Merge branch 'master' into next
[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/smp_lock.h>
32 #include <linux/swap.h>
33 #include <linux/string.h>
34 #include <linux/init.h>
35 #include <linux/pagemap.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/ima.h>
49 #include <linux/syscalls.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 #include <linux/tracehook.h>
54 #include <linux/kmod.h>
55 #include <linux/fsnotify.h>
56
57 #include <asm/uaccess.h>
58 #include <asm/mmu_context.h>
59 #include <asm/tlb.h>
60 #include "internal.h"
61
62 int core_uses_pid;
63 char core_pattern[CORENAME_MAX_SIZE] = "core";
64 int suid_dumpable = 0;
65
66 /* The maximal length of core_pattern is also specified in sysctl.c */
67
68 static LIST_HEAD(formats);
69 static DEFINE_RWLOCK(binfmt_lock);
70
71 int register_binfmt(struct linux_binfmt * fmt)
72 {
73         if (!fmt)
74                 return -EINVAL;
75         write_lock(&binfmt_lock);
76         list_add(&fmt->lh, &formats);
77         write_unlock(&binfmt_lock);
78         return 0;       
79 }
80
81 EXPORT_SYMBOL(register_binfmt);
82
83 void unregister_binfmt(struct linux_binfmt * fmt)
84 {
85         write_lock(&binfmt_lock);
86         list_del(&fmt->lh);
87         write_unlock(&binfmt_lock);
88 }
89
90 EXPORT_SYMBOL(unregister_binfmt);
91
92 static inline void put_binfmt(struct linux_binfmt * fmt)
93 {
94         module_put(fmt->module);
95 }
96
97 /*
98  * Note that a shared library must be both readable and executable due to
99  * security reasons.
100  *
101  * Also note that we take the address to load from from the file itself.
102  */
103 SYSCALL_DEFINE1(uselib, const char __user *, library)
104 {
105         struct file *file;
106         struct nameidata nd;
107         char *tmp = getname(library);
108         int error = PTR_ERR(tmp);
109
110         if (!IS_ERR(tmp)) {
111                 error = path_lookup_open(AT_FDCWD, tmp,
112                                          LOOKUP_FOLLOW, &nd,
113                                          FMODE_READ|FMODE_EXEC);
114                 putname(tmp);
115         }
116         if (error)
117                 goto out;
118
119         error = -EINVAL;
120         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
121                 goto exit;
122
123         error = -EACCES;
124         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
125                 goto exit;
126
127         error = inode_permission(nd.path.dentry->d_inode,
128                                  MAY_READ | MAY_EXEC | MAY_OPEN);
129         if (error)
130                 goto exit;
131         error = ima_path_check(&nd.path, MAY_READ | MAY_EXEC | MAY_OPEN);
132         if (error)
133                 goto exit;
134
135         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
136         error = PTR_ERR(file);
137         if (IS_ERR(file))
138                 goto out;
139
140         fsnotify_open(file->f_path.dentry);
141
142         error = -ENOEXEC;
143         if(file->f_op) {
144                 struct linux_binfmt * fmt;
145
146                 read_lock(&binfmt_lock);
147                 list_for_each_entry(fmt, &formats, lh) {
148                         if (!fmt->load_shlib)
149                                 continue;
150                         if (!try_module_get(fmt->module))
151                                 continue;
152                         read_unlock(&binfmt_lock);
153                         error = fmt->load_shlib(file);
154                         read_lock(&binfmt_lock);
155                         put_binfmt(fmt);
156                         if (error != -ENOEXEC)
157                                 break;
158                 }
159                 read_unlock(&binfmt_lock);
160         }
161         fput(file);
162 out:
163         return error;
164 exit:
165         release_open_intent(&nd);
166         path_put(&nd.path);
167         goto out;
168 }
169
170 #ifdef CONFIG_MMU
171
172 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
173                 int write)
174 {
175         struct page *page;
176         int ret;
177
178 #ifdef CONFIG_STACK_GROWSUP
179         if (write) {
180                 ret = expand_stack_downwards(bprm->vma, pos);
181                 if (ret < 0)
182                         return NULL;
183         }
184 #endif
185         ret = get_user_pages(current, bprm->mm, pos,
186                         1, write, 1, &page, NULL);
187         if (ret <= 0)
188                 return NULL;
189
190         if (write) {
191                 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
192                 struct rlimit *rlim;
193
194                 /*
195                  * We've historically supported up to 32 pages (ARG_MAX)
196                  * of argument strings even with small stacks
197                  */
198                 if (size <= ARG_MAX)
199                         return page;
200
201                 /*
202                  * Limit to 1/4-th the stack size for the argv+env strings.
203                  * This ensures that:
204                  *  - the remaining binfmt code will not run out of stack space,
205                  *  - the program will have a reasonable amount of stack left
206                  *    to work from.
207                  */
208                 rlim = current->signal->rlim;
209                 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
210                         put_page(page);
211                         return NULL;
212                 }
213         }
214
215         return page;
216 }
217
218 static void put_arg_page(struct page *page)
219 {
220         put_page(page);
221 }
222
223 static void free_arg_page(struct linux_binprm *bprm, int i)
224 {
225 }
226
227 static void free_arg_pages(struct linux_binprm *bprm)
228 {
229 }
230
231 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
232                 struct page *page)
233 {
234         flush_cache_page(bprm->vma, pos, page_to_pfn(page));
235 }
236
237 static int __bprm_mm_init(struct linux_binprm *bprm)
238 {
239         int err;
240         struct vm_area_struct *vma = NULL;
241         struct mm_struct *mm = bprm->mm;
242
243         bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
244         if (!vma)
245                 return -ENOMEM;
246
247         down_write(&mm->mmap_sem);
248         vma->vm_mm = mm;
249
250         /*
251          * Place the stack at the largest stack address the architecture
252          * supports. Later, we'll move this to an appropriate place. We don't
253          * use STACK_TOP because that can depend on attributes which aren't
254          * configured yet.
255          */
256         vma->vm_end = STACK_TOP_MAX;
257         vma->vm_start = vma->vm_end - PAGE_SIZE;
258         vma->vm_flags = VM_STACK_FLAGS;
259         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
260         err = insert_vm_struct(mm, vma);
261         if (err)
262                 goto err;
263
264         mm->stack_vm = mm->total_vm = 1;
265         up_write(&mm->mmap_sem);
266         bprm->p = vma->vm_end - sizeof(void *);
267         return 0;
268 err:
269         up_write(&mm->mmap_sem);
270         bprm->vma = NULL;
271         kmem_cache_free(vm_area_cachep, vma);
272         return err;
273 }
274
275 static bool valid_arg_len(struct linux_binprm *bprm, long len)
276 {
277         return len <= MAX_ARG_STRLEN;
278 }
279
280 #else
281
282 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
283                 int write)
284 {
285         struct page *page;
286
287         page = bprm->page[pos / PAGE_SIZE];
288         if (!page && write) {
289                 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
290                 if (!page)
291                         return NULL;
292                 bprm->page[pos / PAGE_SIZE] = page;
293         }
294
295         return page;
296 }
297
298 static void put_arg_page(struct page *page)
299 {
300 }
301
302 static void free_arg_page(struct linux_binprm *bprm, int i)
303 {
304         if (bprm->page[i]) {
305                 __free_page(bprm->page[i]);
306                 bprm->page[i] = NULL;
307         }
308 }
309
310 static void free_arg_pages(struct linux_binprm *bprm)
311 {
312         int i;
313
314         for (i = 0; i < MAX_ARG_PAGES; i++)
315                 free_arg_page(bprm, i);
316 }
317
318 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
319                 struct page *page)
320 {
321 }
322
323 static int __bprm_mm_init(struct linux_binprm *bprm)
324 {
325         bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
326         return 0;
327 }
328
329 static bool valid_arg_len(struct linux_binprm *bprm, long len)
330 {
331         return len <= bprm->p;
332 }
333
334 #endif /* CONFIG_MMU */
335
336 /*
337  * Create a new mm_struct and populate it with a temporary stack
338  * vm_area_struct.  We don't have enough context at this point to set the stack
339  * flags, permissions, and offset, so we use temporary values.  We'll update
340  * them later in setup_arg_pages().
341  */
342 int bprm_mm_init(struct linux_binprm *bprm)
343 {
344         int err;
345         struct mm_struct *mm = NULL;
346
347         bprm->mm = mm = mm_alloc();
348         err = -ENOMEM;
349         if (!mm)
350                 goto err;
351
352         err = init_new_context(current, mm);
353         if (err)
354                 goto err;
355
356         err = __bprm_mm_init(bprm);
357         if (err)
358                 goto err;
359
360         return 0;
361
362 err:
363         if (mm) {
364                 bprm->mm = NULL;
365                 mmdrop(mm);
366         }
367
368         return err;
369 }
370
371 /*
372  * count() counts the number of strings in array ARGV.
373  */
374 static int count(char __user * __user * argv, int max)
375 {
376         int i = 0;
377
378         if (argv != NULL) {
379                 for (;;) {
380                         char __user * p;
381
382                         if (get_user(p, argv))
383                                 return -EFAULT;
384                         if (!p)
385                                 break;
386                         argv++;
387                         if (i++ >= max)
388                                 return -E2BIG;
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, char __user * __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                 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                         offset = pos % PAGE_SIZE;
433                         if (offset == 0)
434                                 offset = PAGE_SIZE;
435
436                         bytes_to_copy = offset;
437                         if (bytes_to_copy > len)
438                                 bytes_to_copy = len;
439
440                         offset -= bytes_to_copy;
441                         pos -= bytes_to_copy;
442                         str -= bytes_to_copy;
443                         len -= bytes_to_copy;
444
445                         if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
446                                 struct page *page;
447
448                                 page = get_arg_page(bprm, pos, 1);
449                                 if (!page) {
450                                         ret = -E2BIG;
451                                         goto out;
452                                 }
453
454                                 if (kmapped_page) {
455                                         flush_kernel_dcache_page(kmapped_page);
456                                         kunmap(kmapped_page);
457                                         put_arg_page(kmapped_page);
458                                 }
459                                 kmapped_page = page;
460                                 kaddr = kmap(kmapped_page);
461                                 kpos = pos & PAGE_MASK;
462                                 flush_arg_page(bprm, kpos, kmapped_page);
463                         }
464                         if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
465                                 ret = -EFAULT;
466                                 goto out;
467                         }
468                 }
469         }
470         ret = 0;
471 out:
472         if (kmapped_page) {
473                 flush_kernel_dcache_page(kmapped_page);
474                 kunmap(kmapped_page);
475                 put_arg_page(kmapped_page);
476         }
477         return ret;
478 }
479
480 /*
481  * Like copy_strings, but get argv and its values from kernel memory.
482  */
483 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
484 {
485         int r;
486         mm_segment_t oldfs = get_fs();
487         set_fs(KERNEL_DS);
488         r = copy_strings(argc, (char __user * __user *)argv, bprm);
489         set_fs(oldfs);
490         return r;
491 }
492 EXPORT_SYMBOL(copy_strings_kernel);
493
494 #ifdef CONFIG_MMU
495
496 /*
497  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
498  * the binfmt code determines where the new stack should reside, we shift it to
499  * its final location.  The process proceeds as follows:
500  *
501  * 1) Use shift to calculate the new vma endpoints.
502  * 2) Extend vma to cover both the old and new ranges.  This ensures the
503  *    arguments passed to subsequent functions are consistent.
504  * 3) Move vma's page tables to the new range.
505  * 4) Free up any cleared pgd range.
506  * 5) Shrink the vma to cover only the new range.
507  */
508 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
509 {
510         struct mm_struct *mm = vma->vm_mm;
511         unsigned long old_start = vma->vm_start;
512         unsigned long old_end = vma->vm_end;
513         unsigned long length = old_end - old_start;
514         unsigned long new_start = old_start - shift;
515         unsigned long new_end = old_end - shift;
516         struct mmu_gather *tlb;
517
518         BUG_ON(new_start > new_end);
519
520         /*
521          * ensure there are no vmas between where we want to go
522          * and where we are
523          */
524         if (vma != find_vma(mm, new_start))
525                 return -EFAULT;
526
527         /*
528          * cover the whole range: [new_start, old_end)
529          */
530         vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
531
532         /*
533          * move the page tables downwards, on failure we rely on
534          * process cleanup to remove whatever mess we made.
535          */
536         if (length != move_page_tables(vma, old_start,
537                                        vma, new_start, length))
538                 return -ENOMEM;
539
540         lru_add_drain();
541         tlb = tlb_gather_mmu(mm, 0);
542         if (new_end > old_start) {
543                 /*
544                  * when the old and new regions overlap clear from new_end.
545                  */
546                 free_pgd_range(tlb, new_end, old_end, new_end,
547                         vma->vm_next ? vma->vm_next->vm_start : 0);
548         } else {
549                 /*
550                  * otherwise, clean from old_start; this is done to not touch
551                  * the address space in [new_end, old_start) some architectures
552                  * have constraints on va-space that make this illegal (IA64) -
553                  * for the others its just a little faster.
554                  */
555                 free_pgd_range(tlb, old_start, old_end, new_end,
556                         vma->vm_next ? vma->vm_next->vm_start : 0);
557         }
558         tlb_finish_mmu(tlb, new_end, old_end);
559
560         /*
561          * shrink the vma to just the new range.
562          */
563         vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
564
565         return 0;
566 }
567
568 #define EXTRA_STACK_VM_PAGES    20      /* random */
569
570 /*
571  * Finalizes the stack vm_area_struct. The flags and permissions are updated,
572  * the stack is optionally relocated, and some extra space is added.
573  */
574 int setup_arg_pages(struct linux_binprm *bprm,
575                     unsigned long stack_top,
576                     int executable_stack)
577 {
578         unsigned long ret;
579         unsigned long stack_shift;
580         struct mm_struct *mm = current->mm;
581         struct vm_area_struct *vma = bprm->vma;
582         struct vm_area_struct *prev = NULL;
583         unsigned long vm_flags;
584         unsigned long stack_base;
585
586 #ifdef CONFIG_STACK_GROWSUP
587         /* Limit stack size to 1GB */
588         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
589         if (stack_base > (1 << 30))
590                 stack_base = 1 << 30;
591
592         /* Make sure we didn't let the argument array grow too large. */
593         if (vma->vm_end - vma->vm_start > stack_base)
594                 return -ENOMEM;
595
596         stack_base = PAGE_ALIGN(stack_top - stack_base);
597
598         stack_shift = vma->vm_start - stack_base;
599         mm->arg_start = bprm->p - stack_shift;
600         bprm->p = vma->vm_end - stack_shift;
601 #else
602         stack_top = arch_align_stack(stack_top);
603         stack_top = PAGE_ALIGN(stack_top);
604         stack_shift = vma->vm_end - stack_top;
605
606         bprm->p -= stack_shift;
607         mm->arg_start = bprm->p;
608 #endif
609
610         if (bprm->loader)
611                 bprm->loader -= stack_shift;
612         bprm->exec -= stack_shift;
613
614         down_write(&mm->mmap_sem);
615         vm_flags = VM_STACK_FLAGS;
616
617         /*
618          * Adjust stack execute permissions; explicitly enable for
619          * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
620          * (arch default) otherwise.
621          */
622         if (unlikely(executable_stack == EXSTACK_ENABLE_X))
623                 vm_flags |= VM_EXEC;
624         else if (executable_stack == EXSTACK_DISABLE_X)
625                 vm_flags &= ~VM_EXEC;
626         vm_flags |= mm->def_flags;
627
628         ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
629                         vm_flags);
630         if (ret)
631                 goto out_unlock;
632         BUG_ON(prev != vma);
633
634         /* Move stack pages down in memory. */
635         if (stack_shift) {
636                 ret = shift_arg_pages(vma, stack_shift);
637                 if (ret) {
638                         up_write(&mm->mmap_sem);
639                         return ret;
640                 }
641         }
642
643 #ifdef CONFIG_STACK_GROWSUP
644         stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
645 #else
646         stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
647 #endif
648         ret = expand_stack(vma, stack_base);
649         if (ret)
650                 ret = -EFAULT;
651
652 out_unlock:
653         up_write(&mm->mmap_sem);
654         return 0;
655 }
656 EXPORT_SYMBOL(setup_arg_pages);
657
658 #endif /* CONFIG_MMU */
659
660 struct file *open_exec(const char *name)
661 {
662         struct nameidata nd;
663         struct file *file;
664         int err;
665
666         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
667                                 FMODE_READ|FMODE_EXEC);
668         if (err)
669                 goto out;
670
671         err = -EACCES;
672         if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
673                 goto out_path_put;
674
675         if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
676                 goto out_path_put;
677
678         err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
679         if (err)
680                 goto out_path_put;
681         err = ima_path_check(&nd.path, MAY_EXEC | MAY_OPEN);
682         if (err)
683                 goto out_path_put;
684
685         file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
686         if (IS_ERR(file))
687                 return file;
688
689         fsnotify_open(file->f_path.dentry);
690
691         err = deny_write_access(file);
692         if (err) {
693                 fput(file);
694                 goto out;
695         }
696
697         return file;
698
699  out_path_put:
700         release_open_intent(&nd);
701         path_put(&nd.path);
702  out:
703         return ERR_PTR(err);
704 }
705 EXPORT_SYMBOL(open_exec);
706
707 int kernel_read(struct file *file, unsigned long offset,
708         char *addr, unsigned long count)
709 {
710         mm_segment_t old_fs;
711         loff_t pos = offset;
712         int result;
713
714         old_fs = get_fs();
715         set_fs(get_ds());
716         /* The cast to a user pointer is valid due to the set_fs() */
717         result = vfs_read(file, (void __user *)addr, count, &pos);
718         set_fs(old_fs);
719         return result;
720 }
721
722 EXPORT_SYMBOL(kernel_read);
723
724 static int exec_mmap(struct mm_struct *mm)
725 {
726         struct task_struct *tsk;
727         struct mm_struct * old_mm, *active_mm;
728
729         /* Notify parent that we're no longer interested in the old VM */
730         tsk = current;
731         old_mm = current->mm;
732         mm_release(tsk, old_mm);
733
734         if (old_mm) {
735                 /*
736                  * Make sure that if there is a core dump in progress
737                  * for the old mm, we get out and die instead of going
738                  * through with the exec.  We must hold mmap_sem around
739                  * checking core_state and changing tsk->mm.
740                  */
741                 down_read(&old_mm->mmap_sem);
742                 if (unlikely(old_mm->core_state)) {
743                         up_read(&old_mm->mmap_sem);
744                         return -EINTR;
745                 }
746         }
747         task_lock(tsk);
748         active_mm = tsk->active_mm;
749         tsk->mm = mm;
750         tsk->active_mm = mm;
751         activate_mm(active_mm, mm);
752         task_unlock(tsk);
753         arch_pick_mmap_layout(mm);
754         if (old_mm) {
755                 up_read(&old_mm->mmap_sem);
756                 BUG_ON(active_mm != old_mm);
757                 mm_update_next_owner(old_mm);
758                 mmput(old_mm);
759                 return 0;
760         }
761         mmdrop(active_mm);
762         return 0;
763 }
764
765 /*
766  * This function makes sure the current process has its own signal table,
767  * so that flush_signal_handlers can later reset the handlers without
768  * disturbing other processes.  (Other processes might share the signal
769  * table via the CLONE_SIGHAND option to clone().)
770  */
771 static int de_thread(struct task_struct *tsk)
772 {
773         struct signal_struct *sig = tsk->signal;
774         struct sighand_struct *oldsighand = tsk->sighand;
775         spinlock_t *lock = &oldsighand->siglock;
776         int count;
777
778         if (thread_group_empty(tsk))
779                 goto no_thread_group;
780
781         /*
782          * Kill all other threads in the thread group.
783          */
784         spin_lock_irq(lock);
785         if (signal_group_exit(sig)) {
786                 /*
787                  * Another group action in progress, just
788                  * return so that the signal is processed.
789                  */
790                 spin_unlock_irq(lock);
791                 return -EAGAIN;
792         }
793         sig->group_exit_task = tsk;
794         zap_other_threads(tsk);
795
796         /* Account for the thread group leader hanging around: */
797         count = thread_group_leader(tsk) ? 1 : 2;
798         sig->notify_count = count;
799         while (atomic_read(&sig->count) > count) {
800                 __set_current_state(TASK_UNINTERRUPTIBLE);
801                 spin_unlock_irq(lock);
802                 schedule();
803                 spin_lock_irq(lock);
804         }
805         spin_unlock_irq(lock);
806
807         /*
808          * At this point all other threads have exited, all we have to
809          * do is to wait for the thread group leader to become inactive,
810          * and to assume its PID:
811          */
812         if (!thread_group_leader(tsk)) {
813                 struct task_struct *leader = tsk->group_leader;
814
815                 sig->notify_count = -1; /* for exit_notify() */
816                 for (;;) {
817                         write_lock_irq(&tasklist_lock);
818                         if (likely(leader->exit_state))
819                                 break;
820                         __set_current_state(TASK_UNINTERRUPTIBLE);
821                         write_unlock_irq(&tasklist_lock);
822                         schedule();
823                 }
824
825                 /*
826                  * The only record we have of the real-time age of a
827                  * process, regardless of execs it's done, is start_time.
828                  * All the past CPU time is accumulated in signal_struct
829                  * from sister threads now dead.  But in this non-leader
830                  * exec, nothing survives from the original leader thread,
831                  * whose birth marks the true age of this process now.
832                  * When we take on its identity by switching to its PID, we
833                  * also take its birthdate (always earlier than our own).
834                  */
835                 tsk->start_time = leader->start_time;
836
837                 BUG_ON(!same_thread_group(leader, tsk));
838                 BUG_ON(has_group_leader_pid(tsk));
839                 /*
840                  * An exec() starts a new thread group with the
841                  * TGID of the previous thread group. Rehash the
842                  * two threads with a switched PID, and release
843                  * the former thread group leader:
844                  */
845
846                 /* Become a process group leader with the old leader's pid.
847                  * The old leader becomes a thread of the this thread group.
848                  * Note: The old leader also uses this pid until release_task
849                  *       is called.  Odd but simple and correct.
850                  */
851                 detach_pid(tsk, PIDTYPE_PID);
852                 tsk->pid = leader->pid;
853                 attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
854                 transfer_pid(leader, tsk, PIDTYPE_PGID);
855                 transfer_pid(leader, tsk, PIDTYPE_SID);
856                 list_replace_rcu(&leader->tasks, &tsk->tasks);
857
858                 tsk->group_leader = tsk;
859                 leader->group_leader = tsk;
860
861                 tsk->exit_signal = SIGCHLD;
862
863                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
864                 leader->exit_state = EXIT_DEAD;
865                 write_unlock_irq(&tasklist_lock);
866
867                 release_task(leader);
868         }
869
870         sig->group_exit_task = NULL;
871         sig->notify_count = 0;
872
873 no_thread_group:
874         exit_itimers(sig);
875         flush_itimer_signals();
876
877         if (atomic_read(&oldsighand->count) != 1) {
878                 struct sighand_struct *newsighand;
879                 /*
880                  * This ->sighand is shared with the CLONE_SIGHAND
881                  * but not CLONE_THREAD task, switch to the new one.
882                  */
883                 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
884                 if (!newsighand)
885                         return -ENOMEM;
886
887                 atomic_set(&newsighand->count, 1);
888                 memcpy(newsighand->action, oldsighand->action,
889                        sizeof(newsighand->action));
890
891                 write_lock_irq(&tasklist_lock);
892                 spin_lock(&oldsighand->siglock);
893                 rcu_assign_pointer(tsk->sighand, newsighand);
894                 spin_unlock(&oldsighand->siglock);
895                 write_unlock_irq(&tasklist_lock);
896
897                 __cleanup_sighand(oldsighand);
898         }
899
900         BUG_ON(!thread_group_leader(tsk));
901         return 0;
902 }
903
904 /*
905  * These functions flushes out all traces of the currently running executable
906  * so that a new one can be started
907  */
908 static void flush_old_files(struct files_struct * files)
909 {
910         long j = -1;
911         struct fdtable *fdt;
912
913         spin_lock(&files->file_lock);
914         for (;;) {
915                 unsigned long set, i;
916
917                 j++;
918                 i = j * __NFDBITS;
919                 fdt = files_fdtable(files);
920                 if (i >= fdt->max_fds)
921                         break;
922                 set = fdt->close_on_exec->fds_bits[j];
923                 if (!set)
924                         continue;
925                 fdt->close_on_exec->fds_bits[j] = 0;
926                 spin_unlock(&files->file_lock);
927                 for ( ; set ; i++,set >>= 1) {
928                         if (set & 1) {
929                                 sys_close(i);
930                         }
931                 }
932                 spin_lock(&files->file_lock);
933
934         }
935         spin_unlock(&files->file_lock);
936 }
937
938 char *get_task_comm(char *buf, struct task_struct *tsk)
939 {
940         /* buf must be at least sizeof(tsk->comm) in size */
941         task_lock(tsk);
942         strncpy(buf, tsk->comm, sizeof(tsk->comm));
943         task_unlock(tsk);
944         return buf;
945 }
946
947 void set_task_comm(struct task_struct *tsk, char *buf)
948 {
949         task_lock(tsk);
950         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
951         task_unlock(tsk);
952 }
953
954 int flush_old_exec(struct linux_binprm * bprm)
955 {
956         char * name;
957         int i, ch, retval;
958         char tcomm[sizeof(current->comm)];
959
960         /*
961          * Make sure we have a private signal table and that
962          * we are unassociated from the previous thread group.
963          */
964         retval = de_thread(current);
965         if (retval)
966                 goto out;
967
968         set_mm_exe_file(bprm->mm, bprm->file);
969
970         /*
971          * Release all of the old mmap stuff
972          */
973         retval = exec_mmap(bprm->mm);
974         if (retval)
975                 goto out;
976
977         bprm->mm = NULL;                /* We're using it now */
978
979         /* This is the point of no return */
980         current->sas_ss_sp = current->sas_ss_size = 0;
981
982         if (current_euid() == current_uid() && current_egid() == current_gid())
983                 set_dumpable(current->mm, 1);
984         else
985                 set_dumpable(current->mm, suid_dumpable);
986
987         name = bprm->filename;
988
989         /* Copies the binary name from after last slash */
990         for (i=0; (ch = *(name++)) != '\0';) {
991                 if (ch == '/')
992                         i = 0; /* overwrite what we wrote */
993                 else
994                         if (i < (sizeof(tcomm) - 1))
995                                 tcomm[i++] = ch;
996         }
997         tcomm[i] = '\0';
998         set_task_comm(current, tcomm);
999
1000         current->flags &= ~PF_RANDOMIZE;
1001         flush_thread();
1002
1003         /* Set the new mm task size. We have to do that late because it may
1004          * depend on TIF_32BIT which is only updated in flush_thread() on
1005          * some architectures like powerpc
1006          */
1007         current->mm->task_size = TASK_SIZE;
1008
1009         /* install the new credentials */
1010         if (bprm->cred->uid != current_euid() ||
1011             bprm->cred->gid != current_egid()) {
1012                 current->pdeath_signal = 0;
1013         } else if (file_permission(bprm->file, MAY_READ) ||
1014                    bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1015                 set_dumpable(current->mm, suid_dumpable);
1016         }
1017
1018         current->personality &= ~bprm->per_clear;
1019
1020         /* An exec changes our domain. We are no longer part of the thread
1021            group */
1022
1023         current->self_exec_id++;
1024                         
1025         flush_signal_handlers(current, 0);
1026         flush_old_files(current->files);
1027
1028         return 0;
1029
1030 out:
1031         return retval;
1032 }
1033
1034 EXPORT_SYMBOL(flush_old_exec);
1035
1036 /*
1037  * install the new credentials for this executable
1038  */
1039 void install_exec_creds(struct linux_binprm *bprm)
1040 {
1041         security_bprm_committing_creds(bprm);
1042
1043         commit_creds(bprm->cred);
1044         bprm->cred = NULL;
1045
1046         /* cred_exec_mutex must be held at least to this point to prevent
1047          * ptrace_attach() from altering our determination of the task's
1048          * credentials; any time after this it may be unlocked */
1049
1050         security_bprm_committed_creds(bprm);
1051 }
1052 EXPORT_SYMBOL(install_exec_creds);
1053
1054 /*
1055  * determine how safe it is to execute the proposed program
1056  * - the caller must hold current->cred_exec_mutex to protect against
1057  *   PTRACE_ATTACH
1058  */
1059 void check_unsafe_exec(struct linux_binprm *bprm)
1060 {
1061         struct task_struct *p = current;
1062
1063         bprm->unsafe = tracehook_unsafe_exec(p);
1064
1065         if (atomic_read(&p->fs->count) > 1 ||
1066             atomic_read(&p->files->count) > 1 ||
1067             atomic_read(&p->sighand->count) > 1)
1068                 bprm->unsafe |= LSM_UNSAFE_SHARE;
1069 }
1070
1071 /* 
1072  * Fill the binprm structure from the inode. 
1073  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1074  *
1075  * This may be called multiple times for binary chains (scripts for example).
1076  */
1077 int prepare_binprm(struct linux_binprm *bprm)
1078 {
1079         umode_t mode;
1080         struct inode * inode = bprm->file->f_path.dentry->d_inode;
1081         int retval;
1082
1083         mode = inode->i_mode;
1084         if (bprm->file->f_op == NULL)
1085                 return -EACCES;
1086
1087         /* clear any previous set[ug]id data from a previous binary */
1088         bprm->cred->euid = current_euid();
1089         bprm->cred->egid = current_egid();
1090
1091         if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1092                 /* Set-uid? */
1093                 if (mode & S_ISUID) {
1094                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1095                         bprm->cred->euid = inode->i_uid;
1096                 }
1097
1098                 /* Set-gid? */
1099                 /*
1100                  * If setgid is set but no group execute bit then this
1101                  * is a candidate for mandatory locking, not a setgid
1102                  * executable.
1103                  */
1104                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1105                         bprm->per_clear |= PER_CLEAR_ON_SETID;
1106                         bprm->cred->egid = inode->i_gid;
1107                 }
1108         }
1109
1110         /* fill in binprm security blob */
1111         retval = security_bprm_set_creds(bprm);
1112         if (retval)
1113                 return retval;
1114         bprm->cred_prepared = 1;
1115
1116         memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1117         return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1118 }
1119
1120 EXPORT_SYMBOL(prepare_binprm);
1121
1122 /*
1123  * Arguments are '\0' separated strings found at the location bprm->p
1124  * points to; chop off the first by relocating brpm->p to right after
1125  * the first '\0' encountered.
1126  */
1127 int remove_arg_zero(struct linux_binprm *bprm)
1128 {
1129         int ret = 0;
1130         unsigned long offset;
1131         char *kaddr;
1132         struct page *page;
1133
1134         if (!bprm->argc)
1135                 return 0;
1136
1137         do {
1138                 offset = bprm->p & ~PAGE_MASK;
1139                 page = get_arg_page(bprm, bprm->p, 0);
1140                 if (!page) {
1141                         ret = -EFAULT;
1142                         goto out;
1143                 }
1144                 kaddr = kmap_atomic(page, KM_USER0);
1145
1146                 for (; offset < PAGE_SIZE && kaddr[offset];
1147                                 offset++, bprm->p++)
1148                         ;
1149
1150                 kunmap_atomic(kaddr, KM_USER0);
1151                 put_arg_page(page);
1152
1153                 if (offset == PAGE_SIZE)
1154                         free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1155         } while (offset == PAGE_SIZE);
1156
1157         bprm->p++;
1158         bprm->argc--;
1159         ret = 0;
1160
1161 out:
1162         return ret;
1163 }
1164 EXPORT_SYMBOL(remove_arg_zero);
1165
1166 /*
1167  * cycle the list of binary formats handler, until one recognizes the image
1168  */
1169 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1170 {
1171         unsigned int depth = bprm->recursion_depth;
1172         int try,retval;
1173         struct linux_binfmt *fmt;
1174
1175         retval = security_bprm_check(bprm);
1176         if (retval)
1177                 return retval;
1178         retval = ima_bprm_check(bprm);
1179         if (retval)
1180                 return retval;
1181
1182         /* kernel module loader fixup */
1183         /* so we don't try to load run modprobe in kernel space. */
1184         set_fs(USER_DS);
1185
1186         retval = audit_bprm(bprm);
1187         if (retval)
1188                 return retval;
1189
1190         retval = -ENOENT;
1191         for (try=0; try<2; try++) {
1192                 read_lock(&binfmt_lock);
1193                 list_for_each_entry(fmt, &formats, lh) {
1194                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1195                         if (!fn)
1196                                 continue;
1197                         if (!try_module_get(fmt->module))
1198                                 continue;
1199                         read_unlock(&binfmt_lock);
1200                         retval = fn(bprm, regs);
1201                         /*
1202                          * Restore the depth counter to its starting value
1203                          * in this call, so we don't have to rely on every
1204                          * load_binary function to restore it on return.
1205                          */
1206                         bprm->recursion_depth = depth;
1207                         if (retval >= 0) {
1208                                 if (depth == 0)
1209                                         tracehook_report_exec(fmt, bprm, regs);
1210                                 put_binfmt(fmt);
1211                                 allow_write_access(bprm->file);
1212                                 if (bprm->file)
1213                                         fput(bprm->file);
1214                                 bprm->file = NULL;
1215                                 current->did_exec = 1;
1216                                 proc_exec_connector(current);
1217                                 return retval;
1218                         }
1219                         read_lock(&binfmt_lock);
1220                         put_binfmt(fmt);
1221                         if (retval != -ENOEXEC || bprm->mm == NULL)
1222                                 break;
1223                         if (!bprm->file) {
1224                                 read_unlock(&binfmt_lock);
1225                                 return retval;
1226                         }
1227                 }
1228                 read_unlock(&binfmt_lock);
1229                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1230                         break;
1231 #ifdef CONFIG_MODULES
1232                 } else {
1233 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1234                         if (printable(bprm->buf[0]) &&
1235                             printable(bprm->buf[1]) &&
1236                             printable(bprm->buf[2]) &&
1237                             printable(bprm->buf[3]))
1238                                 break; /* -ENOEXEC */
1239                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1240 #endif
1241                 }
1242         }
1243         return retval;
1244 }
1245
1246 EXPORT_SYMBOL(search_binary_handler);
1247
1248 void free_bprm(struct linux_binprm *bprm)
1249 {
1250         free_arg_pages(bprm);
1251         if (bprm->cred)
1252                 abort_creds(bprm->cred);
1253         kfree(bprm);
1254 }
1255
1256 /*
1257  * sys_execve() executes a new program.
1258  */
1259 int do_execve(char * filename,
1260         char __user *__user *argv,
1261         char __user *__user *envp,
1262         struct pt_regs * regs)
1263 {
1264         struct linux_binprm *bprm;
1265         struct file *file;
1266         struct files_struct *displaced;
1267         int retval;
1268
1269         retval = unshare_files(&displaced);
1270         if (retval)
1271                 goto out_ret;
1272
1273         retval = -ENOMEM;
1274         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1275         if (!bprm)
1276                 goto out_files;
1277
1278         retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1279         if (retval < 0)
1280                 goto out_free;
1281
1282         retval = -ENOMEM;
1283         bprm->cred = prepare_exec_creds();
1284         if (!bprm->cred)
1285                 goto out_unlock;
1286         check_unsafe_exec(bprm);
1287
1288         file = open_exec(filename);
1289         retval = PTR_ERR(file);
1290         if (IS_ERR(file))
1291                 goto out_unlock;
1292
1293         sched_exec();
1294
1295         bprm->file = file;
1296         bprm->filename = filename;
1297         bprm->interp = filename;
1298
1299         retval = bprm_mm_init(bprm);
1300         if (retval)
1301                 goto out_file;
1302
1303         bprm->argc = count(argv, MAX_ARG_STRINGS);
1304         if ((retval = bprm->argc) < 0)
1305                 goto out;
1306
1307         bprm->envc = count(envp, MAX_ARG_STRINGS);
1308         if ((retval = bprm->envc) < 0)
1309                 goto out;
1310
1311         retval = prepare_binprm(bprm);
1312         if (retval < 0)
1313                 goto out;
1314
1315         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1316         if (retval < 0)
1317                 goto out;
1318
1319         bprm->exec = bprm->p;
1320         retval = copy_strings(bprm->envc, envp, bprm);
1321         if (retval < 0)
1322                 goto out;
1323
1324         retval = copy_strings(bprm->argc, argv, bprm);
1325         if (retval < 0)
1326                 goto out;
1327
1328         current->flags &= ~PF_KTHREAD;
1329         retval = search_binary_handler(bprm,regs);
1330         if (retval < 0)
1331                 goto out;
1332
1333         /* execve succeeded */
1334         mutex_unlock(&current->cred_exec_mutex);
1335         acct_update_integrals(current);
1336         free_bprm(bprm);
1337         if (displaced)
1338                 put_files_struct(displaced);
1339         return retval;
1340
1341 out:
1342         if (bprm->mm)
1343                 mmput (bprm->mm);
1344
1345 out_file:
1346         if (bprm->file) {
1347                 allow_write_access(bprm->file);
1348                 fput(bprm->file);
1349         }
1350
1351 out_unlock:
1352         mutex_unlock(&current->cred_exec_mutex);
1353
1354 out_free:
1355         free_bprm(bprm);
1356
1357 out_files:
1358         if (displaced)
1359                 reset_files_struct(displaced);
1360 out_ret:
1361         return retval;
1362 }
1363
1364 int set_binfmt(struct linux_binfmt *new)
1365 {
1366         struct linux_binfmt *old = current->binfmt;
1367
1368         if (new) {
1369                 if (!try_module_get(new->module))
1370                         return -1;
1371         }
1372         current->binfmt = new;
1373         if (old)
1374                 module_put(old->module);
1375         return 0;
1376 }
1377
1378 EXPORT_SYMBOL(set_binfmt);
1379
1380 /* format_corename will inspect the pattern parameter, and output a
1381  * name into corename, which must have space for at least
1382  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1383  */
1384 static int format_corename(char *corename, long signr)
1385 {
1386         const struct cred *cred = current_cred();
1387         const char *pat_ptr = core_pattern;
1388         int ispipe = (*pat_ptr == '|');
1389         char *out_ptr = corename;
1390         char *const out_end = corename + CORENAME_MAX_SIZE;
1391         int rc;
1392         int pid_in_pattern = 0;
1393
1394         /* Repeat as long as we have more pattern to process and more output
1395            space */
1396         while (*pat_ptr) {
1397                 if (*pat_ptr != '%') {
1398                         if (out_ptr == out_end)
1399                                 goto out;
1400                         *out_ptr++ = *pat_ptr++;
1401                 } else {
1402                         switch (*++pat_ptr) {
1403                         case 0:
1404                                 goto out;
1405                         /* Double percent, output one percent */
1406                         case '%':
1407                                 if (out_ptr == out_end)
1408                                         goto out;
1409                                 *out_ptr++ = '%';
1410                                 break;
1411                         /* pid */
1412                         case 'p':
1413                                 pid_in_pattern = 1;
1414                                 rc = snprintf(out_ptr, out_end - out_ptr,
1415                                               "%d", task_tgid_vnr(current));
1416                                 if (rc > out_end - out_ptr)
1417                                         goto out;
1418                                 out_ptr += rc;
1419                                 break;
1420                         /* uid */
1421                         case 'u':
1422                                 rc = snprintf(out_ptr, out_end - out_ptr,
1423                                               "%d", cred->uid);
1424                                 if (rc > out_end - out_ptr)
1425                                         goto out;
1426                                 out_ptr += rc;
1427                                 break;
1428                         /* gid */
1429                         case 'g':
1430                                 rc = snprintf(out_ptr, out_end - out_ptr,
1431                                               "%d", cred->gid);
1432                                 if (rc > out_end - out_ptr)
1433                                         goto out;
1434                                 out_ptr += rc;
1435                                 break;
1436                         /* signal that caused the coredump */
1437                         case 's':
1438                                 rc = snprintf(out_ptr, out_end - out_ptr,
1439                                               "%ld", signr);
1440                                 if (rc > out_end - out_ptr)
1441                                         goto out;
1442                                 out_ptr += rc;
1443                                 break;
1444                         /* UNIX time of coredump */
1445                         case 't': {
1446                                 struct timeval tv;
1447                                 do_gettimeofday(&tv);
1448                                 rc = snprintf(out_ptr, out_end - out_ptr,
1449                                               "%lu", tv.tv_sec);
1450                                 if (rc > out_end - out_ptr)
1451                                         goto out;
1452                                 out_ptr += rc;
1453                                 break;
1454                         }
1455                         /* hostname */
1456                         case 'h':
1457                                 down_read(&uts_sem);
1458                                 rc = snprintf(out_ptr, out_end - out_ptr,
1459                                               "%s", utsname()->nodename);
1460                                 up_read(&uts_sem);
1461                                 if (rc > out_end - out_ptr)
1462                                         goto out;
1463                                 out_ptr += rc;
1464                                 break;
1465                         /* executable */
1466                         case 'e':
1467                                 rc = snprintf(out_ptr, out_end - out_ptr,
1468                                               "%s", current->comm);
1469                                 if (rc > out_end - out_ptr)
1470                                         goto out;
1471                                 out_ptr += rc;
1472                                 break;
1473                         /* core limit size */
1474                         case 'c':
1475                                 rc = snprintf(out_ptr, out_end - out_ptr,
1476                                               "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1477                                 if (rc > out_end - out_ptr)
1478                                         goto out;
1479                                 out_ptr += rc;
1480                                 break;
1481                         default:
1482                                 break;
1483                         }
1484                         ++pat_ptr;
1485                 }
1486         }
1487         /* Backward compatibility with core_uses_pid:
1488          *
1489          * If core_pattern does not include a %p (as is the default)
1490          * and core_uses_pid is set, then .%pid will be appended to
1491          * the filename. Do not do this for piped commands. */
1492         if (!ispipe && !pid_in_pattern && core_uses_pid) {
1493                 rc = snprintf(out_ptr, out_end - out_ptr,
1494                               ".%d", task_tgid_vnr(current));
1495                 if (rc > out_end - out_ptr)
1496                         goto out;
1497                 out_ptr += rc;
1498         }
1499 out:
1500         *out_ptr = 0;
1501         return ispipe;
1502 }
1503
1504 static int zap_process(struct task_struct *start)
1505 {
1506         struct task_struct *t;
1507         int nr = 0;
1508
1509         start->signal->flags = SIGNAL_GROUP_EXIT;
1510         start->signal->group_stop_count = 0;
1511
1512         t = start;
1513         do {
1514                 if (t != current && t->mm) {
1515                         sigaddset(&t->pending.signal, SIGKILL);
1516                         signal_wake_up(t, 1);
1517                         nr++;
1518                 }
1519         } while_each_thread(start, t);
1520
1521         return nr;
1522 }
1523
1524 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1525                                 struct core_state *core_state, int exit_code)
1526 {
1527         struct task_struct *g, *p;
1528         unsigned long flags;
1529         int nr = -EAGAIN;
1530
1531         spin_lock_irq(&tsk->sighand->siglock);
1532         if (!signal_group_exit(tsk->signal)) {
1533                 mm->core_state = core_state;
1534                 tsk->signal->group_exit_code = exit_code;
1535                 nr = zap_process(tsk);
1536         }
1537         spin_unlock_irq(&tsk->sighand->siglock);
1538         if (unlikely(nr < 0))
1539                 return nr;
1540
1541         if (atomic_read(&mm->mm_users) == nr + 1)
1542                 goto done;
1543         /*
1544          * We should find and kill all tasks which use this mm, and we should
1545          * count them correctly into ->nr_threads. We don't take tasklist
1546          * lock, but this is safe wrt:
1547          *
1548          * fork:
1549          *      None of sub-threads can fork after zap_process(leader). All
1550          *      processes which were created before this point should be
1551          *      visible to zap_threads() because copy_process() adds the new
1552          *      process to the tail of init_task.tasks list, and lock/unlock
1553          *      of ->siglock provides a memory barrier.
1554          *
1555          * do_exit:
1556          *      The caller holds mm->mmap_sem. This means that the task which
1557          *      uses this mm can't pass exit_mm(), so it can't exit or clear
1558          *      its ->mm.
1559          *
1560          * de_thread:
1561          *      It does list_replace_rcu(&leader->tasks, &current->tasks),
1562          *      we must see either old or new leader, this does not matter.
1563          *      However, it can change p->sighand, so lock_task_sighand(p)
1564          *      must be used. Since p->mm != NULL and we hold ->mmap_sem
1565          *      it can't fail.
1566          *
1567          *      Note also that "g" can be the old leader with ->mm == NULL
1568          *      and already unhashed and thus removed from ->thread_group.
1569          *      This is OK, __unhash_process()->list_del_rcu() does not
1570          *      clear the ->next pointer, we will find the new leader via
1571          *      next_thread().
1572          */
1573         rcu_read_lock();
1574         for_each_process(g) {
1575                 if (g == tsk->group_leader)
1576                         continue;
1577                 if (g->flags & PF_KTHREAD)
1578                         continue;
1579                 p = g;
1580                 do {
1581                         if (p->mm) {
1582                                 if (unlikely(p->mm == mm)) {
1583                                         lock_task_sighand(p, &flags);
1584                                         nr += zap_process(p);
1585                                         unlock_task_sighand(p, &flags);
1586                                 }
1587                                 break;
1588                         }
1589                 } while_each_thread(g, p);
1590         }
1591         rcu_read_unlock();
1592 done:
1593         atomic_set(&core_state->nr_threads, nr);
1594         return nr;
1595 }
1596
1597 static int coredump_wait(int exit_code, struct core_state *core_state)
1598 {
1599         struct task_struct *tsk = current;
1600         struct mm_struct *mm = tsk->mm;
1601         struct completion *vfork_done;
1602         int core_waiters;
1603
1604         init_completion(&core_state->startup);
1605         core_state->dumper.task = tsk;
1606         core_state->dumper.next = NULL;
1607         core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1608         up_write(&mm->mmap_sem);
1609
1610         if (unlikely(core_waiters < 0))
1611                 goto fail;
1612
1613         /*
1614          * Make sure nobody is waiting for us to release the VM,
1615          * otherwise we can deadlock when we wait on each other
1616          */
1617         vfork_done = tsk->vfork_done;
1618         if (vfork_done) {
1619                 tsk->vfork_done = NULL;
1620                 complete(vfork_done);
1621         }
1622
1623         if (core_waiters)
1624                 wait_for_completion(&core_state->startup);
1625 fail:
1626         return core_waiters;
1627 }
1628
1629 static void coredump_finish(struct mm_struct *mm)
1630 {
1631         struct core_thread *curr, *next;
1632         struct task_struct *task;
1633
1634         next = mm->core_state->dumper.next;
1635         while ((curr = next) != NULL) {
1636                 next = curr->next;
1637                 task = curr->task;
1638                 /*
1639                  * see exit_mm(), curr->task must not see
1640                  * ->task == NULL before we read ->next.
1641                  */
1642                 smp_mb();
1643                 curr->task = NULL;
1644                 wake_up_process(task);
1645         }
1646
1647         mm->core_state = NULL;
1648 }
1649
1650 /*
1651  * set_dumpable converts traditional three-value dumpable to two flags and
1652  * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
1653  * these bits are not changed atomically.  So get_dumpable can observe the
1654  * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
1655  * return either old dumpable or new one by paying attention to the order of
1656  * modifying the bits.
1657  *
1658  * dumpable |   mm->flags (binary)
1659  * old  new | initial interim  final
1660  * ---------+-----------------------
1661  *  0    1  |   00      01      01
1662  *  0    2  |   00      10(*)   11
1663  *  1    0  |   01      00      00
1664  *  1    2  |   01      11      11
1665  *  2    0  |   11      10(*)   00
1666  *  2    1  |   11      11      01
1667  *
1668  * (*) get_dumpable regards interim value of 10 as 11.
1669  */
1670 void set_dumpable(struct mm_struct *mm, int value)
1671 {
1672         switch (value) {
1673         case 0:
1674                 clear_bit(MMF_DUMPABLE, &mm->flags);
1675                 smp_wmb();
1676                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1677                 break;
1678         case 1:
1679                 set_bit(MMF_DUMPABLE, &mm->flags);
1680                 smp_wmb();
1681                 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1682                 break;
1683         case 2:
1684                 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1685                 smp_wmb();
1686                 set_bit(MMF_DUMPABLE, &mm->flags);
1687                 break;
1688         }
1689 }
1690
1691 int get_dumpable(struct mm_struct *mm)
1692 {
1693         int ret;
1694
1695         ret = mm->flags & 0x3;
1696         return (ret >= 2) ? 2 : ret;
1697 }
1698
1699 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1700 {
1701         struct core_state core_state;
1702         char corename[CORENAME_MAX_SIZE + 1];
1703         struct mm_struct *mm = current->mm;
1704         struct linux_binfmt * binfmt;
1705         struct inode * inode;
1706         struct file * file;
1707         const struct cred *old_cred;
1708         struct cred *cred;
1709         int retval = 0;
1710         int flag = 0;
1711         int ispipe = 0;
1712         unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1713         char **helper_argv = NULL;
1714         int helper_argc = 0;
1715         char *delimit;
1716
1717         audit_core_dumps(signr);
1718
1719         binfmt = current->binfmt;
1720         if (!binfmt || !binfmt->core_dump)
1721                 goto fail;
1722
1723         cred = prepare_creds();
1724         if (!cred) {
1725                 retval = -ENOMEM;
1726                 goto fail;
1727         }
1728
1729         down_write(&mm->mmap_sem);
1730         /*
1731          * If another thread got here first, or we are not dumpable, bail out.
1732          */
1733         if (mm->core_state || !get_dumpable(mm)) {
1734                 up_write(&mm->mmap_sem);
1735                 put_cred(cred);
1736                 goto fail;
1737         }
1738
1739         /*
1740          *      We cannot trust fsuid as being the "true" uid of the
1741          *      process nor do we know its entire history. We only know it
1742          *      was tainted so we dump it as root in mode 2.
1743          */
1744         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */
1745                 flag = O_EXCL;          /* Stop rewrite attacks */
1746                 cred->fsuid = 0;        /* Dump root private */
1747         }
1748
1749         retval = coredump_wait(exit_code, &core_state);
1750         if (retval < 0) {
1751                 put_cred(cred);
1752                 goto fail;
1753         }
1754
1755         old_cred = override_creds(cred);
1756
1757         /*
1758          * Clear any false indication of pending signals that might
1759          * be seen by the filesystem code called to write the core file.
1760          */
1761         clear_thread_flag(TIF_SIGPENDING);
1762
1763         /*
1764          * lock_kernel() because format_corename() is controlled by sysctl, which
1765          * uses lock_kernel()
1766          */
1767         lock_kernel();
1768         ispipe = format_corename(corename, signr);
1769         unlock_kernel();
1770         /*
1771          * Don't bother to check the RLIMIT_CORE value if core_pattern points
1772          * to a pipe.  Since we're not writing directly to the filesystem
1773          * RLIMIT_CORE doesn't really apply, as no actual core file will be
1774          * created unless the pipe reader choses to write out the core file
1775          * at which point file size limits and permissions will be imposed
1776          * as it does with any other process
1777          */
1778         if ((!ispipe) && (core_limit < binfmt->min_coredump))
1779                 goto fail_unlock;
1780
1781         if (ispipe) {
1782                 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1783                 if (!helper_argv) {
1784                         printk(KERN_WARNING "%s failed to allocate memory\n",
1785                                __func__);
1786                         goto fail_unlock;
1787                 }
1788                 /* Terminate the string before the first option */
1789                 delimit = strchr(corename, ' ');
1790                 if (delimit)
1791                         *delimit = '\0';
1792                 delimit = strrchr(helper_argv[0], '/');
1793                 if (delimit)
1794                         delimit++;
1795                 else
1796                         delimit = helper_argv[0];
1797                 if (!strcmp(delimit, current->comm)) {
1798                         printk(KERN_NOTICE "Recursive core dump detected, "
1799                                         "aborting\n");
1800                         goto fail_unlock;
1801                 }
1802
1803                 core_limit = RLIM_INFINITY;
1804
1805                 /* SIGPIPE can happen, but it's just never processed */
1806                 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1807                                 &file)) {
1808                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1809                                corename);
1810                         goto fail_unlock;
1811                 }
1812         } else
1813                 file = filp_open(corename,
1814                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1815                                  0600);
1816         if (IS_ERR(file))
1817                 goto fail_unlock;
1818         inode = file->f_path.dentry->d_inode;
1819         if (inode->i_nlink > 1)
1820                 goto close_fail;        /* multiple links - don't dump */
1821         if (!ispipe && d_unhashed(file->f_path.dentry))
1822                 goto close_fail;
1823
1824         /* AK: actually i see no reason to not allow this for named pipes etc.,
1825            but keep the previous behaviour for now. */
1826         if (!ispipe && !S_ISREG(inode->i_mode))
1827                 goto close_fail;
1828         /*
1829          * Dont allow local users get cute and trick others to coredump
1830          * into their pre-created files:
1831          */
1832         if (inode->i_uid != current_fsuid())
1833                 goto close_fail;
1834         if (!file->f_op)
1835                 goto close_fail;
1836         if (!file->f_op->write)
1837                 goto close_fail;
1838         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1839                 goto close_fail;
1840
1841         retval = binfmt->core_dump(signr, regs, file, core_limit);
1842
1843         if (retval)
1844                 current->signal->group_exit_code |= 0x80;
1845 close_fail:
1846         filp_close(file, NULL);
1847 fail_unlock:
1848         if (helper_argv)
1849                 argv_free(helper_argv);
1850
1851         revert_creds(old_cred);
1852         put_cred(cred);
1853         coredump_finish(mm);
1854 fail:
1855         return;
1856 }