fs/exec.c

   1 /*
   2  *  linux/fs/exec.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * #!-checking implemented by tytso.
   9  */
  10 /*
  11  * Demand-loading implemented 01.12.91 - no need to read anything but
  12  * the header into memory. The inode of the executable is put into
  13  * "current->executable", and page faults do the actual loading. Clean.
  14  *
  15  * Once more I can proudly say that linux stood up to being changed: it
  16  * was less than 2 hours work to get demand-loading completely implemented.
  17  *
  18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
  19  * current->executable is only used by the procfs.  This allows a dispatch
  20  * table to check for several different types  of binary formats.  We keep
  21  * trying until we recognize the file or we run out of supported binary
  22  * formats.
  23  */
  24
  25 #include <linux/slab.h>
  26 #include <linux/file.h>
  27 #include <linux/fdtable.h>
  28 #include <linux/mm.h>
  29 #include <linux/vmacache.h>
  30 #include <linux/stat.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/swap.h>
  33 #include <linux/string.h>
  34 #include <linux/init.h>
  35 #include <linux/pagemap.h>
  36 #include <linux/perf_event.h>
  37 #include <linux/highmem.h>
  38 #include <linux/spinlock.h>
  39 #include <linux/key.h>
  40 #include <linux/personality.h>
  41 #include <linux/binfmts.h>
  42 #include <linux/utsname.h>
  43 #include <linux/pid_namespace.h>
  44 #include <linux/module.h>
  45 #include <linux/namei.h>
  46 #include <linux/mount.h>
  47 #include <linux/security.h>
  48 #include <linux/syscalls.h>
  49 #include <linux/tsacct_kern.h>
  50 #include <linux/cn_proc.h>
  51 #include <linux/audit.h>
  52 #include <linux/tracehook.h>
  53 #include <linux/kmod.h>
  54 #include <linux/fsnotify.h>
  55 #include <linux/fs_struct.h>
  56 #include <linux/pipe_fs_i.h>
  57 #include <linux/oom.h>
  58 #include <linux/compat.h>
  59
  60 #include <asm/uaccess.h>
  61 #include <asm/mmu_context.h>
  62 #include <asm/tlb.h>
  63
  64 #include <trace/events/task.h>
  65 #include "internal.h"
  66
  67 #include <trace/events/sched.h>
  68
  69 int suid_dumpable = 0;
  70
  71 static LIST_HEAD(formats);
  72 static DEFINE_RWLOCK(binfmt_lock);
  73
  74 void __register_binfmt(struct linux_binfmt * fmt, int insert)
  75 {
  76         BUG_ON(!fmt);
  77         if (WARN_ON(!fmt->load_binary))
  78                 return;
  79         write_lock(&binfmt_lock);
  80         insert ? list_add(&fmt->lh, &formats) :
  81                  list_add_tail(&fmt->lh, &formats);
  82         write_unlock(&binfmt_lock);
  83 }
  84
  85 EXPORT_SYMBOL(__register_binfmt);
  86
  87 void unregister_binfmt(struct linux_binfmt * fmt)
  88 {
  89         write_lock(&binfmt_lock);
  90         list_del(&fmt->lh);
  91         write_unlock(&binfmt_lock);
  92 }
  93
  94 EXPORT_SYMBOL(unregister_binfmt);
  95
  96 static inline void put_binfmt(struct linux_binfmt * fmt)
  97 {
  98         module_put(fmt->module);
  99 }
 100
 101 #ifdef CONFIG_USELIB
 102 /*
 103  * Note that a shared library must be both readable and executable due to
 104  * security reasons.
 105  *
 106  * Also note that we take the address to load from from the file itself.
 107  */
 108 SYSCALL_DEFINE1(uselib, const char __user *, library)
 109 {
 110         struct linux_binfmt *fmt;
 111         struct file *file;
 112         struct filename *tmp = getname(library);
 113         int error = PTR_ERR(tmp);
 114         static const struct open_flags uselib_flags = {
 115                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 116                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
 117                 .intent = LOOKUP_OPEN,
 118                 .lookup_flags = LOOKUP_FOLLOW,
 119         };
 120
 121         if (IS_ERR(tmp))
 122                 goto out;
 123
 124         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
 125         putname(tmp);
 126         error = PTR_ERR(file);
 127         if (IS_ERR(file))
 128                 goto out;
 129
 130         error = -EINVAL;
 131         if (!S_ISREG(file_inode(file)->i_mode))
 132                 goto exit;
 133
 134         error = -EACCES;
 135         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 136                 goto exit;
 137
 138         fsnotify_open(file);
 139
 140         error = -ENOEXEC;
 141
 142         read_lock(&binfmt_lock);
 143         list_for_each_entry(fmt, &formats, lh) {
 144                 if (!fmt->load_shlib)
 145                         continue;
 146                 if (!try_module_get(fmt->module))
 147                         continue;
 148                 read_unlock(&binfmt_lock);
 149                 error = fmt->load_shlib(file);
 150                 read_lock(&binfmt_lock);
 151                 put_binfmt(fmt);
 152                 if (error != -ENOEXEC)
 153                         break;
 154         }
 155         read_unlock(&binfmt_lock);
 156 exit:
 157         fput(file);
 158 out:
 159         return error;
 160 }
 161 #endif /* #ifdef CONFIG_USELIB */
 162
 163 #ifdef CONFIG_MMU
 164 /*
 165  * The nascent bprm->mm is not visible until exec_mmap() but it can
 166  * use a lot of memory, account these pages in current->mm temporary
 167  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 168  * change the counter back via acct_arg_size(0).
 169  */
 170 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
 171 {
 172         struct mm_struct *mm = current->mm;
 173         long diff = (long)(pages - bprm->vma_pages);
 174
 175         if (!mm || !diff)
 176                 return;
 177
 178         bprm->vma_pages = pages;
 179         add_mm_counter(mm, MM_ANONPAGES, diff);
 180 }
 181
 182 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 183                 int write)
 184 {
 185         struct page *page;
 186         int ret;
 187
 188 #ifdef CONFIG_STACK_GROWSUP
 189         if (write) {
 190                 ret = expand_downwards(bprm->vma, pos);
 191                 if (ret < 0)
 192                         return NULL;
 193         }
 194 #endif
 195         ret = get_user_pages(current, bprm->mm, pos,
 196                         1, write, 1, &page, NULL);
 197         if (ret <= 0)
 198                 return NULL;
 199
 200         if (write) {
 201                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
 202                 struct rlimit *rlim;
 203
 204                 acct_arg_size(bprm, size / PAGE_SIZE);
 205
 206                 /*
 207                  * We've historically supported up to 32 pages (ARG_MAX)
 208                  * of argument strings even with small stacks
 209                  */
 210                 if (size <= ARG_MAX)
 211                         return page;
 212
 213                 /*
 214                  * Limit to 1/4-th the stack size for the argv+env strings.
 215                  * This ensures that:
 216                  *  - the remaining binfmt code will not run out of stack space,
 217                  *  - the program will have a reasonable amount of stack left
 218                  *    to work from.
 219                  */
 220                 rlim = current->signal->rlim;
 221                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
 222                         put_page(page);
 223                         return NULL;
 224                 }
 225         }
 226
 227         return page;
 228 }
 229
 230 static void put_arg_page(struct page *page)
 231 {
 232         put_page(page);
 233 }
 234
 235 static void free_arg_page(struct linux_binprm *bprm, int i)
 236 {
 237 }
 238
 239 static void free_arg_pages(struct linux_binprm *bprm)
 240 {
 241 }
 242
 243 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
 244                 struct page *page)
 245 {
 246         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
 247 }
 248
 249 static int __bprm_mm_init(struct linux_binprm *bprm)
 250 {
 251         int err;
 252         struct vm_area_struct *vma = NULL;
 253         struct mm_struct *mm = bprm->mm;
 254
 255         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
 256         if (!vma)
 257                 return -ENOMEM;
 258
 259         down_write(&mm->mmap_sem);
 260         vma->vm_mm = mm;
 261
 262         /*
 263          * Place the stack at the largest stack address the architecture
 264          * supports. Later, we'll move this to an appropriate place. We don't
 265          * use STACK_TOP because that can depend on attributes which aren't
 266          * configured yet.
 267          */
 268         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 269         vma->vm_end = STACK_TOP_MAX;
 270         vma->vm_start = vma->vm_end - PAGE_SIZE;
 271         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 272         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 273         INIT_LIST_HEAD(&vma->anon_vma_chain);
 274
 275         err = insert_vm_struct(mm, vma);
 276         if (err)
 277                 goto err;
 278
 279         mm->stack_vm = mm->total_vm = 1;
 280         arch_bprm_mm_init(mm, vma);
 281         up_write(&mm->mmap_sem);
 282         bprm->p = vma->vm_end - sizeof(void *);
 283         return 0;
 284 err:
 285         up_write(&mm->mmap_sem);
 286         bprm->vma = NULL;
 287         kmem_cache_free(vm_area_cachep, 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         err = __bprm_mm_init(bprm);
 373         if (err)
 374                 goto err;
 375
 376         return 0;
 377
 378 err:
 379         if (mm) {
 380                 bprm->mm = NULL;
 381                 mmdrop(mm);
 382         }
 383
 384         return err;
 385 }
 386
 387 struct user_arg_ptr {
 388 #ifdef CONFIG_COMPAT
 389         bool is_compat;
 390 #endif
 391         union {
 392                 const char __user *const __user *native;
 393 #ifdef CONFIG_COMPAT
 394                 const compat_uptr_t __user *compat;
 395 #endif
 396         } ptr;
 397 };
 398
 399 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
 400 {
 401         const char __user *native;
 402
 403 #ifdef CONFIG_COMPAT
 404         if (unlikely(argv.is_compat)) {
 405                 compat_uptr_t compat;
 406
 407                 if (get_user(compat, argv.ptr.compat + nr))
 408                         return ERR_PTR(-EFAULT);
 409
 410                 return compat_ptr(compat);
 411         }
 412 #endif
 413
 414         if (get_user(native, argv.ptr.native + nr))
 415                 return ERR_PTR(-EFAULT);
 416
 417         return native;
 418 }
 419
 420 /*
 421  * count() counts the number of strings in array ARGV.
 422  */
 423 static int count(struct user_arg_ptr argv, int max)
 424 {
 425         int i = 0;
 426
 427         if (argv.ptr.native != NULL) {
 428                 for (;;) {
 429                         const char __user *p = get_user_arg_ptr(argv, i);
 430
 431                         if (!p)
 432                                 break;
 433
 434                         if (IS_ERR(p))
 435                                 return -EFAULT;
 436
 437                         if (i >= max)
 438                                 return -E2BIG;
 439                         ++i;
 440
 441                         if (fatal_signal_pending(current))
 442                                 return -ERESTARTNOHAND;
 443                         cond_resched();
 444                 }
 445         }
 446         return i;
 447 }
 448
 449 /*
 450  * 'copy_strings()' copies argument/environment strings from the old
 451  * processes's memory to the new process's stack.  The call to get_user_pages()
 452  * ensures the destination page is created and not swapped out.
 453  */
 454 static int copy_strings(int argc, struct user_arg_ptr argv,
 455                         struct linux_binprm *bprm)
 456 {
 457         struct page *kmapped_page = NULL;
 458         char *kaddr = NULL;
 459         unsigned long kpos = 0;
 460         int ret;
 461
 462         while (argc-- > 0) {
 463                 const char __user *str;
 464                 int len;
 465                 unsigned long pos;
 466
 467                 ret = -EFAULT;
 468                 str = get_user_arg_ptr(argv, argc);
 469                 if (IS_ERR(str))
 470                         goto out;
 471
 472                 len = strnlen_user(str, MAX_ARG_STRLEN);
 473                 if (!len)
 474                         goto out;
 475
 476                 ret = -E2BIG;
 477                 if (!valid_arg_len(bprm, len))
 478                         goto out;
 479
 480                 /* We're going to work our way backwords. */
 481                 pos = bprm->p;
 482                 str += len;
 483                 bprm->p -= len;
 484
 485                 while (len > 0) {
 486                         int offset, bytes_to_copy;
 487
 488                         if (fatal_signal_pending(current)) {
 489                                 ret = -ERESTARTNOHAND;
 490                                 goto out;
 491                         }
 492                         cond_resched();
 493
 494                         offset = pos % PAGE_SIZE;
 495                         if (offset == 0)
 496                                 offset = PAGE_SIZE;
 497
 498                         bytes_to_copy = offset;
 499                         if (bytes_to_copy > len)
 500                                 bytes_to_copy = len;
 501
 502                         offset -= bytes_to_copy;
 503                         pos -= bytes_to_copy;
 504                         str -= bytes_to_copy;
 505                         len -= bytes_to_copy;
 506
 507                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
 508                                 struct page *page;
 509
 510                                 page = get_arg_page(bprm, pos, 1);
 511                                 if (!page) {
 512                                         ret = -E2BIG;
 513                                         goto out;
 514                                 }
 515
 516                                 if (kmapped_page) {
 517                                         flush_kernel_dcache_page(kmapped_page);
 518                                         kunmap(kmapped_page);
 519                                         put_arg_page(kmapped_page);
 520                                 }
 521                                 kmapped_page = page;
 522                                 kaddr = kmap(kmapped_page);
 523                                 kpos = pos & PAGE_MASK;
 524                                 flush_arg_page(bprm, kpos, kmapped_page);
 525                         }
 526                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
 527                                 ret = -EFAULT;
 528                                 goto out;
 529                         }
 530                 }
 531         }
 532         ret = 0;
 533 out:
 534         if (kmapped_page) {
 535                 flush_kernel_dcache_page(kmapped_page);
 536                 kunmap(kmapped_page);
 537                 put_arg_page(kmapped_page);
 538         }
 539         return ret;
 540 }
 541
 542 /*
 543  * Like copy_strings, but get argv and its values from kernel memory.
 544  */
 545 int copy_strings_kernel(int argc, const char *const *__argv,
 546                         struct linux_binprm *bprm)
 547 {
 548         int r;
 549         mm_segment_t oldfs = get_fs();
 550         struct user_arg_ptr argv = {
 551                 .ptr.native = (const char __user *const  __user *)__argv,
 552         };
 553
 554         set_fs(KERNEL_DS);
 555         r = copy_strings(argc, argv, bprm);
 556         set_fs(oldfs);
 557
 558         return r;
 559 }
 560 EXPORT_SYMBOL(copy_strings_kernel);
 561
 562 #ifdef CONFIG_MMU
 563
 564 /*
 565  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 566  * the binfmt code determines where the new stack should reside, we shift it to
 567  * its final location.  The process proceeds as follows:
 568  *
 569  * 1) Use shift to calculate the new vma endpoints.
 570  * 2) Extend vma to cover both the old and new ranges.  This ensures the
 571  *    arguments passed to subsequent functions are consistent.
 572  * 3) Move vma's page tables to the new range.
 573  * 4) Free up any cleared pgd range.
 574  * 5) Shrink the vma to cover only the new range.
 575  */
 576 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 577 {
 578         struct mm_struct *mm = vma->vm_mm;
 579         unsigned long old_start = vma->vm_start;
 580         unsigned long old_end = vma->vm_end;
 581         unsigned long length = old_end - old_start;
 582         unsigned long new_start = old_start - shift;
 583         unsigned long new_end = old_end - shift;
 584         struct mmu_gather tlb;
 585
 586         BUG_ON(new_start > new_end);
 587
 588         /*
 589          * ensure there are no vmas between where we want to go
 590          * and where we are
 591          */
 592         if (vma != find_vma(mm, new_start))
 593                 return -EFAULT;
 594
 595         /*
 596          * cover the whole range: [new_start, old_end)
 597          */
 598         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
 599                 return -ENOMEM;
 600
 601         /*
 602          * move the page tables downwards, on failure we rely on
 603          * process cleanup to remove whatever mess we made.
 604          */
 605         if (length != move_page_tables(vma, old_start,
 606                                        vma, new_start, length, false))
 607                 return -ENOMEM;
 608
 609         lru_add_drain();
 610         tlb_gather_mmu(&tlb, mm, old_start, old_end);
 611         if (new_end > old_start) {
 612                 /*
 613                  * when the old and new regions overlap clear from new_end.
 614                  */
 615                 free_pgd_range(&tlb, new_end, old_end, new_end,
 616                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 617         } else {
 618                 /*
 619                  * otherwise, clean from old_start; this is done to not touch
 620                  * the address space in [new_end, old_start) some architectures
 621                  * have constraints on va-space that make this illegal (IA64) -
 622                  * for the others its just a little faster.
 623                  */
 624                 free_pgd_range(&tlb, old_start, old_end, new_end,
 625                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
 626         }
 627         tlb_finish_mmu(&tlb, old_start, old_end);
 628
 629         /*
 630          * Shrink the vma to just the new range.  Always succeeds.
 631          */
 632         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
 633
 634         return 0;
 635 }
 636
 637 /*
 638  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 639  * the stack is optionally relocated, and some extra space is added.
 640  */
 641 int setup_arg_pages(struct linux_binprm *bprm,
 642                     unsigned long stack_top,
 643                     int executable_stack)
 644 {
 645         unsigned long ret;
 646         unsigned long stack_shift;
 647         struct mm_struct *mm = current->mm;
 648         struct vm_area_struct *vma = bprm->vma;
 649         struct vm_area_struct *prev = NULL;
 650         unsigned long vm_flags;
 651         unsigned long stack_base;
 652         unsigned long stack_size;
 653         unsigned long stack_expand;
 654         unsigned long rlim_stack;
 655
 656 #ifdef CONFIG_STACK_GROWSUP
 657         /* Limit stack size */
 658         stack_base = rlimit_max(RLIMIT_STACK);
 659         if (stack_base > STACK_SIZE_MAX)
 660                 stack_base = STACK_SIZE_MAX;
 661
 662         /* Make sure we didn't let the argument array grow too large. */
 663         if (vma->vm_end - vma->vm_start > stack_base)
 664                 return -ENOMEM;
 665
 666         stack_base = PAGE_ALIGN(stack_top - stack_base);
 667
 668         stack_shift = vma->vm_start - stack_base;
 669         mm->arg_start = bprm->p - stack_shift;
 670         bprm->p = vma->vm_end - stack_shift;
 671 #else
 672         stack_top = arch_align_stack(stack_top);
 673         stack_top = PAGE_ALIGN(stack_top);
 674
 675         if (unlikely(stack_top < mmap_min_addr) ||
 676             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
 677                 return -ENOMEM;
 678
 679         stack_shift = vma->vm_end - stack_top;
 680
 681         bprm->p -= stack_shift;
 682         mm->arg_start = bprm->p;
 683 #endif
 684
 685         if (bprm->loader)
 686                 bprm->loader -= stack_shift;
 687         bprm->exec -= stack_shift;
 688
 689         down_write(&mm->mmap_sem);
 690         vm_flags = VM_STACK_FLAGS;
 691
 692         /*
 693          * Adjust stack execute permissions; explicitly enable for
 694          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
 695          * (arch default) otherwise.
 696          */
 697         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
 698                 vm_flags |= VM_EXEC;
 699         else if (executable_stack == EXSTACK_DISABLE_X)
 700                 vm_flags &= ~VM_EXEC;
 701         vm_flags |= mm->def_flags;
 702         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 703
 704         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
 705                         vm_flags);
 706         if (ret)
 707                 goto out_unlock;
 708         BUG_ON(prev != vma);
 709
 710         /* Move stack pages down in memory. */
 711         if (stack_shift) {
 712                 ret = shift_arg_pages(vma, stack_shift);
 713                 if (ret)
 714                         goto out_unlock;
 715         }
 716
 717         /* mprotect_fixup is overkill to remove the temporary stack flags */
 718         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
 719
 720         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
 721         stack_size = vma->vm_end - vma->vm_start;
 722         /*
 723          * Align this down to a page boundary as expand_stack
 724          * will align it up.
 725          */
 726         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
 727 #ifdef CONFIG_STACK_GROWSUP
 728         if (stack_size + stack_expand > rlim_stack)
 729                 stack_base = vma->vm_start + rlim_stack;
 730         else
 731                 stack_base = vma->vm_end + stack_expand;
 732 #else
 733         if (stack_size + stack_expand > rlim_stack)
 734                 stack_base = vma->vm_end - rlim_stack;
 735         else
 736                 stack_base = vma->vm_start - stack_expand;
 737 #endif
 738         current->mm->start_stack = bprm->p;
 739         ret = expand_stack(vma, stack_base);
 740         if (ret)
 741                 ret = -EFAULT;
 742
 743 out_unlock:
 744         up_write(&mm->mmap_sem);
 745         return ret;
 746 }
 747 EXPORT_SYMBOL(setup_arg_pages);
 748
 749 #endif /* CONFIG_MMU */
 750
 751 static struct file *do_open_execat(int fd, struct filename *name, int flags)
 752 {
 753         struct file *file;
 754         int err;
 755         struct open_flags open_exec_flags = {
 756                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
 757                 .acc_mode = MAY_EXEC | MAY_OPEN,
 758                 .intent = LOOKUP_OPEN,
 759                 .lookup_flags = LOOKUP_FOLLOW,
 760         };
 761
 762         if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
 763                 return ERR_PTR(-EINVAL);
 764         if (flags & AT_SYMLINK_NOFOLLOW)
 765                 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
 766         if (flags & AT_EMPTY_PATH)
 767                 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
 768
 769         file = do_filp_open(fd, name, &open_exec_flags);
 770         if (IS_ERR(file))
 771                 goto out;
 772
 773         err = -EACCES;
 774         if (!S_ISREG(file_inode(file)->i_mode))
 775                 goto exit;
 776
 777         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
 778                 goto exit;
 779
 780         err = deny_write_access(file);
 781         if (err)
 782                 goto exit;
 783
 784         if (name->name[0] != '\0')
 785                 fsnotify_open(file);
 786
 787 out:
 788         return file;
 789
 790 exit:
 791         fput(file);
 792         return ERR_PTR(err);
 793 }
 794
 795 struct file *open_exec(const char *name)
 796 {
 797         struct filename tmp = { .name = name };
 798         return do_open_execat(AT_FDCWD, &tmp, 0);
 799 }
 800 EXPORT_SYMBOL(open_exec);
 801
 802 int kernel_read(struct file *file, loff_t offset,
 803                 char *addr, unsigned long count)
 804 {
 805         mm_segment_t old_fs;
 806         loff_t pos = offset;
 807         int result;
 808
 809         old_fs = get_fs();
 810         set_fs(get_ds());
 811         /* The cast to a user pointer is valid due to the set_fs() */
 812         result = vfs_read(file, (void __user *)addr, count, &pos);
 813         set_fs(old_fs);
 814         return result;
 815 }
 816
 817 EXPORT_SYMBOL(kernel_read);
 818
 819 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
 820 {
 821         ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
 822         if (res > 0)
 823                 flush_icache_range(addr, addr + len);
 824         return res;
 825 }
 826 EXPORT_SYMBOL(read_code);
 827
 828 static int exec_mmap(struct mm_struct *mm)
 829 {
 830         struct task_struct *tsk;
 831         struct mm_struct *old_mm, *active_mm;
 832
 833         /* Notify parent that we're no longer interested in the old VM */
 834         tsk = current;
 835         old_mm = current->mm;
 836         mm_release(tsk, old_mm);
 837
 838         if (old_mm) {
 839                 sync_mm_rss(old_mm);
 840                 /*
 841                  * Make sure that if there is a core dump in progress
 842                  * for the old mm, we get out and die instead of going
 843                  * through with the exec.  We must hold mmap_sem around
 844                  * checking core_state and changing tsk->mm.
 845                  */
 846                 down_read(&old_mm->mmap_sem);
 847                 if (unlikely(old_mm->core_state)) {
 848                         up_read(&old_mm->mmap_sem);
 849                         return -EINTR;
 850                 }
 851         }
 852         task_lock(tsk);
 853         active_mm = tsk->active_mm;
 854         tsk->mm = mm;
 855         tsk->active_mm = mm;
 856         activate_mm(active_mm, mm);
 857         tsk->mm->vmacache_seqnum = 0;
 858         vmacache_flush(tsk);
 859         task_unlock(tsk);
 860         if (old_mm) {
 861                 up_read(&old_mm->mmap_sem);
 862                 BUG_ON(active_mm != old_mm);
 863                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
 864                 mm_update_next_owner(old_mm);
 865                 mmput(old_mm);
 866                 return 0;
 867         }
 868         mmdrop(active_mm);
 869         return 0;
 870 }
 871
 872 /*
 873  * This function makes sure the current process has its own signal table,
 874  * so that flush_signal_handlers can later reset the handlers without
 875  * disturbing other processes.  (Other processes might share the signal
 876  * table via the CLONE_SIGHAND option to clone().)
 877  */
 878 static int de_thread(struct task_struct *tsk)
 879 {
 880         struct signal_struct *sig = tsk->signal;
 881         struct sighand_struct *oldsighand = tsk->sighand;
 882         spinlock_t *lock = &oldsighand->siglock;
 883
 884         if (thread_group_empty(tsk))
 885                 goto no_thread_group;
 886
 887         /*
 888          * Kill all other threads in the thread group.
 889          */
 890         spin_lock_irq(lock);
 891         if (signal_group_exit(sig)) {
 892                 /*
 893                  * Another group action in progress, just
 894                  * return so that the signal is processed.
 895                  */
 896                 spin_unlock_irq(lock);
 897                 return -EAGAIN;
 898         }
 899
 900         sig->group_exit_task = tsk;
 901         sig->notify_count = zap_other_threads(tsk);
 902         if (!thread_group_leader(tsk))
 903                 sig->notify_count--;
 904
 905         while (sig->notify_count) {
 906                 __set_current_state(TASK_KILLABLE);
 907                 spin_unlock_irq(lock);
 908                 schedule();
 909                 if (unlikely(__fatal_signal_pending(tsk)))
 910                         goto killed;
 911                 spin_lock_irq(lock);
 912         }
 913         spin_unlock_irq(lock);
 914
 915         /*
 916          * At this point all other threads have exited, all we have to
 917          * do is to wait for the thread group leader to become inactive,
 918          * and to assume its PID:
 919          */
 920         if (!thread_group_leader(tsk)) {
 921                 struct task_struct *leader = tsk->group_leader;
 922
 923                 sig->notify_count = -1; /* for exit_notify() */
 924                 for (;;) {
 925                         threadgroup_change_begin(tsk);
 926                         write_lock_irq(&tasklist_lock);
 927                         if (likely(leader->exit_state))
 928                                 break;
 929                         __set_current_state(TASK_KILLABLE);
 930                         write_unlock_irq(&tasklist_lock);
 931                         threadgroup_change_end(tsk);
 932                         schedule();
 933                         if (unlikely(__fatal_signal_pending(tsk)))
 934                                 goto killed;
 935                 }
 936
 937                 /*
 938                  * The only record we have of the real-time age of a
 939                  * process, regardless of execs it's done, is start_time.
 940                  * All the past CPU time is accumulated in signal_struct
 941                  * from sister threads now dead.  But in this non-leader
 942                  * exec, nothing survives from the original leader thread,
 943                  * whose birth marks the true age of this process now.
 944                  * When we take on its identity by switching to its PID, we
 945                  * also take its birthdate (always earlier than our own).
 946                  */
 947                 tsk->start_time = leader->start_time;
 948                 tsk->real_start_time = leader->real_start_time;
 949
 950                 BUG_ON(!same_thread_group(leader, tsk));
 951                 BUG_ON(has_group_leader_pid(tsk));
 952                 /*
 953                  * An exec() starts a new thread group with the
 954                  * TGID of the previous thread group. Rehash the
 955                  * two threads with a switched PID, and release
 956                  * the former thread group leader:
 957                  */
 958
 959                 /* Become a process group leader with the old leader's pid.
 960                  * The old leader becomes a thread of the this thread group.
 961                  * Note: The old leader also uses this pid until release_task
 962                  *       is called.  Odd but simple and correct.
 963                  */
 964                 tsk->pid = leader->pid;
 965                 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
 966                 transfer_pid(leader, tsk, PIDTYPE_PGID);
 967                 transfer_pid(leader, tsk, PIDTYPE_SID);
 968
 969                 list_replace_rcu(&leader->tasks, &tsk->tasks);
 970                 list_replace_init(&leader->sibling, &tsk->sibling);
 971
 972                 tsk->group_leader = tsk;
 973                 leader->group_leader = tsk;
 974
 975                 tsk->exit_signal = SIGCHLD;
 976                 leader->exit_signal = -1;
 977
 978                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
 979                 leader->exit_state = EXIT_DEAD;
 980
 981                 /*
 982                  * We are going to release_task()->ptrace_unlink() silently,
 983                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
 984                  * the tracer wont't block again waiting for this thread.
 985                  */
 986                 if (unlikely(leader->ptrace))
 987                         __wake_up_parent(leader, leader->parent);
 988                 write_unlock_irq(&tasklist_lock);
 989                 threadgroup_change_end(tsk);
 990
 991                 release_task(leader);
 992         }
 993
 994         sig->group_exit_task = NULL;
 995         sig->notify_count = 0;
 996
 997 no_thread_group:
 998         /* we have changed execution domain */
 999         tsk->exit_signal = SIGCHLD;
1000
1001         exit_itimers(sig);
1002         flush_itimer_signals();
1003
1004         if (atomic_read(&oldsighand->count) != 1) {
1005                 struct sighand_struct *newsighand;
1006                 /*
1007                  * This ->sighand is shared with the CLONE_SIGHAND
1008                  * but not CLONE_THREAD task, switch to the new one.
1009                  */
1010                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1011                 if (!newsighand)
1012                         return -ENOMEM;
1013
1014                 atomic_set(&newsighand->count, 1);
1015                 memcpy(newsighand->action, oldsighand->action,
1016                        sizeof(newsighand->action));
1017
1018                 write_lock_irq(&tasklist_lock);
1019                 spin_lock(&oldsighand->siglock);
1020                 rcu_assign_pointer(tsk->sighand, newsighand);
1021                 spin_unlock(&oldsighand->siglock);
1022                 write_unlock_irq(&tasklist_lock);
1023
1024                 __cleanup_sighand(oldsighand);
1025         }
1026
1027         BUG_ON(!thread_group_leader(tsk));
1028         return 0;
1029
1030 killed:
1031         /* protects against exit_notify() and __exit_signal() */
1032         read_lock(&tasklist_lock);
1033         sig->group_exit_task = NULL;
1034         sig->notify_count = 0;
1035         read_unlock(&tasklist_lock);
1036         return -EAGAIN;
1037 }
1038
1039 char *get_task_comm(char *buf, struct task_struct *tsk)
1040 {
1041         /* buf must be at least sizeof(tsk->comm) in size */
1042         task_lock(tsk);
1043         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1044         task_unlock(tsk);
1045         return buf;
1046 }
1047 EXPORT_SYMBOL_GPL(get_task_comm);
1048
1049 /*
1050  * These functions flushes out all traces of the currently running executable
1051  * so that a new one can be started
1052  */
1053
1054 void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1055 {
1056         task_lock(tsk);
1057         trace_task_rename(tsk, buf);
1058         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1059         task_unlock(tsk);
1060         perf_event_comm(tsk, exec);
1061 }
1062
1063 int flush_old_exec(struct linux_binprm * bprm)
1064 {
1065         int retval;
1066
1067         /*
1068          * Make sure we have a private signal table and that
1069          * we are unassociated from the previous thread group.
1070          */
1071         retval = de_thread(current);
1072         if (retval)
1073                 goto out;
1074
1075         set_mm_exe_file(bprm->mm, bprm->file);
1076         /*
1077          * Release all of the old mmap stuff
1078          */
1079         acct_arg_size(bprm, 0);
1080         retval = exec_mmap(bprm->mm);
1081         if (retval)
1082                 goto out;
1083
1084         bprm->mm = NULL;                /* We're using it now */
1085
1086         set_fs(USER_DS);
1087         current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1088                                         PF_NOFREEZE | PF_NO_SETAFFINITY);
1089         flush_thread();
1090         current->personality &= ~bprm->per_clear;
1091
1092         return 0;
1093
1094 out:
1095         return retval;
1096 }
1097 EXPORT_SYMBOL(flush_old_exec);
1098
1099 void would_dump(struct linux_binprm *bprm, struct file *file)
1100 {
1101         if (inode_permission(file_inode(file), MAY_READ) < 0)
1102                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1103 }
1104 EXPORT_SYMBOL(would_dump);
1105
1106 void setup_new_exec(struct linux_binprm * bprm)
1107 {
1108         arch_pick_mmap_layout(current->mm);
1109
1110         /* This is the point of no return */
1111         current->sas_ss_sp = current->sas_ss_size = 0;
1112
1113         if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1114                 set_dumpable(current->mm, SUID_DUMP_USER);
1115         else
1116                 set_dumpable(current->mm, suid_dumpable);
1117
1118         perf_event_exec();
1119         __set_task_comm(current, kbasename(bprm->filename), true);
1120
1121         /* Set the new mm task size. We have to do that late because it may
1122          * depend on TIF_32BIT which is only updated in flush_thread() on
1123          * some architectures like powerpc
1124          */
1125         current->mm->task_size = TASK_SIZE;
1126
1127         /* install the new credentials */
1128         if (!uid_eq(bprm->cred->uid, current_euid()) ||
1129             !gid_eq(bprm->cred->gid, current_egid())) {
1130                 current->pdeath_signal = 0;
1131         } else {
1132                 would_dump(bprm, bprm->file);
1133                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1134                         set_dumpable(current->mm, suid_dumpable);
1135         }
1136
1137         /* An exec changes our domain. We are no longer part of the thread
1138            group */
1139         current->self_exec_id++;
1140         flush_signal_handlers(current, 0);
1141         do_close_on_exec(current->files);
1142 }
1143 EXPORT_SYMBOL(setup_new_exec);
1144
1145 /*
1146  * Prepare credentials and lock ->cred_guard_mutex.
1147  * install_exec_creds() commits the new creds and drops the lock.
1148  * Or, if exec fails before, free_bprm() should release ->cred and
1149  * and unlock.
1150  */
1151 int prepare_bprm_creds(struct linux_binprm *bprm)
1152 {
1153         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1154                 return -ERESTARTNOINTR;
1155
1156         bprm->cred = prepare_exec_creds();
1157         if (likely(bprm->cred))
1158                 return 0;
1159
1160         mutex_unlock(&current->signal->cred_guard_mutex);
1161         return -ENOMEM;
1162 }
1163
1164 static void free_bprm(struct linux_binprm *bprm)
1165 {
1166         free_arg_pages(bprm);
1167         if (bprm->cred) {
1168                 mutex_unlock(&current->signal->cred_guard_mutex);
1169                 abort_creds(bprm->cred);
1170         }
1171         if (bprm->file) {
1172                 allow_write_access(bprm->file);
1173                 fput(bprm->file);
1174         }
1175         /* If a binfmt changed the interp, free it. */
1176         if (bprm->interp != bprm->filename)
1177                 kfree(bprm->interp);
1178         kfree(bprm);
1179 }
1180
1181 int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1182 {
1183         /* If a binfmt changed the interp, free it first. */
1184         if (bprm->interp != bprm->filename)
1185                 kfree(bprm->interp);
1186         bprm->interp = kstrdup(interp, GFP_KERNEL);
1187         if (!bprm->interp)
1188                 return -ENOMEM;
1189         return 0;
1190 }
1191 EXPORT_SYMBOL(bprm_change_interp);
1192
1193 /*
1194  * install the new credentials for this executable
1195  */
1196 void install_exec_creds(struct linux_binprm *bprm)
1197 {
1198         security_bprm_committing_creds(bprm);
1199
1200         commit_creds(bprm->cred);
1201         bprm->cred = NULL;
1202
1203         /*
1204          * Disable monitoring for regular users
1205          * when executing setuid binaries. Must
1206          * wait until new credentials are committed
1207          * by commit_creds() above
1208          */
1209         if (get_dumpable(current->mm) != SUID_DUMP_USER)
1210                 perf_event_exit_task(current);
1211         /*
1212          * cred_guard_mutex must be held at least to this point to prevent
1213          * ptrace_attach() from altering our determination of the task's
1214          * credentials; any time after this it may be unlocked.
1215          */
1216         security_bprm_committed_creds(bprm);
1217         mutex_unlock(&current->signal->cred_guard_mutex);
1218 }
1219 EXPORT_SYMBOL(install_exec_creds);
1220
1221 /*
1222  * determine how safe it is to execute the proposed program
1223  * - the caller must hold ->cred_guard_mutex to protect against
1224  *   PTRACE_ATTACH or seccomp thread-sync
1225  */
1226 static void check_unsafe_exec(struct linux_binprm *bprm)
1227 {
1228         struct task_struct *p = current, *t;
1229         unsigned n_fs;
1230
1231         if (p->ptrace) {
1232                 if (p->ptrace & PT_PTRACE_CAP)
1233                         bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1234                 else
1235                         bprm->unsafe |= LSM_UNSAFE_PTRACE;
1236         }
1237
1238         /*
1239          * This isn't strictly necessary, but it makes it harder for LSMs to
1240          * mess up.
1241          */
1242         if (task_no_new_privs(current))
1243                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1244
1245         t = p;
1246         n_fs = 1;
1247         spin_lock(&p->fs->lock);
1248         rcu_read_lock();
1249         while_each_thread(p, t) {
1250                 if (t->fs == p->fs)
1251                         n_fs++;
1252         }
1253         rcu_read_unlock();
1254
1255         if (p->fs->users > n_fs)
1256                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1257         else
1258                 p->fs->in_exec = 1;
1259         spin_unlock(&p->fs->lock);
1260 }
1261
1262 /*
1263  * Fill the binprm structure from the inode.
1264  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1265  *
1266  * This may be called multiple times for binary chains (scripts for example).
1267  */
1268 int prepare_binprm(struct linux_binprm *bprm)
1269 {
1270         struct inode *inode = file_inode(bprm->file);
1271         umode_t mode = inode->i_mode;
1272         int retval;
1273
1274
1275         /* clear any previous set[ug]id data from a previous binary */
1276         bprm->cred->euid = current_euid();
1277         bprm->cred->egid = current_egid();
1278
1279         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1280             !task_no_new_privs(current) &&
1281             kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1282             kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1283                 /* Set-uid? */
1284                 if (mode & S_ISUID) {
1285                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1286                         bprm->cred->euid = inode->i_uid;
1287                 }
1288
1289                 /* Set-gid? */
1290                 /*
1291                  * If setgid is set but no group execute bit then this
1292                  * is a candidate for mandatory locking, not a setgid
1293                  * executable.
1294                  */
1295                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1296                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1297                         bprm->cred->egid = inode->i_gid;
1298                 }
1299         }
1300
1301         /* fill in binprm security blob */
1302         retval = security_bprm_set_creds(bprm);
1303         if (retval)
1304                 return retval;
1305         bprm->cred_prepared = 1;
1306
1307         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1308         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1309 }
1310
1311 EXPORT_SYMBOL(prepare_binprm);
1312
1313 /*
1314  * Arguments are '\0' separated strings found at the location bprm->p
1315  * points to; chop off the first by relocating brpm->p to right after
1316  * the first '\0' encountered.
1317  */
1318 int remove_arg_zero(struct linux_binprm *bprm)
1319 {
1320         int ret = 0;
1321         unsigned long offset;
1322         char *kaddr;
1323         struct page *page;
1324
1325         if (!bprm->argc)
1326                 return 0;
1327
1328         do {
1329                 offset = bprm->p & ~PAGE_MASK;
1330                 page = get_arg_page(bprm, bprm->p, 0);
1331                 if (!page) {
1332                         ret = -EFAULT;
1333                         goto out;
1334                 }
1335                 kaddr = kmap_atomic(page);
1336
1337                 for (; offset < PAGE_SIZE && kaddr[offset];
1338                                 offset++, bprm->p++)
1339                         ;
1340
1341                 kunmap_atomic(kaddr);
1342                 put_arg_page(page);
1343
1344                 if (offset == PAGE_SIZE)
1345                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1346         } while (offset == PAGE_SIZE);
1347
1348         bprm->p++;
1349         bprm->argc--;
1350         ret = 0;
1351
1352 out:
1353         return ret;
1354 }
1355 EXPORT_SYMBOL(remove_arg_zero);
1356
1357 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1358 /*
1359  * cycle the list of binary formats handler, until one recognizes the image
1360  */
1361 int search_binary_handler(struct linux_binprm *bprm)
1362 {
1363         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1364         struct linux_binfmt *fmt;
1365         int retval;
1366
1367         /* This allows 4 levels of binfmt rewrites before failing hard. */
1368         if (bprm->recursion_depth > 5)
1369                 return -ELOOP;
1370
1371         retval = security_bprm_check(bprm);
1372         if (retval)
1373                 return retval;
1374
1375         retval = -ENOENT;
1376  retry:
1377         read_lock(&binfmt_lock);
1378         list_for_each_entry(fmt, &formats, lh) {
1379                 if (!try_module_get(fmt->module))
1380                         continue;
1381                 read_unlock(&binfmt_lock);
1382                 bprm->recursion_depth++;
1383                 retval = fmt->load_binary(bprm);
1384                 read_lock(&binfmt_lock);
1385                 put_binfmt(fmt);
1386                 bprm->recursion_depth--;
1387                 if (retval < 0 && !bprm->mm) {
1388                         /* we got to flush_old_exec() and failed after it */
1389                         read_unlock(&binfmt_lock);
1390                         force_sigsegv(SIGSEGV, current);
1391                         return retval;
1392                 }
1393                 if (retval != -ENOEXEC || !bprm->file) {
1394                         read_unlock(&binfmt_lock);
1395                         return retval;
1396                 }
1397         }
1398         read_unlock(&binfmt_lock);
1399
1400         if (need_retry) {
1401                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1402                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1403                         return retval;
1404                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1405                         return retval;
1406                 need_retry = false;
1407                 goto retry;
1408         }
1409
1410         return retval;
1411 }
1412 EXPORT_SYMBOL(search_binary_handler);
1413
1414 static int exec_binprm(struct linux_binprm *bprm)
1415 {
1416         pid_t old_pid, old_vpid;
1417         int ret;
1418
1419         /* Need to fetch pid before load_binary changes it */
1420         old_pid = current->pid;
1421         rcu_read_lock();
1422         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1423         rcu_read_unlock();
1424
1425         ret = search_binary_handler(bprm);
1426         if (ret >= 0) {
1427                 audit_bprm(bprm);
1428                 trace_sched_process_exec(current, old_pid, bprm);
1429                 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1430                 proc_exec_connector(current);
1431         }
1432
1433         return ret;
1434 }
1435
1436 /*
1437  * sys_execve() executes a new program.
1438  */
1439 static int do_execveat_common(int fd, struct filename *filename,
1440                               struct user_arg_ptr argv,
1441                               struct user_arg_ptr envp,
1442                               int flags)
1443 {
1444         char *pathbuf = NULL;
1445         struct linux_binprm *bprm;
1446         struct file *file;
1447         struct files_struct *displaced;
1448         int retval;
1449
1450         if (IS_ERR(filename))
1451                 return PTR_ERR(filename);
1452
1453         /*
1454          * We move the actual failure in case of RLIMIT_NPROC excess from
1455          * set*uid() to execve() because too many poorly written programs
1456          * don't check setuid() return code.  Here we additionally recheck
1457          * whether NPROC limit is still exceeded.
1458          */
1459         if ((current->flags & PF_NPROC_EXCEEDED) &&
1460             atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1461                 retval = -EAGAIN;
1462                 goto out_ret;
1463         }
1464
1465         /* We're below the limit (still or again), so we don't want to make
1466          * further execve() calls fail. */
1467         current->flags &= ~PF_NPROC_EXCEEDED;
1468
1469         retval = unshare_files(&displaced);
1470         if (retval)
1471                 goto out_ret;
1472
1473         retval = -ENOMEM;
1474         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1475         if (!bprm)
1476                 goto out_files;
1477
1478         retval = prepare_bprm_creds(bprm);
1479         if (retval)
1480                 goto out_free;
1481
1482         check_unsafe_exec(bprm);
1483         current->in_execve = 1;
1484
1485         file = do_open_execat(fd, filename, flags);
1486         retval = PTR_ERR(file);
1487         if (IS_ERR(file))
1488                 goto out_unmark;
1489
1490         sched_exec();
1491
1492         bprm->file = file;
1493         if (fd == AT_FDCWD || filename->name[0] == '/') {
1494                 bprm->filename = filename->name;
1495         } else {
1496                 if (filename->name[0] == '\0')
1497                         pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1498                 else
1499                         pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1500                                             fd, filename->name);
1501                 if (!pathbuf) {
1502                         retval = -ENOMEM;
1503                         goto out_unmark;
1504                 }
1505                 /*
1506                  * Record that a name derived from an O_CLOEXEC fd will be
1507                  * inaccessible after exec. Relies on having exclusive access to
1508                  * current->files (due to unshare_files above).
1509                  */
1510                 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1511                         bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1512                 bprm->filename = pathbuf;
1513         }
1514         bprm->interp = bprm->filename;
1515
1516         retval = bprm_mm_init(bprm);
1517         if (retval)
1518                 goto out_unmark;
1519
1520         bprm->argc = count(argv, MAX_ARG_STRINGS);
1521         if ((retval = bprm->argc) < 0)
1522                 goto out;
1523
1524         bprm->envc = count(envp, MAX_ARG_STRINGS);
1525         if ((retval = bprm->envc) < 0)
1526                 goto out;
1527
1528         retval = prepare_binprm(bprm);
1529         if (retval < 0)
1530                 goto out;
1531
1532         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1533         if (retval < 0)
1534                 goto out;
1535
1536         bprm->exec = bprm->p;
1537         retval = copy_strings(bprm->envc, envp, bprm);
1538         if (retval < 0)
1539                 goto out;
1540
1541         retval = copy_strings(bprm->argc, argv, bprm);
1542         if (retval < 0)
1543                 goto out;
1544
1545         retval = exec_binprm(bprm);
1546         if (retval < 0)
1547                 goto out;
1548
1549         /* execve succeeded */
1550         current->fs->in_exec = 0;
1551         current->in_execve = 0;
1552         acct_update_integrals(current);
1553         task_numa_free(current);
1554         free_bprm(bprm);
1555         kfree(pathbuf);
1556         putname(filename);
1557         if (displaced)
1558                 put_files_struct(displaced);
1559         return retval;
1560
1561 out:
1562         if (bprm->mm) {
1563                 acct_arg_size(bprm, 0);
1564                 mmput(bprm->mm);
1565         }
1566
1567 out_unmark:
1568         current->fs->in_exec = 0;
1569         current->in_execve = 0;
1570
1571 out_free:
1572         free_bprm(bprm);
1573         kfree(pathbuf);
1574
1575 out_files:
1576         if (displaced)
1577                 reset_files_struct(displaced);
1578 out_ret:
1579         putname(filename);
1580         return retval;
1581 }
1582
1583 int do_execve(struct filename *filename,
1584         const char __user *const __user *__argv,
1585         const char __user *const __user *__envp)
1586 {
1587         struct user_arg_ptr argv = { .ptr.native = __argv };
1588         struct user_arg_ptr envp = { .ptr.native = __envp };
1589         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1590 }
1591
1592 int do_execveat(int fd, struct filename *filename,
1593                 const char __user *const __user *__argv,
1594                 const char __user *const __user *__envp,
1595                 int flags)
1596 {
1597         struct user_arg_ptr argv = { .ptr.native = __argv };
1598         struct user_arg_ptr envp = { .ptr.native = __envp };
1599
1600         return do_execveat_common(fd, filename, argv, envp, flags);
1601 }
1602
1603 #ifdef CONFIG_COMPAT
1604 static int compat_do_execve(struct filename *filename,
1605         const compat_uptr_t __user *__argv,
1606         const compat_uptr_t __user *__envp)
1607 {
1608         struct user_arg_ptr argv = {
1609                 .is_compat = true,
1610                 .ptr.compat = __argv,
1611         };
1612         struct user_arg_ptr envp = {
1613                 .is_compat = true,
1614                 .ptr.compat = __envp,
1615         };
1616         return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1617 }
1618
1619 static int compat_do_execveat(int fd, struct filename *filename,
1620                               const compat_uptr_t __user *__argv,
1621                               const compat_uptr_t __user *__envp,
1622                               int flags)
1623 {
1624         struct user_arg_ptr argv = {
1625                 .is_compat = true,
1626                 .ptr.compat = __argv,
1627         };
1628         struct user_arg_ptr envp = {
1629                 .is_compat = true,
1630                 .ptr.compat = __envp,
1631         };
1632         return do_execveat_common(fd, filename, argv, envp, flags);
1633 }
1634 #endif
1635
1636 void set_binfmt(struct linux_binfmt *new)
1637 {
1638         struct mm_struct *mm = current->mm;
1639
1640         if (mm->binfmt)
1641                 module_put(mm->binfmt->module);
1642
1643         mm->binfmt = new;
1644         if (new)
1645                 __module_get(new->module);
1646 }
1647 EXPORT_SYMBOL(set_binfmt);
1648
1649 /*
1650  * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1651  */
1652 void set_dumpable(struct mm_struct *mm, int value)
1653 {
1654         unsigned long old, new;
1655
1656         if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1657                 return;
1658
1659         do {
1660                 old = ACCESS_ONCE(mm->flags);
1661                 new = (old & ~MMF_DUMPABLE_MASK) | value;
1662         } while (cmpxchg(&mm->flags, old, new) != old);
1663 }
1664
1665 SYSCALL_DEFINE3(execve,
1666                 const char __user *, filename,
1667                 const char __user *const __user *, argv,
1668                 const char __user *const __user *, envp)
1669 {
1670         return do_execve(getname(filename), argv, envp);
1671 }
1672
1673 SYSCALL_DEFINE5(execveat,
1674                 int, fd, const char __user *, filename,
1675                 const char __user *const __user *, argv,
1676                 const char __user *const __user *, envp,
1677                 int, flags)
1678 {
1679         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1680
1681         return do_execveat(fd,
1682                            getname_flags(filename, lookup_flags, NULL),
1683                            argv, envp, flags);
1684 }
1685
1686 #ifdef CONFIG_COMPAT
1687 COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1688         const compat_uptr_t __user *, argv,
1689         const compat_uptr_t __user *, envp)
1690 {
1691         return compat_do_execve(getname(filename), argv, envp);
1692 }
1693
1694 COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1695                        const char __user *, filename,
1696                        const compat_uptr_t __user *, argv,
1697                        const compat_uptr_t __user *, envp,
1698                        int,  flags)
1699 {
1700         int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1701
1702         return compat_do_execveat(fd,
1703                                   getname_flags(filename, lookup_flags, NULL),
1704                                   argv, envp, flags);
1705 }
1706 #endif