aba5e13a6a68c7d3e0540f35c79c7c3a6f6404db
[pandora-kernel.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 #include "internal.h"
63
64 int core_uses_pid;
65 char core_pattern[CORENAME_MAX_SIZE] = "core";
66 unsigned int core_pipe_limit;
67 int suid_dumpable = 0;
68
69 struct core_name {
70         char *corename;
71         int used, size;
72 };
73 static atomic_t call_count = ATOMIC_INIT(1);
74
75 /* The maximal length of core_pattern is also specified in sysctl.c */
76
77 static LIST_HEAD(formats);
78 static DEFINE_RWLOCK(binfmt_lock);
79
80 int __register_binfmt(struct linux_binfmt * fmt, int insert)
81 {
82         if (!fmt)
83                 return -EINVAL;
84         write_lock(&binfmt_lock);
85         insert ? list_add(&fmt->lh, &formats) :
86                  list_add_tail(&fmt->lh, &formats);
87         write_unlock(&binfmt_lock);
88         return 0;       
89 }
90
91 EXPORT_SYMBOL(__register_binfmt);
92
93 void unregister_binfmt(struct linux_binfmt * fmt)
94 {
95         write_lock(&binfmt_lock);
96         list_del(&fmt->lh);
97         write_unlock(&binfmt_lock);
98 }
99
100 EXPORT_SYMBOL(unregister_binfmt);
101
102 static inline void put_binfmt(struct linux_binfmt * fmt)
103 {
104         module_put(fmt->module);
105 }
106
107 /*
108  * Note that a shared library must be both readable and executable due to
109  * security reasons.
110  *
111  * Also note that we take the address to load from from the file itself.
112  */
113 SYSCALL_DEFINE1(uselib, const char __user *, library)
114 {
115         struct file *file;
116         char *tmp = getname(library);
117         int error = PTR_ERR(tmp);
118         static const struct open_flags uselib_flags = {
119                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
120                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
121                 .intent = LOOKUP_OPEN
122         };
123
124         if (IS_ERR(tmp))
125                 goto out;
126
127         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
128         putname(tmp);
129         error = PTR_ERR(file);
130         if (IS_ERR(file))
131                 goto out;
132
133         error = -EINVAL;
134         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
135                 goto exit;
136
137         error = -EACCES;
138         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
139                 goto exit;
140
141         fsnotify_open(file);
142
143         error = -ENOEXEC;
144         if(file->f_op) {
145                 struct linux_binfmt * fmt;
146
147                 read_lock(&binfmt_lock);
148                 list_for_each_entry(fmt, &formats, lh) {
149                         if (!fmt->load_shlib)
150                                 continue;
151                         if (!try_module_get(fmt->module))
152                                 continue;
153                         read_unlock(&binfmt_lock);
154                         error = fmt->load_shlib(file);
155                         read_lock(&binfmt_lock);
156                         put_binfmt(fmt);
157                         if (error != -ENOEXEC)
158                                 break;
159                 }
160                 read_unlock(&binfmt_lock);
161         }
162 exit:
163         fput(file);
164 out:
165         return error;
166 }
167
168 #ifdef CONFIG_MMU
169 /*
170  * The nascent bprm->mm is not visible until exec_mmap() but it can
171  * use a lot of memory, account these pages in current->mm temporary
172  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
173  * change the counter back via acct_arg_size(0).
174  */
175 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
176 {
177         struct mm_struct *mm = current->mm;
178         long diff = (long)(pages - bprm->vma_pages);
179
180         if (!mm || !diff)
181                 return;
182
183         bprm->vma_pages = pages;
184         add_mm_counter(mm, MM_ANONPAGES, diff);
185 }
186
187 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
188                 int write)
189 {
190         struct page *page;
191         int ret;
192
193 #ifdef CONFIG_STACK_GROWSUP
194         if (write) {
195                 ret = expand_downwards(bprm->vma, pos);
196                 if (ret < 0)
197                         return NULL;
198         }
199 #endif
200         ret = get_user_pages(current, bprm->mm, pos,
201                         1, write, 1, &page, NULL);
202         if (ret <= 0)
203                 return NULL;
204
205         if (write) {
206                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
207                 struct rlimit *rlim;
208
209                 acct_arg_size(bprm, size / PAGE_SIZE);
210
211                 /*
212                  * We've historically supported up to 32 pages (ARG_MAX)
213                  * of argument strings even with small stacks
214                  */
215                 if (size <= ARG_MAX)
216                         return page;
217
218                 /*
219                  * Limit to 1/4-th the stack size for the argv+env strings.
220                  * This ensures that:
221                  *  - the remaining binfmt code will not run out of stack space,
222                  *  - the program will have a reasonable amount of stack left
223                  *    to work from.
224                  */
225                 rlim = current->signal->rlim;
226                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
227                         put_page(page);
228                         return NULL;
229                 }
230         }
231
232         return page;
233 }
234
235 static void put_arg_page(struct page *page)
236 {
237         put_page(page);
238 }
239
240 static void free_arg_page(struct linux_binprm *bprm, int i)
241 {
242 }
243
244 static void free_arg_pages(struct linux_binprm *bprm)
245 {
246 }
247
248 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
249                 struct page *page)
250 {
251         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
252 }
253
254 static int __bprm_mm_init(struct linux_binprm *bprm)
255 {
256         int err;
257         struct vm_area_struct *vma = NULL;
258         struct mm_struct *mm = bprm->mm;
259
260         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
261         if (!vma)
262                 return -ENOMEM;
263
264         down_write(&mm->mmap_sem);
265         vma->vm_mm = mm;
266
267         /*
268          * Place the stack at the largest stack address the architecture
269          * supports. Later, we'll move this to an appropriate place. We don't
270          * use STACK_TOP because that can depend on attributes which aren't
271          * configured yet.
272          */
273         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
274         vma->vm_end = STACK_TOP_MAX;
275         vma->vm_start = vma->vm_end - PAGE_SIZE;
276         vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
277         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
278         INIT_LIST_HEAD(&vma->anon_vma_chain);
279
280         err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
281         if (err)
282                 goto err;
283
284         err = insert_vm_struct(mm, vma);
285         if (err)
286                 goto err;
287
288         mm->stack_vm = mm->total_vm = 1;
289         up_write(&mm->mmap_sem);
290         bprm->p = vma->vm_end - sizeof(void *);
291         return 0;
292 err:
293         up_write(&mm->mmap_sem);
294         bprm->vma = NULL;
295         kmem_cache_free(vm_area_cachep, vma);
296         return err;
297 }
298
299 static bool valid_arg_len(struct linux_binprm *bprm, long len)
300 {
301         return len <= MAX_ARG_STRLEN;
302 }
303
304 #else
305
306 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
307 {
308 }
309
310 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
311                 int write)
312 {
313         struct page *page;
314
315         page = bprm->page[pos / PAGE_SIZE];
316         if (!page && write) {
317                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
318                 if (!page)
319                         return NULL;
320                 bprm->page[pos / PAGE_SIZE] = page;
321         }
322
323         return page;
324 }
325
326 static void put_arg_page(struct page *page)
327 {
328 }
329
330 static void free_arg_page(struct linux_binprm *bprm, int i)
331 {
332         if (bprm->page[i]) {
333                 __free_page(bprm->page[i]);
334                 bprm->page[i] = NULL;
335         }
336 }
337
338 static void free_arg_pages(struct linux_binprm *bprm)
339 {
340         int i;
341
342         for (i = 0; i < MAX_ARG_PAGES; i++)
343                 free_arg_page(bprm, i);
344 }
345
346 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
347                 struct page *page)
348 {
349 }
350
351 static int __bprm_mm_init(struct linux_binprm *bprm)
352 {
353         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
354         return 0;
355 }
356
357 static bool valid_arg_len(struct linux_binprm *bprm, long len)
358 {
359         return len <= bprm->p;
360 }
361
362 #endif /* CONFIG_MMU */
363
364 /*
365  * Create a new mm_struct and populate it with a temporary stack
366  * vm_area_struct.  We don't have enough context at this point to set the stack
367  * flags, permissions, and offset, so we use temporary values.  We'll update
368  * them later in setup_arg_pages().
369  */
370 int bprm_mm_init(struct linux_binprm *bprm)
371 {
372         int err;
373         struct mm_struct *mm = NULL;
374
375         bprm->mm = mm = mm_alloc();
376         err = -ENOMEM;
377         if (!mm)
378                 goto err;
379
380         err = init_new_context(current, mm);
381         if (err)
382                 goto err;
383
384         err = __bprm_mm_init(bprm);
385         if (err)
386                 goto err;
387
388         return 0;
389
390 err:
391         if (mm) {
392                 bprm->mm = NULL;
393                 mmdrop(mm);
394         }
395
396         return err;
397 }
398
399 struct user_arg_ptr {
400 #ifdef CONFIG_COMPAT
401         bool is_compat;
402 #endif
403         union {
404                 const char __user *const __user *native;
405 #ifdef CONFIG_COMPAT
406                 compat_uptr_t __user *compat;
407 #endif
408         } ptr;
409 };
410
411 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
412 {
413         const char __user *native;
414
415 #ifdef CONFIG_COMPAT
416         if (unlikely(argv.is_compat)) {
417                 compat_uptr_t compat;
418
419                 if (get_user(compat, argv.ptr.compat + nr))
420                         return ERR_PTR(-EFAULT);
421
422                 return compat_ptr(compat);
423         }
424 #endif
425
426         if (get_user(native, argv.ptr.native + nr))
427                 return ERR_PTR(-EFAULT);
428
429         return native;
430 }
431
432 /*
433  * count() counts the number of strings in array ARGV.
434  */
435 static int count(struct user_arg_ptr argv, int max)
436 {
437         int i = 0;
438
439         if (argv.ptr.native != NULL) {
440                 for (;;) {
441                         const char __user *p = get_user_arg_ptr(argv, i);
442
443                         if (!p)
444                                 break;
445
446                         if (IS_ERR(p))
447                                 return -EFAULT;
448
449                         if (i++ >= max)
450                                 return -E2BIG;
451
452                         if (fatal_signal_pending(current))
453                                 return -ERESTARTNOHAND;
454                         cond_resched();
455                 }
456         }
457         return i;
458 }
459
460 /*
461  * 'copy_strings()' copies argument/environment strings from the old
462  * processes's memory to the new process's stack.  The call to get_user_pages()
463  * ensures the destination page is created and not swapped out.
464  */
465 static int copy_strings(int argc, struct user_arg_ptr argv,
466                         struct linux_binprm *bprm)
467 {
468         struct page *kmapped_page = NULL;
469         char *kaddr = NULL;
470         unsigned long kpos = 0;
471         int ret;
472
473         while (argc-- > 0) {
474                 const char __user *str;
475                 int len;
476                 unsigned long pos;
477
478                 ret = -EFAULT;
479                 str = get_user_arg_ptr(argv, argc);
480                 if (IS_ERR(str))
481                         goto out;
482
483                 len = strnlen_user(str, MAX_ARG_STRLEN);
484                 if (!len)
485                         goto out;
486
487                 ret = -E2BIG;
488                 if (!valid_arg_len(bprm, len))
489                         goto out;
490
491                 /* We're going to work our way backwords. */
492                 pos = bprm->p;
493                 str += len;
494                 bprm->p -= len;
495
496                 while (len > 0) {
497                         int offset, bytes_to_copy;
498
499                         if (fatal_signal_pending(current)) {
500                                 ret = -ERESTARTNOHAND;
501                                 goto out;
502                         }
503                         cond_resched();
504
505                         offset = pos % PAGE_SIZE;
506                         if (offset == 0)
507                                 offset = PAGE_SIZE;
508
509                         bytes_to_copy = offset;
510                         if (bytes_to_copy > len)
511                                 bytes_to_copy = len;
512
513                         offset -= bytes_to_copy;
514                         pos -= bytes_to_copy;
515                         str -= bytes_to_copy;
516                         len -= bytes_to_copy;
517
518                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
519                                 struct page *page;
520
521                                 page = get_arg_page(bprm, pos, 1);
522                                 if (!page) {
523                                         ret = -E2BIG;
524                                         goto out;
525                                 }
526
527                                 if (kmapped_page) {
528                                         flush_kernel_dcache_page(kmapped_page);
529                                         kunmap(kmapped_page);
530                                         put_arg_page(kmapped_page);
531                                 }
532                                 kmapped_page = page;
533                                 kaddr = kmap(kmapped_page);
534                                 kpos = pos & PAGE_MASK;
535                                 flush_arg_page(bprm, kpos, kmapped_page);
536                         }
537                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
538                                 ret = -EFAULT;
539                                 goto out;
540                         }
541                 }
542         }
543         ret = 0;
544 out:
545         if (kmapped_page) {
546                 flush_kernel_dcache_page(kmapped_page);
547                 kunmap(kmapped_page);
548                 put_arg_page(kmapped_page);
549         }
550         return ret;
551 }
552
553 /*
554  * Like copy_strings, but get argv and its values from kernel memory.
555  */
556 int copy_strings_kernel(int argc, const char *const *__argv,
557                         struct linux_binprm *bprm)
558 {
559         int r;
560         mm_segment_t oldfs = get_fs();
561         struct user_arg_ptr argv = {
562                 .ptr.native = (const char __user *const  __user *)__argv,
563         };
564
565         set_fs(KERNEL_DS);
566         r = copy_strings(argc, argv, bprm);
567         set_fs(oldfs);
568
569         return r;
570 }
571 EXPORT_SYMBOL(copy_strings_kernel);
572
573 #ifdef CONFIG_MMU
574
575 /*
576  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
577  * the binfmt code determines where the new stack should reside, we shift it to
578  * its final location.  The process proceeds as follows:
579  *
580  * 1) Use shift to calculate the new vma endpoints.
581  * 2) Extend vma to cover both the old and new ranges.  This ensures the
582  *    arguments passed to subsequent functions are consistent.
583  * 3) Move vma's page tables to the new range.
584  * 4) Free up any cleared pgd range.
585  * 5) Shrink the vma to cover only the new range.
586  */
587 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
588 {
589         struct mm_struct *mm = vma->vm_mm;
590         unsigned long old_start = vma->vm_start;
591         unsigned long old_end = vma->vm_end;
592         unsigned long length = old_end - old_start;
593         unsigned long new_start = old_start - shift;
594         unsigned long new_end = old_end - shift;
595         struct mmu_gather tlb;
596
597         BUG_ON(new_start > new_end);
598
599         /*
600          * ensure there are no vmas between where we want to go
601          * and where we are
602          */
603         if (vma != find_vma(mm, new_start))
604                 return -EFAULT;
605
606         /*
607          * cover the whole range: [new_start, old_end)
608          */
609         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
610                 return -ENOMEM;
611
612         /*
613          * move the page tables downwards, on failure we rely on
614          * process cleanup to remove whatever mess we made.
615          */
616         if (length != move_page_tables(vma, old_start,
617                                        vma, new_start, length))
618                 return -ENOMEM;
619
620         lru_add_drain();
621         tlb_gather_mmu(&tlb, mm, 0);
622         if (new_end > old_start) {
623                 /*
624                  * when the old and new regions overlap clear from new_end.
625                  */
626                 free_pgd_range(&tlb, new_end, old_end, new_end,
627                         vma->vm_next ? vma->vm_next->vm_start : 0);
628         } else {
629                 /*
630                  * otherwise, clean from old_start; this is done to not touch
631                  * the address space in [new_end, old_start) some architectures
632                  * have constraints on va-space that make this illegal (IA64) -
633                  * for the others its just a little faster.
634                  */
635                 free_pgd_range(&tlb, old_start, old_end, new_end,
636                         vma->vm_next ? vma->vm_next->vm_start : 0);
637         }
638         tlb_finish_mmu(&tlb, new_end, old_end);
639
640         /*
641          * Shrink the vma to just the new range.  Always succeeds.
642          */
643         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
644
645         return 0;
646 }
647
648 /*
649  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
650  * the stack is optionally relocated, and some extra space is added.
651  */
652 int setup_arg_pages(struct linux_binprm *bprm,
653                     unsigned long stack_top,
654                     int executable_stack)
655 {
656         unsigned long ret;
657         unsigned long stack_shift;
658         struct mm_struct *mm = current->mm;
659         struct vm_area_struct *vma = bprm->vma;
660         struct vm_area_struct *prev = NULL;
661         unsigned long vm_flags;
662         unsigned long stack_base;
663         unsigned long stack_size;
664         unsigned long stack_expand;
665         unsigned long rlim_stack;
666
667 #ifdef CONFIG_STACK_GROWSUP
668         /* Limit stack size to 1GB */
669         stack_base = rlimit_max(RLIMIT_STACK);
670         if (stack_base > (1 << 30))
671                 stack_base = 1 << 30;
672
673         /* Make sure we didn't let the argument array grow too large. */
674         if (vma->vm_end - vma->vm_start > stack_base)
675                 return -ENOMEM;
676
677         stack_base = PAGE_ALIGN(stack_top - stack_base);
678
679         stack_shift = vma->vm_start - stack_base;
680         mm->arg_start = bprm->p - stack_shift;
681         bprm->p = vma->vm_end - stack_shift;
682 #else
683         stack_top = arch_align_stack(stack_top);
684         stack_top = PAGE_ALIGN(stack_top);
685
686         if (unlikely(stack_top < mmap_min_addr) ||
687             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
688                 return -ENOMEM;
689
690         stack_shift = vma->vm_end - stack_top;
691
692         bprm->p -= stack_shift;
693         mm->arg_start = bprm->p;
694 #endif
695
696         if (bprm->loader)
697                 bprm->loader -= stack_shift;
698         bprm->exec -= stack_shift;
699
700         down_write(&mm->mmap_sem);
701         vm_flags = VM_STACK_FLAGS;
702
703         /*
704          * Adjust stack execute permissions; explicitly enable for
705          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
706          * (arch default) otherwise.
707          */
708         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
709                 vm_flags |= VM_EXEC;
710         else if (executable_stack == EXSTACK_DISABLE_X)
711                 vm_flags &= ~VM_EXEC;
712         vm_flags |= mm->def_flags;
713         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
714
715         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
716                         vm_flags);
717         if (ret)
718                 goto out_unlock;
719         BUG_ON(prev != vma);
720
721         /* Move stack pages down in memory. */
722         if (stack_shift) {
723                 ret = shift_arg_pages(vma, stack_shift);
724                 if (ret)
725                         goto out_unlock;
726         }
727
728         /* mprotect_fixup is overkill to remove the temporary stack flags */
729         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
730
731         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
732         stack_size = vma->vm_end - vma->vm_start;
733         /*
734          * Align this down to a page boundary as expand_stack
735          * will align it up.
736          */
737         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
738 #ifdef CONFIG_STACK_GROWSUP
739         if (stack_size + stack_expand > rlim_stack)
740                 stack_base = vma->vm_start + rlim_stack;
741         else
742                 stack_base = vma->vm_end + stack_expand;
743 #else
744         if (stack_size + stack_expand > rlim_stack)
745                 stack_base = vma->vm_end - rlim_stack;
746         else
747                 stack_base = vma->vm_start - stack_expand;
748 #endif
749         current->mm->start_stack = bprm->p;
750         ret = expand_stack(vma, stack_base);
751         if (ret)
752                 ret = -EFAULT;
753
754 out_unlock:
755         up_write(&mm->mmap_sem);
756         return ret;
757 }
758 EXPORT_SYMBOL(setup_arg_pages);
759
760 #endif /* CONFIG_MMU */
761
762 struct file *open_exec(const char *name)
763 {
764         struct file *file;
765         int err;
766         static const struct open_flags open_exec_flags = {
767                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
768                 .acc_mode = MAY_EXEC | MAY_OPEN,
769                 .intent = LOOKUP_OPEN
770         };
771
772         file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
773         if (IS_ERR(file))
774                 goto out;
775
776         err = -EACCES;
777         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
778                 goto exit;
779
780         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
781                 goto exit;
782
783         fsnotify_open(file);
784
785         err = deny_write_access(file);
786         if (err)
787                 goto exit;
788
789 out:
790         return file;
791
792 exit:
793         fput(file);
794         return ERR_PTR(err);
795 }
796 EXPORT_SYMBOL(open_exec);
797
798 int kernel_read(struct file *file, loff_t offset,
799                 char *addr, unsigned long count)
800 {
801         mm_segment_t old_fs;
802         loff_t pos = offset;
803         int result;
804
805         old_fs = get_fs();
806         set_fs(get_ds());
807         /* The cast to a user pointer is valid due to the set_fs() */
808         result = vfs_read(file, (void __user *)addr, count, &pos);
809         set_fs(old_fs);
810         return result;
811 }
812
813 EXPORT_SYMBOL(kernel_read);
814
815 static int exec_mmap(struct mm_struct *mm)
816 {
817         struct task_struct *tsk;
818         struct mm_struct * old_mm, *active_mm;
819
820         /* Notify parent that we're no longer interested in the old VM */
821         tsk = current;
822         old_mm = current->mm;
823         sync_mm_rss(tsk, old_mm);
824         mm_release(tsk, old_mm);
825
826         if (old_mm) {
827                 /*
828                  * Make sure that if there is a core dump in progress
829                  * for the old mm, we get out and die instead of going
830                  * through with the exec.  We must hold mmap_sem around
831                  * checking core_state and changing tsk->mm.
832                  */
833                 down_read(&old_mm->mmap_sem);
834                 if (unlikely(old_mm->core_state)) {
835                         up_read(&old_mm->mmap_sem);
836                         return -EINTR;
837                 }
838         }
839         task_lock(tsk);
840         active_mm = tsk->active_mm;
841         tsk->mm = mm;
842         tsk->active_mm = mm;
843         activate_mm(active_mm, mm);
844         task_unlock(tsk);
845         arch_pick_mmap_layout(mm);
846         if (old_mm) {
847                 up_read(&old_mm->mmap_sem);
848                 BUG_ON(active_mm != 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_UNINTERRUPTIBLE);
892                 spin_unlock_irq(lock);
893                 schedule();
894                 spin_lock_irq(lock);
895         }
896         spin_unlock_irq(lock);
897
898         /*
899          * At this point all other threads have exited, all we have to
900          * do is to wait for the thread group leader to become inactive,
901          * and to assume its PID:
902          */
903         if (!thread_group_leader(tsk)) {
904                 struct task_struct *leader = tsk->group_leader;
905
906                 sig->notify_count = -1; /* for exit_notify() */
907                 for (;;) {
908                         write_lock_irq(&tasklist_lock);
909                         if (likely(leader->exit_state))
910                                 break;
911                         __set_current_state(TASK_UNINTERRUPTIBLE);
912                         write_unlock_irq(&tasklist_lock);
913                         schedule();
914                 }
915
916                 /*
917                  * The only record we have of the real-time age of a
918                  * process, regardless of execs it's done, is start_time.
919                  * All the past CPU time is accumulated in signal_struct
920                  * from sister threads now dead.  But in this non-leader
921                  * exec, nothing survives from the original leader thread,
922                  * whose birth marks the true age of this process now.
923                  * When we take on its identity by switching to its PID, we
924                  * also take its birthdate (always earlier than our own).
925                  */
926                 tsk->start_time = leader->start_time;
927
928                 BUG_ON(!same_thread_group(leader, tsk));
929                 BUG_ON(has_group_leader_pid(tsk));
930                 /*
931                  * An exec() starts a new thread group with the
932                  * TGID of the previous thread group. Rehash the
933                  * two threads with a switched PID, and release
934                  * the former thread group leader:
935                  */
936
937                 /* Become a process group leader with the old leader's pid.
938                  * The old leader becomes a thread of the this thread group.
939                  * Note: The old leader also uses this pid until release_task
940                  *       is called.  Odd but simple and correct.
941                  */
942                 detach_pid(tsk, PIDTYPE_PID);
943                 tsk->pid = leader->pid;
944                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
945                 transfer_pid(leader, tsk, PIDTYPE_PGID);
946                 transfer_pid(leader, tsk, PIDTYPE_SID);
947
948                 list_replace_rcu(&leader->tasks, &tsk->tasks);
949                 list_replace_init(&leader->sibling, &tsk->sibling);
950
951                 tsk->group_leader = tsk;
952                 leader->group_leader = tsk;
953
954                 tsk->exit_signal = SIGCHLD;
955                 leader->exit_signal = -1;
956
957                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
958                 leader->exit_state = EXIT_DEAD;
959
960                 /*
961                  * We are going to release_task()->ptrace_unlink() silently,
962                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
963                  * the tracer wont't block again waiting for this thread.
964                  */
965                 if (unlikely(leader->ptrace))
966                         __wake_up_parent(leader, leader->parent);
967                 write_unlock_irq(&tasklist_lock);
968
969                 release_task(leader);
970         }
971
972         sig->group_exit_task = NULL;
973         sig->notify_count = 0;
974
975 no_thread_group:
976         /* we have changed execution domain */
977         tsk->exit_signal = SIGCHLD;
978
979         if (current->mm)
980                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
981
982         exit_itimers(sig);
983         flush_itimer_signals();
984
985         if (atomic_read(&oldsighand->count) != 1) {
986                 struct sighand_struct *newsighand;
987                 /*
988                  * This ->sighand is shared with the CLONE_SIGHAND
989                  * but not CLONE_THREAD task, switch to the new one.
990                  */
991                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
992                 if (!newsighand)
993                         return -ENOMEM;
994
995                 atomic_set(&newsighand->count, 1);
996                 memcpy(newsighand->action, oldsighand->action,
997                        sizeof(newsighand->action));
998
999                 write_lock_irq(&tasklist_lock);
1000                 spin_lock(&oldsighand->siglock);
1001                 rcu_assign_pointer(tsk->sighand, newsighand);
1002                 spin_unlock(&oldsighand->siglock);
1003                 write_unlock_irq(&tasklist_lock);
1004
1005                 __cleanup_sighand(oldsighand);
1006         }
1007
1008         BUG_ON(!thread_group_leader(tsk));
1009         return 0;
1010 }
1011
1012 /*
1013  * These functions flushes out all traces of the currently running executable
1014  * so that a new one can be started
1015  */
1016 static void flush_old_files(struct files_struct * files)
1017 {
1018         long j = -1;
1019         struct fdtable *fdt;
1020
1021         spin_lock(&files->file_lock);
1022         for (;;) {
1023                 unsigned long set, i;
1024
1025                 j++;
1026                 i = j * __NFDBITS;
1027                 fdt = files_fdtable(files);
1028                 if (i >= fdt->max_fds)
1029                         break;
1030                 set = fdt->close_on_exec->fds_bits[j];
1031                 if (!set)
1032                         continue;
1033                 fdt->close_on_exec->fds_bits[j] = 0;
1034                 spin_unlock(&files->file_lock);
1035                 for ( ; set ; i++,set >>= 1) {
1036                         if (set & 1) {
1037                                 sys_close(i);
1038                         }
1039                 }
1040                 spin_lock(&files->file_lock);
1041
1042         }
1043         spin_unlock(&files->file_lock);
1044 }
1045
1046 char *get_task_comm(char *buf, struct task_struct *tsk)
1047 {
1048         /* buf must be at least sizeof(tsk->comm) in size */
1049         task_lock(tsk);
1050         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1051         task_unlock(tsk);
1052         return buf;
1053 }
1054 EXPORT_SYMBOL_GPL(get_task_comm);
1055
1056 void set_task_comm(struct task_struct *tsk, char *buf)
1057 {
1058         task_lock(tsk);
1059
1060         /*
1061          * Threads may access current->comm without holding
1062          * the task lock, so write the string carefully.
1063          * Readers without a lock may see incomplete new
1064          * names but are safe from non-terminating string reads.
1065          */
1066         memset(tsk->comm, 0, TASK_COMM_LEN);
1067         wmb();
1068         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1069         task_unlock(tsk);
1070         perf_event_comm(tsk);
1071 }
1072
1073 int flush_old_exec(struct linux_binprm * bprm)
1074 {
1075         int retval;
1076
1077         /*
1078          * Make sure we have a private signal table and that
1079          * we are unassociated from the previous thread group.
1080          */
1081         retval = de_thread(current);
1082         if (retval)
1083                 goto out;
1084
1085         set_mm_exe_file(bprm->mm, bprm->file);
1086
1087         /*
1088          * Release all of the old mmap stuff
1089          */
1090         acct_arg_size(bprm, 0);
1091         retval = exec_mmap(bprm->mm);
1092         if (retval)
1093                 goto out;
1094
1095         bprm->mm = NULL;                /* We're using it now */
1096
1097         set_fs(USER_DS);
1098         current->flags &=
1099                 ~(PF_RANDOMIZE | PF_KTHREAD | PF_NOFREEZE | PF_FREEZER_NOSIG);
1100         flush_thread();
1101         current->personality &= ~bprm->per_clear;
1102
1103         return 0;
1104
1105 out:
1106         return retval;
1107 }
1108 EXPORT_SYMBOL(flush_old_exec);
1109
1110 void would_dump(struct linux_binprm *bprm, struct file *file)
1111 {
1112         if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
1113                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1114 }
1115 EXPORT_SYMBOL(would_dump);
1116
1117 void setup_new_exec(struct linux_binprm * bprm)
1118 {
1119         int i, ch;
1120         const char *name;
1121         char tcomm[sizeof(current->comm)];
1122
1123         arch_pick_mmap_layout(current->mm);
1124
1125         /* This is the point of no return */
1126         current->sas_ss_sp = current->sas_ss_size = 0;
1127
1128         if (current_euid() == current_uid() && current_egid() == current_gid())
1129                 set_dumpable(current->mm, 1);
1130         else
1131                 set_dumpable(current->mm, suid_dumpable);
1132
1133         name = bprm->filename;
1134
1135         /* Copies the binary name from after last slash */
1136         for (i=0; (ch = *(name++)) != '\0';) {
1137                 if (ch == '/')
1138                         i = 0; /* overwrite what we wrote */
1139                 else
1140                         if (i < (sizeof(tcomm) - 1))
1141                                 tcomm[i++] = ch;
1142         }
1143         tcomm[i] = '\0';
1144         set_task_comm(current, tcomm);
1145
1146         /* Set the new mm task size. We have to do that late because it may
1147          * depend on TIF_32BIT which is only updated in flush_thread() on
1148          * some architectures like powerpc
1149          */
1150         current->mm->task_size = TASK_SIZE;
1151
1152         /* install the new credentials */
1153         if (bprm->cred->uid != current_euid() ||
1154             bprm->cred->gid != current_egid()) {
1155                 current->pdeath_signal = 0;
1156         } else {
1157                 would_dump(bprm, bprm->file);
1158                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159                         set_dumpable(current->mm, suid_dumpable);
1160         }
1161
1162         /* An exec changes our domain. We are no longer part of the thread
1163            group */
1164
1165         current->self_exec_id++;
1166                         
1167         flush_signal_handlers(current, 0);
1168         flush_old_files(current->files);
1169 }
1170 EXPORT_SYMBOL(setup_new_exec);
1171
1172 /*
1173  * Prepare credentials and lock ->cred_guard_mutex.
1174  * install_exec_creds() commits the new creds and drops the lock.
1175  * Or, if exec fails before, free_bprm() should release ->cred and
1176  * and unlock.
1177  */
1178 int prepare_bprm_creds(struct linux_binprm *bprm)
1179 {
1180         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1181                 return -ERESTARTNOINTR;
1182
1183         bprm->cred = prepare_exec_creds();
1184         if (likely(bprm->cred))
1185                 return 0;
1186
1187         mutex_unlock(&current->signal->cred_guard_mutex);
1188         return -ENOMEM;
1189 }
1190
1191 void free_bprm(struct linux_binprm *bprm)
1192 {
1193         free_arg_pages(bprm);
1194         if (bprm->cred) {
1195                 mutex_unlock(&current->signal->cred_guard_mutex);
1196                 abort_creds(bprm->cred);
1197         }
1198         /* If a binfmt changed the interp, free it. */
1199         if (bprm->interp != bprm->filename)
1200                 kfree(bprm->interp);
1201         kfree(bprm);
1202 }
1203
1204 int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1205 {
1206         /* If a binfmt changed the interp, free it first. */
1207         if (bprm->interp != bprm->filename)
1208                 kfree(bprm->interp);
1209         bprm->interp = kstrdup(interp, GFP_KERNEL);
1210         if (!bprm->interp)
1211                 return -ENOMEM;
1212         return 0;
1213 }
1214 EXPORT_SYMBOL(bprm_change_interp);
1215
1216 /*
1217  * install the new credentials for this executable
1218  */
1219 void install_exec_creds(struct linux_binprm *bprm)
1220 {
1221         security_bprm_committing_creds(bprm);
1222
1223         commit_creds(bprm->cred);
1224         bprm->cred = NULL;
1225
1226         /*
1227          * Disable monitoring for regular users
1228          * when executing setuid binaries. Must
1229          * wait until new credentials are committed
1230          * by commit_creds() above
1231          */
1232         if (get_dumpable(current->mm) != SUID_DUMP_USER)
1233                 perf_event_exit_task(current);
1234         /*
1235          * cred_guard_mutex must be held at least to this point to prevent
1236          * ptrace_attach() from altering our determination of the task's
1237          * credentials; any time after this it may be unlocked.
1238          */
1239         security_bprm_committed_creds(bprm);
1240         mutex_unlock(&current->signal->cred_guard_mutex);
1241 }
1242 EXPORT_SYMBOL(install_exec_creds);
1243
1244 /*
1245  * determine how safe it is to execute the proposed program
1246  * - the caller must hold ->cred_guard_mutex to protect against
1247  *   PTRACE_ATTACH
1248  */
1249 int check_unsafe_exec(struct linux_binprm *bprm)
1250 {
1251         struct task_struct *p = current, *t;
1252         unsigned n_fs;
1253         int res = 0;
1254
1255         if (p->ptrace) {
1256                 if (p->ptrace & PT_PTRACE_CAP)
1257                         bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1258                 else
1259                         bprm->unsafe |= LSM_UNSAFE_PTRACE;
1260         }
1261
1262         n_fs = 1;
1263         spin_lock(&p->fs->lock);
1264         rcu_read_lock();
1265         for (t = next_thread(p); t != p; t = next_thread(t)) {
1266                 if (t->fs == p->fs)
1267                         n_fs++;
1268         }
1269         rcu_read_unlock();
1270
1271         if (p->fs->users > n_fs) {
1272                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1273         } else {
1274                 res = -EAGAIN;
1275                 if (!p->fs->in_exec) {
1276                         p->fs->in_exec = 1;
1277                         res = 1;
1278                 }
1279         }
1280         spin_unlock(&p->fs->lock);
1281
1282         return res;
1283 }
1284
1285 static void bprm_fill_uid(struct linux_binprm *bprm)
1286 {
1287         struct inode *inode;
1288         unsigned int mode;
1289         uid_t uid;
1290         gid_t gid;
1291
1292         /* clear any previous set[ug]id data from a previous binary */
1293         bprm->cred->euid = current_euid();
1294         bprm->cred->egid = current_egid();
1295
1296         if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
1297                 return;
1298
1299         inode = bprm->file->f_path.dentry->d_inode;
1300         mode = ACCESS_ONCE(inode->i_mode);
1301         if (!(mode & (S_ISUID|S_ISGID)))
1302                 return;
1303
1304         /* Be careful if suid/sgid is set */
1305         mutex_lock(&inode->i_mutex);
1306
1307         /* reload atomically mode/uid/gid now that lock held */
1308         mode = inode->i_mode;
1309         uid = inode->i_uid;
1310         gid = inode->i_gid;
1311         mutex_unlock(&inode->i_mutex);
1312
1313         if (mode & S_ISUID) {
1314                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1315                 bprm->cred->euid = uid;
1316         }
1317
1318         if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1319                 bprm->per_clear |= PER_CLEAR_ON_SETID;
1320                 bprm->cred->egid = gid;
1321         }
1322 }
1323
1324 /* 
1325  * Fill the binprm structure from the inode. 
1326  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1327  *
1328  * This may be called multiple times for binary chains (scripts for example).
1329  */
1330 int prepare_binprm(struct linux_binprm *bprm)
1331 {
1332         int retval;
1333
1334         if (bprm->file->f_op == NULL)
1335                 return -EACCES;
1336
1337         bprm_fill_uid(bprm);
1338
1339         /* fill in binprm security blob */
1340         retval = security_bprm_set_creds(bprm);
1341         if (retval)
1342                 return retval;
1343         bprm->cred_prepared = 1;
1344
1345         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1346         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1347 }
1348
1349 EXPORT_SYMBOL(prepare_binprm);
1350
1351 /*
1352  * Arguments are '\0' separated strings found at the location bprm->p
1353  * points to; chop off the first by relocating brpm->p to right after
1354  * the first '\0' encountered.
1355  */
1356 int remove_arg_zero(struct linux_binprm *bprm)
1357 {
1358         int ret = 0;
1359         unsigned long offset;
1360         char *kaddr;
1361         struct page *page;
1362
1363         if (!bprm->argc)
1364                 return 0;
1365
1366         do {
1367                 offset = bprm->p & ~PAGE_MASK;
1368                 page = get_arg_page(bprm, bprm->p, 0);
1369                 if (!page) {
1370                         ret = -EFAULT;
1371                         goto out;
1372                 }
1373                 kaddr = kmap_atomic(page, KM_USER0);
1374
1375                 for (; offset < PAGE_SIZE && kaddr[offset];
1376                                 offset++, bprm->p++)
1377                         ;
1378
1379                 kunmap_atomic(kaddr, KM_USER0);
1380                 put_arg_page(page);
1381
1382                 if (offset == PAGE_SIZE)
1383                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1384         } while (offset == PAGE_SIZE);
1385
1386         bprm->p++;
1387         bprm->argc--;
1388         ret = 0;
1389
1390 out:
1391         return ret;
1392 }
1393 EXPORT_SYMBOL(remove_arg_zero);
1394
1395 /*
1396  * cycle the list of binary formats handler, until one recognizes the image
1397  */
1398 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1399 {
1400         unsigned int depth = bprm->recursion_depth;
1401         int try,retval;
1402         struct linux_binfmt *fmt;
1403         pid_t old_pid;
1404
1405         /* This allows 4 levels of binfmt rewrites before failing hard. */
1406         if (depth > 5)
1407                 return -ELOOP;
1408
1409         retval = security_bprm_check(bprm);
1410         if (retval)
1411                 return retval;
1412
1413         retval = audit_bprm(bprm);
1414         if (retval)
1415                 return retval;
1416
1417         /* Need to fetch pid before load_binary changes it */
1418         rcu_read_lock();
1419         old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1420         rcu_read_unlock();
1421
1422         retval = -ENOENT;
1423         for (try=0; try<2; try++) {
1424                 read_lock(&binfmt_lock);
1425                 list_for_each_entry(fmt, &formats, lh) {
1426                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1427                         if (!fn)
1428                                 continue;
1429                         if (!try_module_get(fmt->module))
1430                                 continue;
1431                         read_unlock(&binfmt_lock);
1432                         bprm->recursion_depth = depth + 1;
1433                         retval = fn(bprm, regs);
1434                         bprm->recursion_depth = depth;
1435                         if (retval >= 0) {
1436                                 if (depth == 0)
1437                                         ptrace_event(PTRACE_EVENT_EXEC,
1438                                                         old_pid);
1439                                 put_binfmt(fmt);
1440                                 allow_write_access(bprm->file);
1441                                 if (bprm->file)
1442                                         fput(bprm->file);
1443                                 bprm->file = NULL;
1444                                 current->did_exec = 1;
1445                                 proc_exec_connector(current);
1446                                 return retval;
1447                         }
1448                         read_lock(&binfmt_lock);
1449                         put_binfmt(fmt);
1450                         if (retval != -ENOEXEC || bprm->mm == NULL)
1451                                 break;
1452                         if (!bprm->file) {
1453                                 read_unlock(&binfmt_lock);
1454                                 return retval;
1455                         }
1456                 }
1457                 read_unlock(&binfmt_lock);
1458 #ifdef CONFIG_MODULES
1459                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1460                         break;
1461                 } else {
1462 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1463                         if (printable(bprm->buf[0]) &&
1464                             printable(bprm->buf[1]) &&
1465                             printable(bprm->buf[2]) &&
1466                             printable(bprm->buf[3]))
1467                                 break; /* -ENOEXEC */
1468                         if (try)
1469                                 break; /* -ENOEXEC */
1470                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1471                 }
1472 #else
1473                 break;
1474 #endif
1475         }
1476         return retval;
1477 }
1478
1479 EXPORT_SYMBOL(search_binary_handler);
1480
1481 /*
1482  * sys_execve() executes a new program.
1483  */
1484 static int do_execve_common(const char *filename,
1485                                 struct user_arg_ptr argv,
1486                                 struct user_arg_ptr envp,
1487                                 struct pt_regs *regs)
1488 {
1489         struct linux_binprm *bprm;
1490         struct file *file;
1491         struct files_struct *displaced;
1492         bool clear_in_exec;
1493         int retval;
1494         const struct cred *cred = current_cred();
1495
1496         /*
1497          * We move the actual failure in case of RLIMIT_NPROC excess from
1498          * set*uid() to execve() because too many poorly written programs
1499          * don't check setuid() return code.  Here we additionally recheck
1500          * whether NPROC limit is still exceeded.
1501          */
1502         if ((current->flags & PF_NPROC_EXCEEDED) &&
1503             atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1504                 retval = -EAGAIN;
1505                 goto out_ret;
1506         }
1507
1508         /* We're below the limit (still or again), so we don't want to make
1509          * further execve() calls fail. */
1510         current->flags &= ~PF_NPROC_EXCEEDED;
1511
1512         retval = unshare_files(&displaced);
1513         if (retval)
1514                 goto out_ret;
1515
1516         retval = -ENOMEM;
1517         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1518         if (!bprm)
1519                 goto out_files;
1520
1521         retval = prepare_bprm_creds(bprm);
1522         if (retval)
1523                 goto out_free;
1524
1525         retval = check_unsafe_exec(bprm);
1526         if (retval < 0)
1527                 goto out_free;
1528         clear_in_exec = retval;
1529         current->in_execve = 1;
1530
1531         file = open_exec(filename);
1532         retval = PTR_ERR(file);
1533         if (IS_ERR(file))
1534                 goto out_unmark;
1535
1536         sched_exec();
1537
1538         bprm->file = file;
1539         bprm->filename = filename;
1540         bprm->interp = filename;
1541
1542         retval = bprm_mm_init(bprm);
1543         if (retval)
1544                 goto out_file;
1545
1546         bprm->argc = count(argv, MAX_ARG_STRINGS);
1547         if ((retval = bprm->argc) < 0)
1548                 goto out;
1549
1550         bprm->envc = count(envp, MAX_ARG_STRINGS);
1551         if ((retval = bprm->envc) < 0)
1552                 goto out;
1553
1554         retval = prepare_binprm(bprm);
1555         if (retval < 0)
1556                 goto out;
1557
1558         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1559         if (retval < 0)
1560                 goto out;
1561
1562         bprm->exec = bprm->p;
1563         retval = copy_strings(bprm->envc, envp, bprm);
1564         if (retval < 0)
1565                 goto out;
1566
1567         retval = copy_strings(bprm->argc, argv, bprm);
1568         if (retval < 0)
1569                 goto out;
1570
1571         retval = search_binary_handler(bprm,regs);
1572         if (retval < 0)
1573                 goto out;
1574
1575         /* execve succeeded */
1576         current->fs->in_exec = 0;
1577         current->in_execve = 0;
1578         acct_update_integrals(current);
1579         free_bprm(bprm);
1580         if (displaced)
1581                 put_files_struct(displaced);
1582         return retval;
1583
1584 out:
1585         if (bprm->mm) {
1586                 acct_arg_size(bprm, 0);
1587                 mmput(bprm->mm);
1588         }
1589
1590 out_file:
1591         if (bprm->file) {
1592                 allow_write_access(bprm->file);
1593                 fput(bprm->file);
1594         }
1595
1596 out_unmark:
1597         if (clear_in_exec)
1598                 current->fs->in_exec = 0;
1599         current->in_execve = 0;
1600
1601 out_free:
1602         free_bprm(bprm);
1603
1604 out_files:
1605         if (displaced)
1606                 reset_files_struct(displaced);
1607 out_ret:
1608         return retval;
1609 }
1610
1611 int do_execve(const char *filename,
1612         const char __user *const __user *__argv,
1613         const char __user *const __user *__envp,
1614         struct pt_regs *regs)
1615 {
1616         struct user_arg_ptr argv = { .ptr.native = __argv };
1617         struct user_arg_ptr envp = { .ptr.native = __envp };
1618         return do_execve_common(filename, argv, envp, regs);
1619 }
1620
1621 #ifdef CONFIG_COMPAT
1622 int compat_do_execve(char *filename,
1623         compat_uptr_t __user *__argv,
1624         compat_uptr_t __user *__envp,
1625         struct pt_regs *regs)
1626 {
1627         struct user_arg_ptr argv = {
1628                 .is_compat = true,
1629                 .ptr.compat = __argv,
1630         };
1631         struct user_arg_ptr envp = {
1632                 .is_compat = true,
1633                 .ptr.compat = __envp,
1634         };
1635         return do_execve_common(filename, argv, envp, regs);
1636 }
1637 #endif
1638
1639 void set_binfmt(struct linux_binfmt *new)
1640 {
1641         struct mm_struct *mm = current->mm;
1642
1643         if (mm->binfmt)
1644                 module_put(mm->binfmt->module);
1645
1646         mm->binfmt = new;
1647         if (new)
1648                 __module_get(new->module);
1649 }
1650
1651 EXPORT_SYMBOL(set_binfmt);
1652
1653 static int expand_corename(struct core_name *cn)
1654 {
1655         char *old_corename = cn->corename;
1656
1657         cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1658         cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1659
1660         if (!cn->corename) {
1661                 kfree(old_corename);
1662                 return -ENOMEM;
1663         }
1664
1665         return 0;
1666 }
1667
1668 static int cn_printf(struct core_name *cn, const char *fmt, ...)
1669 {
1670         char *cur;
1671         int need;
1672         int ret;
1673         va_list arg;
1674
1675         va_start(arg, fmt);
1676         need = vsnprintf(NULL, 0, fmt, arg);
1677         va_end(arg);
1678
1679         if (likely(need < cn->size - cn->used - 1))
1680                 goto out_printf;
1681
1682         ret = expand_corename(cn);
1683         if (ret)
1684                 goto expand_fail;
1685
1686 out_printf:
1687         cur = cn->corename + cn->used;
1688         va_start(arg, fmt);
1689         vsnprintf(cur, need + 1, fmt, arg);
1690         va_end(arg);
1691         cn->used += need;
1692         return 0;
1693
1694 expand_fail:
1695         return ret;
1696 }
1697
1698 static void cn_escape(char *str)
1699 {
1700         for (; *str; str++)
1701                 if (*str == '/')
1702                         *str = '!';
1703 }
1704
1705 static int cn_print_exe_file(struct core_name *cn)
1706 {
1707         struct file *exe_file;
1708         char *pathbuf, *path;
1709         int ret;
1710
1711         exe_file = get_mm_exe_file(current->mm);
1712         if (!exe_file) {
1713                 char *commstart = cn->corename + cn->used;
1714                 ret = cn_printf(cn, "%s (path unknown)", current->comm);
1715                 cn_escape(commstart);
1716                 return ret;
1717         }
1718
1719         pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1720         if (!pathbuf) {
1721                 ret = -ENOMEM;
1722                 goto put_exe_file;
1723         }
1724
1725         path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1726         if (IS_ERR(path)) {
1727                 ret = PTR_ERR(path);
1728                 goto free_buf;
1729         }
1730
1731         cn_escape(path);
1732
1733         ret = cn_printf(cn, "%s", path);
1734
1735 free_buf:
1736         kfree(pathbuf);
1737 put_exe_file:
1738         fput(exe_file);
1739         return ret;
1740 }
1741
1742 /* format_corename will inspect the pattern parameter, and output a
1743  * name into corename, which must have space for at least
1744  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1745  */
1746 static int format_corename(struct core_name *cn, long signr)
1747 {
1748         const struct cred *cred = current_cred();
1749         const char *pat_ptr = core_pattern;
1750         int ispipe = (*pat_ptr == '|');
1751         int pid_in_pattern = 0;
1752         int err = 0;
1753
1754         cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1755         cn->corename = kmalloc(cn->size, GFP_KERNEL);
1756         cn->used = 0;
1757
1758         if (!cn->corename)
1759                 return -ENOMEM;
1760
1761         /* Repeat as long as we have more pattern to process and more output
1762            space */
1763         while (*pat_ptr) {
1764                 if (*pat_ptr != '%') {
1765                         if (*pat_ptr == 0)
1766                                 goto out;
1767                         err = cn_printf(cn, "%c", *pat_ptr++);
1768                 } else {
1769                         switch (*++pat_ptr) {
1770                         /* single % at the end, drop that */
1771                         case 0:
1772                                 goto out;
1773                         /* Double percent, output one percent */
1774                         case '%':
1775                                 err = cn_printf(cn, "%c", '%');
1776                                 break;
1777                         /* pid */
1778                         case 'p':
1779                                 pid_in_pattern = 1;
1780                                 err = cn_printf(cn, "%d",
1781                                               task_tgid_vnr(current));
1782                                 break;
1783                         /* uid */
1784                         case 'u':
1785                                 err = cn_printf(cn, "%d", cred->uid);
1786                                 break;
1787                         /* gid */
1788                         case 'g':
1789                                 err = cn_printf(cn, "%d", cred->gid);
1790                                 break;
1791                         /* signal that caused the coredump */
1792                         case 's':
1793                                 err = cn_printf(cn, "%ld", signr);
1794                                 break;
1795                         /* UNIX time of coredump */
1796                         case 't': {
1797                                 struct timeval tv;
1798                                 do_gettimeofday(&tv);
1799                                 err = cn_printf(cn, "%lu", tv.tv_sec);
1800                                 break;
1801                         }
1802                         /* hostname */
1803                         case 'h': {
1804                                 char *namestart = cn->corename + cn->used;
1805                                 down_read(&uts_sem);
1806                                 err = cn_printf(cn, "%s",
1807                                               utsname()->nodename);
1808                                 up_read(&uts_sem);
1809                                 cn_escape(namestart);
1810                                 break;
1811                         }
1812                         /* executable */
1813                         case 'e': {
1814                                 char *commstart = cn->corename + cn->used;
1815                                 err = cn_printf(cn, "%s", current->comm);
1816                                 cn_escape(commstart);
1817                                 break;
1818                         }
1819                         case 'E':
1820                                 err = cn_print_exe_file(cn);
1821                                 break;
1822                         /* core limit size */
1823                         case 'c':
1824                                 err = cn_printf(cn, "%lu",
1825                                               rlimit(RLIMIT_CORE));
1826                                 break;
1827                         default:
1828                                 break;
1829                         }
1830                         ++pat_ptr;
1831                 }
1832
1833                 if (err)
1834                         return err;
1835         }
1836
1837         /* Backward compatibility with core_uses_pid:
1838          *
1839          * If core_pattern does not include a %p (as is the default)
1840          * and core_uses_pid is set, then .%pid will be appended to
1841          * the filename. Do not do this for piped commands. */
1842         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1843                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1844                 if (err)
1845                         return err;
1846         }
1847 out:
1848         return ispipe;
1849 }
1850
1851 static int zap_process(struct task_struct *start, int exit_code)
1852 {
1853         struct task_struct *t;
1854         int nr = 0;
1855
1856         start->signal->flags = SIGNAL_GROUP_EXIT;
1857         start->signal->group_exit_code = exit_code;
1858         start->signal->group_stop_count = 0;
1859
1860         t = start;
1861         do {
1862                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1863                 if (t != current && t->mm) {
1864                         sigaddset(&t->pending.signal, SIGKILL);
1865                         signal_wake_up(t, 1);
1866                         nr++;
1867                 }
1868         } while_each_thread(start, t);
1869
1870         return nr;
1871 }
1872
1873 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1874                                 struct core_state *core_state, int exit_code)
1875 {
1876         struct task_struct *g, *p;
1877         unsigned long flags;
1878         int nr = -EAGAIN;
1879
1880         spin_lock_irq(&tsk->sighand->siglock);
1881         if (!signal_group_exit(tsk->signal)) {
1882                 mm->core_state = core_state;
1883                 nr = zap_process(tsk, exit_code);
1884         }
1885         spin_unlock_irq(&tsk->sighand->siglock);
1886         if (unlikely(nr < 0))
1887                 return nr;
1888
1889         if (atomic_read(&mm->mm_users) == nr + 1)
1890                 goto done;
1891         /*
1892          * We should find and kill all tasks which use this mm, and we should
1893          * count them correctly into ->nr_threads. We don't take tasklist
1894          * lock, but this is safe wrt:
1895          *
1896          * fork:
1897          *      None of sub-threads can fork after zap_process(leader). All
1898          *      processes which were created before this point should be
1899          *      visible to zap_threads() because copy_process() adds the new
1900          *      process to the tail of init_task.tasks list, and lock/unlock
1901          *      of ->siglock provides a memory barrier.
1902          *
1903          * do_exit:
1904          *      The caller holds mm->mmap_sem. This means that the task which
1905          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1906          *      its ->mm.
1907          *
1908          * de_thread:
1909          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1910          *      we must see either old or new leader, this does not matter.
1911          *      However, it can change p->sighand, so lock_task_sighand(p)
1912          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1913          *      it can't fail.
1914          *
1915          *      Note also that "g" can be the old leader with ->mm == NULL
1916          *      and already unhashed and thus removed from ->thread_group.
1917          *      This is OK, __unhash_process()->list_del_rcu() does not
1918          *      clear the ->next pointer, we will find the new leader via
1919          *      next_thread().
1920          */
1921         rcu_read_lock();
1922         for_each_process(g) {
1923                 if (g == tsk->group_leader)
1924                         continue;
1925                 if (g->flags & PF_KTHREAD)
1926                         continue;
1927                 p = g;
1928                 do {
1929                         if (p->mm) {
1930                                 if (unlikely(p->mm == mm)) {
1931                                         lock_task_sighand(p, &flags);
1932                                         nr += zap_process(p, exit_code);
1933                                         unlock_task_sighand(p, &flags);
1934                                 }
1935                                 break;
1936                         }
1937                 } while_each_thread(g, p);
1938         }
1939         rcu_read_unlock();
1940 done:
1941         atomic_set(&core_state->nr_threads, nr);
1942         return nr;
1943 }
1944
1945 static int coredump_wait(int exit_code, struct core_state *core_state)
1946 {
1947         struct task_struct *tsk = current;
1948         struct mm_struct *mm = tsk->mm;
1949         struct completion *vfork_done;
1950         int core_waiters = -EBUSY;
1951
1952         init_completion(&core_state->startup);
1953         core_state->dumper.task = tsk;
1954         core_state->dumper.next = NULL;
1955
1956         down_write(&mm->mmap_sem);
1957         if (!mm->core_state)
1958                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1959         up_write(&mm->mmap_sem);
1960
1961         if (unlikely(core_waiters < 0))
1962                 goto fail;
1963
1964         /*
1965          * Make sure nobody is waiting for us to release the VM,
1966          * otherwise we can deadlock when we wait on each other
1967          */
1968         vfork_done = tsk->vfork_done;
1969         if (vfork_done) {
1970                 tsk->vfork_done = NULL;
1971                 complete(vfork_done);
1972         }
1973
1974         if (core_waiters)
1975                 wait_for_completion(&core_state->startup);
1976 fail:
1977         return core_waiters;
1978 }
1979
1980 static void coredump_finish(struct mm_struct *mm)
1981 {
1982         struct core_thread *curr, *next;
1983         struct task_struct *task;
1984
1985         next = mm->core_state->dumper.next;
1986         while ((curr = next) != NULL) {
1987                 next = curr->next;
1988                 task = curr->task;
1989                 /*
1990                  * see exit_mm(), curr->task must not see
1991                  * ->task == NULL before we read ->next.
1992                  */
1993                 smp_mb();
1994                 curr->task = NULL;
1995                 wake_up_process(task);
1996         }
1997
1998         mm->core_state = NULL;
1999 }
2000
2001 /*
2002  * set_dumpable converts traditional three-value dumpable to two flags and
2003  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
2004  * these bits are not changed atomically.  So get_dumpable can observe the
2005  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
2006  * return either old dumpable or new one by paying attention to the order of
2007  * modifying the bits.
2008  *
2009  * dumpable |   mm->flags (binary)
2010  * old  new | initial interim  final
2011  * ---------+-----------------------
2012  *  0    1  |   00      01      01
2013  *  0    2  |   00      10(*)   11
2014  *  1    0  |   01      00      00
2015  *  1    2  |   01      11      11
2016  *  2    0  |   11      10(*)   00
2017  *  2    1  |   11      11      01
2018  *
2019  * (*) get_dumpable regards interim value of 10 as 11.
2020  */
2021 void set_dumpable(struct mm_struct *mm, int value)
2022 {
2023         switch (value) {
2024         case 0:
2025                 clear_bit(MMF_DUMPABLE, &mm->flags);
2026                 smp_wmb();
2027                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2028                 break;
2029         case 1:
2030                 set_bit(MMF_DUMPABLE, &mm->flags);
2031                 smp_wmb();
2032                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2033                 break;
2034         case 2:
2035                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
2036                 smp_wmb();
2037                 set_bit(MMF_DUMPABLE, &mm->flags);
2038                 break;
2039         }
2040 }
2041
2042 static int __get_dumpable(unsigned long mm_flags)
2043 {
2044         int ret;
2045
2046         ret = mm_flags & MMF_DUMPABLE_MASK;
2047         return (ret >= 2) ? 2 : ret;
2048 }
2049
2050 /*
2051  * This returns the actual value of the suid_dumpable flag. For things
2052  * that are using this for checking for privilege transitions, it must
2053  * test against SUID_DUMP_USER rather than treating it as a boolean
2054  * value.
2055  */
2056 int get_dumpable(struct mm_struct *mm)
2057 {
2058         return __get_dumpable(mm->flags);
2059 }
2060
2061 static void wait_for_dump_helpers(struct file *file)
2062 {
2063         struct pipe_inode_info *pipe;
2064
2065         pipe = file->f_path.dentry->d_inode->i_pipe;
2066
2067         pipe_lock(pipe);
2068         pipe->readers++;
2069         pipe->writers--;
2070
2071         while ((pipe->readers > 1) && (!signal_pending(current))) {
2072                 wake_up_interruptible_sync(&pipe->wait);
2073                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2074                 pipe_wait(pipe);
2075         }
2076
2077         pipe->readers--;
2078         pipe->writers++;
2079         pipe_unlock(pipe);
2080
2081 }
2082
2083
2084 /*
2085  * umh_pipe_setup
2086  * helper function to customize the process used
2087  * to collect the core in userspace.  Specifically
2088  * it sets up a pipe and installs it as fd 0 (stdin)
2089  * for the process.  Returns 0 on success, or
2090  * PTR_ERR on failure.
2091  * Note that it also sets the core limit to 1.  This
2092  * is a special value that we use to trap recursive
2093  * core dumps
2094  */
2095 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2096 {
2097         struct file *rp, *wp;
2098         struct fdtable *fdt;
2099         struct coredump_params *cp = (struct coredump_params *)info->data;
2100         struct files_struct *cf = current->files;
2101
2102         wp = create_write_pipe(0);
2103         if (IS_ERR(wp))
2104                 return PTR_ERR(wp);
2105
2106         rp = create_read_pipe(wp, 0);
2107         if (IS_ERR(rp)) {
2108                 free_write_pipe(wp);
2109                 return PTR_ERR(rp);
2110         }
2111
2112         cp->file = wp;
2113
2114         sys_close(0);
2115         fd_install(0, rp);
2116         spin_lock(&cf->file_lock);
2117         fdt = files_fdtable(cf);
2118         FD_SET(0, fdt->open_fds);
2119         FD_CLR(0, fdt->close_on_exec);
2120         spin_unlock(&cf->file_lock);
2121
2122         /* and disallow core files too */
2123         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2124
2125         return 0;
2126 }
2127
2128 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2129 {
2130         struct core_state core_state;
2131         struct core_name cn;
2132         struct mm_struct *mm = current->mm;
2133         struct linux_binfmt * binfmt;
2134         const struct cred *old_cred;
2135         struct cred *cred;
2136         int retval = 0;
2137         int ispipe;
2138         /* require nonrelative corefile path and be extra careful */
2139         bool need_suid_safe = false;
2140         static atomic_t core_dump_count = ATOMIC_INIT(0);
2141         struct coredump_params cprm = {
2142                 .signr = signr,
2143                 .regs = regs,
2144                 .limit = rlimit(RLIMIT_CORE),
2145                 /*
2146                  * We must use the same mm->flags while dumping core to avoid
2147                  * inconsistency of bit flags, since this flag is not protected
2148                  * by any locks.
2149                  */
2150                 .mm_flags = mm->flags,
2151         };
2152
2153         audit_core_dumps(signr);
2154
2155         binfmt = mm->binfmt;
2156         if (!binfmt || !binfmt->core_dump)
2157                 goto fail;
2158         if (!__get_dumpable(cprm.mm_flags))
2159                 goto fail;
2160
2161         cred = prepare_creds();
2162         if (!cred)
2163                 goto fail;
2164         /*
2165          * We cannot trust fsuid as being the "true" uid of the process
2166          * nor do we know its entire history. We only know it was tainted
2167          * so we dump it as root in mode 2, and only into a controlled
2168          * environment (pipe handler or fully qualified path).
2169          */
2170         if (__get_dumpable(cprm.mm_flags) == 2) {
2171                 /* Setuid core dump mode */
2172                 cred->fsuid = 0;        /* Dump root private */
2173                 need_suid_safe = true;
2174         }
2175
2176         retval = coredump_wait(exit_code, &core_state);
2177         if (retval < 0)
2178                 goto fail_creds;
2179
2180         old_cred = override_creds(cred);
2181
2182         /*
2183          * Clear any false indication of pending signals that might
2184          * be seen by the filesystem code called to write the core file.
2185          */
2186         clear_thread_flag(TIF_SIGPENDING);
2187
2188         ispipe = format_corename(&cn, signr);
2189
2190         if (ispipe) {
2191                 int dump_count;
2192                 char **helper_argv;
2193
2194                 if (ispipe < 0) {
2195                         printk(KERN_WARNING "format_corename failed\n");
2196                         printk(KERN_WARNING "Aborting core\n");
2197                         goto fail_corename;
2198                 }
2199
2200                 if (cprm.limit == 1) {
2201                         /*
2202                          * Normally core limits are irrelevant to pipes, since
2203                          * we're not writing to the file system, but we use
2204                          * cprm.limit of 1 here as a speacial value. Any
2205                          * non-1 limit gets set to RLIM_INFINITY below, but
2206                          * a limit of 0 skips the dump.  This is a consistent
2207                          * way to catch recursive crashes.  We can still crash
2208                          * if the core_pattern binary sets RLIM_CORE =  !1
2209                          * but it runs as root, and can do lots of stupid things
2210                          * Note that we use task_tgid_vnr here to grab the pid
2211                          * of the process group leader.  That way we get the
2212                          * right pid if a thread in a multi-threaded
2213                          * core_pattern process dies.
2214                          */
2215                         printk(KERN_WARNING
2216                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2217                                 task_tgid_vnr(current), current->comm);
2218                         printk(KERN_WARNING "Aborting core\n");
2219                         goto fail_unlock;
2220                 }
2221                 cprm.limit = RLIM_INFINITY;
2222
2223                 dump_count = atomic_inc_return(&core_dump_count);
2224                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2225                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2226                                task_tgid_vnr(current), current->comm);
2227                         printk(KERN_WARNING "Skipping core dump\n");
2228                         goto fail_dropcount;
2229                 }
2230
2231                 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2232                 if (!helper_argv) {
2233                         printk(KERN_WARNING "%s failed to allocate memory\n",
2234                                __func__);
2235                         goto fail_dropcount;
2236                 }
2237
2238                 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2239                                         NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2240                                         NULL, &cprm);
2241                 argv_free(helper_argv);
2242                 if (retval) {
2243                         printk(KERN_INFO "Core dump to %s pipe failed\n",
2244                                cn.corename);
2245                         goto close_fail;
2246                 }
2247         } else {
2248                 struct inode *inode;
2249
2250                 if (cprm.limit < binfmt->min_coredump)
2251                         goto fail_unlock;
2252
2253                 if (need_suid_safe && cn.corename[0] != '/') {
2254                         printk(KERN_WARNING "Pid %d(%s) can only dump core "\
2255                                 "to fully qualified path!\n",
2256                                 task_tgid_vnr(current), current->comm);
2257                         printk(KERN_WARNING "Skipping core dump\n");
2258                         goto fail_unlock;
2259                 }
2260
2261                 /*
2262                  * Unlink the file if it exists unless this is a SUID
2263                  * binary - in that case, we're running around with root
2264                  * privs and don't want to unlink another user's coredump.
2265                  */
2266                 if (!need_suid_safe) {
2267                         mm_segment_t old_fs;
2268
2269                         old_fs = get_fs();
2270                         set_fs(KERNEL_DS);
2271                         /*
2272                          * If it doesn't exist, that's fine. If there's some
2273                          * other problem, we'll catch it at the filp_open().
2274                          */
2275                         (void) sys_unlink((const char __user *)cn.corename);
2276                         set_fs(old_fs);
2277                 }
2278
2279                 /*
2280                  * There is a race between unlinking and creating the
2281                  * file, but if that causes an EEXIST here, that's
2282                  * fine - another process raced with us while creating
2283                  * the corefile, and the other process won. To userspace,
2284                  * what matters is that at least one of the two processes
2285                  * writes its coredump successfully, not which one.
2286                  */
2287                 cprm.file = filp_open(cn.corename,
2288                                  O_CREAT | 2 | O_NOFOLLOW |
2289                                  O_LARGEFILE | O_EXCL,
2290                                  0600);
2291                 if (IS_ERR(cprm.file))
2292                         goto fail_unlock;
2293
2294                 inode = cprm.file->f_path.dentry->d_inode;
2295                 if (inode->i_nlink > 1)
2296                         goto close_fail;
2297                 if (d_unhashed(cprm.file->f_path.dentry))
2298                         goto close_fail;
2299                 /*
2300                  * AK: actually i see no reason to not allow this for named
2301                  * pipes etc, but keep the previous behaviour for now.
2302                  */
2303                 if (!S_ISREG(inode->i_mode))
2304                         goto close_fail;
2305                 /*
2306                  * Dont allow local users get cute and trick others to coredump
2307                  * into their pre-created files.
2308                  */
2309                 if (inode->i_uid != current_fsuid())
2310                         goto close_fail;
2311                 if (!cprm.file->f_op || !cprm.file->f_op->write)
2312                         goto close_fail;
2313                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2314                         goto close_fail;
2315         }
2316
2317         retval = binfmt->core_dump(&cprm);
2318         if (retval)
2319                 current->signal->group_exit_code |= 0x80;
2320
2321         if (ispipe && core_pipe_limit)
2322                 wait_for_dump_helpers(cprm.file);
2323 close_fail:
2324         if (cprm.file)
2325                 filp_close(cprm.file, NULL);
2326 fail_dropcount:
2327         if (ispipe)
2328                 atomic_dec(&core_dump_count);
2329 fail_unlock:
2330         kfree(cn.corename);
2331 fail_corename:
2332         coredump_finish(mm);
2333         revert_creds(old_cred);
2334 fail_creds:
2335         put_cred(cred);
2336 fail:
2337         return;
2338 }
2339
2340 /*
2341  * Core dumping helper functions.  These are the only things you should
2342  * do on a core-file: use only these functions to write out all the
2343  * necessary info.
2344  */
2345 int dump_write(struct file *file, const void *addr, int nr)
2346 {
2347         return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2348 }
2349 EXPORT_SYMBOL(dump_write);
2350
2351 int dump_seek(struct file *file, loff_t off)
2352 {
2353         int ret = 1;
2354
2355         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2356                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2357                         return 0;
2358         } else {
2359                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2360
2361                 if (!buf)
2362                         return 0;
2363                 while (off > 0) {
2364                         unsigned long n = off;
2365
2366                         if (n > PAGE_SIZE)
2367                                 n = PAGE_SIZE;
2368                         if (!dump_write(file, buf, n)) {
2369                                 ret = 0;
2370                                 break;
2371                         }
2372                         off -= n;
2373                 }
2374                 free_page((unsigned long)buf);
2375         }
2376         return ret;
2377 }
2378 EXPORT_SYMBOL(dump_seek);