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/kernel_read_file.h>
  27 #include <linux/slab.h>
  28 #include <linux/file.h>
  29 #include <linux/fdtable.h>
  30 #include <linux/mm.h>
  31 #include <linux/vmacache.h>
  32 #include <linux/stat.h>
  33 #include <linux/fcntl.h>
  34 #include <linux/swap.h>
  35 #include <linux/string.h>
  36 #include <linux/init.h>
  37 #include <linux/sched/mm.h>
  38 #include <linux/sched/coredump.h>
  39 #include <linux/sched/signal.h>
  40 #include <linux/sched/numa_balancing.h>
  41 #include <linux/sched/task.h>
  42 #include <linux/pagemap.h>
  43 #include <linux/perf_event.h>
  44 #include <linux/highmem.h>
  45 #include <linux/spinlock.h>
  46 #include <linux/key.h>
  47 #include <linux/personality.h>
  48 #include <linux/binfmts.h>
  49 #include <linux/utsname.h>
  50 #include <linux/pid_namespace.h>
  51 #include <linux/module.h>
  52 #include <linux/namei.h>
  53 #include <linux/mount.h>
  54 #include <linux/security.h>
  55 #include <linux/syscalls.h>
  56 #include <linux/tsacct_kern.h>
  57 #include <linux/cn_proc.h>
  58 #include <linux/audit.h>
  59 #include <linux/tracehook.h>
  60 #include <linux/kmod.h>
  61 #include <linux/fsnotify.h>
  62 #include <linux/fs_struct.h>
  63 #include <linux/oom.h>
  64 #include <linux/compat.h>
  65 #include <linux/vmalloc.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         void *allocated = NULL;
 959         int ret;
 960
 961         if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
 962                 return -EINVAL;
 963
 964         ret = deny_write_access(file);
 965         if (ret)
 966                 return ret;
 967
 968         ret = security_kernel_read_file(file, id);
 969         if (ret)
 970                 goto out;
 971
 972         i_size = i_size_read(file_inode(file));
 973         if (i_size <= 0) {
 974                 ret = -EINVAL;
 975                 goto out;
 976         }
 977         if (i_size > SIZE_MAX || (max_size > 0 && i_size > max_size)) {
 978                 ret = -EFBIG;
 979                 goto out;
 980         }
 981
 982         if (!*buf)
 983                 *buf = allocated = vmalloc(i_size);
 984         if (!*buf) {
 985                 ret = -ENOMEM;
 986                 goto out;
 987         }
 988
 989         pos = 0;
 990         while (pos < i_size) {
 991                 bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
 992                 if (bytes < 0) {
 993                         ret = bytes;
 994                         goto out_free;
 995                 }
 996
 997                 if (bytes == 0)
 998                         break;
 999         }
1000
1001         if (pos != i_size) {
1002                 ret = -EIO;
1003                 goto out_free;
1004         }
1005
1006         ret = security_kernel_post_read_file(file, *buf, i_size, id);
1007         if (!ret)
1008                 *size = pos;
1009
1010 out_free:
1011         if (ret < 0) {
1012                 if (allocated) {
1013                         vfree(*buf);
1014                         *buf = NULL;
1015                 }
1016         }
1017
1018 out:
1019         allow_write_access(file);
1020         return ret;
1021 }
1022 EXPORT_SYMBOL_GPL(kernel_read_file);
1023
1024 int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
1025                                loff_t max_size, enum kernel_read_file_id id)
1026 {
1027         struct file *file;
1028         int ret;
1029
1030         if (!path || !*path)
1031                 return -EINVAL;
1032
1033         file = filp_open(path, O_RDONLY, 0);
1034         if (IS_ERR(file))
1035                 return PTR_ERR(file);
1036
1037         ret = kernel_read_file(file, buf, size, max_size, id);
1038         fput(file);
1039         return ret;
1040 }
1041 EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
1042
1043 int kernel_read_file_from_path_initns(const char *path, void **buf,
1044                                       loff_t *size, loff_t max_size,
1045                                       enum kernel_read_file_id id)
1046 {
1047         struct file *file;
1048         struct path root;
1049         int ret;
1050
1051         if (!path || !*path)
1052                 return -EINVAL;
1053
1054         task_lock(&init_task);
1055         get_fs_root(init_task.fs, &root);
1056         task_unlock(&init_task);
1057
1058         file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
1059         path_put(&root);
1060         if (IS_ERR(file))
1061                 return PTR_ERR(file);
1062
1063         ret = kernel_read_file(file, buf, size, max_size, id);
1064         fput(file);
1065         return ret;
1066 }
1067 EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
1068
1069 int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
1070                              enum kernel_read_file_id id)
1071 {
1072         struct fd f = fdget(fd);
1073         int ret = -EBADF;
1074
1075         if (!f.file)
1076                 goto out;
1077
1078         ret = kernel_read_file(f.file, buf, size, max_size, id);
1079 out:
1080         fdput(f);
1081         return ret;
1082 }
1083 EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
1084
1085 #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
1086     defined(CONFIG_BINFMT_ELF_FDPIC)
1087 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
1088 {
1089         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
1090         if (res > 0)
1091                 flush_icache_user_range(addr, addr + len);
1092         return res;
1093 }
1094 EXPORT_SYMBOL(read_code);
1095 #endif
1096
1097 /*
1098  * Maps the mm_struct mm into the current task struct.
1099  * On success, this function returns with the mutex
1100  * exec_update_mutex locked.
1101  */
1102 static int exec_mmap(struct mm_struct *mm)
1103 {
1104         struct task_struct *tsk;
1105         struct mm_struct *old_mm, *active_mm;
1106         int ret;
1107
1108         /* Notify parent that we're no longer interested in the old VM */
1109         tsk = current;
1110         old_mm = current->mm;
1111         exec_mm_release(tsk, old_mm);
1112         if (old_mm)
1113                 sync_mm_rss(old_mm);
1114
1115         ret = mutex_lock_killable(&tsk->signal->exec_update_mutex);
1116         if (ret)
1117                 return ret;
1118
1119         if (old_mm) {
1120                 /*
1121                  * Make sure that if there is a core dump in progress
1122                  * for the old mm, we get out and die instead of going
1123                  * through with the exec.  We must hold mmap_lock around
1124                  * checking core_state and changing tsk->mm.
1125                  */
1126                 mmap_read_lock(old_mm);
1127                 if (unlikely(old_mm->core_state)) {
1128                         mmap_read_unlock(old_mm);
1129                         mutex_unlock(&tsk->signal->exec_update_mutex);
1130                         return -EINTR;
1131                 }
1132         }
1133
1134         task_lock(tsk);
1135         active_mm = tsk->active_mm;
1136         membarrier_exec_mmap(mm);
1137         tsk->mm = mm;
1138         tsk->active_mm = mm;
1139         activate_mm(active_mm, mm);
1140         tsk->mm->vmacache_seqnum = 0;
1141         vmacache_flush(tsk);
1142         task_unlock(tsk);
1143         if (old_mm) {
1144                 mmap_read_unlock(old_mm);
1145                 BUG_ON(active_mm != old_mm);
1146                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1147                 mm_update_next_owner(old_mm);
1148                 mmput(old_mm);
1149                 return 0;
1150         }
1151         mmdrop(active_mm);
1152         return 0;
1153 }
1154
1155 static int de_thread(struct task_struct *tsk)
1156 {
1157         struct signal_struct *sig = tsk->signal;
1158         struct sighand_struct *oldsighand = tsk->sighand;
1159         spinlock_t *lock = &oldsighand->siglock;
1160
1161         if (thread_group_empty(tsk))
1162                 goto no_thread_group;
1163
1164         /*
1165          * Kill all other threads in the thread group.
1166          */
1167         spin_lock_irq(lock);
1168         if (signal_group_exit(sig)) {
1169                 /*
1170                  * Another group action in progress, just
1171                  * return so that the signal is processed.
1172                  */
1173                 spin_unlock_irq(lock);
1174                 return -EAGAIN;
1175         }
1176
1177         sig->group_exit_task = tsk;
1178         sig->notify_count = zap_other_threads(tsk);
1179         if (!thread_group_leader(tsk))
1180                 sig->notify_count--;
1181
1182         while (sig->notify_count) {
1183                 __set_current_state(TASK_KILLABLE);
1184                 spin_unlock_irq(lock);
1185                 schedule();
1186                 if (__fatal_signal_pending(tsk))
1187                         goto killed;
1188                 spin_lock_irq(lock);
1189         }
1190         spin_unlock_irq(lock);
1191
1192         /*
1193          * At this point all other threads have exited, all we have to
1194          * do is to wait for the thread group leader to become inactive,
1195          * and to assume its PID:
1196          */
1197         if (!thread_group_leader(tsk)) {
1198                 struct task_struct *leader = tsk->group_leader;
1199
1200                 for (;;) {
1201                         cgroup_threadgroup_change_begin(tsk);
1202                         write_lock_irq(&tasklist_lock);
1203                         /*
1204                          * Do this under tasklist_lock to ensure that
1205                          * exit_notify() can't miss ->group_exit_task
1206                          */
1207                         sig->notify_count = -1;
1208                         if (likely(leader->exit_state))
1209                                 break;
1210                         __set_current_state(TASK_KILLABLE);
1211                         write_unlock_irq(&tasklist_lock);
1212                         cgroup_threadgroup_change_end(tsk);
1213                         schedule();
1214                         if (__fatal_signal_pending(tsk))
1215                                 goto killed;
1216                 }
1217
1218                 /*
1219                  * The only record we have of the real-time age of a
1220                  * process, regardless of execs it's done, is start_time.
1221                  * All the past CPU time is accumulated in signal_struct
1222                  * from sister threads now dead.  But in this non-leader
1223                  * exec, nothing survives from the original leader thread,
1224                  * whose birth marks the true age of this process now.
1225                  * When we take on its identity by switching to its PID, we
1226                  * also take its birthdate (always earlier than our own).
1227                  */
1228                 tsk->start_time = leader->start_time;
1229                 tsk->start_boottime = leader->start_boottime;
1230
1231                 BUG_ON(!same_thread_group(leader, tsk));
1232                 /*
1233                  * An exec() starts a new thread group with the
1234                  * TGID of the previous thread group. Rehash the
1235                  * two threads with a switched PID, and release
1236                  * the former thread group leader:
1237                  */
1238
1239                 /* Become a process group leader with the old leader's pid.
1240                  * The old leader becomes a thread of the this thread group.
1241                  */
1242                 exchange_tids(tsk, leader);
1243                 transfer_pid(leader, tsk, PIDTYPE_TGID);
1244                 transfer_pid(leader, tsk, PIDTYPE_PGID);
1245                 transfer_pid(leader, tsk, PIDTYPE_SID);
1246
1247                 list_replace_rcu(&leader->tasks, &tsk->tasks);
1248                 list_replace_init(&leader->sibling, &tsk->sibling);
1249
1250                 tsk->group_leader = tsk;
1251                 leader->group_leader = tsk;
1252
1253                 tsk->exit_signal = SIGCHLD;
1254                 leader->exit_signal = -1;
1255
1256                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1257                 leader->exit_state = EXIT_DEAD;
1258
1259                 /*
1260                  * We are going to release_task()->ptrace_unlink() silently,
1261                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1262                  * the tracer wont't block again waiting for this thread.
1263                  */
1264                 if (unlikely(leader->ptrace))
1265                         __wake_up_parent(leader, leader->parent);
1266                 write_unlock_irq(&tasklist_lock);
1267                 cgroup_threadgroup_change_end(tsk);
1268
1269                 release_task(leader);
1270         }
1271
1272         sig->group_exit_task = NULL;
1273         sig->notify_count = 0;
1274
1275 no_thread_group:
1276         /* we have changed execution domain */
1277         tsk->exit_signal = SIGCHLD;
1278
1279         BUG_ON(!thread_group_leader(tsk));
1280         return 0;
1281
1282 killed:
1283         /* protects against exit_notify() and __exit_signal() */
1284         read_lock(&tasklist_lock);
1285         sig->group_exit_task = NULL;
1286         sig->notify_count = 0;
1287         read_unlock(&tasklist_lock);
1288         return -EAGAIN;
1289 }
1290
1291
1292 /*
1293  * This function makes sure the current process has its own signal table,
1294  * so that flush_signal_handlers can later reset the handlers without
1295  * disturbing other processes.  (Other processes might share the signal
1296  * table via the CLONE_SIGHAND option to clone().)
1297  */
1298 static int unshare_sighand(struct task_struct *me)
1299 {
1300         struct sighand_struct *oldsighand = me->sighand;
1301
1302         if (refcount_read(&oldsighand->count) != 1) {
1303                 struct sighand_struct *newsighand;
1304                 /*
1305                  * This ->sighand is shared with the CLONE_SIGHAND
1306                  * but not CLONE_THREAD task, switch to the new one.
1307                  */
1308                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1309                 if (!newsighand)
1310                         return -ENOMEM;
1311
1312                 refcount_set(&newsighand->count, 1);
1313                 memcpy(newsighand->action, oldsighand->action,
1314                        sizeof(newsighand->action));
1315
1316                 write_lock_irq(&tasklist_lock);
1317                 spin_lock(&oldsighand->siglock);
1318                 rcu_assign_pointer(me->sighand, newsighand);
1319                 spin_unlock(&oldsighand->siglock);
1320                 write_unlock_irq(&tasklist_lock);
1321
1322                 __cleanup_sighand(oldsighand);
1323         }
1324         return 0;
1325 }
1326
1327 char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1328 {
1329         task_lock(tsk);
1330         strncpy(buf, tsk->comm, buf_size);
1331         task_unlock(tsk);
1332         return buf;
1333 }
1334 EXPORT_SYMBOL_GPL(__get_task_comm);
1335
1336 /*
1337  * These functions flushes out all traces of the currently running executable
1338  * so that a new one can be started
1339  */
1340
1341 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1342 {
1343         task_lock(tsk);
1344         trace_task_rename(tsk, buf);
1345         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1346         task_unlock(tsk);
1347         perf_event_comm(tsk, exec);
1348 }
1349
1350 /*
1351  * Calling this is the point of no return. None of the failures will be
1352  * seen by userspace since either the process is already taking a fatal
1353  * signal (via de_thread() or coredump), or will have SEGV raised
1354  * (after exec_mmap()) by search_binary_handler (see below).
1355  */
1356 int begin_new_exec(struct linux_binprm * bprm)
1357 {
1358         struct task_struct *me = current;
1359         int retval;
1360
1361         /* Once we are committed compute the creds */
1362         retval = bprm_creds_from_file(bprm);
1363         if (retval)
1364                 return retval;
1365
1366         /*
1367          * Ensure all future errors are fatal.
1368          */
1369         bprm->point_of_no_return = true;
1370
1371         /*
1372          * Make this the only thread in the thread group.
1373          */
1374         retval = de_thread(me);
1375         if (retval)
1376                 goto out;
1377
1378         /*
1379          * Must be called _before_ exec_mmap() as bprm->mm is
1380          * not visibile until then. This also enables the update
1381          * to be lockless.
1382          */
1383         set_mm_exe_file(bprm->mm, bprm->file);
1384
1385         /* If the binary is not readable then enforce mm->dumpable=0 */
1386         would_dump(bprm, bprm->file);
1387         if (bprm->have_execfd)
1388                 would_dump(bprm, bprm->executable);
1389
1390         /*
1391          * Release all of the old mmap stuff
1392          */
1393         acct_arg_size(bprm, 0);
1394         retval = exec_mmap(bprm->mm);
1395         if (retval)
1396                 goto out;
1397
1398         bprm->mm = NULL;
1399
1400 #ifdef CONFIG_POSIX_TIMERS
1401         exit_itimers(me->signal);
1402         flush_itimer_signals();
1403 #endif
1404
1405         /*
1406          * Make the signal table private.
1407          */
1408         retval = unshare_sighand(me);
1409         if (retval)
1410                 goto out_unlock;
1411
1412         /*
1413          * Ensure that the uaccess routines can actually operate on userspace
1414          * pointers:
1415          */
1416         force_uaccess_begin();
1417
1418         me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1419                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1420         flush_thread();
1421         me->personality &= ~bprm->per_clear;
1422
1423         /*
1424          * We have to apply CLOEXEC before we change whether the process is
1425          * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1426          * trying to access the should-be-closed file descriptors of a process
1427          * undergoing exec(2).
1428          */
1429         do_close_on_exec(me->files);
1430
1431         if (bprm->secureexec) {
1432                 /* Make sure parent cannot signal privileged process. */
1433                 me->pdeath_signal = 0;
1434
1435                 /*
1436                  * For secureexec, reset the stack limit to sane default to
1437                  * avoid bad behavior from the prior rlimits. This has to
1438                  * happen before arch_pick_mmap_layout(), which examines
1439                  * RLIMIT_STACK, but after the point of no return to avoid
1440                  * needing to clean up the change on failure.
1441                  */
1442                 if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1443                         bprm->rlim_stack.rlim_cur = _STK_LIM;
1444         }
1445
1446         me->sas_ss_sp = me->sas_ss_size = 0;
1447
1448         /*
1449          * Figure out dumpability. Note that this checking only of current
1450          * is wrong, but userspace depends on it. This should be testing
1451          * bprm->secureexec instead.
1452          */
1453         if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1454             !(uid_eq(current_euid(), current_uid()) &&
1455               gid_eq(current_egid(), current_gid())))
1456                 set_dumpable(current->mm, suid_dumpable);
1457         else
1458                 set_dumpable(current->mm, SUID_DUMP_USER);
1459
1460         perf_event_exec();
1461         __set_task_comm(me, kbasename(bprm->filename), true);
1462
1463         /* An exec changes our domain. We are no longer part of the thread
1464            group */
1465         WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1466         flush_signal_handlers(me, 0);
1467
1468         /*
1469          * install the new credentials for this executable
1470          */
1471         security_bprm_committing_creds(bprm);
1472
1473         commit_creds(bprm->cred);
1474         bprm->cred = NULL;
1475
1476         /*
1477          * Disable monitoring for regular users
1478          * when executing setuid binaries. Must
1479          * wait until new credentials are committed
1480          * by commit_creds() above
1481          */
1482         if (get_dumpable(me->mm) != SUID_DUMP_USER)
1483                 perf_event_exit_task(me);
1484         /*
1485          * cred_guard_mutex must be held at least to this point to prevent
1486          * ptrace_attach() from altering our determination of the task's
1487          * credentials; any time after this it may be unlocked.
1488          */
1489         security_bprm_committed_creds(bprm);
1490
1491         /* Pass the opened binary to the interpreter. */
1492         if (bprm->have_execfd) {
1493                 retval = get_unused_fd_flags(0);
1494                 if (retval < 0)
1495                         goto out_unlock;
1496                 fd_install(retval, bprm->executable);
1497                 bprm->executable = NULL;
1498                 bprm->execfd = retval;
1499         }
1500         return 0;
1501
1502 out_unlock:
1503         mutex_unlock(&me->signal->exec_update_mutex);
1504 out:
1505         return retval;
1506 }
1507 EXPORT_SYMBOL(begin_new_exec);
1508
1509 void would_dump(struct linux_binprm *bprm, struct file *file)
1510 {
1511         struct inode *inode = file_inode(file);
1512         if (inode_permission(inode, MAY_READ) < 0) {
1513                 struct user_namespace *old, *user_ns;
1514                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1515
1516                 /* Ensure mm->user_ns contains the executable */
1517                 user_ns = old = bprm->mm->user_ns;
1518                 while ((user_ns != &init_user_ns) &&
1519                        !privileged_wrt_inode_uidgid(user_ns, inode))
1520                         user_ns = user_ns->parent;
1521
1522                 if (old != user_ns) {
1523                         bprm->mm->user_ns = get_user_ns(user_ns);
1524                         put_user_ns(old);
1525                 }
1526         }
1527 }
1528 EXPORT_SYMBOL(would_dump);
1529
1530 void setup_new_exec(struct linux_binprm * bprm)
1531 {
1532         /* Setup things that can depend upon the personality */
1533         struct task_struct *me = current;
1534
1535         arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1536
1537         arch_setup_new_exec();
1538
1539         /* Set the new mm task size. We have to do that late because it may
1540          * depend on TIF_32BIT which is only updated in flush_thread() on
1541          * some architectures like powerpc
1542          */
1543         me->mm->task_size = TASK_SIZE;
1544         mutex_unlock(&me->signal->exec_update_mutex);
1545         mutex_unlock(&me->signal->cred_guard_mutex);
1546 }
1547 EXPORT_SYMBOL(setup_new_exec);
1548
1549 /* Runs immediately before start_thread() takes over. */
1550 void finalize_exec(struct linux_binprm *bprm)
1551 {
1552         /* Store any stack rlimit changes before starting thread. */
1553         task_lock(current->group_leader);
1554         current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1555         task_unlock(current->group_leader);
1556 }
1557 EXPORT_SYMBOL(finalize_exec);
1558
1559 /*
1560  * Prepare credentials and lock ->cred_guard_mutex.
1561  * setup_new_exec() commits the new creds and drops the lock.
1562  * Or, if exec fails before, free_bprm() should release ->cred and
1563  * and unlock.
1564  */
1565 static int prepare_bprm_creds(struct linux_binprm *bprm)
1566 {
1567         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1568                 return -ERESTARTNOINTR;
1569
1570         bprm->cred = prepare_exec_creds();
1571         if (likely(bprm->cred))
1572                 return 0;
1573
1574         mutex_unlock(&current->signal->cred_guard_mutex);
1575         return -ENOMEM;
1576 }
1577
1578 static void free_bprm(struct linux_binprm *bprm)
1579 {
1580         if (bprm->mm) {
1581                 acct_arg_size(bprm, 0);
1582                 mmput(bprm->mm);
1583         }
1584         free_arg_pages(bprm);
1585         if (bprm->cred) {
1586                 mutex_unlock(&current->signal->cred_guard_mutex);
1587                 abort_creds(bprm->cred);
1588         }
1589         if (bprm->file) {
1590                 allow_write_access(bprm->file);
1591                 fput(bprm->file);
1592         }
1593         if (bprm->executable)
1594                 fput(bprm->executable);
1595         /* If a binfmt changed the interp, free it. */
1596         if (bprm->interp != bprm->filename)
1597                 kfree(bprm->interp);
1598         kfree(bprm->fdpath);
1599         kfree(bprm);
1600 }
1601
1602 static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1603 {
1604         struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1605         int retval = -ENOMEM;
1606         if (!bprm)
1607                 goto out;
1608
1609         if (fd == AT_FDCWD || filename->name[0] == '/') {
1610                 bprm->filename = filename->name;
1611         } else {
1612                 if (filename->name[0] == '\0')
1613                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1614                 else
1615                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1616                                                   fd, filename->name);
1617                 if (!bprm->fdpath)
1618                         goto out_free;
1619
1620                 bprm->filename = bprm->fdpath;
1621         }
1622         bprm->interp = bprm->filename;
1623
1624         retval = bprm_mm_init(bprm);
1625         if (retval)
1626                 goto out_free;
1627         return bprm;
1628
1629 out_free:
1630         free_bprm(bprm);
1631 out:
1632         return ERR_PTR(retval);
1633 }
1634
1635 int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1636 {
1637         /* If a binfmt changed the interp, free it first. */
1638         if (bprm->interp != bprm->filename)
1639                 kfree(bprm->interp);
1640         bprm->interp = kstrdup(interp, GFP_KERNEL);
1641         if (!bprm->interp)
1642                 return -ENOMEM;
1643         return 0;
1644 }
1645 EXPORT_SYMBOL(bprm_change_interp);
1646
1647 /*
1648  * determine how safe it is to execute the proposed program
1649  * - the caller must hold ->cred_guard_mutex to protect against
1650  *   PTRACE_ATTACH or seccomp thread-sync
1651  */
1652 static void check_unsafe_exec(struct linux_binprm *bprm)
1653 {
1654         struct task_struct *p = current, *t;
1655         unsigned n_fs;
1656
1657         if (p->ptrace)
1658                 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1659
1660         /*
1661          * This isn't strictly necessary, but it makes it harder for LSMs to
1662          * mess up.
1663          */
1664         if (task_no_new_privs(current))
1665                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1666
1667         t = p;
1668         n_fs = 1;
1669         spin_lock(&p->fs->lock);
1670         rcu_read_lock();
1671         while_each_thread(p, t) {
1672                 if (t->fs == p->fs)
1673                         n_fs++;
1674         }
1675         rcu_read_unlock();
1676
1677         if (p->fs->users > n_fs)
1678                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1679         else
1680                 p->fs->in_exec = 1;
1681         spin_unlock(&p->fs->lock);
1682 }
1683
1684 static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1685 {
1686         /* Handle suid and sgid on files */
1687         struct inode *inode;
1688         unsigned int mode;
1689         kuid_t uid;
1690         kgid_t gid;
1691
1692         if (!mnt_may_suid(file->f_path.mnt))
1693                 return;
1694
1695         if (task_no_new_privs(current))
1696                 return;
1697
1698         inode = file->f_path.dentry->d_inode;
1699         mode = READ_ONCE(inode->i_mode);
1700         if (!(mode & (S_ISUID|S_ISGID)))
1701                 return;
1702
1703         /* Be careful if suid/sgid is set */
1704         inode_lock(inode);
1705
1706         /* reload atomically mode/uid/gid now that lock held */
1707         mode = inode->i_mode;
1708         uid = inode->i_uid;
1709         gid = inode->i_gid;
1710         inode_unlock(inode);
1711
1712         /* We ignore suid/sgid if there are no mappings for them in the ns */
1713         if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1714                  !kgid_has_mapping(bprm->cred->user_ns, gid))
1715                 return;
1716
1717         if (mode & S_ISUID) {
1718                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1719                 bprm->cred->euid = uid;
1720         }
1721
1722         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1723                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1724                 bprm->cred->egid = gid;
1725         }
1726 }
1727
1728 /*
1729  * Compute brpm->cred based upon the final binary.
1730  */
1731 static int bprm_creds_from_file(struct linux_binprm *bprm)
1732 {
1733         /* Compute creds based on which file? */
1734         struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1735
1736         bprm_fill_uid(bprm, file);
1737         return security_bprm_creds_from_file(bprm, file);
1738 }
1739
1740 /*
1741  * Fill the binprm structure from the inode.
1742  * Read the first BINPRM_BUF_SIZE bytes
1743  *
1744  * This may be called multiple times for binary chains (scripts for example).
1745  */
1746 static int prepare_binprm(struct linux_binprm *bprm)
1747 {
1748         loff_t pos = 0;
1749
1750         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1751         return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1752 }
1753
1754 /*
1755  * Arguments are '\0' separated strings found at the location bprm->p
1756  * points to; chop off the first by relocating brpm->p to right after
1757  * the first '\0' encountered.
1758  */
1759 int remove_arg_zero(struct linux_binprm *bprm)
1760 {
1761         int ret = 0;
1762         unsigned long offset;
1763         char *kaddr;
1764         struct page *page;
1765
1766         if (!bprm->argc)
1767                 return 0;
1768
1769         do {
1770                 offset = bprm->p & ~PAGE_MASK;
1771                 page = get_arg_page(bprm, bprm->p, 0);
1772                 if (!page) {
1773                         ret = -EFAULT;
1774                         goto out;
1775                 }
1776                 kaddr = kmap_atomic(page);
1777
1778                 for (; offset < PAGE_SIZE && kaddr[offset];
1779                                 offset++, bprm->p++)
1780                         ;
1781
1782                 kunmap_atomic(kaddr);
1783                 put_arg_page(page);
1784         } while (offset == PAGE_SIZE);
1785
1786         bprm->p++;
1787         bprm->argc--;
1788         ret = 0;
1789
1790 out:
1791         return ret;
1792 }
1793 EXPORT_SYMBOL(remove_arg_zero);
1794
1795 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1796 /*
1797  * cycle the list of binary formats handler, until one recognizes the image
1798  */
1799 static int search_binary_handler(struct linux_binprm *bprm)
1800 {
1801         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1802         struct linux_binfmt *fmt;
1803         int retval;
1804
1805         retval = prepare_binprm(bprm);
1806         if (retval < 0)
1807                 return retval;
1808
1809         retval = security_bprm_check(bprm);
1810         if (retval)
1811                 return retval;
1812
1813         retval = -ENOENT;
1814  retry:
1815         read_lock(&binfmt_lock);
1816         list_for_each_entry(fmt, &formats, lh) {
1817                 if (!try_module_get(fmt->module))
1818                         continue;
1819                 read_unlock(&binfmt_lock);
1820
1821                 retval = fmt->load_binary(bprm);
1822
1823                 read_lock(&binfmt_lock);
1824                 put_binfmt(fmt);
1825                 if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1826                         read_unlock(&binfmt_lock);
1827                         return retval;
1828                 }
1829         }
1830         read_unlock(&binfmt_lock);
1831
1832         if (need_retry) {
1833                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1834                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1835                         return retval;
1836                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1837                         return retval;
1838                 need_retry = false;
1839                 goto retry;
1840         }
1841
1842         return retval;
1843 }
1844
1845 static int exec_binprm(struct linux_binprm *bprm)
1846 {
1847         pid_t old_pid, old_vpid;
1848         int ret, depth;
1849
1850         /* Need to fetch pid before load_binary changes it */
1851         old_pid = current->pid;
1852         rcu_read_lock();
1853         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1854         rcu_read_unlock();
1855
1856         /* This allows 4 levels of binfmt rewrites before failing hard. */
1857         for (depth = 0;; depth++) {
1858                 struct file *exec;
1859                 if (depth > 5)
1860                         return -ELOOP;
1861
1862                 ret = search_binary_handler(bprm);
1863                 if (ret < 0)
1864                         return ret;
1865                 if (!bprm->interpreter)
1866                         break;
1867
1868                 exec = bprm->file;
1869                 bprm->file = bprm->interpreter;
1870                 bprm->interpreter = NULL;
1871
1872                 allow_write_access(exec);
1873                 if (unlikely(bprm->have_execfd)) {
1874                         if (bprm->executable) {
1875                                 fput(exec);
1876                                 return -ENOEXEC;
1877                         }
1878                         bprm->executable = exec;
1879                 } else
1880                         fput(exec);
1881         }
1882
1883         audit_bprm(bprm);
1884         trace_sched_process_exec(current, old_pid, bprm);
1885         ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1886         proc_exec_connector(current);
1887         return 0;
1888 }
1889
1890 /*
1891  * sys_execve() executes a new program.
1892  */
1893 static int bprm_execve(struct linux_binprm *bprm,
1894                        int fd, struct filename *filename, int flags)
1895 {
1896         struct file *file;
1897         struct files_struct *displaced;
1898         int retval;
1899
1900         retval = unshare_files(&displaced);
1901         if (retval)
1902                 return retval;
1903
1904         retval = prepare_bprm_creds(bprm);
1905         if (retval)
1906                 goto out_files;
1907
1908         check_unsafe_exec(bprm);
1909         current->in_execve = 1;
1910
1911         file = do_open_execat(fd, filename, flags);
1912         retval = PTR_ERR(file);
1913         if (IS_ERR(file))
1914                 goto out_unmark;
1915
1916         sched_exec();
1917
1918         bprm->file = file;
1919         /*
1920          * Record that a name derived from an O_CLOEXEC fd will be
1921          * inaccessible after exec. Relies on having exclusive access to
1922          * current->files (due to unshare_files above).
1923          */
1924         if (bprm->fdpath &&
1925             close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1926                 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1927
1928         /* Set the unchanging part of bprm->cred */
1929         retval = security_bprm_creds_for_exec(bprm);
1930         if (retval)
1931                 goto out;
1932
1933         retval = exec_binprm(bprm);
1934         if (retval < 0)
1935                 goto out;
1936
1937         /* execve succeeded */
1938         current->fs->in_exec = 0;
1939         current->in_execve = 0;
1940         rseq_execve(current);
1941         acct_update_integrals(current);
1942         task_numa_free(current, false);
1943         if (displaced)
1944                 put_files_struct(displaced);
1945         return retval;
1946
1947 out:
1948         /*
1949          * If past the point of no return ensure the the code never
1950          * returns to the userspace process.  Use an existing fatal
1951          * signal if present otherwise terminate the process with
1952          * SIGSEGV.
1953          */
1954         if (bprm->point_of_no_return && !fatal_signal_pending(current))
1955                 force_sigsegv(SIGSEGV);
1956
1957 out_unmark:
1958         current->fs->in_exec = 0;
1959         current->in_execve = 0;
1960
1961 out_files:
1962         if (displaced)
1963                 reset_files_struct(displaced);
1964
1965         return retval;
1966 }
1967
1968 static int do_execveat_common(int fd, struct filename *filename,
1969                               struct user_arg_ptr argv,
1970                               struct user_arg_ptr envp,
1971                               int flags)
1972 {
1973         struct linux_binprm *bprm;
1974         int retval;
1975
1976         if (IS_ERR(filename))
1977                 return PTR_ERR(filename);
1978
1979         /*
1980          * We move the actual failure in case of RLIMIT_NPROC excess from
1981          * set*uid() to execve() because too many poorly written programs
1982          * don't check setuid() return code.  Here we additionally recheck
1983          * whether NPROC limit is still exceeded.
1984          */
1985         if ((current->flags & PF_NPROC_EXCEEDED) &&
1986             atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1987                 retval = -EAGAIN;
1988                 goto out_ret;
1989         }
1990
1991         /* We're below the limit (still or again), so we don't want to make
1992          * further execve() calls fail. */
1993         current->flags &= ~PF_NPROC_EXCEEDED;
1994
1995         bprm = alloc_bprm(fd, filename);
1996         if (IS_ERR(bprm)) {
1997                 retval = PTR_ERR(bprm);
1998                 goto out_ret;
1999         }
2000
2001         retval = count(argv, MAX_ARG_STRINGS);
2002         if (retval < 0)
2003                 goto out_free;
2004         bprm->argc = retval;
2005
2006         retval = count(envp, MAX_ARG_STRINGS);
2007         if (retval < 0)
2008                 goto out_free;
2009         bprm->envc = retval;
2010
2011         retval = bprm_stack_limits(bprm);
2012         if (retval < 0)
2013                 goto out_free;
2014
2015         retval = copy_string_kernel(bprm->filename, bprm);
2016         if (retval < 0)
2017                 goto out_free;
2018         bprm->exec = bprm->p;
2019
2020         retval = copy_strings(bprm->envc, envp, bprm);
2021         if (retval < 0)
2022                 goto out_free;
2023
2024         retval = copy_strings(bprm->argc, argv, bprm);
2025         if (retval < 0)
2026                 goto out_free;
2027
2028         retval = bprm_execve(bprm, fd, filename, flags);
2029 out_free:
2030         free_bprm(bprm);
2031
2032 out_ret:
2033         putname(filename);
2034         return retval;
2035 }
2036
2037 int kernel_execve(const char *kernel_filename,
2038                   const char *const *argv, const char *const *envp)
2039 {
2040         struct filename *filename;
2041         struct linux_binprm *bprm;
2042         int fd = AT_FDCWD;
2043         int retval;
2044
2045         filename = getname_kernel(kernel_filename);
2046         if (IS_ERR(filename))
2047                 return PTR_ERR(filename);
2048
2049         bprm = alloc_bprm(fd, filename);
2050         if (IS_ERR(bprm)) {
2051                 retval = PTR_ERR(bprm);
2052                 goto out_ret;
2053         }
2054
2055         retval = count_strings_kernel(argv);
2056         if (retval < 0)
2057                 goto out_free;
2058         bprm->argc = retval;
2059
2060         retval = count_strings_kernel(envp);
2061         if (retval < 0)
2062                 goto out_free;
2063         bprm->envc = retval;
2064
2065         retval = bprm_stack_limits(bprm);
2066         if (retval < 0)
2067                 goto out_free;
2068
2069         retval = copy_string_kernel(bprm->filename, bprm);
2070         if (retval < 0)
2071                 goto out_free;
2072         bprm->exec = bprm->p;
2073
2074         retval = copy_strings_kernel(bprm->envc, envp, bprm);
2075         if (retval < 0)
2076                 goto out_free;
2077
2078         retval = copy_strings_kernel(bprm->argc, argv, bprm);
2079         if (retval < 0)
2080                 goto out_free;
2081
2082         retval = bprm_execve(bprm, fd, filename, 0);
2083 out_free:
2084         free_bprm(bprm);
2085 out_ret:
2086         putname(filename);
2087         return retval;
2088 }
2089
2090 static int do_execve(struct filename *filename,
2091         const char __user *const __user *__argv,
2092         const char __user *const __user *__envp)
2093 {
2094         struct user_arg_ptr argv = { .ptr.native = __argv };
2095         struct user_arg_ptr envp = { .ptr.native = __envp };
2096         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2097 }
2098
2099 static int do_execveat(int fd, struct filename *filename,
2100                 const char __user *const __user *__argv,
2101                 const char __user *const __user *__envp,
2102                 int flags)
2103 {
2104         struct user_arg_ptr argv = { .ptr.native = __argv };
2105         struct user_arg_ptr envp = { .ptr.native = __envp };
2106
2107         return do_execveat_common(fd, filename, argv, envp, flags);
2108 }
2109
2110 #ifdef CONFIG_COMPAT
2111 static int compat_do_execve(struct filename *filename,
2112         const compat_uptr_t __user *__argv,
2113         const compat_uptr_t __user *__envp)
2114 {
2115         struct user_arg_ptr argv = {
2116                 .is_compat = true,
2117                 .ptr.compat = __argv,
2118         };
2119         struct user_arg_ptr envp = {
2120                 .is_compat = true,
2121                 .ptr.compat = __envp,
2122         };
2123         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2124 }
2125
2126 static int compat_do_execveat(int fd, struct filename *filename,
2127                               const compat_uptr_t __user *__argv,
2128                               const compat_uptr_t __user *__envp,
2129                               int flags)
2130 {
2131         struct user_arg_ptr argv = {
2132                 .is_compat = true,
2133                 .ptr.compat = __argv,
2134         };
2135         struct user_arg_ptr envp = {
2136                 .is_compat = true,
2137                 .ptr.compat = __envp,
2138         };
2139         return do_execveat_common(fd, filename, argv, envp, flags);
2140 }
2141 #endif
2142
2143 void set_binfmt(struct linux_binfmt *new)
2144 {
2145         struct mm_struct *mm = current->mm;
2146
2147         if (mm->binfmt)
2148                 module_put(mm->binfmt->module);
2149
2150         mm->binfmt = new;
2151         if (new)
2152                 __module_get(new->module);
2153 }
2154 EXPORT_SYMBOL(set_binfmt);
2155
2156 /*
2157  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2158  */
2159 void set_dumpable(struct mm_struct *mm, int value)
2160 {
2161         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2162                 return;
2163
2164         set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2165 }
2166
2167 SYSCALL_DEFINE3(execve,
2168                 const char __user *, filename,
2169                 const char __user *const __user *, argv,
2170                 const char __user *const __user *, envp)
2171 {
2172         return do_execve(getname(filename), argv, envp);
2173 }
2174
2175 SYSCALL_DEFINE5(execveat,
2176                 int, fd, const char __user *, filename,
2177                 const char __user *const __user *, argv,
2178                 const char __user *const __user *, envp,
2179                 int, flags)
2180 {
2181         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
2182
2183         return do_execveat(fd,
2184                            getname_flags(filename, lookup_flags, NULL),
2185                            argv, envp, flags);
2186 }
2187
2188 #ifdef CONFIG_COMPAT
2189 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2190         const compat_uptr_t __user *, argv,
2191         const compat_uptr_t __user *, envp)
2192 {
2193         return compat_do_execve(getname(filename), argv, envp);
2194 }
2195
2196 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2197                        const char __user *, filename,
2198                        const compat_uptr_t __user *, argv,
2199                        const compat_uptr_t __user *, envp,
2200                        int,  flags)
2201 {
2202         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
2203
2204         return compat_do_execveat(fd,
2205                                   getname_flags(filename, lookup_flags, NULL),
2206                                   argv, envp, flags);
2207 }
2208 #endif