b0695a9900ef0d095cb2a3726f2c6526360459dd
[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
66 #include <trace/events/sched.h>
67
68 int core_uses_pid;
69 char core_pattern[CORENAME_MAX_SIZE] = "core";
70 unsigned int core_pipe_limit;
71 int suid_dumpable = 0;
72
73 struct core_name {
74         char *corename;
75         int used, size;
76 };
77 static atomic_t call_count = ATOMIC_INIT(1);
78
79 /* The maximal length of core_pattern is also specified in sysctl.c */
80
81 static LIST_HEAD(formats);
82 static DEFINE_RWLOCK(binfmt_lock);
83
84 int __register_binfmt(struct linux_binfmt * fmt, int insert)
85 {
86         if (!fmt)
87                 return -EINVAL;
88         write_lock(&binfmt_lock);
89         insert ? list_add(&fmt->lh, &formats) :
90                  list_add_tail(&fmt->lh, &formats);
91         write_unlock(&binfmt_lock);
92         return 0;       
93 }
94
95 EXPORT_SYMBOL(__register_binfmt);
96
97 void unregister_binfmt(struct linux_binfmt * fmt)
98 {
99         write_lock(&binfmt_lock);
100         list_del(&fmt->lh);
101         write_unlock(&binfmt_lock);
102 }
103
104 EXPORT_SYMBOL(unregister_binfmt);
105
106 static inline void put_binfmt(struct linux_binfmt * fmt)
107 {
108         module_put(fmt->module);
109 }
110
111 /*
112  * Note that a shared library must be both readable and executable due to
113  * security reasons.
114  *
115  * Also note that we take the address to load from from the file itself.
116  */
117 SYSCALL_DEFINE1(uselib, const char __user *, library)
118 {
119         struct file *file;
120         char *tmp = getname(library);
121         int error = PTR_ERR(tmp);
122         static const struct open_flags uselib_flags = {
123                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
124                 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
125                 .intent = LOOKUP_OPEN
126         };
127
128         if (IS_ERR(tmp))
129                 goto out;
130
131         file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
132         putname(tmp);
133         error = PTR_ERR(file);
134         if (IS_ERR(file))
135                 goto out;
136
137         error = -EINVAL;
138         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
139                 goto exit;
140
141         error = -EACCES;
142         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
143                 goto exit;
144
145         fsnotify_open(file);
146
147         error = -ENOEXEC;
148         if(file->f_op) {
149                 struct linux_binfmt * fmt;
150
151                 read_lock(&binfmt_lock);
152                 list_for_each_entry(fmt, &formats, lh) {
153                         if (!fmt->load_shlib)
154                                 continue;
155                         if (!try_module_get(fmt->module))
156                                 continue;
157                         read_unlock(&binfmt_lock);
158                         error = fmt->load_shlib(file);
159                         read_lock(&binfmt_lock);
160                         put_binfmt(fmt);
161                         if (error != -ENOEXEC)
162                                 break;
163                 }
164                 read_unlock(&binfmt_lock);
165         }
166 exit:
167         fput(file);
168 out:
169         return error;
170 }
171
172 #ifdef CONFIG_MMU
173 /*
174  * The nascent bprm->mm is not visible until exec_mmap() but it can
175  * use a lot of memory, account these pages in current->mm temporary
176  * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
177  * change the counter back via acct_arg_size(0).
178  */
179 static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
180 {
181         struct mm_struct *mm = current->mm;
182         long diff = (long)(pages - bprm->vma_pages);
183
184         if (!mm || !diff)
185                 return;
186
187         bprm->vma_pages = pages;
188         add_mm_counter(mm, MM_ANONPAGES, diff);
189 }
190
191 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
192                 int write)
193 {
194         struct page *page;
195         int ret;
196
197 #ifdef CONFIG_STACK_GROWSUP
198         if (write) {
199                 ret = expand_downwards(bprm->vma, pos);
200                 if (ret < 0)
201                         return NULL;
202         }
203 #endif
204         ret = get_user_pages(current, bprm->mm, pos,
205                         1, write, 1, &page, NULL);
206         if (ret <= 0)
207                 return NULL;
208
209         if (write) {
210                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
211                 struct rlimit *rlim;
212
213                 acct_arg_size(bprm, size / PAGE_SIZE);
214
215                 /*
216                  * We've historically supported up to 32 pages (ARG_MAX)
217                  * of argument strings even with small stacks
218                  */
219                 if (size <= ARG_MAX)
220                         return page;
221
222                 /*
223                  * Limit to 1/4-th the stack size for the argv+env strings.
224                  * This ensures that:
225                  *  - the remaining binfmt code will not run out of stack space,
226                  *  - the program will have a reasonable amount of stack left
227                  *    to work from.
228                  */
229                 rlim = current->signal->rlim;
230                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
231                         put_page(page);
232                         return NULL;
233                 }
234         }
235
236         return page;
237 }
238
239 static void put_arg_page(struct page *page)
240 {
241         put_page(page);
242 }
243
244 static void free_arg_page(struct linux_binprm *bprm, int i)
245 {
246 }
247
248 static void free_arg_pages(struct linux_binprm *bprm)
249 {
250 }
251
252 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
253                 struct page *page)
254 {
255         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
256 }
257
258 static int __bprm_mm_init(struct linux_binprm *bprm)
259 {
260         int err;
261         struct vm_area_struct *vma = NULL;
262         struct mm_struct *mm = bprm->mm;
263
264         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
265         if (!vma)
266                 return -ENOMEM;
267
268         down_write(&mm->mmap_sem);
269         vma->vm_mm = mm;
270
271         /*
272          * Place the stack at the largest stack address the architecture
273          * supports. Later, we'll move this to an appropriate place. We don't
274          * use STACK_TOP because that can depend on attributes which aren't
275          * configured yet.
276          */
277         BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
278         vma->vm_end = STACK_TOP_MAX;
279         vma->vm_start = vma->vm_end - PAGE_SIZE;
280         vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
281         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
282         INIT_LIST_HEAD(&vma->anon_vma_chain);
283
284         err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
285         if (err)
286                 goto err;
287
288         err = insert_vm_struct(mm, vma);
289         if (err)
290                 goto err;
291
292         mm->stack_vm = mm->total_vm = 1;
293         up_write(&mm->mmap_sem);
294         bprm->p = vma->vm_end - sizeof(void *);
295         return 0;
296 err:
297         up_write(&mm->mmap_sem);
298         bprm->vma = NULL;
299         kmem_cache_free(vm_area_cachep, vma);
300         return err;
301 }
302
303 static bool valid_arg_len(struct linux_binprm *bprm, long len)
304 {
305         return len <= MAX_ARG_STRLEN;
306 }
307
308 #else
309
310 static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
311 {
312 }
313
314 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
315                 int write)
316 {
317         struct page *page;
318
319         page = bprm->page[pos / PAGE_SIZE];
320         if (!page && write) {
321                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
322                 if (!page)
323                         return NULL;
324                 bprm->page[pos / PAGE_SIZE] = page;
325         }
326
327         return page;
328 }
329
330 static void put_arg_page(struct page *page)
331 {
332 }
333
334 static void free_arg_page(struct linux_binprm *bprm, int i)
335 {
336         if (bprm->page[i]) {
337                 __free_page(bprm->page[i]);
338                 bprm->page[i] = NULL;
339         }
340 }
341
342 static void free_arg_pages(struct linux_binprm *bprm)
343 {
344         int i;
345
346         for (i = 0; i < MAX_ARG_PAGES; i++)
347                 free_arg_page(bprm, i);
348 }
349
350 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
351                 struct page *page)
352 {
353 }
354
355 static int __bprm_mm_init(struct linux_binprm *bprm)
356 {
357         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
358         return 0;
359 }
360
361 static bool valid_arg_len(struct linux_binprm *bprm, long len)
362 {
363         return len <= bprm->p;
364 }
365
366 #endif /* CONFIG_MMU */
367
368 /*
369  * Create a new mm_struct and populate it with a temporary stack
370  * vm_area_struct.  We don't have enough context at this point to set the stack
371  * flags, permissions, and offset, so we use temporary values.  We'll update
372  * them later in setup_arg_pages().
373  */
374 int bprm_mm_init(struct linux_binprm *bprm)
375 {
376         int err;
377         struct mm_struct *mm = NULL;
378
379         bprm->mm = mm = mm_alloc();
380         err = -ENOMEM;
381         if (!mm)
382                 goto err;
383
384         err = init_new_context(current, mm);
385         if (err)
386                 goto err;
387
388         err = __bprm_mm_init(bprm);
389         if (err)
390                 goto err;
391
392         return 0;
393
394 err:
395         if (mm) {
396                 bprm->mm = NULL;
397                 mmdrop(mm);
398         }
399
400         return err;
401 }
402
403 struct user_arg_ptr {
404 #ifdef CONFIG_COMPAT
405         bool is_compat;
406 #endif
407         union {
408                 const char __user *const __user *native;
409 #ifdef CONFIG_COMPAT
410                 compat_uptr_t __user *compat;
411 #endif
412         } ptr;
413 };
414
415 static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
416 {
417         const char __user *native;
418
419 #ifdef CONFIG_COMPAT
420         if (unlikely(argv.is_compat)) {
421                 compat_uptr_t compat;
422
423                 if (get_user(compat, argv.ptr.compat + nr))
424                         return ERR_PTR(-EFAULT);
425
426                 return compat_ptr(compat);
427         }
428 #endif
429
430         if (get_user(native, argv.ptr.native + nr))
431                 return ERR_PTR(-EFAULT);
432
433         return native;
434 }
435
436 /*
437  * count() counts the number of strings in array ARGV.
438  */
439 static int count(struct user_arg_ptr argv, int max)
440 {
441         int i = 0;
442
443         if (argv.ptr.native != NULL) {
444                 for (;;) {
445                         const char __user *p = get_user_arg_ptr(argv, i);
446
447                         if (!p)
448                                 break;
449
450                         if (IS_ERR(p))
451                                 return -EFAULT;
452
453                         if (i++ >= max)
454                                 return -E2BIG;
455
456                         if (fatal_signal_pending(current))
457                                 return -ERESTARTNOHAND;
458                         cond_resched();
459                 }
460         }
461         return i;
462 }
463
464 /*
465  * 'copy_strings()' copies argument/environment strings from the old
466  * processes's memory to the new process's stack.  The call to get_user_pages()
467  * ensures the destination page is created and not swapped out.
468  */
469 static int copy_strings(int argc, struct user_arg_ptr argv,
470                         struct linux_binprm *bprm)
471 {
472         struct page *kmapped_page = NULL;
473         char *kaddr = NULL;
474         unsigned long kpos = 0;
475         int ret;
476
477         while (argc-- > 0) {
478                 const char __user *str;
479                 int len;
480                 unsigned long pos;
481
482                 ret = -EFAULT;
483                 str = get_user_arg_ptr(argv, argc);
484                 if (IS_ERR(str))
485                         goto out;
486
487                 len = strnlen_user(str, MAX_ARG_STRLEN);
488                 if (!len)
489                         goto out;
490
491                 ret = -E2BIG;
492                 if (!valid_arg_len(bprm, len))
493                         goto out;
494
495                 /* We're going to work our way backwords. */
496                 pos = bprm->p;
497                 str += len;
498                 bprm->p -= len;
499
500                 while (len > 0) {
501                         int offset, bytes_to_copy;
502
503                         if (fatal_signal_pending(current)) {
504                                 ret = -ERESTARTNOHAND;
505                                 goto out;
506                         }
507                         cond_resched();
508
509                         offset = pos % PAGE_SIZE;
510                         if (offset == 0)
511                                 offset = PAGE_SIZE;
512
513                         bytes_to_copy = offset;
514                         if (bytes_to_copy > len)
515                                 bytes_to_copy = len;
516
517                         offset -= bytes_to_copy;
518                         pos -= bytes_to_copy;
519                         str -= bytes_to_copy;
520                         len -= bytes_to_copy;
521
522                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
523                                 struct page *page;
524
525                                 page = get_arg_page(bprm, pos, 1);
526                                 if (!page) {
527                                         ret = -E2BIG;
528                                         goto out;
529                                 }
530
531                                 if (kmapped_page) {
532                                         flush_kernel_dcache_page(kmapped_page);
533                                         kunmap(kmapped_page);
534                                         put_arg_page(kmapped_page);
535                                 }
536                                 kmapped_page = page;
537                                 kaddr = kmap(kmapped_page);
538                                 kpos = pos & PAGE_MASK;
539                                 flush_arg_page(bprm, kpos, kmapped_page);
540                         }
541                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
542                                 ret = -EFAULT;
543                                 goto out;
544                         }
545                 }
546         }
547         ret = 0;
548 out:
549         if (kmapped_page) {
550                 flush_kernel_dcache_page(kmapped_page);
551                 kunmap(kmapped_page);
552                 put_arg_page(kmapped_page);
553         }
554         return ret;
555 }
556
557 /*
558  * Like copy_strings, but get argv and its values from kernel memory.
559  */
560 int copy_strings_kernel(int argc, const char *const *__argv,
561                         struct linux_binprm *bprm)
562 {
563         int r;
564         mm_segment_t oldfs = get_fs();
565         struct user_arg_ptr argv = {
566                 .ptr.native = (const char __user *const  __user *)__argv,
567         };
568
569         set_fs(KERNEL_DS);
570         r = copy_strings(argc, argv, bprm);
571         set_fs(oldfs);
572
573         return r;
574 }
575 EXPORT_SYMBOL(copy_strings_kernel);
576
577 #ifdef CONFIG_MMU
578
579 /*
580  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
581  * the binfmt code determines where the new stack should reside, we shift it to
582  * its final location.  The process proceeds as follows:
583  *
584  * 1) Use shift to calculate the new vma endpoints.
585  * 2) Extend vma to cover both the old and new ranges.  This ensures the
586  *    arguments passed to subsequent functions are consistent.
587  * 3) Move vma's page tables to the new range.
588  * 4) Free up any cleared pgd range.
589  * 5) Shrink the vma to cover only the new range.
590  */
591 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
592 {
593         struct mm_struct *mm = vma->vm_mm;
594         unsigned long old_start = vma->vm_start;
595         unsigned long old_end = vma->vm_end;
596         unsigned long length = old_end - old_start;
597         unsigned long new_start = old_start - shift;
598         unsigned long new_end = old_end - shift;
599         struct mmu_gather tlb;
600
601         BUG_ON(new_start > new_end);
602
603         /*
604          * ensure there are no vmas between where we want to go
605          * and where we are
606          */
607         if (vma != find_vma(mm, new_start))
608                 return -EFAULT;
609
610         /*
611          * cover the whole range: [new_start, old_end)
612          */
613         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
614                 return -ENOMEM;
615
616         /*
617          * move the page tables downwards, on failure we rely on
618          * process cleanup to remove whatever mess we made.
619          */
620         if (length != move_page_tables(vma, old_start,
621                                        vma, new_start, length))
622                 return -ENOMEM;
623
624         lru_add_drain();
625         tlb_gather_mmu(&tlb, mm, 0);
626         if (new_end > old_start) {
627                 /*
628                  * when the old and new regions overlap clear from new_end.
629                  */
630                 free_pgd_range(&tlb, new_end, old_end, new_end,
631                         vma->vm_next ? vma->vm_next->vm_start : 0);
632         } else {
633                 /*
634                  * otherwise, clean from old_start; this is done to not touch
635                  * the address space in [new_end, old_start) some architectures
636                  * have constraints on va-space that make this illegal (IA64) -
637                  * for the others its just a little faster.
638                  */
639                 free_pgd_range(&tlb, old_start, old_end, new_end,
640                         vma->vm_next ? vma->vm_next->vm_start : 0);
641         }
642         tlb_finish_mmu(&tlb, new_end, old_end);
643
644         /*
645          * Shrink the vma to just the new range.  Always succeeds.
646          */
647         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
648
649         return 0;
650 }
651
652 /*
653  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
654  * the stack is optionally relocated, and some extra space is added.
655  */
656 int setup_arg_pages(struct linux_binprm *bprm,
657                     unsigned long stack_top,
658                     int executable_stack)
659 {
660         unsigned long ret;
661         unsigned long stack_shift;
662         struct mm_struct *mm = current->mm;
663         struct vm_area_struct *vma = bprm->vma;
664         struct vm_area_struct *prev = NULL;
665         unsigned long vm_flags;
666         unsigned long stack_base;
667         unsigned long stack_size;
668         unsigned long stack_expand;
669         unsigned long rlim_stack;
670
671 #ifdef CONFIG_STACK_GROWSUP
672         /* Limit stack size to 1GB */
673         stack_base = rlimit_max(RLIMIT_STACK);
674         if (stack_base > (1 << 30))
675                 stack_base = 1 << 30;
676
677         /* Make sure we didn't let the argument array grow too large. */
678         if (vma->vm_end - vma->vm_start > stack_base)
679                 return -ENOMEM;
680
681         stack_base = PAGE_ALIGN(stack_top - stack_base);
682
683         stack_shift = vma->vm_start - stack_base;
684         mm->arg_start = bprm->p - stack_shift;
685         bprm->p = vma->vm_end - stack_shift;
686 #else
687         stack_top = arch_align_stack(stack_top);
688         stack_top = PAGE_ALIGN(stack_top);
689
690         if (unlikely(stack_top < mmap_min_addr) ||
691             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
692                 return -ENOMEM;
693
694         stack_shift = vma->vm_end - stack_top;
695
696         bprm->p -= stack_shift;
697         mm->arg_start = bprm->p;
698 #endif
699
700         if (bprm->loader)
701                 bprm->loader -= stack_shift;
702         bprm->exec -= stack_shift;
703
704         down_write(&mm->mmap_sem);
705         vm_flags = VM_STACK_FLAGS;
706
707         /*
708          * Adjust stack execute permissions; explicitly enable for
709          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
710          * (arch default) otherwise.
711          */
712         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
713                 vm_flags |= VM_EXEC;
714         else if (executable_stack == EXSTACK_DISABLE_X)
715                 vm_flags &= ~VM_EXEC;
716         vm_flags |= mm->def_flags;
717         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
718
719         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
720                         vm_flags);
721         if (ret)
722                 goto out_unlock;
723         BUG_ON(prev != vma);
724
725         /* Move stack pages down in memory. */
726         if (stack_shift) {
727                 ret = shift_arg_pages(vma, stack_shift);
728                 if (ret)
729                         goto out_unlock;
730         }
731
732         /* mprotect_fixup is overkill to remove the temporary stack flags */
733         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
734
735         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
736         stack_size = vma->vm_end - vma->vm_start;
737         /*
738          * Align this down to a page boundary as expand_stack
739          * will align it up.
740          */
741         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
742 #ifdef CONFIG_STACK_GROWSUP
743         if (stack_size + stack_expand > rlim_stack)
744                 stack_base = vma->vm_start + rlim_stack;
745         else
746                 stack_base = vma->vm_end + stack_expand;
747 #else
748         if (stack_size + stack_expand > rlim_stack)
749                 stack_base = vma->vm_end - rlim_stack;
750         else
751                 stack_base = vma->vm_start - stack_expand;
752 #endif
753         current->mm->start_stack = bprm->p;
754         ret = expand_stack(vma, stack_base);
755         if (ret)
756                 ret = -EFAULT;
757
758 out_unlock:
759         up_write(&mm->mmap_sem);
760         return ret;
761 }
762 EXPORT_SYMBOL(setup_arg_pages);
763
764 #endif /* CONFIG_MMU */
765
766 struct file *open_exec(const char *name)
767 {
768         struct file *file;
769         int err;
770         static const struct open_flags open_exec_flags = {
771                 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
772                 .acc_mode = MAY_EXEC | MAY_OPEN,
773                 .intent = LOOKUP_OPEN
774         };
775
776         file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
777         if (IS_ERR(file))
778                 goto out;
779
780         err = -EACCES;
781         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
782                 goto exit;
783
784         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
785                 goto exit;
786
787         fsnotify_open(file);
788
789         err = deny_write_access(file);
790         if (err)
791                 goto exit;
792
793 out:
794         return file;
795
796 exit:
797         fput(file);
798         return ERR_PTR(err);
799 }
800 EXPORT_SYMBOL(open_exec);
801
802 int kernel_read(struct file *file, loff_t offset,
803                 char *addr, unsigned long count)
804 {
805         mm_segment_t old_fs;
806         loff_t pos = offset;
807         int result;
808
809         old_fs = get_fs();
810         set_fs(get_ds());
811         /* The cast to a user pointer is valid due to the set_fs() */
812         result = vfs_read(file, (void __user *)addr, count, &pos);
813         set_fs(old_fs);
814         return result;
815 }
816
817 EXPORT_SYMBOL(kernel_read);
818
819 static int exec_mmap(struct mm_struct *mm)
820 {
821         struct task_struct *tsk;
822         struct mm_struct * old_mm, *active_mm;
823
824         /* Notify parent that we're no longer interested in the old VM */
825         tsk = current;
826         old_mm = current->mm;
827         sync_mm_rss(tsk, old_mm);
828         mm_release(tsk, old_mm);
829
830         if (old_mm) {
831                 /*
832                  * Make sure that if there is a core dump in progress
833                  * for the old mm, we get out and die instead of going
834                  * through with the exec.  We must hold mmap_sem around
835                  * checking core_state and changing tsk->mm.
836                  */
837                 down_read(&old_mm->mmap_sem);
838                 if (unlikely(old_mm->core_state)) {
839                         up_read(&old_mm->mmap_sem);
840                         return -EINTR;
841                 }
842         }
843         task_lock(tsk);
844         active_mm = tsk->active_mm;
845         tsk->mm = mm;
846         tsk->active_mm = mm;
847         activate_mm(active_mm, mm);
848         task_unlock(tsk);
849         arch_pick_mmap_layout(mm);
850         if (old_mm) {
851                 up_read(&old_mm->mmap_sem);
852                 BUG_ON(active_mm != old_mm);
853                 mm_update_next_owner(old_mm);
854                 mmput(old_mm);
855                 return 0;
856         }
857         mmdrop(active_mm);
858         return 0;
859 }
860
861 /*
862  * This function makes sure the current process has its own signal table,
863  * so that flush_signal_handlers can later reset the handlers without
864  * disturbing other processes.  (Other processes might share the signal
865  * table via the CLONE_SIGHAND option to clone().)
866  */
867 static int de_thread(struct task_struct *tsk)
868 {
869         struct signal_struct *sig = tsk->signal;
870         struct sighand_struct *oldsighand = tsk->sighand;
871         spinlock_t *lock = &oldsighand->siglock;
872
873         if (thread_group_empty(tsk))
874                 goto no_thread_group;
875
876         /*
877          * Kill all other threads in the thread group.
878          */
879         spin_lock_irq(lock);
880         if (signal_group_exit(sig)) {
881                 /*
882                  * Another group action in progress, just
883                  * return so that the signal is processed.
884                  */
885                 spin_unlock_irq(lock);
886                 return -EAGAIN;
887         }
888
889         sig->group_exit_task = tsk;
890         sig->notify_count = zap_other_threads(tsk);
891         if (!thread_group_leader(tsk))
892                 sig->notify_count--;
893
894         while (sig->notify_count) {
895                 __set_current_state(TASK_UNINTERRUPTIBLE);
896                 spin_unlock_irq(lock);
897                 schedule();
898                 spin_lock_irq(lock);
899         }
900         spin_unlock_irq(lock);
901
902         /*
903          * At this point all other threads have exited, all we have to
904          * do is to wait for the thread group leader to become inactive,
905          * and to assume its PID:
906          */
907         if (!thread_group_leader(tsk)) {
908                 struct task_struct *leader = tsk->group_leader;
909
910                 sig->notify_count = -1; /* for exit_notify() */
911                 for (;;) {
912                         write_lock_irq(&tasklist_lock);
913                         if (likely(leader->exit_state))
914                                 break;
915                         __set_current_state(TASK_UNINTERRUPTIBLE);
916                         write_unlock_irq(&tasklist_lock);
917                         schedule();
918                 }
919
920                 /*
921                  * The only record we have of the real-time age of a
922                  * process, regardless of execs it's done, is start_time.
923                  * All the past CPU time is accumulated in signal_struct
924                  * from sister threads now dead.  But in this non-leader
925                  * exec, nothing survives from the original leader thread,
926                  * whose birth marks the true age of this process now.
927                  * When we take on its identity by switching to its PID, we
928                  * also take its birthdate (always earlier than our own).
929                  */
930                 tsk->start_time = leader->start_time;
931
932                 BUG_ON(!same_thread_group(leader, tsk));
933                 BUG_ON(has_group_leader_pid(tsk));
934                 /*
935                  * An exec() starts a new thread group with the
936                  * TGID of the previous thread group. Rehash the
937                  * two threads with a switched PID, and release
938                  * the former thread group leader:
939                  */
940
941                 /* Become a process group leader with the old leader's pid.
942                  * The old leader becomes a thread of the this thread group.
943                  * Note: The old leader also uses this pid until release_task
944                  *       is called.  Odd but simple and correct.
945                  */
946                 detach_pid(tsk, PIDTYPE_PID);
947                 tsk->pid = leader->pid;
948                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
949                 transfer_pid(leader, tsk, PIDTYPE_PGID);
950                 transfer_pid(leader, tsk, PIDTYPE_SID);
951
952                 list_replace_rcu(&leader->tasks, &tsk->tasks);
953                 list_replace_init(&leader->sibling, &tsk->sibling);
954
955                 tsk->group_leader = tsk;
956                 leader->group_leader = tsk;
957
958                 tsk->exit_signal = SIGCHLD;
959                 leader->exit_signal = -1;
960
961                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
962                 leader->exit_state = EXIT_DEAD;
963
964                 /*
965                  * We are going to release_task()->ptrace_unlink() silently,
966                  * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
967                  * the tracer wont't block again waiting for this thread.
968                  */
969                 if (unlikely(leader->ptrace))
970                         __wake_up_parent(leader, leader->parent);
971                 write_unlock_irq(&tasklist_lock);
972
973                 release_task(leader);
974         }
975
976         sig->group_exit_task = NULL;
977         sig->notify_count = 0;
978
979 no_thread_group:
980         if (current->mm)
981                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
982
983         exit_itimers(sig);
984         flush_itimer_signals();
985
986         if (atomic_read(&oldsighand->count) != 1) {
987                 struct sighand_struct *newsighand;
988                 /*
989                  * This ->sighand is shared with the CLONE_SIGHAND
990                  * but not CLONE_THREAD task, switch to the new one.
991                  */
992                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
993                 if (!newsighand)
994                         return -ENOMEM;
995
996                 atomic_set(&newsighand->count, 1);
997                 memcpy(newsighand->action, oldsighand->action,
998                        sizeof(newsighand->action));
999
1000                 write_lock_irq(&tasklist_lock);
1001                 spin_lock(&oldsighand->siglock);
1002                 rcu_assign_pointer(tsk->sighand, newsighand);
1003                 spin_unlock(&oldsighand->siglock);
1004                 write_unlock_irq(&tasklist_lock);
1005
1006                 __cleanup_sighand(oldsighand);
1007         }
1008
1009         BUG_ON(!thread_group_leader(tsk));
1010         return 0;
1011 }
1012
1013 /*
1014  * These functions flushes out all traces of the currently running executable
1015  * so that a new one can be started
1016  */
1017 static void flush_old_files(struct files_struct * files)
1018 {
1019         long j = -1;
1020         struct fdtable *fdt;
1021
1022         spin_lock(&files->file_lock);
1023         for (;;) {
1024                 unsigned long set, i;
1025
1026                 j++;
1027                 i = j * __NFDBITS;
1028                 fdt = files_fdtable(files);
1029                 if (i >= fdt->max_fds)
1030                         break;
1031                 set = fdt->close_on_exec->fds_bits[j];
1032                 if (!set)
1033                         continue;
1034                 fdt->close_on_exec->fds_bits[j] = 0;
1035                 spin_unlock(&files->file_lock);
1036                 for ( ; set ; i++,set >>= 1) {
1037                         if (set & 1) {
1038                                 sys_close(i);
1039                         }
1040                 }
1041                 spin_lock(&files->file_lock);
1042
1043         }
1044         spin_unlock(&files->file_lock);
1045 }
1046
1047 char *get_task_comm(char *buf, struct task_struct *tsk)
1048 {
1049         /* buf must be at least sizeof(tsk->comm) in size */
1050         task_lock(tsk);
1051         strncpy(buf, tsk->comm, sizeof(tsk->comm));
1052         task_unlock(tsk);
1053         return buf;
1054 }
1055 EXPORT_SYMBOL_GPL(get_task_comm);
1056
1057 void set_task_comm(struct task_struct *tsk, char *buf)
1058 {
1059         task_lock(tsk);
1060
1061         trace_task_rename(tsk, buf);
1062
1063         /*
1064          * Threads may access current->comm without holding
1065          * the task lock, so write the string carefully.
1066          * Readers without a lock may see incomplete new
1067          * names but are safe from non-terminating string reads.
1068          */
1069         memset(tsk->comm, 0, TASK_COMM_LEN);
1070         wmb();
1071         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1072         task_unlock(tsk);
1073         perf_event_comm(tsk);
1074 }
1075
1076 static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)
1077 {
1078         int i, ch;
1079
1080         /* Copies the binary name from after last slash */
1081         for (i = 0; (ch = *(fn++)) != '\0';) {
1082                 if (ch == '/')
1083                         i = 0; /* overwrite what we wrote */
1084                 else
1085                         if (i < len - 1)
1086                                 tcomm[i++] = ch;
1087         }
1088         tcomm[i] = '\0';
1089 }
1090
1091 int flush_old_exec(struct linux_binprm * bprm)
1092 {
1093         int retval;
1094
1095         /*
1096          * Make sure we have a private signal table and that
1097          * we are unassociated from the previous thread group.
1098          */
1099         retval = de_thread(current);
1100         if (retval)
1101                 goto out;
1102
1103         set_mm_exe_file(bprm->mm, bprm->file);
1104
1105         filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));
1106         /*
1107          * Release all of the old mmap stuff
1108          */
1109         acct_arg_size(bprm, 0);
1110         retval = exec_mmap(bprm->mm);
1111         if (retval)
1112                 goto out;
1113
1114         bprm->mm = NULL;                /* We're using it now */
1115
1116         set_fs(USER_DS);
1117         current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1118         flush_thread();
1119         current->personality &= ~bprm->per_clear;
1120
1121         return 0;
1122
1123 out:
1124         return retval;
1125 }
1126 EXPORT_SYMBOL(flush_old_exec);
1127
1128 void would_dump(struct linux_binprm *bprm, struct file *file)
1129 {
1130         if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
1131                 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1132 }
1133 EXPORT_SYMBOL(would_dump);
1134
1135 void setup_new_exec(struct linux_binprm * bprm)
1136 {
1137         arch_pick_mmap_layout(current->mm);
1138
1139         /* This is the point of no return */
1140         current->sas_ss_sp = current->sas_ss_size = 0;
1141
1142         if (current_euid() == current_uid() && current_egid() == current_gid())
1143                 set_dumpable(current->mm, 1);
1144         else
1145                 set_dumpable(current->mm, suid_dumpable);
1146
1147         set_task_comm(current, bprm->tcomm);
1148
1149         /* Set the new mm task size. We have to do that late because it may
1150          * depend on TIF_32BIT which is only updated in flush_thread() on
1151          * some architectures like powerpc
1152          */
1153         current->mm->task_size = TASK_SIZE;
1154
1155         /* install the new credentials */
1156         if (bprm->cred->uid != current_euid() ||
1157             bprm->cred->gid != current_egid()) {
1158                 current->pdeath_signal = 0;
1159         } else {
1160                 would_dump(bprm, bprm->file);
1161                 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1162                         set_dumpable(current->mm, suid_dumpable);
1163         }
1164
1165         /*
1166          * Flush performance counters when crossing a
1167          * security domain:
1168          */
1169         if (!get_dumpable(current->mm))
1170                 perf_event_exit_task(current);
1171
1172         /* An exec changes our domain. We are no longer part of the thread
1173            group */
1174
1175         current->self_exec_id++;
1176                         
1177         flush_signal_handlers(current, 0);
1178         flush_old_files(current->files);
1179 }
1180 EXPORT_SYMBOL(setup_new_exec);
1181
1182 /*
1183  * Prepare credentials and lock ->cred_guard_mutex.
1184  * install_exec_creds() commits the new creds and drops the lock.
1185  * Or, if exec fails before, free_bprm() should release ->cred and
1186  * and unlock.
1187  */
1188 int prepare_bprm_creds(struct linux_binprm *bprm)
1189 {
1190         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1191                 return -ERESTARTNOINTR;
1192
1193         bprm->cred = prepare_exec_creds();
1194         if (likely(bprm->cred))
1195                 return 0;
1196
1197         mutex_unlock(&current->signal->cred_guard_mutex);
1198         return -ENOMEM;
1199 }
1200
1201 void free_bprm(struct linux_binprm *bprm)
1202 {
1203         free_arg_pages(bprm);
1204         if (bprm->cred) {
1205                 mutex_unlock(&current->signal->cred_guard_mutex);
1206                 abort_creds(bprm->cred);
1207         }
1208         kfree(bprm);
1209 }
1210
1211 /*
1212  * install the new credentials for this executable
1213  */
1214 void install_exec_creds(struct linux_binprm *bprm)
1215 {
1216         security_bprm_committing_creds(bprm);
1217
1218         commit_creds(bprm->cred);
1219         bprm->cred = NULL;
1220         /*
1221          * cred_guard_mutex must be held at least to this point to prevent
1222          * ptrace_attach() from altering our determination of the task's
1223          * credentials; any time after this it may be unlocked.
1224          */
1225         security_bprm_committed_creds(bprm);
1226         mutex_unlock(&current->signal->cred_guard_mutex);
1227 }
1228 EXPORT_SYMBOL(install_exec_creds);
1229
1230 /*
1231  * determine how safe it is to execute the proposed program
1232  * - the caller must hold ->cred_guard_mutex to protect against
1233  *   PTRACE_ATTACH
1234  */
1235 static int check_unsafe_exec(struct linux_binprm *bprm)
1236 {
1237         struct task_struct *p = current, *t;
1238         unsigned n_fs;
1239         int res = 0;
1240
1241         if (p->ptrace) {
1242                 if (p->ptrace & PT_PTRACE_CAP)
1243                         bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1244                 else
1245                         bprm->unsafe |= LSM_UNSAFE_PTRACE;
1246         }
1247
1248         n_fs = 1;
1249         spin_lock(&p->fs->lock);
1250         rcu_read_lock();
1251         for (t = next_thread(p); t != p; t = next_thread(t)) {
1252                 if (t->fs == p->fs)
1253                         n_fs++;
1254         }
1255         rcu_read_unlock();
1256
1257         if (p->fs->users > n_fs) {
1258                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1259         } else {
1260                 res = -EAGAIN;
1261                 if (!p->fs->in_exec) {
1262                         p->fs->in_exec = 1;
1263                         res = 1;
1264                 }
1265         }
1266         spin_unlock(&p->fs->lock);
1267
1268         return res;
1269 }
1270
1271 /* 
1272  * Fill the binprm structure from the inode. 
1273  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1274  *
1275  * This may be called multiple times for binary chains (scripts for example).
1276  */
1277 int prepare_binprm(struct linux_binprm *bprm)
1278 {
1279         umode_t mode;
1280         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1281         int retval;
1282
1283         mode = inode->i_mode;
1284         if (bprm->file->f_op == NULL)
1285                 return -EACCES;
1286
1287         /* clear any previous set[ug]id data from a previous binary */
1288         bprm->cred->euid = current_euid();
1289         bprm->cred->egid = current_egid();
1290
1291         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
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, KM_USER0);
1345
1346                 for (; offset < PAGE_SIZE && kaddr[offset];
1347                                 offset++, bprm->p++)
1348                         ;
1349
1350                 kunmap_atomic(kaddr, KM_USER0);
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,struct pt_regs *regs)
1370 {
1371         unsigned int depth = bprm->recursion_depth;
1372         int try,retval;
1373         struct linux_binfmt *fmt;
1374         pid_t old_pid;
1375
1376         retval = security_bprm_check(bprm);
1377         if (retval)
1378                 return retval;
1379
1380         retval = audit_bprm(bprm);
1381         if (retval)
1382                 return retval;
1383
1384         /* Need to fetch pid before load_binary changes it */
1385         rcu_read_lock();
1386         old_pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1387         rcu_read_unlock();
1388
1389         retval = -ENOENT;
1390         for (try=0; try<2; try++) {
1391                 read_lock(&binfmt_lock);
1392                 list_for_each_entry(fmt, &formats, lh) {
1393                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1394                         if (!fn)
1395                                 continue;
1396                         if (!try_module_get(fmt->module))
1397                                 continue;
1398                         read_unlock(&binfmt_lock);
1399                         retval = fn(bprm, regs);
1400                         /*
1401                          * Restore the depth counter to its starting value
1402                          * in this call, so we don't have to rely on every
1403                          * load_binary function to restore it on return.
1404                          */
1405                         bprm->recursion_depth = depth;
1406                         if (retval >= 0) {
1407                                 if (depth == 0) {
1408                                         trace_sched_process_exec(current, old_pid, bprm);
1409                                         ptrace_event(PTRACE_EVENT_EXEC, old_pid);
1410                                 }
1411                                 put_binfmt(fmt);
1412                                 allow_write_access(bprm->file);
1413                                 if (bprm->file)
1414                                         fput(bprm->file);
1415                                 bprm->file = NULL;
1416                                 current->did_exec = 1;
1417                                 proc_exec_connector(current);
1418                                 return retval;
1419                         }
1420                         read_lock(&binfmt_lock);
1421                         put_binfmt(fmt);
1422                         if (retval != -ENOEXEC || bprm->mm == NULL)
1423                                 break;
1424                         if (!bprm->file) {
1425                                 read_unlock(&binfmt_lock);
1426                                 return retval;
1427                         }
1428                 }
1429                 read_unlock(&binfmt_lock);
1430 #ifdef CONFIG_MODULES
1431                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1432                         break;
1433                 } else {
1434 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1435                         if (printable(bprm->buf[0]) &&
1436                             printable(bprm->buf[1]) &&
1437                             printable(bprm->buf[2]) &&
1438                             printable(bprm->buf[3]))
1439                                 break; /* -ENOEXEC */
1440                         if (try)
1441                                 break; /* -ENOEXEC */
1442                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1443                 }
1444 #else
1445                 break;
1446 #endif
1447         }
1448         return retval;
1449 }
1450
1451 EXPORT_SYMBOL(search_binary_handler);
1452
1453 /*
1454  * sys_execve() executes a new program.
1455  */
1456 static int do_execve_common(const char *filename,
1457                                 struct user_arg_ptr argv,
1458                                 struct user_arg_ptr envp,
1459                                 struct pt_regs *regs)
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,regs);
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         struct pt_regs *regs)
1587 {
1588         struct user_arg_ptr argv = { .ptr.native = __argv };
1589         struct user_arg_ptr envp = { .ptr.native = __envp };
1590         return do_execve_common(filename, argv, envp, regs);
1591 }
1592
1593 #ifdef CONFIG_COMPAT
1594 int compat_do_execve(char *filename,
1595         compat_uptr_t __user *__argv,
1596         compat_uptr_t __user *__envp,
1597         struct pt_regs *regs)
1598 {
1599         struct user_arg_ptr argv = {
1600                 .is_compat = true,
1601                 .ptr.compat = __argv,
1602         };
1603         struct user_arg_ptr envp = {
1604                 .is_compat = true,
1605                 .ptr.compat = __envp,
1606         };
1607         return do_execve_common(filename, argv, envp, regs);
1608 }
1609 #endif
1610
1611 void set_binfmt(struct linux_binfmt *new)
1612 {
1613         struct mm_struct *mm = current->mm;
1614
1615         if (mm->binfmt)
1616                 module_put(mm->binfmt->module);
1617
1618         mm->binfmt = new;
1619         if (new)
1620                 __module_get(new->module);
1621 }
1622
1623 EXPORT_SYMBOL(set_binfmt);
1624
1625 static int expand_corename(struct core_name *cn)
1626 {
1627         char *old_corename = cn->corename;
1628
1629         cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1630         cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1631
1632         if (!cn->corename) {
1633                 kfree(old_corename);
1634                 return -ENOMEM;
1635         }
1636
1637         return 0;
1638 }
1639
1640 static int cn_printf(struct core_name *cn, const char *fmt, ...)
1641 {
1642         char *cur;
1643         int need;
1644         int ret;
1645         va_list arg;
1646
1647         va_start(arg, fmt);
1648         need = vsnprintf(NULL, 0, fmt, arg);
1649         va_end(arg);
1650
1651         if (likely(need < cn->size - cn->used - 1))
1652                 goto out_printf;
1653
1654         ret = expand_corename(cn);
1655         if (ret)
1656                 goto expand_fail;
1657
1658 out_printf:
1659         cur = cn->corename + cn->used;
1660         va_start(arg, fmt);
1661         vsnprintf(cur, need + 1, fmt, arg);
1662         va_end(arg);
1663         cn->used += need;
1664         return 0;
1665
1666 expand_fail:
1667         return ret;
1668 }
1669
1670 static void cn_escape(char *str)
1671 {
1672         for (; *str; str++)
1673                 if (*str == '/')
1674                         *str = '!';
1675 }
1676
1677 static int cn_print_exe_file(struct core_name *cn)
1678 {
1679         struct file *exe_file;
1680         char *pathbuf, *path;
1681         int ret;
1682
1683         exe_file = get_mm_exe_file(current->mm);
1684         if (!exe_file) {
1685                 char *commstart = cn->corename + cn->used;
1686                 ret = cn_printf(cn, "%s (path unknown)", current->comm);
1687                 cn_escape(commstart);
1688                 return ret;
1689         }
1690
1691         pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1692         if (!pathbuf) {
1693                 ret = -ENOMEM;
1694                 goto put_exe_file;
1695         }
1696
1697         path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1698         if (IS_ERR(path)) {
1699                 ret = PTR_ERR(path);
1700                 goto free_buf;
1701         }
1702
1703         cn_escape(path);
1704
1705         ret = cn_printf(cn, "%s", path);
1706
1707 free_buf:
1708         kfree(pathbuf);
1709 put_exe_file:
1710         fput(exe_file);
1711         return ret;
1712 }
1713
1714 /* format_corename will inspect the pattern parameter, and output a
1715  * name into corename, which must have space for at least
1716  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1717  */
1718 static int format_corename(struct core_name *cn, long signr)
1719 {
1720         const struct cred *cred = current_cred();
1721         const char *pat_ptr = core_pattern;
1722         int ispipe = (*pat_ptr == '|');
1723         int pid_in_pattern = 0;
1724         int err = 0;
1725
1726         cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1727         cn->corename = kmalloc(cn->size, GFP_KERNEL);
1728         cn->used = 0;
1729
1730         if (!cn->corename)
1731                 return -ENOMEM;
1732
1733         /* Repeat as long as we have more pattern to process and more output
1734            space */
1735         while (*pat_ptr) {
1736                 if (*pat_ptr != '%') {
1737                         if (*pat_ptr == 0)
1738                                 goto out;
1739                         err = cn_printf(cn, "%c", *pat_ptr++);
1740                 } else {
1741                         switch (*++pat_ptr) {
1742                         /* single % at the end, drop that */
1743                         case 0:
1744                                 goto out;
1745                         /* Double percent, output one percent */
1746                         case '%':
1747                                 err = cn_printf(cn, "%c", '%');
1748                                 break;
1749                         /* pid */
1750                         case 'p':
1751                                 pid_in_pattern = 1;
1752                                 err = cn_printf(cn, "%d",
1753                                               task_tgid_vnr(current));
1754                                 break;
1755                         /* uid */
1756                         case 'u':
1757                                 err = cn_printf(cn, "%d", cred->uid);
1758                                 break;
1759                         /* gid */
1760                         case 'g':
1761                                 err = cn_printf(cn, "%d", cred->gid);
1762                                 break;
1763                         /* signal that caused the coredump */
1764                         case 's':
1765                                 err = cn_printf(cn, "%ld", signr);
1766                                 break;
1767                         /* UNIX time of coredump */
1768                         case 't': {
1769                                 struct timeval tv;
1770                                 do_gettimeofday(&tv);
1771                                 err = cn_printf(cn, "%lu", tv.tv_sec);
1772                                 break;
1773                         }
1774                         /* hostname */
1775                         case 'h': {
1776                                 char *namestart = cn->corename + cn->used;
1777                                 down_read(&uts_sem);
1778                                 err = cn_printf(cn, "%s",
1779                                               utsname()->nodename);
1780                                 up_read(&uts_sem);
1781                                 cn_escape(namestart);
1782                                 break;
1783                         }
1784                         /* executable */
1785                         case 'e': {
1786                                 char *commstart = cn->corename + cn->used;
1787                                 err = cn_printf(cn, "%s", current->comm);
1788                                 cn_escape(commstart);
1789                                 break;
1790                         }
1791                         case 'E':
1792                                 err = cn_print_exe_file(cn);
1793                                 break;
1794                         /* core limit size */
1795                         case 'c':
1796                                 err = cn_printf(cn, "%lu",
1797                                               rlimit(RLIMIT_CORE));
1798                                 break;
1799                         default:
1800                                 break;
1801                         }
1802                         ++pat_ptr;
1803                 }
1804
1805                 if (err)
1806                         return err;
1807         }
1808
1809         /* Backward compatibility with core_uses_pid:
1810          *
1811          * If core_pattern does not include a %p (as is the default)
1812          * and core_uses_pid is set, then .%pid will be appended to
1813          * the filename. Do not do this for piped commands. */
1814         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1815                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1816                 if (err)
1817                         return err;
1818         }
1819 out:
1820         return ispipe;
1821 }
1822
1823 static int zap_process(struct task_struct *start, int exit_code)
1824 {
1825         struct task_struct *t;
1826         int nr = 0;
1827
1828         start->signal->flags = SIGNAL_GROUP_EXIT;
1829         start->signal->group_exit_code = exit_code;
1830         start->signal->group_stop_count = 0;
1831
1832         t = start;
1833         do {
1834                 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1835                 if (t != current && t->mm) {
1836                         sigaddset(&t->pending.signal, SIGKILL);
1837                         signal_wake_up(t, 1);
1838                         nr++;
1839                 }
1840         } while_each_thread(start, t);
1841
1842         return nr;
1843 }
1844
1845 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1846                                 struct core_state *core_state, int exit_code)
1847 {
1848         struct task_struct *g, *p;
1849         unsigned long flags;
1850         int nr = -EAGAIN;
1851
1852         spin_lock_irq(&tsk->sighand->siglock);
1853         if (!signal_group_exit(tsk->signal)) {
1854                 mm->core_state = core_state;
1855                 nr = zap_process(tsk, exit_code);
1856         }
1857         spin_unlock_irq(&tsk->sighand->siglock);
1858         if (unlikely(nr < 0))
1859                 return nr;
1860
1861         if (atomic_read(&mm->mm_users) == nr + 1)
1862                 goto done;
1863         /*
1864          * We should find and kill all tasks which use this mm, and we should
1865          * count them correctly into ->nr_threads. We don't take tasklist
1866          * lock, but this is safe wrt:
1867          *
1868          * fork:
1869          *      None of sub-threads can fork after zap_process(leader). All
1870          *      processes which were created before this point should be
1871          *      visible to zap_threads() because copy_process() adds the new
1872          *      process to the tail of init_task.tasks list, and lock/unlock
1873          *      of ->siglock provides a memory barrier.
1874          *
1875          * do_exit:
1876          *      The caller holds mm->mmap_sem. This means that the task which
1877          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1878          *      its ->mm.
1879          *
1880          * de_thread:
1881          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1882          *      we must see either old or new leader, this does not matter.
1883          *      However, it can change p->sighand, so lock_task_sighand(p)
1884          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1885          *      it can't fail.
1886          *
1887          *      Note also that "g" can be the old leader with ->mm == NULL
1888          *      and already unhashed and thus removed from ->thread_group.
1889          *      This is OK, __unhash_process()->list_del_rcu() does not
1890          *      clear the ->next pointer, we will find the new leader via
1891          *      next_thread().
1892          */
1893         rcu_read_lock();
1894         for_each_process(g) {
1895                 if (g == tsk->group_leader)
1896                         continue;
1897                 if (g->flags & PF_KTHREAD)
1898                         continue;
1899                 p = g;
1900                 do {
1901                         if (p->mm) {
1902                                 if (unlikely(p->mm == mm)) {
1903                                         lock_task_sighand(p, &flags);
1904                                         nr += zap_process(p, exit_code);
1905                                         unlock_task_sighand(p, &flags);
1906                                 }
1907                                 break;
1908                         }
1909                 } while_each_thread(g, p);
1910         }
1911         rcu_read_unlock();
1912 done:
1913         atomic_set(&core_state->nr_threads, nr);
1914         return nr;
1915 }
1916
1917 static int coredump_wait(int exit_code, struct core_state *core_state)
1918 {
1919         struct task_struct *tsk = current;
1920         struct mm_struct *mm = tsk->mm;
1921         int core_waiters = -EBUSY;
1922
1923         init_completion(&core_state->startup);
1924         core_state->dumper.task = tsk;
1925         core_state->dumper.next = NULL;
1926
1927         down_write(&mm->mmap_sem);
1928         if (!mm->core_state)
1929                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1930         up_write(&mm->mmap_sem);
1931
1932         if (core_waiters > 0)
1933                 wait_for_completion(&core_state->startup);
1934
1935         return core_waiters;
1936 }
1937
1938 static void coredump_finish(struct mm_struct *mm)
1939 {
1940         struct core_thread *curr, *next;
1941         struct task_struct *task;
1942
1943         next = mm->core_state->dumper.next;
1944         while ((curr = next) != NULL) {
1945                 next = curr->next;
1946                 task = curr->task;
1947                 /*
1948                  * see exit_mm(), curr->task must not see
1949                  * ->task == NULL before we read ->next.
1950                  */
1951                 smp_mb();
1952                 curr->task = NULL;
1953                 wake_up_process(task);
1954         }
1955
1956         mm->core_state = NULL;
1957 }
1958
1959 /*
1960  * set_dumpable converts traditional three-value dumpable to two flags and
1961  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1962  * these bits are not changed atomically.  So get_dumpable can observe the
1963  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1964  * return either old dumpable or new one by paying attention to the order of
1965  * modifying the bits.
1966  *
1967  * dumpable |   mm->flags (binary)
1968  * old  new | initial interim  final
1969  * ---------+-----------------------
1970  *  0    1  |   00      01      01
1971  *  0    2  |   00      10(*)   11
1972  *  1    0  |   01      00      00
1973  *  1    2  |   01      11      11
1974  *  2    0  |   11      10(*)   00
1975  *  2    1  |   11      11      01
1976  *
1977  * (*) get_dumpable regards interim value of 10 as 11.
1978  */
1979 void set_dumpable(struct mm_struct *mm, int value)
1980 {
1981         switch (value) {
1982         case 0:
1983                 clear_bit(MMF_DUMPABLE, &mm->flags);
1984                 smp_wmb();
1985                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1986                 break;
1987         case 1:
1988                 set_bit(MMF_DUMPABLE, &mm->flags);
1989                 smp_wmb();
1990                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1991                 break;
1992         case 2:
1993                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1994                 smp_wmb();
1995                 set_bit(MMF_DUMPABLE, &mm->flags);
1996                 break;
1997         }
1998 }
1999
2000 static int __get_dumpable(unsigned long mm_flags)
2001 {
2002         int ret;
2003
2004         ret = mm_flags & MMF_DUMPABLE_MASK;
2005         return (ret >= 2) ? 2 : ret;
2006 }
2007
2008 int get_dumpable(struct mm_struct *mm)
2009 {
2010         return __get_dumpable(mm->flags);
2011 }
2012
2013 static void wait_for_dump_helpers(struct file *file)
2014 {
2015         struct pipe_inode_info *pipe;
2016
2017         pipe = file->f_path.dentry->d_inode->i_pipe;
2018
2019         pipe_lock(pipe);
2020         pipe->readers++;
2021         pipe->writers--;
2022
2023         while ((pipe->readers > 1) && (!signal_pending(current))) {
2024                 wake_up_interruptible_sync(&pipe->wait);
2025                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2026                 pipe_wait(pipe);
2027         }
2028
2029         pipe->readers--;
2030         pipe->writers++;
2031         pipe_unlock(pipe);
2032
2033 }
2034
2035
2036 /*
2037  * umh_pipe_setup
2038  * helper function to customize the process used
2039  * to collect the core in userspace.  Specifically
2040  * it sets up a pipe and installs it as fd 0 (stdin)
2041  * for the process.  Returns 0 on success, or
2042  * PTR_ERR on failure.
2043  * Note that it also sets the core limit to 1.  This
2044  * is a special value that we use to trap recursive
2045  * core dumps
2046  */
2047 static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2048 {
2049         struct file *rp, *wp;
2050         struct fdtable *fdt;
2051         struct coredump_params *cp = (struct coredump_params *)info->data;
2052         struct files_struct *cf = current->files;
2053
2054         wp = create_write_pipe(0);
2055         if (IS_ERR(wp))
2056                 return PTR_ERR(wp);
2057
2058         rp = create_read_pipe(wp, 0);
2059         if (IS_ERR(rp)) {
2060                 free_write_pipe(wp);
2061                 return PTR_ERR(rp);
2062         }
2063
2064         cp->file = wp;
2065
2066         sys_close(0);
2067         fd_install(0, rp);
2068         spin_lock(&cf->file_lock);
2069         fdt = files_fdtable(cf);
2070         FD_SET(0, fdt->open_fds);
2071         FD_CLR(0, fdt->close_on_exec);
2072         spin_unlock(&cf->file_lock);
2073
2074         /* and disallow core files too */
2075         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2076
2077         return 0;
2078 }
2079
2080 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2081 {
2082         struct core_state core_state;
2083         struct core_name cn;
2084         struct mm_struct *mm = current->mm;
2085         struct linux_binfmt * binfmt;
2086         const struct cred *old_cred;
2087         struct cred *cred;
2088         int retval = 0;
2089         int flag = 0;
2090         int ispipe;
2091         static atomic_t core_dump_count = ATOMIC_INIT(0);
2092         struct coredump_params cprm = {
2093                 .signr = signr,
2094                 .regs = regs,
2095                 .limit = rlimit(RLIMIT_CORE),
2096                 /*
2097                  * We must use the same mm->flags while dumping core to avoid
2098                  * inconsistency of bit flags, since this flag is not protected
2099                  * by any locks.
2100                  */
2101                 .mm_flags = mm->flags,
2102         };
2103
2104         audit_core_dumps(signr);
2105
2106         binfmt = mm->binfmt;
2107         if (!binfmt || !binfmt->core_dump)
2108                 goto fail;
2109         if (!__get_dumpable(cprm.mm_flags))
2110                 goto fail;
2111
2112         cred = prepare_creds();
2113         if (!cred)
2114                 goto fail;
2115         /*
2116          *      We cannot trust fsuid as being the "true" uid of the
2117          *      process nor do we know its entire history. We only know it
2118          *      was tainted so we dump it as root in mode 2.
2119          */
2120         if (__get_dumpable(cprm.mm_flags) == 2) {
2121                 /* Setuid core dump mode */
2122                 flag = O_EXCL;          /* Stop rewrite attacks */
2123                 cred->fsuid = 0;        /* Dump root private */
2124         }
2125
2126         retval = coredump_wait(exit_code, &core_state);
2127         if (retval < 0)
2128                 goto fail_creds;
2129
2130         old_cred = override_creds(cred);
2131
2132         /*
2133          * Clear any false indication of pending signals that might
2134          * be seen by the filesystem code called to write the core file.
2135          */
2136         clear_thread_flag(TIF_SIGPENDING);
2137
2138         ispipe = format_corename(&cn, signr);
2139
2140         if (ispipe) {
2141                 int dump_count;
2142                 char **helper_argv;
2143
2144                 if (ispipe < 0) {
2145                         printk(KERN_WARNING "format_corename failed\n");
2146                         printk(KERN_WARNING "Aborting core\n");
2147                         goto fail_corename;
2148                 }
2149
2150                 if (cprm.limit == 1) {
2151                         /*
2152                          * Normally core limits are irrelevant to pipes, since
2153                          * we're not writing to the file system, but we use
2154                          * cprm.limit of 1 here as a speacial value. Any
2155                          * non-1 limit gets set to RLIM_INFINITY below, but
2156                          * a limit of 0 skips the dump.  This is a consistent
2157                          * way to catch recursive crashes.  We can still crash
2158                          * if the core_pattern binary sets RLIM_CORE =  !1
2159                          * but it runs as root, and can do lots of stupid things
2160                          * Note that we use task_tgid_vnr here to grab the pid
2161                          * of the process group leader.  That way we get the
2162                          * right pid if a thread in a multi-threaded
2163                          * core_pattern process dies.
2164                          */
2165                         printk(KERN_WARNING
2166                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2167                                 task_tgid_vnr(current), current->comm);
2168                         printk(KERN_WARNING "Aborting core\n");
2169                         goto fail_unlock;
2170                 }
2171                 cprm.limit = RLIM_INFINITY;
2172
2173                 dump_count = atomic_inc_return(&core_dump_count);
2174                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2175                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2176                                task_tgid_vnr(current), current->comm);
2177                         printk(KERN_WARNING "Skipping core dump\n");
2178                         goto fail_dropcount;
2179                 }
2180
2181                 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2182                 if (!helper_argv) {
2183                         printk(KERN_WARNING "%s failed to allocate memory\n",
2184                                __func__);
2185                         goto fail_dropcount;
2186                 }
2187
2188                 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2189                                         NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2190                                         NULL, &cprm);
2191                 argv_free(helper_argv);
2192                 if (retval) {
2193                         printk(KERN_INFO "Core dump to %s pipe failed\n",
2194                                cn.corename);
2195                         goto close_fail;
2196                 }
2197         } else {
2198                 struct inode *inode;
2199
2200                 if (cprm.limit < binfmt->min_coredump)
2201                         goto fail_unlock;
2202
2203                 cprm.file = filp_open(cn.corename,
2204                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2205                                  0600);
2206                 if (IS_ERR(cprm.file))
2207                         goto fail_unlock;
2208
2209                 inode = cprm.file->f_path.dentry->d_inode;
2210                 if (inode->i_nlink > 1)
2211                         goto close_fail;
2212                 if (d_unhashed(cprm.file->f_path.dentry))
2213                         goto close_fail;
2214                 /*
2215                  * AK: actually i see no reason to not allow this for named
2216                  * pipes etc, but keep the previous behaviour for now.
2217                  */
2218                 if (!S_ISREG(inode->i_mode))
2219                         goto close_fail;
2220                 /*
2221                  * Dont allow local users get cute and trick others to coredump
2222                  * into their pre-created files.
2223                  */
2224                 if (inode->i_uid != current_fsuid())
2225                         goto close_fail;
2226                 if (!cprm.file->f_op || !cprm.file->f_op->write)
2227                         goto close_fail;
2228                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2229                         goto close_fail;
2230         }
2231
2232         retval = binfmt->core_dump(&cprm);
2233         if (retval)
2234                 current->signal->group_exit_code |= 0x80;
2235
2236         if (ispipe && core_pipe_limit)
2237                 wait_for_dump_helpers(cprm.file);
2238 close_fail:
2239         if (cprm.file)
2240                 filp_close(cprm.file, NULL);
2241 fail_dropcount:
2242         if (ispipe)
2243                 atomic_dec(&core_dump_count);
2244 fail_unlock:
2245         kfree(cn.corename);
2246 fail_corename:
2247         coredump_finish(mm);
2248         revert_creds(old_cred);
2249 fail_creds:
2250         put_cred(cred);
2251 fail:
2252         return;
2253 }
2254
2255 /*
2256  * Core dumping helper functions.  These are the only things you should
2257  * do on a core-file: use only these functions to write out all the
2258  * necessary info.
2259  */
2260 int dump_write(struct file *file, const void *addr, int nr)
2261 {
2262         return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2263 }
2264 EXPORT_SYMBOL(dump_write);
2265
2266 int dump_seek(struct file *file, loff_t off)
2267 {
2268         int ret = 1;
2269
2270         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2271                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2272                         return 0;
2273         } else {
2274                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2275
2276                 if (!buf)
2277                         return 0;
2278                 while (off > 0) {
2279                         unsigned long n = off;
2280
2281                         if (n > PAGE_SIZE)
2282                                 n = PAGE_SIZE;
2283                         if (!dump_write(file, buf, n)) {
2284                                 ret = 0;
2285                                 break;
2286                         }
2287                         off -= n;
2288                 }
2289                 free_page((unsigned long)buf);
2290         }
2291         return ret;
2292 }
2293 EXPORT_SYMBOL(dump_seek);