprm *bprm)
1746 {
1747         loff_t pos = 0;
1748
1749         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1750         return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1751 }
1752
1753 /*
1754  * Arguments are '\0' separated strings found at the location bprm->p
1755  * points to; chop off the first by relocating brpm->p to right after
1756  * the first '\0' encountered.
1757  */
1758 int remove_arg_zero(struct linux_binprm *bprm)
1759 {
1760         int ret = 0;
1761         unsigned long offset;
1762         char *kaddr;
1763         struct page *page;
1764
1765         if (!bprm->argc)
1766                 return 0;
1767
1768         do {
1769                 offset = bprm->p & ~PAGE_MASK;
1770                 page = get_arg_page(bprm, bprm->p, 0);
1771                 if (!page) {
1772                         ret = -EFAULT;
1773                         goto out;
1774                 }
1775                 kaddr = kmap_atomic(page);
1776
1777                 for (; offset < PAGE_SIZE && kaddr[offset];
1778                                 offset++, bprm->p++)
1779                         ;
1780
1781                 kunmap_atomic(kaddr);
1782                 put_arg_page(page);
1783         } while (offset == PAGE_SIZE);
1784
1785         bprm->p++;
1786         bprm->argc--;
1787         ret = 0;
1788
1789 out:
1790         return ret;
1791 }
1792 EXPORT_SYMBOL(remove_arg_zero);
1793
1794 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1795 /*
1796  * cycle the list of binary formats handler, until one recognizes the image
1797  */
1798 static int search_binary_handler(struct linux_binprm *bprm)
1799 {
1800         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1801         struct linux_binfmt *fmt;
1802         int retval;
1803
1804         retval = prepare_binprm(bprm);
1805         if (retval < 0)
1806                 return retval;
1807
1808         retval = security_bprm_check(bprm);
1809         if (retval)
1810                 return retval;
1811
1812         retval = -ENOENT;
1813  retry:
1814         read_lock(&binfmt_lock);
1815         list_for_each_entry(fmt, &formats, lh) {
1816                 if (!try_module_get(fmt->module))
1817                         continue;
1818                 read_unlock(&binfmt_lock);
1819
1820                 retval = fmt->load_binary(bprm);
1821
1822                 read_lock(&binfmt_lock);
1823                 put_binfmt(fmt);
1824                 if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1825                         read_unlock(&binfmt_lock);
1826                         return retval;
1827                 }
1828         }
1829         read_unlock(&binfmt_lock);
1830
1831         if (need_retry) {
1832                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1833                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1834                         return retval;
1835                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1836                         return retval;
1837                 need_retry = false;
1838                 goto retry;
1839         }
1840
1841         return retval;
1842 }
1843
1844 static int exec_binprm(struct linux_binprm *bprm)
1845 {
1846         pid_t old_pid, old_vpid;
1847         int ret, depth;
1848
1849         /* Need to fetch pid before load_binary changes it */
1850         old_pid = current->pid;
1851         rcu_read_lock();
1852         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1853         rcu_read_unlock();
1854
1855         /* This allows 4 levels of binfmt rewrites before failing hard. */
1856         for (depth = 0;; depth++) {
1857                 struct file *exec;
1858                 if (depth > 5)
1859                         return -ELOOP;
1860
1861                 ret = search_binary_handler(bprm);
1862                 if (ret < 0)
1863                         return ret;
1864                 if (!bprm->interpreter)
1865                         break;
1866
1867                 exec = bprm->file;
1868                 bprm->file = bprm->interpreter;
1869                 bprm->interpreter = NULL;
1870
1871                 allow_write_access(exec);
1872                 if (unlikely(bprm->have_execfd)) {
1873                         if (bprm->executable) {
1874                                 fput(exec);
1875                                 return -ENOEXEC;
1876                         }
1877                         bprm->executable = exec;
1878                 } else
1879                         fput(exec);
1880         }
1881
1882         audit_bprm(bprm);
1883         trace_sched_process_exec(current, old_pid, bprm);
1884         ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1885         proc_exec_connector(current);
1886         return 0;
1887 }
1888
1889 /*
1890  * sys_execve() executes a new program.
1891  */
1892 static int bprm_execve(struct linux_binprm *bprm,
1893                        int fd, struct filename *filename, int flags)
1894 {
1895         struct file *file;
1896         struct files_struct *displaced;
1897         int retval;
1898
1899         /*
1900          * Cancel any io_uring activity across execve
1901          */
1902         io_uring_task_cancel();
1903
1904         retval = unshare_files(&displaced);
1905         if (retval)
1906                 return retval;
1907
1908         retval = prepare_bprm_creds(bprm);
1909         if (retval)
1910                 goto out_files;
1911
1912         check_unsafe_exec(bprm);
1913         current->in_execve = 1;
1914
1915         file = do_open_execat(fd, filename, flags);
1916         retval = PTR_ERR(file);
1917         if (IS_ERR(file))
1918                 goto out_unmark;
1919
1920         sched_exec();
1921
1922         bprm->file = file;
1923         /*
1924          * Record that a name derived from an O_CLOEXEC fd will be
1925          * inaccessible after exec. Relies on having exclusive access to
1926          * current->files (due to unshare_files above).
1927          */
1928         if (bprm->fdpath &&
1929             close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1930                 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1931
1932         /* Set the unchanging part of bprm->cred */
1933         retval = security_bprm_creds_for_exec(bprm);
1934         if (retval)
1935                 goto out;
1936
1937         retval = exec_binprm(bprm);
1938         if (retval < 0)
1939                 goto out;
1940
1941         /* execve succeeded */
1942         current->fs->in_exec = 0;
1943         current->in_execve = 0;
1944         rseq_execve(current);
1945         acct_update_integrals(current);
1946         task_numa_free(current, false);
1947         if (displaced)
1948                 put_files_struct(displaced);
1949         return retval;
1950
1951 out:
1952         /*
1953          * If past the point of no return ensure the the code never
1954          * returns to the userspace process.  Use an existing fatal
1955          * signal if present otherwise terminate the process with
1956          * SIGSEGV.
1957          */
1958         if (bprm->point_of_no_return && !fatal_signal_pending(current))
1959                 force_sigsegv(SIGSEGV);
1960
1961 out_unmark:
1962         current->fs->in_exec = 0;
1963         current->in_execve = 0;
1964
1965 out_files:
1966         if (displaced)
1967                 reset_files_struct(displaced);
1968
1969         return retval;
1970 }
1971
1972 static int do_execveat_common(int fd, struct filename *filename,
1973                               struct user_arg_ptr argv,
1974                               struct user_arg_ptr envp,
1975                               int flags)
1976 {
1977         struct linux_binprm *bprm;
1978         int retval;
1979
1980         if (IS_ERR(filename))
1981                 return PTR_ERR(filename);
1982
1983         /*
1984          * We move the actual failure in case of RLIMIT_NPROC excess from
1985          * set*uid() to execve() because too many poorly written programs
1986          * don't check setuid() return code.  Here we additionally recheck
1987          * whether NPROC limit is still exceeded.
1988          */
1989         if ((current->flags & PF_NPROC_EXCEEDED) &&
1990             atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1991                 retval = -EAGAIN;
1992                 goto out_ret;
1993         }
1994
1995         /* We're below the limit (still or again), so we don't want to make
1996          * further execve() calls fail. */
1997         current->flags &= ~PF_NPROC_EXCEEDED;
1998
1999         bprm = alloc_bprm(fd, filename);
2000         if (IS_ERR(bprm)) {
2001                 retval = PTR_ERR(bprm);
2002                 goto out_ret;
2003         }
2004
2005         retval = count(argv, MAX_ARG_STRINGS);
2006         if (retval < 0)
2007                 goto out_free;
2008         bprm->argc = retval;
2009
2010         retval = count(envp, MAX_ARG_STRINGS);
2011         if (retval < 0)
2012                 goto out_free;
2013         bprm->envc = retval;
2014
2015         retval = bprm_stack_limits(bprm);
2016         if (retval < 0)
2017                 goto out_free;
2018
2019         retval = copy_string_kernel(bprm->filename, bprm);
2020         if (retval < 0)
2021                 goto out_free;
2022         bprm->exec = bprm->p;
2023
2024         retval = copy_strings(bprm->envc, envp, bprm);
2025         if (retval < 0)
2026                 goto out_free;
2027
2028         retval = copy_strings(bprm->argc, argv, bprm);
2029         if (retval < 0)
2030                 goto out_free;
2031
2032         retval = bprm_execve(bprm, fd, filename, flags);
2033 out_free:
2034         free_bprm(bprm);
2035
2036 out_ret:
2037         putname(filename);
2038         return retval;
2039 }
2040
2041 int kernel_execve(const char *kernel_filename,
2042                   const char *const *argv, const char *const *envp)
2043 {
2044         struct filename *filename;
2045         struct linux_binprm *bprm;
2046         int fd = AT_FDCWD;
2047         int retval;
2048
2049         filename = getname_kernel(kernel_filename);
2050         if (IS_ERR(filename))
2051                 return PTR_ERR(filename);
2052
2053         bprm = alloc_bprm(fd, filename);
2054         if (IS_ERR(bprm)) {
2055                 retval = PTR_ERR(bprm);
2056                 goto out_ret;
2057         }
2058
2059         retval = count_strings_kernel(argv);
2060         if (retval < 0)
2061                 goto out_free;
2062         bprm->argc = retval;
2063
2064         retval = count_strings_kernel(envp);
2065         if (retval < 0)
2066                 goto out_free;
2067         bprm->envc = retval;
2068
2069         retval = bprm_stack_limits(bprm);
2070         if (retval < 0)
2071                 goto out_free;
2072
2073         retval = copy_string_kernel(bprm->filename, bprm);
2074         if (retval < 0)
2075                 goto out_free;
2076         bprm->exec = bprm->p;
2077
2078         retval = copy_strings_kernel(bprm->envc, envp, bprm);
2079         if (retval < 0)
2080                 goto out_free;
2081
2082         retval = copy_strings_kernel(bprm->argc, argv, bprm);
2083         if (retval < 0)
2084                 goto out_free;
2085
2086         retval = bprm_execve(bprm, fd, filename, 0);
2087 out_free:
2088         free_bprm(bprm);
2089 out_ret:
2090         putname(filename);
2091         return retval;
2092 }
2093
2094 static int do_execve(struct filename *filename,
2095         const char __user *const __user *__argv,
2096         const char __user *const __user *__envp)
2097 {
2098         struct user_arg_ptr argv = { .ptr.native = __argv };
2099         struct user_arg_ptr envp = { .ptr.native = __envp };
2100         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2101 }
2102
2103 static int do_execveat(int fd, struct filename *filename,
2104                 const char __user *const __user *__argv,
2105                 const char __user *const __user *__envp,
2106                 int flags)
2107 {
2108         struct user_arg_ptr argv = { .ptr.native = __argv };
2109         struct user_arg_ptr envp = { .ptr.native = __envp };
2110
2111         return do_execveat_common(fd, filename, argv, envp, flags);
2112 }
2113
2114 #ifdef CONFIG_COMPAT
2115 static int compat_do_execve(struct filename *filename,
2116         const compat_uptr_t __user *__argv,
2117         const compat_uptr_t __user *__envp)
2118 {
2119         struct user_arg_ptr argv = {
2120                 .is_compat = true,
2121                 .ptr.compat = __argv,
2122         };
2123         struct user_arg_ptr envp = {
2124                 .is_compat = true,
2125                 .ptr.compat = __envp,
2126         };
2127         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2128 }
2129
2130 static int compat_do_execveat(int fd, struct filename *filename,
2131                               const compat_uptr_t __user *__argv,
2132                               const compat_uptr_t __user *__envp,
2133                               int flags)
2134 {
2135         struct user_arg_ptr argv = {
2136                 .is_compat = true,
2137                 .ptr.compat = __argv,
2138         };
2139         struct user_arg_ptr envp = {
2140                 .is_compat = true,
2141                 .ptr.compat = __envp,
2142         };
2143         return do_execveat_common(fd, filename, argv, envp, flags);
2144 }
2145 #endif
2146
2147 void set_binfmt(struct linux_binfmt *new)
2148 {
2149         struct mm_struct *mm = current->mm;
2150
2151         if (mm->binfmt)
2152                 module_put(mm->binfmt->module);
2153
2154         mm->binfmt = new;
2155         if (new)
2156                 __module_get(new->module);
2157 }
2158 EXPORT_SYMBOL(set_binfmt);
2159
2160 /*
2161  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2162  */
2163 void set_dumpable(struct mm_struct *mm, int value)
2164 {
2165         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2166                 return;
2167
2168         set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2169 }
2170
2171 SYSCALL_DEFINE3(execve,
2172                 const char __user *, filename,
2173                 const char __user *const __user *, argv,
2174                 const char __user *const __user *, envp)
2175 {
2176         return do_execve(getname(filename), argv, envp);
2177 }
2178
2179 SYSCALL_DEFINE5(execveat,
2180                 int, fd, const char __user *, filename,
2181                 const char __user *const __user *, argv,
2182                 const char __user *const __user *, envp,
2183                 int, flags)
2184 {
2185         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
2186
2187         return do_execveat(fd,
2188                            getname_flags(filename, lookup_flags, NULL),
2189                            argv, envp, flags);
2190 }
2191
2192 #ifdef CONFIG_COMPAT
2193 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2194         const compat_uptr_t __user *, argv,
2195         const compat_uptr_t __user *, envp)
2196 {
2197         return compat_do_execve(getname(filename), argv, envp);
2198 }
2199
2200 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2201                        const char __user *, filename,
2202                        const compat_uptr_t __user *, argv,
2203                        const compat_uptr_t __user *, envp,
2204                        int,  flags)
2205 {
2206         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
2207
2208         return compat_do_execveat(fd,
2209                                   getname_flags(filename, lookup_flags, NULL),
2210                                   argv, envp, flags);
2211 }
2212 #endif