nilfs2: remove double bio_put() in nilfs_end_bio_write() for BIO_EOPNOTSUPP error
[linux-3.10.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         write_lock(&binfmt_lock);
78         insert ? list_add(&fmt->lh, &formats) :
79                  list_add_tail(&fmt->lh, &formats);
80         write_unlock(&binfmt_lock);
81 }
82
83 EXPORT_SYMBOL(__register_binfmt);
84
85 void unregister_binfmt(struct linux_binfmt * fmt)
86 {
87         write_lock(&binfmt_lock);
88         list_del(&fmt->lh);
89         write_unlock(&binfmt_lock);
90 }
91
92 EXPORT_SYMBOL(unregister_binfmt);
93
94 static inline void put_binfmt(struct linux_binfmt * fmt)
95 {
96         module_put(fmt->module);
97 }
98
99 /*
100  * Note that a shared library must be both readable and executable due to
101  * security reasons.
102  *
103  * Also note that we take the address to load from from the file itself.
104  */
105 SYSCALL_DEFINE1(uselib, const char __user *, library)
106 {
107         struct file *file;
108         struct filename *tmp = getname(library);
109         int error = PTR_ERR(tmp);
110         static const struct open_flags uselib_flags = {
111                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
112                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
113                 .intent = LOOKUP_OPEN
114         };
115
116         if (IS_ERR(tmp))
117                 goto out;
118
119         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
120         putname(tmp);
121         error = PTR_ERR(file);
122         if (IS_ERR(file))
123                 goto out;
124
125         error = -EINVAL;
126         if (!S_ISREG(file_inode(file)->i_mode))
127                 goto exit;
128
129         error = -EACCES;
130         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
131                 goto exit;
132
133         fsnotify_open(file);
134
135         error = -ENOEXEC;
136         if(file->f_op) {
137                 struct linux_binfmt * fmt;
138
139                 read_lock(&binfmt_lock);
140                 list_for_each_entry(fmt, &formats, lh) {
141                         if (!fmt->load_shlib)
142                                 continue;
143                         if (!try_module_get(fmt->module))
144                                 continue;
145                         read_unlock(&binfmt_lock);
146                         error = fmt->load_shlib(file);
147                         read_lock(&binfmt_lock);
148                         put_binfmt(fmt);
149                         if (error != -ENOEXEC)
150                                 break;
151                 }
152                 read_unlock(&binfmt_lock);
153         }
154 exit:
155         fput(file);
156 out:
157         return error;
158 }
159
160 #ifdef CONFIG_MMU
161 /*
162  * The nascent bprm->mm is not visible until exec_mmap() but it can
163  * use a lot of memory, account these pages in current->mm temporary
164  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
165  * change the counter back via acct_arg_size(0).
166  */
167 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
168 {
169         struct mm_struct *mm = current->mm;
170         long diff = (long)(pages - bprm->vma_pages);
171
172         if (!mm || !diff)
173                 return;
174
175         bprm->vma_pages = pages;
176         add_mm_counter(mm, MM_ANONPAGES, diff);
177 }
178
179 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
180                 int write)
181 {
182         struct page *page;
183         int ret;
184
185 #ifdef CONFIG_STACK_GROWSUP
186         if (write) {
187                 ret = expand_downwards(bprm->vma, pos);
188                 if (ret < 0)
189                         return NULL;
190         }
191 #endif
192         ret = get_user_pages(current, bprm->mm, pos,
193                         1, write, 1, &page, NULL);
194         if (ret <= 0)
195                 return NULL;
196
197         if (write) {
198                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
199                 struct rlimit *rlim;
200
201                 acct_arg_size(bprm, size / PAGE_SIZE);
202
203                 /*
204                  * We've historically supported up to 32 pages (ARG_MAX)
205                  * of argument strings even with small stacks
206                  */
207                 if (size <= ARG_MAX)
208                         return page;
209
210                 /*
211                  * Limit to 1/4-th the stack size for the argv+env strings.
212                  * This ensures that:
213                  *  - the remaining binfmt code will not run out of stack space,
214                  *  - the program will have a reasonable amount of stack left
215                  *    to work from.
216                  */
217                 rlim = current->signal->rlim;
218                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
219                         put_page(page);
220                         return NULL;
221                 }
222         }
223
224         return page;
225 }
226
227 static void put_arg_page(struct page *page)
228 {
229         put_page(page);
230 }
231
232 static void free_arg_page(struct linux_binprm *bprm, int i)
233 {
234 }
235
236 static void free_arg_pages(struct linux_binprm *bprm)
237 {
238 }
239
240 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
241                 struct page *page)
242 {
243         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
244 }
245
246 static int __bprm_mm_init(struct linux_binprm *bprm)
247 {
248         int err;
249         struct vm_area_struct *vma = NULL;
250         struct mm_struct *mm = bprm->mm;
251
252         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
253         if (!vma)
254                 return -ENOMEM;
255
256         down_write(&mm->mmap_sem);
257         vma->vm_mm = mm;
258
259         /*
260          * Place the stack at the largest stack address the architecture
261          * supports. Later, we'll move this to an appropriate place. We don't
262          * use STACK_TOP because that can depend on attributes which aren't
263          * configured yet.
264          */
265         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
266         vma->vm_end = STACK_TOP_MAX;
267         vma->vm_start = vma->vm_end - PAGE_SIZE;
268         vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
269         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
270         INIT_LIST_HEAD(&vma->anon_vma_chain);
271
272         err = insert_vm_struct(mm, vma);
273         if (err)
274                 goto err;
275
276         mm->stack_vm = mm->total_vm = 1;
277         up_write(&mm->mmap_sem);
278         bprm->p = vma->vm_end - sizeof(void *);
279         return 0;
280 err:
281         up_write(&mm->mmap_sem);
282         bprm->vma = NULL;
283         kmem_cache_free(vm_area_cachep, vma);
284         return err;
285 }
286
287 static bool valid_arg_len(struct linux_binprm *bprm, long len)
288 {
289         return len <= MAX_ARG_STRLEN;
290 }
291
292 #else
293
294 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
295 {
296 }
297
298 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
299                 int write)
300 {
301         struct page *page;
302
303         page = bprm->page[pos / PAGE_SIZE];
304         if (!page && write) {
305                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
306                 if (!page)
307                         return NULL;
308                 bprm->page[pos / PAGE_SIZE] = page;
309         }
310
311         return page;
312 }
313
314 static void put_arg_page(struct page *page)
315 {
316 }
317
318 static void free_arg_page(struct linux_binprm *bprm, int i)
319 {
320         if (bprm->page[i]) {
321                 __free_page(bprm->page[i]);
322                 bprm->page[i] = NULL;
323         }
324 }
325
326 static void free_arg_pages(struct linux_binprm *bprm)
327 {
328         int i;
329
330         for (i = 0; i < MAX_ARG_PAGES; i++)
331                 free_arg_page(bprm, i);
332 }
333
334 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
335                 struct page *page)
336 {
337 }
338
339 static int __bprm_mm_init(struct linux_binprm *bprm)
340 {
341         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
342         return 0;
343 }
344
345 static bool valid_arg_len(struct linux_binprm *bprm, long len)
346 {
347         return len <= bprm->p;
348 }
349
350 #endif /* CONFIG_MMU */
351
352 /*
353  * Create a new mm_struct and populate it with a temporary stack
354  * vm_area_struct.  We don't have enough context at this point to set the stack
355  * flags, permissions, and offset, so we use temporary values.  We'll update
356  * them later in setup_arg_pages().
357  */
358 static int bprm_mm_init(struct linux_binprm *bprm)
359 {
360         int err;
361         struct mm_struct *mm = NULL;
362
363         bprm->mm = mm = mm_alloc();
364         err = -ENOMEM;
365         if (!mm)
366                 goto err;
367
368         err = init_new_context(current, mm);
369         if (err)
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 to 1GB */
658         stack_base = rlimit_max(RLIMIT_STACK);
659         if (stack_base > (1 << 30))
660                 stack_base = 1 << 30;
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 struct file *open_exec(const char *name)
752 {
753         struct file *file;
754         int err;
755         struct filename tmp = { .name = name };
756         static const struct open_flags open_exec_flags = {
757                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
758                 .acc_mode = MAY_EXEC | MAY_OPEN,
759                 .intent = LOOKUP_OPEN
760         };
761
762         file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags, LOOKUP_FOLLOW);
763         if (IS_ERR(file))
764                 goto out;
765
766         err = -EACCES;
767         if (!S_ISREG(file_inode(file)->i_mode))
768                 goto exit;
769
770         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
771                 goto exit;
772
773         fsnotify_open(file);
774
775         err = deny_write_access(file);
776         if (err)
777                 goto exit;
778
779 out:
780         return file;
781
782 exit:
783         fput(file);
784         return ERR_PTR(err);
785 }
786 EXPORT_SYMBOL(open_exec);
787
788 int kernel_read(struct file *file, loff_t offset,
789                 char *addr, unsigned long count)
790 {
791         mm_segment_t old_fs;
792         loff_t pos = offset;
793         int result;
794
795         old_fs = get_fs();
796         set_fs(get_ds());
797         /* The cast to a user pointer is valid due to the set_fs() */
798         result = vfs_read(file, (void __user *)addr, count, &pos);
799         set_fs(old_fs);
800         return result;
801 }
802
803 EXPORT_SYMBOL(kernel_read);
804
805 ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
806 {
807         ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos);
808         if (res > 0)
809                 flush_icache_range(addr, addr + len);
810         return res;
811 }
812 EXPORT_SYMBOL(read_code);
813
814 static int exec_mmap(struct mm_struct *mm)
815 {
816         struct task_struct *tsk;
817         struct mm_struct * old_mm, *active_mm;
818
819         /* Notify parent that we're no longer interested in the old VM */
820         tsk = current;
821         old_mm = current->mm;
822         mm_release(tsk, old_mm);
823
824         if (old_mm) {
825                 sync_mm_rss(old_mm);
826                 /*
827                  * Make sure that if there is a core dump in progress
828                  * for the old mm, we get out and die instead of going
829                  * through with the exec.  We must hold mmap_sem around
830                  * checking core_state and changing tsk->mm.
831                  */
832                 down_read(&old_mm->mmap_sem);
833                 if (unlikely(old_mm->core_state)) {
834                         up_read(&old_mm->mmap_sem);
835                         return -EINTR;
836                 }
837         }
838         task_lock(tsk);
839         active_mm = tsk->active_mm;
840         tsk->mm = mm;
841         tsk->active_mm = mm;
842         activate_mm(active_mm, mm);
843         task_unlock(tsk);
844         arch_pick_mmap_layout(mm);
845         if (old_mm) {
846                 up_read(&old_mm->mmap_sem);
847                 BUG_ON(active_mm != old_mm);
848                 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
849                 mm_update_next_owner(old_mm);
850                 mmput(old_mm);
851                 return 0;
852         }
853         mmdrop(active_mm);
854         return 0;
855 }
856
857 /*
858  * This function makes sure the current process has its own signal table,
859  * so that flush_signal_handlers can later reset the handlers without
860  * disturbing other processes.  (Other processes might share the signal
861  * table via the CLONE_SIGHAND option to clone().)
862  */
863 static int de_thread(struct task_struct *tsk)
864 {
865         struct signal_struct *sig = tsk->signal;
866         struct sighand_struct *oldsighand = tsk->sighand;
867         spinlock_t *lock = &oldsighand->siglock;
868
869         if (thread_group_empty(tsk))
870                 goto no_thread_group;
871
872         /*
873          * Kill all other threads in the thread group.
874          */
875         spin_lock_irq(lock);
876         if (signal_group_exit(sig)) {
877                 /*
878                  * Another group action in progress, just
879                  * return so that the signal is processed.
880                  */
881                 spin_unlock_irq(lock);
882                 return -EAGAIN;
883         }
884
885         sig->group_exit_task = tsk;
886         sig->notify_count = zap_other_threads(tsk);
887         if (!thread_group_leader(tsk))
888                 sig->notify_count--;
889
890         while (sig->notify_count) {
891                 __set_current_state(TASK_KILLABLE);
892                 spin_unlock_irq(lock);
893                 schedule();
894                 if (unlikely(__fatal_signal_pending(tsk)))
895                         goto killed;
896                 spin_lock_irq(lock);
897         }
898         spin_unlock_irq(lock);
899
900         /*
901          * At this point all other threads have exited, all we have to
902          * do is to wait for the thread group leader to become inactive,
903          * and to assume its PID:
904          */
905         if (!thread_group_leader(tsk)) {
906                 struct task_struct *leader = tsk->group_leader;
907
908                 sig->notify_count = -1; /* for exit_notify() */
909                 for (;;) {
910                         threadgroup_change_begin(tsk);
911                         write_lock_irq(&tasklist_lock);
912                         if (likely(leader->exit_state))
913                                 break;
914                         __set_current_state(TASK_KILLABLE);
915                         write_unlock_irq(&tasklist_lock);
916                         threadgroup_change_end(tsk);
917                         schedule();
918                         if (unlikely(__fatal_signal_pending(tsk)))
919                                 goto killed;
920                 }
921
922                 /*
923                  * The only record we have of the real-time age of a
924                  * process, regardless of execs it's done, is start_time.
925                  * All the past CPU time is accumulated in signal_struct
926                  * from sister threads now dead.  But in this non-leader
927                  * exec, nothing survives from the original leader thread,
928                  * whose birth marks the true age of this process now.
929                  * When we take on its identity by switching to its PID, we
930                  * also take its birthdate (always earlier than our own).
931                  */
932                 tsk->start_time = leader->start_time;
933
934                 BUG_ON(!same_thread_group(leader, tsk));
935                 BUG_ON(has_group_leader_pid(tsk));
936                 /*
937                  * An exec() starts a new thread group with the
938                  * TGID of the previous thread group. Rehash the
939                  * two threads with a switched PID, and release
940                  * the former thread group leader:
941                  */
942
943                 /* Become a process group leader with the old leader's pid.
944                  * The old leader becomes a thread of the this thread group.
945                  * Note: The old leader also uses this pid until release_task
946                  *       is called.  Odd but simple and correct.
947                  */
948                 detach_pid(tsk, PIDTYPE_PID);
949                 tsk->pid = leader->pid;
950                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
951                 transfer_pid(leader, tsk, PIDTYPE_PGID);
952                 transfer_pid(leader, tsk, PIDTYPE_SID);
953
954                 list_replace_rcu(&leader->tasks, &tsk->tasks);
955                 list_replace_init(&leader->sibling, &tsk->sibling);
956
957                 tsk->group_leader = tsk;
958                 leader->group_leader = tsk;
959
960                 tsk->exit_signal = SIGCHLD;
961                 leader->exit_signal = -1;
962
963                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
964                 leader->exit_state = EXIT_DEAD;
965
966                 /*
967                  * We are going to release_task()->ptrace_unlink() silently,
968                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
969                  * the tracer wont't block again waiting for this thread.
970                  */
971                 if (unlikely(leader->ptrace))
972                         __wake_up_parent(leader, leader->parent);
973                 write_unlock_irq(&tasklist_lock);
974                 threadgroup_change_end(tsk);
975
976                 release_task(leader);
977         }
978
979         sig->group_exit_task = NULL;
980         sig->notify_count = 0;
981
982 no_thread_group:
983         /* we have changed execution domain */
984         tsk->exit_signal = SIGCHLD;
985
986         exit_itimers(sig);
987         flush_itimer_signals();
988
989         if (atomic_read(&oldsighand->count) != 1) {
990                 struct sighand_struct *newsighand;
991                 /*
992                  * This ->sighand is shared with the CLONE_SIGHAND
993                  * but not CLONE_THREAD task, switch to the new one.
994                  */
995                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
996                 if (!newsighand)
997                         return -ENOMEM;
998
999                 atomic_set(&newsighand->count, 1);
1000                 memcpy(newsighand->action, oldsighand->action,
1001                        sizeof(newsighand->action));
1002
1003                 write_lock_irq(&tasklist_lock);
1004                 spin_lock(&oldsighand->siglock);
1005                 rcu_assign_pointer(tsk->sighand, newsighand);
1006                 spin_unlock(&oldsighand->siglock);
1007                 write_unlock_irq(&tasklist_lock);
1008
1009                 __cleanup_sighand(oldsighand);
1010         }
1011
1012         BUG_ON(!thread_group_leader(tsk));
1013         return 0;
1014
1015 killed:
1016         /* protects against exit_notify() and __exit_signal() */
1017         read_lock(&tasklist_lock);
1018         sig->group_exit_task = NULL;
1019         sig->notify_count = 0;
1020         read_unlock(&tasklist_lock);
1021         return -EAGAIN;
1022 }
1023
1024 char *get_task_comm(char *buf, struct task_struct *tsk)
1025 {
1026         /* buf must be at least sizeof(tsk->comm) in size */
1027         task_lock(tsk);
1028         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1029         task_unlock(tsk);
1030         return buf;
1031 }
1032 EXPORT_SYMBOL_GPL(get_task_comm);
1033
1034 /*
1035  * These functions flushes out all traces of the currently running executable
1036  * so that a new one can be started
1037  */
1038
1039 void set_task_comm(struct task_struct *tsk, char *buf)
1040 {
1041         task_lock(tsk);
1042         trace_task_rename(tsk, buf);
1043         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1044         task_unlock(tsk);
1045         perf_event_comm(tsk);
1046 }
1047
1048 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)
1049 {
1050         int i, ch;
1051
1052         /* Copies the binary name from after last slash */
1053         for (i = 0; (ch = *(fn++)) != '\0';) {
1054                 if (ch == '/')
1055                         i = 0; /* overwrite what we wrote */
1056                 else
1057                         if (i < len - 1)
1058                                 tcomm[i++] = ch;
1059         }
1060         tcomm[i] = '\0';
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         filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));
1078         /*
1079          * Release all of the old mmap stuff
1080          */
1081         acct_arg_size(bprm, 0);
1082         retval = exec_mmap(bprm->mm);
1083         if (retval)
1084                 goto out;
1085
1086         bprm->mm = NULL;                /* We're using it now */
1087
1088         set_fs(USER_DS);
1089         current->flags &=
1090                 ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE);
1091         flush_thread();
1092         current->personality &= ~bprm->per_clear;
1093
1094         return 0;
1095
1096 out:
1097         return retval;
1098 }
1099 EXPORT_SYMBOL(flush_old_exec);
1100
1101 void would_dump(struct linux_binprm *bprm, struct file *file)
1102 {
1103         if (inode_permission(file_inode(file), MAY_READ) < 0)
1104                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1105 }
1106 EXPORT_SYMBOL(would_dump);
1107
1108 void setup_new_exec(struct linux_binprm * bprm)
1109 {
1110         arch_pick_mmap_layout(current->mm);
1111
1112         /* This is the point of no return */
1113         current->sas_ss_sp = current->sas_ss_size = 0;
1114
1115         if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1116                 set_dumpable(current->mm, SUID_DUMP_USER);
1117         else
1118                 set_dumpable(current->mm, suid_dumpable);
1119
1120         set_task_comm(current, bprm->tcomm);
1121
1122         /* Set the new mm task size. We have to do that late because it may
1123          * depend on TIF_32BIT which is only updated in flush_thread() on
1124          * some architectures like powerpc
1125          */
1126         current->mm->task_size = TASK_SIZE;
1127
1128         /* install the new credentials */
1129         if (!uid_eq(bprm->cred->uid, current_euid()) ||
1130             !gid_eq(bprm->cred->gid, current_egid())) {
1131                 current->pdeath_signal = 0;
1132         } else {
1133                 would_dump(bprm, bprm->file);
1134                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1135                         set_dumpable(current->mm, suid_dumpable);
1136         }
1137
1138         /* An exec changes our domain. We are no longer part of the thread
1139            group */
1140
1141         current->self_exec_id++;
1142                         
1143         flush_signal_handlers(current, 0);
1144         do_close_on_exec(current->files);
1145 }
1146 EXPORT_SYMBOL(setup_new_exec);
1147
1148 /*
1149  * Prepare credentials and lock ->cred_guard_mutex.
1150  * install_exec_creds() commits the new creds and drops the lock.
1151  * Or, if exec fails before, free_bprm() should release ->cred and
1152  * and unlock.
1153  */
1154 int prepare_bprm_creds(struct linux_binprm *bprm)
1155 {
1156         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1157                 return -ERESTARTNOINTR;
1158
1159         bprm->cred = prepare_exec_creds();
1160         if (likely(bprm->cred))
1161                 return 0;
1162
1163         mutex_unlock(&current->signal->cred_guard_mutex);
1164         return -ENOMEM;
1165 }
1166
1167 void free_bprm(struct linux_binprm *bprm)
1168 {
1169         free_arg_pages(bprm);
1170         if (bprm->cred) {
1171                 mutex_unlock(&current->signal->cred_guard_mutex);
1172                 abort_creds(bprm->cred);
1173         }
1174         /* If a binfmt changed the interp, free it. */
1175         if (bprm->interp != bprm->filename)
1176                 kfree(bprm->interp);
1177         kfree(bprm);
1178 }
1179
1180 int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1181 {
1182         /* If a binfmt changed the interp, free it first. */
1183         if (bprm->interp != bprm->filename)
1184                 kfree(bprm->interp);
1185         bprm->interp = kstrdup(interp, GFP_KERNEL);
1186         if (!bprm->interp)
1187                 return -ENOMEM;
1188         return 0;
1189 }
1190 EXPORT_SYMBOL(bprm_change_interp);
1191
1192 /*
1193  * install the new credentials for this executable
1194  */
1195 void install_exec_creds(struct linux_binprm *bprm)
1196 {
1197         security_bprm_committing_creds(bprm);
1198
1199         commit_creds(bprm->cred);
1200         bprm->cred = NULL;
1201
1202         /*
1203          * Disable monitoring for regular users
1204          * when executing setuid binaries. Must
1205          * wait until new credentials are committed
1206          * by commit_creds() above
1207          */
1208         if (get_dumpable(current->mm) != SUID_DUMP_USER)
1209                 perf_event_exit_task(current);
1210         /*
1211          * cred_guard_mutex must be held at least to this point to prevent
1212          * ptrace_attach() from altering our determination of the task's
1213          * credentials; any time after this it may be unlocked.
1214          */
1215         security_bprm_committed_creds(bprm);
1216         mutex_unlock(&current->signal->cred_guard_mutex);
1217 }
1218 EXPORT_SYMBOL(install_exec_creds);
1219
1220 /*
1221  * determine how safe it is to execute the proposed program
1222  * - the caller must hold ->cred_guard_mutex to protect against
1223  *   PTRACE_ATTACH
1224  */
1225 static int check_unsafe_exec(struct linux_binprm *bprm)
1226 {
1227         struct task_struct *p = current, *t;
1228         unsigned n_fs;
1229         int res = 0;
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 (current->no_new_privs)
1243                 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1244
1245         n_fs = 1;
1246         spin_lock(&p->fs->lock);
1247         rcu_read_lock();
1248         for (t = next_thread(p); t != p; t = next_thread(t)) {
1249                 if (t->fs == p->fs)
1250                         n_fs++;
1251         }
1252         rcu_read_unlock();
1253
1254         if (p->fs->users > n_fs) {
1255                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1256         } else {
1257                 res = -EAGAIN;
1258                 if (!p->fs->in_exec) {
1259                         p->fs->in_exec = 1;
1260                         res = 1;
1261                 }
1262         }
1263         spin_unlock(&p->fs->lock);
1264
1265         return res;
1266 }
1267
1268 /* 
1269  * Fill the binprm structure from the inode. 
1270  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1271  *
1272  * This may be called multiple times for binary chains (scripts for example).
1273  */
1274 int prepare_binprm(struct linux_binprm *bprm)
1275 {
1276         umode_t mode;
1277         struct inode * inode = file_inode(bprm->file);
1278         int retval;
1279
1280         mode = inode->i_mode;
1281         if (bprm->file->f_op == NULL)
1282                 return -EACCES;
1283
1284         /* clear any previous set[ug]id data from a previous binary */
1285         bprm->cred->euid = current_euid();
1286         bprm->cred->egid = current_egid();
1287
1288         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1289             !current->no_new_privs &&
1290             kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1291             kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1292                 /* Set-uid? */
1293                 if (mode & S_ISUID) {
1294                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1295                         bprm->cred->euid = inode->i_uid;
1296                 }
1297
1298                 /* Set-gid? */
1299                 /*
1300                  * If setgid is set but no group execute bit then this
1301                  * is a candidate for mandatory locking, not a setgid
1302                  * executable.
1303                  */
1304                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1305                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1306                         bprm->cred->egid = inode->i_gid;
1307                 }
1308         }
1309
1310         /* fill in binprm security blob */
1311         retval = security_bprm_set_creds(bprm);
1312         if (retval)
1313                 return retval;
1314         bprm->cred_prepared = 1;
1315
1316         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1317         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1318 }
1319
1320 EXPORT_SYMBOL(prepare_binprm);
1321
1322 /*
1323  * Arguments are '\0' separated strings found at the location bprm->p
1324  * points to; chop off the first by relocating brpm->p to right after
1325  * the first '\0' encountered.
1326  */
1327 int remove_arg_zero(struct linux_binprm *bprm)
1328 {
1329         int ret = 0;
1330         unsigned long offset;
1331         char *kaddr;
1332         struct page *page;
1333
1334         if (!bprm->argc)
1335                 return 0;
1336
1337         do {
1338                 offset = bprm->p & ~PAGE_MASK;
1339                 page = get_arg_page(bprm, bprm->p, 0);
1340                 if (!page) {
1341                         ret = -EFAULT;
1342                         goto out;
1343                 }
1344                 kaddr = kmap_atomic(page);
1345
1346                 for (; offset < PAGE_SIZE && kaddr[offset];
1347                                 offset++, bprm->p++)
1348                         ;
1349
1350                 kunmap_atomic(kaddr);
1351                 put_arg_page(page);
1352
1353                 if (offset == PAGE_SIZE)
1354                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1355         } while (offset == PAGE_SIZE);
1356
1357         bprm->p++;
1358         bprm->argc--;
1359         ret = 0;
1360
1361 out:
1362         return ret;
1363 }
1364 EXPORT_SYMBOL(remove_arg_zero);
1365
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         unsigned int depth = bprm->recursion_depth;
1372         int try,retval;
1373         struct linux_binfmt *fmt;
1374         pid_t old_pid, old_vpid;
1375
1376         /* This allows 4 levels of binfmt rewrites before failing hard. */
1377         if (depth > 5)
1378                 return -ELOOP;
1379
1380         retval = security_bprm_check(bprm);
1381         if (retval)
1382                 return retval;
1383
1384         retval = audit_bprm(bprm);
1385         if (retval)
1386                 return retval;
1387
1388         /* Need to fetch pid before load_binary changes it */
1389         old_pid = current->pid;
1390         rcu_read_lock();
1391         old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1392         rcu_read_unlock();
1393
1394         retval = -ENOENT;
1395         for (try=0; try<2; try++) {
1396                 read_lock(&binfmt_lock);
1397                 list_for_each_entry(fmt, &formats, lh) {
1398                         int (*fn)(struct linux_binprm *) = fmt->load_binary;
1399                         if (!fn)
1400                                 continue;
1401                         if (!try_module_get(fmt->module))
1402                                 continue;
1403                         read_unlock(&binfmt_lock);
1404                         bprm->recursion_depth = depth + 1;
1405                         retval = fn(bprm);
1406                         bprm->recursion_depth = depth;
1407                         if (retval >= 0) {
1408                                 if (depth == 0) {
1409                                         trace_sched_process_exec(current, old_pid, bprm);
1410                                         ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1411                                 }
1412                                 put_binfmt(fmt);
1413                                 allow_write_access(bprm->file);
1414                                 if (bprm->file)
1415                                         fput(bprm->file);
1416                                 bprm->file = NULL;
1417                                 current->did_exec = 1;
1418                                 proc_exec_connector(current);
1419                                 return retval;
1420                         }
1421                         read_lock(&binfmt_lock);
1422                         put_binfmt(fmt);
1423                         if (retval != -ENOEXEC || bprm->mm == NULL)
1424                                 break;
1425                         if (!bprm->file) {
1426                                 read_unlock(&binfmt_lock);
1427                                 return retval;
1428                         }
1429                 }
1430                 read_unlock(&binfmt_lock);
1431 #ifdef CONFIG_MODULES
1432                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1433                         break;
1434                 } else {
1435 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1436                         if (printable(bprm->buf[0]) &&
1437                             printable(bprm->buf[1]) &&
1438                             printable(bprm->buf[2]) &&
1439                             printable(bprm->buf[3]))
1440                                 break; /* -ENOEXEC */
1441                         if (try)
1442                                 break; /* -ENOEXEC */
1443                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1444                 }
1445 #else
1446                 break;
1447 #endif
1448         }
1449         return retval;
1450 }
1451
1452 EXPORT_SYMBOL(search_binary_handler);
1453
1454 /*
1455  * sys_execve() executes a new program.
1456  */
1457 static int do_execve_common(const char *filename,
1458                                 struct user_arg_ptr argv,
1459                                 struct user_arg_ptr envp)
1460 {
1461         struct linux_binprm *bprm;
1462         struct file *file;
1463         struct files_struct *displaced;
1464         bool clear_in_exec;
1465         int retval;
1466         const struct cred *cred = current_cred();
1467
1468         /*
1469          * We move the actual failure in case of RLIMIT_NPROC excess from
1470          * set*uid() to execve() because too many poorly written programs
1471          * don't check setuid() return code.  Here we additionally recheck
1472          * whether NPROC limit is still exceeded.
1473          */
1474         if ((current->flags & PF_NPROC_EXCEEDED) &&
1475             atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1476                 retval = -EAGAIN;
1477                 goto out_ret;
1478         }
1479
1480         /* We're below the limit (still or again), so we don't want to make
1481          * further execve() calls fail. */
1482         current->flags &= ~PF_NPROC_EXCEEDED;
1483
1484         retval = unshare_files(&displaced);
1485         if (retval)
1486                 goto out_ret;
1487
1488         retval = -ENOMEM;
1489         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1490         if (!bprm)
1491                 goto out_files;
1492
1493         retval = prepare_bprm_creds(bprm);
1494         if (retval)
1495                 goto out_free;
1496
1497         retval = check_unsafe_exec(bprm);
1498         if (retval < 0)
1499                 goto out_free;
1500         clear_in_exec = retval;
1501         current->in_execve = 1;
1502
1503         file = open_exec(filename);
1504         retval = PTR_ERR(file);
1505         if (IS_ERR(file))
1506                 goto out_unmark;
1507
1508         sched_exec();
1509
1510         bprm->file = file;
1511         bprm->filename = filename;
1512         bprm->interp = filename;
1513
1514         retval = bprm_mm_init(bprm);
1515         if (retval)
1516                 goto out_file;
1517
1518         bprm->argc = count(argv, MAX_ARG_STRINGS);
1519         if ((retval = bprm->argc) < 0)
1520                 goto out;
1521
1522         bprm->envc = count(envp, MAX_ARG_STRINGS);
1523         if ((retval = bprm->envc) < 0)
1524                 goto out;
1525
1526         retval = prepare_binprm(bprm);
1527         if (retval < 0)
1528                 goto out;
1529
1530         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1531         if (retval < 0)
1532                 goto out;
1533
1534         bprm->exec = bprm->p;
1535         retval = copy_strings(bprm->envc, envp, bprm);
1536         if (retval < 0)
1537                 goto out;
1538
1539         retval = copy_strings(bprm->argc, argv, bprm);
1540         if (retval < 0)
1541                 goto out;
1542
1543         retval = search_binary_handler(bprm);
1544         if (retval < 0)
1545                 goto out;
1546
1547         /* execve succeeded */
1548         current->fs->in_exec = 0;
1549         current->in_execve = 0;
1550         acct_update_integrals(current);
1551         free_bprm(bprm);
1552         if (displaced)
1553                 put_files_struct(displaced);
1554         return retval;
1555
1556 out:
1557         if (bprm->mm) {
1558                 acct_arg_size(bprm, 0);
1559                 mmput(bprm->mm);
1560         }
1561
1562 out_file:
1563         if (bprm->file) {
1564                 allow_write_access(bprm->file);
1565                 fput(bprm->file);
1566         }
1567
1568 out_unmark:
1569         if (clear_in_exec)
1570                 current->fs->in_exec = 0;
1571         current->in_execve = 0;
1572
1573 out_free:
1574         free_bprm(bprm);
1575
1576 out_files:
1577         if (displaced)
1578                 reset_files_struct(displaced);
1579 out_ret:
1580         return retval;
1581 }
1582
1583 int do_execve(const char *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_execve_common(filename, argv, envp);
1590 }
1591
1592 #ifdef CONFIG_COMPAT
1593 static int compat_do_execve(const char *filename,
1594         const compat_uptr_t __user *__argv,
1595         const compat_uptr_t __user *__envp)
1596 {
1597         struct user_arg_ptr argv = {
1598                 .is_compat = true,
1599                 .ptr.compat = __argv,
1600         };
1601         struct user_arg_ptr envp = {
1602                 .is_compat = true,
1603                 .ptr.compat = __envp,
1604         };
1605         return do_execve_common(filename, argv, envp);
1606 }
1607 #endif
1608
1609 void set_binfmt(struct linux_binfmt *new)
1610 {
1611         struct mm_struct *mm = current->mm;
1612
1613         if (mm->binfmt)
1614                 module_put(mm->binfmt->module);
1615
1616         mm->binfmt = new;
1617         if (new)
1618                 __module_get(new->module);
1619 }
1620
1621 EXPORT_SYMBOL(set_binfmt);
1622
1623 /*
1624  * set_dumpable converts traditional three-value dumpable to two flags and
1625  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1626  * these bits are not changed atomically.  So get_dumpable can observe the
1627  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1628  * return either old dumpable or new one by paying attention to the order of
1629  * modifying the bits.
1630  *
1631  * dumpable |   mm->flags (binary)
1632  * old  new | initial interim  final
1633  * ---------+-----------------------
1634  *  0    1  |   00      01      01
1635  *  0    2  |   00      10(*)   11
1636  *  1    0  |   01      00      00
1637  *  1    2  |   01      11      11
1638  *  2    0  |   11      10(*)   00
1639  *  2    1  |   11      11      01
1640  *
1641  * (*) get_dumpable regards interim value of 10 as 11.
1642  */
1643 void set_dumpable(struct mm_struct *mm, int value)
1644 {
1645         switch (value) {
1646         case SUID_DUMP_DISABLE:
1647                 clear_bit(MMF_DUMPABLE, &mm->flags);
1648                 smp_wmb();
1649                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1650                 break;
1651         case SUID_DUMP_USER:
1652                 set_bit(MMF_DUMPABLE, &mm->flags);
1653                 smp_wmb();
1654                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1655                 break;
1656         case SUID_DUMP_ROOT:
1657                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1658                 smp_wmb();
1659                 set_bit(MMF_DUMPABLE, &mm->flags);
1660                 break;
1661         }
1662 }
1663
1664 int __get_dumpable(unsigned long mm_flags)
1665 {
1666         int ret;
1667
1668         ret = mm_flags & MMF_DUMPABLE_MASK;
1669         return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
1670 }
1671
1672 int get_dumpable(struct mm_struct *mm)
1673 {
1674         return __get_dumpable(mm->flags);
1675 }
1676
1677 SYSCALL_DEFINE3(execve,
1678                 const char __user *, filename,
1679                 const char __user *const __user *, argv,
1680                 const char __user *const __user *, envp)
1681 {
1682         struct filename *path = getname(filename);
1683         int error = PTR_ERR(path);
1684         if (!IS_ERR(path)) {
1685                 error = do_execve(path->name, argv, envp);
1686                 putname(path);
1687         }
1688         return error;
1689 }
1690 #ifdef CONFIG_COMPAT
1691 asmlinkage long compat_sys_execve(const char __user * filename,
1692         const compat_uptr_t __user * argv,
1693         const compat_uptr_t __user * envp)
1694 {
1695         struct filename *path = getname(filename);
1696         int error = PTR_ERR(path);
1697         if (!IS_ERR(path)) {
1698                 error = compat_do_execve(path->name, argv, envp);
1699                 putname(path);
1700         }
1701         return error;
1702 }
1703 #endif