exec.c 51.2 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>
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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/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 <linux/oom.h>
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#include <linux/compat.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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struct core_name {
	char *corename;
	int used, size;
};
static atomic_t call_count = ATOMIC_INIT(1);

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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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	static const struct open_flags uselib_flags = {
		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
		.acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
		.intent = LOOKUP_OPEN
	};
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	if (IS_ERR(tmp))
		goto out;

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	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
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	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);
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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
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/*
 * The nascent bprm->mm is not visible until exec_mmap() but it can
 * use a lot of memory, account these pages in current->mm temporary
 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
 * change the counter back via acct_arg_size(0).
 */
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static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
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{
	struct mm_struct *mm = current->mm;
	long diff = (long)(pages - bprm->vma_pages);

	if (!mm || !diff)
		return;

	bprm->vma_pages = pages;

#ifdef SPLIT_RSS_COUNTING
	add_mm_counter(mm, MM_ANONPAGES, diff);
#else
	spin_lock(&mm->page_table_lock);
	add_mm_counter(mm, MM_ANONPAGES, diff);
	spin_unlock(&mm->page_table_lock);
#endif
}

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

#ifdef CONFIG_STACK_GROWSUP
	if (write) {
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		ret = expand_downwards(bprm->vma, pos);
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		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;

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		acct_arg_size(bprm, size / PAGE_SIZE);

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		/*
		 * 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 > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
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			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.
	 */
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	BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
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	vma->vm_end = STACK_TOP_MAX;
	vma->vm_start = vma->vm_end - PAGE_SIZE;
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	vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
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	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
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	INIT_LIST_HEAD(&vma->anon_vma_chain);
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	err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
	if (err)
		goto err;

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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

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static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
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{
}

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static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
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		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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struct user_arg_ptr {
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#ifdef CONFIG_COMPAT
	bool is_compat;
#endif
	union {
		const char __user *const __user *native;
#ifdef CONFIG_COMPAT
		compat_uptr_t __user *compat;
#endif
	} ptr;
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};

static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
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{
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	const char __user *native;

#ifdef CONFIG_COMPAT
	if (unlikely(argv.is_compat)) {
		compat_uptr_t compat;

		if (get_user(compat, argv.ptr.compat + nr))
			return ERR_PTR(-EFAULT);
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		return compat_ptr(compat);
	}
#endif

	if (get_user(native, argv.ptr.native + nr))
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		return ERR_PTR(-EFAULT);

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	return native;
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}

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

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	if (argv.ptr.native != NULL) {
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		for (;;) {
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			const char __user *p = get_user_arg_ptr(argv, i);
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			if (!p)
				break;
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			if (IS_ERR(p))
				return -EFAULT;

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			if (i++ >= max)
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				return -E2BIG;
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			if (fatal_signal_pending(current))
				return -ERESTARTNOHAND;
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			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, struct user_arg_ptr argv,
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			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) {
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		const char __user *str;
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		int len;
		unsigned long pos;

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		ret = -EFAULT;
		str = get_user_arg_ptr(argv, argc);
		if (IS_ERR(str))
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			goto out;

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		len = strnlen_user(str, MAX_ARG_STRLEN);
		if (!len)
			goto out;

		ret = -E2BIG;
		if (!valid_arg_len(bprm, len))
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			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;

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			if (fatal_signal_pending(current)) {
				ret = -ERESTARTNOHAND;
				goto out;
			}
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			cond_resched();

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			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.
 */
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int copy_strings_kernel(int argc, const char *const *__argv,
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			struct linux_binprm *bprm)
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{
	int r;
	mm_segment_t oldfs = get_fs();
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	struct user_arg_ptr argv = {
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		.ptr.native = (const char __user *const  __user *)__argv,
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	};

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	set_fs(KERNEL_DS);
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	r = copy_strings(argc, argv, bprm);
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	set_fs(oldfs);
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	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;
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	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)
	 */
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	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
		return -ENOMEM;
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	/*
	 * 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();
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	tlb_gather_mmu(&tlb, mm, 0);
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	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,
634 635 636 637 638 639 640 641
			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.
		 */
P
Peter Zijlstra 已提交
642
		free_pgd_range(&tlb, old_start, old_end, new_end,
643
			vma->vm_next ? vma->vm_next->vm_start : 0);
L
Linus Torvalds 已提交
644
	}
P
Peter Zijlstra 已提交
645
	tlb_finish_mmu(&tlb, new_end, old_end);
646 647

	/*
648
	 * Shrink the vma to just the new range.  Always succeeds.
649 650 651 652
	 */
	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);

	return 0;
L
Linus Torvalds 已提交
653 654
}

655 656 657 658
/*
 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 * the stack is optionally relocated, and some extra space is added.
 */
L
Linus Torvalds 已提交
659 660 661 662
int setup_arg_pages(struct linux_binprm *bprm,
		    unsigned long stack_top,
		    int executable_stack)
{
663 664
	unsigned long ret;
	unsigned long stack_shift;
L
Linus Torvalds 已提交
665
	struct mm_struct *mm = current->mm;
666 667 668 669
	struct vm_area_struct *vma = bprm->vma;
	struct vm_area_struct *prev = NULL;
	unsigned long vm_flags;
	unsigned long stack_base;
670 671 672
	unsigned long stack_size;
	unsigned long stack_expand;
	unsigned long rlim_stack;
L
Linus Torvalds 已提交
673 674 675

#ifdef CONFIG_STACK_GROWSUP
	/* Limit stack size to 1GB */
J
Jiri Slaby 已提交
676
	stack_base = rlimit_max(RLIMIT_STACK);
L
Linus Torvalds 已提交
677 678 679
	if (stack_base > (1 << 30))
		stack_base = 1 << 30;

680 681 682
	/* Make sure we didn't let the argument array grow too large. */
	if (vma->vm_end - vma->vm_start > stack_base)
		return -ENOMEM;
L
Linus Torvalds 已提交
683

684
	stack_base = PAGE_ALIGN(stack_top - stack_base);
L
Linus Torvalds 已提交
685

686 687 688
	stack_shift = vma->vm_start - stack_base;
	mm->arg_start = bprm->p - stack_shift;
	bprm->p = vma->vm_end - stack_shift;
L
Linus Torvalds 已提交
689
#else
690 691
	stack_top = arch_align_stack(stack_top);
	stack_top = PAGE_ALIGN(stack_top);
692 693 694 695 696

	if (unlikely(stack_top < mmap_min_addr) ||
	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
		return -ENOMEM;

697 698 699
	stack_shift = vma->vm_end - stack_top;

	bprm->p -= stack_shift;
L
Linus Torvalds 已提交
700 701 702 703
	mm->arg_start = bprm->p;
#endif

	if (bprm->loader)
704 705
		bprm->loader -= stack_shift;
	bprm->exec -= stack_shift;
L
Linus Torvalds 已提交
706 707

	down_write(&mm->mmap_sem);
708
	vm_flags = VM_STACK_FLAGS;
709 710 711 712 713 714 715 716 717 718 719

	/*
	 * 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;
720
	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
721 722 723 724 725 726 727 728 729 730

	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);
731 732
		if (ret)
			goto out_unlock;
L
Linus Torvalds 已提交
733 734
	}

735 736 737
	/* mprotect_fixup is overkill to remove the temporary stack flags */
	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;

738
	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
739 740 741 742 743 744
	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;
745
#ifdef CONFIG_STACK_GROWSUP
746 747 748 749
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_start + rlim_stack;
	else
		stack_base = vma->vm_end + stack_expand;
750
#else
751 752 753 754
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_end - rlim_stack;
	else
		stack_base = vma->vm_start - stack_expand;
755
#endif
756
	current->mm->start_stack = bprm->p;
757 758 759 760 761
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
L
Linus Torvalds 已提交
762
	up_write(&mm->mmap_sem);
763
	return ret;
L
Linus Torvalds 已提交
764 765 766 767 768 769 770 771
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct file *file;
772
	int err;
773 774 775 776 777
	static const struct open_flags open_exec_flags = {
		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
		.acc_mode = MAY_EXEC | MAY_OPEN,
		.intent = LOOKUP_OPEN
	};
L
Linus Torvalds 已提交
778

779
	file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
780
	if (IS_ERR(file))
781 782 783
		goto out;

	err = -EACCES;
784 785
	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
		goto exit;
786

787 788
	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
		goto exit;
789

790
	fsnotify_open(file);
791

792
	err = deny_write_access(file);
793 794
	if (err)
		goto exit;
L
Linus Torvalds 已提交
795

796
out:
797 798
	return file;

799 800
exit:
	fput(file);
801 802
	return ERR_PTR(err);
}
L
Linus Torvalds 已提交
803 804
EXPORT_SYMBOL(open_exec);

M
Mimi Zohar 已提交
805 806
int kernel_read(struct file *file, loff_t offset,
		char *addr, unsigned long count)
L
Linus Torvalds 已提交
807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829
{
	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;
830
	sync_mm_rss(tsk, old_mm);
L
Linus Torvalds 已提交
831 832 833 834 835 836 837
	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
838
		 * checking core_state and changing tsk->mm.
L
Linus Torvalds 已提交
839 840
		 */
		down_read(&old_mm->mmap_sem);
841
		if (unlikely(old_mm->core_state)) {
L
Linus Torvalds 已提交
842 843 844 845 846 847 848 849 850
			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);
Y
Ying Han 已提交
851 852 853 854
	if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
		atomic_dec(&old_mm->oom_disable_count);
		atomic_inc(&tsk->mm->oom_disable_count);
	}
L
Linus Torvalds 已提交
855 856 857 858
	task_unlock(tsk);
	arch_pick_mmap_layout(mm);
	if (old_mm) {
		up_read(&old_mm->mmap_sem);
859
		BUG_ON(active_mm != old_mm);
860
		mm_update_next_owner(old_mm);
L
Linus Torvalds 已提交
861 862 863 864 865 866 867 868 869 870 871 872 873
		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().)
 */
874
static int de_thread(struct task_struct *tsk)
L
Linus Torvalds 已提交
875 876
{
	struct signal_struct *sig = tsk->signal;
877
	struct sighand_struct *oldsighand = tsk->sighand;
L
Linus Torvalds 已提交
878 879
	spinlock_t *lock = &oldsighand->siglock;

880
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
881 882 883 884 885 886
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
887
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
888 889 890 891 892 893 894
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
895

896
	sig->group_exit_task = tsk;
897 898 899
	sig->notify_count = zap_other_threads(tsk);
	if (!thread_group_leader(tsk))
		sig->notify_count--;
L
Linus Torvalds 已提交
900

901
	while (sig->notify_count) {
L
Linus Torvalds 已提交
902 903 904 905 906 907 908 909 910 911 912 913
		__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:
	 */
914
	if (!thread_group_leader(tsk)) {
915
		struct task_struct *leader = tsk->group_leader;
916

917
		sig->notify_count = -1;	/* for exit_notify() */
918 919 920 921 922 923 924 925
		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
926

927 928 929 930 931 932 933 934 935 936
		/*
		 * 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).
		 */
937
		tsk->start_time = leader->start_time;
938

939 940
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
941 942 943 944 945 946
		/*
		 * 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:
		 */
947 948

		/* Become a process group leader with the old leader's pid.
949 950
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
951 952
		 *       is called.  Odd but simple and correct.
		 */
953 954
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
955
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
956 957
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
958

959
		list_replace_rcu(&leader->tasks, &tsk->tasks);
960
		list_replace_init(&leader->sibling, &tsk->sibling);
L
Linus Torvalds 已提交
961

962 963
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
964

965
		tsk->exit_signal = SIGCHLD;
966 967 968

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
969
		write_unlock_irq(&tasklist_lock);
970 971

		release_task(leader);
972
	}
L
Linus Torvalds 已提交
973

974 975
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
976 977

no_thread_group:
J
Jiri Pirko 已提交
978 979 980
	if (current->mm)
		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);

L
Linus Torvalds 已提交
981
	exit_itimers(sig);
982
	flush_itimer_signals();
983

984 985
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
986
		/*
987 988
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
989
		 */
990 991 992 993
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
994 995 996 997 998 999
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
1000
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
1001 1002 1003
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

1004
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
1005 1006
	}

1007
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
1008 1009
	return 0;
}
O
Oleg Nesterov 已提交
1010

L
Linus Torvalds 已提交
1011 1012 1013 1014
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
1015
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
1016 1017
{
	long j = -1;
1018
	struct fdtable *fdt;
L
Linus Torvalds 已提交
1019 1020 1021 1022 1023 1024 1025

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

		j++;
		i = j * __NFDBITS;
1026
		fdt = files_fdtable(files);
1027
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
1028
			break;
1029
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
1030 1031
		if (!set)
			continue;
1032
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
		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);
}

1045
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
1046 1047 1048 1049 1050
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
1051
	return buf;
L
Linus Torvalds 已提交
1052
}
1053
EXPORT_SYMBOL_GPL(get_task_comm);
L
Linus Torvalds 已提交
1054 1055 1056 1057

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
1058 1059 1060 1061 1062 1063 1064 1065 1066

	/*
	 * 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
1067 1068
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
1069
	perf_event_comm(tsk);
L
Linus Torvalds 已提交
1070 1071 1072 1073
}

int flush_old_exec(struct linux_binprm * bprm)
{
1074
	int retval;
L
Linus Torvalds 已提交
1075 1076 1077 1078 1079 1080 1081 1082 1083

	/*
	 * 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
1084 1085
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
1086 1087 1088
	/*
	 * Release all of the old mmap stuff
	 */
1089
	acct_arg_size(bprm, 0);
L
Linus Torvalds 已提交
1090 1091
	retval = exec_mmap(bprm->mm);
	if (retval)
1092
		goto out;
L
Linus Torvalds 已提交
1093 1094

	bprm->mm = NULL;		/* We're using it now */
1095

1096
	current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1097 1098 1099
	flush_thread();
	current->personality &= ~bprm->per_clear;

1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
	return 0;

out:
	return retval;
}
EXPORT_SYMBOL(flush_old_exec);

void setup_new_exec(struct linux_binprm * bprm)
{
	int i, ch;
1110
	const char *name;
1111 1112 1113
	char tcomm[sizeof(current->comm)];

	arch_pick_mmap_layout(current->mm);
L
Linus Torvalds 已提交
1114 1115 1116 1117

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

1118
	if (current_euid() == current_uid() && current_egid() == current_gid())
1119
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
1120
	else
1121
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
1122

L
Linus Torvalds 已提交
1123
	name = bprm->filename;
1124 1125

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
1126 1127
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
1128
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
1129 1130 1131 1132 1133 1134 1135
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

1136 1137 1138 1139 1140 1141
	/* 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;

1142 1143 1144
	/* install the new credentials */
	if (bprm->cred->uid != current_euid() ||
	    bprm->cred->gid != current_egid()) {
1145 1146
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
1147
		   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1148
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1149 1150
	}

I
Ingo Molnar 已提交
1151 1152 1153 1154 1155
	/*
	 * Flush performance counters when crossing a
	 * security domain:
	 */
	if (!get_dumpable(current->mm))
1156
		perf_event_exit_task(current);
I
Ingo Molnar 已提交
1157

L
Linus Torvalds 已提交
1158 1159 1160 1161 1162 1163 1164 1165
	/* 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);
}
1166
EXPORT_SYMBOL(setup_new_exec);
L
Linus Torvalds 已提交
1167

1168 1169 1170 1171 1172 1173 1174 1175
/*
 * 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)
{
1176
	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1177 1178 1179 1180 1181 1182
		return -ERESTARTNOINTR;

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

1183
	mutex_unlock(&current->signal->cred_guard_mutex);
1184 1185 1186 1187 1188 1189 1190
	return -ENOMEM;
}

void free_bprm(struct linux_binprm *bprm)
{
	free_arg_pages(bprm);
	if (bprm->cred) {
1191
		mutex_unlock(&current->signal->cred_guard_mutex);
1192 1193 1194 1195 1196
		abort_creds(bprm->cred);
	}
	kfree(bprm);
}

1197 1198 1199 1200 1201 1202 1203 1204 1205
/*
 * 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;
1206 1207
	/*
	 * cred_guard_mutex must be held at least to this point to prevent
1208
	 * ptrace_attach() from altering our determination of the task's
1209 1210
	 * credentials; any time after this it may be unlocked.
	 */
1211
	security_bprm_committed_creds(bprm);
1212
	mutex_unlock(&current->signal->cred_guard_mutex);
1213 1214 1215 1216 1217
}
EXPORT_SYMBOL(install_exec_creds);

/*
 * determine how safe it is to execute the proposed program
1218
 * - the caller must hold ->cred_guard_mutex to protect against
1219 1220
 *   PTRACE_ATTACH
 */
A
Al Viro 已提交
1221
int check_unsafe_exec(struct linux_binprm *bprm)
1222
{
D
David Howells 已提交
1223
	struct task_struct *p = current, *t;
1224
	unsigned n_fs;
A
Al Viro 已提交
1225
	int res = 0;
1226 1227 1228

	bprm->unsafe = tracehook_unsafe_exec(p);

D
David Howells 已提交
1229
	n_fs = 1;
N
Nick Piggin 已提交
1230
	spin_lock(&p->fs->lock);
1231
	rcu_read_lock();
D
David Howells 已提交
1232 1233 1234 1235
	for (t = next_thread(p); t != p; t = next_thread(t)) {
		if (t->fs == p->fs)
			n_fs++;
	}
1236
	rcu_read_unlock();
D
David Howells 已提交
1237

1238
	if (p->fs->users > n_fs) {
1239
		bprm->unsafe |= LSM_UNSAFE_SHARE;
A
Al Viro 已提交
1240
	} else {
1241 1242 1243 1244 1245
		res = -EAGAIN;
		if (!p->fs->in_exec) {
			p->fs->in_exec = 1;
			res = 1;
		}
A
Al Viro 已提交
1246
	}
N
Nick Piggin 已提交
1247
	spin_unlock(&p->fs->lock);
A
Al Viro 已提交
1248 1249

	return res;
1250 1251
}

L
Linus Torvalds 已提交
1252 1253 1254
/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1255 1256
 *
 * This may be called multiple times for binary chains (scripts for example).
L
Linus Torvalds 已提交
1257 1258 1259
 */
int prepare_binprm(struct linux_binprm *bprm)
{
1260
	umode_t mode;
1261
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1262 1263 1264 1265 1266 1267
	int retval;

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

1268 1269 1270
	/* 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
1271

1272
	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1273 1274
		/* Set-uid? */
		if (mode & S_ISUID) {
1275 1276
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->euid = inode->i_uid;
L
Linus Torvalds 已提交
1277 1278 1279 1280 1281 1282 1283 1284 1285
		}

		/* 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)) {
1286 1287
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->egid = inode->i_gid;
L
Linus Torvalds 已提交
1288 1289 1290 1291
		}
	}

	/* fill in binprm security blob */
1292
	retval = security_bprm_set_creds(bprm);
L
Linus Torvalds 已提交
1293 1294
	if (retval)
		return retval;
1295
	bprm->cred_prepared = 1;
L
Linus Torvalds 已提交
1296

1297 1298
	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
L
Linus Torvalds 已提交
1299 1300 1301 1302
}

EXPORT_SYMBOL(prepare_binprm);

N
Nick Piggin 已提交
1303 1304 1305 1306 1307
/*
 * 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.
 */
1308
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1309
{
1310 1311 1312 1313
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1314

1315 1316
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1317

1318 1319 1320 1321 1322 1323 1324 1325
	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
1326

1327 1328 1329
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1330

1331 1332
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1333

1334 1335 1336
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1337

1338 1339 1340
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1341

1342 1343
out:
	return ret;
L
Linus Torvalds 已提交
1344 1345 1346 1347 1348 1349 1350 1351
}
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)
{
1352
	unsigned int depth = bprm->recursion_depth;
L
Linus Torvalds 已提交
1353 1354 1355 1356 1357 1358 1359 1360 1361 1362
	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
1363 1364 1365 1366 1367

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

L
Linus Torvalds 已提交
1368 1369 1370
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1371
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1372 1373 1374 1375 1376 1377 1378
			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);
1379 1380 1381 1382 1383 1384
			/*
			 * 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
1385
			if (retval >= 0) {
1386
				if (depth == 0)
T
Tejun Heo 已提交
1387
					ptrace_event(PTRACE_EVENT_EXEC, 0);
L
Linus Torvalds 已提交
1388 1389 1390 1391 1392 1393
				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
1394
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408
				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
1409 1410
#ifdef CONFIG_MODULES
		} else {
L
Linus Torvalds 已提交
1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428
#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.
 */
1429 1430 1431 1432
static int do_execve_common(const char *filename,
				struct user_arg_ptr argv,
				struct user_arg_ptr envp,
				struct pt_regs *regs)
L
Linus Torvalds 已提交
1433 1434 1435
{
	struct linux_binprm *bprm;
	struct file *file;
1436
	struct files_struct *displaced;
1437
	bool clear_in_exec;
L
Linus Torvalds 已提交
1438 1439
	int retval;

1440
	retval = unshare_files(&displaced);
1441 1442 1443
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1444
	retval = -ENOMEM;
1445
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1446
	if (!bprm)
1447
		goto out_files;
L
Linus Torvalds 已提交
1448

1449 1450
	retval = prepare_bprm_creds(bprm);
	if (retval)
1451
		goto out_free;
A
Al Viro 已提交
1452 1453

	retval = check_unsafe_exec(bprm);
1454
	if (retval < 0)
1455
		goto out_free;
1456
	clear_in_exec = retval;
1457
	current->in_execve = 1;
1458

L
Linus Torvalds 已提交
1459 1460 1461
	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
A
Al Viro 已提交
1462
		goto out_unmark;
L
Linus Torvalds 已提交
1463 1464 1465 1466 1467 1468 1469

	sched_exec();

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

1470 1471 1472
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1473

1474
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1475
	if ((retval = bprm->argc) < 0)
1476
		goto out;
L
Linus Torvalds 已提交
1477

1478
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499
	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;

	retval = search_binary_handler(bprm,regs);
1500 1501
	if (retval < 0)
		goto out;
L
Linus Torvalds 已提交
1502

1503
	/* execve succeeded */
A
Al Viro 已提交
1504
	current->fs->in_exec = 0;
1505
	current->in_execve = 0;
1506 1507 1508 1509 1510
	acct_update_integrals(current);
	free_bprm(bprm);
	if (displaced)
		put_files_struct(displaced);
	return retval;
L
Linus Torvalds 已提交
1511

1512
out:
1513 1514 1515 1516
	if (bprm->mm) {
		acct_arg_size(bprm, 0);
		mmput(bprm->mm);
	}
L
Linus Torvalds 已提交
1517 1518 1519 1520 1521 1522

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
1523

A
Al Viro 已提交
1524
out_unmark:
1525 1526
	if (clear_in_exec)
		current->fs->in_exec = 0;
1527
	current->in_execve = 0;
1528 1529

out_free:
1530
	free_bprm(bprm);
L
Linus Torvalds 已提交
1531

1532
out_files:
1533 1534
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1535 1536 1537 1538
out_ret:
	return retval;
}

1539 1540 1541 1542 1543
int do_execve(const char *filename,
	const char __user *const __user *__argv,
	const char __user *const __user *__envp,
	struct pt_regs *regs)
{
1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562
	struct user_arg_ptr argv = { .ptr.native = __argv };
	struct user_arg_ptr envp = { .ptr.native = __envp };
	return do_execve_common(filename, argv, envp, regs);
}

#ifdef CONFIG_COMPAT
int compat_do_execve(char *filename,
	compat_uptr_t __user *__argv,
	compat_uptr_t __user *__envp,
	struct pt_regs *regs)
{
	struct user_arg_ptr argv = {
		.is_compat = true,
		.ptr.compat = __argv,
	};
	struct user_arg_ptr envp = {
		.is_compat = true,
		.ptr.compat = __envp,
	};
1563 1564
	return do_execve_common(filename, argv, envp, regs);
}
1565
#endif
1566

1567
void set_binfmt(struct linux_binfmt *new)
L
Linus Torvalds 已提交
1568
{
1569 1570 1571 1572
	struct mm_struct *mm = current->mm;

	if (mm->binfmt)
		module_put(mm->binfmt->module);
L
Linus Torvalds 已提交
1573

1574
	mm->binfmt = new;
1575 1576
	if (new)
		__module_get(new->module);
L
Linus Torvalds 已提交
1577 1578 1579 1580
}

EXPORT_SYMBOL(set_binfmt);

1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625
static int expand_corename(struct core_name *cn)
{
	char *old_corename = cn->corename;

	cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
	cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);

	if (!cn->corename) {
		kfree(old_corename);
		return -ENOMEM;
	}

	return 0;
}

static int cn_printf(struct core_name *cn, const char *fmt, ...)
{
	char *cur;
	int need;
	int ret;
	va_list arg;

	va_start(arg, fmt);
	need = vsnprintf(NULL, 0, fmt, arg);
	va_end(arg);

	if (likely(need < cn->size - cn->used - 1))
		goto out_printf;

	ret = expand_corename(cn);
	if (ret)
		goto expand_fail;

out_printf:
	cur = cn->corename + cn->used;
	va_start(arg, fmt);
	vsnprintf(cur, need + 1, fmt, arg);
	va_end(arg);
	cn->used += need;
	return 0;

expand_fail:
	return ret;
}

1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660
static int cn_print_exe_file(struct core_name *cn)
{
	struct file *exe_file;
	char *pathbuf, *path, *p;
	int ret;

	exe_file = get_mm_exe_file(current->mm);
	if (!exe_file)
		return cn_printf(cn, "(unknown)");

	pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
	if (!pathbuf) {
		ret = -ENOMEM;
		goto put_exe_file;
	}

	path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
	if (IS_ERR(path)) {
		ret = PTR_ERR(path);
		goto free_buf;
	}

	for (p = path; *p; p++)
		if (*p == '/')
			*p = '!';

	ret = cn_printf(cn, "%s", path);

free_buf:
	kfree(pathbuf);
put_exe_file:
	fput(exe_file);
	return ret;
}

L
Linus Torvalds 已提交
1661 1662 1663 1664
/* 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.
 */
1665
static int format_corename(struct core_name *cn, long signr)
L
Linus Torvalds 已提交
1666
{
1667
	const struct cred *cred = current_cred();
1668 1669
	const char *pat_ptr = core_pattern;
	int ispipe = (*pat_ptr == '|');
L
Linus Torvalds 已提交
1670
	int pid_in_pattern = 0;
1671 1672 1673 1674 1675 1676 1677 1678
	int err = 0;

	cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
	cn->corename = kmalloc(cn->size, GFP_KERNEL);
	cn->used = 0;

	if (!cn->corename)
		return -ENOMEM;
L
Linus Torvalds 已提交
1679 1680 1681 1682 1683

	/* Repeat as long as we have more pattern to process and more output
	   space */
	while (*pat_ptr) {
		if (*pat_ptr != '%') {
1684
			if (*pat_ptr == 0)
L
Linus Torvalds 已提交
1685
				goto out;
1686
			err = cn_printf(cn, "%c", *pat_ptr++);
L
Linus Torvalds 已提交
1687 1688
		} else {
			switch (*++pat_ptr) {
1689
			/* single % at the end, drop that */
L
Linus Torvalds 已提交
1690 1691 1692 1693
			case 0:
				goto out;
			/* Double percent, output one percent */
			case '%':
1694
				err = cn_printf(cn, "%c", '%');
L
Linus Torvalds 已提交
1695 1696 1697 1698
				break;
			/* pid */
			case 'p':
				pid_in_pattern = 1;
1699 1700
				err = cn_printf(cn, "%d",
					      task_tgid_vnr(current));
L
Linus Torvalds 已提交
1701 1702 1703
				break;
			/* uid */
			case 'u':
1704
				err = cn_printf(cn, "%d", cred->uid);
L
Linus Torvalds 已提交
1705 1706 1707
				break;
			/* gid */
			case 'g':
1708
				err = cn_printf(cn, "%d", cred->gid);
L
Linus Torvalds 已提交
1709 1710 1711
				break;
			/* signal that caused the coredump */
			case 's':
1712
				err = cn_printf(cn, "%ld", signr);
L
Linus Torvalds 已提交
1713 1714 1715 1716 1717
				break;
			/* UNIX time of coredump */
			case 't': {
				struct timeval tv;
				do_gettimeofday(&tv);
1718
				err = cn_printf(cn, "%lu", tv.tv_sec);
L
Linus Torvalds 已提交
1719 1720 1721 1722 1723
				break;
			}
			/* hostname */
			case 'h':
				down_read(&uts_sem);
1724 1725
				err = cn_printf(cn, "%s",
					      utsname()->nodename);
L
Linus Torvalds 已提交
1726 1727 1728 1729
				up_read(&uts_sem);
				break;
			/* executable */
			case 'e':
1730
				err = cn_printf(cn, "%s", current->comm);
L
Linus Torvalds 已提交
1731
				break;
1732 1733 1734
			case 'E':
				err = cn_print_exe_file(cn);
				break;
1735 1736
			/* core limit size */
			case 'c':
1737 1738
				err = cn_printf(cn, "%lu",
					      rlimit(RLIMIT_CORE));
1739
				break;
L
Linus Torvalds 已提交
1740 1741 1742 1743 1744
			default:
				break;
			}
			++pat_ptr;
		}
1745 1746 1747

		if (err)
			return err;
L
Linus Torvalds 已提交
1748
	}
1749

L
Linus Torvalds 已提交
1750 1751 1752 1753
	/* 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
1754
	 * the filename. Do not do this for piped commands. */
1755
	if (!ispipe && !pid_in_pattern && core_uses_pid) {
1756 1757 1758
		err = cn_printf(cn, ".%d", task_tgid_vnr(current));
		if (err)
			return err;
L
Linus Torvalds 已提交
1759
	}
1760 1761
out:
	return ispipe;
L
Linus Torvalds 已提交
1762 1763
}

1764
static int zap_process(struct task_struct *start, int exit_code)
1765 1766
{
	struct task_struct *t;
1767
	int nr = 0;
1768

1769
	start->signal->flags = SIGNAL_GROUP_EXIT;
1770
	start->signal->group_exit_code = exit_code;
1771
	start->signal->group_stop_count = 0;
1772 1773 1774

	t = start;
	do {
1775
		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1776
		if (t != current && t->mm) {
1777 1778
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1779
			nr++;
1780
		}
1781
	} while_each_thread(start, t);
1782 1783

	return nr;
1784 1785
}

1786
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1787
				struct core_state *core_state, int exit_code)
L
Linus Torvalds 已提交
1788 1789
{
	struct task_struct *g, *p;
1790
	unsigned long flags;
1791
	int nr = -EAGAIN;
1792 1793

	spin_lock_irq(&tsk->sighand->siglock);
1794
	if (!signal_group_exit(tsk->signal)) {
1795
		mm->core_state = core_state;
1796
		nr = zap_process(tsk, exit_code);
L
Linus Torvalds 已提交
1797
	}
1798
	spin_unlock_irq(&tsk->sighand->siglock);
1799 1800
	if (unlikely(nr < 0))
		return nr;
L
Linus Torvalds 已提交
1801

1802
	if (atomic_read(&mm->mm_users) == nr + 1)
1803
		goto done;
1804 1805
	/*
	 * We should find and kill all tasks which use this mm, and we should
1806
	 * count them correctly into ->nr_threads. We don't take tasklist
1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833
	 * 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().
	 */
1834
	rcu_read_lock();
1835
	for_each_process(g) {
1836 1837
		if (g == tsk->group_leader)
			continue;
1838 1839
		if (g->flags & PF_KTHREAD)
			continue;
1840 1841 1842
		p = g;
		do {
			if (p->mm) {
1843
				if (unlikely(p->mm == mm)) {
1844
					lock_task_sighand(p, &flags);
1845
					nr += zap_process(p, exit_code);
1846 1847
					unlock_task_sighand(p, &flags);
				}
1848 1849
				break;
			}
1850
		} while_each_thread(g, p);
1851
	}
1852
	rcu_read_unlock();
1853
done:
1854
	atomic_set(&core_state->nr_threads, nr);
1855
	return nr;
L
Linus Torvalds 已提交
1856 1857
}

1858
static int coredump_wait(int exit_code, struct core_state *core_state)
L
Linus Torvalds 已提交
1859
{
1860 1861 1862
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion *vfork_done;
1863
	int core_waiters = -EBUSY;
L
Linus Torvalds 已提交
1864

1865
	init_completion(&core_state->startup);
1866 1867
	core_state->dumper.task = tsk;
	core_state->dumper.next = NULL;
1868 1869 1870 1871

	down_write(&mm->mmap_sem);
	if (!mm->core_state)
		core_waiters = zap_threads(tsk, mm, core_state, exit_code);
O
Oleg Nesterov 已提交
1872 1873
	up_write(&mm->mmap_sem);

1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
	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
1887
	if (core_waiters)
1888
		wait_for_completion(&core_state->startup);
1889 1890
fail:
	return core_waiters;
L
Linus Torvalds 已提交
1891 1892
}

O
Oleg Nesterov 已提交
1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913
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;
}

1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954
/*
 * 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;
	}
}

1955
static int __get_dumpable(unsigned long mm_flags)
1956 1957 1958
{
	int ret;

1959
	ret = mm_flags & MMF_DUMPABLE_MASK;
1960 1961 1962
	return (ret >= 2) ? 2 : ret;
}

1963 1964 1965 1966 1967
int get_dumpable(struct mm_struct *mm)
{
	return __get_dumpable(mm->flags);
}

1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990
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);

}


1991
/*
H
Holger Hans Peter Freyther 已提交
1992
 * umh_pipe_setup
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
 * helper function to customize the process used
 * to collect the core in userspace.  Specifically
 * it sets up a pipe and installs it as fd 0 (stdin)
 * for the process.  Returns 0 on success, or
 * PTR_ERR on failure.
 * Note that it also sets the core limit to 1.  This
 * is a special value that we use to trap recursive
 * core dumps
 */
static int umh_pipe_setup(struct subprocess_info *info)
{
	struct file *rp, *wp;
	struct fdtable *fdt;
	struct coredump_params *cp = (struct coredump_params *)info->data;
	struct files_struct *cf = current->files;

	wp = create_write_pipe(0);
	if (IS_ERR(wp))
		return PTR_ERR(wp);

	rp = create_read_pipe(wp, 0);
	if (IS_ERR(rp)) {
		free_write_pipe(wp);
		return PTR_ERR(rp);
	}

	cp->file = wp;

	sys_close(0);
	fd_install(0, rp);
	spin_lock(&cf->file_lock);
	fdt = files_fdtable(cf);
	FD_SET(0, fdt->open_fds);
	FD_CLR(0, fdt->close_on_exec);
	spin_unlock(&cf->file_lock);

	/* and disallow core files too */
	current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};

	return 0;
}

W
WANG Cong 已提交
2035
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
L
Linus Torvalds 已提交
2036
{
2037
	struct core_state core_state;
2038
	struct core_name cn;
L
Linus Torvalds 已提交
2039 2040
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
D
David Howells 已提交
2041 2042
	const struct cred *old_cred;
	struct cred *cred;
L
Linus Torvalds 已提交
2043
	int retval = 0;
A
Alan Cox 已提交
2044
	int flag = 0;
O
Oleg Nesterov 已提交
2045
	int ispipe;
2046
	static atomic_t core_dump_count = ATOMIC_INIT(0);
2047 2048 2049
	struct coredump_params cprm = {
		.signr = signr,
		.regs = regs,
J
Jiri Slaby 已提交
2050
		.limit = rlimit(RLIMIT_CORE),
2051 2052 2053 2054 2055 2056
		/*
		 * We must use the same mm->flags while dumping core to avoid
		 * inconsistency of bit flags, since this flag is not protected
		 * by any locks.
		 */
		.mm_flags = mm->flags,
2057
	};
L
Linus Torvalds 已提交
2058

S
Steve Grubb 已提交
2059 2060
	audit_core_dumps(signr);

2061
	binfmt = mm->binfmt;
L
Linus Torvalds 已提交
2062 2063
	if (!binfmt || !binfmt->core_dump)
		goto fail;
2064 2065
	if (!__get_dumpable(cprm.mm_flags))
		goto fail;
D
David Howells 已提交
2066 2067

	cred = prepare_creds();
2068
	if (!cred)
D
David Howells 已提交
2069
		goto fail;
A
Alan Cox 已提交
2070 2071 2072 2073 2074
	/*
	 *	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.
	 */
2075 2076
	if (__get_dumpable(cprm.mm_flags) == 2) {
		/* Setuid core dump mode */
A
Alan Cox 已提交
2077
		flag = O_EXCL;		/* Stop rewrite attacks */
D
David Howells 已提交
2078
		cred->fsuid = 0;	/* Dump root private */
A
Alan Cox 已提交
2079
	}
2080

2081
	retval = coredump_wait(exit_code, &core_state);
2082 2083
	if (retval < 0)
		goto fail_creds;
D
David Howells 已提交
2084 2085

	old_cred = override_creds(cred);
L
Linus Torvalds 已提交
2086 2087 2088 2089 2090 2091 2092

	/*
	 * 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);

2093 2094 2095 2096 2097 2098 2099
	ispipe = format_corename(&cn, signr);

	if (ispipe == -ENOMEM) {
		printk(KERN_WARNING "format_corename failed\n");
		printk(KERN_WARNING "Aborting core\n");
		goto fail_corename;
	}
2100

2101
 	if (ispipe) {
O
Oleg Nesterov 已提交
2102 2103 2104
		int dump_count;
		char **helper_argv;

2105
		if (cprm.limit == 1) {
2106 2107 2108
			/*
			 * Normally core limits are irrelevant to pipes, since
			 * we're not writing to the file system, but we use
2109 2110
			 * cprm.limit of 1 here as a speacial value. Any
			 * non-1 limit gets set to RLIM_INFINITY below, but
2111 2112
			 * a limit of 0 skips the dump.  This is a consistent
			 * way to catch recursive crashes.  We can still crash
2113
			 * if the core_pattern binary sets RLIM_CORE =  !1
2114 2115 2116 2117 2118 2119 2120
			 * 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
2121
				"Process %d(%s) has RLIMIT_CORE set to 1\n",
2122 2123 2124 2125
				task_tgid_vnr(current), current->comm);
			printk(KERN_WARNING "Aborting core\n");
			goto fail_unlock;
		}
O
Oleg Nesterov 已提交
2126
		cprm.limit = RLIM_INFINITY;
2127

2128 2129 2130 2131 2132 2133 2134 2135
		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;
		}

2136
		helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2137 2138 2139
		if (!helper_argv) {
			printk(KERN_WARNING "%s failed to allocate memory\n",
			       __func__);
2140
			goto fail_dropcount;
2141
		}
2142

O
Oleg Nesterov 已提交
2143 2144 2145 2146 2147
		retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
					NULL, UMH_WAIT_EXEC, umh_pipe_setup,
					NULL, &cprm);
		argv_free(helper_argv);
		if (retval) {
2148
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
2149
			       cn.corename);
O
Oleg Nesterov 已提交
2150
			goto close_fail;
2151
 		}
2152 2153 2154 2155 2156 2157
	} else {
		struct inode *inode;

		if (cprm.limit < binfmt->min_coredump)
			goto fail_unlock;

2158
		cprm.file = filp_open(cn.corename,
2159 2160
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
2161 2162
		if (IS_ERR(cprm.file))
			goto fail_unlock;
L
Linus Torvalds 已提交
2163

2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185
		inode = cprm.file->f_path.dentry->d_inode;
		if (inode->i_nlink > 1)
			goto close_fail;
		if (d_unhashed(cprm.file->f_path.dentry))
			goto close_fail;
		/*
		 * AK: actually i see no reason to not allow this for named
		 * pipes etc, but keep the previous behaviour for now.
		 */
		if (!S_ISREG(inode->i_mode))
			goto close_fail;
		/*
		 * Dont allow local users get cute and trick others to coredump
		 * into their pre-created files.
		 */
		if (inode->i_uid != current_fsuid())
			goto close_fail;
		if (!cprm.file->f_op || !cprm.file->f_op->write)
			goto close_fail;
		if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
			goto close_fail;
	}
L
Linus Torvalds 已提交
2186

2187
	retval = binfmt->core_dump(&cprm);
L
Linus Torvalds 已提交
2188 2189
	if (retval)
		current->signal->group_exit_code |= 0x80;
O
Oleg Nesterov 已提交
2190

2191
	if (ispipe && core_pipe_limit)
2192
		wait_for_dump_helpers(cprm.file);
O
Oleg Nesterov 已提交
2193 2194 2195
close_fail:
	if (cprm.file)
		filp_close(cprm.file, NULL);
2196
fail_dropcount:
O
Oleg Nesterov 已提交
2197
	if (ispipe)
2198
		atomic_dec(&core_dump_count);
L
Linus Torvalds 已提交
2199
fail_unlock:
2200 2201
	kfree(cn.corename);
fail_corename:
2202
	coredump_finish(mm);
D
David Howells 已提交
2203
	revert_creds(old_cred);
2204
fail_creds:
D
David Howells 已提交
2205
	put_cred(cred);
L
Linus Torvalds 已提交
2206
fail:
W
WANG Cong 已提交
2207
	return;
L
Linus Torvalds 已提交
2208
}
2209 2210 2211 2212 2213 2214 2215 2216 2217 2218

/*
 * Core dumping helper functions.  These are the only things you should
 * do on a core-file: use only these functions to write out all the
 * necessary info.
 */
int dump_write(struct file *file, const void *addr, int nr)
{
	return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
}
2219
EXPORT_SYMBOL(dump_write);
2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247

int dump_seek(struct file *file, loff_t off)
{
	int ret = 1;

	if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
		if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
			return 0;
	} else {
		char *buf = (char *)get_zeroed_page(GFP_KERNEL);

		if (!buf)
			return 0;
		while (off > 0) {
			unsigned long n = off;

			if (n > PAGE_SIZE)
				n = PAGE_SIZE;
			if (!dump_write(file, buf, n)) {
				ret = 0;
				break;
			}
			off -= n;
		}
		free_page((unsigned long)buf);
	}
	return ret;
}
2248
EXPORT_SYMBOL(dump_seek);