exec.c 43.2 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>
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#include <linux/ima.h>
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#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 <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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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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#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);
		if (ret) {
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			up_write(&mm->mmap_sem);
			return ret;
		}
	}

631 632 633 634 635 636 637 638 639 640
#ifdef CONFIG_STACK_GROWSUP
	stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#else
	stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#endif
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
L
Linus Torvalds 已提交
641 642 643 644 645 646 647 648 649 650
	up_write(&mm->mmap_sem);
	return 0;
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct file *file;
651
	int err;
L
Linus Torvalds 已提交
652

653 654 655 656
	file = do_filp_open(AT_FDCWD, name,
				O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
				MAY_EXEC | MAY_OPEN);
	if (IS_ERR(file))
657 658 659
		goto out;

	err = -EACCES;
660 661
	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
		goto exit;
662

663 664
	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
		goto exit;
665

666 667
	fsnotify_open(file->f_path.dentry);

668
	err = deny_write_access(file);
669 670
	if (err)
		goto exit;
L
Linus Torvalds 已提交
671

672
out:
673 674
	return file;

675 676
exit:
	fput(file);
677 678
	return ERR_PTR(err);
}
L
Linus Torvalds 已提交
679 680
EXPORT_SYMBOL(open_exec);

M
Mimi Zohar 已提交
681 682
int kernel_read(struct file *file, loff_t offset,
		char *addr, unsigned long count)
L
Linus Torvalds 已提交
683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
{
	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;
	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
713
		 * checking core_state and changing tsk->mm.
L
Linus Torvalds 已提交
714 715
		 */
		down_read(&old_mm->mmap_sem);
716
		if (unlikely(old_mm->core_state)) {
L
Linus Torvalds 已提交
717 718 719 720 721 722 723 724 725 726 727 728 729
			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);
730
		BUG_ON(active_mm != old_mm);
731
		mm_update_next_owner(old_mm);
L
Linus Torvalds 已提交
732 733 734 735 736 737 738 739 740 741 742 743 744
		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().)
 */
745
static int de_thread(struct task_struct *tsk)
L
Linus Torvalds 已提交
746 747
{
	struct signal_struct *sig = tsk->signal;
748
	struct sighand_struct *oldsighand = tsk->sighand;
L
Linus Torvalds 已提交
749 750 751
	spinlock_t *lock = &oldsighand->siglock;
	int count;

752
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
753 754 755 756 757 758
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
759
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
760 761 762 763 764 765 766
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
767
	sig->group_exit_task = tsk;
768
	zap_other_threads(tsk);
L
Linus Torvalds 已提交
769

770 771
	/* Account for the thread group leader hanging around: */
	count = thread_group_leader(tsk) ? 1 : 2;
772
	sig->notify_count = count;
L
Linus Torvalds 已提交
773 774 775 776 777 778 779 780 781 782 783 784 785
	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:
	 */
786
	if (!thread_group_leader(tsk)) {
787
		struct task_struct *leader = tsk->group_leader;
788

789
		sig->notify_count = -1;	/* for exit_notify() */
790 791 792 793 794 795 796 797
		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
798

799 800 801 802 803 804 805 806 807 808
		/*
		 * 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).
		 */
809
		tsk->start_time = leader->start_time;
810

811 812
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
813 814 815 816 817 818
		/*
		 * 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:
		 */
819 820

		/* Become a process group leader with the old leader's pid.
821 822
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
823 824
		 *       is called.  Odd but simple and correct.
		 */
825 826
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
827
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
828 829 830
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
		list_replace_rcu(&leader->tasks, &tsk->tasks);
L
Linus Torvalds 已提交
831

832 833
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
834

835
		tsk->exit_signal = SIGCHLD;
836 837 838

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
839
		write_unlock_irq(&tasklist_lock);
840 841

		release_task(leader);
842
	}
L
Linus Torvalds 已提交
843

844 845
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
846 847

no_thread_group:
J
Jiri Pirko 已提交
848 849 850
	if (current->mm)
		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);

L
Linus Torvalds 已提交
851
	exit_itimers(sig);
852
	flush_itimer_signals();
853

854 855
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
856
		/*
857 858
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
859
		 */
860 861 862 863
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
864 865 866 867 868 869
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
870
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
871 872 873
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

874
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
875 876
	}

877
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
878 879
	return 0;
}
O
Oleg Nesterov 已提交
880

L
Linus Torvalds 已提交
881 882 883 884
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
885
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
886 887
{
	long j = -1;
888
	struct fdtable *fdt;
L
Linus Torvalds 已提交
889 890 891 892 893 894 895

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

		j++;
		i = j * __NFDBITS;
896
		fdt = files_fdtable(files);
897
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
898
			break;
899
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
900 901
		if (!set)
			continue;
902
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
903 904 905 906 907 908 909 910 911 912 913 914
		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);
}

915
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
916 917 918 919 920
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
921
	return buf;
L
Linus Torvalds 已提交
922 923 924 925 926 927 928
}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
929
	perf_event_comm(tsk);
L
Linus Torvalds 已提交
930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945
}

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

	/*
	 * 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
946 947
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
948 949 950 951 952
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
953
		goto out;
L
Linus Torvalds 已提交
954 955 956 957 958 959

	bprm->mm = NULL;		/* We're using it now */

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

960
	if (current_euid() == current_uid() && current_egid() == current_gid())
961
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
962
	else
963
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
964

L
Linus Torvalds 已提交
965
	name = bprm->filename;
966 967

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
968 969
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
970
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
971 972 973 974 975 976 977 978 979 980
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

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

981 982 983 984 985 986
	/* 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;

987 988 989
	/* install the new credentials */
	if (bprm->cred->uid != current_euid() ||
	    bprm->cred->gid != current_egid()) {
990 991
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
992
		   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
993
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
994 995
	}

996 997
	current->personality &= ~bprm->per_clear;

I
Ingo Molnar 已提交
998 999 1000 1001 1002
	/*
	 * Flush performance counters when crossing a
	 * security domain:
	 */
	if (!get_dumpable(current->mm))
1003
		perf_event_exit_task(current);
I
Ingo Molnar 已提交
1004

L
Linus Torvalds 已提交
1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
	/* 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);

	return 0;

out:
	return retval;
}

EXPORT_SYMBOL(flush_old_exec);

1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049
/*
 * 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);
}

1050 1051 1052 1053 1054 1055 1056 1057 1058
/*
 * 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;
1059 1060
	/*
	 * cred_guard_mutex must be held at least to this point to prevent
1061
	 * ptrace_attach() from altering our determination of the task's
1062 1063
	 * credentials; any time after this it may be unlocked.
	 */
1064
	security_bprm_committed_creds(bprm);
1065
	mutex_unlock(&current->cred_guard_mutex);
1066 1067 1068 1069 1070
}
EXPORT_SYMBOL(install_exec_creds);

/*
 * determine how safe it is to execute the proposed program
1071
 * - the caller must hold current->cred_guard_mutex to protect against
1072 1073
 *   PTRACE_ATTACH
 */
A
Al Viro 已提交
1074
int check_unsafe_exec(struct linux_binprm *bprm)
1075
{
D
David Howells 已提交
1076
	struct task_struct *p = current, *t;
1077
	unsigned n_fs;
A
Al Viro 已提交
1078
	int res = 0;
1079 1080 1081

	bprm->unsafe = tracehook_unsafe_exec(p);

D
David Howells 已提交
1082
	n_fs = 1;
A
Al Viro 已提交
1083
	write_lock(&p->fs->lock);
1084
	rcu_read_lock();
D
David Howells 已提交
1085 1086 1087 1088
	for (t = next_thread(p); t != p; t = next_thread(t)) {
		if (t->fs == p->fs)
			n_fs++;
	}
1089
	rcu_read_unlock();
D
David Howells 已提交
1090

1091
	if (p->fs->users > n_fs) {
1092
		bprm->unsafe |= LSM_UNSAFE_SHARE;
A
Al Viro 已提交
1093
	} else {
1094 1095 1096 1097 1098
		res = -EAGAIN;
		if (!p->fs->in_exec) {
			p->fs->in_exec = 1;
			res = 1;
		}
A
Al Viro 已提交
1099 1100 1101 1102
	}
	write_unlock(&p->fs->lock);

	return res;
1103 1104
}

L
Linus Torvalds 已提交
1105 1106 1107
/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1108 1109
 *
 * This may be called multiple times for binary chains (scripts for example).
L
Linus Torvalds 已提交
1110 1111 1112
 */
int prepare_binprm(struct linux_binprm *bprm)
{
1113
	umode_t mode;
1114
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1115 1116 1117 1118 1119 1120
	int retval;

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

1121 1122 1123
	/* 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
1124

1125
	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1126 1127
		/* Set-uid? */
		if (mode & S_ISUID) {
1128 1129
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->euid = inode->i_uid;
L
Linus Torvalds 已提交
1130 1131 1132 1133 1134 1135 1136 1137 1138
		}

		/* 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)) {
1139 1140
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->egid = inode->i_gid;
L
Linus Torvalds 已提交
1141 1142 1143 1144
		}
	}

	/* fill in binprm security blob */
1145
	retval = security_bprm_set_creds(bprm);
L
Linus Torvalds 已提交
1146 1147
	if (retval)
		return retval;
1148
	bprm->cred_prepared = 1;
L
Linus Torvalds 已提交
1149

1150 1151
	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
L
Linus Torvalds 已提交
1152 1153 1154 1155
}

EXPORT_SYMBOL(prepare_binprm);

N
Nick Piggin 已提交
1156 1157 1158 1159 1160
/*
 * 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.
 */
1161
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1162
{
1163 1164 1165 1166
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1167

1168 1169
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1170

1171 1172 1173 1174 1175 1176 1177 1178
	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
1179

1180 1181 1182
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1183

1184 1185
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1186

1187 1188 1189
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1190

1191 1192 1193
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1194

1195 1196
out:
	return ret;
L
Linus Torvalds 已提交
1197 1198 1199 1200 1201 1202 1203 1204
}
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)
{
1205
	unsigned int depth = bprm->recursion_depth;
L
Linus Torvalds 已提交
1206 1207 1208 1209
	int try,retval;
	struct linux_binfmt *fmt;

	retval = security_bprm_check(bprm);
M
Mimi Zohar 已提交
1210 1211 1212
	if (retval)
		return retval;
	retval = ima_bprm_check(bprm);
L
Linus Torvalds 已提交
1213 1214 1215 1216 1217 1218
	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
1219 1220 1221 1222 1223

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

L
Linus Torvalds 已提交
1224 1225 1226
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1227
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1228 1229 1230 1231 1232 1233 1234
			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);
1235 1236 1237 1238 1239 1240
			/*
			 * 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
1241
			if (retval >= 0) {
1242 1243
				if (depth == 0)
					tracehook_report_exec(fmt, bprm, regs);
L
Linus Torvalds 已提交
1244 1245 1246 1247 1248 1249
				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
1250
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
				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
1265 1266
#ifdef CONFIG_MODULES
		} else {
L
Linus Torvalds 已提交
1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
#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;
1292
	struct files_struct *displaced;
1293
	bool clear_in_exec;
L
Linus Torvalds 已提交
1294 1295
	int retval;

1296
	retval = unshare_files(&displaced);
1297 1298 1299
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1300
	retval = -ENOMEM;
1301
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1302
	if (!bprm)
1303
		goto out_files;
L
Linus Torvalds 已提交
1304

1305 1306
	retval = prepare_bprm_creds(bprm);
	if (retval)
1307
		goto out_free;
A
Al Viro 已提交
1308 1309

	retval = check_unsafe_exec(bprm);
1310
	if (retval < 0)
1311
		goto out_free;
1312
	clear_in_exec = retval;
1313
	current->in_execve = 1;
1314

L
Linus Torvalds 已提交
1315 1316 1317
	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
A
Al Viro 已提交
1318
		goto out_unmark;
L
Linus Torvalds 已提交
1319 1320 1321 1322 1323 1324 1325

	sched_exec();

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

1326 1327 1328
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1329

1330
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1331
	if ((retval = bprm->argc) < 0)
1332
		goto out;
L
Linus Torvalds 已提交
1333

1334
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354
	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
1355
	current->flags &= ~PF_KTHREAD;
L
Linus Torvalds 已提交
1356
	retval = search_binary_handler(bprm,regs);
1357 1358
	if (retval < 0)
		goto out;
L
Linus Torvalds 已提交
1359

1360
	/* execve succeeded */
A
Al Viro 已提交
1361
	current->fs->in_exec = 0;
1362
	current->in_execve = 0;
1363 1364 1365 1366 1367
	acct_update_integrals(current);
	free_bprm(bprm);
	if (displaced)
		put_files_struct(displaced);
	return retval;
L
Linus Torvalds 已提交
1368

1369
out:
L
Linus Torvalds 已提交
1370
	if (bprm->mm)
1371
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1372 1373 1374 1375 1376 1377

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
1378

A
Al Viro 已提交
1379
out_unmark:
1380 1381
	if (clear_in_exec)
		current->fs->in_exec = 0;
1382
	current->in_execve = 0;
1383 1384

out_free:
1385
	free_bprm(bprm);
L
Linus Torvalds 已提交
1386

1387
out_files:
1388 1389
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413
out_ret:
	return retval;
}

int set_binfmt(struct linux_binfmt *new)
{
	struct linux_binfmt *old = current->binfmt;

	if (new) {
		if (!try_module_get(new->module))
			return -1;
	}
	current->binfmt = new;
	if (old)
		module_put(old->module);
	return 0;
}

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.
 */
1414
static int format_corename(char *corename, long signr)
L
Linus Torvalds 已提交
1415
{
1416
	const struct cred *cred = current_cred();
1417 1418
	const char *pat_ptr = core_pattern;
	int ispipe = (*pat_ptr == '|');
L
Linus Torvalds 已提交
1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444
	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,
1445
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1446 1447 1448 1449 1450 1451 1452
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
1453
					      "%d", cred->uid);
L
Linus Torvalds 已提交
1454 1455 1456 1457 1458 1459 1460
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
1461
					      "%d", cred->gid);
L
Linus Torvalds 已提交
1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488
				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,
1489
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502
				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;
1503 1504 1505 1506 1507 1508 1509 1510
			/* 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
1511 1512 1513 1514 1515 1516 1517 1518 1519 1520
			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
1521
	 * the filename. Do not do this for piped commands. */
1522
	if (!ispipe && !pid_in_pattern && core_uses_pid) {
L
Linus Torvalds 已提交
1523
		rc = snprintf(out_ptr, out_end - out_ptr,
1524
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1525 1526 1527 1528
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1529
out:
L
Linus Torvalds 已提交
1530
	*out_ptr = 0;
1531
	return ispipe;
L
Linus Torvalds 已提交
1532 1533
}

1534
static int zap_process(struct task_struct *start)
1535 1536
{
	struct task_struct *t;
1537
	int nr = 0;
1538

1539 1540
	start->signal->flags = SIGNAL_GROUP_EXIT;
	start->signal->group_stop_count = 0;
1541 1542 1543 1544

	t = start;
	do {
		if (t != current && t->mm) {
1545 1546
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1547
			nr++;
1548
		}
1549
	} while_each_thread(start, t);
1550 1551

	return nr;
1552 1553
}

1554
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1555
				struct core_state *core_state, int exit_code)
L
Linus Torvalds 已提交
1556 1557
{
	struct task_struct *g, *p;
1558
	unsigned long flags;
1559
	int nr = -EAGAIN;
1560 1561

	spin_lock_irq(&tsk->sighand->siglock);
1562
	if (!signal_group_exit(tsk->signal)) {
1563
		mm->core_state = core_state;
1564
		tsk->signal->group_exit_code = exit_code;
1565
		nr = zap_process(tsk);
L
Linus Torvalds 已提交
1566
	}
1567
	spin_unlock_irq(&tsk->sighand->siglock);
1568 1569
	if (unlikely(nr < 0))
		return nr;
L
Linus Torvalds 已提交
1570

1571
	if (atomic_read(&mm->mm_users) == nr + 1)
1572
		goto done;
1573 1574
	/*
	 * We should find and kill all tasks which use this mm, and we should
1575
	 * count them correctly into ->nr_threads. We don't take tasklist
1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602
	 * 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().
	 */
1603
	rcu_read_lock();
1604
	for_each_process(g) {
1605 1606
		if (g == tsk->group_leader)
			continue;
1607 1608
		if (g->flags & PF_KTHREAD)
			continue;
1609 1610 1611
		p = g;
		do {
			if (p->mm) {
1612
				if (unlikely(p->mm == mm)) {
1613
					lock_task_sighand(p, &flags);
1614
					nr += zap_process(p);
1615 1616
					unlock_task_sighand(p, &flags);
				}
1617 1618
				break;
			}
1619
		} while_each_thread(g, p);
1620
	}
1621
	rcu_read_unlock();
1622
done:
1623
	atomic_set(&core_state->nr_threads, nr);
1624
	return nr;
L
Linus Torvalds 已提交
1625 1626
}

1627
static int coredump_wait(int exit_code, struct core_state *core_state)
L
Linus Torvalds 已提交
1628
{
1629 1630 1631
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion *vfork_done;
O
Oleg Nesterov 已提交
1632
	int core_waiters;
L
Linus Torvalds 已提交
1633

1634
	init_completion(&core_state->startup);
1635 1636
	core_state->dumper.task = tsk;
	core_state->dumper.next = NULL;
1637
	core_waiters = zap_threads(tsk, mm, core_state, exit_code);
O
Oleg Nesterov 已提交
1638 1639
	up_write(&mm->mmap_sem);

1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652
	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
1653
	if (core_waiters)
1654
		wait_for_completion(&core_state->startup);
1655 1656
fail:
	return core_waiters;
L
Linus Torvalds 已提交
1657 1658
}

O
Oleg Nesterov 已提交
1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679
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;
}

1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728
/*
 * 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;
}

W
WANG Cong 已提交
1729
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
L
Linus Torvalds 已提交
1730
{
1731
	struct core_state core_state;
L
Linus Torvalds 已提交
1732 1733 1734 1735 1736
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
	struct inode * inode;
	struct file * file;
D
David Howells 已提交
1737 1738
	const struct cred *old_cred;
	struct cred *cred;
L
Linus Torvalds 已提交
1739
	int retval = 0;
A
Alan Cox 已提交
1740
	int flag = 0;
1741
	int ispipe = 0;
1742
	unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1743 1744 1745
	char **helper_argv = NULL;
	int helper_argc = 0;
	char *delimit;
L
Linus Torvalds 已提交
1746

S
Steve Grubb 已提交
1747 1748
	audit_core_dumps(signr);

L
Linus Torvalds 已提交
1749 1750 1751
	binfmt = current->binfmt;
	if (!binfmt || !binfmt->core_dump)
		goto fail;
D
David Howells 已提交
1752 1753 1754 1755 1756 1757 1758

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

L
Linus Torvalds 已提交
1759
	down_write(&mm->mmap_sem);
R
Roland McGrath 已提交
1760 1761 1762
	/*
	 * If another thread got here first, or we are not dumpable, bail out.
	 */
1763
	if (mm->core_state || !get_dumpable(mm)) {
L
Linus Torvalds 已提交
1764
		up_write(&mm->mmap_sem);
D
David Howells 已提交
1765
		put_cred(cred);
L
Linus Torvalds 已提交
1766 1767
		goto fail;
	}
A
Alan Cox 已提交
1768 1769 1770 1771 1772 1773

	/*
	 *	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.
	 */
1774
	if (get_dumpable(mm) == 2) {	/* Setuid core dump mode */
A
Alan Cox 已提交
1775
		flag = O_EXCL;		/* Stop rewrite attacks */
D
David Howells 已提交
1776
		cred->fsuid = 0;	/* Dump root private */
A
Alan Cox 已提交
1777
	}
1778

1779
	retval = coredump_wait(exit_code, &core_state);
D
David Howells 已提交
1780 1781
	if (retval < 0) {
		put_cred(cred);
1782
		goto fail;
D
David Howells 已提交
1783 1784 1785
	}

	old_cred = override_creds(cred);
L
Linus Torvalds 已提交
1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797

	/*
	 * 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();
1798
	ispipe = format_corename(corename, signr);
L
Linus Torvalds 已提交
1799
	unlock_kernel();
1800 1801 1802 1803 1804 1805 1806 1807
	/*
	 * Don't bother to check the RLIMIT_CORE value if core_pattern points
	 * to a pipe.  Since we're not writing directly to the filesystem
	 * RLIMIT_CORE doesn't really apply, as no actual core file will be
	 * created unless the pipe reader choses to write out the core file
	 * at which point file size limits and permissions will be imposed
	 * as it does with any other process
	 */
1808
	if ((!ispipe) && (core_limit < binfmt->min_coredump))
1809 1810
		goto fail_unlock;

1811
 	if (ispipe) {
1812
		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1813 1814 1815 1816 1817
		if (!helper_argv) {
			printk(KERN_WARNING "%s failed to allocate memory\n",
			       __func__);
			goto fail_unlock;
		}
1818 1819 1820 1821
		/* Terminate the string before the first option */
		delimit = strchr(corename, ' ');
		if (delimit)
			*delimit = '\0';
1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834
		delimit = strrchr(helper_argv[0], '/');
		if (delimit)
			delimit++;
		else
			delimit = helper_argv[0];
		if (!strcmp(delimit, current->comm)) {
			printk(KERN_NOTICE "Recursive core dump detected, "
					"aborting\n");
			goto fail_unlock;
		}

		core_limit = RLIM_INFINITY;

1835
		/* SIGPIPE can happen, but it's just never processed */
1836 1837
 		if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
				&file)) {
1838 1839 1840 1841 1842 1843
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
 			goto fail_unlock;
 		}
 	} else
 		file = filp_open(corename,
1844 1845
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
L
Linus Torvalds 已提交
1846 1847
	if (IS_ERR(file))
		goto fail_unlock;
1848
	inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1849 1850
	if (inode->i_nlink > 1)
		goto close_fail;	/* multiple links - don't dump */
1851
	if (!ispipe && d_unhashed(file->f_path.dentry))
L
Linus Torvalds 已提交
1852 1853
		goto close_fail;

1854 1855 1856
	/* 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
1857
		goto close_fail;
I
Ingo Molnar 已提交
1858 1859 1860 1861
	/*
	 * Dont allow local users get cute and trick others to coredump
	 * into their pre-created files:
	 */
1862
	if (inode->i_uid != current_fsuid())
I
Ingo Molnar 已提交
1863
		goto close_fail;
L
Linus Torvalds 已提交
1864 1865 1866 1867
	if (!file->f_op)
		goto close_fail;
	if (!file->f_op->write)
		goto close_fail;
1868
	if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
L
Linus Torvalds 已提交
1869 1870
		goto close_fail;

1871
	retval = binfmt->core_dump(signr, regs, file, core_limit);
L
Linus Torvalds 已提交
1872 1873 1874 1875 1876 1877

	if (retval)
		current->signal->group_exit_code |= 0x80;
close_fail:
	filp_close(file, NULL);
fail_unlock:
1878 1879 1880
	if (helper_argv)
		argv_free(helper_argv);

D
David Howells 已提交
1881 1882
	revert_creds(old_cred);
	put_cred(cred);
O
Oleg Nesterov 已提交
1883
	coredump_finish(mm);
L
Linus Torvalds 已提交
1884
fail:
W
WANG Cong 已提交
1885
	return;
L
Linus Torvalds 已提交
1886
}