exec.c 45.2 KB
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/*
 *  linux/fs/exec.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * #!-checking implemented by tytso.
 */
/*
 * Demand-loading implemented 01.12.91 - no need to read anything but
 * the header into memory. The inode of the executable is put into
 * "current->executable", and page faults do the actual loading. Clean.
 *
 * Once more I can proudly say that linux stood up to being changed: it
 * was less than 2 hours work to get demand-loading completely implemented.
 *
 * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
 * current->executable is only used by the procfs.  This allows a dispatch
 * table to check for several different types  of binary formats.  We keep
 * trying until we recognize the file or we run out of supported binary
 * formats. 
 */

#include <linux/slab.h>
#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/mm.h>
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#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
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#include <linux/swap.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/pagemap.h>
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#include <linux/perf_event.h>
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#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/key.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/utsname.h>
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#include <linux/pid_namespace.h>
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#include <linux/module.h>
#include <linux/namei.h>
#include <linux/proc_fs.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/audit.h>
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#include <linux/tracehook.h>
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#include <linux/kmod.h>
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#include <linux/fsnotify.h>
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#include <linux/fs_struct.h>
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#include <linux/pipe_fs_i.h>
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#include <asm/uaccess.h>
#include <asm/mmu_context.h>
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#include <asm/tlb.h>
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#include "internal.h"
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int core_uses_pid;
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char core_pattern[CORENAME_MAX_SIZE] = "core";
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unsigned int core_pipe_limit;
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int suid_dumpable = 0;

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/* The maximal length of core_pattern is also specified in sysctl.c */

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static LIST_HEAD(formats);
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static DEFINE_RWLOCK(binfmt_lock);

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int __register_binfmt(struct linux_binfmt * fmt, int insert)
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{
	if (!fmt)
		return -EINVAL;
	write_lock(&binfmt_lock);
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	insert ? list_add(&fmt->lh, &formats) :
		 list_add_tail(&fmt->lh, &formats);
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	write_unlock(&binfmt_lock);
	return 0;	
}

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EXPORT_SYMBOL(__register_binfmt);
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void unregister_binfmt(struct linux_binfmt * fmt)
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{
	write_lock(&binfmt_lock);
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	list_del(&fmt->lh);
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	write_unlock(&binfmt_lock);
}

EXPORT_SYMBOL(unregister_binfmt);

static inline void put_binfmt(struct linux_binfmt * fmt)
{
	module_put(fmt->module);
}

/*
 * Note that a shared library must be both readable and executable due to
 * security reasons.
 *
 * Also note that we take the address to load from from the file itself.
 */
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SYSCALL_DEFINE1(uselib, const char __user *, library)
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{
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	struct file *file;
	char *tmp = getname(library);
	int error = PTR_ERR(tmp);

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	if (IS_ERR(tmp))
		goto out;

	file = do_filp_open(AT_FDCWD, tmp,
				O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
				MAY_READ | MAY_EXEC | MAY_OPEN);
	putname(tmp);
	error = PTR_ERR(file);
	if (IS_ERR(file))
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		goto out;

	error = -EINVAL;
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	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
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		goto exit;

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	error = -EACCES;
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	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
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		goto exit;

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	fsnotify_open(file->f_path.dentry);

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	error = -ENOEXEC;
	if(file->f_op) {
		struct linux_binfmt * fmt;

		read_lock(&binfmt_lock);
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		list_for_each_entry(fmt, &formats, lh) {
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			if (!fmt->load_shlib)
				continue;
			if (!try_module_get(fmt->module))
				continue;
			read_unlock(&binfmt_lock);
			error = fmt->load_shlib(file);
			read_lock(&binfmt_lock);
			put_binfmt(fmt);
			if (error != -ENOEXEC)
				break;
		}
		read_unlock(&binfmt_lock);
	}
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exit:
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	fput(file);
out:
  	return error;
}

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#ifdef CONFIG_MMU

static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
		int write)
{
	struct page *page;
	int ret;

#ifdef CONFIG_STACK_GROWSUP
	if (write) {
		ret = expand_stack_downwards(bprm->vma, pos);
		if (ret < 0)
			return NULL;
	}
#endif
	ret = get_user_pages(current, bprm->mm, pos,
			1, write, 1, &page, NULL);
	if (ret <= 0)
		return NULL;

	if (write) {
		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
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		struct rlimit *rlim;

		/*
		 * We've historically supported up to 32 pages (ARG_MAX)
		 * of argument strings even with small stacks
		 */
		if (size <= ARG_MAX)
			return page;
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		/*
		 * Limit to 1/4-th the stack size for the argv+env strings.
		 * This ensures that:
		 *  - the remaining binfmt code will not run out of stack space,
		 *  - the program will have a reasonable amount of stack left
		 *    to work from.
		 */
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		rlim = current->signal->rlim;
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		if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
			put_page(page);
			return NULL;
		}
	}

	return page;
}

static void put_arg_page(struct page *page)
{
	put_page(page);
}

static void free_arg_page(struct linux_binprm *bprm, int i)
{
}

static void free_arg_pages(struct linux_binprm *bprm)
{
}

static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
		struct page *page)
{
	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
}

static int __bprm_mm_init(struct linux_binprm *bprm)
{
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	int err;
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	struct vm_area_struct *vma = NULL;
	struct mm_struct *mm = bprm->mm;

	bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (!vma)
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		return -ENOMEM;
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	down_write(&mm->mmap_sem);
	vma->vm_mm = mm;

	/*
	 * Place the stack at the largest stack address the architecture
	 * supports. Later, we'll move this to an appropriate place. We don't
	 * use STACK_TOP because that can depend on attributes which aren't
	 * configured yet.
	 */
	vma->vm_end = STACK_TOP_MAX;
	vma->vm_start = vma->vm_end - PAGE_SIZE;
	vma->vm_flags = VM_STACK_FLAGS;
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	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
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	err = insert_vm_struct(mm, vma);
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	if (err)
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		goto err;

	mm->stack_vm = mm->total_vm = 1;
	up_write(&mm->mmap_sem);
	bprm->p = vma->vm_end - sizeof(void *);
	return 0;
err:
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	up_write(&mm->mmap_sem);
	bprm->vma = NULL;
	kmem_cache_free(vm_area_cachep, vma);
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	return err;
}

static bool valid_arg_len(struct linux_binprm *bprm, long len)
{
	return len <= MAX_ARG_STRLEN;
}

#else

static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
		int write)
{
	struct page *page;

	page = bprm->page[pos / PAGE_SIZE];
	if (!page && write) {
		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
		if (!page)
			return NULL;
		bprm->page[pos / PAGE_SIZE] = page;
	}

	return page;
}

static void put_arg_page(struct page *page)
{
}

static void free_arg_page(struct linux_binprm *bprm, int i)
{
	if (bprm->page[i]) {
		__free_page(bprm->page[i]);
		bprm->page[i] = NULL;
	}
}

static void free_arg_pages(struct linux_binprm *bprm)
{
	int i;

	for (i = 0; i < MAX_ARG_PAGES; i++)
		free_arg_page(bprm, i);
}

static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
		struct page *page)
{
}

static int __bprm_mm_init(struct linux_binprm *bprm)
{
	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
	return 0;
}

static bool valid_arg_len(struct linux_binprm *bprm, long len)
{
	return len <= bprm->p;
}

#endif /* CONFIG_MMU */

/*
 * Create a new mm_struct and populate it with a temporary stack
 * vm_area_struct.  We don't have enough context at this point to set the stack
 * flags, permissions, and offset, so we use temporary values.  We'll update
 * them later in setup_arg_pages().
 */
int bprm_mm_init(struct linux_binprm *bprm)
{
	int err;
	struct mm_struct *mm = NULL;

	bprm->mm = mm = mm_alloc();
	err = -ENOMEM;
	if (!mm)
		goto err;

	err = init_new_context(current, mm);
	if (err)
		goto err;

	err = __bprm_mm_init(bprm);
	if (err)
		goto err;

	return 0;

err:
	if (mm) {
		bprm->mm = NULL;
		mmdrop(mm);
	}

	return err;
}

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/*
 * count() counts the number of strings in array ARGV.
 */
static int count(char __user * __user * argv, int max)
{
	int i = 0;

	if (argv != NULL) {
		for (;;) {
			char __user * p;

			if (get_user(p, argv))
				return -EFAULT;
			if (!p)
				break;
			argv++;
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			if (i++ >= max)
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				return -E2BIG;
			cond_resched();
		}
	}
	return i;
}

/*
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 * 'copy_strings()' copies argument/environment strings from the old
 * processes's memory to the new process's stack.  The call to get_user_pages()
 * ensures the destination page is created and not swapped out.
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 */
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static int copy_strings(int argc, char __user * __user * argv,
			struct linux_binprm *bprm)
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{
	struct page *kmapped_page = NULL;
	char *kaddr = NULL;
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	unsigned long kpos = 0;
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	int ret;

	while (argc-- > 0) {
		char __user *str;
		int len;
		unsigned long pos;

		if (get_user(str, argv+argc) ||
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				!(len = strnlen_user(str, MAX_ARG_STRLEN))) {
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			ret = -EFAULT;
			goto out;
		}

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		if (!valid_arg_len(bprm, len)) {
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			ret = -E2BIG;
			goto out;
		}

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		/* We're going to work our way backwords. */
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		pos = bprm->p;
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		str += len;
		bprm->p -= len;
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		while (len > 0) {
			int offset, bytes_to_copy;

			offset = pos % PAGE_SIZE;
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			if (offset == 0)
				offset = PAGE_SIZE;

			bytes_to_copy = offset;
			if (bytes_to_copy > len)
				bytes_to_copy = len;

			offset -= bytes_to_copy;
			pos -= bytes_to_copy;
			str -= bytes_to_copy;
			len -= bytes_to_copy;

			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
				struct page *page;

				page = get_arg_page(bprm, pos, 1);
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				if (!page) {
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					ret = -E2BIG;
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					goto out;
				}

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				if (kmapped_page) {
					flush_kernel_dcache_page(kmapped_page);
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					kunmap(kmapped_page);
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					put_arg_page(kmapped_page);
				}
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				kmapped_page = page;
				kaddr = kmap(kmapped_page);
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				kpos = pos & PAGE_MASK;
				flush_arg_page(bprm, kpos, kmapped_page);
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			}
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			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
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				ret = -EFAULT;
				goto out;
			}
		}
	}
	ret = 0;
out:
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	if (kmapped_page) {
		flush_kernel_dcache_page(kmapped_page);
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		kunmap(kmapped_page);
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		put_arg_page(kmapped_page);
	}
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	return ret;
}

/*
 * Like copy_strings, but get argv and its values from kernel memory.
 */
int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
{
	int r;
	mm_segment_t oldfs = get_fs();
	set_fs(KERNEL_DS);
	r = copy_strings(argc, (char __user * __user *)argv, bprm);
	set_fs(oldfs);
	return r;
}
EXPORT_SYMBOL(copy_strings_kernel);

#ifdef CONFIG_MMU
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/*
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 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
 * the binfmt code determines where the new stack should reside, we shift it to
 * its final location.  The process proceeds as follows:
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 *
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 * 1) Use shift to calculate the new vma endpoints.
 * 2) Extend vma to cover both the old and new ranges.  This ensures the
 *    arguments passed to subsequent functions are consistent.
 * 3) Move vma's page tables to the new range.
 * 4) Free up any cleared pgd range.
 * 5) Shrink the vma to cover only the new range.
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 */
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static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
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{
	struct mm_struct *mm = vma->vm_mm;
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	unsigned long old_start = vma->vm_start;
	unsigned long old_end = vma->vm_end;
	unsigned long length = old_end - old_start;
	unsigned long new_start = old_start - shift;
	unsigned long new_end = old_end - shift;
	struct mmu_gather *tlb;
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	BUG_ON(new_start > new_end);
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	/*
	 * ensure there are no vmas between where we want to go
	 * and where we are
	 */
	if (vma != find_vma(mm, new_start))
		return -EFAULT;

	/*
	 * cover the whole range: [new_start, old_end)
	 */
	vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);

	/*
	 * move the page tables downwards, on failure we rely on
	 * process cleanup to remove whatever mess we made.
	 */
	if (length != move_page_tables(vma, old_start,
				       vma, new_start, length))
		return -ENOMEM;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
	if (new_end > old_start) {
		/*
		 * when the old and new regions overlap clear from new_end.
		 */
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		free_pgd_range(tlb, new_end, old_end, new_end,
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			vma->vm_next ? vma->vm_next->vm_start : 0);
	} else {
		/*
		 * otherwise, clean from old_start; this is done to not touch
		 * the address space in [new_end, old_start) some architectures
		 * have constraints on va-space that make this illegal (IA64) -
		 * for the others its just a little faster.
		 */
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		free_pgd_range(tlb, old_start, old_end, new_end,
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			vma->vm_next ? vma->vm_next->vm_start : 0);
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	}
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	tlb_finish_mmu(tlb, new_end, old_end);

	/*
	 * shrink the vma to just the new range.
	 */
	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);

	return 0;
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}

#define EXTRA_STACK_VM_PAGES	20	/* random */

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/*
 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 * the stack is optionally relocated, and some extra space is added.
 */
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int setup_arg_pages(struct linux_binprm *bprm,
		    unsigned long stack_top,
		    int executable_stack)
{
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	unsigned long ret;
	unsigned long stack_shift;
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	struct mm_struct *mm = current->mm;
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	struct vm_area_struct *vma = bprm->vma;
	struct vm_area_struct *prev = NULL;
	unsigned long vm_flags;
	unsigned long stack_base;
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	unsigned long stack_size;
	unsigned long stack_expand;
	unsigned long rlim_stack;
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#ifdef CONFIG_STACK_GROWSUP
	/* Limit stack size to 1GB */
	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
	if (stack_base > (1 << 30))
		stack_base = 1 << 30;

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	/* Make sure we didn't let the argument array grow too large. */
	if (vma->vm_end - vma->vm_start > stack_base)
		return -ENOMEM;
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	stack_base = PAGE_ALIGN(stack_top - stack_base);
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	stack_shift = vma->vm_start - stack_base;
	mm->arg_start = bprm->p - stack_shift;
	bprm->p = vma->vm_end - stack_shift;
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#else
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	stack_top = arch_align_stack(stack_top);
	stack_top = PAGE_ALIGN(stack_top);
	stack_shift = vma->vm_end - stack_top;

	bprm->p -= stack_shift;
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	mm->arg_start = bprm->p;
#endif

	if (bprm->loader)
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		bprm->loader -= stack_shift;
	bprm->exec -= stack_shift;
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	down_write(&mm->mmap_sem);
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	vm_flags = VM_STACK_FLAGS;
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	/*
	 * Adjust stack execute permissions; explicitly enable for
	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
	 * (arch default) otherwise.
	 */
	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
		vm_flags |= VM_EXEC;
	else if (executable_stack == EXSTACK_DISABLE_X)
		vm_flags &= ~VM_EXEC;
	vm_flags |= mm->def_flags;

	ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
			vm_flags);
	if (ret)
		goto out_unlock;
	BUG_ON(prev != vma);

	/* Move stack pages down in memory. */
	if (stack_shift) {
		ret = shift_arg_pages(vma, stack_shift);
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		if (ret)
			goto out_unlock;
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	}

633 634 635 636 637 638 639
	stack_expand = EXTRA_STACK_VM_PAGES * PAGE_SIZE;
	stack_size = vma->vm_end - vma->vm_start;
	/*
	 * Align this down to a page boundary as expand_stack
	 * will align it up.
	 */
	rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
640
#ifdef CONFIG_STACK_GROWSUP
641 642 643 644
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_start + rlim_stack;
	else
		stack_base = vma->vm_end + stack_expand;
645
#else
646 647 648 649
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_end - rlim_stack;
	else
		stack_base = vma->vm_start - stack_expand;
650 651 652 653 654 655
#endif
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
L
Linus Torvalds 已提交
656
	up_write(&mm->mmap_sem);
657
	return ret;
L
Linus Torvalds 已提交
658 659 660 661 662 663 664 665
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct file *file;
666
	int err;
L
Linus Torvalds 已提交
667

668 669 670 671
	file = do_filp_open(AT_FDCWD, name,
				O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
				MAY_EXEC | MAY_OPEN);
	if (IS_ERR(file))
672 673 674
		goto out;

	err = -EACCES;
675 676
	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
		goto exit;
677

678 679
	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
		goto exit;
680

681 682
	fsnotify_open(file->f_path.dentry);

683
	err = deny_write_access(file);
684 685
	if (err)
		goto exit;
L
Linus Torvalds 已提交
686

687
out:
688 689
	return file;

690 691
exit:
	fput(file);
692 693
	return ERR_PTR(err);
}
L
Linus Torvalds 已提交
694 695
EXPORT_SYMBOL(open_exec);

M
Mimi Zohar 已提交
696 697
int kernel_read(struct file *file, loff_t offset,
		char *addr, unsigned long count)
L
Linus Torvalds 已提交
698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720
{
	mm_segment_t old_fs;
	loff_t pos = offset;
	int result;

	old_fs = get_fs();
	set_fs(get_ds());
	/* The cast to a user pointer is valid due to the set_fs() */
	result = vfs_read(file, (void __user *)addr, count, &pos);
	set_fs(old_fs);
	return result;
}

EXPORT_SYMBOL(kernel_read);

static int exec_mmap(struct mm_struct *mm)
{
	struct task_struct *tsk;
	struct mm_struct * old_mm, *active_mm;

	/* Notify parent that we're no longer interested in the old VM */
	tsk = current;
	old_mm = current->mm;
721
	sync_mm_rss(tsk, old_mm);
L
Linus Torvalds 已提交
722 723 724 725 726 727 728
	mm_release(tsk, old_mm);

	if (old_mm) {
		/*
		 * Make sure that if there is a core dump in progress
		 * for the old mm, we get out and die instead of going
		 * through with the exec.  We must hold mmap_sem around
729
		 * checking core_state and changing tsk->mm.
L
Linus Torvalds 已提交
730 731
		 */
		down_read(&old_mm->mmap_sem);
732
		if (unlikely(old_mm->core_state)) {
L
Linus Torvalds 已提交
733 734 735 736 737 738 739 740 741 742 743 744 745
			up_read(&old_mm->mmap_sem);
			return -EINTR;
		}
	}
	task_lock(tsk);
	active_mm = tsk->active_mm;
	tsk->mm = mm;
	tsk->active_mm = mm;
	activate_mm(active_mm, mm);
	task_unlock(tsk);
	arch_pick_mmap_layout(mm);
	if (old_mm) {
		up_read(&old_mm->mmap_sem);
746
		BUG_ON(active_mm != old_mm);
747
		mm_update_next_owner(old_mm);
L
Linus Torvalds 已提交
748 749 750 751 752 753 754 755 756 757 758 759 760
		mmput(old_mm);
		return 0;
	}
	mmdrop(active_mm);
	return 0;
}

/*
 * This function makes sure the current process has its own signal table,
 * so that flush_signal_handlers can later reset the handlers without
 * disturbing other processes.  (Other processes might share the signal
 * table via the CLONE_SIGHAND option to clone().)
 */
761
static int de_thread(struct task_struct *tsk)
L
Linus Torvalds 已提交
762 763
{
	struct signal_struct *sig = tsk->signal;
764
	struct sighand_struct *oldsighand = tsk->sighand;
L
Linus Torvalds 已提交
765 766 767
	spinlock_t *lock = &oldsighand->siglock;
	int count;

768
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
769 770 771 772 773 774
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
775
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
776 777 778 779 780 781 782
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
783
	sig->group_exit_task = tsk;
784
	zap_other_threads(tsk);
L
Linus Torvalds 已提交
785

786 787
	/* Account for the thread group leader hanging around: */
	count = thread_group_leader(tsk) ? 1 : 2;
788
	sig->notify_count = count;
L
Linus Torvalds 已提交
789 790 791 792 793 794 795 796 797 798 799 800 801
	while (atomic_read(&sig->count) > count) {
		__set_current_state(TASK_UNINTERRUPTIBLE);
		spin_unlock_irq(lock);
		schedule();
		spin_lock_irq(lock);
	}
	spin_unlock_irq(lock);

	/*
	 * At this point all other threads have exited, all we have to
	 * do is to wait for the thread group leader to become inactive,
	 * and to assume its PID:
	 */
802
	if (!thread_group_leader(tsk)) {
803
		struct task_struct *leader = tsk->group_leader;
804

805
		sig->notify_count = -1;	/* for exit_notify() */
806 807 808 809 810 811 812 813
		for (;;) {
			write_lock_irq(&tasklist_lock);
			if (likely(leader->exit_state))
				break;
			__set_current_state(TASK_UNINTERRUPTIBLE);
			write_unlock_irq(&tasklist_lock);
			schedule();
		}
L
Linus Torvalds 已提交
814

815 816 817 818 819 820 821 822 823 824
		/*
		 * The only record we have of the real-time age of a
		 * process, regardless of execs it's done, is start_time.
		 * All the past CPU time is accumulated in signal_struct
		 * from sister threads now dead.  But in this non-leader
		 * exec, nothing survives from the original leader thread,
		 * whose birth marks the true age of this process now.
		 * When we take on its identity by switching to its PID, we
		 * also take its birthdate (always earlier than our own).
		 */
825
		tsk->start_time = leader->start_time;
826

827 828
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
829 830 831 832 833 834
		/*
		 * An exec() starts a new thread group with the
		 * TGID of the previous thread group. Rehash the
		 * two threads with a switched PID, and release
		 * the former thread group leader:
		 */
835 836

		/* Become a process group leader with the old leader's pid.
837 838
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
839 840
		 *       is called.  Odd but simple and correct.
		 */
841 842
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
843
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
844 845
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
846

847
		list_replace_rcu(&leader->tasks, &tsk->tasks);
848
		list_replace_init(&leader->sibling, &tsk->sibling);
L
Linus Torvalds 已提交
849

850 851
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
852

853
		tsk->exit_signal = SIGCHLD;
854 855 856

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
857
		write_unlock_irq(&tasklist_lock);
858 859

		release_task(leader);
860
	}
L
Linus Torvalds 已提交
861

862 863
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
864 865

no_thread_group:
J
Jiri Pirko 已提交
866 867 868
	if (current->mm)
		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);

L
Linus Torvalds 已提交
869
	exit_itimers(sig);
870
	flush_itimer_signals();
871

872 873
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
874
		/*
875 876
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
877
		 */
878 879 880 881
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
882 883 884 885 886 887
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
888
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
889 890 891
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

892
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
893 894
	}

895
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
896 897
	return 0;
}
O
Oleg Nesterov 已提交
898

L
Linus Torvalds 已提交
899 900 901 902
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
903
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
904 905
{
	long j = -1;
906
	struct fdtable *fdt;
L
Linus Torvalds 已提交
907 908 909 910 911 912 913

	spin_lock(&files->file_lock);
	for (;;) {
		unsigned long set, i;

		j++;
		i = j * __NFDBITS;
914
		fdt = files_fdtable(files);
915
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
916
			break;
917
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
918 919
		if (!set)
			continue;
920
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
921 922 923 924 925 926 927 928 929 930 931 932
		spin_unlock(&files->file_lock);
		for ( ; set ; i++,set >>= 1) {
			if (set & 1) {
				sys_close(i);
			}
		}
		spin_lock(&files->file_lock);

	}
	spin_unlock(&files->file_lock);
}

933
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
934 935 936 937 938
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
939
	return buf;
L
Linus Torvalds 已提交
940 941 942 943 944
}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
945 946 947 948 949 950 951 952 953

	/*
	 * Threads may access current->comm without holding
	 * the task lock, so write the string carefully.
	 * Readers without a lock may see incomplete new
	 * names but are safe from non-terminating string reads.
	 */
	memset(tsk->comm, 0, TASK_COMM_LEN);
	wmb();
L
Linus Torvalds 已提交
954 955
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
956
	perf_event_comm(tsk);
L
Linus Torvalds 已提交
957 958 959 960
}

int flush_old_exec(struct linux_binprm * bprm)
{
961
	int retval;
L
Linus Torvalds 已提交
962 963 964 965 966 967 968 969 970

	/*
	 * Make sure we have a private signal table and that
	 * we are unassociated from the previous thread group.
	 */
	retval = de_thread(current);
	if (retval)
		goto out;

M
Matt Helsley 已提交
971 972
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
973 974 975 976 977
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
978
		goto out;
L
Linus Torvalds 已提交
979 980

	bprm->mm = NULL;		/* We're using it now */
981 982 983 984 985

	current->flags &= ~PF_RANDOMIZE;
	flush_thread();
	current->personality &= ~bprm->per_clear;

986 987 988 989 990 991 992 993 994 995 996 997 998 999
	return 0;

out:
	return retval;
}
EXPORT_SYMBOL(flush_old_exec);

void setup_new_exec(struct linux_binprm * bprm)
{
	int i, ch;
	char * name;
	char tcomm[sizeof(current->comm)];

	arch_pick_mmap_layout(current->mm);
L
Linus Torvalds 已提交
1000 1001 1002 1003

	/* This is the point of no return */
	current->sas_ss_sp = current->sas_ss_size = 0;

1004
	if (current_euid() == current_uid() && current_egid() == current_gid())
1005
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
1006
	else
1007
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
1008

L
Linus Torvalds 已提交
1009
	name = bprm->filename;
1010 1011

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
1012 1013
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
1014
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
1015 1016 1017 1018 1019 1020 1021
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

1022 1023 1024 1025 1026 1027
	/* Set the new mm task size. We have to do that late because it may
	 * depend on TIF_32BIT which is only updated in flush_thread() on
	 * some architectures like powerpc
	 */
	current->mm->task_size = TASK_SIZE;

1028 1029 1030
	/* install the new credentials */
	if (bprm->cred->uid != current_euid() ||
	    bprm->cred->gid != current_egid()) {
1031 1032
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
1033
		   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1034
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1035 1036
	}

I
Ingo Molnar 已提交
1037 1038 1039 1040 1041
	/*
	 * Flush performance counters when crossing a
	 * security domain:
	 */
	if (!get_dumpable(current->mm))
1042
		perf_event_exit_task(current);
I
Ingo Molnar 已提交
1043

L
Linus Torvalds 已提交
1044 1045 1046 1047 1048 1049 1050 1051
	/* An exec changes our domain. We are no longer part of the thread
	   group */

	current->self_exec_id++;
			
	flush_signal_handlers(current, 0);
	flush_old_files(current->files);
}
1052
EXPORT_SYMBOL(setup_new_exec);
L
Linus Torvalds 已提交
1053

1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
/*
 * Prepare credentials and lock ->cred_guard_mutex.
 * install_exec_creds() commits the new creds and drops the lock.
 * Or, if exec fails before, free_bprm() should release ->cred and
 * and unlock.
 */
int prepare_bprm_creds(struct linux_binprm *bprm)
{
	if (mutex_lock_interruptible(&current->cred_guard_mutex))
		return -ERESTARTNOINTR;

	bprm->cred = prepare_exec_creds();
	if (likely(bprm->cred))
		return 0;

	mutex_unlock(&current->cred_guard_mutex);
	return -ENOMEM;
}

void free_bprm(struct linux_binprm *bprm)
{
	free_arg_pages(bprm);
	if (bprm->cred) {
		mutex_unlock(&current->cred_guard_mutex);
		abort_creds(bprm->cred);
	}
	kfree(bprm);
}

1083 1084 1085 1086 1087 1088 1089 1090 1091
/*
 * install the new credentials for this executable
 */
void install_exec_creds(struct linux_binprm *bprm)
{
	security_bprm_committing_creds(bprm);

	commit_creds(bprm->cred);
	bprm->cred = NULL;
1092 1093
	/*
	 * cred_guard_mutex must be held at least to this point to prevent
1094
	 * ptrace_attach() from altering our determination of the task's
1095 1096
	 * credentials; any time after this it may be unlocked.
	 */
1097
	security_bprm_committed_creds(bprm);
1098
	mutex_unlock(&current->cred_guard_mutex);
1099 1100 1101 1102 1103
}
EXPORT_SYMBOL(install_exec_creds);

/*
 * determine how safe it is to execute the proposed program
1104
 * - the caller must hold current->cred_guard_mutex to protect against
1105 1106
 *   PTRACE_ATTACH
 */
A
Al Viro 已提交
1107
int check_unsafe_exec(struct linux_binprm *bprm)
1108
{
D
David Howells 已提交
1109
	struct task_struct *p = current, *t;
1110
	unsigned n_fs;
A
Al Viro 已提交
1111
	int res = 0;
1112 1113 1114

	bprm->unsafe = tracehook_unsafe_exec(p);

D
David Howells 已提交
1115
	n_fs = 1;
A
Al Viro 已提交
1116
	write_lock(&p->fs->lock);
1117
	rcu_read_lock();
D
David Howells 已提交
1118 1119 1120 1121
	for (t = next_thread(p); t != p; t = next_thread(t)) {
		if (t->fs == p->fs)
			n_fs++;
	}
1122
	rcu_read_unlock();
D
David Howells 已提交
1123

1124
	if (p->fs->users > n_fs) {
1125
		bprm->unsafe |= LSM_UNSAFE_SHARE;
A
Al Viro 已提交
1126
	} else {
1127 1128 1129 1130 1131
		res = -EAGAIN;
		if (!p->fs->in_exec) {
			p->fs->in_exec = 1;
			res = 1;
		}
A
Al Viro 已提交
1132 1133 1134 1135
	}
	write_unlock(&p->fs->lock);

	return res;
1136 1137
}

L
Linus Torvalds 已提交
1138 1139 1140
/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1141 1142
 *
 * This may be called multiple times for binary chains (scripts for example).
L
Linus Torvalds 已提交
1143 1144 1145
 */
int prepare_binprm(struct linux_binprm *bprm)
{
1146
	umode_t mode;
1147
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1148 1149 1150 1151 1152 1153
	int retval;

	mode = inode->i_mode;
	if (bprm->file->f_op == NULL)
		return -EACCES;

1154 1155 1156
	/* clear any previous set[ug]id data from a previous binary */
	bprm->cred->euid = current_euid();
	bprm->cred->egid = current_egid();
L
Linus Torvalds 已提交
1157

1158
	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1159 1160
		/* Set-uid? */
		if (mode & S_ISUID) {
1161 1162
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->euid = inode->i_uid;
L
Linus Torvalds 已提交
1163 1164 1165 1166 1167 1168 1169 1170 1171
		}

		/* Set-gid? */
		/*
		 * If setgid is set but no group execute bit then this
		 * is a candidate for mandatory locking, not a setgid
		 * executable.
		 */
		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1172 1173
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->egid = inode->i_gid;
L
Linus Torvalds 已提交
1174 1175 1176 1177
		}
	}

	/* fill in binprm security blob */
1178
	retval = security_bprm_set_creds(bprm);
L
Linus Torvalds 已提交
1179 1180
	if (retval)
		return retval;
1181
	bprm->cred_prepared = 1;
L
Linus Torvalds 已提交
1182

1183 1184
	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
L
Linus Torvalds 已提交
1185 1186 1187 1188
}

EXPORT_SYMBOL(prepare_binprm);

N
Nick Piggin 已提交
1189 1190 1191 1192 1193
/*
 * Arguments are '\0' separated strings found at the location bprm->p
 * points to; chop off the first by relocating brpm->p to right after
 * the first '\0' encountered.
 */
1194
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1195
{
1196 1197 1198 1199
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1200

1201 1202
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1203

1204 1205 1206 1207 1208 1209 1210 1211
	do {
		offset = bprm->p & ~PAGE_MASK;
		page = get_arg_page(bprm, bprm->p, 0);
		if (!page) {
			ret = -EFAULT;
			goto out;
		}
		kaddr = kmap_atomic(page, KM_USER0);
N
Nick Piggin 已提交
1212

1213 1214 1215
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1216

1217 1218
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1219

1220 1221 1222
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1223

1224 1225 1226
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1227

1228 1229
out:
	return ret;
L
Linus Torvalds 已提交
1230 1231 1232 1233 1234 1235 1236 1237
}
EXPORT_SYMBOL(remove_arg_zero);

/*
 * cycle the list of binary formats handler, until one recognizes the image
 */
int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
{
1238
	unsigned int depth = bprm->recursion_depth;
L
Linus Torvalds 已提交
1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
	int try,retval;
	struct linux_binfmt *fmt;

	retval = security_bprm_check(bprm);
	if (retval)
		return retval;

	/* kernel module loader fixup */
	/* so we don't try to load run modprobe in kernel space. */
	set_fs(USER_DS);
A
Al Viro 已提交
1249 1250 1251 1252 1253

	retval = audit_bprm(bprm);
	if (retval)
		return retval;

L
Linus Torvalds 已提交
1254 1255 1256
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1257
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1258 1259 1260 1261 1262 1263 1264
			int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
			if (!fn)
				continue;
			if (!try_module_get(fmt->module))
				continue;
			read_unlock(&binfmt_lock);
			retval = fn(bprm, regs);
1265 1266 1267 1268 1269 1270
			/*
			 * Restore the depth counter to its starting value
			 * in this call, so we don't have to rely on every
			 * load_binary function to restore it on return.
			 */
			bprm->recursion_depth = depth;
L
Linus Torvalds 已提交
1271
			if (retval >= 0) {
1272 1273
				if (depth == 0)
					tracehook_report_exec(fmt, bprm, regs);
L
Linus Torvalds 已提交
1274 1275 1276 1277 1278 1279
				put_binfmt(fmt);
				allow_write_access(bprm->file);
				if (bprm->file)
					fput(bprm->file);
				bprm->file = NULL;
				current->did_exec = 1;
M
Matt Helsley 已提交
1280
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294
				return retval;
			}
			read_lock(&binfmt_lock);
			put_binfmt(fmt);
			if (retval != -ENOEXEC || bprm->mm == NULL)
				break;
			if (!bprm->file) {
				read_unlock(&binfmt_lock);
				return retval;
			}
		}
		read_unlock(&binfmt_lock);
		if (retval != -ENOEXEC || bprm->mm == NULL) {
			break;
J
Johannes Berg 已提交
1295 1296
#ifdef CONFIG_MODULES
		} else {
L
Linus Torvalds 已提交
1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
			if (printable(bprm->buf[0]) &&
			    printable(bprm->buf[1]) &&
			    printable(bprm->buf[2]) &&
			    printable(bprm->buf[3]))
				break; /* -ENOEXEC */
			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
#endif
		}
	}
	return retval;
}

EXPORT_SYMBOL(search_binary_handler);

/*
 * sys_execve() executes a new program.
 */
int do_execve(char * filename,
	char __user *__user *argv,
	char __user *__user *envp,
	struct pt_regs * regs)
{
	struct linux_binprm *bprm;
	struct file *file;
1322
	struct files_struct *displaced;
1323
	bool clear_in_exec;
L
Linus Torvalds 已提交
1324 1325
	int retval;

1326
	retval = unshare_files(&displaced);
1327 1328 1329
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1330
	retval = -ENOMEM;
1331
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1332
	if (!bprm)
1333
		goto out_files;
L
Linus Torvalds 已提交
1334

1335 1336
	retval = prepare_bprm_creds(bprm);
	if (retval)
1337
		goto out_free;
A
Al Viro 已提交
1338 1339

	retval = check_unsafe_exec(bprm);
1340
	if (retval < 0)
1341
		goto out_free;
1342
	clear_in_exec = retval;
1343
	current->in_execve = 1;
1344

L
Linus Torvalds 已提交
1345 1346 1347
	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
A
Al Viro 已提交
1348
		goto out_unmark;
L
Linus Torvalds 已提交
1349 1350 1351 1352 1353 1354 1355

	sched_exec();

	bprm->file = file;
	bprm->filename = filename;
	bprm->interp = filename;

1356 1357 1358
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1359

1360
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1361
	if ((retval = bprm->argc) < 0)
1362
		goto out;
L
Linus Torvalds 已提交
1363

1364
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384
	if ((retval = bprm->envc) < 0)
		goto out;

	retval = prepare_binprm(bprm);
	if (retval < 0)
		goto out;

	retval = copy_strings_kernel(1, &bprm->filename, bprm);
	if (retval < 0)
		goto out;

	bprm->exec = bprm->p;
	retval = copy_strings(bprm->envc, envp, bprm);
	if (retval < 0)
		goto out;

	retval = copy_strings(bprm->argc, argv, bprm);
	if (retval < 0)
		goto out;

O
Oleg Nesterov 已提交
1385
	current->flags &= ~PF_KTHREAD;
L
Linus Torvalds 已提交
1386
	retval = search_binary_handler(bprm,regs);
1387 1388
	if (retval < 0)
		goto out;
L
Linus Torvalds 已提交
1389

1390 1391
	current->stack_start = current->mm->start_stack;

1392
	/* execve succeeded */
A
Al Viro 已提交
1393
	current->fs->in_exec = 0;
1394
	current->in_execve = 0;
1395 1396 1397 1398 1399
	acct_update_integrals(current);
	free_bprm(bprm);
	if (displaced)
		put_files_struct(displaced);
	return retval;
L
Linus Torvalds 已提交
1400

1401
out:
L
Linus Torvalds 已提交
1402
	if (bprm->mm)
1403
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1404 1405 1406 1407 1408 1409

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
1410

A
Al Viro 已提交
1411
out_unmark:
1412 1413
	if (clear_in_exec)
		current->fs->in_exec = 0;
1414
	current->in_execve = 0;
1415 1416

out_free:
1417
	free_bprm(bprm);
L
Linus Torvalds 已提交
1418

1419
out_files:
1420 1421
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1422 1423 1424 1425
out_ret:
	return retval;
}

1426
void set_binfmt(struct linux_binfmt *new)
L
Linus Torvalds 已提交
1427
{
1428 1429 1430 1431
	struct mm_struct *mm = current->mm;

	if (mm->binfmt)
		module_put(mm->binfmt->module);
L
Linus Torvalds 已提交
1432

1433
	mm->binfmt = new;
1434 1435
	if (new)
		__module_get(new->module);
L
Linus Torvalds 已提交
1436 1437 1438 1439 1440 1441 1442 1443
}

EXPORT_SYMBOL(set_binfmt);

/* format_corename will inspect the pattern parameter, and output a
 * name into corename, which must have space for at least
 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 */
1444
static int format_corename(char *corename, long signr)
L
Linus Torvalds 已提交
1445
{
1446
	const struct cred *cred = current_cred();
1447 1448
	const char *pat_ptr = core_pattern;
	int ispipe = (*pat_ptr == '|');
L
Linus Torvalds 已提交
1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474
	char *out_ptr = corename;
	char *const out_end = corename + CORENAME_MAX_SIZE;
	int rc;
	int pid_in_pattern = 0;

	/* Repeat as long as we have more pattern to process and more output
	   space */
	while (*pat_ptr) {
		if (*pat_ptr != '%') {
			if (out_ptr == out_end)
				goto out;
			*out_ptr++ = *pat_ptr++;
		} else {
			switch (*++pat_ptr) {
			case 0:
				goto out;
			/* Double percent, output one percent */
			case '%':
				if (out_ptr == out_end)
					goto out;
				*out_ptr++ = '%';
				break;
			/* pid */
			case 'p':
				pid_in_pattern = 1;
				rc = snprintf(out_ptr, out_end - out_ptr,
1475
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1476 1477 1478 1479 1480 1481 1482
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
1483
					      "%d", cred->uid);
L
Linus Torvalds 已提交
1484 1485 1486 1487 1488 1489 1490
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
1491
					      "%d", cred->gid);
L
Linus Torvalds 已提交
1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* signal that caused the coredump */
			case 's':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%ld", signr);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* UNIX time of coredump */
			case 't': {
				struct timeval tv;
				do_gettimeofday(&tv);
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%lu", tv.tv_sec);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			}
			/* hostname */
			case 'h':
				down_read(&uts_sem);
				rc = snprintf(out_ptr, out_end - out_ptr,
1519
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532
				up_read(&uts_sem);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* executable */
			case 'e':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%s", current->comm);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
1533 1534 1535 1536 1537 1538 1539 1540
			/* core limit size */
			case 'c':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
L
Linus Torvalds 已提交
1541 1542 1543 1544 1545 1546 1547 1548 1549 1550
			default:
				break;
			}
			++pat_ptr;
		}
	}
	/* Backward compatibility with core_uses_pid:
	 *
	 * If core_pattern does not include a %p (as is the default)
	 * and core_uses_pid is set, then .%pid will be appended to
1551
	 * the filename. Do not do this for piped commands. */
1552
	if (!ispipe && !pid_in_pattern && core_uses_pid) {
L
Linus Torvalds 已提交
1553
		rc = snprintf(out_ptr, out_end - out_ptr,
1554
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1555 1556 1557 1558
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1559
out:
L
Linus Torvalds 已提交
1560
	*out_ptr = 0;
1561
	return ispipe;
L
Linus Torvalds 已提交
1562 1563
}

1564
static int zap_process(struct task_struct *start)
1565 1566
{
	struct task_struct *t;
1567
	int nr = 0;
1568

1569 1570
	start->signal->flags = SIGNAL_GROUP_EXIT;
	start->signal->group_stop_count = 0;
1571 1572 1573 1574

	t = start;
	do {
		if (t != current && t->mm) {
1575 1576
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1577
			nr++;
1578
		}
1579
	} while_each_thread(start, t);
1580 1581

	return nr;
1582 1583
}

1584
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1585
				struct core_state *core_state, int exit_code)
L
Linus Torvalds 已提交
1586 1587
{
	struct task_struct *g, *p;
1588
	unsigned long flags;
1589
	int nr = -EAGAIN;
1590 1591

	spin_lock_irq(&tsk->sighand->siglock);
1592
	if (!signal_group_exit(tsk->signal)) {
1593
		mm->core_state = core_state;
1594
		tsk->signal->group_exit_code = exit_code;
1595
		nr = zap_process(tsk);
L
Linus Torvalds 已提交
1596
	}
1597
	spin_unlock_irq(&tsk->sighand->siglock);
1598 1599
	if (unlikely(nr < 0))
		return nr;
L
Linus Torvalds 已提交
1600

1601
	if (atomic_read(&mm->mm_users) == nr + 1)
1602
		goto done;
1603 1604
	/*
	 * We should find and kill all tasks which use this mm, and we should
1605
	 * count them correctly into ->nr_threads. We don't take tasklist
1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632
	 * lock, but this is safe wrt:
	 *
	 * fork:
	 *	None of sub-threads can fork after zap_process(leader). All
	 *	processes which were created before this point should be
	 *	visible to zap_threads() because copy_process() adds the new
	 *	process to the tail of init_task.tasks list, and lock/unlock
	 *	of ->siglock provides a memory barrier.
	 *
	 * do_exit:
	 *	The caller holds mm->mmap_sem. This means that the task which
	 *	uses this mm can't pass exit_mm(), so it can't exit or clear
	 *	its ->mm.
	 *
	 * de_thread:
	 *	It does list_replace_rcu(&leader->tasks, &current->tasks),
	 *	we must see either old or new leader, this does not matter.
	 *	However, it can change p->sighand, so lock_task_sighand(p)
	 *	must be used. Since p->mm != NULL and we hold ->mmap_sem
	 *	it can't fail.
	 *
	 *	Note also that "g" can be the old leader with ->mm == NULL
	 *	and already unhashed and thus removed from ->thread_group.
	 *	This is OK, __unhash_process()->list_del_rcu() does not
	 *	clear the ->next pointer, we will find the new leader via
	 *	next_thread().
	 */
1633
	rcu_read_lock();
1634
	for_each_process(g) {
1635 1636
		if (g == tsk->group_leader)
			continue;
1637 1638
		if (g->flags & PF_KTHREAD)
			continue;
1639 1640 1641
		p = g;
		do {
			if (p->mm) {
1642
				if (unlikely(p->mm == mm)) {
1643
					lock_task_sighand(p, &flags);
1644
					nr += zap_process(p);
1645 1646
					unlock_task_sighand(p, &flags);
				}
1647 1648
				break;
			}
1649
		} while_each_thread(g, p);
1650
	}
1651
	rcu_read_unlock();
1652
done:
1653
	atomic_set(&core_state->nr_threads, nr);
1654
	return nr;
L
Linus Torvalds 已提交
1655 1656
}

1657
static int coredump_wait(int exit_code, struct core_state *core_state)
L
Linus Torvalds 已提交
1658
{
1659 1660 1661
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion *vfork_done;
O
Oleg Nesterov 已提交
1662
	int core_waiters;
L
Linus Torvalds 已提交
1663

1664
	init_completion(&core_state->startup);
1665 1666
	core_state->dumper.task = tsk;
	core_state->dumper.next = NULL;
1667
	core_waiters = zap_threads(tsk, mm, core_state, exit_code);
O
Oleg Nesterov 已提交
1668 1669
	up_write(&mm->mmap_sem);

1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682
	if (unlikely(core_waiters < 0))
		goto fail;

	/*
	 * Make sure nobody is waiting for us to release the VM,
	 * otherwise we can deadlock when we wait on each other
	 */
	vfork_done = tsk->vfork_done;
	if (vfork_done) {
		tsk->vfork_done = NULL;
		complete(vfork_done);
	}

O
Oleg Nesterov 已提交
1683
	if (core_waiters)
1684
		wait_for_completion(&core_state->startup);
1685 1686
fail:
	return core_waiters;
L
Linus Torvalds 已提交
1687 1688
}

O
Oleg Nesterov 已提交
1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709
static void coredump_finish(struct mm_struct *mm)
{
	struct core_thread *curr, *next;
	struct task_struct *task;

	next = mm->core_state->dumper.next;
	while ((curr = next) != NULL) {
		next = curr->next;
		task = curr->task;
		/*
		 * see exit_mm(), curr->task must not see
		 * ->task == NULL before we read ->next.
		 */
		smp_mb();
		curr->task = NULL;
		wake_up_process(task);
	}

	mm->core_state = NULL;
}

1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758
/*
 * set_dumpable converts traditional three-value dumpable to two flags and
 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
 * these bits are not changed atomically.  So get_dumpable can observe the
 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
 * return either old dumpable or new one by paying attention to the order of
 * modifying the bits.
 *
 * dumpable |   mm->flags (binary)
 * old  new | initial interim  final
 * ---------+-----------------------
 *  0    1  |   00      01      01
 *  0    2  |   00      10(*)   11
 *  1    0  |   01      00      00
 *  1    2  |   01      11      11
 *  2    0  |   11      10(*)   00
 *  2    1  |   11      11      01
 *
 * (*) get_dumpable regards interim value of 10 as 11.
 */
void set_dumpable(struct mm_struct *mm, int value)
{
	switch (value) {
	case 0:
		clear_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 1:
		set_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 2:
		set_bit(MMF_DUMP_SECURELY, &mm->flags);
		smp_wmb();
		set_bit(MMF_DUMPABLE, &mm->flags);
		break;
	}
}

int get_dumpable(struct mm_struct *mm)
{
	int ret;

	ret = mm->flags & 0x3;
	return (ret >= 2) ? 2 : ret;
}

1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781
static void wait_for_dump_helpers(struct file *file)
{
	struct pipe_inode_info *pipe;

	pipe = file->f_path.dentry->d_inode->i_pipe;

	pipe_lock(pipe);
	pipe->readers++;
	pipe->writers--;

	while ((pipe->readers > 1) && (!signal_pending(current))) {
		wake_up_interruptible_sync(&pipe->wait);
		kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
		pipe_wait(pipe);
	}

	pipe->readers--;
	pipe->writers++;
	pipe_unlock(pipe);

}


W
WANG Cong 已提交
1782
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
L
Linus Torvalds 已提交
1783
{
1784
	struct core_state core_state;
L
Linus Torvalds 已提交
1785 1786 1787 1788
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
	struct inode * inode;
D
David Howells 已提交
1789 1790
	const struct cred *old_cred;
	struct cred *cred;
L
Linus Torvalds 已提交
1791
	int retval = 0;
A
Alan Cox 已提交
1792
	int flag = 0;
1793
	int ispipe = 0;
1794 1795
	char **helper_argv = NULL;
	int helper_argc = 0;
1796 1797
	int dump_count = 0;
	static atomic_t core_dump_count = ATOMIC_INIT(0);
1798 1799 1800 1801 1802
	struct coredump_params cprm = {
		.signr = signr,
		.regs = regs,
		.limit = current->signal->rlim[RLIMIT_CORE].rlim_cur,
	};
L
Linus Torvalds 已提交
1803

S
Steve Grubb 已提交
1804 1805
	audit_core_dumps(signr);

1806
	binfmt = mm->binfmt;
L
Linus Torvalds 已提交
1807 1808
	if (!binfmt || !binfmt->core_dump)
		goto fail;
D
David Howells 已提交
1809 1810 1811 1812 1813 1814 1815

	cred = prepare_creds();
	if (!cred) {
		retval = -ENOMEM;
		goto fail;
	}

L
Linus Torvalds 已提交
1816
	down_write(&mm->mmap_sem);
R
Roland McGrath 已提交
1817 1818 1819
	/*
	 * If another thread got here first, or we are not dumpable, bail out.
	 */
1820
	if (mm->core_state || !get_dumpable(mm)) {
L
Linus Torvalds 已提交
1821
		up_write(&mm->mmap_sem);
D
David Howells 已提交
1822
		put_cred(cred);
L
Linus Torvalds 已提交
1823 1824
		goto fail;
	}
A
Alan Cox 已提交
1825 1826 1827 1828 1829 1830

	/*
	 *	We cannot trust fsuid as being the "true" uid of the
	 *	process nor do we know its entire history. We only know it
	 *	was tainted so we dump it as root in mode 2.
	 */
1831
	if (get_dumpable(mm) == 2) {	/* Setuid core dump mode */
A
Alan Cox 已提交
1832
		flag = O_EXCL;		/* Stop rewrite attacks */
D
David Howells 已提交
1833
		cred->fsuid = 0;	/* Dump root private */
A
Alan Cox 已提交
1834
	}
1835

1836
	retval = coredump_wait(exit_code, &core_state);
D
David Howells 已提交
1837 1838
	if (retval < 0) {
		put_cred(cred);
1839
		goto fail;
D
David Howells 已提交
1840 1841 1842
	}

	old_cred = override_creds(cred);
L
Linus Torvalds 已提交
1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854

	/*
	 * Clear any false indication of pending signals that might
	 * be seen by the filesystem code called to write the core file.
	 */
	clear_thread_flag(TIF_SIGPENDING);

	/*
	 * lock_kernel() because format_corename() is controlled by sysctl, which
	 * uses lock_kernel()
	 */
 	lock_kernel();
1855
	ispipe = format_corename(corename, signr);
L
Linus Torvalds 已提交
1856
	unlock_kernel();
1857

1858
	if ((!ispipe) && (cprm.limit < binfmt->min_coredump))
1859 1860
		goto fail_unlock;

1861
 	if (ispipe) {
1862
		if (cprm.limit == 0) {
1863 1864 1865
			/*
			 * Normally core limits are irrelevant to pipes, since
			 * we're not writing to the file system, but we use
1866
			 * cprm.limit of 0 here as a speacial value. Any
1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883
			 * non-zero limit gets set to RLIM_INFINITY below, but
			 * a limit of 0 skips the dump.  This is a consistent
			 * way to catch recursive crashes.  We can still crash
			 * if the core_pattern binary sets RLIM_CORE =  !0
			 * but it runs as root, and can do lots of stupid things
			 * Note that we use task_tgid_vnr here to grab the pid
			 * of the process group leader.  That way we get the
			 * right pid if a thread in a multi-threaded
			 * core_pattern process dies.
			 */
			printk(KERN_WARNING
				"Process %d(%s) has RLIMIT_CORE set to 0\n",
				task_tgid_vnr(current), current->comm);
			printk(KERN_WARNING "Aborting core\n");
			goto fail_unlock;
		}

1884 1885 1886 1887 1888 1889 1890 1891
		dump_count = atomic_inc_return(&core_dump_count);
		if (core_pipe_limit && (core_pipe_limit < dump_count)) {
			printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
			       task_tgid_vnr(current), current->comm);
			printk(KERN_WARNING "Skipping core dump\n");
			goto fail_dropcount;
		}

1892
		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1893 1894 1895
		if (!helper_argv) {
			printk(KERN_WARNING "%s failed to allocate memory\n",
			       __func__);
1896
			goto fail_dropcount;
1897
		}
1898

1899
		cprm.limit = RLIM_INFINITY;
1900

1901
		/* SIGPIPE can happen, but it's just never processed */
1902
		if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
1903
				&cprm.file)) {
1904 1905
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
1906
			goto fail_dropcount;
1907 1908
 		}
 	} else
1909
		cprm.file = filp_open(corename,
1910 1911
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
1912
	if (IS_ERR(cprm.file))
1913
		goto fail_dropcount;
1914
	inode = cprm.file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1915 1916
	if (inode->i_nlink > 1)
		goto close_fail;	/* multiple links - don't dump */
1917
	if (!ispipe && d_unhashed(cprm.file->f_path.dentry))
L
Linus Torvalds 已提交
1918 1919
		goto close_fail;

1920 1921 1922
	/* AK: actually i see no reason to not allow this for named pipes etc.,
	   but keep the previous behaviour for now. */
	if (!ispipe && !S_ISREG(inode->i_mode))
L
Linus Torvalds 已提交
1923
		goto close_fail;
I
Ingo Molnar 已提交
1924 1925 1926 1927
	/*
	 * Dont allow local users get cute and trick others to coredump
	 * into their pre-created files:
	 */
1928
	if (inode->i_uid != current_fsuid())
I
Ingo Molnar 已提交
1929
		goto close_fail;
1930
	if (!cprm.file->f_op)
L
Linus Torvalds 已提交
1931
		goto close_fail;
1932
	if (!cprm.file->f_op->write)
L
Linus Torvalds 已提交
1933
		goto close_fail;
1934 1935
	if (!ispipe &&
	    do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file) != 0)
L
Linus Torvalds 已提交
1936 1937
		goto close_fail;

1938
	retval = binfmt->core_dump(&cprm);
L
Linus Torvalds 已提交
1939 1940 1941 1942

	if (retval)
		current->signal->group_exit_code |= 0x80;
close_fail:
1943
	if (ispipe && core_pipe_limit)
1944 1945
		wait_for_dump_helpers(cprm.file);
	filp_close(cprm.file, NULL);
1946 1947 1948
fail_dropcount:
	if (dump_count)
		atomic_dec(&core_dump_count);
L
Linus Torvalds 已提交
1949
fail_unlock:
1950 1951 1952
	if (helper_argv)
		argv_free(helper_argv);

D
David Howells 已提交
1953 1954
	revert_creds(old_cred);
	put_cred(cred);
O
Oleg Nesterov 已提交
1955
	coredump_finish(mm);
L
Linus Torvalds 已提交
1956
fail:
W
WANG Cong 已提交
1957
	return;
L
Linus Torvalds 已提交
1958
}