Merge branch 'master' of git://git.infradead.org/users/pcmoore/selinux into next
[linux-2.6-microblaze.git] / 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/stat.h>
30 #include <linux/fcntl.h>
31 #include <linux/swap.h>
32 #include <linux/string.h>
33 #include <linux/init.h>
34 #include <linux/pagemap.h>
35 #include <linux/perf_event.h>
36 #include <linux/highmem.h>
37 #include <linux/spinlock.h>
38 #include <linux/key.h>
39 #include <linux/personality.h>
40 #include <linux/binfmts.h>
41 #include <linux/utsname.h>
42 #include <linux/pid_namespace.h>
43 #include <linux/module.h>
44 #include <linux/namei.h>
45 #include <linux/mount.h>
46 #include <linux/security.h>
47 #include <linux/syscalls.h>
48 #include <linux/tsacct_kern.h>
49 #include <linux/cn_proc.h>
50 #include <linux/audit.h>
51 #include <linux/tracehook.h>
52 #include <linux/kmod.h>
53 #include <linux/fsnotify.h>
54 #include <linux/fs_struct.h>
55 #include <linux/pipe_fs_i.h>
56 #include <linux/oom.h>
57 #include <linux/compat.h>
58
59 #include <asm/uaccess.h>
60 #include <asm/mmu_context.h>
61 #include <asm/tlb.h>
62
63 #include <trace/events/task.h>
64 #include "internal.h"
65 #include "coredump.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 /*
102  * Note that a shared library must be both readable and executable due to
103  * security reasons.
104  *
105  * Also note that we take the address to load from from the file itself.
106  */
107 SYSCALL_DEFINE1(uselib, const char __user *, library)
108 {
109         struct linux_binfmt *fmt;
110         struct file *file;
111         struct filename *tmp = getname(library);
112         int error = PTR_ERR(tmp);
113         static const struct open_flags uselib_flags = {
114                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
115                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
116                 .intent = LOOKUP_OPEN,
117                 .lookup_flags = LOOKUP_FOLLOW,
118         };
119
120         if (IS_ERR(tmp))
121                 goto out;
122
123         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
124         putname(tmp);
125         error = PTR_ERR(file);
126         if (IS_ERR(file))
127                 goto out;
128
129         error = -EINVAL;
130         if (!S_ISREG(file_inode(file)->i_mode))
131                 goto exit;
132
133         error = -EACCES;
134         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
135                 goto exit;
136
137         fsnotify_open(file);
138
139         error = -ENOEXEC;
140
141         read_lock(&binfmt_lock);
142         list_for_each_entry(fmt, &formats, lh) {
143                 if (!fmt->load_shlib)
144                         continue;
145                 if (!try_module_get(fmt->module))
146                         continue;
147                 read_unlock(&binfmt_lock);
148                 error = fmt->load_shlib(file);
149                 read_lock(&binfmt_lock);
150                 put_binfmt(fmt);
151                 if (error != -ENOEXEC)
152                         break;
153         }
154         read_unlock(&binfmt_lock);
155 exit:
156         fput(file);
157 out:
158         return error;
159 }
160
161 #ifdef CONFIG_MMU
162 /*
163  * The nascent bprm->mm is not visible until exec_mmap() but it can
164  * use a lot of memory, account these pages in current->mm temporary
165  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
166  * change the counter back via acct_arg_size(0).
167  */
168 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
169 {
170         struct mm_struct *mm = current->mm;
171         long diff = (long)(pages - bprm->vma_pages);
172
173         if (!mm || !diff)
174                 return;
175
176         bprm->vma_pages = pages;
177         add_mm_counter(mm, MM_ANONPAGES, diff);
178 }
179
180 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
181                 int write)
182 {
183         struct page *page;
184         int ret;
185
186 #ifdef CONFIG_STACK_GROWSUP
187         if (write) {
188                 ret = expand_downwards(bprm->vma, pos);
189                 if (ret < 0)
190                         return NULL;
191         }
192 #endif
193         ret = get_user_pages(current, bprm->mm, pos,
194                         1, write, 1, &page, NULL);
195         if (ret <= 0)
196                 return NULL;
197
198         if (write) {
199                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
200                 struct rlimit *rlim;
201
202                 acct_arg_size(bprm, size / PAGE_SIZE);
203
204                 /*
205                  * We've historically supported up to 32 pages (ARG_MAX)
206                  * of argument strings even with small stacks
207                  */
208                 if (size <= ARG_MAX)
209                         return page;
210
211                 /*
212                  * Limit to 1/4-th the stack size for the argv+env strings.
213                  * This ensures that:
214                  *  - the remaining binfmt code will not run out of stack space,
215                  *  - the program will have a reasonable amount of stack left
216                  *    to work from.
217                  */
218                 rlim = current->signal->rlim;
219                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
220                         put_page(page);
221                         return NULL;
222                 }
223         }
224
225         return page;
226 }
227
228 static void put_arg_page(struct page *page)
229 {
230         put_page(page);
231 }
232
233 static void free_arg_page(struct linux_binprm *bprm, int i)
234 {
235 }
236
237 static void free_arg_pages(struct linux_binprm *bprm)
238 {
239 }
240
241 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
242                 struct page *page)
243 {
244         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
245 }
246
247 static int __bprm_mm_init(struct linux_binprm *bprm)
248 {
249         int err;
250         struct vm_area_struct *vma = NULL;
251         struct mm_struct *mm = bprm->mm;
252
253         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
254         if (!vma)
255                 return -ENOMEM;
256
257         down_write(&mm->mmap_sem);
258         vma->vm_mm = mm;
259
260         /*
261          * Place the stack at the largest stack address the architecture
262          * supports. Later, we'll move this to an appropriate place. We don't
263          * use STACK_TOP because that can depend on attributes which aren't
264          * configured yet.
265          */
266         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
267         vma->vm_end = STACK_TOP_MAX;
268         vma->vm_start = vma->vm_end - PAGE_SIZE;
269         vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
270         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
271         INIT_LIST_HEAD(&vma->anon_vma_chain);
272
273         err = insert_vm_struct(mm, vma);
274         if (err)
275                 goto err;
276
277         mm->stack_vm = mm->total_vm = 1;
278         up_write(&mm->mmap_sem);
279         bprm->p = vma->vm_end - sizeof(void *);
280         return 0;
281 err:
282         up_write(&mm->mmap_sem);
283         bprm->vma = NULL;
284         kmem_cache_free(vm_area_cachep, vma);
285         return err;
286 }
287
288 static bool valid_arg_len(struct linux_binprm *bprm, long len)
289 {
290         return len <= MAX_ARG_STRLEN;
291 }
292
293 #else
294
295 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
296 {
297 }
298
299 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
300                 int write)
301 {
302         struct page *page;
303
304         page = bprm->page[pos / PAGE_SIZE];
305         if (!page && write) {
306                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
307                 if (!page)
308                         return NULL;
309                 bprm->page[pos / PAGE_SIZE] = page;
310         }
311
312         return page;
313 }
314
315 static void put_arg_page(struct page *page)
316 {
317 }
318
319 static void free_arg_page(struct linux_binprm *bprm, int i)
320 {
321         if (bprm->page[i]) {
322                 __free_page(bprm->page[i]);
323                 bprm->page[i] = NULL;
324         }
325 }
326
327 static void free_arg_pages(struct linux_binprm *bprm)
328 {
329         int i;
330
331         for (i = 0; i < MAX_ARG_PAGES; i++)
332                 free_arg_page(bprm, i);
333 }
334
335 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
336                 struct page *page)
337 {
338 }
339
340 static int __bprm_mm_init(struct linux_binprm *bprm)
341 {
342         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
343         return 0;
344 }
345
346 static bool valid_arg_len(struct linux_binprm *bprm, long len)
347 {
348         return len <= bprm->p;
349 }
350
351 #endif /* CONFIG_MMU */
352
353 /*
354  * Create a new mm_struct and populate it with a temporary stack
355  * vm_area_struct.  We don't have enough context at this point to set the stack
356  * flags, permissions, and offset, so we use temporary values.  We'll update
357  * them later in setup_arg_pages().
358  */
359 static int bprm_mm_init(struct linux_binprm *bprm)
360 {
361         int err;
362         struct mm_struct *mm = NULL;
363
364         bprm->mm = mm = mm_alloc();
365         err = -ENOMEM;
366         if (!mm)
367                 goto err;
368
369         err = init_new_context(current, mm);
370         if (err)
371                 goto err;
372
373         err = __bprm_mm_init(bprm);
374         if (err)
375                 goto err;
376
377         return 0;
378
379 err:
380         if (mm) {
381                 bprm->mm = NULL;
382                 mmdrop(mm);
383         }
384
385         return err;
386 }
387
388 struct user_arg_ptr {
389 #ifdef CONFIG_COMPAT
390         bool is_compat;
391 #endif
392         union {
393                 const char __user *const __user *native;
394 #ifdef CONFIG_COMPAT
395                 const compat_uptr_t __user *compat;
396 #endif
397         } ptr;
398 };
399
400 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
401 {
402         const char __user *native;
403
404 #ifdef CONFIG_COMPAT
405         if (unlikely(argv.is_compat)) {
406                 compat_uptr_t compat;
407
408                 if (get_user(compat, argv.ptr.compat + nr))
409                         return ERR_PTR(-EFAULT);
410
411                 return compat_ptr(compat);
412         }
413 #endif
414
415         if (get_user(native, argv.ptr.native + nr))
416                 return ERR_PTR(-EFAULT);
417
418         return native;
419 }
420
421 /*
422  * count() counts the number of strings in array ARGV.
423  */
424 static int count(struct user_arg_ptr argv, int max)
425 {
426         int i = 0;
427
428         if (argv.ptr.native != NULL) {
429                 for (;;) {
430                         const char __user *p = get_user_arg_ptr(argv, i);
431
432                         if (!p)
433                                 break;
434
435                         if (IS_ERR(p))
436                                 return -EFAULT;
437
438                         if (i >= max)
439                                 return -E2BIG;
440                         ++i;
441
442                         if (fatal_signal_pending(current))
443                                 return -ERESTARTNOHAND;
444                         cond_resched();
445                 }
446         }
447         return i;
448 }
449
450 /*
451  * 'copy_strings()' copies argument/environment strings from the old
452  * processes's memory to the new process's stack.  The call to get_user_pages()
453  * ensures the destination page is created and not swapped out.
454  */
455 static int copy_strings(int argc, struct user_arg_ptr argv,
456                         struct linux_binprm *bprm)
457 {
458         struct page *kmapped_page = NULL;
459         char *kaddr = NULL;
460         unsigned long kpos = 0;
461         int ret;
462
463         while (argc-- > 0) {
464                 const char __user *str;
465                 int len;
466                 unsigned long pos;
467
468                 ret = -EFAULT;
469                 str = get_user_arg_ptr(argv, argc);
470                 if (IS_ERR(str))
471                         goto out;
472
473                 len = strnlen_user(str, MAX_ARG_STRLEN);
474                 if (!len)
475                         goto out;
476
477                 ret = -E2BIG;
478                 if (!valid_arg_len(bprm, len))
479                         goto out;
480
481                 /* We're going to work our way backwords. */
482                 pos = bprm->p;
483                 str += len;
484                 bprm->p -= len;
485
486                 while (len > 0) {
487                         int offset, bytes_to_copy;
488
489                         if (fatal_signal_pending(current)) {
490                                 ret = -ERESTARTNOHAND;
491                                 goto out;
492                         }
493                         cond_resched();
494
495                         offset = pos % PAGE_SIZE;
496                         if (offset == 0)
497                                 offset = PAGE_SIZE;
498
499                         bytes_to_copy = offset;
500                         if (bytes_to_copy > len)
501                                 bytes_to_copy = len;
502
503                         offset -= bytes_to_copy;
504                         pos -= bytes_to_copy;
505                         str -= bytes_to_copy;
506                         len -= bytes_to_copy;
507
508                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
509                                 struct page *page;
510
511                                 page = get_arg_page(bprm, pos, 1);
512                                 if (!page) {
513                                         ret = -E2BIG;
514                                         goto out;
515                                 }
516
517                                 if (kmapped_page) {
518                                         flush_kernel_dcache_page(kmapped_page);
519                                         kunmap(kmapped_page);
520                                         put_arg_page(kmapped_page);
521                                 }
522                                 kmapped_page = page;
523                                 kaddr = kmap(kmapped_page);
524                                 kpos = pos & PAGE_MASK;
525                                 flush_arg_page(bprm, kpos, kmapped_page);
526                         }
527                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
528                                 ret = -EFAULT;
529                                 goto out;
530                         }
531                 }
532         }
533         ret = 0;
534 out:
535         if (kmapped_page) {
536                 flush_kernel_dcache_page(kmapped_page);
537                 kunmap(kmapped_page);
538                 put_arg_page(kmapped_page);
539         }
540         return ret;
541 }
542
543 /*
544  * Like copy_strings, but get argv and its values from kernel memory.
545  */
546 int copy_strings_kernel(int argc, const char *const *__argv,
547                         struct linux_binprm *bprm)
548 {
549         int r;
550         mm_segment_t oldfs = get_fs();
551         struct user_arg_ptr argv = {
552                 .ptr.native = (const char __user *const  __user *)__argv,
553         };
554
555         set_fs(KERNEL_DS);
556         r = copy_strings(argc, argv, bprm);
557         set_fs(oldfs);
558
559         return r;
560 }
561 EXPORT_SYMBOL(copy_strings_kernel);
562
563 #ifdef CONFIG_MMU
564
565 /*
566  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
567  * the binfmt code determines where the new stack should reside, we shift it to
568  * its final location.  The process proceeds as follows:
569  *
570  * 1) Use shift to calculate the new vma endpoints.
571  * 2) Extend vma to cover both the old and new ranges.  This ensures the
572  *    arguments passed to subsequent functions are consistent.
573  * 3) Move vma's page tables to the new range.
574  * 4) Free up any cleared pgd range.
575  * 5) Shrink the vma to cover only the new range.
576  */
577 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
578 {
579         struct mm_struct *mm = vma->vm_mm;
580         unsigned long old_start = vma->vm_start;
581         unsigned long old_end = vma->vm_end;
582         unsigned long length = old_end - old_start;
583         unsigned long new_start = old_start - shift;
584         unsigned long new_end = old_end - shift;
585         struct mmu_gather tlb;
586
587         BUG_ON(new_start > new_end);
588
589         /*
590          * ensure there are no vmas between where we want to go
591          * and where we are
592          */
593         if (vma != find_vma(mm, new_start))
594                 return -EFAULT;
595
596         /*
597          * cover the whole range: [new_start, old_end)
598          */
599         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
600                 return -ENOMEM;
601
602         /*
603          * move the page tables downwards, on failure we rely on
604          * process cleanup to remove whatever mess we made.
605          */
606         if (length != move_page_tables(vma, old_start,
607                                        vma, new_start, length, false))
608                 return -ENOMEM;
609
610         lru_add_drain();
611         tlb_gather_mmu(&tlb, mm, old_start, old_end);
612         if (new_end > old_start) {
613                 /*
614                  * when the old and new regions overlap clear from new_end.
615                  */
616                 free_pgd_range(&tlb, new_end, old_end, new_end,
617                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
618         } else {
619                 /*
620                  * otherwise, clean from old_start; this is done to not touch
621                  * the address space in [new_end, old_start) some architectures
622                  * have constraints on va-space that make this illegal (IA64) -
623                  * for the others its just a little faster.
624                  */
625                 free_pgd_range(&tlb, old_start, old_end, new_end,
626                         vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
627         }
628         tlb_finish_mmu(&tlb, old_start, old_end);
629
630         /*
631          * Shrink the vma to just the new range.  Always succeeds.
632          */
633         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
634
635         return 0;
636 }
637
638 /*
639  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
640  * the stack is optionally relocated, and some extra space is added.
641  */
642 int setup_arg_pages(struct linux_binprm *bprm,
643                     unsigned long stack_top,
644                     int executable_stack)
645 {
646         unsigned long ret;
647         unsigned long stack_shift;
648         struct mm_struct *mm = current->mm;
649         struct vm_area_struct *vma = bprm->vma;
650         struct vm_area_struct *prev = NULL;
651         unsigned long vm_flags;
652         unsigned long stack_base;
653         unsigned long stack_size;
654         unsigned long stack_expand;
655         unsigned long rlim_stack;
656
657 #ifdef CONFIG_STACK_GROWSUP
658         /* Limit stack size to 1GB */
659         stack_base = rlimit_max(RLIMIT_STACK);
660         if (stack_base > (1 << 30))
661                 stack_base = 1 << 30;
662
663         /* Make sure we didn't let the argument array grow too large. */
664         if (vma->vm_end - vma->vm_start > stack_base)
665                 return -ENOMEM;
666
667         stack_base = PAGE_ALIGN(stack_top - stack_base);
668
669         stack_shift = vma->vm_start - stack_base;
670         mm->arg_start = bprm->p - stack_shift;
671         bprm->p = vma->vm_end - stack_shift;
672 #else
673         stack_top = arch_align_stack(stack_top);
674         stack_top = PAGE_ALIGN(stack_top);
675
676         if (unlikely(stack_top < mmap_min_addr) ||
677             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
678                 return -ENOMEM;
679
680         stack_shift = vma->vm_end - stack_top;
681
682         bprm->p -= stack_shift;
683         mm->arg_start = bprm->p;
684 #endif
685
686         if (bprm->loader)
687                 bprm->loader -= stack_shift;
688         bprm->exec -= stack_shift;
689
690         down_write(&mm->mmap_sem);
691         vm_flags = VM_STACK_FLAGS;
692
693         /*
694          * Adjust stack execute permissions; explicitly enable for
695          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
696          * (arch default) otherwise.
697          */
698         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
699                 vm_flags |= VM_EXEC;
700         else if (executable_stack == EXSTACK_DISABLE_X)
701                 vm_flags &= ~VM_EXEC;
702         vm_flags |= mm->def_flags;
703         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
704
705         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
706                         vm_flags);
707         if (ret)
708                 goto out_unlock;
709         BUG_ON(prev != vma);
710
711         /* Move stack pages down in memory. */
712         if (stack_shift) {
713                 ret = shift_arg_pages(vma, stack_shift);
714                 if (ret)
715                         goto out_unlock;
716         }
717
718         /* mprotect_fixup is overkill to remove the temporary stack flags */
719         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
720
721         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
722         stack_size = vma->vm_end - vma->vm_start;
723         /*
724          * Align this down to a page boundary as expand_stack
725          * will align it up.
726          */
727         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
728 #ifdef CONFIG_STACK_GROWSUP
729         if (stack_size + stack_expand > rlim_stack)
730                 stack_base = vma->vm_start + rlim_stack;
731         else
732                 stack_base = vma->vm_end + stack_expand;
733 #else
734         if (stack_size + stack_expand > rlim_stack)
735                 stack_base = vma->vm_end - rlim_stack;
736         else
737                 stack_base = vma->vm_start - stack_expand;
738 #endif
739         current->mm->start_stack = bprm->p;
740         ret = expand_stack(vma, stack_base);
741         if (ret)
742                 ret = -EFAULT;
743
744 out_unlock:
745         up_write(&mm->mmap_sem);
746         return ret;
747 }
748 EXPORT_SYMBOL(setup_arg_pages);
749
750 #endif /* CONFIG_MMU */
751
752 struct file *open_exec(const char *name)
753 {
754         struct file *file;
755         int err;
756         struct filename tmp = { .name = name };
757         static const struct open_flags open_exec_flags = {
758                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
759                 .acc_mode = MAY_EXEC | MAY_OPEN,
760                 .intent = LOOKUP_OPEN,
761                 .lookup_flags = LOOKUP_FOLLOW,
762         };
763
764         file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags);
765         if (IS_ERR(file))
766                 goto out;
767
768         err = -EACCES;
769         if (!S_ISREG(file_inode(file)->i_mode))
770                 goto exit;
771
772         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
773                 goto exit;
774
775         fsnotify_open(file);
776
777         err = deny_write_access(file);
778         if (err)
779                 goto exit;
780
781 out:
782         return file;
783
784 exit:
785         fput(file);
786         return ERR_PTR(err);
787 }
788 EXPORT_SYMBOL(open_exec);
789
790 int kernel_read(struct file *file, loff_t offset,
791                 char *addr, unsigned long count)
792 {
793         mm_segment_t old_fs;
794         loff_t pos = offset;
795         int result;
796
797         old_fs = get_fs();
798         set_fs(get_ds());
799         /* The cast to a user pointer is valid due to the set_fs() */
800         result = vfs_read(file, (void __user *)addr, count, &pos);
801         set_fs(old_fs);
802         return result;
803 }
804
805 EXPORT_SYMBOL(kernel_read);
806
807 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
808 {
809         ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos);
810         if (res > 0)
811                 flush_icache_range(addr, addr + len);
812         return res;
813 }
814 EXPORT_SYMBOL(read_code);
815
816 static int exec_mmap(struct mm_struct *mm)
817 {
818         struct task_struct *tsk;
819         struct mm_struct * old_mm, *active_mm;
820
821         /* Notify parent that we're no longer interested in the old VM */
822         tsk = current;
823         old_mm = current->mm;
824         mm_release(tsk, old_mm);
825
826         if (old_mm) {
827                 sync_mm_rss(old_mm);
828                 /*
829                  * Make sure that if there is a core dump in progress
830                  * for the old mm, we get out and die instead of going
831                  * through with the exec.  We must hold mmap_sem around
832                  * checking core_state and changing tsk->mm.
833                  */
834                 down_read(&old_mm->mmap_sem);
835                 if (unlikely(old_mm->core_state)) {
836                         up_read(&old_mm->mmap_sem);
837                         return -EINTR;
838                 }
839         }
840         task_lock(tsk);
841         active_mm = tsk->active_mm;
842         tsk->mm = mm;
843         tsk->active_mm = mm;
844         activate_mm(active_mm, mm);
845         task_unlock(tsk);
846         arch_pick_mmap_layout(mm);
847         if (old_mm) {
848                 up_read(&old_mm->mmap_sem);
849                 BUG_ON(active_mm != old_mm);
850                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
851                 mm_update_next_owner(old_mm);
852                 mmput(old_mm);
853                 return 0;
854         }
855         mmdrop(active_mm);
856         return 0;
857 }
858
859 /*
860  * This function makes sure the current process has its own signal table,
861  * so that flush_signal_handlers can later reset the handlers without
862  * disturbing other processes.  (Other processes might share the signal
863  * table via the CLONE_SIGHAND option to clone().)
864  */
865 static int de_thread(struct task_struct *tsk)
866 {
867         struct signal_struct *sig = tsk->signal;
868         struct sighand_struct *oldsighand = tsk->sighand;
869         spinlock_t *lock = &oldsighand->siglock;
870
871         if (thread_group_empty(tsk))
872                 goto no_thread_group;
873
874         /*
875          * Kill all other threads in the thread group.
876          */
877         spin_lock_irq(lock);
878         if (signal_group_exit(sig)) {
879                 /*
880                  * Another group action in progress, just
881                  * return so that the signal is processed.
882                  */
883                 spin_unlock_irq(lock);
884                 return -EAGAIN;
885         }
886
887         sig->group_exit_task = tsk;
888         sig->notify_count = zap_other_threads(tsk);
889         if (!thread_group_leader(tsk))
890                 sig->notify_count--;
891
892         while (sig->notify_count) {
893                 __set_current_state(TASK_KILLABLE);
894                 spin_unlock_irq(lock);
895                 schedule();
896                 if (unlikely(__fatal_signal_pending(tsk)))
897                         goto killed;
898                 spin_lock_irq(lock);
899         }
900         spin_unlock_irq(lock);
901
902         /*
903          * At this point all other threads have exited, all we have to
904          * do is to wait for the thread group leader to become inactive,
905          * and to assume its PID:
906          */
907         if (!thread_group_leader(tsk)) {
908                 struct task_struct *leader = tsk->group_leader;
909
910                 sig->notify_count = -1; /* for exit_notify() */
911                 for (;;) {
912                         threadgroup_change_begin(tsk);
913                         write_lock_irq(&tasklist_lock);
914                         if (likely(leader->exit_state))
915                                 break;
916                         __set_current_state(TASK_KILLABLE);
917                         write_unlock_irq(&tasklist_lock);
918                         threadgroup_change_end(tsk);
919                         schedule();
920                         if (unlikely(__fatal_signal_pending(tsk)))
921                                 goto killed;
922                 }
923
924                 /*
925                  * The only record we have of the real-time age of a
926                  * process, regardless of execs it's done, is start_time.
927                  * All the past CPU time is accumulated in signal_struct
928                  * from sister threads now dead.  But in this non-leader
929                  * exec, nothing survives from the original leader thread,
930                  * whose birth marks the true age of this process now.
931                  * When we take on its identity by switching to its PID, we
932                  * also take its birthdate (always earlier than our own).
933                  */
934                 tsk->start_time = leader->start_time;
935                 tsk->real_start_time = leader->real_start_time;
936
937                 BUG_ON(!same_thread_group(leader, tsk));
938                 BUG_ON(has_group_leader_pid(tsk));
939                 /*
940                  * An exec() starts a new thread group with the
941                  * TGID of the previous thread group. Rehash the
942                  * two threads with a switched PID, and release
943                  * the former thread group leader:
944                  */
945
946                 /* Become a process group leader with the old leader's pid.
947                  * The old leader becomes a thread of the this thread group.
948                  * Note: The old leader also uses this pid until release_task
949                  *       is called.  Odd but simple and correct.
950                  */
951                 tsk->pid = leader->pid;
952                 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
953                 transfer_pid(leader, tsk, PIDTYPE_PGID);
954                 transfer_pid(leader, tsk, PIDTYPE_SID);
955
956                 list_replace_rcu(&leader->tasks, &tsk->tasks);
957                 list_replace_init(&leader->sibling, &tsk->sibling);
958
959                 tsk->group_leader = tsk;
960                 leader->group_leader = tsk;
961
962                 tsk->exit_signal = SIGCHLD;
963                 leader->exit_signal = -1;
964
965                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
966                 leader->exit_state = EXIT_DEAD;
967
968                 /*
969                  * We are going to release_task()->ptrace_unlink() silently,
970                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
971                  * the tracer wont't block again waiting for this thread.
972                  */
973                 if (unlikely(leader->ptrace))
974                         __wake_up_parent(leader, leader->parent);
975                 write_unlock_irq(&tasklist_lock);
976                 threadgroup_change_end(tsk);
977
978                 release_task(leader);
979         }
980
981         sig->group_exit_task = NULL;
982         sig->notify_count = 0;
983
984 no_thread_group:
985         /* we have changed execution domain */
986         tsk->exit_signal = SIGCHLD;
987
988         exit_itimers(sig);
989         flush_itimer_signals();
990
991         if (atomic_read(&oldsighand->count) != 1) {
992                 struct sighand_struct *newsighand;
993                 /*
994                  * This ->sighand is shared with the CLONE_SIGHAND
995                  * but not CLONE_THREAD task, switch to the new one.
996                  */
997                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
998                 if (!newsighand)
999                         return -ENOMEM;
1000
1001                 atomic_set(&newsighand->count, 1);
1002                 memcpy(newsighand->action, oldsighand->action,
1003                        sizeof(newsighand->action));
1004
1005                 write_lock_irq(&tasklist_lock);
1006                 spin_lock(&oldsighand->siglock);
1007                 rcu_assign_pointer(tsk->sighand, newsighand);
1008                 spin_unlock(&oldsighand->siglock);
1009                 write_unlock_irq(&tasklist_lock);
1010
1011                 __cleanup_sighand(oldsighand);
1012         }
1013
1014         BUG_ON(!thread_group_leader(tsk));
1015         return 0;
1016
1017 killed:
1018         /* protects against exit_notify() and __exit_signal() */
1019         read_lock(&tasklist_lock);
1020         sig->group_exit_task = NULL;
1021         sig->notify_count = 0;
1022         read_unlock(&tasklist_lock);
1023         return -EAGAIN;
1024 }
1025
1026 char *get_task_comm(char *buf, struct task_struct *tsk)
1027 {
1028         /* buf must be at least sizeof(tsk->comm) in size */
1029         task_lock(tsk);
1030         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1031         task_unlock(tsk);
1032         return buf;
1033 }
1034 EXPORT_SYMBOL_GPL(get_task_comm);
1035
1036 /*
1037  * These functions flushes out all traces of the currently running executable
1038  * so that a new one can be started
1039  */
1040
1041 void set_task_comm(struct task_struct *tsk, char *buf)
1042 {
1043         task_lock(tsk);
1044         trace_task_rename(tsk, buf);
1045         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1046         task_unlock(tsk);
1047         perf_event_comm(tsk);
1048 }
1049
1050 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)
1051 {
1052         int i, ch;
1053
1054         /* Copies the binary name from after last slash */
1055         for (i = 0; (ch = *(fn++)) != '\0';) {
1056                 if (ch == '/')
1057                         i = 0; /* overwrite what we wrote */
1058                 else
1059                         if (i < len - 1)
1060                                 tcomm[i++] = ch;
1061         }
1062         tcomm[i] = '\0';
1063 }
1064
1065 int flush_old_exec(struct linux_binprm * bprm)
1066 {
1067         int retval;
1068
1069         /*
1070          * Make sure we have a private signal table and that
1071          * we are unassociated from the previous thread group.
1072          */
1073         retval = de_thread(current);
1074         if (retval)
1075                 goto out;
1076
1077         set_mm_exe_file(bprm->mm, bprm->file);
1078
1079         filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));
1080         /*
1081          * Release all of the old mmap stuff
1082          */
1083         acct_arg_size(bprm, 0);
1084         retval = exec_mmap(bprm->mm);
1085         if (retval)
1086                 goto out;
1087
1088         bprm->mm = NULL;                /* We're using it now */
1089
1090         set_fs(USER_DS);
1091         current->flags &=
1092                 ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE);
1093         flush_thread();
1094         current->personality &= ~bprm->per_clear;
1095
1096         return 0;
1097
1098 out:
1099         return retval;
1100 }
1101 EXPORT_SYMBOL(flush_old_exec);
1102
1103 void would_dump(struct linux_binprm *bprm, struct file *file)
1104 {
1105         if (inode_permission(file_inode(file), MAY_READ) < 0)
1106                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1107 }
1108 EXPORT_SYMBOL(would_dump);
1109
1110 void setup_new_exec(struct linux_binprm * bprm)
1111 {
1112         arch_pick_mmap_layout(current->mm);
1113
1114         /* This is the point of no return */
1115         current->sas_ss_sp = current->sas_ss_size = 0;
1116
1117         if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1118                 set_dumpable(current->mm, SUID_DUMP_USER);
1119         else
1120                 set_dumpable(current->mm, suid_dumpable);
1121
1122         set_task_comm(current, bprm->tcomm);
1123
1124         /* Set the new mm task size. We have to do that late because it may
1125          * depend on TIF_32BIT which is only updated in flush_thread() on
1126          * some architectures like powerpc
1127          */
1128         current->mm->task_size = TASK_SIZE;
1129
1130         /* install the new credentials */
1131         if (!uid_eq(bprm->cred->uid, current_euid()) ||
1132             !gid_eq(bprm->cred->gid, current_egid())) {
1133                 current->pdeath_signal = 0;
1134         } else {
1135                 would_dump(bprm, bprm->file);
1136                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1137                         set_dumpable(current->mm, suid_dumpable);
1138         }
1139
1140         /* An exec changes our domain. We are no longer part of the thread
1141            group */
1142
1143         current->self_exec_id++;
1144                         
1145         flush_signal_handlers(current, 0);
1146         do_close_on_exec(current->files);
1147 }
1148 EXPORT_SYMBOL(setup_new_exec);
1149
1150 /*
1151  * Prepare credentials and lock ->cred_guard_mutex.
1152  * install_exec_creds() commits the new creds and drops the lock.
1153  * Or, if exec fails before, free_bprm() should release ->cred and
1154  * and unlock.
1155  */
1156 int prepare_bprm_creds(struct linux_binprm *bprm)
1157 {
1158         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1159                 return -ERESTARTNOINTR;
1160
1161         bprm->cred = prepare_exec_creds();
1162         if (likely(bprm->cred))
1163                 return 0;
1164
1165         mutex_unlock(&current->signal->cred_guard_mutex);
1166         return -ENOMEM;
1167 }
1168
1169 void free_bprm(struct linux_binprm *bprm)
1170 {
1171         free_arg_pages(bprm);
1172         if (bprm->cred) {
1173                 mutex_unlock(&current->signal->cred_guard_mutex);
1174                 abort_creds(bprm->cred);
1175         }
1176         /* If a binfmt changed the interp, free it. */
1177         if (bprm->interp != bprm->filename)
1178                 kfree(bprm->interp);
1179         kfree(bprm);
1180 }
1181
1182 int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1183 {
1184         /* If a binfmt changed the interp, free it first. */
1185         if (bprm->interp != bprm->filename)
1186                 kfree(bprm->interp);
1187         bprm->interp = kstrdup(interp, GFP_KERNEL);
1188         if (!bprm->interp)
1189                 return -ENOMEM;
1190         return 0;
1191 }
1192 EXPORT_SYMBOL(bprm_change_interp);
1193
1194 /*
1195  * install the new credentials for this executable
1196  */
1197 void install_exec_creds(struct linux_binprm *bprm)
1198 {
1199         security_bprm_committing_creds(bprm);
1200
1201         commit_creds(bprm->cred);
1202         bprm->cred = NULL;
1203
1204         /*
1205          * Disable monitoring for regular users
1206          * when executing setuid binaries. Must
1207          * wait until new credentials are committed
1208          * by commit_creds() above
1209          */
1210         if (get_dumpable(current->mm) != SUID_DUMP_USER)
1211                 perf_event_exit_task(current);
1212         /*
1213          * cred_guard_mutex must be held at least to this point to prevent
1214          * ptrace_attach() from altering our determination of the task's
1215          * credentials; any time after this it may be unlocked.
1216          */
1217         security_bprm_committed_creds(bprm);
1218         mutex_unlock(&current->signal->cred_guard_mutex);
1219 }
1220 EXPORT_SYMBOL(install_exec_creds);
1221
1222 /*
1223  * determine how safe it is to execute the proposed program
1224  * - the caller must hold ->cred_guard_mutex to protect against
1225  *   PTRACE_ATTACH
1226  */
1227 static int check_unsafe_exec(struct linux_binprm *bprm)
1228 {
1229         struct task_struct *p = current, *t;
1230         unsigned n_fs;
1231         int res = 0;
1232
1233         if (p->ptrace) {
1234                 if (p->ptrace & PT_PTRACE_CAP)
1235                         bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1236                 else
1237                         bprm->unsafe |= LSM_UNSAFE_PTRACE;
1238         }
1239
1240         /*
1241          * This isn't strictly necessary, but it makes it harder for LSMs to
1242          * mess up.
1243          */
1244         if (current->no_new_privs)
1245                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1246
1247         n_fs = 1;
1248         spin_lock(&p->fs->lock);
1249         rcu_read_lock();
1250         for (t = next_thread(p); t != p; t = next_thread(t)) {
1251                 if (t->fs == p->fs)
1252                         n_fs++;
1253         }
1254         rcu_read_unlock();
1255
1256         if (p->fs->users > n_fs) {
1257                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1258         } else {
1259                 res = -EAGAIN;
1260                 if (!p->fs->in_exec) {
1261                         p->fs->in_exec = 1;
1262                         res = 1;
1263                 }
1264         }
1265         spin_unlock(&p->fs->lock);
1266
1267         return res;
1268 }
1269
1270 /* 
1271  * Fill the binprm structure from the inode. 
1272  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1273  *
1274  * This may be called multiple times for binary chains (scripts for example).
1275  */
1276 int prepare_binprm(struct linux_binprm *bprm)
1277 {
1278         struct inode *inode = file_inode(bprm->file);
1279         umode_t mode = inode->i_mode;
1280         int retval;
1281
1282
1283         /* clear any previous set[ug]id data from a previous binary */
1284         bprm->cred->euid = current_euid();
1285         bprm->cred->egid = current_egid();
1286
1287         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1288             !current->no_new_privs &&
1289             kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1290             kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1291                 /* Set-uid? */
1292                 if (mode & S_ISUID) {
1293                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1294                         bprm->cred->euid = inode->i_uid;
1295                 }
1296
1297                 /* Set-gid? */
1298                 /*
1299                  * If setgid is set but no group execute bit then this
1300                  * is a candidate for mandatory locking, not a setgid
1301                  * executable.
1302                  */
1303                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1304                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1305                         bprm->cred->egid = inode->i_gid;
1306                 }
1307         }
1308
1309         /* fill in binprm security blob */
1310         retval = security_bprm_set_creds(bprm);
1311         if (retval)
1312                 return retval;
1313         bprm->cred_prepared = 1;
1314
1315         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1316         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1317 }
1318
1319 EXPORT_SYMBOL(prepare_binprm);
1320
1321 /*
1322  * Arguments are '\0' separated strings found at the location bprm->p
1323  * points to; chop off the first by relocating brpm->p to right after
1324  * the first '\0' encountered.
1325  */
1326 int remove_arg_zero(struct linux_binprm *bprm)
1327 {
1328         int ret = 0;
1329         unsigned long offset;
1330         char *kaddr;
1331         struct page *page;
1332
1333         if (!bprm->argc)
1334                 return 0;
1335
1336         do {
1337                 offset = bprm->p & ~PAGE_MASK;
1338                 page = get_arg_page(bprm, bprm->p, 0);
1339                 if (!page) {
1340                         ret = -EFAULT;
1341                         goto out;
1342                 }
1343                 kaddr = kmap_atomic(page);
1344
1345                 for (; offset < PAGE_SIZE && kaddr[offset];
1346                                 offset++, bprm->p++)
1347                         ;
1348
1349                 kunmap_atomic(kaddr);
1350                 put_arg_page(page);
1351
1352                 if (offset == PAGE_SIZE)
1353                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1354         } while (offset == PAGE_SIZE);
1355
1356         bprm->p++;
1357         bprm->argc--;
1358         ret = 0;
1359
1360 out:
1361         return ret;
1362 }
1363 EXPORT_SYMBOL(remove_arg_zero);
1364
1365 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1366 /*
1367  * cycle the list of binary formats handler, until one recognizes the image
1368  */
1369 int search_binary_handler(struct linux_binprm *bprm)
1370 {
1371         bool need_retry = IS_ENABLED(CONFIG_MODULES);
1372         struct linux_binfmt *fmt;
1373         int retval;
1374
1375         /* This allows 4 levels of binfmt rewrites before failing hard. */
1376         if (bprm->recursion_depth > 5)
1377                 return -ELOOP;
1378
1379         retval = security_bprm_check(bprm);
1380         if (retval)
1381                 return retval;
1382
1383         retval = -ENOENT;
1384  retry:
1385         read_lock(&binfmt_lock);
1386         list_for_each_entry(fmt, &formats, lh) {
1387                 if (!try_module_get(fmt->module))
1388                         continue;
1389                 read_unlock(&binfmt_lock);
1390                 bprm->recursion_depth++;
1391                 retval = fmt->load_binary(bprm);
1392                 bprm->recursion_depth--;
1393                 if (retval >= 0 || retval != -ENOEXEC ||
1394                     bprm->mm == NULL || bprm->file == NULL) {
1395                         put_binfmt(fmt);
1396                         return retval;
1397                 }
1398                 read_lock(&binfmt_lock);
1399                 put_binfmt(fmt);
1400         }
1401         read_unlock(&binfmt_lock);
1402
1403         if (need_retry && retval == -ENOEXEC) {
1404                 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1405                     printable(bprm->buf[2]) && printable(bprm->buf[3]))
1406                         return retval;
1407                 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1408                         return retval;
1409                 need_retry = false;
1410                 goto retry;
1411         }
1412
1413         return retval;
1414 }
1415 EXPORT_SYMBOL(search_binary_handler);
1416
1417 static int exec_binprm(struct linux_binprm *bprm)
1418 {
1419         pid_t old_pid, old_vpid;
1420         int ret;
1421
1422         /* Need to fetch pid before load_binary changes it */
1423         old_pid = current->pid;
1424         rcu_read_lock();
1425         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1426         rcu_read_unlock();
1427
1428         ret = search_binary_handler(bprm);
1429         if (ret >= 0) {
1430                 audit_bprm(bprm);
1431                 trace_sched_process_exec(current, old_pid, bprm);
1432                 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1433                 current->did_exec = 1;
1434                 proc_exec_connector(current);
1435
1436                 if (bprm->file) {
1437                         allow_write_access(bprm->file);
1438                         fput(bprm->file);
1439                         bprm->file = NULL; /* to catch use-after-free */
1440                 }
1441         }
1442
1443         return ret;
1444 }
1445
1446 /*
1447  * sys_execve() executes a new program.
1448  */
1449 static int do_execve_common(const char *filename,
1450                                 struct user_arg_ptr argv,
1451                                 struct user_arg_ptr envp)
1452 {
1453         struct linux_binprm *bprm;
1454         struct file *file;
1455         struct files_struct *displaced;
1456         bool clear_in_exec;
1457         int retval;
1458
1459         /*
1460          * We move the actual failure in case of RLIMIT_NPROC excess from
1461          * set*uid() to execve() because too many poorly written programs
1462          * don't check setuid() return code.  Here we additionally recheck
1463          * whether NPROC limit is still exceeded.
1464          */
1465         if ((current->flags & PF_NPROC_EXCEEDED) &&
1466             atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1467                 retval = -EAGAIN;
1468                 goto out_ret;
1469         }
1470
1471         /* We're below the limit (still or again), so we don't want to make
1472          * further execve() calls fail. */
1473         current->flags &= ~PF_NPROC_EXCEEDED;
1474
1475         retval = unshare_files(&displaced);
1476         if (retval)
1477                 goto out_ret;
1478
1479         retval = -ENOMEM;
1480         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1481         if (!bprm)
1482                 goto out_files;
1483
1484         retval = prepare_bprm_creds(bprm);
1485         if (retval)
1486                 goto out_free;
1487
1488         retval = check_unsafe_exec(bprm);
1489         if (retval < 0)
1490                 goto out_free;
1491         clear_in_exec = retval;
1492         current->in_execve = 1;
1493
1494         file = open_exec(filename);
1495         retval = PTR_ERR(file);
1496         if (IS_ERR(file))
1497                 goto out_unmark;
1498
1499         sched_exec();
1500
1501         bprm->file = file;
1502         bprm->filename = filename;
1503         bprm->interp = filename;
1504
1505         retval = bprm_mm_init(bprm);
1506         if (retval)
1507                 goto out_file;
1508
1509         bprm->argc = count(argv, MAX_ARG_STRINGS);
1510         if ((retval = bprm->argc) < 0)
1511                 goto out;
1512
1513         bprm->envc = count(envp, MAX_ARG_STRINGS);
1514         if ((retval = bprm->envc) < 0)
1515                 goto out;
1516
1517         retval = prepare_binprm(bprm);
1518         if (retval < 0)
1519                 goto out;
1520
1521         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1522         if (retval < 0)
1523                 goto out;
1524
1525         bprm->exec = bprm->p;
1526         retval = copy_strings(bprm->envc, envp, bprm);
1527         if (retval < 0)
1528                 goto out;
1529
1530         retval = copy_strings(bprm->argc, argv, bprm);
1531         if (retval < 0)
1532                 goto out;
1533
1534         retval = exec_binprm(bprm);
1535         if (retval < 0)
1536                 goto out;
1537
1538         /* execve succeeded */
1539         current->fs->in_exec = 0;
1540         current->in_execve = 0;
1541         acct_update_integrals(current);
1542         task_numa_free(current);
1543         free_bprm(bprm);
1544         if (displaced)
1545                 put_files_struct(displaced);
1546         return retval;
1547
1548 out:
1549         if (bprm->mm) {
1550                 acct_arg_size(bprm, 0);
1551                 mmput(bprm->mm);
1552         }
1553
1554 out_file:
1555         if (bprm->file) {
1556                 allow_write_access(bprm->file);
1557                 fput(bprm->file);
1558         }
1559
1560 out_unmark:
1561         if (clear_in_exec)
1562                 current->fs->in_exec = 0;
1563         current->in_execve = 0;
1564
1565 out_free:
1566         free_bprm(bprm);
1567
1568 out_files:
1569         if (displaced)
1570                 reset_files_struct(displaced);
1571 out_ret:
1572         return retval;
1573 }
1574
1575 int do_execve(const char *filename,
1576         const char __user *const __user *__argv,
1577         const char __user *const __user *__envp)
1578 {
1579         struct user_arg_ptr argv = { .ptr.native = __argv };
1580         struct user_arg_ptr envp = { .ptr.native = __envp };
1581         return do_execve_common(filename, argv, envp);
1582 }
1583
1584 #ifdef CONFIG_COMPAT
1585 static int compat_do_execve(const char *filename,
1586         const compat_uptr_t __user *__argv,
1587         const compat_uptr_t __user *__envp)
1588 {
1589         struct user_arg_ptr argv = {
1590                 .is_compat = true,
1591                 .ptr.compat = __argv,
1592         };
1593         struct user_arg_ptr envp = {
1594                 .is_compat = true,
1595                 .ptr.compat = __envp,
1596         };
1597         return do_execve_common(filename, argv, envp);
1598 }
1599 #endif
1600
1601 void set_binfmt(struct linux_binfmt *new)
1602 {
1603         struct mm_struct *mm = current->mm;
1604
1605         if (mm->binfmt)
1606                 module_put(mm->binfmt->module);
1607
1608         mm->binfmt = new;
1609         if (new)
1610                 __module_get(new->module);
1611 }
1612
1613 EXPORT_SYMBOL(set_binfmt);
1614
1615 /*
1616  * set_dumpable converts traditional three-value dumpable to two flags and
1617  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1618  * these bits are not changed atomically.  So get_dumpable can observe the
1619  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1620  * return either old dumpable or new one by paying attention to the order of
1621  * modifying the bits.
1622  *
1623  * dumpable |   mm->flags (binary)
1624  * old  new | initial interim  final
1625  * ---------+-----------------------
1626  *  0    1  |   00      01      01
1627  *  0    2  |   00      10(*)   11
1628  *  1    0  |   01      00      00
1629  *  1    2  |   01      11      11
1630  *  2    0  |   11      10(*)   00
1631  *  2    1  |   11      11      01
1632  *
1633  * (*) get_dumpable regards interim value of 10 as 11.
1634  */
1635 void set_dumpable(struct mm_struct *mm, int value)
1636 {
1637         switch (value) {
1638         case SUID_DUMP_DISABLE:
1639                 clear_bit(MMF_DUMPABLE, &mm->flags);
1640                 smp_wmb();
1641                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1642                 break;
1643         case SUID_DUMP_USER:
1644                 set_bit(MMF_DUMPABLE, &mm->flags);
1645                 smp_wmb();
1646                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1647                 break;
1648         case SUID_DUMP_ROOT:
1649                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1650                 smp_wmb();
1651                 set_bit(MMF_DUMPABLE, &mm->flags);
1652                 break;
1653         }
1654 }
1655
1656 int __get_dumpable(unsigned long mm_flags)
1657 {
1658         int ret;
1659
1660         ret = mm_flags & MMF_DUMPABLE_MASK;
1661         return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
1662 }
1663
1664 /*
1665  * This returns the actual value of the suid_dumpable flag. For things
1666  * that are using this for checking for privilege transitions, it must
1667  * test against SUID_DUMP_USER rather than treating it as a boolean
1668  * value.
1669  */
1670 int get_dumpable(struct mm_struct *mm)
1671 {
1672         return __get_dumpable(mm->flags);
1673 }
1674
1675 SYSCALL_DEFINE3(execve,
1676                 const char __user *, filename,
1677                 const char __user *const __user *, argv,
1678                 const char __user *const __user *, envp)
1679 {
1680         struct filename *path = getname(filename);
1681         int error = PTR_ERR(path);
1682         if (!IS_ERR(path)) {
1683                 error = do_execve(path->name, argv, envp);
1684                 putname(path);
1685         }
1686         return error;
1687 }
1688 #ifdef CONFIG_COMPAT
1689 asmlinkage long compat_sys_execve(const char __user * filename,
1690         const compat_uptr_t __user * argv,
1691         const compat_uptr_t __user * envp)
1692 {
1693         struct filename *path = getname(filename);
1694         int error = PTR_ERR(path);
1695         if (!IS_ERR(path)) {
1696                 error = compat_do_execve(path->name, argv, envp);
1697                 putname(path);
1698         }
1699         return error;
1700 }
1701 #endif