core_pattern: fix truncation by core_pattern handler with long parameters
[linux-2.6.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/proc_fs.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/tsacct_kern.h>
50 #include <linux/cn_proc.h>
51 #include <linux/audit.h>
52 #include <linux/tracehook.h>
53 #include <linux/kmod.h>
54 #include <linux/fsnotify.h>
55 #include <linux/fs_struct.h>
56 #include <linux/pipe_fs_i.h>
57 #include <linux/oom.h>
58
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
119         if (IS_ERR(tmp))
120                 goto out;
121
122         file = do_filp_open(AT_FDCWD, tmp,
123                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
124                                 MAY_READ | MAY_EXEC | MAY_OPEN);
125         putname(tmp);
126         error = PTR_ERR(file);
127         if (IS_ERR(file))
128                 goto out;
129
130         error = -EINVAL;
131         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
132                 goto exit;
133
134         error = -EACCES;
135         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
136                 goto exit;
137
138         fsnotify_open(file);
139
140         error = -ENOEXEC;
141         if(file->f_op) {
142                 struct linux_binfmt * fmt;
143
144                 read_lock(&binfmt_lock);
145                 list_for_each_entry(fmt, &formats, lh) {
146                         if (!fmt->load_shlib)
147                                 continue;
148                         if (!try_module_get(fmt->module))
149                                 continue;
150                         read_unlock(&binfmt_lock);
151                         error = fmt->load_shlib(file);
152                         read_lock(&binfmt_lock);
153                         put_binfmt(fmt);
154                         if (error != -ENOEXEC)
155                                 break;
156                 }
157                 read_unlock(&binfmt_lock);
158         }
159 exit:
160         fput(file);
161 out:
162         return error;
163 }
164
165 #ifdef CONFIG_MMU
166
167 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
168                 int write)
169 {
170         struct page *page;
171         int ret;
172
173 #ifdef CONFIG_STACK_GROWSUP
174         if (write) {
175                 ret = expand_stack_downwards(bprm->vma, pos);
176                 if (ret < 0)
177                         return NULL;
178         }
179 #endif
180         ret = get_user_pages(current, bprm->mm, pos,
181                         1, write, 1, &page, NULL);
182         if (ret <= 0)
183                 return NULL;
184
185         if (write) {
186                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
187                 struct rlimit *rlim;
188
189                 /*
190                  * We've historically supported up to 32 pages (ARG_MAX)
191                  * of argument strings even with small stacks
192                  */
193                 if (size <= ARG_MAX)
194                         return page;
195
196                 /*
197                  * Limit to 1/4-th the stack size for the argv+env strings.
198                  * This ensures that:
199                  *  - the remaining binfmt code will not run out of stack space,
200                  *  - the program will have a reasonable amount of stack left
201                  *    to work from.
202                  */
203                 rlim = current->signal->rlim;
204                 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
205                         put_page(page);
206                         return NULL;
207                 }
208         }
209
210         return page;
211 }
212
213 static void put_arg_page(struct page *page)
214 {
215         put_page(page);
216 }
217
218 static void free_arg_page(struct linux_binprm *bprm, int i)
219 {
220 }
221
222 static void free_arg_pages(struct linux_binprm *bprm)
223 {
224 }
225
226 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
227                 struct page *page)
228 {
229         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
230 }
231
232 static int __bprm_mm_init(struct linux_binprm *bprm)
233 {
234         int err;
235         struct vm_area_struct *vma = NULL;
236         struct mm_struct *mm = bprm->mm;
237
238         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
239         if (!vma)
240                 return -ENOMEM;
241
242         down_write(&mm->mmap_sem);
243         vma->vm_mm = mm;
244
245         /*
246          * Place the stack at the largest stack address the architecture
247          * supports. Later, we'll move this to an appropriate place. We don't
248          * use STACK_TOP because that can depend on attributes which aren't
249          * configured yet.
250          */
251         BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
252         vma->vm_end = STACK_TOP_MAX;
253         vma->vm_start = vma->vm_end - PAGE_SIZE;
254         vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
255         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
256         INIT_LIST_HEAD(&vma->anon_vma_chain);
257         err = insert_vm_struct(mm, vma);
258         if (err)
259                 goto err;
260
261         mm->stack_vm = mm->total_vm = 1;
262         up_write(&mm->mmap_sem);
263         bprm->p = vma->vm_end - sizeof(void *);
264         return 0;
265 err:
266         up_write(&mm->mmap_sem);
267         bprm->vma = NULL;
268         kmem_cache_free(vm_area_cachep, vma);
269         return err;
270 }
271
272 static bool valid_arg_len(struct linux_binprm *bprm, long len)
273 {
274         return len <= MAX_ARG_STRLEN;
275 }
276
277 #else
278
279 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
280                 int write)
281 {
282         struct page *page;
283
284         page = bprm->page[pos / PAGE_SIZE];
285         if (!page && write) {
286                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
287                 if (!page)
288                         return NULL;
289                 bprm->page[pos / PAGE_SIZE] = page;
290         }
291
292         return page;
293 }
294
295 static void put_arg_page(struct page *page)
296 {
297 }
298
299 static void free_arg_page(struct linux_binprm *bprm, int i)
300 {
301         if (bprm->page[i]) {
302                 __free_page(bprm->page[i]);
303                 bprm->page[i] = NULL;
304         }
305 }
306
307 static void free_arg_pages(struct linux_binprm *bprm)
308 {
309         int i;
310
311         for (i = 0; i < MAX_ARG_PAGES; i++)
312                 free_arg_page(bprm, i);
313 }
314
315 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
316                 struct page *page)
317 {
318 }
319
320 static int __bprm_mm_init(struct linux_binprm *bprm)
321 {
322         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
323         return 0;
324 }
325
326 static bool valid_arg_len(struct linux_binprm *bprm, long len)
327 {
328         return len <= bprm->p;
329 }
330
331 #endif /* CONFIG_MMU */
332
333 /*
334  * Create a new mm_struct and populate it with a temporary stack
335  * vm_area_struct.  We don't have enough context at this point to set the stack
336  * flags, permissions, and offset, so we use temporary values.  We'll update
337  * them later in setup_arg_pages().
338  */
339 int bprm_mm_init(struct linux_binprm *bprm)
340 {
341         int err;
342         struct mm_struct *mm = NULL;
343
344         bprm->mm = mm = mm_alloc();
345         err = -ENOMEM;
346         if (!mm)
347                 goto err;
348
349         err = init_new_context(current, mm);
350         if (err)
351                 goto err;
352
353         err = __bprm_mm_init(bprm);
354         if (err)
355                 goto err;
356
357         return 0;
358
359 err:
360         if (mm) {
361                 bprm->mm = NULL;
362                 mmdrop(mm);
363         }
364
365         return err;
366 }
367
368 /*
369  * count() counts the number of strings in array ARGV.
370  */
371 static int count(const char __user * const __user * argv, int max)
372 {
373         int i = 0;
374
375         if (argv != NULL) {
376                 for (;;) {
377                         const char __user * p;
378
379                         if (get_user(p, argv))
380                                 return -EFAULT;
381                         if (!p)
382                                 break;
383                         argv++;
384                         if (i++ >= max)
385                                 return -E2BIG;
386
387                         if (fatal_signal_pending(current))
388                                 return -ERESTARTNOHAND;
389                         cond_resched();
390                 }
391         }
392         return i;
393 }
394
395 /*
396  * 'copy_strings()' copies argument/environment strings from the old
397  * processes's memory to the new process's stack.  The call to get_user_pages()
398  * ensures the destination page is created and not swapped out.
399  */
400 static int copy_strings(int argc, const char __user *const __user *argv,
401                         struct linux_binprm *bprm)
402 {
403         struct page *kmapped_page = NULL;
404         char *kaddr = NULL;
405         unsigned long kpos = 0;
406         int ret;
407
408         while (argc-- > 0) {
409                 const char __user *str;
410                 int len;
411                 unsigned long pos;
412
413                 if (get_user(str, argv+argc) ||
414                                 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
415                         ret = -EFAULT;
416                         goto out;
417                 }
418
419                 if (!valid_arg_len(bprm, len)) {
420                         ret = -E2BIG;
421                         goto out;
422                 }
423
424                 /* We're going to work our way backwords. */
425                 pos = bprm->p;
426                 str += len;
427                 bprm->p -= len;
428
429                 while (len > 0) {
430                         int offset, bytes_to_copy;
431
432                         if (fatal_signal_pending(current)) {
433                                 ret = -ERESTARTNOHAND;
434                                 goto out;
435                         }
436                         cond_resched();
437
438                         offset = pos % PAGE_SIZE;
439                         if (offset == 0)
440                                 offset = PAGE_SIZE;
441
442                         bytes_to_copy = offset;
443                         if (bytes_to_copy > len)
444                                 bytes_to_copy = len;
445
446                         offset -= bytes_to_copy;
447                         pos -= bytes_to_copy;
448                         str -= bytes_to_copy;
449                         len -= bytes_to_copy;
450
451                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
452                                 struct page *page;
453
454                                 page = get_arg_page(bprm, pos, 1);
455                                 if (!page) {
456                                         ret = -E2BIG;
457                                         goto out;
458                                 }
459
460                                 if (kmapped_page) {
461                                         flush_kernel_dcache_page(kmapped_page);
462                                         kunmap(kmapped_page);
463                                         put_arg_page(kmapped_page);
464                                 }
465                                 kmapped_page = page;
466                                 kaddr = kmap(kmapped_page);
467                                 kpos = pos & PAGE_MASK;
468                                 flush_arg_page(bprm, kpos, kmapped_page);
469                         }
470                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
471                                 ret = -EFAULT;
472                                 goto out;
473                         }
474                 }
475         }
476         ret = 0;
477 out:
478         if (kmapped_page) {
479                 flush_kernel_dcache_page(kmapped_page);
480                 kunmap(kmapped_page);
481                 put_arg_page(kmapped_page);
482         }
483         return ret;
484 }
485
486 /*
487  * Like copy_strings, but get argv and its values from kernel memory.
488  */
489 int copy_strings_kernel(int argc, const char *const *argv,
490                         struct linux_binprm *bprm)
491 {
492         int r;
493         mm_segment_t oldfs = get_fs();
494         set_fs(KERNEL_DS);
495         r = copy_strings(argc, (const char __user *const  __user *)argv, bprm);
496         set_fs(oldfs);
497         return r;
498 }
499 EXPORT_SYMBOL(copy_strings_kernel);
500
501 #ifdef CONFIG_MMU
502
503 /*
504  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
505  * the binfmt code determines where the new stack should reside, we shift it to
506  * its final location.  The process proceeds as follows:
507  *
508  * 1) Use shift to calculate the new vma endpoints.
509  * 2) Extend vma to cover both the old and new ranges.  This ensures the
510  *    arguments passed to subsequent functions are consistent.
511  * 3) Move vma's page tables to the new range.
512  * 4) Free up any cleared pgd range.
513  * 5) Shrink the vma to cover only the new range.
514  */
515 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
516 {
517         struct mm_struct *mm = vma->vm_mm;
518         unsigned long old_start = vma->vm_start;
519         unsigned long old_end = vma->vm_end;
520         unsigned long length = old_end - old_start;
521         unsigned long new_start = old_start - shift;
522         unsigned long new_end = old_end - shift;
523         struct mmu_gather *tlb;
524
525         BUG_ON(new_start > new_end);
526
527         /*
528          * ensure there are no vmas between where we want to go
529          * and where we are
530          */
531         if (vma != find_vma(mm, new_start))
532                 return -EFAULT;
533
534         /*
535          * cover the whole range: [new_start, old_end)
536          */
537         if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
538                 return -ENOMEM;
539
540         /*
541          * move the page tables downwards, on failure we rely on
542          * process cleanup to remove whatever mess we made.
543          */
544         if (length != move_page_tables(vma, old_start,
545                                        vma, new_start, length))
546                 return -ENOMEM;
547
548         lru_add_drain();
549         tlb = tlb_gather_mmu(mm, 0);
550         if (new_end > old_start) {
551                 /*
552                  * when the old and new regions overlap clear from new_end.
553                  */
554                 free_pgd_range(tlb, new_end, old_end, new_end,
555                         vma->vm_next ? vma->vm_next->vm_start : 0);
556         } else {
557                 /*
558                  * otherwise, clean from old_start; this is done to not touch
559                  * the address space in [new_end, old_start) some architectures
560                  * have constraints on va-space that make this illegal (IA64) -
561                  * for the others its just a little faster.
562                  */
563                 free_pgd_range(tlb, old_start, old_end, new_end,
564                         vma->vm_next ? vma->vm_next->vm_start : 0);
565         }
566         tlb_finish_mmu(tlb, new_end, old_end);
567
568         /*
569          * Shrink the vma to just the new range.  Always succeeds.
570          */
571         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
572
573         return 0;
574 }
575
576 /*
577  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
578  * the stack is optionally relocated, and some extra space is added.
579  */
580 int setup_arg_pages(struct linux_binprm *bprm,
581                     unsigned long stack_top,
582                     int executable_stack)
583 {
584         unsigned long ret;
585         unsigned long stack_shift;
586         struct mm_struct *mm = current->mm;
587         struct vm_area_struct *vma = bprm->vma;
588         struct vm_area_struct *prev = NULL;
589         unsigned long vm_flags;
590         unsigned long stack_base;
591         unsigned long stack_size;
592         unsigned long stack_expand;
593         unsigned long rlim_stack;
594
595 #ifdef CONFIG_STACK_GROWSUP
596         /* Limit stack size to 1GB */
597         stack_base = rlimit_max(RLIMIT_STACK);
598         if (stack_base > (1 << 30))
599                 stack_base = 1 << 30;
600
601         /* Make sure we didn't let the argument array grow too large. */
602         if (vma->vm_end - vma->vm_start > stack_base)
603                 return -ENOMEM;
604
605         stack_base = PAGE_ALIGN(stack_top - stack_base);
606
607         stack_shift = vma->vm_start - stack_base;
608         mm->arg_start = bprm->p - stack_shift;
609         bprm->p = vma->vm_end - stack_shift;
610 #else
611         stack_top = arch_align_stack(stack_top);
612         stack_top = PAGE_ALIGN(stack_top);
613
614         if (unlikely(stack_top < mmap_min_addr) ||
615             unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
616                 return -ENOMEM;
617
618         stack_shift = vma->vm_end - stack_top;
619
620         bprm->p -= stack_shift;
621         mm->arg_start = bprm->p;
622 #endif
623
624         if (bprm->loader)
625                 bprm->loader -= stack_shift;
626         bprm->exec -= stack_shift;
627
628         down_write(&mm->mmap_sem);
629         vm_flags = VM_STACK_FLAGS;
630
631         /*
632          * Adjust stack execute permissions; explicitly enable for
633          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
634          * (arch default) otherwise.
635          */
636         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
637                 vm_flags |= VM_EXEC;
638         else if (executable_stack == EXSTACK_DISABLE_X)
639                 vm_flags &= ~VM_EXEC;
640         vm_flags |= mm->def_flags;
641         vm_flags |= VM_STACK_INCOMPLETE_SETUP;
642
643         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
644                         vm_flags);
645         if (ret)
646                 goto out_unlock;
647         BUG_ON(prev != vma);
648
649         /* Move stack pages down in memory. */
650         if (stack_shift) {
651                 ret = shift_arg_pages(vma, stack_shift);
652                 if (ret)
653                         goto out_unlock;
654         }
655
656         /* mprotect_fixup is overkill to remove the temporary stack flags */
657         vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
658
659         stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
660         stack_size = vma->vm_end - vma->vm_start;
661         /*
662          * Align this down to a page boundary as expand_stack
663          * will align it up.
664          */
665         rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
666 #ifdef CONFIG_STACK_GROWSUP
667         if (stack_size + stack_expand > rlim_stack)
668                 stack_base = vma->vm_start + rlim_stack;
669         else
670                 stack_base = vma->vm_end + stack_expand;
671 #else
672         if (stack_size + stack_expand > rlim_stack)
673                 stack_base = vma->vm_end - rlim_stack;
674         else
675                 stack_base = vma->vm_start - stack_expand;
676 #endif
677         current->mm->start_stack = bprm->p;
678         ret = expand_stack(vma, stack_base);
679         if (ret)
680                 ret = -EFAULT;
681
682 out_unlock:
683         up_write(&mm->mmap_sem);
684         return ret;
685 }
686 EXPORT_SYMBOL(setup_arg_pages);
687
688 #endif /* CONFIG_MMU */
689
690 struct file *open_exec(const char *name)
691 {
692         struct file *file;
693         int err;
694
695         file = do_filp_open(AT_FDCWD, name,
696                                 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
697                                 MAY_EXEC | MAY_OPEN);
698         if (IS_ERR(file))
699                 goto out;
700
701         err = -EACCES;
702         if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
703                 goto exit;
704
705         if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
706                 goto exit;
707
708         fsnotify_open(file);
709
710         err = deny_write_access(file);
711         if (err)
712                 goto exit;
713
714 out:
715         return file;
716
717 exit:
718         fput(file);
719         return ERR_PTR(err);
720 }
721 EXPORT_SYMBOL(open_exec);
722
723 int kernel_read(struct file *file, loff_t offset,
724                 char *addr, unsigned long count)
725 {
726         mm_segment_t old_fs;
727         loff_t pos = offset;
728         int result;
729
730         old_fs = get_fs();
731         set_fs(get_ds());
732         /* The cast to a user pointer is valid due to the set_fs() */
733         result = vfs_read(file, (void __user *)addr, count, &pos);
734         set_fs(old_fs);
735         return result;
736 }
737
738 EXPORT_SYMBOL(kernel_read);
739
740 static int exec_mmap(struct mm_struct *mm)
741 {
742         struct task_struct *tsk;
743         struct mm_struct * old_mm, *active_mm;
744
745         /* Notify parent that we're no longer interested in the old VM */
746         tsk = current;
747         old_mm = current->mm;
748         sync_mm_rss(tsk, old_mm);
749         mm_release(tsk, old_mm);
750
751         if (old_mm) {
752                 /*
753                  * Make sure that if there is a core dump in progress
754                  * for the old mm, we get out and die instead of going
755                  * through with the exec.  We must hold mmap_sem around
756                  * checking core_state and changing tsk->mm.
757                  */
758                 down_read(&old_mm->mmap_sem);
759                 if (unlikely(old_mm->core_state)) {
760                         up_read(&old_mm->mmap_sem);
761                         return -EINTR;
762                 }
763         }
764         task_lock(tsk);
765         active_mm = tsk->active_mm;
766         tsk->mm = mm;
767         tsk->active_mm = mm;
768         activate_mm(active_mm, mm);
769         if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
770                 atomic_dec(&old_mm->oom_disable_count);
771                 atomic_inc(&tsk->mm->oom_disable_count);
772         }
773         task_unlock(tsk);
774         arch_pick_mmap_layout(mm);
775         if (old_mm) {
776                 up_read(&old_mm->mmap_sem);
777                 BUG_ON(active_mm != old_mm);
778                 mm_update_next_owner(old_mm);
779                 mmput(old_mm);
780                 return 0;
781         }
782         mmdrop(active_mm);
783         return 0;
784 }
785
786 /*
787  * This function makes sure the current process has its own signal table,
788  * so that flush_signal_handlers can later reset the handlers without
789  * disturbing other processes.  (Other processes might share the signal
790  * table via the CLONE_SIGHAND option to clone().)
791  */
792 static int de_thread(struct task_struct *tsk)
793 {
794         struct signal_struct *sig = tsk->signal;
795         struct sighand_struct *oldsighand = tsk->sighand;
796         spinlock_t *lock = &oldsighand->siglock;
797
798         if (thread_group_empty(tsk))
799                 goto no_thread_group;
800
801         /*
802          * Kill all other threads in the thread group.
803          */
804         spin_lock_irq(lock);
805         if (signal_group_exit(sig)) {
806                 /*
807                  * Another group action in progress, just
808                  * return so that the signal is processed.
809                  */
810                 spin_unlock_irq(lock);
811                 return -EAGAIN;
812         }
813
814         sig->group_exit_task = tsk;
815         sig->notify_count = zap_other_threads(tsk);
816         if (!thread_group_leader(tsk))
817                 sig->notify_count--;
818
819         while (sig->notify_count) {
820                 __set_current_state(TASK_UNINTERRUPTIBLE);
821                 spin_unlock_irq(lock);
822                 schedule();
823                 spin_lock_irq(lock);
824         }
825         spin_unlock_irq(lock);
826
827         /*
828          * At this point all other threads have exited, all we have to
829          * do is to wait for the thread group leader to become inactive,
830          * and to assume its PID:
831          */
832         if (!thread_group_leader(tsk)) {
833                 struct task_struct *leader = tsk->group_leader;
834
835                 sig->notify_count = -1; /* for exit_notify() */
836                 for (;;) {
837                         write_lock_irq(&tasklist_lock);
838                         if (likely(leader->exit_state))
839                                 break;
840                         __set_current_state(TASK_UNINTERRUPTIBLE);
841                         write_unlock_irq(&tasklist_lock);
842                         schedule();
843                 }
844
845                 /*
846                  * The only record we have of the real-time age of a
847                  * process, regardless of execs it's done, is start_time.
848                  * All the past CPU time is accumulated in signal_struct
849                  * from sister threads now dead.  But in this non-leader
850                  * exec, nothing survives from the original leader thread,
851                  * whose birth marks the true age of this process now.
852                  * When we take on its identity by switching to its PID, we
853                  * also take its birthdate (always earlier than our own).
854                  */
855                 tsk->start_time = leader->start_time;
856
857                 BUG_ON(!same_thread_group(leader, tsk));
858                 BUG_ON(has_group_leader_pid(tsk));
859                 /*
860                  * An exec() starts a new thread group with the
861                  * TGID of the previous thread group. Rehash the
862                  * two threads with a switched PID, and release
863                  * the former thread group leader:
864                  */
865
866                 /* Become a process group leader with the old leader's pid.
867                  * The old leader becomes a thread of the this thread group.
868                  * Note: The old leader also uses this pid until release_task
869                  *       is called.  Odd but simple and correct.
870                  */
871                 detach_pid(tsk, PIDTYPE_PID);
872                 tsk->pid = leader->pid;
873                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
874                 transfer_pid(leader, tsk, PIDTYPE_PGID);
875                 transfer_pid(leader, tsk, PIDTYPE_SID);
876
877                 list_replace_rcu(&leader->tasks, &tsk->tasks);
878                 list_replace_init(&leader->sibling, &tsk->sibling);
879
880                 tsk->group_leader = tsk;
881                 leader->group_leader = tsk;
882
883                 tsk->exit_signal = SIGCHLD;
884
885                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
886                 leader->exit_state = EXIT_DEAD;
887                 write_unlock_irq(&tasklist_lock);
888
889                 release_task(leader);
890         }
891
892         sig->group_exit_task = NULL;
893         sig->notify_count = 0;
894
895 no_thread_group:
896         if (current->mm)
897                 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
898
899         exit_itimers(sig);
900         flush_itimer_signals();
901
902         if (atomic_read(&oldsighand->count) != 1) {
903                 struct sighand_struct *newsighand;
904                 /*
905                  * This ->sighand is shared with the CLONE_SIGHAND
906                  * but not CLONE_THREAD task, switch to the new one.
907                  */
908                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
909                 if (!newsighand)
910                         return -ENOMEM;
911
912                 atomic_set(&newsighand->count, 1);
913                 memcpy(newsighand->action, oldsighand->action,
914                        sizeof(newsighand->action));
915
916                 write_lock_irq(&tasklist_lock);
917                 spin_lock(&oldsighand->siglock);
918                 rcu_assign_pointer(tsk->sighand, newsighand);
919                 spin_unlock(&oldsighand->siglock);
920                 write_unlock_irq(&tasklist_lock);
921
922                 __cleanup_sighand(oldsighand);
923         }
924
925         BUG_ON(!thread_group_leader(tsk));
926         return 0;
927 }
928
929 /*
930  * These functions flushes out all traces of the currently running executable
931  * so that a new one can be started
932  */
933 static void flush_old_files(struct files_struct * files)
934 {
935         long j = -1;
936         struct fdtable *fdt;
937
938         spin_lock(&files->file_lock);
939         for (;;) {
940                 unsigned long set, i;
941
942                 j++;
943                 i = j * __NFDBITS;
944                 fdt = files_fdtable(files);
945                 if (i >= fdt->max_fds)
946                         break;
947                 set = fdt->close_on_exec->fds_bits[j];
948                 if (!set)
949                         continue;
950                 fdt->close_on_exec->fds_bits[j] = 0;
951                 spin_unlock(&files->file_lock);
952                 for ( ; set ; i++,set >>= 1) {
953                         if (set & 1) {
954                                 sys_close(i);
955                         }
956                 }
957                 spin_lock(&files->file_lock);
958
959         }
960         spin_unlock(&files->file_lock);
961 }
962
963 char *get_task_comm(char *buf, struct task_struct *tsk)
964 {
965         /* buf must be at least sizeof(tsk->comm) in size */
966         task_lock(tsk);
967         strncpy(buf, tsk->comm, sizeof(tsk->comm));
968         task_unlock(tsk);
969         return buf;
970 }
971
972 void set_task_comm(struct task_struct *tsk, char *buf)
973 {
974         task_lock(tsk);
975
976         /*
977          * Threads may access current->comm without holding
978          * the task lock, so write the string carefully.
979          * Readers without a lock may see incomplete new
980          * names but are safe from non-terminating string reads.
981          */
982         memset(tsk->comm, 0, TASK_COMM_LEN);
983         wmb();
984         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
985         task_unlock(tsk);
986         perf_event_comm(tsk);
987 }
988
989 int flush_old_exec(struct linux_binprm * bprm)
990 {
991         int retval;
992
993         /*
994          * Make sure we have a private signal table and that
995          * we are unassociated from the previous thread group.
996          */
997         retval = de_thread(current);
998         if (retval)
999                 goto out;
1000
1001         set_mm_exe_file(bprm->mm, bprm->file);
1002
1003         /*
1004          * Release all of the old mmap stuff
1005          */
1006         retval = exec_mmap(bprm->mm);
1007         if (retval)
1008                 goto out;
1009
1010         bprm->mm = NULL;                /* We're using it now */
1011
1012         current->flags &= ~PF_RANDOMIZE;
1013         flush_thread();
1014         current->personality &= ~bprm->per_clear;
1015
1016         return 0;
1017
1018 out:
1019         return retval;
1020 }
1021 EXPORT_SYMBOL(flush_old_exec);
1022
1023 void setup_new_exec(struct linux_binprm * bprm)
1024 {
1025         int i, ch;
1026         const char *name;
1027         char tcomm[sizeof(current->comm)];
1028
1029         arch_pick_mmap_layout(current->mm);
1030
1031         /* This is the point of no return */
1032         current->sas_ss_sp = current->sas_ss_size = 0;
1033
1034         if (current_euid() == current_uid() && current_egid() == current_gid())
1035                 set_dumpable(current->mm, 1);
1036         else
1037                 set_dumpable(current->mm, suid_dumpable);
1038
1039         name = bprm->filename;
1040
1041         /* Copies the binary name from after last slash */
1042         for (i=0; (ch = *(name++)) != '\0';) {
1043                 if (ch == '/')
1044                         i = 0; /* overwrite what we wrote */
1045                 else
1046                         if (i < (sizeof(tcomm) - 1))
1047                                 tcomm[i++] = ch;
1048         }
1049         tcomm[i] = '\0';
1050         set_task_comm(current, tcomm);
1051
1052         /* Set the new mm task size. We have to do that late because it may
1053          * depend on TIF_32BIT which is only updated in flush_thread() on
1054          * some architectures like powerpc
1055          */
1056         current->mm->task_size = TASK_SIZE;
1057
1058         /* install the new credentials */
1059         if (bprm->cred->uid != current_euid() ||
1060             bprm->cred->gid != current_egid()) {
1061                 current->pdeath_signal = 0;
1062         } else if (file_permission(bprm->file, MAY_READ) ||
1063                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1064                 set_dumpable(current->mm, suid_dumpable);
1065         }
1066
1067         /*
1068          * Flush performance counters when crossing a
1069          * security domain:
1070          */
1071         if (!get_dumpable(current->mm))
1072                 perf_event_exit_task(current);
1073
1074         /* An exec changes our domain. We are no longer part of the thread
1075            group */
1076
1077         current->self_exec_id++;
1078                         
1079         flush_signal_handlers(current, 0);
1080         flush_old_files(current->files);
1081 }
1082 EXPORT_SYMBOL(setup_new_exec);
1083
1084 /*
1085  * Prepare credentials and lock ->cred_guard_mutex.
1086  * install_exec_creds() commits the new creds and drops the lock.
1087  * Or, if exec fails before, free_bprm() should release ->cred and
1088  * and unlock.
1089  */
1090 int prepare_bprm_creds(struct linux_binprm *bprm)
1091 {
1092         if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1093                 return -ERESTARTNOINTR;
1094
1095         bprm->cred = prepare_exec_creds();
1096         if (likely(bprm->cred))
1097                 return 0;
1098
1099         mutex_unlock(&current->signal->cred_guard_mutex);
1100         return -ENOMEM;
1101 }
1102
1103 void free_bprm(struct linux_binprm *bprm)
1104 {
1105         free_arg_pages(bprm);
1106         if (bprm->cred) {
1107                 mutex_unlock(&current->signal->cred_guard_mutex);
1108                 abort_creds(bprm->cred);
1109         }
1110         kfree(bprm);
1111 }
1112
1113 /*
1114  * install the new credentials for this executable
1115  */
1116 void install_exec_creds(struct linux_binprm *bprm)
1117 {
1118         security_bprm_committing_creds(bprm);
1119
1120         commit_creds(bprm->cred);
1121         bprm->cred = NULL;
1122         /*
1123          * cred_guard_mutex must be held at least to this point to prevent
1124          * ptrace_attach() from altering our determination of the task's
1125          * credentials; any time after this it may be unlocked.
1126          */
1127         security_bprm_committed_creds(bprm);
1128         mutex_unlock(&current->signal->cred_guard_mutex);
1129 }
1130 EXPORT_SYMBOL(install_exec_creds);
1131
1132 /*
1133  * determine how safe it is to execute the proposed program
1134  * - the caller must hold ->cred_guard_mutex to protect against
1135  *   PTRACE_ATTACH
1136  */
1137 int check_unsafe_exec(struct linux_binprm *bprm)
1138 {
1139         struct task_struct *p = current, *t;
1140         unsigned n_fs;
1141         int res = 0;
1142
1143         bprm->unsafe = tracehook_unsafe_exec(p);
1144
1145         n_fs = 1;
1146         spin_lock(&p->fs->lock);
1147         rcu_read_lock();
1148         for (t = next_thread(p); t != p; t = next_thread(t)) {
1149                 if (t->fs == p->fs)
1150                         n_fs++;
1151         }
1152         rcu_read_unlock();
1153
1154         if (p->fs->users > n_fs) {
1155                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1156         } else {
1157                 res = -EAGAIN;
1158                 if (!p->fs->in_exec) {
1159                         p->fs->in_exec = 1;
1160                         res = 1;
1161                 }
1162         }
1163         spin_unlock(&p->fs->lock);
1164
1165         return res;
1166 }
1167
1168 /* 
1169  * Fill the binprm structure from the inode. 
1170  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1171  *
1172  * This may be called multiple times for binary chains (scripts for example).
1173  */
1174 int prepare_binprm(struct linux_binprm *bprm)
1175 {
1176         umode_t mode;
1177         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1178         int retval;
1179
1180         mode = inode->i_mode;
1181         if (bprm->file->f_op == NULL)
1182                 return -EACCES;
1183
1184         /* clear any previous set[ug]id data from a previous binary */
1185         bprm->cred->euid = current_euid();
1186         bprm->cred->egid = current_egid();
1187
1188         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1189                 /* Set-uid? */
1190                 if (mode & S_ISUID) {
1191                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1192                         bprm->cred->euid = inode->i_uid;
1193                 }
1194
1195                 /* Set-gid? */
1196                 /*
1197                  * If setgid is set but no group execute bit then this
1198                  * is a candidate for mandatory locking, not a setgid
1199                  * executable.
1200                  */
1201                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1202                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1203                         bprm->cred->egid = inode->i_gid;
1204                 }
1205         }
1206
1207         /* fill in binprm security blob */
1208         retval = security_bprm_set_creds(bprm);
1209         if (retval)
1210                 return retval;
1211         bprm->cred_prepared = 1;
1212
1213         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1214         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1215 }
1216
1217 EXPORT_SYMBOL(prepare_binprm);
1218
1219 /*
1220  * Arguments are '\0' separated strings found at the location bprm->p
1221  * points to; chop off the first by relocating brpm->p to right after
1222  * the first '\0' encountered.
1223  */
1224 int remove_arg_zero(struct linux_binprm *bprm)
1225 {
1226         int ret = 0;
1227         unsigned long offset;
1228         char *kaddr;
1229         struct page *page;
1230
1231         if (!bprm->argc)
1232                 return 0;
1233
1234         do {
1235                 offset = bprm->p & ~PAGE_MASK;
1236                 page = get_arg_page(bprm, bprm->p, 0);
1237                 if (!page) {
1238                         ret = -EFAULT;
1239                         goto out;
1240                 }
1241                 kaddr = kmap_atomic(page, KM_USER0);
1242
1243                 for (; offset < PAGE_SIZE && kaddr[offset];
1244                                 offset++, bprm->p++)
1245                         ;
1246
1247                 kunmap_atomic(kaddr, KM_USER0);
1248                 put_arg_page(page);
1249
1250                 if (offset == PAGE_SIZE)
1251                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1252         } while (offset == PAGE_SIZE);
1253
1254         bprm->p++;
1255         bprm->argc--;
1256         ret = 0;
1257
1258 out:
1259         return ret;
1260 }
1261 EXPORT_SYMBOL(remove_arg_zero);
1262
1263 /*
1264  * cycle the list of binary formats handler, until one recognizes the image
1265  */
1266 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1267 {
1268         unsigned int depth = bprm->recursion_depth;
1269         int try,retval;
1270         struct linux_binfmt *fmt;
1271
1272         retval = security_bprm_check(bprm);
1273         if (retval)
1274                 return retval;
1275
1276         /* kernel module loader fixup */
1277         /* so we don't try to load run modprobe in kernel space. */
1278         set_fs(USER_DS);
1279
1280         retval = audit_bprm(bprm);
1281         if (retval)
1282                 return retval;
1283
1284         retval = -ENOENT;
1285         for (try=0; try<2; try++) {
1286                 read_lock(&binfmt_lock);
1287                 list_for_each_entry(fmt, &formats, lh) {
1288                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1289                         if (!fn)
1290                                 continue;
1291                         if (!try_module_get(fmt->module))
1292                                 continue;
1293                         read_unlock(&binfmt_lock);
1294                         retval = fn(bprm, regs);
1295                         /*
1296                          * Restore the depth counter to its starting value
1297                          * in this call, so we don't have to rely on every
1298                          * load_binary function to restore it on return.
1299                          */
1300                         bprm->recursion_depth = depth;
1301                         if (retval >= 0) {
1302                                 if (depth == 0)
1303                                         tracehook_report_exec(fmt, bprm, regs);
1304                                 put_binfmt(fmt);
1305                                 allow_write_access(bprm->file);
1306                                 if (bprm->file)
1307                                         fput(bprm->file);
1308                                 bprm->file = NULL;
1309                                 current->did_exec = 1;
1310                                 proc_exec_connector(current);
1311                                 return retval;
1312                         }
1313                         read_lock(&binfmt_lock);
1314                         put_binfmt(fmt);
1315                         if (retval != -ENOEXEC || bprm->mm == NULL)
1316                                 break;
1317                         if (!bprm->file) {
1318                                 read_unlock(&binfmt_lock);
1319                                 return retval;
1320                         }
1321                 }
1322                 read_unlock(&binfmt_lock);
1323                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1324                         break;
1325 #ifdef CONFIG_MODULES
1326                 } else {
1327 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1328                         if (printable(bprm->buf[0]) &&
1329                             printable(bprm->buf[1]) &&
1330                             printable(bprm->buf[2]) &&
1331                             printable(bprm->buf[3]))
1332                                 break; /* -ENOEXEC */
1333                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1334 #endif
1335                 }
1336         }
1337         return retval;
1338 }
1339
1340 EXPORT_SYMBOL(search_binary_handler);
1341
1342 /*
1343  * sys_execve() executes a new program.
1344  */
1345 int do_execve(const char * filename,
1346         const char __user *const __user *argv,
1347         const char __user *const __user *envp,
1348         struct pt_regs * regs)
1349 {
1350         struct linux_binprm *bprm;
1351         struct file *file;
1352         struct files_struct *displaced;
1353         bool clear_in_exec;
1354         int retval;
1355
1356         retval = unshare_files(&displaced);
1357         if (retval)
1358                 goto out_ret;
1359
1360         retval = -ENOMEM;
1361         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1362         if (!bprm)
1363                 goto out_files;
1364
1365         retval = prepare_bprm_creds(bprm);
1366         if (retval)
1367                 goto out_free;
1368
1369         retval = check_unsafe_exec(bprm);
1370         if (retval < 0)
1371                 goto out_free;
1372         clear_in_exec = retval;
1373         current->in_execve = 1;
1374
1375         file = open_exec(filename);
1376         retval = PTR_ERR(file);
1377         if (IS_ERR(file))
1378                 goto out_unmark;
1379
1380         sched_exec();
1381
1382         bprm->file = file;
1383         bprm->filename = filename;
1384         bprm->interp = filename;
1385
1386         retval = bprm_mm_init(bprm);
1387         if (retval)
1388                 goto out_file;
1389
1390         bprm->argc = count(argv, MAX_ARG_STRINGS);
1391         if ((retval = bprm->argc) < 0)
1392                 goto out;
1393
1394         bprm->envc = count(envp, MAX_ARG_STRINGS);
1395         if ((retval = bprm->envc) < 0)
1396                 goto out;
1397
1398         retval = prepare_binprm(bprm);
1399         if (retval < 0)
1400                 goto out;
1401
1402         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1403         if (retval < 0)
1404                 goto out;
1405
1406         bprm->exec = bprm->p;
1407         retval = copy_strings(bprm->envc, envp, bprm);
1408         if (retval < 0)
1409                 goto out;
1410
1411         retval = copy_strings(bprm->argc, argv, bprm);
1412         if (retval < 0)
1413                 goto out;
1414
1415         current->flags &= ~PF_KTHREAD;
1416         retval = search_binary_handler(bprm,regs);
1417         if (retval < 0)
1418                 goto out;
1419
1420         /* execve succeeded */
1421         current->fs->in_exec = 0;
1422         current->in_execve = 0;
1423         acct_update_integrals(current);
1424         free_bprm(bprm);
1425         if (displaced)
1426                 put_files_struct(displaced);
1427         return retval;
1428
1429 out:
1430         if (bprm->mm)
1431                 mmput (bprm->mm);
1432
1433 out_file:
1434         if (bprm->file) {
1435                 allow_write_access(bprm->file);
1436                 fput(bprm->file);
1437         }
1438
1439 out_unmark:
1440         if (clear_in_exec)
1441                 current->fs->in_exec = 0;
1442         current->in_execve = 0;
1443
1444 out_free:
1445         free_bprm(bprm);
1446
1447 out_files:
1448         if (displaced)
1449                 reset_files_struct(displaced);
1450 out_ret:
1451         return retval;
1452 }
1453
1454 void set_binfmt(struct linux_binfmt *new)
1455 {
1456         struct mm_struct *mm = current->mm;
1457
1458         if (mm->binfmt)
1459                 module_put(mm->binfmt->module);
1460
1461         mm->binfmt = new;
1462         if (new)
1463                 __module_get(new->module);
1464 }
1465
1466 EXPORT_SYMBOL(set_binfmt);
1467
1468 static int expand_corename(struct core_name *cn)
1469 {
1470         char *old_corename = cn->corename;
1471
1472         cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1473         cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1474
1475         if (!cn->corename) {
1476                 kfree(old_corename);
1477                 return -ENOMEM;
1478         }
1479
1480         return 0;
1481 }
1482
1483 static int cn_printf(struct core_name *cn, const char *fmt, ...)
1484 {
1485         char *cur;
1486         int need;
1487         int ret;
1488         va_list arg;
1489
1490         va_start(arg, fmt);
1491         need = vsnprintf(NULL, 0, fmt, arg);
1492         va_end(arg);
1493
1494         if (likely(need < cn->size - cn->used - 1))
1495                 goto out_printf;
1496
1497         ret = expand_corename(cn);
1498         if (ret)
1499                 goto expand_fail;
1500
1501 out_printf:
1502         cur = cn->corename + cn->used;
1503         va_start(arg, fmt);
1504         vsnprintf(cur, need + 1, fmt, arg);
1505         va_end(arg);
1506         cn->used += need;
1507         return 0;
1508
1509 expand_fail:
1510         return ret;
1511 }
1512
1513 /* format_corename will inspect the pattern parameter, and output a
1514  * name into corename, which must have space for at least
1515  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1516  */
1517 static int format_corename(struct core_name *cn, long signr)
1518 {
1519         const struct cred *cred = current_cred();
1520         const char *pat_ptr = core_pattern;
1521         int ispipe = (*pat_ptr == '|');
1522         int pid_in_pattern = 0;
1523         int err = 0;
1524
1525         cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1526         cn->corename = kmalloc(cn->size, GFP_KERNEL);
1527         cn->used = 0;
1528
1529         if (!cn->corename)
1530                 return -ENOMEM;
1531
1532         /* Repeat as long as we have more pattern to process and more output
1533            space */
1534         while (*pat_ptr) {
1535                 if (*pat_ptr != '%') {
1536                         if (*pat_ptr == 0)
1537                                 goto out;
1538                         err = cn_printf(cn, "%c", *pat_ptr++);
1539                 } else {
1540                         switch (*++pat_ptr) {
1541                         /* single % at the end, drop that */
1542                         case 0:
1543                                 goto out;
1544                         /* Double percent, output one percent */
1545                         case '%':
1546                                 err = cn_printf(cn, "%c", '%');
1547                                 break;
1548                         /* pid */
1549                         case 'p':
1550                                 pid_in_pattern = 1;
1551                                 err = cn_printf(cn, "%d",
1552                                               task_tgid_vnr(current));
1553                                 break;
1554                         /* uid */
1555                         case 'u':
1556                                 err = cn_printf(cn, "%d", cred->uid);
1557                                 break;
1558                         /* gid */
1559                         case 'g':
1560                                 err = cn_printf(cn, "%d", cred->gid);
1561                                 break;
1562                         /* signal that caused the coredump */
1563                         case 's':
1564                                 err = cn_printf(cn, "%ld", signr);
1565                                 break;
1566                         /* UNIX time of coredump */
1567                         case 't': {
1568                                 struct timeval tv;
1569                                 do_gettimeofday(&tv);
1570                                 err = cn_printf(cn, "%lu", tv.tv_sec);
1571                                 break;
1572                         }
1573                         /* hostname */
1574                         case 'h':
1575                                 down_read(&uts_sem);
1576                                 err = cn_printf(cn, "%s",
1577                                               utsname()->nodename);
1578                                 up_read(&uts_sem);
1579                                 break;
1580                         /* executable */
1581                         case 'e':
1582                                 err = cn_printf(cn, "%s", current->comm);
1583                                 break;
1584                         /* core limit size */
1585                         case 'c':
1586                                 err = cn_printf(cn, "%lu",
1587                                               rlimit(RLIMIT_CORE));
1588                                 break;
1589                         default:
1590                                 break;
1591                         }
1592                         ++pat_ptr;
1593                 }
1594
1595                 if (err)
1596                         return err;
1597         }
1598
1599         /* Backward compatibility with core_uses_pid:
1600          *
1601          * If core_pattern does not include a %p (as is the default)
1602          * and core_uses_pid is set, then .%pid will be appended to
1603          * the filename. Do not do this for piped commands. */
1604         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1605                 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1606                 if (err)
1607                         return err;
1608         }
1609 out:
1610         return ispipe;
1611 }
1612
1613 static int zap_process(struct task_struct *start, int exit_code)
1614 {
1615         struct task_struct *t;
1616         int nr = 0;
1617
1618         start->signal->flags = SIGNAL_GROUP_EXIT;
1619         start->signal->group_exit_code = exit_code;
1620         start->signal->group_stop_count = 0;
1621
1622         t = start;
1623         do {
1624                 if (t != current && t->mm) {
1625                         sigaddset(&t->pending.signal, SIGKILL);
1626                         signal_wake_up(t, 1);
1627                         nr++;
1628                 }
1629         } while_each_thread(start, t);
1630
1631         return nr;
1632 }
1633
1634 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1635                                 struct core_state *core_state, int exit_code)
1636 {
1637         struct task_struct *g, *p;
1638         unsigned long flags;
1639         int nr = -EAGAIN;
1640
1641         spin_lock_irq(&tsk->sighand->siglock);
1642         if (!signal_group_exit(tsk->signal)) {
1643                 mm->core_state = core_state;
1644                 nr = zap_process(tsk, exit_code);
1645         }
1646         spin_unlock_irq(&tsk->sighand->siglock);
1647         if (unlikely(nr < 0))
1648                 return nr;
1649
1650         if (atomic_read(&mm->mm_users) == nr + 1)
1651                 goto done;
1652         /*
1653          * We should find and kill all tasks which use this mm, and we should
1654          * count them correctly into ->nr_threads. We don't take tasklist
1655          * lock, but this is safe wrt:
1656          *
1657          * fork:
1658          *      None of sub-threads can fork after zap_process(leader). All
1659          *      processes which were created before this point should be
1660          *      visible to zap_threads() because copy_process() adds the new
1661          *      process to the tail of init_task.tasks list, and lock/unlock
1662          *      of ->siglock provides a memory barrier.
1663          *
1664          * do_exit:
1665          *      The caller holds mm->mmap_sem. This means that the task which
1666          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1667          *      its ->mm.
1668          *
1669          * de_thread:
1670          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1671          *      we must see either old or new leader, this does not matter.
1672          *      However, it can change p->sighand, so lock_task_sighand(p)
1673          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1674          *      it can't fail.
1675          *
1676          *      Note also that "g" can be the old leader with ->mm == NULL
1677          *      and already unhashed and thus removed from ->thread_group.
1678          *      This is OK, __unhash_process()->list_del_rcu() does not
1679          *      clear the ->next pointer, we will find the new leader via
1680          *      next_thread().
1681          */
1682         rcu_read_lock();
1683         for_each_process(g) {
1684                 if (g == tsk->group_leader)
1685                         continue;
1686                 if (g->flags & PF_KTHREAD)
1687                         continue;
1688                 p = g;
1689                 do {
1690                         if (p->mm) {
1691                                 if (unlikely(p->mm == mm)) {
1692                                         lock_task_sighand(p, &flags);
1693                                         nr += zap_process(p, exit_code);
1694                                         unlock_task_sighand(p, &flags);
1695                                 }
1696                                 break;
1697                         }
1698                 } while_each_thread(g, p);
1699         }
1700         rcu_read_unlock();
1701 done:
1702         atomic_set(&core_state->nr_threads, nr);
1703         return nr;
1704 }
1705
1706 static int coredump_wait(int exit_code, struct core_state *core_state)
1707 {
1708         struct task_struct *tsk = current;
1709         struct mm_struct *mm = tsk->mm;
1710         struct completion *vfork_done;
1711         int core_waiters = -EBUSY;
1712
1713         init_completion(&core_state->startup);
1714         core_state->dumper.task = tsk;
1715         core_state->dumper.next = NULL;
1716
1717         down_write(&mm->mmap_sem);
1718         if (!mm->core_state)
1719                 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1720         up_write(&mm->mmap_sem);
1721
1722         if (unlikely(core_waiters < 0))
1723                 goto fail;
1724
1725         /*
1726          * Make sure nobody is waiting for us to release the VM,
1727          * otherwise we can deadlock when we wait on each other
1728          */
1729         vfork_done = tsk->vfork_done;
1730         if (vfork_done) {
1731                 tsk->vfork_done = NULL;
1732                 complete(vfork_done);
1733         }
1734
1735         if (core_waiters)
1736                 wait_for_completion(&core_state->startup);
1737 fail:
1738         return core_waiters;
1739 }
1740
1741 static void coredump_finish(struct mm_struct *mm)
1742 {
1743         struct core_thread *curr, *next;
1744         struct task_struct *task;
1745
1746         next = mm->core_state->dumper.next;
1747         while ((curr = next) != NULL) {
1748                 next = curr->next;
1749                 task = curr->task;
1750                 /*
1751                  * see exit_mm(), curr->task must not see
1752                  * ->task == NULL before we read ->next.
1753                  */
1754                 smp_mb();
1755                 curr->task = NULL;
1756                 wake_up_process(task);
1757         }
1758
1759         mm->core_state = NULL;
1760 }
1761
1762 /*
1763  * set_dumpable converts traditional three-value dumpable to two flags and
1764  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1765  * these bits are not changed atomically.  So get_dumpable can observe the
1766  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1767  * return either old dumpable or new one by paying attention to the order of
1768  * modifying the bits.
1769  *
1770  * dumpable |   mm->flags (binary)
1771  * old  new | initial interim  final
1772  * ---------+-----------------------
1773  *  0    1  |   00      01      01
1774  *  0    2  |   00      10(*)   11
1775  *  1    0  |   01      00      00
1776  *  1    2  |   01      11      11
1777  *  2    0  |   11      10(*)   00
1778  *  2    1  |   11      11      01
1779  *
1780  * (*) get_dumpable regards interim value of 10 as 11.
1781  */
1782 void set_dumpable(struct mm_struct *mm, int value)
1783 {
1784         switch (value) {
1785         case 0:
1786                 clear_bit(MMF_DUMPABLE, &mm->flags);
1787                 smp_wmb();
1788                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1789                 break;
1790         case 1:
1791                 set_bit(MMF_DUMPABLE, &mm->flags);
1792                 smp_wmb();
1793                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1794                 break;
1795         case 2:
1796                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1797                 smp_wmb();
1798                 set_bit(MMF_DUMPABLE, &mm->flags);
1799                 break;
1800         }
1801 }
1802
1803 static int __get_dumpable(unsigned long mm_flags)
1804 {
1805         int ret;
1806
1807         ret = mm_flags & MMF_DUMPABLE_MASK;
1808         return (ret >= 2) ? 2 : ret;
1809 }
1810
1811 int get_dumpable(struct mm_struct *mm)
1812 {
1813         return __get_dumpable(mm->flags);
1814 }
1815
1816 static void wait_for_dump_helpers(struct file *file)
1817 {
1818         struct pipe_inode_info *pipe;
1819
1820         pipe = file->f_path.dentry->d_inode->i_pipe;
1821
1822         pipe_lock(pipe);
1823         pipe->readers++;
1824         pipe->writers--;
1825
1826         while ((pipe->readers > 1) && (!signal_pending(current))) {
1827                 wake_up_interruptible_sync(&pipe->wait);
1828                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1829                 pipe_wait(pipe);
1830         }
1831
1832         pipe->readers--;
1833         pipe->writers++;
1834         pipe_unlock(pipe);
1835
1836 }
1837
1838
1839 /*
1840  * uhm_pipe_setup
1841  * helper function to customize the process used
1842  * to collect the core in userspace.  Specifically
1843  * it sets up a pipe and installs it as fd 0 (stdin)
1844  * for the process.  Returns 0 on success, or
1845  * PTR_ERR on failure.
1846  * Note that it also sets the core limit to 1.  This
1847  * is a special value that we use to trap recursive
1848  * core dumps
1849  */
1850 static int umh_pipe_setup(struct subprocess_info *info)
1851 {
1852         struct file *rp, *wp;
1853         struct fdtable *fdt;
1854         struct coredump_params *cp = (struct coredump_params *)info->data;
1855         struct files_struct *cf = current->files;
1856
1857         wp = create_write_pipe(0);
1858         if (IS_ERR(wp))
1859                 return PTR_ERR(wp);
1860
1861         rp = create_read_pipe(wp, 0);
1862         if (IS_ERR(rp)) {
1863                 free_write_pipe(wp);
1864                 return PTR_ERR(rp);
1865         }
1866
1867         cp->file = wp;
1868
1869         sys_close(0);
1870         fd_install(0, rp);
1871         spin_lock(&cf->file_lock);
1872         fdt = files_fdtable(cf);
1873         FD_SET(0, fdt->open_fds);
1874         FD_CLR(0, fdt->close_on_exec);
1875         spin_unlock(&cf->file_lock);
1876
1877         /* and disallow core files too */
1878         current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
1879
1880         return 0;
1881 }
1882
1883 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1884 {
1885         struct core_state core_state;
1886         struct core_name cn;
1887         struct mm_struct *mm = current->mm;
1888         struct linux_binfmt * binfmt;
1889         const struct cred *old_cred;
1890         struct cred *cred;
1891         int retval = 0;
1892         int flag = 0;
1893         int ispipe;
1894         static atomic_t core_dump_count = ATOMIC_INIT(0);
1895         struct coredump_params cprm = {
1896                 .signr = signr,
1897                 .regs = regs,
1898                 .limit = rlimit(RLIMIT_CORE),
1899                 /*
1900                  * We must use the same mm->flags while dumping core to avoid
1901                  * inconsistency of bit flags, since this flag is not protected
1902                  * by any locks.
1903                  */
1904                 .mm_flags = mm->flags,
1905         };
1906
1907         audit_core_dumps(signr);
1908
1909         binfmt = mm->binfmt;
1910         if (!binfmt || !binfmt->core_dump)
1911                 goto fail;
1912         if (!__get_dumpable(cprm.mm_flags))
1913                 goto fail;
1914
1915         cred = prepare_creds();
1916         if (!cred)
1917                 goto fail;
1918         /*
1919          *      We cannot trust fsuid as being the "true" uid of the
1920          *      process nor do we know its entire history. We only know it
1921          *      was tainted so we dump it as root in mode 2.
1922          */
1923         if (__get_dumpable(cprm.mm_flags) == 2) {
1924                 /* Setuid core dump mode */
1925                 flag = O_EXCL;          /* Stop rewrite attacks */
1926                 cred->fsuid = 0;        /* Dump root private */
1927         }
1928
1929         retval = coredump_wait(exit_code, &core_state);
1930         if (retval < 0)
1931                 goto fail_creds;
1932
1933         old_cred = override_creds(cred);
1934
1935         /*
1936          * Clear any false indication of pending signals that might
1937          * be seen by the filesystem code called to write the core file.
1938          */
1939         clear_thread_flag(TIF_SIGPENDING);
1940
1941         ispipe = format_corename(&cn, signr);
1942
1943         if (ispipe == -ENOMEM) {
1944                 printk(KERN_WARNING "format_corename failed\n");
1945                 printk(KERN_WARNING "Aborting core\n");
1946                 goto fail_corename;
1947         }
1948
1949         if (ispipe) {
1950                 int dump_count;
1951                 char **helper_argv;
1952
1953                 if (cprm.limit == 1) {
1954                         /*
1955                          * Normally core limits are irrelevant to pipes, since
1956                          * we're not writing to the file system, but we use
1957                          * cprm.limit of 1 here as a speacial value. Any
1958                          * non-1 limit gets set to RLIM_INFINITY below, but
1959                          * a limit of 0 skips the dump.  This is a consistent
1960                          * way to catch recursive crashes.  We can still crash
1961                          * if the core_pattern binary sets RLIM_CORE =  !1
1962                          * but it runs as root, and can do lots of stupid things
1963                          * Note that we use task_tgid_vnr here to grab the pid
1964                          * of the process group leader.  That way we get the
1965                          * right pid if a thread in a multi-threaded
1966                          * core_pattern process dies.
1967                          */
1968                         printk(KERN_WARNING
1969                                 "Process %d(%s) has RLIMIT_CORE set to 1\n",
1970                                 task_tgid_vnr(current), current->comm);
1971                         printk(KERN_WARNING "Aborting core\n");
1972                         goto fail_unlock;
1973                 }
1974                 cprm.limit = RLIM_INFINITY;
1975
1976                 dump_count = atomic_inc_return(&core_dump_count);
1977                 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
1978                         printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
1979                                task_tgid_vnr(current), current->comm);
1980                         printk(KERN_WARNING "Skipping core dump\n");
1981                         goto fail_dropcount;
1982                 }
1983
1984                 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
1985                 if (!helper_argv) {
1986                         printk(KERN_WARNING "%s failed to allocate memory\n",
1987                                __func__);
1988                         goto fail_dropcount;
1989                 }
1990
1991                 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
1992                                         NULL, UMH_WAIT_EXEC, umh_pipe_setup,
1993                                         NULL, &cprm);
1994                 argv_free(helper_argv);
1995                 if (retval) {
1996                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1997                                cn.corename);
1998                         goto close_fail;
1999                 }
2000         } else {
2001                 struct inode *inode;
2002
2003                 if (cprm.limit < binfmt->min_coredump)
2004                         goto fail_unlock;
2005
2006                 cprm.file = filp_open(cn.corename,
2007                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2008                                  0600);
2009                 if (IS_ERR(cprm.file))
2010                         goto fail_unlock;
2011
2012                 inode = cprm.file->f_path.dentry->d_inode;
2013                 if (inode->i_nlink > 1)
2014                         goto close_fail;
2015                 if (d_unhashed(cprm.file->f_path.dentry))
2016                         goto close_fail;
2017                 /*
2018                  * AK: actually i see no reason to not allow this for named
2019                  * pipes etc, but keep the previous behaviour for now.
2020                  */
2021                 if (!S_ISREG(inode->i_mode))
2022                         goto close_fail;
2023                 /*
2024                  * Dont allow local users get cute and trick others to coredump
2025                  * into their pre-created files.
2026                  */
2027                 if (inode->i_uid != current_fsuid())
2028                         goto close_fail;
2029                 if (!cprm.file->f_op || !cprm.file->f_op->write)
2030                         goto close_fail;
2031                 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2032                         goto close_fail;
2033         }
2034
2035         retval = binfmt->core_dump(&cprm);
2036         if (retval)
2037                 current->signal->group_exit_code |= 0x80;
2038
2039         if (ispipe && core_pipe_limit)
2040                 wait_for_dump_helpers(cprm.file);
2041 close_fail:
2042         if (cprm.file)
2043                 filp_close(cprm.file, NULL);
2044 fail_dropcount:
2045         if (ispipe)
2046                 atomic_dec(&core_dump_count);
2047 fail_unlock:
2048         kfree(cn.corename);
2049 fail_corename:
2050         coredump_finish(mm);
2051         revert_creds(old_cred);
2052 fail_creds:
2053         put_cred(cred);
2054 fail:
2055         return;
2056 }
2057
2058 /*
2059  * Core dumping helper functions.  These are the only things you should
2060  * do on a core-file: use only these functions to write out all the
2061  * necessary info.
2062  */
2063 int dump_write(struct file *file, const void *addr, int nr)
2064 {
2065         return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2066 }
2067 EXPORT_SYMBOL(dump_write);
2068
2069 int dump_seek(struct file *file, loff_t off)
2070 {
2071         int ret = 1;
2072
2073         if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2074                 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2075                         return 0;
2076         } else {
2077                 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2078
2079                 if (!buf)
2080                         return 0;
2081                 while (off > 0) {
2082                         unsigned long n = off;
2083
2084                         if (n > PAGE_SIZE)
2085                                 n = PAGE_SIZE;
2086                         if (!dump_write(file, buf, n)) {
2087                                 ret = 0;
2088                                 break;
2089                         }
2090                         off -= n;
2091                 }
2092                 free_page((unsigned long)buf);
2093         }
2094         return ret;
2095 }
2096 EXPORT_SYMBOL(dump_seek);