ACPI: Introduce acpi_get_pci_dev()
[linux-2.6/linux-acpi-2.6.git] / fs / exec.c
blob895823d0149d9cfbd75bb34b670662dafb7f9ef6
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/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 #include <linux/fs_struct.h>
58 #include <asm/uaccess.h>
59 #include <asm/mmu_context.h>
60 #include <asm/tlb.h>
61 #include "internal.h"
63 int core_uses_pid;
64 char core_pattern[CORENAME_MAX_SIZE] = "core";
65 int suid_dumpable = 0;
67 /* The maximal length of core_pattern is also specified in sysctl.c */
69 static LIST_HEAD(formats);
70 static DEFINE_RWLOCK(binfmt_lock);
72 int __register_binfmt(struct linux_binfmt * fmt, int insert)
74 if (!fmt)
75 return -EINVAL;
76 write_lock(&binfmt_lock);
77 insert ? list_add(&fmt->lh, &formats) :
78 list_add_tail(&fmt->lh, &formats);
79 write_unlock(&binfmt_lock);
80 return 0;
83 EXPORT_SYMBOL(__register_binfmt);
85 void unregister_binfmt(struct linux_binfmt * fmt)
87 write_lock(&binfmt_lock);
88 list_del(&fmt->lh);
89 write_unlock(&binfmt_lock);
92 EXPORT_SYMBOL(unregister_binfmt);
94 static inline void put_binfmt(struct linux_binfmt * fmt)
96 module_put(fmt->module);
100 * Note that a shared library must be both readable and executable due to
101 * security reasons.
103 * Also note that we take the address to load from from the file itself.
105 SYSCALL_DEFINE1(uselib, const char __user *, library)
107 struct file *file;
108 char *tmp = getname(library);
109 int error = PTR_ERR(tmp);
111 if (IS_ERR(tmp))
112 goto out;
114 file = do_filp_open(AT_FDCWD, tmp,
115 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
116 MAY_READ | MAY_EXEC | MAY_OPEN);
117 putname(tmp);
118 error = PTR_ERR(file);
119 if (IS_ERR(file))
120 goto out;
122 error = -EINVAL;
123 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
124 goto exit;
126 error = -EACCES;
127 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
128 goto exit;
130 fsnotify_open(file->f_path.dentry);
132 error = -ENOEXEC;
133 if(file->f_op) {
134 struct linux_binfmt * fmt;
136 read_lock(&binfmt_lock);
137 list_for_each_entry(fmt, &formats, lh) {
138 if (!fmt->load_shlib)
139 continue;
140 if (!try_module_get(fmt->module))
141 continue;
142 read_unlock(&binfmt_lock);
143 error = fmt->load_shlib(file);
144 read_lock(&binfmt_lock);
145 put_binfmt(fmt);
146 if (error != -ENOEXEC)
147 break;
149 read_unlock(&binfmt_lock);
151 exit:
152 fput(file);
153 out:
154 return error;
157 #ifdef CONFIG_MMU
159 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
160 int write)
162 struct page *page;
163 int ret;
165 #ifdef CONFIG_STACK_GROWSUP
166 if (write) {
167 ret = expand_stack_downwards(bprm->vma, pos);
168 if (ret < 0)
169 return NULL;
171 #endif
172 ret = get_user_pages(current, bprm->mm, pos,
173 1, write, 1, &page, NULL);
174 if (ret <= 0)
175 return NULL;
177 if (write) {
178 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
179 struct rlimit *rlim;
182 * We've historically supported up to 32 pages (ARG_MAX)
183 * of argument strings even with small stacks
185 if (size <= ARG_MAX)
186 return page;
189 * Limit to 1/4-th the stack size for the argv+env strings.
190 * This ensures that:
191 * - the remaining binfmt code will not run out of stack space,
192 * - the program will have a reasonable amount of stack left
193 * to work from.
195 rlim = current->signal->rlim;
196 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
197 put_page(page);
198 return NULL;
202 return page;
205 static void put_arg_page(struct page *page)
207 put_page(page);
210 static void free_arg_page(struct linux_binprm *bprm, int i)
214 static void free_arg_pages(struct linux_binprm *bprm)
218 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
219 struct page *page)
221 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
224 static int __bprm_mm_init(struct linux_binprm *bprm)
226 int err;
227 struct vm_area_struct *vma = NULL;
228 struct mm_struct *mm = bprm->mm;
230 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
231 if (!vma)
232 return -ENOMEM;
234 down_write(&mm->mmap_sem);
235 vma->vm_mm = mm;
238 * Place the stack at the largest stack address the architecture
239 * supports. Later, we'll move this to an appropriate place. We don't
240 * use STACK_TOP because that can depend on attributes which aren't
241 * configured yet.
243 vma->vm_end = STACK_TOP_MAX;
244 vma->vm_start = vma->vm_end - PAGE_SIZE;
245 vma->vm_flags = VM_STACK_FLAGS;
246 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
247 err = insert_vm_struct(mm, vma);
248 if (err)
249 goto err;
251 mm->stack_vm = mm->total_vm = 1;
252 up_write(&mm->mmap_sem);
253 bprm->p = vma->vm_end - sizeof(void *);
254 return 0;
255 err:
256 up_write(&mm->mmap_sem);
257 bprm->vma = NULL;
258 kmem_cache_free(vm_area_cachep, vma);
259 return err;
262 static bool valid_arg_len(struct linux_binprm *bprm, long len)
264 return len <= MAX_ARG_STRLEN;
267 #else
269 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
270 int write)
272 struct page *page;
274 page = bprm->page[pos / PAGE_SIZE];
275 if (!page && write) {
276 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
277 if (!page)
278 return NULL;
279 bprm->page[pos / PAGE_SIZE] = page;
282 return page;
285 static void put_arg_page(struct page *page)
289 static void free_arg_page(struct linux_binprm *bprm, int i)
291 if (bprm->page[i]) {
292 __free_page(bprm->page[i]);
293 bprm->page[i] = NULL;
297 static void free_arg_pages(struct linux_binprm *bprm)
299 int i;
301 for (i = 0; i < MAX_ARG_PAGES; i++)
302 free_arg_page(bprm, i);
305 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
306 struct page *page)
310 static int __bprm_mm_init(struct linux_binprm *bprm)
312 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
313 return 0;
316 static bool valid_arg_len(struct linux_binprm *bprm, long len)
318 return len <= bprm->p;
321 #endif /* CONFIG_MMU */
324 * Create a new mm_struct and populate it with a temporary stack
325 * vm_area_struct. We don't have enough context at this point to set the stack
326 * flags, permissions, and offset, so we use temporary values. We'll update
327 * them later in setup_arg_pages().
329 int bprm_mm_init(struct linux_binprm *bprm)
331 int err;
332 struct mm_struct *mm = NULL;
334 bprm->mm = mm = mm_alloc();
335 err = -ENOMEM;
336 if (!mm)
337 goto err;
339 err = init_new_context(current, mm);
340 if (err)
341 goto err;
343 err = __bprm_mm_init(bprm);
344 if (err)
345 goto err;
347 return 0;
349 err:
350 if (mm) {
351 bprm->mm = NULL;
352 mmdrop(mm);
355 return err;
359 * count() counts the number of strings in array ARGV.
361 static int count(char __user * __user * argv, int max)
363 int i = 0;
365 if (argv != NULL) {
366 for (;;) {
367 char __user * p;
369 if (get_user(p, argv))
370 return -EFAULT;
371 if (!p)
372 break;
373 argv++;
374 if (i++ >= max)
375 return -E2BIG;
376 cond_resched();
379 return i;
383 * 'copy_strings()' copies argument/environment strings from the old
384 * processes's memory to the new process's stack. The call to get_user_pages()
385 * ensures the destination page is created and not swapped out.
387 static int copy_strings(int argc, char __user * __user * argv,
388 struct linux_binprm *bprm)
390 struct page *kmapped_page = NULL;
391 char *kaddr = NULL;
392 unsigned long kpos = 0;
393 int ret;
395 while (argc-- > 0) {
396 char __user *str;
397 int len;
398 unsigned long pos;
400 if (get_user(str, argv+argc) ||
401 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
402 ret = -EFAULT;
403 goto out;
406 if (!valid_arg_len(bprm, len)) {
407 ret = -E2BIG;
408 goto out;
411 /* We're going to work our way backwords. */
412 pos = bprm->p;
413 str += len;
414 bprm->p -= len;
416 while (len > 0) {
417 int offset, bytes_to_copy;
419 offset = pos % PAGE_SIZE;
420 if (offset == 0)
421 offset = PAGE_SIZE;
423 bytes_to_copy = offset;
424 if (bytes_to_copy > len)
425 bytes_to_copy = len;
427 offset -= bytes_to_copy;
428 pos -= bytes_to_copy;
429 str -= bytes_to_copy;
430 len -= bytes_to_copy;
432 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
433 struct page *page;
435 page = get_arg_page(bprm, pos, 1);
436 if (!page) {
437 ret = -E2BIG;
438 goto out;
441 if (kmapped_page) {
442 flush_kernel_dcache_page(kmapped_page);
443 kunmap(kmapped_page);
444 put_arg_page(kmapped_page);
446 kmapped_page = page;
447 kaddr = kmap(kmapped_page);
448 kpos = pos & PAGE_MASK;
449 flush_arg_page(bprm, kpos, kmapped_page);
451 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
452 ret = -EFAULT;
453 goto out;
457 ret = 0;
458 out:
459 if (kmapped_page) {
460 flush_kernel_dcache_page(kmapped_page);
461 kunmap(kmapped_page);
462 put_arg_page(kmapped_page);
464 return ret;
468 * Like copy_strings, but get argv and its values from kernel memory.
470 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
472 int r;
473 mm_segment_t oldfs = get_fs();
474 set_fs(KERNEL_DS);
475 r = copy_strings(argc, (char __user * __user *)argv, bprm);
476 set_fs(oldfs);
477 return r;
479 EXPORT_SYMBOL(copy_strings_kernel);
481 #ifdef CONFIG_MMU
484 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
485 * the binfmt code determines where the new stack should reside, we shift it to
486 * its final location. The process proceeds as follows:
488 * 1) Use shift to calculate the new vma endpoints.
489 * 2) Extend vma to cover both the old and new ranges. This ensures the
490 * arguments passed to subsequent functions are consistent.
491 * 3) Move vma's page tables to the new range.
492 * 4) Free up any cleared pgd range.
493 * 5) Shrink the vma to cover only the new range.
495 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
497 struct mm_struct *mm = vma->vm_mm;
498 unsigned long old_start = vma->vm_start;
499 unsigned long old_end = vma->vm_end;
500 unsigned long length = old_end - old_start;
501 unsigned long new_start = old_start - shift;
502 unsigned long new_end = old_end - shift;
503 struct mmu_gather *tlb;
505 BUG_ON(new_start > new_end);
508 * ensure there are no vmas between where we want to go
509 * and where we are
511 if (vma != find_vma(mm, new_start))
512 return -EFAULT;
515 * cover the whole range: [new_start, old_end)
517 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
520 * move the page tables downwards, on failure we rely on
521 * process cleanup to remove whatever mess we made.
523 if (length != move_page_tables(vma, old_start,
524 vma, new_start, length))
525 return -ENOMEM;
527 lru_add_drain();
528 tlb = tlb_gather_mmu(mm, 0);
529 if (new_end > old_start) {
531 * when the old and new regions overlap clear from new_end.
533 free_pgd_range(tlb, new_end, old_end, new_end,
534 vma->vm_next ? vma->vm_next->vm_start : 0);
535 } else {
537 * otherwise, clean from old_start; this is done to not touch
538 * the address space in [new_end, old_start) some architectures
539 * have constraints on va-space that make this illegal (IA64) -
540 * for the others its just a little faster.
542 free_pgd_range(tlb, old_start, old_end, new_end,
543 vma->vm_next ? vma->vm_next->vm_start : 0);
545 tlb_finish_mmu(tlb, new_end, old_end);
548 * shrink the vma to just the new range.
550 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
552 return 0;
555 #define EXTRA_STACK_VM_PAGES 20 /* random */
558 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
559 * the stack is optionally relocated, and some extra space is added.
561 int setup_arg_pages(struct linux_binprm *bprm,
562 unsigned long stack_top,
563 int executable_stack)
565 unsigned long ret;
566 unsigned long stack_shift;
567 struct mm_struct *mm = current->mm;
568 struct vm_area_struct *vma = bprm->vma;
569 struct vm_area_struct *prev = NULL;
570 unsigned long vm_flags;
571 unsigned long stack_base;
573 #ifdef CONFIG_STACK_GROWSUP
574 /* Limit stack size to 1GB */
575 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
576 if (stack_base > (1 << 30))
577 stack_base = 1 << 30;
579 /* Make sure we didn't let the argument array grow too large. */
580 if (vma->vm_end - vma->vm_start > stack_base)
581 return -ENOMEM;
583 stack_base = PAGE_ALIGN(stack_top - stack_base);
585 stack_shift = vma->vm_start - stack_base;
586 mm->arg_start = bprm->p - stack_shift;
587 bprm->p = vma->vm_end - stack_shift;
588 #else
589 stack_top = arch_align_stack(stack_top);
590 stack_top = PAGE_ALIGN(stack_top);
591 stack_shift = vma->vm_end - stack_top;
593 bprm->p -= stack_shift;
594 mm->arg_start = bprm->p;
595 #endif
597 if (bprm->loader)
598 bprm->loader -= stack_shift;
599 bprm->exec -= stack_shift;
601 down_write(&mm->mmap_sem);
602 vm_flags = VM_STACK_FLAGS;
605 * Adjust stack execute permissions; explicitly enable for
606 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
607 * (arch default) otherwise.
609 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
610 vm_flags |= VM_EXEC;
611 else if (executable_stack == EXSTACK_DISABLE_X)
612 vm_flags &= ~VM_EXEC;
613 vm_flags |= mm->def_flags;
615 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
616 vm_flags);
617 if (ret)
618 goto out_unlock;
619 BUG_ON(prev != vma);
621 /* Move stack pages down in memory. */
622 if (stack_shift) {
623 ret = shift_arg_pages(vma, stack_shift);
624 if (ret) {
625 up_write(&mm->mmap_sem);
626 return ret;
630 #ifdef CONFIG_STACK_GROWSUP
631 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
632 #else
633 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
634 #endif
635 ret = expand_stack(vma, stack_base);
636 if (ret)
637 ret = -EFAULT;
639 out_unlock:
640 up_write(&mm->mmap_sem);
641 return 0;
643 EXPORT_SYMBOL(setup_arg_pages);
645 #endif /* CONFIG_MMU */
647 struct file *open_exec(const char *name)
649 struct file *file;
650 int err;
652 file = do_filp_open(AT_FDCWD, name,
653 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
654 MAY_EXEC | MAY_OPEN);
655 if (IS_ERR(file))
656 goto out;
658 err = -EACCES;
659 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
660 goto exit;
662 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
663 goto exit;
665 fsnotify_open(file->f_path.dentry);
667 err = deny_write_access(file);
668 if (err)
669 goto exit;
671 out:
672 return file;
674 exit:
675 fput(file);
676 return ERR_PTR(err);
678 EXPORT_SYMBOL(open_exec);
680 int kernel_read(struct file *file, unsigned long offset,
681 char *addr, unsigned long count)
683 mm_segment_t old_fs;
684 loff_t pos = offset;
685 int result;
687 old_fs = get_fs();
688 set_fs(get_ds());
689 /* The cast to a user pointer is valid due to the set_fs() */
690 result = vfs_read(file, (void __user *)addr, count, &pos);
691 set_fs(old_fs);
692 return result;
695 EXPORT_SYMBOL(kernel_read);
697 static int exec_mmap(struct mm_struct *mm)
699 struct task_struct *tsk;
700 struct mm_struct * old_mm, *active_mm;
702 /* Notify parent that we're no longer interested in the old VM */
703 tsk = current;
704 old_mm = current->mm;
705 mm_release(tsk, old_mm);
707 if (old_mm) {
709 * Make sure that if there is a core dump in progress
710 * for the old mm, we get out and die instead of going
711 * through with the exec. We must hold mmap_sem around
712 * checking core_state and changing tsk->mm.
714 down_read(&old_mm->mmap_sem);
715 if (unlikely(old_mm->core_state)) {
716 up_read(&old_mm->mmap_sem);
717 return -EINTR;
720 task_lock(tsk);
721 active_mm = tsk->active_mm;
722 tsk->mm = mm;
723 tsk->active_mm = mm;
724 activate_mm(active_mm, mm);
725 task_unlock(tsk);
726 arch_pick_mmap_layout(mm);
727 if (old_mm) {
728 up_read(&old_mm->mmap_sem);
729 BUG_ON(active_mm != old_mm);
730 mm_update_next_owner(old_mm);
731 mmput(old_mm);
732 return 0;
734 mmdrop(active_mm);
735 return 0;
739 * This function makes sure the current process has its own signal table,
740 * so that flush_signal_handlers can later reset the handlers without
741 * disturbing other processes. (Other processes might share the signal
742 * table via the CLONE_SIGHAND option to clone().)
744 static int de_thread(struct task_struct *tsk)
746 struct signal_struct *sig = tsk->signal;
747 struct sighand_struct *oldsighand = tsk->sighand;
748 spinlock_t *lock = &oldsighand->siglock;
749 int count;
751 if (thread_group_empty(tsk))
752 goto no_thread_group;
755 * Kill all other threads in the thread group.
757 spin_lock_irq(lock);
758 if (signal_group_exit(sig)) {
760 * Another group action in progress, just
761 * return so that the signal is processed.
763 spin_unlock_irq(lock);
764 return -EAGAIN;
766 sig->group_exit_task = tsk;
767 zap_other_threads(tsk);
769 /* Account for the thread group leader hanging around: */
770 count = thread_group_leader(tsk) ? 1 : 2;
771 sig->notify_count = count;
772 while (atomic_read(&sig->count) > count) {
773 __set_current_state(TASK_UNINTERRUPTIBLE);
774 spin_unlock_irq(lock);
775 schedule();
776 spin_lock_irq(lock);
778 spin_unlock_irq(lock);
781 * At this point all other threads have exited, all we have to
782 * do is to wait for the thread group leader to become inactive,
783 * and to assume its PID:
785 if (!thread_group_leader(tsk)) {
786 struct task_struct *leader = tsk->group_leader;
788 sig->notify_count = -1; /* for exit_notify() */
789 for (;;) {
790 write_lock_irq(&tasklist_lock);
791 if (likely(leader->exit_state))
792 break;
793 __set_current_state(TASK_UNINTERRUPTIBLE);
794 write_unlock_irq(&tasklist_lock);
795 schedule();
799 * The only record we have of the real-time age of a
800 * process, regardless of execs it's done, is start_time.
801 * All the past CPU time is accumulated in signal_struct
802 * from sister threads now dead. But in this non-leader
803 * exec, nothing survives from the original leader thread,
804 * whose birth marks the true age of this process now.
805 * When we take on its identity by switching to its PID, we
806 * also take its birthdate (always earlier than our own).
808 tsk->start_time = leader->start_time;
810 BUG_ON(!same_thread_group(leader, tsk));
811 BUG_ON(has_group_leader_pid(tsk));
813 * An exec() starts a new thread group with the
814 * TGID of the previous thread group. Rehash the
815 * two threads with a switched PID, and release
816 * the former thread group leader:
819 /* Become a process group leader with the old leader's pid.
820 * The old leader becomes a thread of the this thread group.
821 * Note: The old leader also uses this pid until release_task
822 * is called. Odd but simple and correct.
824 detach_pid(tsk, PIDTYPE_PID);
825 tsk->pid = leader->pid;
826 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
827 transfer_pid(leader, tsk, PIDTYPE_PGID);
828 transfer_pid(leader, tsk, PIDTYPE_SID);
829 list_replace_rcu(&leader->tasks, &tsk->tasks);
831 tsk->group_leader = tsk;
832 leader->group_leader = tsk;
834 tsk->exit_signal = SIGCHLD;
836 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
837 leader->exit_state = EXIT_DEAD;
838 write_unlock_irq(&tasklist_lock);
840 release_task(leader);
843 sig->group_exit_task = NULL;
844 sig->notify_count = 0;
846 no_thread_group:
847 exit_itimers(sig);
848 flush_itimer_signals();
850 if (atomic_read(&oldsighand->count) != 1) {
851 struct sighand_struct *newsighand;
853 * This ->sighand is shared with the CLONE_SIGHAND
854 * but not CLONE_THREAD task, switch to the new one.
856 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
857 if (!newsighand)
858 return -ENOMEM;
860 atomic_set(&newsighand->count, 1);
861 memcpy(newsighand->action, oldsighand->action,
862 sizeof(newsighand->action));
864 write_lock_irq(&tasklist_lock);
865 spin_lock(&oldsighand->siglock);
866 rcu_assign_pointer(tsk->sighand, newsighand);
867 spin_unlock(&oldsighand->siglock);
868 write_unlock_irq(&tasklist_lock);
870 __cleanup_sighand(oldsighand);
873 BUG_ON(!thread_group_leader(tsk));
874 return 0;
878 * These functions flushes out all traces of the currently running executable
879 * so that a new one can be started
881 static void flush_old_files(struct files_struct * files)
883 long j = -1;
884 struct fdtable *fdt;
886 spin_lock(&files->file_lock);
887 for (;;) {
888 unsigned long set, i;
890 j++;
891 i = j * __NFDBITS;
892 fdt = files_fdtable(files);
893 if (i >= fdt->max_fds)
894 break;
895 set = fdt->close_on_exec->fds_bits[j];
896 if (!set)
897 continue;
898 fdt->close_on_exec->fds_bits[j] = 0;
899 spin_unlock(&files->file_lock);
900 for ( ; set ; i++,set >>= 1) {
901 if (set & 1) {
902 sys_close(i);
905 spin_lock(&files->file_lock);
908 spin_unlock(&files->file_lock);
911 char *get_task_comm(char *buf, struct task_struct *tsk)
913 /* buf must be at least sizeof(tsk->comm) in size */
914 task_lock(tsk);
915 strncpy(buf, tsk->comm, sizeof(tsk->comm));
916 task_unlock(tsk);
917 return buf;
920 void set_task_comm(struct task_struct *tsk, char *buf)
922 task_lock(tsk);
923 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
924 task_unlock(tsk);
927 int flush_old_exec(struct linux_binprm * bprm)
929 char * name;
930 int i, ch, retval;
931 char tcomm[sizeof(current->comm)];
934 * Make sure we have a private signal table and that
935 * we are unassociated from the previous thread group.
937 retval = de_thread(current);
938 if (retval)
939 goto out;
941 set_mm_exe_file(bprm->mm, bprm->file);
944 * Release all of the old mmap stuff
946 retval = exec_mmap(bprm->mm);
947 if (retval)
948 goto out;
950 bprm->mm = NULL; /* We're using it now */
952 /* This is the point of no return */
953 current->sas_ss_sp = current->sas_ss_size = 0;
955 if (current_euid() == current_uid() && current_egid() == current_gid())
956 set_dumpable(current->mm, 1);
957 else
958 set_dumpable(current->mm, suid_dumpable);
960 name = bprm->filename;
962 /* Copies the binary name from after last slash */
963 for (i=0; (ch = *(name++)) != '\0';) {
964 if (ch == '/')
965 i = 0; /* overwrite what we wrote */
966 else
967 if (i < (sizeof(tcomm) - 1))
968 tcomm[i++] = ch;
970 tcomm[i] = '\0';
971 set_task_comm(current, tcomm);
973 current->flags &= ~PF_RANDOMIZE;
974 flush_thread();
976 /* Set the new mm task size. We have to do that late because it may
977 * depend on TIF_32BIT which is only updated in flush_thread() on
978 * some architectures like powerpc
980 current->mm->task_size = TASK_SIZE;
982 /* install the new credentials */
983 if (bprm->cred->uid != current_euid() ||
984 bprm->cred->gid != current_egid()) {
985 current->pdeath_signal = 0;
986 } else if (file_permission(bprm->file, MAY_READ) ||
987 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
988 set_dumpable(current->mm, suid_dumpable);
991 current->personality &= ~bprm->per_clear;
993 /* An exec changes our domain. We are no longer part of the thread
994 group */
996 current->self_exec_id++;
998 flush_signal_handlers(current, 0);
999 flush_old_files(current->files);
1001 return 0;
1003 out:
1004 return retval;
1007 EXPORT_SYMBOL(flush_old_exec);
1010 * install the new credentials for this executable
1012 void install_exec_creds(struct linux_binprm *bprm)
1014 security_bprm_committing_creds(bprm);
1016 commit_creds(bprm->cred);
1017 bprm->cred = NULL;
1019 /* cred_exec_mutex must be held at least to this point to prevent
1020 * ptrace_attach() from altering our determination of the task's
1021 * credentials; any time after this it may be unlocked */
1023 security_bprm_committed_creds(bprm);
1025 EXPORT_SYMBOL(install_exec_creds);
1028 * determine how safe it is to execute the proposed program
1029 * - the caller must hold current->cred_exec_mutex to protect against
1030 * PTRACE_ATTACH
1032 int check_unsafe_exec(struct linux_binprm *bprm)
1034 struct task_struct *p = current, *t;
1035 unsigned n_fs;
1036 int res = 0;
1038 bprm->unsafe = tracehook_unsafe_exec(p);
1040 n_fs = 1;
1041 write_lock(&p->fs->lock);
1042 rcu_read_lock();
1043 for (t = next_thread(p); t != p; t = next_thread(t)) {
1044 if (t->fs == p->fs)
1045 n_fs++;
1047 rcu_read_unlock();
1049 if (p->fs->users > n_fs) {
1050 bprm->unsafe |= LSM_UNSAFE_SHARE;
1051 } else {
1052 res = -EAGAIN;
1053 if (!p->fs->in_exec) {
1054 p->fs->in_exec = 1;
1055 res = 1;
1058 write_unlock(&p->fs->lock);
1060 return res;
1064 * Fill the binprm structure from the inode.
1065 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1067 * This may be called multiple times for binary chains (scripts for example).
1069 int prepare_binprm(struct linux_binprm *bprm)
1071 umode_t mode;
1072 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1073 int retval;
1075 mode = inode->i_mode;
1076 if (bprm->file->f_op == NULL)
1077 return -EACCES;
1079 /* clear any previous set[ug]id data from a previous binary */
1080 bprm->cred->euid = current_euid();
1081 bprm->cred->egid = current_egid();
1083 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1084 /* Set-uid? */
1085 if (mode & S_ISUID) {
1086 bprm->per_clear |= PER_CLEAR_ON_SETID;
1087 bprm->cred->euid = inode->i_uid;
1090 /* Set-gid? */
1092 * If setgid is set but no group execute bit then this
1093 * is a candidate for mandatory locking, not a setgid
1094 * executable.
1096 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1097 bprm->per_clear |= PER_CLEAR_ON_SETID;
1098 bprm->cred->egid = inode->i_gid;
1102 /* fill in binprm security blob */
1103 retval = security_bprm_set_creds(bprm);
1104 if (retval)
1105 return retval;
1106 bprm->cred_prepared = 1;
1108 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1109 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1112 EXPORT_SYMBOL(prepare_binprm);
1115 * Arguments are '\0' separated strings found at the location bprm->p
1116 * points to; chop off the first by relocating brpm->p to right after
1117 * the first '\0' encountered.
1119 int remove_arg_zero(struct linux_binprm *bprm)
1121 int ret = 0;
1122 unsigned long offset;
1123 char *kaddr;
1124 struct page *page;
1126 if (!bprm->argc)
1127 return 0;
1129 do {
1130 offset = bprm->p & ~PAGE_MASK;
1131 page = get_arg_page(bprm, bprm->p, 0);
1132 if (!page) {
1133 ret = -EFAULT;
1134 goto out;
1136 kaddr = kmap_atomic(page, KM_USER0);
1138 for (; offset < PAGE_SIZE && kaddr[offset];
1139 offset++, bprm->p++)
1142 kunmap_atomic(kaddr, KM_USER0);
1143 put_arg_page(page);
1145 if (offset == PAGE_SIZE)
1146 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1147 } while (offset == PAGE_SIZE);
1149 bprm->p++;
1150 bprm->argc--;
1151 ret = 0;
1153 out:
1154 return ret;
1156 EXPORT_SYMBOL(remove_arg_zero);
1159 * cycle the list of binary formats handler, until one recognizes the image
1161 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1163 unsigned int depth = bprm->recursion_depth;
1164 int try,retval;
1165 struct linux_binfmt *fmt;
1167 retval = security_bprm_check(bprm);
1168 if (retval)
1169 return retval;
1170 retval = ima_bprm_check(bprm);
1171 if (retval)
1172 return retval;
1174 /* kernel module loader fixup */
1175 /* so we don't try to load run modprobe in kernel space. */
1176 set_fs(USER_DS);
1178 retval = audit_bprm(bprm);
1179 if (retval)
1180 return retval;
1182 retval = -ENOENT;
1183 for (try=0; try<2; try++) {
1184 read_lock(&binfmt_lock);
1185 list_for_each_entry(fmt, &formats, lh) {
1186 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1187 if (!fn)
1188 continue;
1189 if (!try_module_get(fmt->module))
1190 continue;
1191 read_unlock(&binfmt_lock);
1192 retval = fn(bprm, regs);
1194 * Restore the depth counter to its starting value
1195 * in this call, so we don't have to rely on every
1196 * load_binary function to restore it on return.
1198 bprm->recursion_depth = depth;
1199 if (retval >= 0) {
1200 if (depth == 0)
1201 tracehook_report_exec(fmt, bprm, regs);
1202 put_binfmt(fmt);
1203 allow_write_access(bprm->file);
1204 if (bprm->file)
1205 fput(bprm->file);
1206 bprm->file = NULL;
1207 current->did_exec = 1;
1208 proc_exec_connector(current);
1209 return retval;
1211 read_lock(&binfmt_lock);
1212 put_binfmt(fmt);
1213 if (retval != -ENOEXEC || bprm->mm == NULL)
1214 break;
1215 if (!bprm->file) {
1216 read_unlock(&binfmt_lock);
1217 return retval;
1220 read_unlock(&binfmt_lock);
1221 if (retval != -ENOEXEC || bprm->mm == NULL) {
1222 break;
1223 #ifdef CONFIG_MODULES
1224 } else {
1225 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1226 if (printable(bprm->buf[0]) &&
1227 printable(bprm->buf[1]) &&
1228 printable(bprm->buf[2]) &&
1229 printable(bprm->buf[3]))
1230 break; /* -ENOEXEC */
1231 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1232 #endif
1235 return retval;
1238 EXPORT_SYMBOL(search_binary_handler);
1240 void free_bprm(struct linux_binprm *bprm)
1242 free_arg_pages(bprm);
1243 if (bprm->cred)
1244 abort_creds(bprm->cred);
1245 kfree(bprm);
1249 * sys_execve() executes a new program.
1251 int do_execve(char * filename,
1252 char __user *__user *argv,
1253 char __user *__user *envp,
1254 struct pt_regs * regs)
1256 struct linux_binprm *bprm;
1257 struct file *file;
1258 struct files_struct *displaced;
1259 bool clear_in_exec;
1260 int retval;
1262 retval = unshare_files(&displaced);
1263 if (retval)
1264 goto out_ret;
1266 retval = -ENOMEM;
1267 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1268 if (!bprm)
1269 goto out_files;
1271 retval = mutex_lock_interruptible(&current->cred_exec_mutex);
1272 if (retval < 0)
1273 goto out_free;
1274 current->in_execve = 1;
1276 retval = -ENOMEM;
1277 bprm->cred = prepare_exec_creds();
1278 if (!bprm->cred)
1279 goto out_unlock;
1281 retval = check_unsafe_exec(bprm);
1282 if (retval < 0)
1283 goto out_unlock;
1284 clear_in_exec = retval;
1286 file = open_exec(filename);
1287 retval = PTR_ERR(file);
1288 if (IS_ERR(file))
1289 goto out_unmark;
1291 sched_exec();
1293 bprm->file = file;
1294 bprm->filename = filename;
1295 bprm->interp = filename;
1297 retval = bprm_mm_init(bprm);
1298 if (retval)
1299 goto out_file;
1301 bprm->argc = count(argv, MAX_ARG_STRINGS);
1302 if ((retval = bprm->argc) < 0)
1303 goto out;
1305 bprm->envc = count(envp, MAX_ARG_STRINGS);
1306 if ((retval = bprm->envc) < 0)
1307 goto out;
1309 retval = prepare_binprm(bprm);
1310 if (retval < 0)
1311 goto out;
1313 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1314 if (retval < 0)
1315 goto out;
1317 bprm->exec = bprm->p;
1318 retval = copy_strings(bprm->envc, envp, bprm);
1319 if (retval < 0)
1320 goto out;
1322 retval = copy_strings(bprm->argc, argv, bprm);
1323 if (retval < 0)
1324 goto out;
1326 current->flags &= ~PF_KTHREAD;
1327 retval = search_binary_handler(bprm,regs);
1328 if (retval < 0)
1329 goto out;
1331 /* execve succeeded */
1332 current->fs->in_exec = 0;
1333 current->in_execve = 0;
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;
1341 out:
1342 if (bprm->mm)
1343 mmput (bprm->mm);
1345 out_file:
1346 if (bprm->file) {
1347 allow_write_access(bprm->file);
1348 fput(bprm->file);
1351 out_unmark:
1352 if (clear_in_exec)
1353 current->fs->in_exec = 0;
1355 out_unlock:
1356 current->in_execve = 0;
1357 mutex_unlock(&current->cred_exec_mutex);
1359 out_free:
1360 free_bprm(bprm);
1362 out_files:
1363 if (displaced)
1364 reset_files_struct(displaced);
1365 out_ret:
1366 return retval;
1369 int set_binfmt(struct linux_binfmt *new)
1371 struct linux_binfmt *old = current->binfmt;
1373 if (new) {
1374 if (!try_module_get(new->module))
1375 return -1;
1377 current->binfmt = new;
1378 if (old)
1379 module_put(old->module);
1380 return 0;
1383 EXPORT_SYMBOL(set_binfmt);
1385 /* format_corename will inspect the pattern parameter, and output a
1386 * name into corename, which must have space for at least
1387 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1389 static int format_corename(char *corename, long signr)
1391 const struct cred *cred = current_cred();
1392 const char *pat_ptr = core_pattern;
1393 int ispipe = (*pat_ptr == '|');
1394 char *out_ptr = corename;
1395 char *const out_end = corename + CORENAME_MAX_SIZE;
1396 int rc;
1397 int pid_in_pattern = 0;
1399 /* Repeat as long as we have more pattern to process and more output
1400 space */
1401 while (*pat_ptr) {
1402 if (*pat_ptr != '%') {
1403 if (out_ptr == out_end)
1404 goto out;
1405 *out_ptr++ = *pat_ptr++;
1406 } else {
1407 switch (*++pat_ptr) {
1408 case 0:
1409 goto out;
1410 /* Double percent, output one percent */
1411 case '%':
1412 if (out_ptr == out_end)
1413 goto out;
1414 *out_ptr++ = '%';
1415 break;
1416 /* pid */
1417 case 'p':
1418 pid_in_pattern = 1;
1419 rc = snprintf(out_ptr, out_end - out_ptr,
1420 "%d", task_tgid_vnr(current));
1421 if (rc > out_end - out_ptr)
1422 goto out;
1423 out_ptr += rc;
1424 break;
1425 /* uid */
1426 case 'u':
1427 rc = snprintf(out_ptr, out_end - out_ptr,
1428 "%d", cred->uid);
1429 if (rc > out_end - out_ptr)
1430 goto out;
1431 out_ptr += rc;
1432 break;
1433 /* gid */
1434 case 'g':
1435 rc = snprintf(out_ptr, out_end - out_ptr,
1436 "%d", cred->gid);
1437 if (rc > out_end - out_ptr)
1438 goto out;
1439 out_ptr += rc;
1440 break;
1441 /* signal that caused the coredump */
1442 case 's':
1443 rc = snprintf(out_ptr, out_end - out_ptr,
1444 "%ld", signr);
1445 if (rc > out_end - out_ptr)
1446 goto out;
1447 out_ptr += rc;
1448 break;
1449 /* UNIX time of coredump */
1450 case 't': {
1451 struct timeval tv;
1452 do_gettimeofday(&tv);
1453 rc = snprintf(out_ptr, out_end - out_ptr,
1454 "%lu", tv.tv_sec);
1455 if (rc > out_end - out_ptr)
1456 goto out;
1457 out_ptr += rc;
1458 break;
1460 /* hostname */
1461 case 'h':
1462 down_read(&uts_sem);
1463 rc = snprintf(out_ptr, out_end - out_ptr,
1464 "%s", utsname()->nodename);
1465 up_read(&uts_sem);
1466 if (rc > out_end - out_ptr)
1467 goto out;
1468 out_ptr += rc;
1469 break;
1470 /* executable */
1471 case 'e':
1472 rc = snprintf(out_ptr, out_end - out_ptr,
1473 "%s", current->comm);
1474 if (rc > out_end - out_ptr)
1475 goto out;
1476 out_ptr += rc;
1477 break;
1478 /* core limit size */
1479 case 'c':
1480 rc = snprintf(out_ptr, out_end - out_ptr,
1481 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1482 if (rc > out_end - out_ptr)
1483 goto out;
1484 out_ptr += rc;
1485 break;
1486 default:
1487 break;
1489 ++pat_ptr;
1492 /* Backward compatibility with core_uses_pid:
1494 * If core_pattern does not include a %p (as is the default)
1495 * and core_uses_pid is set, then .%pid will be appended to
1496 * the filename. Do not do this for piped commands. */
1497 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1498 rc = snprintf(out_ptr, out_end - out_ptr,
1499 ".%d", task_tgid_vnr(current));
1500 if (rc > out_end - out_ptr)
1501 goto out;
1502 out_ptr += rc;
1504 out:
1505 *out_ptr = 0;
1506 return ispipe;
1509 static int zap_process(struct task_struct *start)
1511 struct task_struct *t;
1512 int nr = 0;
1514 start->signal->flags = SIGNAL_GROUP_EXIT;
1515 start->signal->group_stop_count = 0;
1517 t = start;
1518 do {
1519 if (t != current && t->mm) {
1520 sigaddset(&t->pending.signal, SIGKILL);
1521 signal_wake_up(t, 1);
1522 nr++;
1524 } while_each_thread(start, t);
1526 return nr;
1529 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1530 struct core_state *core_state, int exit_code)
1532 struct task_struct *g, *p;
1533 unsigned long flags;
1534 int nr = -EAGAIN;
1536 spin_lock_irq(&tsk->sighand->siglock);
1537 if (!signal_group_exit(tsk->signal)) {
1538 mm->core_state = core_state;
1539 tsk->signal->group_exit_code = exit_code;
1540 nr = zap_process(tsk);
1542 spin_unlock_irq(&tsk->sighand->siglock);
1543 if (unlikely(nr < 0))
1544 return nr;
1546 if (atomic_read(&mm->mm_users) == nr + 1)
1547 goto done;
1549 * We should find and kill all tasks which use this mm, and we should
1550 * count them correctly into ->nr_threads. We don't take tasklist
1551 * lock, but this is safe wrt:
1553 * fork:
1554 * None of sub-threads can fork after zap_process(leader). All
1555 * processes which were created before this point should be
1556 * visible to zap_threads() because copy_process() adds the new
1557 * process to the tail of init_task.tasks list, and lock/unlock
1558 * of ->siglock provides a memory barrier.
1560 * do_exit:
1561 * The caller holds mm->mmap_sem. This means that the task which
1562 * uses this mm can't pass exit_mm(), so it can't exit or clear
1563 * its ->mm.
1565 * de_thread:
1566 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1567 * we must see either old or new leader, this does not matter.
1568 * However, it can change p->sighand, so lock_task_sighand(p)
1569 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1570 * it can't fail.
1572 * Note also that "g" can be the old leader with ->mm == NULL
1573 * and already unhashed and thus removed from ->thread_group.
1574 * This is OK, __unhash_process()->list_del_rcu() does not
1575 * clear the ->next pointer, we will find the new leader via
1576 * next_thread().
1578 rcu_read_lock();
1579 for_each_process(g) {
1580 if (g == tsk->group_leader)
1581 continue;
1582 if (g->flags & PF_KTHREAD)
1583 continue;
1584 p = g;
1585 do {
1586 if (p->mm) {
1587 if (unlikely(p->mm == mm)) {
1588 lock_task_sighand(p, &flags);
1589 nr += zap_process(p);
1590 unlock_task_sighand(p, &flags);
1592 break;
1594 } while_each_thread(g, p);
1596 rcu_read_unlock();
1597 done:
1598 atomic_set(&core_state->nr_threads, nr);
1599 return nr;
1602 static int coredump_wait(int exit_code, struct core_state *core_state)
1604 struct task_struct *tsk = current;
1605 struct mm_struct *mm = tsk->mm;
1606 struct completion *vfork_done;
1607 int core_waiters;
1609 init_completion(&core_state->startup);
1610 core_state->dumper.task = tsk;
1611 core_state->dumper.next = NULL;
1612 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1613 up_write(&mm->mmap_sem);
1615 if (unlikely(core_waiters < 0))
1616 goto fail;
1619 * Make sure nobody is waiting for us to release the VM,
1620 * otherwise we can deadlock when we wait on each other
1622 vfork_done = tsk->vfork_done;
1623 if (vfork_done) {
1624 tsk->vfork_done = NULL;
1625 complete(vfork_done);
1628 if (core_waiters)
1629 wait_for_completion(&core_state->startup);
1630 fail:
1631 return core_waiters;
1634 static void coredump_finish(struct mm_struct *mm)
1636 struct core_thread *curr, *next;
1637 struct task_struct *task;
1639 next = mm->core_state->dumper.next;
1640 while ((curr = next) != NULL) {
1641 next = curr->next;
1642 task = curr->task;
1644 * see exit_mm(), curr->task must not see
1645 * ->task == NULL before we read ->next.
1647 smp_mb();
1648 curr->task = NULL;
1649 wake_up_process(task);
1652 mm->core_state = NULL;
1656 * set_dumpable converts traditional three-value dumpable to two flags and
1657 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1658 * these bits are not changed atomically. So get_dumpable can observe the
1659 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1660 * return either old dumpable or new one by paying attention to the order of
1661 * modifying the bits.
1663 * dumpable | mm->flags (binary)
1664 * old new | initial interim final
1665 * ---------+-----------------------
1666 * 0 1 | 00 01 01
1667 * 0 2 | 00 10(*) 11
1668 * 1 0 | 01 00 00
1669 * 1 2 | 01 11 11
1670 * 2 0 | 11 10(*) 00
1671 * 2 1 | 11 11 01
1673 * (*) get_dumpable regards interim value of 10 as 11.
1675 void set_dumpable(struct mm_struct *mm, int value)
1677 switch (value) {
1678 case 0:
1679 clear_bit(MMF_DUMPABLE, &mm->flags);
1680 smp_wmb();
1681 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1682 break;
1683 case 1:
1684 set_bit(MMF_DUMPABLE, &mm->flags);
1685 smp_wmb();
1686 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1687 break;
1688 case 2:
1689 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1690 smp_wmb();
1691 set_bit(MMF_DUMPABLE, &mm->flags);
1692 break;
1696 int get_dumpable(struct mm_struct *mm)
1698 int ret;
1700 ret = mm->flags & 0x3;
1701 return (ret >= 2) ? 2 : ret;
1704 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1706 struct core_state core_state;
1707 char corename[CORENAME_MAX_SIZE + 1];
1708 struct mm_struct *mm = current->mm;
1709 struct linux_binfmt * binfmt;
1710 struct inode * inode;
1711 struct file * file;
1712 const struct cred *old_cred;
1713 struct cred *cred;
1714 int retval = 0;
1715 int flag = 0;
1716 int ispipe = 0;
1717 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1718 char **helper_argv = NULL;
1719 int helper_argc = 0;
1720 char *delimit;
1722 audit_core_dumps(signr);
1724 binfmt = current->binfmt;
1725 if (!binfmt || !binfmt->core_dump)
1726 goto fail;
1728 cred = prepare_creds();
1729 if (!cred) {
1730 retval = -ENOMEM;
1731 goto fail;
1734 down_write(&mm->mmap_sem);
1736 * If another thread got here first, or we are not dumpable, bail out.
1738 if (mm->core_state || !get_dumpable(mm)) {
1739 up_write(&mm->mmap_sem);
1740 put_cred(cred);
1741 goto fail;
1745 * We cannot trust fsuid as being the "true" uid of the
1746 * process nor do we know its entire history. We only know it
1747 * was tainted so we dump it as root in mode 2.
1749 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1750 flag = O_EXCL; /* Stop rewrite attacks */
1751 cred->fsuid = 0; /* Dump root private */
1754 retval = coredump_wait(exit_code, &core_state);
1755 if (retval < 0) {
1756 put_cred(cred);
1757 goto fail;
1760 old_cred = override_creds(cred);
1763 * Clear any false indication of pending signals that might
1764 * be seen by the filesystem code called to write the core file.
1766 clear_thread_flag(TIF_SIGPENDING);
1769 * lock_kernel() because format_corename() is controlled by sysctl, which
1770 * uses lock_kernel()
1772 lock_kernel();
1773 ispipe = format_corename(corename, signr);
1774 unlock_kernel();
1776 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1777 * to a pipe. Since we're not writing directly to the filesystem
1778 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1779 * created unless the pipe reader choses to write out the core file
1780 * at which point file size limits and permissions will be imposed
1781 * as it does with any other process
1783 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1784 goto fail_unlock;
1786 if (ispipe) {
1787 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1788 if (!helper_argv) {
1789 printk(KERN_WARNING "%s failed to allocate memory\n",
1790 __func__);
1791 goto fail_unlock;
1793 /* Terminate the string before the first option */
1794 delimit = strchr(corename, ' ');
1795 if (delimit)
1796 *delimit = '\0';
1797 delimit = strrchr(helper_argv[0], '/');
1798 if (delimit)
1799 delimit++;
1800 else
1801 delimit = helper_argv[0];
1802 if (!strcmp(delimit, current->comm)) {
1803 printk(KERN_NOTICE "Recursive core dump detected, "
1804 "aborting\n");
1805 goto fail_unlock;
1808 core_limit = RLIM_INFINITY;
1810 /* SIGPIPE can happen, but it's just never processed */
1811 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1812 &file)) {
1813 printk(KERN_INFO "Core dump to %s pipe failed\n",
1814 corename);
1815 goto fail_unlock;
1817 } else
1818 file = filp_open(corename,
1819 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1820 0600);
1821 if (IS_ERR(file))
1822 goto fail_unlock;
1823 inode = file->f_path.dentry->d_inode;
1824 if (inode->i_nlink > 1)
1825 goto close_fail; /* multiple links - don't dump */
1826 if (!ispipe && d_unhashed(file->f_path.dentry))
1827 goto close_fail;
1829 /* AK: actually i see no reason to not allow this for named pipes etc.,
1830 but keep the previous behaviour for now. */
1831 if (!ispipe && !S_ISREG(inode->i_mode))
1832 goto close_fail;
1834 * Dont allow local users get cute and trick others to coredump
1835 * into their pre-created files:
1837 if (inode->i_uid != current_fsuid())
1838 goto close_fail;
1839 if (!file->f_op)
1840 goto close_fail;
1841 if (!file->f_op->write)
1842 goto close_fail;
1843 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1844 goto close_fail;
1846 retval = binfmt->core_dump(signr, regs, file, core_limit);
1848 if (retval)
1849 current->signal->group_exit_code |= 0x80;
1850 close_fail:
1851 filp_close(file, NULL);
1852 fail_unlock:
1853 if (helper_argv)
1854 argv_free(helper_argv);
1856 revert_creds(old_cred);
1857 put_cred(cred);
1858 coredump_finish(mm);
1859 fail:
1860 return;