exec.c 46.6 KB
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/*
 *  linux/fs/exec.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

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

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

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

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

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

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

EXPORT_SYMBOL(unregister_binfmt);

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

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

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	if (IS_ERR(tmp))
		goto out;

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

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

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

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	fsnotify_open(file->f_path.dentry);

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

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

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#ifdef CONFIG_MMU

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

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

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

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

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

	return 0;
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}

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/*
 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
 * the stack is optionally relocated, and some extra space is added.
 */
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int setup_arg_pages(struct linux_binprm *bprm,
		    unsigned long stack_top,
		    int executable_stack)
{
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	unsigned long ret;
	unsigned long stack_shift;
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	struct mm_struct *mm = current->mm;
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	struct vm_area_struct *vma = bprm->vma;
	struct vm_area_struct *prev = NULL;
	unsigned long vm_flags;
	unsigned long stack_base;
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	unsigned long stack_size;
	unsigned long stack_expand;
	unsigned long rlim_stack;
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#ifdef CONFIG_STACK_GROWSUP
	/* Limit stack size to 1GB */
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	stack_base = rlimit_max(RLIMIT_STACK);
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	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;
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	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
621 622 623 624 625 626 627 628 629 630

	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);
631 632
		if (ret)
			goto out_unlock;
L
Linus Torvalds 已提交
633 634
	}

635 636 637
	/* mprotect_fixup is overkill to remove the temporary stack flags */
	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;

638
	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
639 640 641 642 643 644
	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;
645
#ifdef CONFIG_STACK_GROWSUP
646 647 648 649
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_start + rlim_stack;
	else
		stack_base = vma->vm_end + stack_expand;
650
#else
651 652 653 654
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_end - rlim_stack;
	else
		stack_base = vma->vm_start - stack_expand;
655 656 657 658 659 660
#endif
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
L
Linus Torvalds 已提交
661
	up_write(&mm->mmap_sem);
662
	return ret;
L
Linus Torvalds 已提交
663 664 665 666 667 668 669 670
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct file *file;
671
	int err;
L
Linus Torvalds 已提交
672

673 674 675 676
	file = do_filp_open(AT_FDCWD, name,
				O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
				MAY_EXEC | MAY_OPEN);
	if (IS_ERR(file))
677 678 679
		goto out;

	err = -EACCES;
680 681
	if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
		goto exit;
682

683 684
	if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
		goto exit;
685

686 687
	fsnotify_open(file->f_path.dentry);

688
	err = deny_write_access(file);
689 690
	if (err)
		goto exit;
L
Linus Torvalds 已提交
691

692
out:
693 694
	return file;

695 696
exit:
	fput(file);
697 698
	return ERR_PTR(err);
}
L
Linus Torvalds 已提交
699 700
EXPORT_SYMBOL(open_exec);

M
Mimi Zohar 已提交
701 702
int kernel_read(struct file *file, loff_t offset,
		char *addr, unsigned long count)
L
Linus Torvalds 已提交
703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725
{
	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;
726
	sync_mm_rss(tsk, old_mm);
L
Linus Torvalds 已提交
727 728 729 730 731 732 733
	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
734
		 * checking core_state and changing tsk->mm.
L
Linus Torvalds 已提交
735 736
		 */
		down_read(&old_mm->mmap_sem);
737
		if (unlikely(old_mm->core_state)) {
L
Linus Torvalds 已提交
738 739 740 741 742 743 744 745 746 747 748 749 750
			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);
751
		BUG_ON(active_mm != old_mm);
752
		mm_update_next_owner(old_mm);
L
Linus Torvalds 已提交
753 754 755 756 757 758 759 760 761 762 763 764 765
		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().)
 */
766
static int de_thread(struct task_struct *tsk)
L
Linus Torvalds 已提交
767 768
{
	struct signal_struct *sig = tsk->signal;
769
	struct sighand_struct *oldsighand = tsk->sighand;
L
Linus Torvalds 已提交
770 771 772
	spinlock_t *lock = &oldsighand->siglock;
	int count;

773
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
774 775 776 777 778 779
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
780
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
781 782 783 784 785 786 787
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
788
	sig->group_exit_task = tsk;
789
	zap_other_threads(tsk);
L
Linus Torvalds 已提交
790

791 792
	/* Account for the thread group leader hanging around: */
	count = thread_group_leader(tsk) ? 1 : 2;
793
	sig->notify_count = count;
L
Linus Torvalds 已提交
794 795 796 797 798 799 800 801 802 803 804 805 806
	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:
	 */
807
	if (!thread_group_leader(tsk)) {
808
		struct task_struct *leader = tsk->group_leader;
809

810
		sig->notify_count = -1;	/* for exit_notify() */
811 812 813 814 815 816 817 818
		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
819

820 821 822 823 824 825 826 827 828 829
		/*
		 * 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).
		 */
830
		tsk->start_time = leader->start_time;
831

832 833
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
834 835 836 837 838 839
		/*
		 * 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:
		 */
840 841

		/* Become a process group leader with the old leader's pid.
842 843
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
844 845
		 *       is called.  Odd but simple and correct.
		 */
846 847
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
848
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
849 850
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
851

852
		list_replace_rcu(&leader->tasks, &tsk->tasks);
853
		list_replace_init(&leader->sibling, &tsk->sibling);
L
Linus Torvalds 已提交
854

855 856
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
857

858
		tsk->exit_signal = SIGCHLD;
859 860 861

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
862
		write_unlock_irq(&tasklist_lock);
863 864

		release_task(leader);
865
	}
L
Linus Torvalds 已提交
866

867 868
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
869 870

no_thread_group:
J
Jiri Pirko 已提交
871 872 873
	if (current->mm)
		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);

L
Linus Torvalds 已提交
874
	exit_itimers(sig);
875
	flush_itimer_signals();
876

877 878
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
879
		/*
880 881
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
882
		 */
883 884 885 886
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
887 888 889 890 891 892
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
893
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
894 895 896
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

897
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
898 899
	}

900
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
901 902
	return 0;
}
O
Oleg Nesterov 已提交
903

L
Linus Torvalds 已提交
904 905 906 907
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
908
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
909 910
{
	long j = -1;
911
	struct fdtable *fdt;
L
Linus Torvalds 已提交
912 913 914 915 916 917 918

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

		j++;
		i = j * __NFDBITS;
919
		fdt = files_fdtable(files);
920
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
921
			break;
922
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
923 924
		if (!set)
			continue;
925
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
926 927 928 929 930 931 932 933 934 935 936 937
		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);
}

938
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
939 940 941 942 943
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
944
	return buf;
L
Linus Torvalds 已提交
945 946 947 948 949
}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
950 951 952 953 954 955 956 957 958

	/*
	 * 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
959 960
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
961
	perf_event_comm(tsk);
L
Linus Torvalds 已提交
962 963 964 965
}

int flush_old_exec(struct linux_binprm * bprm)
{
966
	int retval;
L
Linus Torvalds 已提交
967 968 969 970 971 972 973 974 975

	/*
	 * 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
976 977
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
978 979 980 981 982
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
983
		goto out;
L
Linus Torvalds 已提交
984 985

	bprm->mm = NULL;		/* We're using it now */
986 987 988 989 990

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

991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004
	return 0;

out:
	return retval;
}
EXPORT_SYMBOL(flush_old_exec);

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

	arch_pick_mmap_layout(current->mm);
L
Linus Torvalds 已提交
1005 1006 1007 1008

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

1009
	if (current_euid() == current_uid() && current_egid() == current_gid())
1010
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
1011
	else
1012
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
1013

L
Linus Torvalds 已提交
1014
	name = bprm->filename;
1015 1016

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
1017 1018
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
1019
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
1020 1021 1022 1023 1024 1025 1026
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

1027 1028 1029 1030 1031 1032
	/* 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;

1033 1034 1035
	/* install the new credentials */
	if (bprm->cred->uid != current_euid() ||
	    bprm->cred->gid != current_egid()) {
1036 1037
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
1038
		   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1039
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1040 1041
	}

I
Ingo Molnar 已提交
1042 1043 1044 1045 1046
	/*
	 * Flush performance counters when crossing a
	 * security domain:
	 */
	if (!get_dumpable(current->mm))
1047
		perf_event_exit_task(current);
I
Ingo Molnar 已提交
1048

L
Linus Torvalds 已提交
1049 1050 1051 1052 1053 1054 1055 1056
	/* 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);
}
1057
EXPORT_SYMBOL(setup_new_exec);
L
Linus Torvalds 已提交
1058

1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
/*
 * 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);
}

1088 1089 1090 1091 1092 1093 1094 1095 1096
/*
 * 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;
1097 1098
	/*
	 * cred_guard_mutex must be held at least to this point to prevent
1099
	 * ptrace_attach() from altering our determination of the task's
1100 1101
	 * credentials; any time after this it may be unlocked.
	 */
1102
	security_bprm_committed_creds(bprm);
1103
	mutex_unlock(&current->cred_guard_mutex);
1104 1105 1106 1107 1108
}
EXPORT_SYMBOL(install_exec_creds);

/*
 * determine how safe it is to execute the proposed program
1109
 * - the caller must hold current->cred_guard_mutex to protect against
1110 1111
 *   PTRACE_ATTACH
 */
A
Al Viro 已提交
1112
int check_unsafe_exec(struct linux_binprm *bprm)
1113
{
D
David Howells 已提交
1114
	struct task_struct *p = current, *t;
1115
	unsigned n_fs;
A
Al Viro 已提交
1116
	int res = 0;
1117 1118 1119

	bprm->unsafe = tracehook_unsafe_exec(p);

D
David Howells 已提交
1120
	n_fs = 1;
A
Al Viro 已提交
1121
	write_lock(&p->fs->lock);
1122
	rcu_read_lock();
D
David Howells 已提交
1123 1124 1125 1126
	for (t = next_thread(p); t != p; t = next_thread(t)) {
		if (t->fs == p->fs)
			n_fs++;
	}
1127
	rcu_read_unlock();
D
David Howells 已提交
1128

1129
	if (p->fs->users > n_fs) {
1130
		bprm->unsafe |= LSM_UNSAFE_SHARE;
A
Al Viro 已提交
1131
	} else {
1132 1133 1134 1135 1136
		res = -EAGAIN;
		if (!p->fs->in_exec) {
			p->fs->in_exec = 1;
			res = 1;
		}
A
Al Viro 已提交
1137 1138 1139 1140
	}
	write_unlock(&p->fs->lock);

	return res;
1141 1142
}

L
Linus Torvalds 已提交
1143 1144 1145
/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1146 1147
 *
 * This may be called multiple times for binary chains (scripts for example).
L
Linus Torvalds 已提交
1148 1149 1150
 */
int prepare_binprm(struct linux_binprm *bprm)
{
1151
	umode_t mode;
1152
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1153 1154 1155 1156 1157 1158
	int retval;

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

1159 1160 1161
	/* 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
1162

1163
	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1164 1165
		/* Set-uid? */
		if (mode & S_ISUID) {
1166 1167
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->euid = inode->i_uid;
L
Linus Torvalds 已提交
1168 1169 1170 1171 1172 1173 1174 1175 1176
		}

		/* 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)) {
1177 1178
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->egid = inode->i_gid;
L
Linus Torvalds 已提交
1179 1180 1181 1182
		}
	}

	/* fill in binprm security blob */
1183
	retval = security_bprm_set_creds(bprm);
L
Linus Torvalds 已提交
1184 1185
	if (retval)
		return retval;
1186
	bprm->cred_prepared = 1;
L
Linus Torvalds 已提交
1187

1188 1189
	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
L
Linus Torvalds 已提交
1190 1191 1192 1193
}

EXPORT_SYMBOL(prepare_binprm);

N
Nick Piggin 已提交
1194 1195 1196 1197 1198
/*
 * 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.
 */
1199
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1200
{
1201 1202 1203 1204
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1205

1206 1207
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1208

1209 1210 1211 1212 1213 1214 1215 1216
	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
1217

1218 1219 1220
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1221

1222 1223
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1224

1225 1226 1227
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1228

1229 1230 1231
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1232

1233 1234
out:
	return ret;
L
Linus Torvalds 已提交
1235 1236 1237 1238 1239 1240 1241 1242
}
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)
{
1243
	unsigned int depth = bprm->recursion_depth;
L
Linus Torvalds 已提交
1244 1245 1246 1247 1248 1249 1250 1251 1252 1253
	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
1254 1255 1256 1257 1258

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

L
Linus Torvalds 已提交
1259 1260 1261
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1262
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1263 1264 1265 1266 1267 1268 1269
			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);
1270 1271 1272 1273 1274 1275
			/*
			 * 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
1276
			if (retval >= 0) {
1277 1278
				if (depth == 0)
					tracehook_report_exec(fmt, bprm, regs);
L
Linus Torvalds 已提交
1279 1280 1281 1282 1283 1284
				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
1285
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299
				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
1300 1301
#ifdef CONFIG_MODULES
		} else {
L
Linus Torvalds 已提交
1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326
#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;
1327
	struct files_struct *displaced;
1328
	bool clear_in_exec;
L
Linus Torvalds 已提交
1329 1330
	int retval;

1331
	retval = unshare_files(&displaced);
1332 1333 1334
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1335
	retval = -ENOMEM;
1336
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1337
	if (!bprm)
1338
		goto out_files;
L
Linus Torvalds 已提交
1339

1340 1341
	retval = prepare_bprm_creds(bprm);
	if (retval)
1342
		goto out_free;
A
Al Viro 已提交
1343 1344

	retval = check_unsafe_exec(bprm);
1345
	if (retval < 0)
1346
		goto out_free;
1347
	clear_in_exec = retval;
1348
	current->in_execve = 1;
1349

L
Linus Torvalds 已提交
1350 1351 1352
	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
A
Al Viro 已提交
1353
		goto out_unmark;
L
Linus Torvalds 已提交
1354 1355 1356 1357 1358 1359 1360

	sched_exec();

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

1361 1362 1363
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1364

1365
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1366
	if ((retval = bprm->argc) < 0)
1367
		goto out;
L
Linus Torvalds 已提交
1368

1369
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389
	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
1390
	current->flags &= ~PF_KTHREAD;
L
Linus Torvalds 已提交
1391
	retval = search_binary_handler(bprm,regs);
1392 1393
	if (retval < 0)
		goto out;
L
Linus Torvalds 已提交
1394

1395
	/* execve succeeded */
A
Al Viro 已提交
1396
	current->fs->in_exec = 0;
1397
	current->in_execve = 0;
1398 1399 1400 1401 1402
	acct_update_integrals(current);
	free_bprm(bprm);
	if (displaced)
		put_files_struct(displaced);
	return retval;
L
Linus Torvalds 已提交
1403

1404
out:
L
Linus Torvalds 已提交
1405
	if (bprm->mm)
1406
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1407 1408 1409 1410 1411 1412

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
1413

A
Al Viro 已提交
1414
out_unmark:
1415 1416
	if (clear_in_exec)
		current->fs->in_exec = 0;
1417
	current->in_execve = 0;
1418 1419

out_free:
1420
	free_bprm(bprm);
L
Linus Torvalds 已提交
1421

1422
out_files:
1423 1424
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1425 1426 1427 1428
out_ret:
	return retval;
}

1429
void set_binfmt(struct linux_binfmt *new)
L
Linus Torvalds 已提交
1430
{
1431 1432 1433 1434
	struct mm_struct *mm = current->mm;

	if (mm->binfmt)
		module_put(mm->binfmt->module);
L
Linus Torvalds 已提交
1435

1436
	mm->binfmt = new;
1437 1438
	if (new)
		__module_get(new->module);
L
Linus Torvalds 已提交
1439 1440 1441 1442 1443 1444 1445 1446
}

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.
 */
1447
static int format_corename(char *corename, long signr)
L
Linus Torvalds 已提交
1448
{
1449
	const struct cred *cred = current_cred();
1450 1451
	const char *pat_ptr = core_pattern;
	int ispipe = (*pat_ptr == '|');
L
Linus Torvalds 已提交
1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477
	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,
1478
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1479 1480 1481 1482 1483 1484 1485
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
1486
					      "%d", cred->uid);
L
Linus Torvalds 已提交
1487 1488 1489 1490 1491 1492 1493
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
1494
					      "%d", cred->gid);
L
Linus Torvalds 已提交
1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521
				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,
1522
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535
				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;
1536 1537 1538
			/* core limit size */
			case 'c':
				rc = snprintf(out_ptr, out_end - out_ptr,
J
Jiri Slaby 已提交
1539
					      "%lu", rlimit(RLIMIT_CORE));
1540 1541 1542 1543
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
L
Linus Torvalds 已提交
1544 1545 1546 1547 1548 1549 1550 1551 1552 1553
			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
1554
	 * the filename. Do not do this for piped commands. */
1555
	if (!ispipe && !pid_in_pattern && core_uses_pid) {
L
Linus Torvalds 已提交
1556
		rc = snprintf(out_ptr, out_end - out_ptr,
1557
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1558 1559 1560 1561
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1562
out:
L
Linus Torvalds 已提交
1563
	*out_ptr = 0;
1564
	return ispipe;
L
Linus Torvalds 已提交
1565 1566
}

1567
static int zap_process(struct task_struct *start, int exit_code)
1568 1569
{
	struct task_struct *t;
1570
	int nr = 0;
1571

1572
	start->signal->flags = SIGNAL_GROUP_EXIT;
1573
	start->signal->group_exit_code = exit_code;
1574
	start->signal->group_stop_count = 0;
1575 1576 1577 1578

	t = start;
	do {
		if (t != current && t->mm) {
1579 1580
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1581
			nr++;
1582
		}
1583
	} while_each_thread(start, t);
1584 1585

	return nr;
1586 1587
}

1588
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1589
				struct core_state *core_state, int exit_code)
L
Linus Torvalds 已提交
1590 1591
{
	struct task_struct *g, *p;
1592
	unsigned long flags;
1593
	int nr = -EAGAIN;
1594 1595

	spin_lock_irq(&tsk->sighand->siglock);
1596
	if (!signal_group_exit(tsk->signal)) {
1597
		mm->core_state = core_state;
1598
		nr = zap_process(tsk, exit_code);
L
Linus Torvalds 已提交
1599
	}
1600
	spin_unlock_irq(&tsk->sighand->siglock);
1601 1602
	if (unlikely(nr < 0))
		return nr;
L
Linus Torvalds 已提交
1603

1604
	if (atomic_read(&mm->mm_users) == nr + 1)
1605
		goto done;
1606 1607
	/*
	 * We should find and kill all tasks which use this mm, and we should
1608
	 * count them correctly into ->nr_threads. We don't take tasklist
1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635
	 * 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().
	 */
1636
	rcu_read_lock();
1637
	for_each_process(g) {
1638 1639
		if (g == tsk->group_leader)
			continue;
1640 1641
		if (g->flags & PF_KTHREAD)
			continue;
1642 1643 1644
		p = g;
		do {
			if (p->mm) {
1645
				if (unlikely(p->mm == mm)) {
1646
					lock_task_sighand(p, &flags);
1647
					nr += zap_process(p, exit_code);
1648 1649
					unlock_task_sighand(p, &flags);
				}
1650 1651
				break;
			}
1652
		} while_each_thread(g, p);
1653
	}
1654
	rcu_read_unlock();
1655
done:
1656
	atomic_set(&core_state->nr_threads, nr);
1657
	return nr;
L
Linus Torvalds 已提交
1658 1659
}

1660
static int coredump_wait(int exit_code, struct core_state *core_state)
L
Linus Torvalds 已提交
1661
{
1662 1663 1664
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion *vfork_done;
O
Oleg Nesterov 已提交
1665
	int core_waiters;
L
Linus Torvalds 已提交
1666

1667
	init_completion(&core_state->startup);
1668 1669
	core_state->dumper.task = tsk;
	core_state->dumper.next = NULL;
1670
	core_waiters = zap_threads(tsk, mm, core_state, exit_code);
O
Oleg Nesterov 已提交
1671 1672
	up_write(&mm->mmap_sem);

1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685
	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
1686
	if (core_waiters)
1687
		wait_for_completion(&core_state->startup);
1688 1689
fail:
	return core_waiters;
L
Linus Torvalds 已提交
1690 1691
}

O
Oleg Nesterov 已提交
1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712
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;
}

1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753
/*
 * 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;
	}
}

1754
static int __get_dumpable(unsigned long mm_flags)
1755 1756 1757
{
	int ret;

1758
	ret = mm_flags & MMF_DUMPABLE_MASK;
1759 1760 1761
	return (ret >= 2) ? 2 : ret;
}

1762 1763 1764 1765 1766
int get_dumpable(struct mm_struct *mm)
{
	return __get_dumpable(mm->flags);
}

1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789
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);

}


1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 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
/*
 * uhm_pipe_setup
 * 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
1834
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
L
Linus Torvalds 已提交
1835
{
1836
	struct core_state core_state;
L
Linus Torvalds 已提交
1837 1838 1839
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
D
David Howells 已提交
1840 1841
	const struct cred *old_cred;
	struct cred *cred;
L
Linus Torvalds 已提交
1842
	int retval = 0;
A
Alan Cox 已提交
1843
	int flag = 0;
O
Oleg Nesterov 已提交
1844
	int ispipe;
1845
	static atomic_t core_dump_count = ATOMIC_INIT(0);
1846 1847 1848
	struct coredump_params cprm = {
		.signr = signr,
		.regs = regs,
J
Jiri Slaby 已提交
1849
		.limit = rlimit(RLIMIT_CORE),
1850 1851 1852 1853 1854 1855
		/*
		 * 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,
1856
	};
L
Linus Torvalds 已提交
1857

S
Steve Grubb 已提交
1858 1859
	audit_core_dumps(signr);

1860
	binfmt = mm->binfmt;
L
Linus Torvalds 已提交
1861 1862
	if (!binfmt || !binfmt->core_dump)
		goto fail;
D
David Howells 已提交
1863 1864

	cred = prepare_creds();
1865
	if (!cred)
D
David Howells 已提交
1866 1867
		goto fail;

L
Linus Torvalds 已提交
1868
	down_write(&mm->mmap_sem);
R
Roland McGrath 已提交
1869 1870 1871
	/*
	 * If another thread got here first, or we are not dumpable, bail out.
	 */
1872
	if (mm->core_state || !__get_dumpable(cprm.mm_flags)) {
L
Linus Torvalds 已提交
1873
		up_write(&mm->mmap_sem);
1874
		goto fail_creds;
L
Linus Torvalds 已提交
1875
	}
A
Alan Cox 已提交
1876 1877 1878 1879 1880 1881

	/*
	 *	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.
	 */
1882 1883
	if (__get_dumpable(cprm.mm_flags) == 2) {
		/* Setuid core dump mode */
A
Alan Cox 已提交
1884
		flag = O_EXCL;		/* Stop rewrite attacks */
D
David Howells 已提交
1885
		cred->fsuid = 0;	/* Dump root private */
A
Alan Cox 已提交
1886
	}
1887

1888
	retval = coredump_wait(exit_code, &core_state);
1889 1890
	if (retval < 0)
		goto fail_creds;
D
David Howells 已提交
1891 1892

	old_cred = override_creds(cred);
L
Linus Torvalds 已提交
1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904

	/*
	 * 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();
1905
	ispipe = format_corename(corename, signr);
L
Linus Torvalds 已提交
1906
	unlock_kernel();
1907

1908
 	if (ispipe) {
O
Oleg Nesterov 已提交
1909 1910 1911
		int dump_count;
		char **helper_argv;

1912
		if (cprm.limit == 1) {
1913 1914 1915
			/*
			 * Normally core limits are irrelevant to pipes, since
			 * we're not writing to the file system, but we use
1916 1917
			 * cprm.limit of 1 here as a speacial value. Any
			 * non-1 limit gets set to RLIM_INFINITY below, but
1918 1919
			 * a limit of 0 skips the dump.  This is a consistent
			 * way to catch recursive crashes.  We can still crash
1920
			 * if the core_pattern binary sets RLIM_CORE =  !1
1921 1922 1923 1924 1925 1926 1927
			 * 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
1928
				"Process %d(%s) has RLIMIT_CORE set to 1\n",
1929 1930 1931 1932
				task_tgid_vnr(current), current->comm);
			printk(KERN_WARNING "Aborting core\n");
			goto fail_unlock;
		}
O
Oleg Nesterov 已提交
1933
		cprm.limit = RLIM_INFINITY;
1934

1935 1936 1937 1938 1939 1940 1941 1942
		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;
		}

O
Oleg Nesterov 已提交
1943
		helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
1944 1945 1946
		if (!helper_argv) {
			printk(KERN_WARNING "%s failed to allocate memory\n",
			       __func__);
1947
			goto fail_dropcount;
1948
		}
1949

O
Oleg Nesterov 已提交
1950 1951 1952 1953 1954
		retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
					NULL, UMH_WAIT_EXEC, umh_pipe_setup,
					NULL, &cprm);
		argv_free(helper_argv);
		if (retval) {
1955 1956
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
O
Oleg Nesterov 已提交
1957
			goto close_fail;
1958
 		}
1959 1960 1961 1962 1963 1964
	} else {
		struct inode *inode;

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

1965
		cprm.file = filp_open(corename,
1966 1967
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
1968 1969
		if (IS_ERR(cprm.file))
			goto fail_unlock;
L
Linus Torvalds 已提交
1970

1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992
		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
1993

1994
	retval = binfmt->core_dump(&cprm);
L
Linus Torvalds 已提交
1995 1996
	if (retval)
		current->signal->group_exit_code |= 0x80;
O
Oleg Nesterov 已提交
1997

1998
	if (ispipe && core_pipe_limit)
1999
		wait_for_dump_helpers(cprm.file);
O
Oleg Nesterov 已提交
2000 2001 2002
close_fail:
	if (cprm.file)
		filp_close(cprm.file, NULL);
2003
fail_dropcount:
O
Oleg Nesterov 已提交
2004
	if (ispipe)
2005
		atomic_dec(&core_dump_count);
L
Linus Torvalds 已提交
2006
fail_unlock:
2007
	coredump_finish(mm);
D
David Howells 已提交
2008
	revert_creds(old_cred);
2009
fail_creds:
D
David Howells 已提交
2010
	put_cred(cred);
L
Linus Torvalds 已提交
2011
fail:
W
WANG Cong 已提交
2012
	return;
L
Linus Torvalds 已提交
2013
}