smp_call_function_single(): be slightly less stupid, fix #2
[linux-2.6/mini2440.git] / fs / exec.c
blob71a6efe5d8bd572455c1305a07734af70194d581
1 /*
2 * linux/fs/exec.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
8 * #!-checking implemented by tytso.
9 */
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.
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.
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.
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/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>
56 #include <asm/uaccess.h>
57 #include <asm/mmu_context.h>
58 #include <asm/tlb.h>
59 #include "internal.h"
61 int core_uses_pid;
62 char core_pattern[CORENAME_MAX_SIZE] = "core";
63 int suid_dumpable = 0;
65 /* The maximal length of core_pattern is also specified in sysctl.c */
67 static LIST_HEAD(formats);
68 static DEFINE_RWLOCK(binfmt_lock);
70 int register_binfmt(struct linux_binfmt * fmt)
72 if (!fmt)
73 return -EINVAL;
74 write_lock(&binfmt_lock);
75 list_add(&fmt->lh, &formats);
76 write_unlock(&binfmt_lock);
77 return 0;
80 EXPORT_SYMBOL(register_binfmt);
82 void unregister_binfmt(struct linux_binfmt * fmt)
84 write_lock(&binfmt_lock);
85 list_del(&fmt->lh);
86 write_unlock(&binfmt_lock);
89 EXPORT_SYMBOL(unregister_binfmt);
91 static inline void put_binfmt(struct linux_binfmt * fmt)
93 module_put(fmt->module);
97 * Note that a shared library must be both readable and executable due to
98 * security reasons.
100 * Also note that we take the address to load from from the file itself.
102 asmlinkage long sys_uselib(const char __user * library)
104 struct file *file;
105 struct nameidata nd;
106 char *tmp = getname(library);
107 int error = PTR_ERR(tmp);
109 if (!IS_ERR(tmp)) {
110 error = path_lookup_open(AT_FDCWD, tmp,
111 LOOKUP_FOLLOW, &nd,
112 FMODE_READ|FMODE_EXEC);
113 putname(tmp);
115 if (error)
116 goto out;
118 error = -EINVAL;
119 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
120 goto exit;
122 error = -EACCES;
123 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
124 goto exit;
126 error = inode_permission(nd.path.dentry->d_inode,
127 MAY_READ | MAY_EXEC | MAY_OPEN);
128 if (error)
129 goto exit;
131 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
132 error = PTR_ERR(file);
133 if (IS_ERR(file))
134 goto out;
136 fsnotify_open(file->f_path.dentry);
138 error = -ENOEXEC;
139 if(file->f_op) {
140 struct linux_binfmt * fmt;
142 read_lock(&binfmt_lock);
143 list_for_each_entry(fmt, &formats, lh) {
144 if (!fmt->load_shlib)
145 continue;
146 if (!try_module_get(fmt->module))
147 continue;
148 read_unlock(&binfmt_lock);
149 error = fmt->load_shlib(file);
150 read_lock(&binfmt_lock);
151 put_binfmt(fmt);
152 if (error != -ENOEXEC)
153 break;
155 read_unlock(&binfmt_lock);
157 fput(file);
158 out:
159 return error;
160 exit:
161 release_open_intent(&nd);
162 path_put(&nd.path);
163 goto out;
166 #ifdef CONFIG_MMU
168 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
169 int write)
171 struct page *page;
172 int ret;
174 #ifdef CONFIG_STACK_GROWSUP
175 if (write) {
176 ret = expand_stack_downwards(bprm->vma, pos);
177 if (ret < 0)
178 return NULL;
180 #endif
181 ret = get_user_pages(current, bprm->mm, pos,
182 1, write, 1, &page, NULL);
183 if (ret <= 0)
184 return NULL;
186 if (write) {
187 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
188 struct rlimit *rlim;
191 * We've historically supported up to 32 pages (ARG_MAX)
192 * of argument strings even with small stacks
194 if (size <= ARG_MAX)
195 return page;
198 * Limit to 1/4-th the stack size for the argv+env strings.
199 * This ensures that:
200 * - the remaining binfmt code will not run out of stack space,
201 * - the program will have a reasonable amount of stack left
202 * to work from.
204 rlim = current->signal->rlim;
205 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
206 put_page(page);
207 return NULL;
211 return page;
214 static void put_arg_page(struct page *page)
216 put_page(page);
219 static void free_arg_page(struct linux_binprm *bprm, int i)
223 static void free_arg_pages(struct linux_binprm *bprm)
227 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
228 struct page *page)
230 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
233 static int __bprm_mm_init(struct linux_binprm *bprm)
235 int err;
236 struct vm_area_struct *vma = NULL;
237 struct mm_struct *mm = bprm->mm;
239 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
240 if (!vma)
241 return -ENOMEM;
243 down_write(&mm->mmap_sem);
244 vma->vm_mm = mm;
247 * Place the stack at the largest stack address the architecture
248 * supports. Later, we'll move this to an appropriate place. We don't
249 * use STACK_TOP because that can depend on attributes which aren't
250 * configured yet.
252 vma->vm_end = STACK_TOP_MAX;
253 vma->vm_start = vma->vm_end - PAGE_SIZE;
254 vma->vm_flags = VM_STACK_FLAGS;
255 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
256 err = insert_vm_struct(mm, vma);
257 if (err)
258 goto err;
260 mm->stack_vm = mm->total_vm = 1;
261 up_write(&mm->mmap_sem);
262 bprm->p = vma->vm_end - sizeof(void *);
263 return 0;
264 err:
265 up_write(&mm->mmap_sem);
266 bprm->vma = NULL;
267 kmem_cache_free(vm_area_cachep, vma);
268 return err;
271 static bool valid_arg_len(struct linux_binprm *bprm, long len)
273 return len <= MAX_ARG_STRLEN;
276 #else
278 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
279 int write)
281 struct page *page;
283 page = bprm->page[pos / PAGE_SIZE];
284 if (!page && write) {
285 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
286 if (!page)
287 return NULL;
288 bprm->page[pos / PAGE_SIZE] = page;
291 return page;
294 static void put_arg_page(struct page *page)
298 static void free_arg_page(struct linux_binprm *bprm, int i)
300 if (bprm->page[i]) {
301 __free_page(bprm->page[i]);
302 bprm->page[i] = NULL;
306 static void free_arg_pages(struct linux_binprm *bprm)
308 int i;
310 for (i = 0; i < MAX_ARG_PAGES; i++)
311 free_arg_page(bprm, i);
314 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
315 struct page *page)
319 static int __bprm_mm_init(struct linux_binprm *bprm)
321 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
322 return 0;
325 static bool valid_arg_len(struct linux_binprm *bprm, long len)
327 return len <= bprm->p;
330 #endif /* CONFIG_MMU */
333 * Create a new mm_struct and populate it with a temporary stack
334 * vm_area_struct. We don't have enough context at this point to set the stack
335 * flags, permissions, and offset, so we use temporary values. We'll update
336 * them later in setup_arg_pages().
338 int bprm_mm_init(struct linux_binprm *bprm)
340 int err;
341 struct mm_struct *mm = NULL;
343 bprm->mm = mm = mm_alloc();
344 err = -ENOMEM;
345 if (!mm)
346 goto err;
348 err = init_new_context(current, mm);
349 if (err)
350 goto err;
352 err = __bprm_mm_init(bprm);
353 if (err)
354 goto err;
356 return 0;
358 err:
359 if (mm) {
360 bprm->mm = NULL;
361 mmdrop(mm);
364 return err;
368 * count() counts the number of strings in array ARGV.
370 static int count(char __user * __user * argv, int max)
372 int i = 0;
374 if (argv != NULL) {
375 for (;;) {
376 char __user * p;
378 if (get_user(p, argv))
379 return -EFAULT;
380 if (!p)
381 break;
382 argv++;
383 if (i++ >= max)
384 return -E2BIG;
385 cond_resched();
388 return i;
392 * 'copy_strings()' copies argument/environment strings from the old
393 * processes's memory to the new process's stack. The call to get_user_pages()
394 * ensures the destination page is created and not swapped out.
396 static int copy_strings(int argc, char __user * __user * argv,
397 struct linux_binprm *bprm)
399 struct page *kmapped_page = NULL;
400 char *kaddr = NULL;
401 unsigned long kpos = 0;
402 int ret;
404 while (argc-- > 0) {
405 char __user *str;
406 int len;
407 unsigned long pos;
409 if (get_user(str, argv+argc) ||
410 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
411 ret = -EFAULT;
412 goto out;
415 if (!valid_arg_len(bprm, len)) {
416 ret = -E2BIG;
417 goto out;
420 /* We're going to work our way backwords. */
421 pos = bprm->p;
422 str += len;
423 bprm->p -= len;
425 while (len > 0) {
426 int offset, bytes_to_copy;
428 offset = pos % PAGE_SIZE;
429 if (offset == 0)
430 offset = PAGE_SIZE;
432 bytes_to_copy = offset;
433 if (bytes_to_copy > len)
434 bytes_to_copy = len;
436 offset -= bytes_to_copy;
437 pos -= bytes_to_copy;
438 str -= bytes_to_copy;
439 len -= bytes_to_copy;
441 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
442 struct page *page;
444 page = get_arg_page(bprm, pos, 1);
445 if (!page) {
446 ret = -E2BIG;
447 goto out;
450 if (kmapped_page) {
451 flush_kernel_dcache_page(kmapped_page);
452 kunmap(kmapped_page);
453 put_arg_page(kmapped_page);
455 kmapped_page = page;
456 kaddr = kmap(kmapped_page);
457 kpos = pos & PAGE_MASK;
458 flush_arg_page(bprm, kpos, kmapped_page);
460 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
461 ret = -EFAULT;
462 goto out;
466 ret = 0;
467 out:
468 if (kmapped_page) {
469 flush_kernel_dcache_page(kmapped_page);
470 kunmap(kmapped_page);
471 put_arg_page(kmapped_page);
473 return ret;
477 * Like copy_strings, but get argv and its values from kernel memory.
479 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
481 int r;
482 mm_segment_t oldfs = get_fs();
483 set_fs(KERNEL_DS);
484 r = copy_strings(argc, (char __user * __user *)argv, bprm);
485 set_fs(oldfs);
486 return r;
488 EXPORT_SYMBOL(copy_strings_kernel);
490 #ifdef CONFIG_MMU
493 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
494 * the binfmt code determines where the new stack should reside, we shift it to
495 * its final location. The process proceeds as follows:
497 * 1) Use shift to calculate the new vma endpoints.
498 * 2) Extend vma to cover both the old and new ranges. This ensures the
499 * arguments passed to subsequent functions are consistent.
500 * 3) Move vma's page tables to the new range.
501 * 4) Free up any cleared pgd range.
502 * 5) Shrink the vma to cover only the new range.
504 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
506 struct mm_struct *mm = vma->vm_mm;
507 unsigned long old_start = vma->vm_start;
508 unsigned long old_end = vma->vm_end;
509 unsigned long length = old_end - old_start;
510 unsigned long new_start = old_start - shift;
511 unsigned long new_end = old_end - shift;
512 struct mmu_gather *tlb;
514 BUG_ON(new_start > new_end);
517 * ensure there are no vmas between where we want to go
518 * and where we are
520 if (vma != find_vma(mm, new_start))
521 return -EFAULT;
524 * cover the whole range: [new_start, old_end)
526 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
529 * move the page tables downwards, on failure we rely on
530 * process cleanup to remove whatever mess we made.
532 if (length != move_page_tables(vma, old_start,
533 vma, new_start, length))
534 return -ENOMEM;
536 lru_add_drain();
537 tlb = tlb_gather_mmu(mm, 0);
538 if (new_end > old_start) {
540 * when the old and new regions overlap clear from new_end.
542 free_pgd_range(tlb, new_end, old_end, new_end,
543 vma->vm_next ? vma->vm_next->vm_start : 0);
544 } else {
546 * otherwise, clean from old_start; this is done to not touch
547 * the address space in [new_end, old_start) some architectures
548 * have constraints on va-space that make this illegal (IA64) -
549 * for the others its just a little faster.
551 free_pgd_range(tlb, old_start, old_end, new_end,
552 vma->vm_next ? vma->vm_next->vm_start : 0);
554 tlb_finish_mmu(tlb, new_end, old_end);
557 * shrink the vma to just the new range.
559 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
561 return 0;
564 #define EXTRA_STACK_VM_PAGES 20 /* random */
567 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
568 * the stack is optionally relocated, and some extra space is added.
570 int setup_arg_pages(struct linux_binprm *bprm,
571 unsigned long stack_top,
572 int executable_stack)
574 unsigned long ret;
575 unsigned long stack_shift;
576 struct mm_struct *mm = current->mm;
577 struct vm_area_struct *vma = bprm->vma;
578 struct vm_area_struct *prev = NULL;
579 unsigned long vm_flags;
580 unsigned long stack_base;
582 #ifdef CONFIG_STACK_GROWSUP
583 /* Limit stack size to 1GB */
584 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
585 if (stack_base > (1 << 30))
586 stack_base = 1 << 30;
588 /* Make sure we didn't let the argument array grow too large. */
589 if (vma->vm_end - vma->vm_start > stack_base)
590 return -ENOMEM;
592 stack_base = PAGE_ALIGN(stack_top - stack_base);
594 stack_shift = vma->vm_start - stack_base;
595 mm->arg_start = bprm->p - stack_shift;
596 bprm->p = vma->vm_end - stack_shift;
597 #else
598 stack_top = arch_align_stack(stack_top);
599 stack_top = PAGE_ALIGN(stack_top);
600 stack_shift = vma->vm_end - stack_top;
602 bprm->p -= stack_shift;
603 mm->arg_start = bprm->p;
604 #endif
606 if (bprm->loader)
607 bprm->loader -= stack_shift;
608 bprm->exec -= stack_shift;
610 down_write(&mm->mmap_sem);
611 vm_flags = VM_STACK_FLAGS;
614 * Adjust stack execute permissions; explicitly enable for
615 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
616 * (arch default) otherwise.
618 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
619 vm_flags |= VM_EXEC;
620 else if (executable_stack == EXSTACK_DISABLE_X)
621 vm_flags &= ~VM_EXEC;
622 vm_flags |= mm->def_flags;
624 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
625 vm_flags);
626 if (ret)
627 goto out_unlock;
628 BUG_ON(prev != vma);
630 /* Move stack pages down in memory. */
631 if (stack_shift) {
632 ret = shift_arg_pages(vma, stack_shift);
633 if (ret) {
634 up_write(&mm->mmap_sem);
635 return ret;
639 #ifdef CONFIG_STACK_GROWSUP
640 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
641 #else
642 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
643 #endif
644 ret = expand_stack(vma, stack_base);
645 if (ret)
646 ret = -EFAULT;
648 out_unlock:
649 up_write(&mm->mmap_sem);
650 return 0;
652 EXPORT_SYMBOL(setup_arg_pages);
654 #endif /* CONFIG_MMU */
656 struct file *open_exec(const char *name)
658 struct nameidata nd;
659 struct file *file;
660 int err;
662 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
663 FMODE_READ|FMODE_EXEC);
664 if (err)
665 goto out;
667 err = -EACCES;
668 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
669 goto out_path_put;
671 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
672 goto out_path_put;
674 err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
675 if (err)
676 goto out_path_put;
678 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
679 if (IS_ERR(file))
680 return file;
682 fsnotify_open(file->f_path.dentry);
684 err = deny_write_access(file);
685 if (err) {
686 fput(file);
687 goto out;
690 return file;
692 out_path_put:
693 release_open_intent(&nd);
694 path_put(&nd.path);
695 out:
696 return ERR_PTR(err);
698 EXPORT_SYMBOL(open_exec);
700 int kernel_read(struct file *file, unsigned long offset,
701 char *addr, unsigned long count)
703 mm_segment_t old_fs;
704 loff_t pos = offset;
705 int result;
707 old_fs = get_fs();
708 set_fs(get_ds());
709 /* The cast to a user pointer is valid due to the set_fs() */
710 result = vfs_read(file, (void __user *)addr, count, &pos);
711 set_fs(old_fs);
712 return result;
715 EXPORT_SYMBOL(kernel_read);
717 static int exec_mmap(struct mm_struct *mm)
719 struct task_struct *tsk;
720 struct mm_struct * old_mm, *active_mm;
722 /* Notify parent that we're no longer interested in the old VM */
723 tsk = current;
724 old_mm = current->mm;
725 mm_release(tsk, old_mm);
727 if (old_mm) {
729 * Make sure that if there is a core dump in progress
730 * for the old mm, we get out and die instead of going
731 * through with the exec. We must hold mmap_sem around
732 * checking core_state and changing tsk->mm.
734 down_read(&old_mm->mmap_sem);
735 if (unlikely(old_mm->core_state)) {
736 up_read(&old_mm->mmap_sem);
737 return -EINTR;
740 task_lock(tsk);
741 active_mm = tsk->active_mm;
742 tsk->mm = mm;
743 tsk->active_mm = mm;
744 activate_mm(active_mm, mm);
745 task_unlock(tsk);
746 arch_pick_mmap_layout(mm);
747 if (old_mm) {
748 up_read(&old_mm->mmap_sem);
749 BUG_ON(active_mm != old_mm);
750 mm_update_next_owner(old_mm);
751 mmput(old_mm);
752 return 0;
754 mmdrop(active_mm);
755 return 0;
759 * This function makes sure the current process has its own signal table,
760 * so that flush_signal_handlers can later reset the handlers without
761 * disturbing other processes. (Other processes might share the signal
762 * table via the CLONE_SIGHAND option to clone().)
764 static int de_thread(struct task_struct *tsk)
766 struct signal_struct *sig = tsk->signal;
767 struct sighand_struct *oldsighand = tsk->sighand;
768 spinlock_t *lock = &oldsighand->siglock;
769 int count;
771 if (thread_group_empty(tsk))
772 goto no_thread_group;
775 * Kill all other threads in the thread group.
777 spin_lock_irq(lock);
778 if (signal_group_exit(sig)) {
780 * Another group action in progress, just
781 * return so that the signal is processed.
783 spin_unlock_irq(lock);
784 return -EAGAIN;
786 sig->group_exit_task = tsk;
787 zap_other_threads(tsk);
789 /* Account for the thread group leader hanging around: */
790 count = thread_group_leader(tsk) ? 1 : 2;
791 sig->notify_count = count;
792 while (atomic_read(&sig->count) > count) {
793 __set_current_state(TASK_UNINTERRUPTIBLE);
794 spin_unlock_irq(lock);
795 schedule();
796 spin_lock_irq(lock);
798 spin_unlock_irq(lock);
801 * At this point all other threads have exited, all we have to
802 * do is to wait for the thread group leader to become inactive,
803 * and to assume its PID:
805 if (!thread_group_leader(tsk)) {
806 struct task_struct *leader = tsk->group_leader;
808 sig->notify_count = -1; /* for exit_notify() */
809 for (;;) {
810 write_lock_irq(&tasklist_lock);
811 if (likely(leader->exit_state))
812 break;
813 __set_current_state(TASK_UNINTERRUPTIBLE);
814 write_unlock_irq(&tasklist_lock);
815 schedule();
819 * The only record we have of the real-time age of a
820 * process, regardless of execs it's done, is start_time.
821 * All the past CPU time is accumulated in signal_struct
822 * from sister threads now dead. But in this non-leader
823 * exec, nothing survives from the original leader thread,
824 * whose birth marks the true age of this process now.
825 * When we take on its identity by switching to its PID, we
826 * also take its birthdate (always earlier than our own).
828 tsk->start_time = leader->start_time;
830 BUG_ON(!same_thread_group(leader, tsk));
831 BUG_ON(has_group_leader_pid(tsk));
833 * An exec() starts a new thread group with the
834 * TGID of the previous thread group. Rehash the
835 * two threads with a switched PID, and release
836 * the former thread group leader:
839 /* Become a process group leader with the old leader's pid.
840 * The old leader becomes a thread of the this thread group.
841 * Note: The old leader also uses this pid until release_task
842 * is called. Odd but simple and correct.
844 detach_pid(tsk, PIDTYPE_PID);
845 tsk->pid = leader->pid;
846 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
847 transfer_pid(leader, tsk, PIDTYPE_PGID);
848 transfer_pid(leader, tsk, PIDTYPE_SID);
849 list_replace_rcu(&leader->tasks, &tsk->tasks);
851 tsk->group_leader = tsk;
852 leader->group_leader = tsk;
854 tsk->exit_signal = SIGCHLD;
856 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
857 leader->exit_state = EXIT_DEAD;
858 write_unlock_irq(&tasklist_lock);
860 release_task(leader);
863 sig->group_exit_task = NULL;
864 sig->notify_count = 0;
866 no_thread_group:
867 exit_itimers(sig);
868 flush_itimer_signals();
870 if (atomic_read(&oldsighand->count) != 1) {
871 struct sighand_struct *newsighand;
873 * This ->sighand is shared with the CLONE_SIGHAND
874 * but not CLONE_THREAD task, switch to the new one.
876 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
877 if (!newsighand)
878 return -ENOMEM;
880 atomic_set(&newsighand->count, 1);
881 memcpy(newsighand->action, oldsighand->action,
882 sizeof(newsighand->action));
884 write_lock_irq(&tasklist_lock);
885 spin_lock(&oldsighand->siglock);
886 rcu_assign_pointer(tsk->sighand, newsighand);
887 spin_unlock(&oldsighand->siglock);
888 write_unlock_irq(&tasklist_lock);
890 __cleanup_sighand(oldsighand);
893 BUG_ON(!thread_group_leader(tsk));
894 return 0;
898 * These functions flushes out all traces of the currently running executable
899 * so that a new one can be started
901 static void flush_old_files(struct files_struct * files)
903 long j = -1;
904 struct fdtable *fdt;
906 spin_lock(&files->file_lock);
907 for (;;) {
908 unsigned long set, i;
910 j++;
911 i = j * __NFDBITS;
912 fdt = files_fdtable(files);
913 if (i >= fdt->max_fds)
914 break;
915 set = fdt->close_on_exec->fds_bits[j];
916 if (!set)
917 continue;
918 fdt->close_on_exec->fds_bits[j] = 0;
919 spin_unlock(&files->file_lock);
920 for ( ; set ; i++,set >>= 1) {
921 if (set & 1) {
922 sys_close(i);
925 spin_lock(&files->file_lock);
928 spin_unlock(&files->file_lock);
931 char *get_task_comm(char *buf, struct task_struct *tsk)
933 /* buf must be at least sizeof(tsk->comm) in size */
934 task_lock(tsk);
935 strncpy(buf, tsk->comm, sizeof(tsk->comm));
936 task_unlock(tsk);
937 return buf;
940 void set_task_comm(struct task_struct *tsk, char *buf)
942 task_lock(tsk);
943 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
944 task_unlock(tsk);
947 int flush_old_exec(struct linux_binprm * bprm)
949 char * name;
950 int i, ch, retval;
951 char tcomm[sizeof(current->comm)];
954 * Make sure we have a private signal table and that
955 * we are unassociated from the previous thread group.
957 retval = de_thread(current);
958 if (retval)
959 goto out;
961 set_mm_exe_file(bprm->mm, bprm->file);
964 * Release all of the old mmap stuff
966 retval = exec_mmap(bprm->mm);
967 if (retval)
968 goto out;
970 bprm->mm = NULL; /* We're using it now */
972 /* This is the point of no return */
973 current->sas_ss_sp = current->sas_ss_size = 0;
975 if (current_euid() == current_uid() && current_egid() == current_gid())
976 set_dumpable(current->mm, 1);
977 else
978 set_dumpable(current->mm, suid_dumpable);
980 name = bprm->filename;
982 /* Copies the binary name from after last slash */
983 for (i=0; (ch = *(name++)) != '\0';) {
984 if (ch == '/')
985 i = 0; /* overwrite what we wrote */
986 else
987 if (i < (sizeof(tcomm) - 1))
988 tcomm[i++] = ch;
990 tcomm[i] = '\0';
991 set_task_comm(current, tcomm);
993 current->flags &= ~PF_RANDOMIZE;
994 flush_thread();
996 /* Set the new mm task size. We have to do that late because it may
997 * depend on TIF_32BIT which is only updated in flush_thread() on
998 * some architectures like powerpc
1000 current->mm->task_size = TASK_SIZE;
1002 /* install the new credentials */
1003 if (bprm->cred->uid != current_euid() ||
1004 bprm->cred->gid != current_egid()) {
1005 current->pdeath_signal = 0;
1006 } else if (file_permission(bprm->file, MAY_READ) ||
1007 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1008 set_dumpable(current->mm, suid_dumpable);
1011 current->personality &= ~bprm->per_clear;
1013 /* An exec changes our domain. We are no longer part of the thread
1014 group */
1016 current->self_exec_id++;
1018 flush_signal_handlers(current, 0);
1019 flush_old_files(current->files);
1021 return 0;
1023 out:
1024 return retval;
1027 EXPORT_SYMBOL(flush_old_exec);
1030 * install the new credentials for this executable
1032 void install_exec_creds(struct linux_binprm *bprm)
1034 security_bprm_committing_creds(bprm);
1036 commit_creds(bprm->cred);
1037 bprm->cred = NULL;
1039 /* cred_exec_mutex must be held at least to this point to prevent
1040 * ptrace_attach() from altering our determination of the task's
1041 * credentials; any time after this it may be unlocked */
1043 security_bprm_committed_creds(bprm);
1045 EXPORT_SYMBOL(install_exec_creds);
1048 * determine how safe it is to execute the proposed program
1049 * - the caller must hold current->cred_exec_mutex to protect against
1050 * PTRACE_ATTACH
1052 void check_unsafe_exec(struct linux_binprm *bprm)
1054 struct task_struct *p = current;
1056 bprm->unsafe = tracehook_unsafe_exec(p);
1058 if (atomic_read(&p->fs->count) > 1 ||
1059 atomic_read(&p->files->count) > 1 ||
1060 atomic_read(&p->sighand->count) > 1)
1061 bprm->unsafe |= LSM_UNSAFE_SHARE;
1065 * Fill the binprm structure from the inode.
1066 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1068 * This may be called multiple times for binary chains (scripts for example).
1070 int prepare_binprm(struct linux_binprm *bprm)
1072 umode_t mode;
1073 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1074 int retval;
1076 mode = inode->i_mode;
1077 if (bprm->file->f_op == NULL)
1078 return -EACCES;
1080 /* clear any previous set[ug]id data from a previous binary */
1081 bprm->cred->euid = current_euid();
1082 bprm->cred->egid = current_egid();
1084 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1085 /* Set-uid? */
1086 if (mode & S_ISUID) {
1087 bprm->per_clear |= PER_CLEAR_ON_SETID;
1088 bprm->cred->euid = inode->i_uid;
1091 /* Set-gid? */
1093 * If setgid is set but no group execute bit then this
1094 * is a candidate for mandatory locking, not a setgid
1095 * executable.
1097 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1098 bprm->per_clear |= PER_CLEAR_ON_SETID;
1099 bprm->cred->egid = inode->i_gid;
1103 /* fill in binprm security blob */
1104 retval = security_bprm_set_creds(bprm);
1105 if (retval)
1106 return retval;
1107 bprm->cred_prepared = 1;
1109 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1110 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1113 EXPORT_SYMBOL(prepare_binprm);
1116 * Arguments are '\0' separated strings found at the location bprm->p
1117 * points to; chop off the first by relocating brpm->p to right after
1118 * the first '\0' encountered.
1120 int remove_arg_zero(struct linux_binprm *bprm)
1122 int ret = 0;
1123 unsigned long offset;
1124 char *kaddr;
1125 struct page *page;
1127 if (!bprm->argc)
1128 return 0;
1130 do {
1131 offset = bprm->p & ~PAGE_MASK;
1132 page = get_arg_page(bprm, bprm->p, 0);
1133 if (!page) {
1134 ret = -EFAULT;
1135 goto out;
1137 kaddr = kmap_atomic(page, KM_USER0);
1139 for (; offset < PAGE_SIZE && kaddr[offset];
1140 offset++, bprm->p++)
1143 kunmap_atomic(kaddr, KM_USER0);
1144 put_arg_page(page);
1146 if (offset == PAGE_SIZE)
1147 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1148 } while (offset == PAGE_SIZE);
1150 bprm->p++;
1151 bprm->argc--;
1152 ret = 0;
1154 out:
1155 return ret;
1157 EXPORT_SYMBOL(remove_arg_zero);
1160 * cycle the list of binary formats handler, until one recognizes the image
1162 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1164 unsigned int depth = bprm->recursion_depth;
1165 int try,retval;
1166 struct linux_binfmt *fmt;
1168 retval = security_bprm_check(bprm);
1169 if (retval)
1170 return retval;
1172 /* kernel module loader fixup */
1173 /* so we don't try to load run modprobe in kernel space. */
1174 set_fs(USER_DS);
1176 retval = audit_bprm(bprm);
1177 if (retval)
1178 return retval;
1180 retval = -ENOENT;
1181 for (try=0; try<2; try++) {
1182 read_lock(&binfmt_lock);
1183 list_for_each_entry(fmt, &formats, lh) {
1184 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1185 if (!fn)
1186 continue;
1187 if (!try_module_get(fmt->module))
1188 continue;
1189 read_unlock(&binfmt_lock);
1190 retval = fn(bprm, regs);
1192 * Restore the depth counter to its starting value
1193 * in this call, so we don't have to rely on every
1194 * load_binary function to restore it on return.
1196 bprm->recursion_depth = depth;
1197 if (retval >= 0) {
1198 if (depth == 0)
1199 tracehook_report_exec(fmt, bprm, regs);
1200 put_binfmt(fmt);
1201 allow_write_access(bprm->file);
1202 if (bprm->file)
1203 fput(bprm->file);
1204 bprm->file = NULL;
1205 current->did_exec = 1;
1206 proc_exec_connector(current);
1207 return retval;
1209 read_lock(&binfmt_lock);
1210 put_binfmt(fmt);
1211 if (retval != -ENOEXEC || bprm->mm == NULL)
1212 break;
1213 if (!bprm->file) {
1214 read_unlock(&binfmt_lock);
1215 return retval;
1218 read_unlock(&binfmt_lock);
1219 if (retval != -ENOEXEC || bprm->mm == NULL) {
1220 break;
1221 #ifdef CONFIG_MODULES
1222 } else {
1223 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1224 if (printable(bprm->buf[0]) &&
1225 printable(bprm->buf[1]) &&
1226 printable(bprm->buf[2]) &&
1227 printable(bprm->buf[3]))
1228 break; /* -ENOEXEC */
1229 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1230 #endif
1233 return retval;
1236 EXPORT_SYMBOL(search_binary_handler);
1238 void free_bprm(struct linux_binprm *bprm)
1240 free_arg_pages(bprm);
1241 if (bprm->cred)
1242 abort_creds(bprm->cred);
1243 kfree(bprm);
1247 * sys_execve() executes a new program.
1249 int do_execve(char * filename,
1250 char __user *__user *argv,
1251 char __user *__user *envp,
1252 struct pt_regs * regs)
1254 struct linux_binprm *bprm;
1255 struct file *file;
1256 struct files_struct *displaced;
1257 int retval;
1259 retval = unshare_files(&displaced);
1260 if (retval)
1261 goto out_ret;
1263 retval = -ENOMEM;
1264 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1265 if (!bprm)
1266 goto out_files;
1268 retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1269 if (retval < 0)
1270 goto out_free;
1272 retval = -ENOMEM;
1273 bprm->cred = prepare_exec_creds();
1274 if (!bprm->cred)
1275 goto out_unlock;
1276 check_unsafe_exec(bprm);
1278 file = open_exec(filename);
1279 retval = PTR_ERR(file);
1280 if (IS_ERR(file))
1281 goto out_unlock;
1283 sched_exec();
1285 bprm->file = file;
1286 bprm->filename = filename;
1287 bprm->interp = filename;
1289 retval = bprm_mm_init(bprm);
1290 if (retval)
1291 goto out_file;
1293 bprm->argc = count(argv, MAX_ARG_STRINGS);
1294 if ((retval = bprm->argc) < 0)
1295 goto out;
1297 bprm->envc = count(envp, MAX_ARG_STRINGS);
1298 if ((retval = bprm->envc) < 0)
1299 goto out;
1301 retval = prepare_binprm(bprm);
1302 if (retval < 0)
1303 goto out;
1305 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1306 if (retval < 0)
1307 goto out;
1309 bprm->exec = bprm->p;
1310 retval = copy_strings(bprm->envc, envp, bprm);
1311 if (retval < 0)
1312 goto out;
1314 retval = copy_strings(bprm->argc, argv, bprm);
1315 if (retval < 0)
1316 goto out;
1318 current->flags &= ~PF_KTHREAD;
1319 retval = search_binary_handler(bprm,regs);
1320 if (retval < 0)
1321 goto out;
1323 /* execve succeeded */
1324 mutex_unlock(&current->cred_exec_mutex);
1325 acct_update_integrals(current);
1326 free_bprm(bprm);
1327 if (displaced)
1328 put_files_struct(displaced);
1329 return retval;
1331 out:
1332 if (bprm->mm)
1333 mmput (bprm->mm);
1335 out_file:
1336 if (bprm->file) {
1337 allow_write_access(bprm->file);
1338 fput(bprm->file);
1341 out_unlock:
1342 mutex_unlock(&current->cred_exec_mutex);
1344 out_free:
1345 free_bprm(bprm);
1347 out_files:
1348 if (displaced)
1349 reset_files_struct(displaced);
1350 out_ret:
1351 return retval;
1354 int set_binfmt(struct linux_binfmt *new)
1356 struct linux_binfmt *old = current->binfmt;
1358 if (new) {
1359 if (!try_module_get(new->module))
1360 return -1;
1362 current->binfmt = new;
1363 if (old)
1364 module_put(old->module);
1365 return 0;
1368 EXPORT_SYMBOL(set_binfmt);
1370 /* format_corename will inspect the pattern parameter, and output a
1371 * name into corename, which must have space for at least
1372 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1374 static int format_corename(char *corename, long signr)
1376 const struct cred *cred = current_cred();
1377 const char *pat_ptr = core_pattern;
1378 int ispipe = (*pat_ptr == '|');
1379 char *out_ptr = corename;
1380 char *const out_end = corename + CORENAME_MAX_SIZE;
1381 int rc;
1382 int pid_in_pattern = 0;
1384 /* Repeat as long as we have more pattern to process and more output
1385 space */
1386 while (*pat_ptr) {
1387 if (*pat_ptr != '%') {
1388 if (out_ptr == out_end)
1389 goto out;
1390 *out_ptr++ = *pat_ptr++;
1391 } else {
1392 switch (*++pat_ptr) {
1393 case 0:
1394 goto out;
1395 /* Double percent, output one percent */
1396 case '%':
1397 if (out_ptr == out_end)
1398 goto out;
1399 *out_ptr++ = '%';
1400 break;
1401 /* pid */
1402 case 'p':
1403 pid_in_pattern = 1;
1404 rc = snprintf(out_ptr, out_end - out_ptr,
1405 "%d", task_tgid_vnr(current));
1406 if (rc > out_end - out_ptr)
1407 goto out;
1408 out_ptr += rc;
1409 break;
1410 /* uid */
1411 case 'u':
1412 rc = snprintf(out_ptr, out_end - out_ptr,
1413 "%d", cred->uid);
1414 if (rc > out_end - out_ptr)
1415 goto out;
1416 out_ptr += rc;
1417 break;
1418 /* gid */
1419 case 'g':
1420 rc = snprintf(out_ptr, out_end - out_ptr,
1421 "%d", cred->gid);
1422 if (rc > out_end - out_ptr)
1423 goto out;
1424 out_ptr += rc;
1425 break;
1426 /* signal that caused the coredump */
1427 case 's':
1428 rc = snprintf(out_ptr, out_end - out_ptr,
1429 "%ld", signr);
1430 if (rc > out_end - out_ptr)
1431 goto out;
1432 out_ptr += rc;
1433 break;
1434 /* UNIX time of coredump */
1435 case 't': {
1436 struct timeval tv;
1437 do_gettimeofday(&tv);
1438 rc = snprintf(out_ptr, out_end - out_ptr,
1439 "%lu", tv.tv_sec);
1440 if (rc > out_end - out_ptr)
1441 goto out;
1442 out_ptr += rc;
1443 break;
1445 /* hostname */
1446 case 'h':
1447 down_read(&uts_sem);
1448 rc = snprintf(out_ptr, out_end - out_ptr,
1449 "%s", utsname()->nodename);
1450 up_read(&uts_sem);
1451 if (rc > out_end - out_ptr)
1452 goto out;
1453 out_ptr += rc;
1454 break;
1455 /* executable */
1456 case 'e':
1457 rc = snprintf(out_ptr, out_end - out_ptr,
1458 "%s", current->comm);
1459 if (rc > out_end - out_ptr)
1460 goto out;
1461 out_ptr += rc;
1462 break;
1463 /* core limit size */
1464 case 'c':
1465 rc = snprintf(out_ptr, out_end - out_ptr,
1466 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1467 if (rc > out_end - out_ptr)
1468 goto out;
1469 out_ptr += rc;
1470 break;
1471 default:
1472 break;
1474 ++pat_ptr;
1477 /* Backward compatibility with core_uses_pid:
1479 * If core_pattern does not include a %p (as is the default)
1480 * and core_uses_pid is set, then .%pid will be appended to
1481 * the filename. Do not do this for piped commands. */
1482 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1483 rc = snprintf(out_ptr, out_end - out_ptr,
1484 ".%d", task_tgid_vnr(current));
1485 if (rc > out_end - out_ptr)
1486 goto out;
1487 out_ptr += rc;
1489 out:
1490 *out_ptr = 0;
1491 return ispipe;
1494 static int zap_process(struct task_struct *start)
1496 struct task_struct *t;
1497 int nr = 0;
1499 start->signal->flags = SIGNAL_GROUP_EXIT;
1500 start->signal->group_stop_count = 0;
1502 t = start;
1503 do {
1504 if (t != current && t->mm) {
1505 sigaddset(&t->pending.signal, SIGKILL);
1506 signal_wake_up(t, 1);
1507 nr++;
1509 } while_each_thread(start, t);
1511 return nr;
1514 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1515 struct core_state *core_state, int exit_code)
1517 struct task_struct *g, *p;
1518 unsigned long flags;
1519 int nr = -EAGAIN;
1521 spin_lock_irq(&tsk->sighand->siglock);
1522 if (!signal_group_exit(tsk->signal)) {
1523 mm->core_state = core_state;
1524 tsk->signal->group_exit_code = exit_code;
1525 nr = zap_process(tsk);
1527 spin_unlock_irq(&tsk->sighand->siglock);
1528 if (unlikely(nr < 0))
1529 return nr;
1531 if (atomic_read(&mm->mm_users) == nr + 1)
1532 goto done;
1534 * We should find and kill all tasks which use this mm, and we should
1535 * count them correctly into ->nr_threads. We don't take tasklist
1536 * lock, but this is safe wrt:
1538 * fork:
1539 * None of sub-threads can fork after zap_process(leader). All
1540 * processes which were created before this point should be
1541 * visible to zap_threads() because copy_process() adds the new
1542 * process to the tail of init_task.tasks list, and lock/unlock
1543 * of ->siglock provides a memory barrier.
1545 * do_exit:
1546 * The caller holds mm->mmap_sem. This means that the task which
1547 * uses this mm can't pass exit_mm(), so it can't exit or clear
1548 * its ->mm.
1550 * de_thread:
1551 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1552 * we must see either old or new leader, this does not matter.
1553 * However, it can change p->sighand, so lock_task_sighand(p)
1554 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1555 * it can't fail.
1557 * Note also that "g" can be the old leader with ->mm == NULL
1558 * and already unhashed and thus removed from ->thread_group.
1559 * This is OK, __unhash_process()->list_del_rcu() does not
1560 * clear the ->next pointer, we will find the new leader via
1561 * next_thread().
1563 rcu_read_lock();
1564 for_each_process(g) {
1565 if (g == tsk->group_leader)
1566 continue;
1567 if (g->flags & PF_KTHREAD)
1568 continue;
1569 p = g;
1570 do {
1571 if (p->mm) {
1572 if (unlikely(p->mm == mm)) {
1573 lock_task_sighand(p, &flags);
1574 nr += zap_process(p);
1575 unlock_task_sighand(p, &flags);
1577 break;
1579 } while_each_thread(g, p);
1581 rcu_read_unlock();
1582 done:
1583 atomic_set(&core_state->nr_threads, nr);
1584 return nr;
1587 static int coredump_wait(int exit_code, struct core_state *core_state)
1589 struct task_struct *tsk = current;
1590 struct mm_struct *mm = tsk->mm;
1591 struct completion *vfork_done;
1592 int core_waiters;
1594 init_completion(&core_state->startup);
1595 core_state->dumper.task = tsk;
1596 core_state->dumper.next = NULL;
1597 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1598 up_write(&mm->mmap_sem);
1600 if (unlikely(core_waiters < 0))
1601 goto fail;
1604 * Make sure nobody is waiting for us to release the VM,
1605 * otherwise we can deadlock when we wait on each other
1607 vfork_done = tsk->vfork_done;
1608 if (vfork_done) {
1609 tsk->vfork_done = NULL;
1610 complete(vfork_done);
1613 if (core_waiters)
1614 wait_for_completion(&core_state->startup);
1615 fail:
1616 return core_waiters;
1619 static void coredump_finish(struct mm_struct *mm)
1621 struct core_thread *curr, *next;
1622 struct task_struct *task;
1624 next = mm->core_state->dumper.next;
1625 while ((curr = next) != NULL) {
1626 next = curr->next;
1627 task = curr->task;
1629 * see exit_mm(), curr->task must not see
1630 * ->task == NULL before we read ->next.
1632 smp_mb();
1633 curr->task = NULL;
1634 wake_up_process(task);
1637 mm->core_state = NULL;
1641 * set_dumpable converts traditional three-value dumpable to two flags and
1642 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1643 * these bits are not changed atomically. So get_dumpable can observe the
1644 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1645 * return either old dumpable or new one by paying attention to the order of
1646 * modifying the bits.
1648 * dumpable | mm->flags (binary)
1649 * old new | initial interim final
1650 * ---------+-----------------------
1651 * 0 1 | 00 01 01
1652 * 0 2 | 00 10(*) 11
1653 * 1 0 | 01 00 00
1654 * 1 2 | 01 11 11
1655 * 2 0 | 11 10(*) 00
1656 * 2 1 | 11 11 01
1658 * (*) get_dumpable regards interim value of 10 as 11.
1660 void set_dumpable(struct mm_struct *mm, int value)
1662 switch (value) {
1663 case 0:
1664 clear_bit(MMF_DUMPABLE, &mm->flags);
1665 smp_wmb();
1666 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1667 break;
1668 case 1:
1669 set_bit(MMF_DUMPABLE, &mm->flags);
1670 smp_wmb();
1671 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1672 break;
1673 case 2:
1674 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1675 smp_wmb();
1676 set_bit(MMF_DUMPABLE, &mm->flags);
1677 break;
1681 int get_dumpable(struct mm_struct *mm)
1683 int ret;
1685 ret = mm->flags & 0x3;
1686 return (ret >= 2) ? 2 : ret;
1689 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1691 struct core_state core_state;
1692 char corename[CORENAME_MAX_SIZE + 1];
1693 struct mm_struct *mm = current->mm;
1694 struct linux_binfmt * binfmt;
1695 struct inode * inode;
1696 struct file * file;
1697 const struct cred *old_cred;
1698 struct cred *cred;
1699 int retval = 0;
1700 int flag = 0;
1701 int ispipe = 0;
1702 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1703 char **helper_argv = NULL;
1704 int helper_argc = 0;
1705 char *delimit;
1707 audit_core_dumps(signr);
1709 binfmt = current->binfmt;
1710 if (!binfmt || !binfmt->core_dump)
1711 goto fail;
1713 cred = prepare_creds();
1714 if (!cred) {
1715 retval = -ENOMEM;
1716 goto fail;
1719 down_write(&mm->mmap_sem);
1721 * If another thread got here first, or we are not dumpable, bail out.
1723 if (mm->core_state || !get_dumpable(mm)) {
1724 up_write(&mm->mmap_sem);
1725 put_cred(cred);
1726 goto fail;
1730 * We cannot trust fsuid as being the "true" uid of the
1731 * process nor do we know its entire history. We only know it
1732 * was tainted so we dump it as root in mode 2.
1734 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1735 flag = O_EXCL; /* Stop rewrite attacks */
1736 cred->fsuid = 0; /* Dump root private */
1739 retval = coredump_wait(exit_code, &core_state);
1740 if (retval < 0) {
1741 put_cred(cred);
1742 goto fail;
1745 old_cred = override_creds(cred);
1748 * Clear any false indication of pending signals that might
1749 * be seen by the filesystem code called to write the core file.
1751 clear_thread_flag(TIF_SIGPENDING);
1754 * lock_kernel() because format_corename() is controlled by sysctl, which
1755 * uses lock_kernel()
1757 lock_kernel();
1758 ispipe = format_corename(corename, signr);
1759 unlock_kernel();
1761 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1762 * to a pipe. Since we're not writing directly to the filesystem
1763 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1764 * created unless the pipe reader choses to write out the core file
1765 * at which point file size limits and permissions will be imposed
1766 * as it does with any other process
1768 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1769 goto fail_unlock;
1771 if (ispipe) {
1772 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1773 if (!helper_argv) {
1774 printk(KERN_WARNING "%s failed to allocate memory\n",
1775 __func__);
1776 goto fail_unlock;
1778 /* Terminate the string before the first option */
1779 delimit = strchr(corename, ' ');
1780 if (delimit)
1781 *delimit = '\0';
1782 delimit = strrchr(helper_argv[0], '/');
1783 if (delimit)
1784 delimit++;
1785 else
1786 delimit = helper_argv[0];
1787 if (!strcmp(delimit, current->comm)) {
1788 printk(KERN_NOTICE "Recursive core dump detected, "
1789 "aborting\n");
1790 goto fail_unlock;
1793 core_limit = RLIM_INFINITY;
1795 /* SIGPIPE can happen, but it's just never processed */
1796 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1797 &file)) {
1798 printk(KERN_INFO "Core dump to %s pipe failed\n",
1799 corename);
1800 goto fail_unlock;
1802 } else
1803 file = filp_open(corename,
1804 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1805 0600);
1806 if (IS_ERR(file))
1807 goto fail_unlock;
1808 inode = file->f_path.dentry->d_inode;
1809 if (inode->i_nlink > 1)
1810 goto close_fail; /* multiple links - don't dump */
1811 if (!ispipe && d_unhashed(file->f_path.dentry))
1812 goto close_fail;
1814 /* AK: actually i see no reason to not allow this for named pipes etc.,
1815 but keep the previous behaviour for now. */
1816 if (!ispipe && !S_ISREG(inode->i_mode))
1817 goto close_fail;
1819 * Dont allow local users get cute and trick others to coredump
1820 * into their pre-created files:
1822 if (inode->i_uid != current_fsuid())
1823 goto close_fail;
1824 if (!file->f_op)
1825 goto close_fail;
1826 if (!file->f_op->write)
1827 goto close_fail;
1828 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1829 goto close_fail;
1831 retval = binfmt->core_dump(signr, regs, file, core_limit);
1833 if (retval)
1834 current->signal->group_exit_code |= 0x80;
1835 close_fail:
1836 filp_close(file, NULL);
1837 fail_unlock:
1838 if (helper_argv)
1839 argv_free(helper_argv);
1841 revert_creds(old_cred);
1842 put_cred(cred);
1843 coredump_finish(mm);
1844 fail:
1845 return;