4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * #!-checking implemented by tytso.
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
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/fdtable.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>
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)
76 write_lock(&binfmt_lock);
77 list_add(&fmt->lh, &formats);
78 write_unlock(&binfmt_lock);
82 EXPORT_SYMBOL(register_binfmt);
84 void unregister_binfmt(struct linux_binfmt * fmt)
86 write_lock(&binfmt_lock);
88 write_unlock(&binfmt_lock);
91 EXPORT_SYMBOL(unregister_binfmt);
93 static inline void put_binfmt(struct linux_binfmt * fmt)
95 module_put(fmt->module);
99 * Note that a shared library must be both readable and executable due to
102 * Also note that we take the address to load from from the file itself.
104 SYSCALL_DEFINE1(uselib, const char __user *, library)
108 char *tmp = getname(library);
109 int error = PTR_ERR(tmp);
112 error = path_lookup_open(AT_FDCWD, tmp,
114 FMODE_READ|FMODE_EXEC);
121 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
125 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
128 error = inode_permission(nd.path.dentry->d_inode,
129 MAY_READ | MAY_EXEC | MAY_OPEN);
132 error = ima_path_check(&nd.path, MAY_READ | MAY_EXEC | MAY_OPEN);
136 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
137 error = PTR_ERR(file);
141 fsnotify_open(file->f_path.dentry);
145 struct linux_binfmt * fmt;
147 read_lock(&binfmt_lock);
148 list_for_each_entry(fmt, &formats, lh) {
149 if (!fmt->load_shlib)
151 if (!try_module_get(fmt->module))
153 read_unlock(&binfmt_lock);
154 error = fmt->load_shlib(file);
155 read_lock(&binfmt_lock);
157 if (error != -ENOEXEC)
160 read_unlock(&binfmt_lock);
166 release_open_intent(&nd);
173 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
179 #ifdef CONFIG_STACK_GROWSUP
181 ret = expand_stack_downwards(bprm->vma, pos);
186 ret = get_user_pages(current, bprm->mm, pos,
187 1, write, 1, &page, NULL);
192 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
196 * We've historically supported up to 32 pages (ARG_MAX)
197 * of argument strings even with small stacks
203 * Limit to 1/4-th the stack size for the argv+env strings.
205 * - the remaining binfmt code will not run out of stack space,
206 * - the program will have a reasonable amount of stack left
209 rlim = current->signal->rlim;
210 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
219 static void put_arg_page(struct page *page)
224 static void free_arg_page(struct linux_binprm *bprm, int i)
228 static void free_arg_pages(struct linux_binprm *bprm)
232 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
235 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
238 static int __bprm_mm_init(struct linux_binprm *bprm)
241 struct vm_area_struct *vma = NULL;
242 struct mm_struct *mm = bprm->mm;
244 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
248 down_write(&mm->mmap_sem);
252 * Place the stack at the largest stack address the architecture
253 * supports. Later, we'll move this to an appropriate place. We don't
254 * use STACK_TOP because that can depend on attributes which aren't
257 vma->vm_end = STACK_TOP_MAX;
258 vma->vm_start = vma->vm_end - PAGE_SIZE;
259 vma->vm_flags = VM_STACK_FLAGS;
260 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
261 err = insert_vm_struct(mm, vma);
265 mm->stack_vm = mm->total_vm = 1;
266 up_write(&mm->mmap_sem);
267 bprm->p = vma->vm_end - sizeof(void *);
270 up_write(&mm->mmap_sem);
272 kmem_cache_free(vm_area_cachep, vma);
276 static bool valid_arg_len(struct linux_binprm *bprm, long len)
278 return len <= MAX_ARG_STRLEN;
283 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
288 page = bprm->page[pos / PAGE_SIZE];
289 if (!page && write) {
290 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
293 bprm->page[pos / PAGE_SIZE] = page;
299 static void put_arg_page(struct page *page)
303 static void free_arg_page(struct linux_binprm *bprm, int i)
306 __free_page(bprm->page[i]);
307 bprm->page[i] = NULL;
311 static void free_arg_pages(struct linux_binprm *bprm)
315 for (i = 0; i < MAX_ARG_PAGES; i++)
316 free_arg_page(bprm, i);
319 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
324 static int __bprm_mm_init(struct linux_binprm *bprm)
326 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
330 static bool valid_arg_len(struct linux_binprm *bprm, long len)
332 return len <= bprm->p;
335 #endif /* CONFIG_MMU */
338 * Create a new mm_struct and populate it with a temporary stack
339 * vm_area_struct. We don't have enough context at this point to set the stack
340 * flags, permissions, and offset, so we use temporary values. We'll update
341 * them later in setup_arg_pages().
343 int bprm_mm_init(struct linux_binprm *bprm)
346 struct mm_struct *mm = NULL;
348 bprm->mm = mm = mm_alloc();
353 err = init_new_context(current, mm);
357 err = __bprm_mm_init(bprm);
373 * count() counts the number of strings in array ARGV.
375 static int count(char __user * __user * argv, int max)
383 if (get_user(p, argv))
397 * 'copy_strings()' copies argument/environment strings from the old
398 * processes's memory to the new process's stack. The call to get_user_pages()
399 * ensures the destination page is created and not swapped out.
401 static int copy_strings(int argc, char __user * __user * argv,
402 struct linux_binprm *bprm)
404 struct page *kmapped_page = NULL;
406 unsigned long kpos = 0;
414 if (get_user(str, argv+argc) ||
415 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
420 if (!valid_arg_len(bprm, len)) {
425 /* We're going to work our way backwords. */
431 int offset, bytes_to_copy;
433 offset = pos % PAGE_SIZE;
437 bytes_to_copy = offset;
438 if (bytes_to_copy > len)
441 offset -= bytes_to_copy;
442 pos -= bytes_to_copy;
443 str -= bytes_to_copy;
444 len -= bytes_to_copy;
446 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
449 page = get_arg_page(bprm, pos, 1);
456 flush_kernel_dcache_page(kmapped_page);
457 kunmap(kmapped_page);
458 put_arg_page(kmapped_page);
461 kaddr = kmap(kmapped_page);
462 kpos = pos & PAGE_MASK;
463 flush_arg_page(bprm, kpos, kmapped_page);
465 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
474 flush_kernel_dcache_page(kmapped_page);
475 kunmap(kmapped_page);
476 put_arg_page(kmapped_page);
482 * Like copy_strings, but get argv and its values from kernel memory.
484 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
487 mm_segment_t oldfs = get_fs();
489 r = copy_strings(argc, (char __user * __user *)argv, bprm);
493 EXPORT_SYMBOL(copy_strings_kernel);
498 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
499 * the binfmt code determines where the new stack should reside, we shift it to
500 * its final location. The process proceeds as follows:
502 * 1) Use shift to calculate the new vma endpoints.
503 * 2) Extend vma to cover both the old and new ranges. This ensures the
504 * arguments passed to subsequent functions are consistent.
505 * 3) Move vma's page tables to the new range.
506 * 4) Free up any cleared pgd range.
507 * 5) Shrink the vma to cover only the new range.
509 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
511 struct mm_struct *mm = vma->vm_mm;
512 unsigned long old_start = vma->vm_start;
513 unsigned long old_end = vma->vm_end;
514 unsigned long length = old_end - old_start;
515 unsigned long new_start = old_start - shift;
516 unsigned long new_end = old_end - shift;
517 struct mmu_gather *tlb;
519 BUG_ON(new_start > new_end);
522 * ensure there are no vmas between where we want to go
525 if (vma != find_vma(mm, new_start))
529 * cover the whole range: [new_start, old_end)
531 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
534 * move the page tables downwards, on failure we rely on
535 * process cleanup to remove whatever mess we made.
537 if (length != move_page_tables(vma, old_start,
538 vma, new_start, length))
542 tlb = tlb_gather_mmu(mm, 0);
543 if (new_end > old_start) {
545 * when the old and new regions overlap clear from new_end.
547 free_pgd_range(tlb, new_end, old_end, new_end,
548 vma->vm_next ? vma->vm_next->vm_start : 0);
551 * otherwise, clean from old_start; this is done to not touch
552 * the address space in [new_end, old_start) some architectures
553 * have constraints on va-space that make this illegal (IA64) -
554 * for the others its just a little faster.
556 free_pgd_range(tlb, old_start, old_end, new_end,
557 vma->vm_next ? vma->vm_next->vm_start : 0);
559 tlb_finish_mmu(tlb, new_end, old_end);
562 * shrink the vma to just the new range.
564 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
569 #define EXTRA_STACK_VM_PAGES 20 /* random */
572 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
573 * the stack is optionally relocated, and some extra space is added.
575 int setup_arg_pages(struct linux_binprm *bprm,
576 unsigned long stack_top,
577 int executable_stack)
580 unsigned long stack_shift;
581 struct mm_struct *mm = current->mm;
582 struct vm_area_struct *vma = bprm->vma;
583 struct vm_area_struct *prev = NULL;
584 unsigned long vm_flags;
585 unsigned long stack_base;
587 #ifdef CONFIG_STACK_GROWSUP
588 /* Limit stack size to 1GB */
589 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
590 if (stack_base > (1 << 30))
591 stack_base = 1 << 30;
593 /* Make sure we didn't let the argument array grow too large. */
594 if (vma->vm_end - vma->vm_start > stack_base)
597 stack_base = PAGE_ALIGN(stack_top - stack_base);
599 stack_shift = vma->vm_start - stack_base;
600 mm->arg_start = bprm->p - stack_shift;
601 bprm->p = vma->vm_end - stack_shift;
603 stack_top = arch_align_stack(stack_top);
604 stack_top = PAGE_ALIGN(stack_top);
605 stack_shift = vma->vm_end - stack_top;
607 bprm->p -= stack_shift;
608 mm->arg_start = bprm->p;
612 bprm->loader -= stack_shift;
613 bprm->exec -= stack_shift;
615 down_write(&mm->mmap_sem);
616 vm_flags = VM_STACK_FLAGS;
619 * Adjust stack execute permissions; explicitly enable for
620 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
621 * (arch default) otherwise.
623 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
625 else if (executable_stack == EXSTACK_DISABLE_X)
626 vm_flags &= ~VM_EXEC;
627 vm_flags |= mm->def_flags;
629 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
635 /* Move stack pages down in memory. */
637 ret = shift_arg_pages(vma, stack_shift);
639 up_write(&mm->mmap_sem);
644 #ifdef CONFIG_STACK_GROWSUP
645 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
647 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
649 ret = expand_stack(vma, stack_base);
654 up_write(&mm->mmap_sem);
657 EXPORT_SYMBOL(setup_arg_pages);
659 #endif /* CONFIG_MMU */
661 struct file *open_exec(const char *name)
667 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
668 FMODE_READ|FMODE_EXEC);
673 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
676 if (nd.path.mnt->mnt_flags & MNT_NOEXEC)
679 err = inode_permission(nd.path.dentry->d_inode, MAY_EXEC | MAY_OPEN);
682 err = ima_path_check(&nd.path, MAY_EXEC | MAY_OPEN);
686 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
690 fsnotify_open(file->f_path.dentry);
692 err = deny_write_access(file);
701 release_open_intent(&nd);
706 EXPORT_SYMBOL(open_exec);
708 int kernel_read(struct file *file, unsigned long offset,
709 char *addr, unsigned long count)
717 /* The cast to a user pointer is valid due to the set_fs() */
718 result = vfs_read(file, (void __user *)addr, count, &pos);
723 EXPORT_SYMBOL(kernel_read);
725 static int exec_mmap(struct mm_struct *mm)
727 struct task_struct *tsk;
728 struct mm_struct * old_mm, *active_mm;
730 /* Notify parent that we're no longer interested in the old VM */
732 old_mm = current->mm;
733 mm_release(tsk, old_mm);
737 * Make sure that if there is a core dump in progress
738 * for the old mm, we get out and die instead of going
739 * through with the exec. We must hold mmap_sem around
740 * checking core_state and changing tsk->mm.
742 down_read(&old_mm->mmap_sem);
743 if (unlikely(old_mm->core_state)) {
744 up_read(&old_mm->mmap_sem);
749 active_mm = tsk->active_mm;
752 activate_mm(active_mm, mm);
754 arch_pick_mmap_layout(mm);
756 up_read(&old_mm->mmap_sem);
757 BUG_ON(active_mm != old_mm);
758 mm_update_next_owner(old_mm);
767 * This function makes sure the current process has its own signal table,
768 * so that flush_signal_handlers can later reset the handlers without
769 * disturbing other processes. (Other processes might share the signal
770 * table via the CLONE_SIGHAND option to clone().)
772 static int de_thread(struct task_struct *tsk)
774 struct signal_struct *sig = tsk->signal;
775 struct sighand_struct *oldsighand = tsk->sighand;
776 spinlock_t *lock = &oldsighand->siglock;
779 if (thread_group_empty(tsk))
780 goto no_thread_group;
783 * Kill all other threads in the thread group.
786 if (signal_group_exit(sig)) {
788 * Another group action in progress, just
789 * return so that the signal is processed.
791 spin_unlock_irq(lock);
794 sig->group_exit_task = tsk;
795 zap_other_threads(tsk);
797 /* Account for the thread group leader hanging around: */
798 count = thread_group_leader(tsk) ? 1 : 2;
799 sig->notify_count = count;
800 while (atomic_read(&sig->count) > count) {
801 __set_current_state(TASK_UNINTERRUPTIBLE);
802 spin_unlock_irq(lock);
806 spin_unlock_irq(lock);
809 * At this point all other threads have exited, all we have to
810 * do is to wait for the thread group leader to become inactive,
811 * and to assume its PID:
813 if (!thread_group_leader(tsk)) {
814 struct task_struct *leader = tsk->group_leader;
816 sig->notify_count = -1; /* for exit_notify() */
818 write_lock_irq(&tasklist_lock);
819 if (likely(leader->exit_state))
821 __set_current_state(TASK_UNINTERRUPTIBLE);
822 write_unlock_irq(&tasklist_lock);
827 * The only record we have of the real-time age of a
828 * process, regardless of execs it's done, is start_time.
829 * All the past CPU time is accumulated in signal_struct
830 * from sister threads now dead. But in this non-leader
831 * exec, nothing survives from the original leader thread,
832 * whose birth marks the true age of this process now.
833 * When we take on its identity by switching to its PID, we
834 * also take its birthdate (always earlier than our own).
836 tsk->start_time = leader->start_time;
838 BUG_ON(!same_thread_group(leader, tsk));
839 BUG_ON(has_group_leader_pid(tsk));
841 * An exec() starts a new thread group with the
842 * TGID of the previous thread group. Rehash the
843 * two threads with a switched PID, and release
844 * the former thread group leader:
847 /* Become a process group leader with the old leader's pid.
848 * The old leader becomes a thread of the this thread group.
849 * Note: The old leader also uses this pid until release_task
850 * is called. Odd but simple and correct.
852 detach_pid(tsk, PIDTYPE_PID);
853 tsk->pid = leader->pid;
854 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
855 transfer_pid(leader, tsk, PIDTYPE_PGID);
856 transfer_pid(leader, tsk, PIDTYPE_SID);
857 list_replace_rcu(&leader->tasks, &tsk->tasks);
859 tsk->group_leader = tsk;
860 leader->group_leader = tsk;
862 tsk->exit_signal = SIGCHLD;
864 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
865 leader->exit_state = EXIT_DEAD;
866 write_unlock_irq(&tasklist_lock);
868 release_task(leader);
871 sig->group_exit_task = NULL;
872 sig->notify_count = 0;
876 flush_itimer_signals();
878 if (atomic_read(&oldsighand->count) != 1) {
879 struct sighand_struct *newsighand;
881 * This ->sighand is shared with the CLONE_SIGHAND
882 * but not CLONE_THREAD task, switch to the new one.
884 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
888 atomic_set(&newsighand->count, 1);
889 memcpy(newsighand->action, oldsighand->action,
890 sizeof(newsighand->action));
892 write_lock_irq(&tasklist_lock);
893 spin_lock(&oldsighand->siglock);
894 rcu_assign_pointer(tsk->sighand, newsighand);
895 spin_unlock(&oldsighand->siglock);
896 write_unlock_irq(&tasklist_lock);
898 __cleanup_sighand(oldsighand);
901 BUG_ON(!thread_group_leader(tsk));
906 * These functions flushes out all traces of the currently running executable
907 * so that a new one can be started
909 static void flush_old_files(struct files_struct * files)
914 spin_lock(&files->file_lock);
916 unsigned long set, i;
920 fdt = files_fdtable(files);
921 if (i >= fdt->max_fds)
923 set = fdt->close_on_exec->fds_bits[j];
926 fdt->close_on_exec->fds_bits[j] = 0;
927 spin_unlock(&files->file_lock);
928 for ( ; set ; i++,set >>= 1) {
933 spin_lock(&files->file_lock);
936 spin_unlock(&files->file_lock);
939 char *get_task_comm(char *buf, struct task_struct *tsk)
941 /* buf must be at least sizeof(tsk->comm) in size */
943 strncpy(buf, tsk->comm, sizeof(tsk->comm));
948 void set_task_comm(struct task_struct *tsk, char *buf)
951 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
955 int flush_old_exec(struct linux_binprm * bprm)
959 char tcomm[sizeof(current->comm)];
962 * Make sure we have a private signal table and that
963 * we are unassociated from the previous thread group.
965 retval = de_thread(current);
969 set_mm_exe_file(bprm->mm, bprm->file);
972 * Release all of the old mmap stuff
974 retval = exec_mmap(bprm->mm);
978 bprm->mm = NULL; /* We're using it now */
980 /* This is the point of no return */
981 current->sas_ss_sp = current->sas_ss_size = 0;
983 if (current_euid() == current_uid() && current_egid() == current_gid())
984 set_dumpable(current->mm, 1);
986 set_dumpable(current->mm, suid_dumpable);
988 name = bprm->filename;
990 /* Copies the binary name from after last slash */
991 for (i=0; (ch = *(name++)) != '\0';) {
993 i = 0; /* overwrite what we wrote */
995 if (i < (sizeof(tcomm) - 1))
999 set_task_comm(current, tcomm);
1001 current->flags &= ~PF_RANDOMIZE;
1004 /* Set the new mm task size. We have to do that late because it may
1005 * depend on TIF_32BIT which is only updated in flush_thread() on
1006 * some architectures like powerpc
1008 current->mm->task_size = TASK_SIZE;
1010 /* install the new credentials */
1011 if (bprm->cred->uid != current_euid() ||
1012 bprm->cred->gid != current_egid()) {
1013 current->pdeath_signal = 0;
1014 } else if (file_permission(bprm->file, MAY_READ) ||
1015 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1016 set_dumpable(current->mm, suid_dumpable);
1019 current->personality &= ~bprm->per_clear;
1021 /* An exec changes our domain. We are no longer part of the thread
1024 current->self_exec_id++;
1026 flush_signal_handlers(current, 0);
1027 flush_old_files(current->files);
1035 EXPORT_SYMBOL(flush_old_exec);
1038 * install the new credentials for this executable
1040 void install_exec_creds(struct linux_binprm *bprm)
1042 security_bprm_committing_creds(bprm);
1044 commit_creds(bprm->cred);
1047 /* cred_exec_mutex must be held at least to this point to prevent
1048 * ptrace_attach() from altering our determination of the task's
1049 * credentials; any time after this it may be unlocked */
1051 security_bprm_committed_creds(bprm);
1053 EXPORT_SYMBOL(install_exec_creds);
1056 * determine how safe it is to execute the proposed program
1057 * - the caller must hold current->cred_exec_mutex to protect against
1060 int check_unsafe_exec(struct linux_binprm *bprm)
1062 struct task_struct *p = current, *t;
1063 unsigned long flags;
1067 bprm->unsafe = tracehook_unsafe_exec(p);
1070 write_lock(&p->fs->lock);
1071 lock_task_sighand(p, &flags);
1072 for (t = next_thread(p); t != p; t = next_thread(t)) {
1077 if (p->fs->users > n_fs) {
1078 bprm->unsafe |= LSM_UNSAFE_SHARE;
1085 unlock_task_sighand(p, &flags);
1086 write_unlock(&p->fs->lock);
1092 * Fill the binprm structure from the inode.
1093 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1095 * This may be called multiple times for binary chains (scripts for example).
1097 int prepare_binprm(struct linux_binprm *bprm)
1100 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1103 mode = inode->i_mode;
1104 if (bprm->file->f_op == NULL)
1107 /* clear any previous set[ug]id data from a previous binary */
1108 bprm->cred->euid = current_euid();
1109 bprm->cred->egid = current_egid();
1111 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1113 if (mode & S_ISUID) {
1114 bprm->per_clear |= PER_CLEAR_ON_SETID;
1115 bprm->cred->euid = inode->i_uid;
1120 * If setgid is set but no group execute bit then this
1121 * is a candidate for mandatory locking, not a setgid
1124 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1125 bprm->per_clear |= PER_CLEAR_ON_SETID;
1126 bprm->cred->egid = inode->i_gid;
1130 /* fill in binprm security blob */
1131 retval = security_bprm_set_creds(bprm);
1134 bprm->cred_prepared = 1;
1136 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1137 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1140 EXPORT_SYMBOL(prepare_binprm);
1143 * Arguments are '\0' separated strings found at the location bprm->p
1144 * points to; chop off the first by relocating brpm->p to right after
1145 * the first '\0' encountered.
1147 int remove_arg_zero(struct linux_binprm *bprm)
1150 unsigned long offset;
1158 offset = bprm->p & ~PAGE_MASK;
1159 page = get_arg_page(bprm, bprm->p, 0);
1164 kaddr = kmap_atomic(page, KM_USER0);
1166 for (; offset < PAGE_SIZE && kaddr[offset];
1167 offset++, bprm->p++)
1170 kunmap_atomic(kaddr, KM_USER0);
1173 if (offset == PAGE_SIZE)
1174 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1175 } while (offset == PAGE_SIZE);
1184 EXPORT_SYMBOL(remove_arg_zero);
1187 * cycle the list of binary formats handler, until one recognizes the image
1189 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1191 unsigned int depth = bprm->recursion_depth;
1193 struct linux_binfmt *fmt;
1195 retval = security_bprm_check(bprm);
1198 retval = ima_bprm_check(bprm);
1202 /* kernel module loader fixup */
1203 /* so we don't try to load run modprobe in kernel space. */
1206 retval = audit_bprm(bprm);
1211 for (try=0; try<2; try++) {
1212 read_lock(&binfmt_lock);
1213 list_for_each_entry(fmt, &formats, lh) {
1214 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1217 if (!try_module_get(fmt->module))
1219 read_unlock(&binfmt_lock);
1220 retval = fn(bprm, regs);
1222 * Restore the depth counter to its starting value
1223 * in this call, so we don't have to rely on every
1224 * load_binary function to restore it on return.
1226 bprm->recursion_depth = depth;
1229 tracehook_report_exec(fmt, bprm, regs);
1231 allow_write_access(bprm->file);
1235 current->did_exec = 1;
1236 proc_exec_connector(current);
1239 read_lock(&binfmt_lock);
1241 if (retval != -ENOEXEC || bprm->mm == NULL)
1244 read_unlock(&binfmt_lock);
1248 read_unlock(&binfmt_lock);
1249 if (retval != -ENOEXEC || bprm->mm == NULL) {
1251 #ifdef CONFIG_MODULES
1253 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1254 if (printable(bprm->buf[0]) &&
1255 printable(bprm->buf[1]) &&
1256 printable(bprm->buf[2]) &&
1257 printable(bprm->buf[3]))
1258 break; /* -ENOEXEC */
1259 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1266 EXPORT_SYMBOL(search_binary_handler);
1268 void free_bprm(struct linux_binprm *bprm)
1270 free_arg_pages(bprm);
1272 abort_creds(bprm->cred);
1277 * sys_execve() executes a new program.
1279 int do_execve(char * filename,
1280 char __user *__user *argv,
1281 char __user *__user *envp,
1282 struct pt_regs * regs)
1284 struct linux_binprm *bprm;
1286 struct files_struct *displaced;
1289 retval = unshare_files(&displaced);
1294 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1298 retval = mutex_lock_interruptible(¤t->cred_exec_mutex);
1301 current->in_execve = 1;
1304 bprm->cred = prepare_exec_creds();
1308 retval = check_unsafe_exec(bprm);
1312 file = open_exec(filename);
1313 retval = PTR_ERR(file);
1320 bprm->filename = filename;
1321 bprm->interp = filename;
1323 retval = bprm_mm_init(bprm);
1327 bprm->argc = count(argv, MAX_ARG_STRINGS);
1328 if ((retval = bprm->argc) < 0)
1331 bprm->envc = count(envp, MAX_ARG_STRINGS);
1332 if ((retval = bprm->envc) < 0)
1335 retval = prepare_binprm(bprm);
1339 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1343 bprm->exec = bprm->p;
1344 retval = copy_strings(bprm->envc, envp, bprm);
1348 retval = copy_strings(bprm->argc, argv, bprm);
1352 current->flags &= ~PF_KTHREAD;
1353 retval = search_binary_handler(bprm,regs);
1357 /* execve succeeded */
1358 write_lock(¤t->fs->lock);
1359 current->fs->in_exec = 0;
1360 write_unlock(¤t->fs->lock);
1361 current->in_execve = 0;
1362 mutex_unlock(¤t->cred_exec_mutex);
1363 acct_update_integrals(current);
1366 put_files_struct(displaced);
1375 allow_write_access(bprm->file);
1380 write_lock(¤t->fs->lock);
1381 current->fs->in_exec = 0;
1382 write_unlock(¤t->fs->lock);
1385 current->in_execve = 0;
1386 mutex_unlock(¤t->cred_exec_mutex);
1393 reset_files_struct(displaced);
1398 int set_binfmt(struct linux_binfmt *new)
1400 struct linux_binfmt *old = current->binfmt;
1403 if (!try_module_get(new->module))
1406 current->binfmt = new;
1408 module_put(old->module);
1412 EXPORT_SYMBOL(set_binfmt);
1414 /* format_corename will inspect the pattern parameter, and output a
1415 * name into corename, which must have space for at least
1416 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1418 static int format_corename(char *corename, long signr)
1420 const struct cred *cred = current_cred();
1421 const char *pat_ptr = core_pattern;
1422 int ispipe = (*pat_ptr == '|');
1423 char *out_ptr = corename;
1424 char *const out_end = corename + CORENAME_MAX_SIZE;
1426 int pid_in_pattern = 0;
1428 /* Repeat as long as we have more pattern to process and more output
1431 if (*pat_ptr != '%') {
1432 if (out_ptr == out_end)
1434 *out_ptr++ = *pat_ptr++;
1436 switch (*++pat_ptr) {
1439 /* Double percent, output one percent */
1441 if (out_ptr == out_end)
1448 rc = snprintf(out_ptr, out_end - out_ptr,
1449 "%d", task_tgid_vnr(current));
1450 if (rc > out_end - out_ptr)
1456 rc = snprintf(out_ptr, out_end - out_ptr,
1458 if (rc > out_end - out_ptr)
1464 rc = snprintf(out_ptr, out_end - out_ptr,
1466 if (rc > out_end - out_ptr)
1470 /* signal that caused the coredump */
1472 rc = snprintf(out_ptr, out_end - out_ptr,
1474 if (rc > out_end - out_ptr)
1478 /* UNIX time of coredump */
1481 do_gettimeofday(&tv);
1482 rc = snprintf(out_ptr, out_end - out_ptr,
1484 if (rc > out_end - out_ptr)
1491 down_read(&uts_sem);
1492 rc = snprintf(out_ptr, out_end - out_ptr,
1493 "%s", utsname()->nodename);
1495 if (rc > out_end - out_ptr)
1501 rc = snprintf(out_ptr, out_end - out_ptr,
1502 "%s", current->comm);
1503 if (rc > out_end - out_ptr)
1507 /* core limit size */
1509 rc = snprintf(out_ptr, out_end - out_ptr,
1510 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1511 if (rc > out_end - out_ptr)
1521 /* Backward compatibility with core_uses_pid:
1523 * If core_pattern does not include a %p (as is the default)
1524 * and core_uses_pid is set, then .%pid will be appended to
1525 * the filename. Do not do this for piped commands. */
1526 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1527 rc = snprintf(out_ptr, out_end - out_ptr,
1528 ".%d", task_tgid_vnr(current));
1529 if (rc > out_end - out_ptr)
1538 static int zap_process(struct task_struct *start)
1540 struct task_struct *t;
1543 start->signal->flags = SIGNAL_GROUP_EXIT;
1544 start->signal->group_stop_count = 0;
1548 if (t != current && t->mm) {
1549 sigaddset(&t->pending.signal, SIGKILL);
1550 signal_wake_up(t, 1);
1553 } while_each_thread(start, t);
1558 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1559 struct core_state *core_state, int exit_code)
1561 struct task_struct *g, *p;
1562 unsigned long flags;
1565 spin_lock_irq(&tsk->sighand->siglock);
1566 if (!signal_group_exit(tsk->signal)) {
1567 mm->core_state = core_state;
1568 tsk->signal->group_exit_code = exit_code;
1569 nr = zap_process(tsk);
1571 spin_unlock_irq(&tsk->sighand->siglock);
1572 if (unlikely(nr < 0))
1575 if (atomic_read(&mm->mm_users) == nr + 1)
1578 * We should find and kill all tasks which use this mm, and we should
1579 * count them correctly into ->nr_threads. We don't take tasklist
1580 * lock, but this is safe wrt:
1583 * None of sub-threads can fork after zap_process(leader). All
1584 * processes which were created before this point should be
1585 * visible to zap_threads() because copy_process() adds the new
1586 * process to the tail of init_task.tasks list, and lock/unlock
1587 * of ->siglock provides a memory barrier.
1590 * The caller holds mm->mmap_sem. This means that the task which
1591 * uses this mm can't pass exit_mm(), so it can't exit or clear
1595 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1596 * we must see either old or new leader, this does not matter.
1597 * However, it can change p->sighand, so lock_task_sighand(p)
1598 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1601 * Note also that "g" can be the old leader with ->mm == NULL
1602 * and already unhashed and thus removed from ->thread_group.
1603 * This is OK, __unhash_process()->list_del_rcu() does not
1604 * clear the ->next pointer, we will find the new leader via
1608 for_each_process(g) {
1609 if (g == tsk->group_leader)
1611 if (g->flags & PF_KTHREAD)
1616 if (unlikely(p->mm == mm)) {
1617 lock_task_sighand(p, &flags);
1618 nr += zap_process(p);
1619 unlock_task_sighand(p, &flags);
1623 } while_each_thread(g, p);
1627 atomic_set(&core_state->nr_threads, nr);
1631 static int coredump_wait(int exit_code, struct core_state *core_state)
1633 struct task_struct *tsk = current;
1634 struct mm_struct *mm = tsk->mm;
1635 struct completion *vfork_done;
1638 init_completion(&core_state->startup);
1639 core_state->dumper.task = tsk;
1640 core_state->dumper.next = NULL;
1641 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1642 up_write(&mm->mmap_sem);
1644 if (unlikely(core_waiters < 0))
1648 * Make sure nobody is waiting for us to release the VM,
1649 * otherwise we can deadlock when we wait on each other
1651 vfork_done = tsk->vfork_done;
1653 tsk->vfork_done = NULL;
1654 complete(vfork_done);
1658 wait_for_completion(&core_state->startup);
1660 return core_waiters;
1663 static void coredump_finish(struct mm_struct *mm)
1665 struct core_thread *curr, *next;
1666 struct task_struct *task;
1668 next = mm->core_state->dumper.next;
1669 while ((curr = next) != NULL) {
1673 * see exit_mm(), curr->task must not see
1674 * ->task == NULL before we read ->next.
1678 wake_up_process(task);
1681 mm->core_state = NULL;
1685 * set_dumpable converts traditional three-value dumpable to two flags and
1686 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1687 * these bits are not changed atomically. So get_dumpable can observe the
1688 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1689 * return either old dumpable or new one by paying attention to the order of
1690 * modifying the bits.
1692 * dumpable | mm->flags (binary)
1693 * old new | initial interim final
1694 * ---------+-----------------------
1702 * (*) get_dumpable regards interim value of 10 as 11.
1704 void set_dumpable(struct mm_struct *mm, int value)
1708 clear_bit(MMF_DUMPABLE, &mm->flags);
1710 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1713 set_bit(MMF_DUMPABLE, &mm->flags);
1715 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1718 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1720 set_bit(MMF_DUMPABLE, &mm->flags);
1725 int get_dumpable(struct mm_struct *mm)
1729 ret = mm->flags & 0x3;
1730 return (ret >= 2) ? 2 : ret;
1733 void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1735 struct core_state core_state;
1736 char corename[CORENAME_MAX_SIZE + 1];
1737 struct mm_struct *mm = current->mm;
1738 struct linux_binfmt * binfmt;
1739 struct inode * inode;
1741 const struct cred *old_cred;
1746 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1747 char **helper_argv = NULL;
1748 int helper_argc = 0;
1751 audit_core_dumps(signr);
1753 binfmt = current->binfmt;
1754 if (!binfmt || !binfmt->core_dump)
1757 cred = prepare_creds();
1763 down_write(&mm->mmap_sem);
1765 * If another thread got here first, or we are not dumpable, bail out.
1767 if (mm->core_state || !get_dumpable(mm)) {
1768 up_write(&mm->mmap_sem);
1774 * We cannot trust fsuid as being the "true" uid of the
1775 * process nor do we know its entire history. We only know it
1776 * was tainted so we dump it as root in mode 2.
1778 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1779 flag = O_EXCL; /* Stop rewrite attacks */
1780 cred->fsuid = 0; /* Dump root private */
1783 retval = coredump_wait(exit_code, &core_state);
1789 old_cred = override_creds(cred);
1792 * Clear any false indication of pending signals that might
1793 * be seen by the filesystem code called to write the core file.
1795 clear_thread_flag(TIF_SIGPENDING);
1798 * lock_kernel() because format_corename() is controlled by sysctl, which
1799 * uses lock_kernel()
1802 ispipe = format_corename(corename, signr);
1805 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1806 * to a pipe. Since we're not writing directly to the filesystem
1807 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1808 * created unless the pipe reader choses to write out the core file
1809 * at which point file size limits and permissions will be imposed
1810 * as it does with any other process
1812 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1816 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1818 printk(KERN_WARNING "%s failed to allocate memory\n",
1822 /* Terminate the string before the first option */
1823 delimit = strchr(corename, ' ');
1826 delimit = strrchr(helper_argv[0], '/');
1830 delimit = helper_argv[0];
1831 if (!strcmp(delimit, current->comm)) {
1832 printk(KERN_NOTICE "Recursive core dump detected, "
1837 core_limit = RLIM_INFINITY;
1839 /* SIGPIPE can happen, but it's just never processed */
1840 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1842 printk(KERN_INFO "Core dump to %s pipe failed\n",
1847 file = filp_open(corename,
1848 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1852 inode = file->f_path.dentry->d_inode;
1853 if (inode->i_nlink > 1)
1854 goto close_fail; /* multiple links - don't dump */
1855 if (!ispipe && d_unhashed(file->f_path.dentry))
1858 /* AK: actually i see no reason to not allow this for named pipes etc.,
1859 but keep the previous behaviour for now. */
1860 if (!ispipe && !S_ISREG(inode->i_mode))
1863 * Dont allow local users get cute and trick others to coredump
1864 * into their pre-created files:
1866 if (inode->i_uid != current_fsuid())
1870 if (!file->f_op->write)
1872 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1875 retval = binfmt->core_dump(signr, regs, file, core_limit);
1878 current->signal->group_exit_code |= 0x80;
1880 filp_close(file, NULL);
1883 argv_free(helper_argv);
1885 revert_creds(old_cred);
1887 coredump_finish(mm);