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/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 #include <linux/syscall_user_dispatch.h>
  67 #include <linux/coredump.h>
  68
  69 #include <linux/uaccess.h>
  70 #include <asm/mmu_context.h>
  71 #include <asm/tlb.h>
  72
  73 #include <trace/events/task.h>
  74 #include "internal.h"
  75
  76 #include <trace/events/sched.h>
  77
  78 static int bprm_creds_from_file(struct linux_binprm *bprm);
  79
  80 int suid_dumpable = 0;
  81
  82 static LIST_HEAD(formats);
  83 static DEFINE_RWLOCK(binfmt_lock);
  84
  85 void __register_binfmt(struct linux_binfmt * fmt, int insert)
  86 {
  87         write_lock(&binfmt_lock);
  88         insert ? list_add(&fmt->lh, &formats) :
  89                  list_add_tail(&fmt->lh, &formats);
  90         write_unlock(&binfmt_lock);
  91 }
  92
  93 EXPORT_SYMBOL(__register_binfmt);
  94
  95 void unregister_binfmt(struct linux_binfmt * fmt)
  96 {
  97         write_lock(&binfmt_lock);
  98         list_del(&fmt->lh);
  99         write_unlock(&binfmt_lock);
 100 }
 101
 102 EXPORT_SYMBOL(unregister_binfmt);
 103
 104 static inline void put_binfmt(struct linux_binfmt * fmt)
 105 {
 106         module_put(fmt->module);
 107 }
 108
 109 bool path_noexec(const struct path *path)
 110 {
 111         return (path->mnt->mnt_flags & MNT_NOEXEC) ||
 112                (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
 113 }
 114
 115 #ifdef CONFIG_USELIB
 116 /*
 117  * Note that a shared library must be both readable and executable due to
 118  * security reasons.
 119  *
 120  * Also note that we take the address to load from the file itself.
 121  */
 122 SYSCALL_DEFINE1(uselib, const char __user *, library)
 123 {
 124         struct linux_binfmt *fmt;
 125         struct file *file;
 126         struct filename *tmp = getname(library);
 127         int error = PTR_ERR(tmp);
 128         static const struct open_flags uselib_flags = {
 129                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 130                 .acc_mode = MAY_READ | MAY_EXEC,
 131                 .intent = LOOKUP_OPEN,
 132                 .lookup_flags = LOOKUP_FOLLOW,
 133         };
 134
 135         if (IS_ERR(tmp))
 136                 goto out;
 137
 138         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 139         putname(tmp);
 140         error = PTR_ERR(file);
 141         if (IS_ERR(file))
 142                 goto out;
 143
 144         /*
 145          * may_open() has already checked for this, so it should be
 146          * impossible to trip now. But we need to be extra cautious
 147          * and check again at the very end too.
 148          */
 149         error = -EACCES;
 150         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 151                          path_noexec(&file->f_path)))
 152                 goto exit;
 153
 154         fsnotify_open(file);
 155
 156         error = -ENOEXEC;
 157
 158         read_lock(&binfmt_lock);
 159         list_for_each_entry(fmt, &formats, lh) {
 160                 if (!fmt->load_shlib)
 161                         continue;
 162                 if (!try_module_get(fmt->module))
 163                         continue;
 164                 read_unlock(&binfmt_lock);
 165                 error = fmt->load_shlib(file);
 166                 read_lock(&binfmt_lock);
 167                 put_binfmt(fmt);
 168                 if (error != -ENOEXEC)
 169                         break;
 170         }
 171         read_unlock(&binfmt_lock);
 172 exit:
 173         fput(file);
 174 out:
 175         return error;
 176 }
 177 #endif /* #ifdef CONFIG_USELIB */
 178
 179 #ifdef CONFIG_MMU
 180 /*
 181  * The nascent bprm->mm is not visible until exec_mmap() but it can
 182  * use a lot of memory, account these pages in current->mm temporary
 183  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 184  * change the counter back via acct_arg_size(0).
 185  */
 186 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 187 {
 188         struct mm_struct *mm = current->mm;
 189         long diff = (long)(pages - bprm->vma_pages);
 190
 191         if (!mm || !diff)
 192                 return;
 193
 194         bprm->vma_pages = pages;
 195         add_mm_counter(mm, MM_ANONPAGES, diff);
 196 }
 197
 198 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 199                 int write)
 200 {
 201         struct page *page;
 202         int ret;
 203         unsigned int gup_flags = FOLL_FORCE;
 204
 205 #ifdef CONFIG_STACK_GROWSUP
 206         if (write) {
 207                 ret = expand_downwards(bprm->vma, pos);
 208                 if (ret < 0)
 209                         return NULL;
 210         }
 211 #endif
 212
 213         if (write)
 214                 gup_flags |= FOLL_WRITE;
 215
 216         /*
 217          * We are doing an exec().  'current' is the process
 218          * doing the exec and bprm->mm is the new process's mm.
 219          */
 220         mmap_read_lock(bprm->mm);
 221         ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
 222                         &page, NULL, NULL);
 223         mmap_read_unlock(bprm->mm);
 224         if (ret <= 0)
 225                 return NULL;
 226
 227         if (write)
 228                 acct_arg_size(bprm, vma_pages(bprm->vma));
 229
 230         return page;
 231 }
 232
 233 static void put_arg_page(struct page *page)
 234 {
 235         put_page(page);
 236 }
 237
 238 static void free_arg_pages(struct linux_binprm *bprm)
 239 {
 240 }
 241
 242 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 243                 struct page *page)
 244 {
 245         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 246 }
 247
 248 static int __bprm_mm_init(struct linux_binprm *bprm)
 249 {
 250         int err;
 251         struct vm_area_struct *vma = NULL;
 252         struct mm_struct *mm = bprm->mm;
 253
 254         bprm->vma = vma = vm_area_alloc(mm);
 255         if (!vma)
 256                 return -ENOMEM;
 257         vma_set_anonymous(vma);
 258
 259         if (mmap_write_lock_killable(mm)) {
 260                 err = -EINTR;
 261                 goto err_free;
 262         }
 263
 264         /*
 265          * Place the stack at the largest stack address the architecture
 266          * supports. Later, we'll move this to an appropriate place. We don't
 267          * use STACK_TOP because that can depend on attributes which aren't
 268          * configured yet.
 269          */
 270         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 271         vma->vm_end = STACK_TOP_MAX;
 272         vma->vm_start = vma->vm_end - PAGE_SIZE;
 273         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 274         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 275
 276         err = insert_vm_struct(mm, vma);
 277         if (err)
 278                 goto err;
 279
 280         mm->stack_vm = mm->total_vm = 1;
 281         mmap_write_unlock(mm);
 282         bprm->p = vma->vm_end - sizeof(void *);
 283         return 0;
 284 err:
 285         mmap_write_unlock(mm);
 286 err_free:
 287         bprm->vma = NULL;
 288         vm_area_free(vma);
 289         return err;
 290 }
 291
 292 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 293 {
 294         return len <= MAX_ARG_STRLEN;
 295 }
 296
 297 #else
 298
 299 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 300 {
 301 }
 302
 303 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 304                 int write)
 305 {
 306         struct page *page;
 307
 308         page = bprm->page[pos / PAGE_SIZE];
 309         if (!page && write) {
 310                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
 311                 if (!page)
 312                         return NULL;
 313                 bprm->page[pos / PAGE_SIZE] = page;
 314         }
 315
 316         return page;
 317 }
 318
 319 static void put_arg_page(struct page *page)
 320 {
 321 }
 322
 323 static void free_arg_page(struct linux_binprm *bprm, int i)
 324 {
 325         if (bprm->page[i]) {
 326                 __free_page(bprm->page[i]);
 327                 bprm->page[i] = NULL;
 328         }
 329 }
 330
 331 static void free_arg_pages(struct linux_binprm *bprm)
 332 {
 333         int i;
 334
 335         for (i = 0; i < MAX_ARG_PAGES; i++)
 336                 free_arg_page(bprm, i);
 337 }
 338
 339 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 340                 struct page *page)
 341 {
 342 }
 343
 344 static int __bprm_mm_init(struct linux_binprm *bprm)
 345 {
 346         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
 347         return 0;
 348 }
 349
 350 static bool valid_arg_len(struct linux_binprm *bprm, long len)
 351 {
 352         return len <= bprm->p;
 353 }
 354
 355 #endif /* CONFIG_MMU */
 356
 357 /*
 358  * Create a new mm_struct and populate it with a temporary stack
 359  * vm_area_struct.  We don't have enough context at this point to set the stack
 360  * flags, permissions, and offset, so we use temporary values.  We'll update
 361  * them later in setup_arg_pages().
 362  */
 363 static int bprm_mm_init(struct linux_binprm *bprm)
 364 {
 365         int err;
 366         struct mm_struct *mm = NULL;
 367
 368         bprm->mm = mm = mm_alloc();
 369         err = -ENOMEM;
 370         if (!mm)
 371                 goto err;
 372
 373         /* Save current stack limit for all calculations made during exec. */
 374         task_lock(current->group_leader);
 375         bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
 376         task_unlock(current->group_leader);
 377
 378         err = __bprm_mm_init(bprm);
 379         if (err)
 380                 goto err;
 381
 382         return 0;
 383
 384 err:
 385         if (mm) {
 386                 bprm->mm = NULL;
 387                 mmdrop(mm);
 388         }
 389
 390         return err;
 391 }
 392
 393 struct user_arg_ptr {
 394 #ifdef CONFIG_COMPAT
 395         bool is_compat;
 396 #endif
 397         union {
 398                 const char __user *const __user *native;
 399 #ifdef CONFIG_COMPAT
 400                 const compat_uptr_t __user *compat;
 401 #endif
 402         } ptr;
 403 };
 404
 405 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 406 {
 407         const char __user *native;
 408
 409 #ifdef CONFIG_COMPAT
 410         if (unlikely(argv.is_compat)) {
 411                 compat_uptr_t compat;
 412
 413                 if (get_user(compat, argv.ptr.compat + nr))
 414                         return ERR_PTR(-EFAULT);
 415
 416                 return compat_ptr(compat);
 417         }
 418 #endif
 419
 420         if (get_user(native, argv.ptr.native + nr))
 421                 return ERR_PTR(-EFAULT);
 422
 423         return native;
 424 }
 425
 426 /*
 427  * count() counts the number of strings in array ARGV.
 428  */
 429 static int count(struct user_arg_ptr argv, int max)
 430 {
 431         int i = 0;
 432
 433         if (argv.ptr.native != NULL) {
 434                 for (;;) {
 435                         const char __user *p = get_user_arg_ptr(argv, i);
 436
 437                         if (!p)
 438                                 break;
 439
 440                         if (IS_ERR(p))
 441                                 return -EFAULT;
 442
 443                         if (i >= max)
 444                                 return -E2BIG;
 445                         ++i;
 446
 447                         if (fatal_signal_pending(current))
 448                                 return -ERESTARTNOHAND;
 449                         cond_resched();
 450                 }
 451         }
 452         return i;
 453 }
 454
 455 static int count_strings_kernel(const char *const *argv)
 456 {
 457         int i;
 458
 459         if (!argv)
 460                 return 0;
 461
 462         for (i = 0; argv[i]; ++i) {
 463                 if (i >= MAX_ARG_STRINGS)
 464                         return -E2BIG;
 465                 if (fatal_signal_pending(current))
 466                         return -ERESTARTNOHAND;
 467                 cond_resched();
 468         }
 469         return i;
 470 }
 471
 472 static int bprm_stack_limits(struct linux_binprm *bprm)
 473 {
 474         unsigned long limit, ptr_size;
 475
 476         /*
 477          * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
 478          * (whichever is smaller) for the argv+env strings.
 479          * This ensures that:
 480          *  - the remaining binfmt code will not run out of stack space,
 481          *  - the program will have a reasonable amount of stack left
 482          *    to work from.
 483          */
 484         limit = _STK_LIM / 4 * 3;
 485         limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
 486         /*
 487          * We've historically supported up to 32 pages (ARG_MAX)
 488          * of argument strings even with small stacks
 489          */
 490         limit = max_t(unsigned long, limit, ARG_MAX);
 491         /*
 492          * We must account for the size of all the argv and envp pointers to
 493          * the argv and envp strings, since they will also take up space in
 494          * the stack. They aren't stored until much later when we can't
 495          * signal to the parent that the child has run out of stack space.
 496          * Instead, calculate it here so it's possible to fail gracefully.
 497          *
 498          * In the case of argc = 0, make sure there is space for adding a
 499          * empty string (which will bump argc to 1), to ensure confused
 500          * userspace programs don't start processing from argv[1], thinking
 501          * argc can never be 0, to keep them from walking envp by accident.
 502          * See do_execveat_common().
 503          */
 504         ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
 505         if (limit <= ptr_size)
 506                 return -E2BIG;
 507         limit -= ptr_size;
 508
 509         bprm->argmin = bprm->p - limit;
 510         return 0;
 511 }
 512
 513 /*
 514  * 'copy_strings()' copies argument/environment strings from the old
 515  * processes's memory to the new process's stack.  The call to get_user_pages()
 516  * ensures the destination page is created and not swapped out.
 517  */
 518 static int copy_strings(int argc, struct user_arg_ptr argv,
 519                         struct linux_binprm *bprm)
 520 {
 521         struct page *kmapped_page = NULL;
 522         char *kaddr = NULL;
 523         unsigned long kpos = 0;
 524         int ret;
 525
 526         while (argc-- > 0) {
 527                 const char __user *str;
 528                 int len;
 529                 unsigned long pos;
 530
 531                 ret = -EFAULT;
 532                 str = get_user_arg_ptr(argv, argc);
 533                 if (IS_ERR(str))
 534                         goto out;
 535
 536                 len = strnlen_user(str, MAX_ARG_STRLEN);
 537                 if (!len)
 538                         goto out;
 539
 540                 ret = -E2BIG;
 541                 if (!valid_arg_len(bprm, len))
 542                         goto out;
 543
 544                 /* We're going to work our way backwards. */
 545                 pos = bprm->p;
 546                 str += len;
 547                 bprm->p -= len;
 548 #ifdef CONFIG_MMU
 549                 if (bprm->p < bprm->argmin)
 550                         goto out;
 551 #endif
 552
 553                 while (len > 0) {
 554                         int offset, bytes_to_copy;
 555
 556                         if (fatal_signal_pending(current)) {
 557                                 ret = -ERESTARTNOHAND;
 558                                 goto out;
 559                         }
 560                         cond_resched();
 561
 562                         offset = pos % PAGE_SIZE;
 563                         if (offset == 0)
 564                                 offset = PAGE_SIZE;
 565
 566                         bytes_to_copy = offset;
 567                         if (bytes_to_copy > len)
 568                                 bytes_to_copy = len;
 569
 570                         offset -= bytes_to_copy;
 571                         pos -= bytes_to_copy;
 572                         str -= bytes_to_copy;
 573                         len -= bytes_to_copy;
 574
 575                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 576                                 struct page *page;
 577
 578                                 page = get_arg_page(bprm, pos, 1);
 579                                 if (!page) {
 580                                         ret = -E2BIG;
 581                                         goto out;
 582                                 }
 583
 584                                 if (kmapped_page) {
 585                                         flush_dcache_page(kmapped_page);
 586                                         kunmap(kmapped_page);
 587                                         put_arg_page(kmapped_page);
 588                                 }
 589                                 kmapped_page = page;
 590                                 kaddr = kmap(kmapped_page);
 591                                 kpos = pos & PAGE_MASK;
 592                                 flush_arg_page(bprm, kpos, kmapped_page);
 593                         }
 594                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 595                                 ret = -EFAULT;
 596                                 goto out;
 597                         }
 598                 }
 599         }
 600         ret = 0;
 601 out:
 602         if (kmapped_page) {
 603                 flush_dcache_page(kmapped_page);
 604                 kunmap(kmapped_page);
 605                 put_arg_page(kmapped_page);
 606         }
 607         return ret;
 608 }
 609
 610 /*
 611  * Copy and argument/environment string from the kernel to the processes stack.
 612  */
 613 int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
 614 {
 615         int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
 616         unsigned long pos = bprm->p;
 617
 618         if (len == 0)
 619                 return -EFAULT;
 620         if (!valid_arg_len(bprm, len))
 621                 return -E2BIG;
 622
 623         /* We're going to work our way backwards. */
 624         arg += len;
 625         bprm->p -= len;
 626         if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
 627                 return -E2BIG;
 628
 629         while (len > 0) {
 630                 unsigned int bytes_to_copy = min_t(unsigned int, len,
 631                                 min_not_zero(offset_in_page(pos), PAGE_SIZE));
 632                 struct page *page;
 633                 char *kaddr;
 634
 635                 pos -= bytes_to_copy;
 636                 arg -= bytes_to_copy;
 637                 len -= bytes_to_copy;
 638
 639                 page = get_arg_page(bprm, pos, 1);
 640                 if (!page)
 641                         return -E2BIG;
 642                 kaddr = kmap_atomic(page);
 643                 flush_arg_page(bprm, pos & PAGE_MASK, page);
 644                 memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy);
 645                 flush_dcache_page(page);
 646                 kunmap_atomic(kaddr);
 647                 put_arg_page(page);
 648         }
 649
 650         return 0;
 651 }
 652 EXPORT_SYMBOL(copy_string_kernel);
 653
 654 static int copy_strings_kernel(int argc, const char *const *argv,
 655                                struct linux_binprm *bprm)
 656 {
 657         while (argc-- > 0) {
 658                 int ret = copy_string_kernel(argv[argc], bprm);
 659                 if (ret < 0)
 660                         return ret;
 661                 if (fatal_signal_pending(current))
 662                         return -ERESTARTNOHAND;
 663                 cond_resched();
 664         }
 665         return 0;
 666 }
 667
 668 #ifdef CONFIG_MMU
 669
 670 /*
 671  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 672  * the binfmt code determines where the new stack should reside, we shift it to
 673  * its final location.  The process proceeds as follows:
 674  *
 675  * 1) Use shift to calculate the new vma endpoints.
 676  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 677  *    arguments passed to subsequent functions are consistent.
 678  * 3) Move vma's page tables to the new range.
 679  * 4) Free up any cleared pgd range.
 680  * 5) Shrink the vma to cover only the new range.
 681  */
 682 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 683 {
 684         struct mm_struct *mm = vma->vm_mm;
 685         unsigned long old_start = vma->vm_start;
 686         unsigned long old_end = vma->vm_end;
 687         unsigned long length = old_end - old_start;
 688         unsigned long new_start = old_start - shift;
 689         unsigned long new_end = old_end - shift;
 690         struct mmu_gather tlb;
 691
 692         BUG_ON(new_start > new_end);
 693
 694         /*
 695          * ensure there are no vmas between where we want to go
 696          * and where we are
 697          */
 698         if (vma != find_vma(mm, new_start))
 699                 return -EFAULT;
 700
 701         /*
 702          * cover the whole range: [new_start, old_end)
 703          */
 704         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 705                 return -ENOMEM;
 706
 707         /*
 708          * move the page tables downwards, on failure we rely on
 709          * process cleanup to remove whatever mess we made.
 710          */
 711         if (length != move_page_tables(vma, old_start,
 712                                        vma, new_start, length, false))
 713                 return -ENOMEM;
 714
 715         lru_add_drain();
 716         tlb_gather_mmu(&tlb, mm);
 717         if (new_end > old_start) {
 718                 /*
 719                  * when the old and new regions overlap clear from new_end.
 720                  */
 721                 free_pgd_range(&tlb, new_end, old_end, new_end,
 722                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 723         } else {
 724                 /*
 725                  * otherwise, clean from old_start; this is done to not touch
 726                  * the address space in [new_end, old_start) some architectures
 727                  * have constraints on va-space that make this illegal (IA64) -
 728                  * for the others its just a little faster.
 729                  */
 730                 free_pgd_range(&tlb, old_start, old_end, new_end,
 731                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 732         }
 733         tlb_finish_mmu(&tlb);
 734
 735         /*
 736          * Shrink the vma to just the new range.  Always succeeds.
 737          */
 738         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 739
 740         return 0;
 741 }
 742
 743 /*
 744  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 745  * the stack is optionally relocated, and some extra space is added.
 746  */
 747 int setup_arg_pages(struct linux_binprm *bprm,
 748                     unsigned long stack_top,
 749                     int executable_stack)
 750 {
 751         unsigned long ret;
 752         unsigned long stack_shift;
 753         struct mm_struct *mm = current->mm;
 754         struct vm_area_struct *vma = bprm->vma;
 755         struct vm_area_struct *prev = NULL;
 756         unsigned long vm_flags;
 757         unsigned long stack_base;
 758         unsigned long stack_size;
 759         unsigned long stack_expand;
 760         unsigned long rlim_stack;
 761         struct mmu_gather tlb;
 762
 763 #ifdef CONFIG_STACK_GROWSUP
 764         /* Limit stack size */
 765         stack_base = bprm->rlim_stack.rlim_max;
 766
 767         stack_base = calc_max_stack_size(stack_base);
 768
 769         /* Add space for stack randomization. */
 770         stack_base += (STACK_RND_MASK << PAGE_SHIFT);
 771
 772         /* Make sure we didn't let the argument array grow too large. */
 773         if (vma->vm_end - vma->vm_start > stack_base)
 774                 return -ENOMEM;
 775
 776         stack_base = PAGE_ALIGN(stack_top - stack_base);
 777
 778         stack_shift = vma->vm_start - stack_base;
 779         mm->arg_start = bprm->p - stack_shift;
 780         bprm->p = vma->vm_end - stack_shift;
 781 #else
 782         stack_top = arch_align_stack(stack_top);
 783         stack_top = PAGE_ALIGN(stack_top);
 784
 785         if (unlikely(stack_top < mmap_min_addr) ||
 786             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 787                 return -ENOMEM;
 788
 789         stack_shift = vma->vm_end - stack_top;
 790
 791         bprm->p -= stack_shift;
 792         mm->arg_start = bprm->p;
 793 #endif
 794
 795         if (bprm->loader)
 796                 bprm->loader -= stack_shift;
 797         bprm->exec -= stack_shift;
 798
 799         if (mmap_write_lock_killable(mm))
 800                 return -EINTR;
 801
 802         vm_flags = VM_STACK_FLAGS;
 803
 804         /*
 805          * Adjust stack execute permissions; explicitly enable for
 806          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 807          * (arch default) otherwise.
 808          */
 809         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 810                 vm_flags |= VM_EXEC;
 811         else if (executable_stack == EXSTACK_DISABLE_X)
 812                 vm_flags &= ~VM_EXEC;
 813         vm_flags |= mm->def_flags;
 814         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 815
 816         tlb_gather_mmu(&tlb, mm);
 817         ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,
 818                         vm_flags);
 819         tlb_finish_mmu(&tlb);
 820
 821         if (ret)
 822                 goto out_unlock;
 823         BUG_ON(prev != vma);
 824
 825         if (unlikely(vm_flags & VM_EXEC)) {
 826                 pr_warn_once("process '%pD4' started with executable stack\n",
 827                              bprm->file);
 828         }
 829
 830         /* Move stack pages down in memory. */
 831         if (stack_shift) {
 832                 ret = shift_arg_pages(vma, stack_shift);
 833                 if (ret)
 834                         goto out_unlock;
 835         }
 836
 837         /* mprotect_fixup is overkill to remove the temporary stack flags */
 838         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 839
 840         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 841         stack_size = vma->vm_end - vma->vm_start;
 842         /*
 843          * Align this down to a page boundary as expand_stack
 844          * will align it up.
 845          */
 846         rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
 847 #ifdef CONFIG_STACK_GROWSUP
 848         if (stack_size + stack_expand > rlim_stack)
 849                 stack_base = vma->vm_start + rlim_stack;
 850         else
 851                 stack_base = vma->vm_end + stack_expand;
 852 #else
 853         if (stack_size + stack_expand > rlim_stack)
 854                 stack_base = vma->vm_end - rlim_stack;
 855         else
 856                 stack_base = vma->vm_start - stack_expand;
 857 #endif
 858         current->mm->start_stack = bprm->p;
 859         ret = expand_stack(vma, stack_base);
 860         if (ret)
 861                 ret = -EFAULT;
 862
 863 out_unlock:
 864         mmap_write_unlock(mm);
 865         return ret;
 866 }
 867 EXPORT_SYMBOL(setup_arg_pages);
 868
 869 #else
 870
 871 /*
 872  * Transfer the program arguments and environment from the holding pages
 873  * onto the stack. The provided stack pointer is adjusted accordingly.
 874  */
 875 int transfer_args_to_stack(struct linux_binprm *bprm,
 876                            unsigned long *sp_location)
 877 {
 878         unsigned long index, stop, sp;
 879         int ret = 0;
 880
 881         stop = bprm->p >> PAGE_SHIFT;
 882         sp = *sp_location;
 883
 884         for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
 885                 unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
 886                 char *src = kmap(bprm->page[index]) + offset;
 887                 sp -= PAGE_SIZE - offset;
 888                 if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
 889                         ret = -EFAULT;
 890                 kunmap(bprm->page[index]);
 891                 if (ret)
 892                         goto out;
 893         }
 894
 895         *sp_location = sp;
 896
 897 out:
 898         return ret;
 899 }
 900 EXPORT_SYMBOL(transfer_args_to_stack);
 901
 902 #endif /* CONFIG_MMU */
 903
 904 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 905 {
 906         struct file *file;
 907         int err;
 908         struct open_flags open_exec_flags = {
 909                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 910                 .acc_mode = MAY_EXEC,
 911                 .intent = LOOKUP_OPEN,
 912                 .lookup_flags = LOOKUP_FOLLOW,
 913         };
 914
 915         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 916                 return ERR_PTR(-EINVAL);
 917         if (flags & AT_SYMLINK_NOFOLLOW)
 918                 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 919         if (flags & AT_EMPTY_PATH)
 920                 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 921
 922         file = do_filp_open(fd, name, &open_exec_flags);
 923         if (IS_ERR(file))
 924                 goto out;
 925
 926         /*
 927          * may_open() has already checked for this, so it should be
 928          * impossible to trip now. But we need to be extra cautious
 929          * and check again at the very end too.
 930          */
 931         err = -EACCES;
 932         if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
 933                          path_noexec(&file->f_path)))
 934                 goto exit;
 935
 936         err = deny_write_access(file);
 937         if (err)
 938                 goto exit;
 939
 940         if (name->name[0] != '\0')
 941                 fsnotify_open(file);
 942
 943 out:
 944         return file;
 945
 946 exit:
 947         fput(file);
 948         return ERR_PTR(err);
 949 }
 950
 951 struct file *open_exec(const char *name)
 952 {
 953         struct filename *filename = getname_kernel(name);
 954         struct file *f = ERR_CAST(filename);
 955
 956         if (!IS_ERR(filename)) {
 957                 f = do_open_execat(AT_FDCWD, filename, 0);
 958                 putname(filename);
 959         }
 960         return f;
 961 }
 962 EXPORT_SYMBOL(open_exec);
 963
 964 #if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
 965     defined(CONFIG_BINFMT_ELF_FDPIC)
 966 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 967 {
 968         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 969         if (res > 0)
 970                 flush_icache_user_range(addr, addr + len);
 971         return res;
 972 }
 973 EXPORT_SYMBOL(read_code);
 974 #endif
 975
 976 /*
 977  * Maps the mm_struct mm into the current task struct.
 978  * On success, this function returns with exec_update_lock
 979  * held for writing.
 980  */
 981 static int exec_mmap(struct mm_struct *mm)
 982 {
 983         struct task_struct *tsk;
 984         struct mm_struct *old_mm, *active_mm;
 985         int ret;
 986
 987         /* Notify parent that we're no longer interested in the old VM */
 988         tsk = current;
 989         old_mm = current->mm;
 990         exec_mm_release(tsk, old_mm);
 991         if (old_mm)
 992                 sync_mm_rss(old_mm);
 993
 994         ret = down_write_killable(&tsk->signal->exec_update_lock);
 995         if (ret)
 996                 return ret;
 997
 998         if (old_mm) {
 999                 /*
1000                  * If there is a pending fatal signal perhaps a signal
1001                  * whose default action is to create a coredump get
1002                  * out and die instead of going through with the exec.
1003                  */
1004                 ret = mmap_read_lock_killable(old_mm);
1005                 if (ret) {
1006                         up_write(&tsk->signal->exec_update_lock);
1007                         return ret;
1008                 }
1009         }
1010
1011         task_lock(tsk);
1012         membarrier_exec_mmap(mm);
1013
1014         local_irq_disable();
1015         active_mm = tsk->active_mm;
1016         tsk->active_mm = mm;
1017         tsk->mm = mm;
1018         /*
1019          * This prevents preemption while active_mm is being loaded and
1020          * it and mm are being updated, which could cause problems for
1021          * lazy tlb mm refcounting when these are updated by context
1022          * switches. Not all architectures can handle irqs off over
1023          * activate_mm yet.
1024          */
1025         if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1026                 local_irq_enable();
1027         activate_mm(active_mm, mm);
1028         if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1029                 local_irq_enable();
1030         tsk->mm->vmacache_seqnum = 0;
1031         vmacache_flush(tsk);
1032         task_unlock(tsk);
1033         if (old_mm) {
1034                 mmap_read_unlock(old_mm);
1035                 BUG_ON(active_mm != old_mm);
1036                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1037                 mm_update_next_owner(old_mm);
1038                 mmput(old_mm);
1039                 return 0;
1040         }
1041         mmdrop(active_mm);
1042         return 0;
1043 }
1044
1045 static int de_thread(struct task_struct *tsk)
1046 {
1047         struct signal_struct *sig = tsk->signal;
1048         struct sighand_struct *oldsighand = tsk->sighand;
1049         spinlock_t *lock = &oldsighand->siglock;
1050
1051         if (thread_group_empty(tsk))
1052                 goto no_thread_group;
1053
1054         /*
1055          * Kill all other threads in the thread group.
1056          */
1057         spin_lock_irq(lock);
1058         if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1059                 /*
1060                  * Another group action in progress, just
1061                  * return so that the signal is processed.
1062                  */
1063                 spin_unlock_irq(lock);
1064                 return -EAGAIN;
1065         }
1066
1067         sig->group_exec_task = tsk;
1068         sig->notify_count = zap_other_threads(tsk);
1069         if (!thread_group_leader(tsk))
1070                 sig->notify_count--;
1071
1072         while (sig->notify_count) {
1073                 __set_current_state(TASK_KILLABLE);
1074                 spin_unlock_irq(lock);
1075                 schedule();
1076                 if (__fatal_signal_pending(tsk))
1077                         goto killed;
1078                 spin_lock_irq(lock);
1079         }
1080         spin_unlock_irq(lock);
1081
1082         /*
1083          * At this point all other threads have exited, all we have to
1084          * do is to wait for the thread group leader to become inactive,
1085          * and to assume its PID:
1086          */
1087         if (!thread_group_leader(tsk)) {
1088                 struct task_struct *leader = tsk->group_leader;
1089
1090                 for (;;) {
1091                         cgroup_threadgroup_change_begin(tsk);
1092                         write_lock_irq(&tasklist_lock);
1093                         /*
1094                          * Do this under tasklist_lock to ensure that
1095                          * exit_notify() can't miss ->group_exec_task
1096                          */
1097                         sig->notify_count = -1;
1098                         if (likely(leader->exit_state))
1099                                 break;
1100                         __set_current_state(TASK_KILLABLE);
1101                         write_unlock_irq(&tasklist_lock);
1102                         cgroup_threadgroup_change_end(tsk);
1103                         schedule();
1104                         if (__fatal_signal_pending(tsk))
1105                                 goto killed;
1106                 }
1107
1108                 /*
1109                  * The only record we have of the real-time age of a
1110                  * process, regardless of execs it's done, is start_time.
1111                  * All the past CPU time is accumulated in signal_struct
1112                  * from sister threads now dead.  But in this non-leader
1113                  * exec, nothing survives from the original leader thread,
1114                  * whose birth marks the true age of this process now.
1115                  * When we take on its identity by switching to its PID, we
1116                  * also take its birthdate (always earlier than our own).
1117                  */
1118                 tsk->start_time = leader->start_time;
1119                 tsk->start_boottime = leader->start_boottime;
1120
1121                 BUG_ON(!same_thread_group(leader, tsk));
1122                 /*
1123                  * An exec() starts a new thread group with the
1124                  * TGID of the previous thread group. Rehash the
1125                  * two threads with a switched PID, and release
1126                  * the former thread group leader:
1127                  */
1128
1129                 /* Become a process group leader with the old leader's pid.
1130                  * The old leader becomes a thread of the this thread group.
1131                  */
1132                 exchange_tids(tsk, leader);
1133                 transfer_pid(leader, tsk, PIDTYPE_TGID);
1134                 transfer_pid(leader, tsk, PIDTYPE_PGID);
1135                 transfer_pid(leader, tsk, PIDTYPE_SID);
1136
1137                 list_replace_rcu(&leader->tasks, &tsk->tasks);
1138                 list_replace_init(&leader->sibling, &tsk->sibling);
1139
1140                 tsk->group_leader = tsk;
1141                 leader->group_leader = tsk;
1142
1143                 tsk->exit_signal = SIGCHLD;
1144                 leader->exit_signal = -1;
1145
1146                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1147                 leader->exit_state = EXIT_DEAD;
1148
1149                 /*
1150                  * We are going to release_task()->ptrace_unlink() silently,
1151                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1152                  * the tracer wont't block again waiting for this thread.
1153                  */
1154                 if (unlikely(leader->ptrace))
1155                         __wake_up_parent(leader, leader->parent);
1156                 write_unlock_irq(&tasklist_lock);
1157                 cgroup_threadgroup_change_end(tsk);
1158
1159                 release_task(leader);
1160         }
1161
1162         sig->group_exec_task = NULL;
1163         sig->notify_count = 0;
1164
1165 no_thread_group:
1166         /* we have changed execution domain */
1167         tsk->exit_signal = SIGCHLD;
1168
1169         BUG_ON(!thread_group_leader(tsk));
1170         return 0;
1171
1172 killed:
1173         /* protects against exit_notify() and __exit_signal() */
1174         read_lock(&tasklist_lock);
1175         sig->group_exec_task = NULL;
1176         sig->notify_count = 0;
1177         read_unlock(&tasklist_lock);
1178         return -EAGAIN;
1179 }
1180
1181
1182 /*
1183  * This function makes sure the current process has its own signal table,
1184  * so that flush_signal_handlers can later reset the handlers without
1185  * disturbing other processes.  (Other processes might share the signal
1186  * table via the CLONE_SIGHAND option to clone().)
1187  */
1188 static int unshare_sighand(struct task_struct *me)
1189 {
1190         struct sighand_struct *oldsighand = me->sighand;
1191
1192         if (refcount_read(&oldsighand->count) != 1) {
1193                 struct sighand_struct *newsighand;
1194                 /*
1195                  * This ->sighand is shared with the CLONE_SIGHAND
1196                  * but not CLONE_THREAD task, switch to the new one.
1197                  */
1198                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1199                 if (!newsighand)
1200                         return -ENOMEM;
1201
1202                 refcount_set(&newsighand->count, 1);
1203                 memcpy(newsighand->action, oldsighand->action,
1204                        sizeof(newsighand->action));
1205
1206                 write_lock_irq(&tasklist_lock);
1207                 spin_lock(&oldsighand->siglock);
1208                 rcu_assign_pointer(me->sighand, newsighand);
1209                 spin_unlock(&oldsighand->siglock);
1210                 write_unlock_irq(&tasklist_lock);
1211
1212                 __cleanup_sighand(oldsighand);
1213         }
1214         return 0;
1215 }
1216
1217 char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1218 {
1219         task_lock(tsk);
1220         /* Always NUL terminated and zero-padded */
1221         strscpy_pad(buf, tsk->comm, buf_size);
1222         task_unlock(tsk);
1223         return buf;
1224 }
1225 EXPORT_SYMBOL_GPL(__get_task_comm);
1226
1227 /*
1228  * These functions flushes out all traces of the currently running executable
1229  * so that a new one can be started
1230  */
1231
1232 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1233 {
1234         task_lock(tsk);
1235         trace_task_rename(tsk, buf);
1236         strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1237         task_unlock(tsk);
1238         perf_event_comm(tsk, exec);
1239 }
1240
1241 /*
1242  * Calling this is the point of no return. None of the failures will be
1243  * seen by userspace since either the process is already taking a fatal
1244  * signal (via de_thread() or coredump), or will have SEGV raised
1245  * (after exec_mmap()) by search_binary_handler (see below).
1246  */
1247 int begin_new_exec(struct linux_binprm * bprm)
1248 {
1249         struct task_struct *me = current;
1250         int retval;
1251
1252         /* Once we are committed compute the creds */
1253         retval = bprm_creds_from_file(bprm);
1254         if (retval)
1255                 return retval;
1256
1257         /*
1258          * Ensure all future errors are fatal.
1259          */
1260         bprm->point_of_no_return = true;
1261
1262         /*
1263          * Make this the only thread in the thread group.
1264          */
1265         retval = de_thread(me);
1266         if (retval)
1267                 goto out;
1268
1269         /*
1270          * Cancel any io_uring activity across execve
1271          */
1272         io_uring_task_cancel();
1273
1274         /* Ensure the files table is not shared. */
1275         retval = unshare_files();
1276         if (retval)
1277                 goto out;
1278
1279         /*
1280          * Must be called _before_ exec_mmap() as bprm->mm is
1281          * not visible until then. This also enables the update
1282          * to be lockless.
1283          */
1284         retval = set_mm_exe_file(bprm->mm, bprm->file);
1285         if (retval)
1286                 goto out;
1287
1288         /* If the binary is not readable then enforce mm->dumpable=0 */
1289         would_dump(bprm, bprm->file);
1290         if (bprm->have_execfd)
1291                 would_dump(bprm, bprm->executable);
1292
1293         /*
1294          * Release all of the old mmap stuff
1295          */
1296         acct_arg_size(bprm, 0);
1297         retval = exec_mmap(bprm->mm);
1298         if (retval)
1299                 goto out;
1300
1301         bprm->mm = NULL;
1302
1303 #ifdef CONFIG_POSIX_TIMERS
1304         exit_itimers(me);
1305         flush_itimer_signals();
1306 #endif
1307
1308         /*
1309          * Make the signal table private.
1310          */
1311         retval = unshare_sighand(me);
1312         if (retval)
1313                 goto out_unlock;
1314
1315         me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1316                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1317         flush_thread();
1318         me->personality &= ~bprm->per_clear;
1319
1320         clear_syscall_work_syscall_user_dispatch(me);
1321
1322         /*
1323          * We have to apply CLOEXEC before we change whether the process is
1324          * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1325          * trying to access the should-be-closed file descriptors of a process
1326          * undergoing exec(2).
1327          */
1328         do_close_on_exec(me->files);
1329
1330         if (bprm->secureexec) {
1331                 /* Make sure parent cannot signal privileged process. */
1332                 me->pdeath_signal = 0;
1333
1334                 /*
1335                  * For secureexec, reset the stack limit to sane default to
1336                  * avoid bad behavior from the prior rlimits. This has to
1337                  * happen before arch_pick_mmap_layout(), which examines
1338                  * RLIMIT_STACK, but after the point of no return to avoid
1339                  * needing to clean up the change on failure.
1340                  */
1341                 if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1342                         bprm->rlim_stack.rlim_cur = _STK_LIM;
1343         }
1344
1345         me->sas_ss_sp = me->sas_ss_size = 0;
1346
1347         /*
1348          * Figure out dumpability. Note that this checking only of current
1349          * is wrong, but userspace depends on it. This should be testing
1350          * bprm->secureexec instead.
1351          */
1352         if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1353             !(uid_eq(current_euid(), current_uid()) &&
1354               gid_eq(current_egid(), current_gid())))
1355                 set_dumpable(current->mm, suid_dumpable);
1356         else
1357                 set_dumpable(current->mm, SUID_DUMP_USER);
1358
1359         perf_event_exec();
1360         __set_task_comm(me, kbasename(bprm->filename), true);
1361
1362         /* An exec changes our domain. We are no longer part of the thread
1363            group */
1364         WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1365         flush_signal_handlers(me, 0);
1366
1367         retval = set_cred_ucounts(bprm->cred);
1368         if (retval < 0)
1369                 goto out_unlock;
1370
1371         /*
1372          * install the new credentials for this executable
1373          */
1374         security_bprm_committing_creds(bprm);
1375
1376         commit_creds(bprm->cred);
1377         bprm->cred = NULL;
1378
1379         /*
1380          * Disable monitoring for regular users
1381          * when executing setuid binaries. Must
1382          * wait until new credentials are committed
1383          * by commit_creds() above
1384          */
1385         if (get_dumpable(me->mm) != SUID_DUMP_USER)
1386                 perf_event_exit_task(me);
1387         /*
1388          * cred_guard_mutex must be held at least to this point to prevent
1389          * ptrace_attach() from altering our determination of the task's
1390          * credentials; any time after this it may be unlocked.
1391          */
1392         security_bprm_committed_creds(bprm);
1393
1394         /* Pass the opened binary to the interpreter. */
1395         if (bprm->have_execfd) {
1396                 retval = get_unused_fd_flags(0);
1397                 if (retval < 0)
1398                         goto out_unlock;
1399                 fd_install(retval, bprm->executable);
1400                 bprm->executable = NULL;
1401                 bprm->execfd = retval;
1402         }
1403         return 0;
1404
1405 out_unlock:
1406         up_write(&me->signal->exec_update_lock);
1407 out:
1408         return retval;
1409 }
1410 EXPORT_SYMBOL(begin_new_exec);
1411
1412 void would_dump(struct linux_binprm *bprm, struct file *file)
1413 {
1414         struct inode *inode = file_inode(file);
1415         struct user_namespace *mnt_userns = file_mnt_user_ns(file);
1416         if (inode_permission(mnt_userns, inode, MAY_READ) < 0) {
1417                 struct user_namespace *old, *user_ns;
1418                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1419
1420                 /* Ensure mm->user_ns contains the executable */
1421                 user_ns = old = bprm->mm->user_ns;
1422                 while ((user_ns != &init_user_ns) &&
1423                        !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode))
1424                         user_ns = user_ns->parent;
1425
1426                 if (old != user_ns) {
1427                         bprm->mm->user_ns = get_user_ns(user_ns);
1428                         put_user_ns(old);
1429                 }
1430         }
1431 }
1432 EXPORT_SYMBOL(would_dump);
1433
1434 void setup_new_exec(struct linux_binprm * bprm)
1435 {
1436         /* Setup things that can depend upon the personality */
1437         struct task_struct *me = current;
1438
1439         arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1440
1441         arch_setup_new_exec();
1442
1443         /* Set the new mm task size. We have to do that late because it may
1444          * depend on TIF_32BIT which is only updated in flush_thread() on
1445          * some architectures like powerpc
1446          */
1447         me->mm->task_size = TASK_SIZE;
1448         up_write(&me->signal->exec_update_lock);
1449         mutex_unlock(&me->signal->cred_guard_mutex);
1450 }
1451 EXPORT_SYMBOL(setup_new_exec);
1452
1453 /* Runs immediately before start_thread() takes over. */
1454 void finalize_exec(struct linux_binprm *bprm)
1455 {
1456         /* Store any stack rlimit changes before starting thread. */
1457         task_lock(current->group_leader);
1458         current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1459         task_unlock(current->group_leader);
1460 }
1461 EXPORT_SYMBOL(finalize_exec);
1462
1463 /*
1464  * Prepare credentials and lock ->cred_guard_mutex.
1465  * setup_new_exec() commits the new creds and drops the lock.
1466  * Or, if exec fails before, free_bprm() should release ->cred
1467  * and unlock.
1468  */
1469 static int prepare_bprm_creds(struct linux_binprm *bprm)
1470 {
1471         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1472                 return -ERESTARTNOINTR;
1473
1474         bprm->cred = prepare_exec_creds();
1475         if (likely(bprm->cred))
1476                 return 0;
1477
1478         mutex_unlock(&current->signal->cred_guard_mutex);
1479         return -ENOMEM;
1480 }
1481
1482 static void free_bprm(struct linux_binprm *bprm)
1483 {
1484         if (bprm->mm) {
1485                 acct_arg_size(bprm, 0);
1486                 mmput(bprm->mm);
1487         }
1488         free_arg_pages(bprm);
1489         if (bprm->cred) {
1490                 mutex_unlock(&current->signal->cred_guard_mutex);
1491                 abort_creds(bprm->cred);
1492         }
1493         if (bprm->file) {
1494                 allow_write_access(bprm->file);
1495                 fput(bprm->file);
1496         }
1497         if (bprm->executable)
1498                 fput(bprm->executable);
1499         /* If a binfmt changed the interp, free it. */
1500         if (bprm->interp != bprm->filename)
1501                 kfree(bprm->interp);
1502         kfree(bprm->fdpath);
1503         kfree(bprm);
1504 }
1505
1506 static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1507 {
1508         struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1509         int retval = -ENOMEM;
1510         if (!bprm)
1511                 goto out;
1512
1513         if (fd == AT_FDCWD || filename->name[0] == '/') {
1514                 bprm->filename = filename->name;
1515         } else {
1516                 if (filename->name[0] == '\0')
1517                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1518                 else
1519                         bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1520                                                   fd, filename->name);
1521                 if (!bprm->fdpath)
1522                         goto out_free;
1523
1524                 bprm->filename = bprm->fdpath;
1525         }
1526         bprm->interp = bprm->filename;
1527
1528         retval = bprm_mm_init(bprm);
1529         if (retval)
1530                 goto out_free;
1531         return bprm;
1532
1533 out_free:
1534         free_bprm(bprm);
1535 out:
1536         return ERR_PTR(retval);
1537 }
1538
1539 int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1540 {
1541         /* If a binfmt changed the interp, free it first. */
1542         if (bprm->interp != bprm->filename)
1543                 kfree(bprm->interp);
1544         bprm->interp = kstrdup(interp, GFP_KERNEL);
1545         if (!bprm->interp)
1546                 return -ENOMEM;
1547         return 0;
1548 }
1549 EXPORT_SYMBOL(bprm_change_interp);
1550
1551 /*
1552  * determine how safe it is to execute the proposed program
1553  * - the caller must hold ->cred_guard_mutex to protect against
1554  *   PTRACE_ATTACH or seccomp thread-sync
1555  */
1556 static void check_unsafe_exec(struct linux_binprm *bprm)
1557 {
1558         struct task_struct *p = current, *t;
1559         unsigned n_fs;
1560
1561         if (p->ptrace)
1562                 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1563
1564         /*
1565          * This isn't strictly necessary, but it makes it harder for LSMs to
1566          * mess up.
1567          */
1568         if (task_no_new_privs(current))
1569                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1570
1571         t = p;
1572         n_fs = 1;
1573         spin_lock(&p->fs->lock);
1574         rcu_read_lock();
1575         while_each_thread(p, t) {
1576                 if (t->fs == p->fs)
1577                         n_fs++;
1578         }
1579         rcu_read_unlock();
1580
1581         if (p->fs->users > n_fs)
1582                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1583         else
1584                 p->fs->in_exec = 1;
1585         spin_unlock(&p->fs->lock);
1586 }
1587
1588 static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1589 {
1590         /* Handle suid and sgid on files */
1591         struct user_namespace *mnt_userns;
1592         struct inode *inode;
1593         unsigned int mode;
1594         kuid_t uid;
1595         kgid_t gid;
1596
1597         if (!mnt_may_suid(file->f_path.mnt))
1598                 return;
1599
1600         if (task_no_new_privs(current))
1601                 return;
1602
1603         inode = file->f_path.dentry->d_inode;
1604         mode = READ_ONCE(inode->i_mode);
1605         if (!(mode & (S_ISUID|S_ISGID)))
1606                 return;
1607
1608         mnt_userns = file_mnt_user_ns(file);
1609
1610         /* Be careful if suid/sgid is set */
1611         inode_lock(inode);
1612
1613         /* reload atomically mode/uid/gid now that lock held */
1614         mode = inode->i_mode;
1615         uid = i_uid_into_mnt(mnt_userns, inode);
1616         gid = i_gid_into_mnt(mnt_userns, inode);
1617         inode_unlock(inode);
1618
1619         /* We ignore suid/sgid if there are no mappings for them in the ns */
1620         if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1621                  !kgid_has_mapping(bprm->cred->user_ns, gid))
1622                 return;
1623
1624         if (mode & S_ISUID) {
1625                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1626                 bprm->cred->euid = uid;
1627         }
1628
1629         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1630                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1631                 bprm->cred->egid = gid;
1632         }
1633 }
1634
1635 /*
1636  * Compute brpm->cred based upon the final binary.
1637  */
1638 static int bprm_creds_from_file(struct linux_binprm *bprm)
1639 {
1640         /* Compute creds based on which file? */
1641         struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1642
1643         bprm_fill_uid(bprm, file);
1644         return security_bprm_creds_from_file(bprm, file);
1645 }
1646
1647 /*
1648  * Fill the binprm structure from the inode.
1649  * Read the first BINPRM_BUF_SIZE bytes
1650  *
1651  * This may be called multiple times for binary chains (scripts for example).
1652  */
1653 static int prepare_binprm(struct linux_binprm *bprm)
1654 {
1655         loff_t pos = 0;
1656
1657         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1658         return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1659 }
1660
1661 /*
1662  * Arguments are '\0' separated strings found at the location bprm->p
1663  * points to; chop off the first by relocating brpm->p to right after
1664  * the first '\0' encountered.
1665  */
1666 int remove_arg_zero(struct linux_binprm *bprm)
1667 {
1668         int ret = 0;
1669         unsigned long offset;
1670         char *kaddr;
1671         struct page *page;
1672
1673         if (!bprm->argc)
1674                 return 0;
1675
1676         do {
1677                 offset = bprm->p & ~PAGE_MASK;
1678                 page = get_arg_page(bprm, bprm->p, 0);
1679                 if (!page) {
1680                         ret = -EFAULT;
1681                         goto out;
1682                 }
1683                 kaddr = kmap_atomic(page);
1684
1685                 for (; offset < PAGE_SIZE && kaddr[offset];
1686                                 offset++, bprm->p++)
1687                         ;
1688
1689                 kunmap_atomic(kaddr);
1690                 put_arg_page(page);
1691         } while (offset == PAGE_SIZE);
1692
1693         bprm->p++;
1694         bprm->argc--;
1695         ret = 0;
1696
1697 out:
1698         return ret;
1699 }
1700 EXPORT_SYMBOL(remove_arg_zero);
1701
1702 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1703 /*
1704  * cycle the list of binary formats handler, until one recognizes the image
1705  */
1706 static int search_binary_handler(struct linux_binprm *bprm)
1707 {
1708         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1709         struct linux_binfmt *fmt;
1710         int retval;
1711
1712         retval = prepare_binprm(bprm);
1713         if (retval < 0)
1714                 return retval;
1715
1716         retval = security_bprm_check(bprm);
1717         if (retval)
1718                 return retval;
1719
1720         retval = -ENOENT;
1721  retry:
1722         read_lock(&binfmt_lock);
1723         list_for_each_entry(fmt, &formats, lh) {
1724                 if (!try_module_get(fmt->module))
1725                         continue;
1726                 read_unlock(&binfmt_lock);
1727
1728                 retval = fmt->load_binary(bprm);
1729
1730                 read_lock(&binfmt_lock);
1731                 put_binfmt(fmt);
1732                 if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1733                         read_unlock(&binfmt_lock);
1734                         return retval;
1735                 }
1736         }
1737         read_unlock(&binfmt_lock);
1738
1739         if (need_retry) {
1740                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1741                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1742                         return retval;
1743                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1744                         return retval;
1745                 need_retry = false;
1746                 goto retry;
1747         }
1748
1749         return retval;
1750 }
1751
1752 static int exec_binprm(struct linux_binprm *bprm)
1753 {
1754         pid_t old_pid, old_vpid;
1755         int ret, depth;
1756
1757         /* Need to fetch pid before load_binary changes it */
1758         old_pid = current->pid;
1759         rcu_read_lock();
1760         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1761         rcu_read_unlock();
1762
1763         /* This allows 4 levels of binfmt rewrites before failing hard. */
1764         for (depth = 0;; depth++) {
1765                 struct file *exec;
1766                 if (depth > 5)
1767                         return -ELOOP;
1768
1769                 ret = search_binary_handler(bprm);
1770                 if (ret < 0)
1771                         return ret;
1772                 if (!bprm->interpreter)
1773                         break;
1774
1775                 exec = bprm->file;
1776                 bprm->file = bprm->interpreter;
1777                 bprm->interpreter = NULL;
1778
1779                 allow_write_access(exec);
1780                 if (unlikely(bprm->have_execfd)) {
1781                         if (bprm->executable) {
1782                                 fput(exec);
1783                                 return -ENOEXEC;
1784                         }
1785                         bprm->executable = exec;
1786                 } else
1787                         fput(exec);
1788         }
1789
1790         audit_bprm(bprm);
1791         trace_sched_process_exec(current, old_pid, bprm);
1792         ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1793         proc_exec_connector(current);
1794         return 0;
1795 }
1796
1797 /*
1798  * sys_execve() executes a new program.
1799  */
1800 static int bprm_execve(struct linux_binprm *bprm,
1801                        int fd, struct filename *filename, int flags)
1802 {
1803         struct file *file;
1804         int retval;
1805
1806         retval = prepare_bprm_creds(bprm);
1807         if (retval)
1808                 return retval;
1809
1810         check_unsafe_exec(bprm);
1811         current->in_execve = 1;
1812
1813         file = do_open_execat(fd, filename, flags);
1814         retval = PTR_ERR(file);
1815         if (IS_ERR(file))
1816                 goto out_unmark;
1817
1818         sched_exec();
1819
1820         bprm->file = file;
1821         /*
1822          * Record that a name derived from an O_CLOEXEC fd will be
1823          * inaccessible after exec.  This allows the code in exec to
1824          * choose to fail when the executable is not mmaped into the
1825          * interpreter and an open file descriptor is not passed to
1826          * the interpreter.  This makes for a better user experience
1827          * than having the interpreter start and then immediately fail
1828          * when it finds the executable is inaccessible.
1829          */
1830         if (bprm->fdpath && get_close_on_exec(fd))
1831                 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1832
1833         /* Set the unchanging part of bprm->cred */
1834         retval = security_bprm_creds_for_exec(bprm);
1835         if (retval)
1836                 goto out;
1837
1838         retval = exec_binprm(bprm);
1839         if (retval < 0)
1840                 goto out;
1841
1842         /* execve succeeded */
1843         current->fs->in_exec = 0;
1844         current->in_execve = 0;
1845         rseq_execve(current);
1846         acct_update_integrals(current);
1847         task_numa_free(current, false);
1848         return retval;
1849
1850 out:
1851         /*
1852          * If past the point of no return ensure the code never
1853          * returns to the userspace process.  Use an existing fatal
1854          * signal if present otherwise terminate the process with
1855          * SIGSEGV.
1856          */
1857         if (bprm->point_of_no_return && !fatal_signal_pending(current))
1858                 force_fatal_sig(SIGSEGV);
1859
1860 out_unmark:
1861         current->fs->in_exec = 0;
1862         current->in_execve = 0;
1863
1864         return retval;
1865 }
1866
1867 static int do_execveat_common(int fd, struct filename *filename,
1868                               struct user_arg_ptr argv,
1869                               struct user_arg_ptr envp,
1870                               int flags)
1871 {
1872         struct linux_binprm *bprm;
1873         int retval;
1874
1875         if (IS_ERR(filename))
1876                 return PTR_ERR(filename);
1877
1878         /*
1879          * We move the actual failure in case of RLIMIT_NPROC excess from
1880          * set*uid() to execve() because too many poorly written programs
1881          * don't check setuid() return code.  Here we additionally recheck
1882          * whether NPROC limit is still exceeded.
1883          */
1884         if ((current->flags & PF_NPROC_EXCEEDED) &&
1885             is_ucounts_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1886                 retval = -EAGAIN;
1887                 goto out_ret;
1888         }
1889
1890         /* We're below the limit (still or again), so we don't want to make
1891          * further execve() calls fail. */
1892         current->flags &= ~PF_NPROC_EXCEEDED;
1893
1894         bprm = alloc_bprm(fd, filename);
1895         if (IS_ERR(bprm)) {
1896                 retval = PTR_ERR(bprm);
1897                 goto out_ret;
1898         }
1899
1900         retval = count(argv, MAX_ARG_STRINGS);
1901         if (retval == 0)
1902                 pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1903                              current->comm, bprm->filename);
1904         if (retval < 0)
1905                 goto out_free;
1906         bprm->argc = retval;
1907
1908         retval = count(envp, MAX_ARG_STRINGS);
1909         if (retval < 0)
1910                 goto out_free;
1911         bprm->envc = retval;
1912
1913         retval = bprm_stack_limits(bprm);
1914         if (retval < 0)
1915                 goto out_free;
1916
1917         retval = copy_string_kernel(bprm->filename, bprm);
1918         if (retval < 0)
1919                 goto out_free;
1920         bprm->exec = bprm->p;
1921
1922         retval = copy_strings(bprm->envc, envp, bprm);
1923         if (retval < 0)
1924                 goto out_free;
1925
1926         retval = copy_strings(bprm->argc, argv, bprm);
1927         if (retval < 0)
1928                 goto out_free;
1929
1930         /*
1931          * When argv is empty, add an empty string ("") as argv[0] to
1932          * ensure confused userspace programs that start processing
1933          * from argv[1] won't end up walking envp. See also
1934          * bprm_stack_limits().
1935          */
1936         if (bprm->argc == 0) {
1937                 retval = copy_string_kernel("", bprm);
1938                 if (retval < 0)
1939                         goto out_free;
1940                 bprm->argc = 1;
1941         }
1942
1943         retval = bprm_execve(bprm, fd, filename, flags);
1944 out_free:
1945         free_bprm(bprm);
1946
1947 out_ret:
1948         putname(filename);
1949         return retval;
1950 }
1951
1952 int kernel_execve(const char *kernel_filename,
1953                   const char *const *argv, const char *const *envp)
1954 {
1955         struct filename *filename;
1956         struct linux_binprm *bprm;
1957         int fd = AT_FDCWD;
1958         int retval;
1959
1960         /* It is non-sense for kernel threads to call execve */
1961         if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1962                 return -EINVAL;
1963
1964         filename = getname_kernel(kernel_filename);
1965         if (IS_ERR(filename))
1966                 return PTR_ERR(filename);
1967
1968         bprm = alloc_bprm(fd, filename);
1969         if (IS_ERR(bprm)) {
1970                 retval = PTR_ERR(bprm);
1971                 goto out_ret;
1972         }
1973
1974         retval = count_strings_kernel(argv);
1975         if (WARN_ON_ONCE(retval == 0))
1976                 retval = -EINVAL;
1977         if (retval < 0)
1978                 goto out_free;
1979         bprm->argc = retval;
1980
1981         retval = count_strings_kernel(envp);
1982         if (retval < 0)
1983                 goto out_free;
1984         bprm->envc = retval;
1985
1986         retval = bprm_stack_limits(bprm);
1987         if (retval < 0)
1988                 goto out_free;
1989
1990         retval = copy_string_kernel(bprm->filename, bprm);
1991         if (retval < 0)
1992                 goto out_free;
1993         bprm->exec = bprm->p;
1994
1995         retval = copy_strings_kernel(bprm->envc, envp, bprm);
1996         if (retval < 0)
1997                 goto out_free;
1998
1999         retval = copy_strings_kernel(bprm->argc, argv, bprm);
2000         if (retval < 0)
2001                 goto out_free;
2002
2003         retval = bprm_execve(bprm, fd, filename, 0);
2004 out_free:
2005         free_bprm(bprm);
2006 out_ret:
2007         putname(filename);
2008         return retval;
2009 }
2010
2011 static int do_execve(struct filename *filename,
2012         const char __user *const __user *__argv,
2013         const char __user *const __user *__envp)
2014 {
2015         struct user_arg_ptr argv = { .ptr.native = __argv };
2016         struct user_arg_ptr envp = { .ptr.native = __envp };
2017         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2018 }
2019
2020 static int do_execveat(int fd, struct filename *filename,
2021                 const char __user *const __user *__argv,
2022                 const char __user *const __user *__envp,
2023                 int flags)
2024 {
2025         struct user_arg_ptr argv = { .ptr.native = __argv };
2026         struct user_arg_ptr envp = { .ptr.native = __envp };
2027
2028         return do_execveat_common(fd, filename, argv, envp, flags);
2029 }
2030
2031 #ifdef CONFIG_COMPAT
2032 static int compat_do_execve(struct filename *filename,
2033         const compat_uptr_t __user *__argv,
2034         const compat_uptr_t __user *__envp)
2035 {
2036         struct user_arg_ptr argv = {
2037                 .is_compat = true,
2038                 .ptr.compat = __argv,
2039         };
2040         struct user_arg_ptr envp = {
2041                 .is_compat = true,
2042                 .ptr.compat = __envp,
2043         };
2044         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2045 }
2046
2047 static int compat_do_execveat(int fd, struct filename *filename,
2048                               const compat_uptr_t __user *__argv,
2049                               const compat_uptr_t __user *__envp,
2050                               int flags)
2051 {
2052         struct user_arg_ptr argv = {
2053                 .is_compat = true,
2054                 .ptr.compat = __argv,
2055         };
2056         struct user_arg_ptr envp = {
2057                 .is_compat = true,
2058                 .ptr.compat = __envp,
2059         };
2060         return do_execveat_common(fd, filename, argv, envp, flags);
2061 }
2062 #endif
2063
2064 void set_binfmt(struct linux_binfmt *new)
2065 {
2066         struct mm_struct *mm = current->mm;
2067
2068         if (mm->binfmt)
2069                 module_put(mm->binfmt->module);
2070
2071         mm->binfmt = new;
2072         if (new)
2073                 __module_get(new->module);
2074 }
2075 EXPORT_SYMBOL(set_binfmt);
2076
2077 /*
2078  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2079  */
2080 void set_dumpable(struct mm_struct *mm, int value)
2081 {
2082         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2083                 return;
2084
2085         set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2086 }
2087
2088 SYSCALL_DEFINE3(execve,
2089                 const char __user *, filename,
2090                 const char __user *const __user *, argv,
2091                 const char __user *const __user *, envp)
2092 {
2093         return do_execve(getname(filename), argv, envp);
2094 }
2095
2096 SYSCALL_DEFINE5(execveat,
2097                 int, fd, const char __user *, filename,
2098                 const char __user *const __user *, argv,
2099                 const char __user *const __user *, envp,
2100                 int, flags)
2101 {
2102         return do_execveat(fd,
2103                            getname_uflags(filename, flags),
2104                            argv, envp, flags);
2105 }
2106
2107 #ifdef CONFIG_COMPAT
2108 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2109         const compat_uptr_t __user *, argv,
2110         const compat_uptr_t __user *, envp)
2111 {
2112         return compat_do_execve(getname(filename), argv, envp);
2113 }
2114
2115 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2116                        const char __user *, filename,
2117                        const compat_uptr_t __user *, argv,
2118                        const compat_uptr_t __user *, envp,
2119                        int,  flags)
2120 {
2121         return compat_do_execveat(fd,
2122                                   getname_uflags(filename, flags),
2123                                   argv, envp, flags);
2124 }
2125 #endif
2126
2127 #ifdef CONFIG_SYSCTL
2128
2129 static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2130                 void *buffer, size_t *lenp, loff_t *ppos)
2131 {
2132         int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2133
2134         if (!error)
2135                 validate_coredump_safety();
2136         return error;
2137 }
2138
2139 static struct ctl_table fs_exec_sysctls[] = {
2140         {
2141                 .procname       = "suid_dumpable",
2142                 .data           = &suid_dumpable,
2143                 .maxlen         = sizeof(int),
2144                 .mode           = 0644,
2145                 .proc_handler   = proc_dointvec_minmax_coredump,
2146                 .extra1         = SYSCTL_ZERO,
2147                 .extra2         = SYSCTL_TWO,
2148         },
2149         { }
2150 };
2151
2152 static int __init init_fs_exec_sysctls(void)
2153 {
2154         register_sysctl_init("fs", fs_exec_sysctls);
2155         return 0;
2156 }
2157
2158 fs_initcall(init_fs_exec_sysctls);
2159 #endif /* CONFIG_SYSCTL */