exec.c 46.2 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/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);
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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;
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	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);
630 631
		if (ret)
			goto out_unlock;
L
Linus Torvalds 已提交
632 633
	}

634 635 636
	/* mprotect_fixup is overkill to remove the temporary stack flags */
	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;

637
	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
638 639 640 641 642 643
	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;
644
#ifdef CONFIG_STACK_GROWSUP
645 646 647 648
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_start + rlim_stack;
	else
		stack_base = vma->vm_end + stack_expand;
649
#else
650 651 652 653
	if (stack_size + stack_expand > rlim_stack)
		stack_base = vma->vm_end - rlim_stack;
	else
		stack_base = vma->vm_start - stack_expand;
654
#endif
655
	current->mm->start_stack = bprm->p;
656 657 658 659 660
	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
	fsnotify_open(file);
687

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
	spinlock_t *lock = &oldsighand->siglock;

772
	if (thread_group_empty(tsk))
L
Linus Torvalds 已提交
773 774 775 776 777 778
		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 */
	spin_lock_irq(lock);
779
	if (signal_group_exit(sig)) {
L
Linus Torvalds 已提交
780 781 782 783 784 785 786
		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		return -EAGAIN;
	}
787

788
	sig->group_exit_task = tsk;
789 790 791
	sig->notify_count = zap_other_threads(tsk);
	if (!thread_group_leader(tsk))
		sig->notify_count--;
L
Linus Torvalds 已提交
792

793
	while (sig->notify_count) {
L
Linus Torvalds 已提交
794 795 796 797 798 799 800 801 802 803 804 805
		__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:
	 */
806
	if (!thread_group_leader(tsk)) {
807
		struct task_struct *leader = tsk->group_leader;
808

809
		sig->notify_count = -1;	/* for exit_notify() */
810 811 812 813 814 815 816 817
		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
818

819 820 821 822 823 824 825 826 827 828
		/*
		 * 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).
		 */
829
		tsk->start_time = leader->start_time;
830

831 832
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
833 834 835 836 837 838
		/*
		 * 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:
		 */
839 840

		/* Become a process group leader with the old leader's pid.
841 842
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
843 844
		 *       is called.  Odd but simple and correct.
		 */
845 846
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
847
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
848 849
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
850

851
		list_replace_rcu(&leader->tasks, &tsk->tasks);
852
		list_replace_init(&leader->sibling, &tsk->sibling);
L
Linus Torvalds 已提交
853

854 855
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
856

857
		tsk->exit_signal = SIGCHLD;
858 859 860

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
Linus Torvalds 已提交
861
		write_unlock_irq(&tasklist_lock);
862 863

		release_task(leader);
864
	}
L
Linus Torvalds 已提交
865

866 867
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
Linus Torvalds 已提交
868 869

no_thread_group:
J
Jiri Pirko 已提交
870 871 872
	if (current->mm)
		setmax_mm_hiwater_rss(&sig->maxrss, current->mm);

L
Linus Torvalds 已提交
873
	exit_itimers(sig);
874
	flush_itimer_signals();
875

876 877
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
Linus Torvalds 已提交
878
		/*
879 880
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
881
		 */
882 883 884 885
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
Linus Torvalds 已提交
886 887 888 889 890 891
		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
892
		rcu_assign_pointer(tsk->sighand, newsighand);
L
Linus Torvalds 已提交
893 894 895
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

896
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
897 898
	}

899
	BUG_ON(!thread_group_leader(tsk));
L
Linus Torvalds 已提交
900 901
	return 0;
}
O
Oleg Nesterov 已提交
902

L
Linus Torvalds 已提交
903 904 905 906
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
907
static void flush_old_files(struct files_struct * files)
L
Linus Torvalds 已提交
908 909
{
	long j = -1;
910
	struct fdtable *fdt;
L
Linus Torvalds 已提交
911 912 913 914 915 916 917

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

		j++;
		i = j * __NFDBITS;
918
		fdt = files_fdtable(files);
919
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
920
			break;
921
		set = fdt->close_on_exec->fds_bits[j];
L
Linus Torvalds 已提交
922 923
		if (!set)
			continue;
924
		fdt->close_on_exec->fds_bits[j] = 0;
L
Linus Torvalds 已提交
925 926 927 928 929 930 931 932 933 934 935 936
		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);
}

937
char *get_task_comm(char *buf, struct task_struct *tsk)
L
Linus Torvalds 已提交
938 939 940 941 942
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
943
	return buf;
L
Linus Torvalds 已提交
944 945 946 947 948
}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
949 950 951 952 953 954 955 956 957

	/*
	 * 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
958 959
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
960
	perf_event_comm(tsk);
L
Linus Torvalds 已提交
961 962 963 964
}

int flush_old_exec(struct linux_binprm * bprm)
{
965
	int retval;
L
Linus Torvalds 已提交
966 967 968 969 970 971 972 973 974

	/*
	 * 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
975 976
	set_mm_exe_file(bprm->mm, bprm->file);

L
Linus Torvalds 已提交
977 978 979 980 981
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
982
		goto out;
L
Linus Torvalds 已提交
983 984

	bprm->mm = NULL;		/* We're using it now */
985 986 987 988 989

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

990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003
	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
1004 1005 1006 1007

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

1008
	if (current_euid() == current_uid() && current_egid() == current_gid())
1009
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
1010
	else
1011
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
1012

L
Linus Torvalds 已提交
1013
	name = bprm->filename;
1014 1015

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
1016 1017
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
1018
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
1019 1020 1021 1022 1023 1024 1025
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

1026 1027 1028 1029 1030 1031
	/* 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;

1032 1033 1034
	/* install the new credentials */
	if (bprm->cred->uid != current_euid() ||
	    bprm->cred->gid != current_egid()) {
1035 1036
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
1037
		   bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1038
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1039 1040
	}

I
Ingo Molnar 已提交
1041 1042 1043 1044 1045
	/*
	 * Flush performance counters when crossing a
	 * security domain:
	 */
	if (!get_dumpable(current->mm))
1046
		perf_event_exit_task(current);
I
Ingo Molnar 已提交
1047

L
Linus Torvalds 已提交
1048 1049 1050 1051 1052 1053 1054 1055
	/* 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);
}
1056
EXPORT_SYMBOL(setup_new_exec);
L
Linus Torvalds 已提交
1057

1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086
/*
 * 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);
}

1087 1088 1089 1090 1091 1092 1093 1094 1095
/*
 * 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;
1096 1097
	/*
	 * cred_guard_mutex must be held at least to this point to prevent
1098
	 * ptrace_attach() from altering our determination of the task's
1099 1100
	 * credentials; any time after this it may be unlocked.
	 */
1101
	security_bprm_committed_creds(bprm);
1102
	mutex_unlock(&current->cred_guard_mutex);
1103 1104 1105 1106 1107
}
EXPORT_SYMBOL(install_exec_creds);

/*
 * determine how safe it is to execute the proposed program
1108
 * - the caller must hold current->cred_guard_mutex to protect against
1109 1110
 *   PTRACE_ATTACH
 */
A
Al Viro 已提交
1111
int check_unsafe_exec(struct linux_binprm *bprm)
1112
{
D
David Howells 已提交
1113
	struct task_struct *p = current, *t;
1114
	unsigned n_fs;
A
Al Viro 已提交
1115
	int res = 0;
1116 1117 1118

	bprm->unsafe = tracehook_unsafe_exec(p);

D
David Howells 已提交
1119
	n_fs = 1;
A
Al Viro 已提交
1120
	write_lock(&p->fs->lock);
1121
	rcu_read_lock();
D
David Howells 已提交
1122 1123 1124 1125
	for (t = next_thread(p); t != p; t = next_thread(t)) {
		if (t->fs == p->fs)
			n_fs++;
	}
1126
	rcu_read_unlock();
D
David Howells 已提交
1127

1128
	if (p->fs->users > n_fs) {
1129
		bprm->unsafe |= LSM_UNSAFE_SHARE;
A
Al Viro 已提交
1130
	} else {
1131 1132 1133 1134 1135
		res = -EAGAIN;
		if (!p->fs->in_exec) {
			p->fs->in_exec = 1;
			res = 1;
		}
A
Al Viro 已提交
1136 1137 1138 1139
	}
	write_unlock(&p->fs->lock);

	return res;
1140 1141
}

L
Linus Torvalds 已提交
1142 1143 1144
/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1145 1146
 *
 * This may be called multiple times for binary chains (scripts for example).
L
Linus Torvalds 已提交
1147 1148 1149
 */
int prepare_binprm(struct linux_binprm *bprm)
{
1150
	umode_t mode;
1151
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1152 1153 1154 1155 1156 1157
	int retval;

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

1158 1159 1160
	/* 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
1161

1162
	if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1163 1164
		/* Set-uid? */
		if (mode & S_ISUID) {
1165 1166
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->euid = inode->i_uid;
L
Linus Torvalds 已提交
1167 1168 1169 1170 1171 1172 1173 1174 1175
		}

		/* 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)) {
1176 1177
			bprm->per_clear |= PER_CLEAR_ON_SETID;
			bprm->cred->egid = inode->i_gid;
L
Linus Torvalds 已提交
1178 1179 1180 1181
		}
	}

	/* fill in binprm security blob */
1182
	retval = security_bprm_set_creds(bprm);
L
Linus Torvalds 已提交
1183 1184
	if (retval)
		return retval;
1185
	bprm->cred_prepared = 1;
L
Linus Torvalds 已提交
1186

1187 1188
	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
	return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
L
Linus Torvalds 已提交
1189 1190 1191 1192
}

EXPORT_SYMBOL(prepare_binprm);

N
Nick Piggin 已提交
1193 1194 1195 1196 1197
/*
 * 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.
 */
1198
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1199
{
1200 1201 1202 1203
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1204

1205 1206
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1207

1208 1209 1210 1211 1212 1213 1214 1215
	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
1216

1217 1218 1219
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1220

1221 1222
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1223

1224 1225 1226
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1227

1228 1229 1230
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1231

1232 1233
out:
	return ret;
L
Linus Torvalds 已提交
1234 1235 1236 1237 1238 1239 1240 1241
}
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)
{
1242
	unsigned int depth = bprm->recursion_depth;
L
Linus Torvalds 已提交
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252
	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
1253 1254 1255 1256 1257

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

L
Linus Torvalds 已提交
1258 1259 1260
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1261
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1262 1263 1264 1265 1266 1267 1268
			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);
1269 1270 1271 1272 1273 1274
			/*
			 * 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
1275
			if (retval >= 0) {
1276 1277
				if (depth == 0)
					tracehook_report_exec(fmt, bprm, regs);
L
Linus Torvalds 已提交
1278 1279 1280 1281 1282 1283
				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
1284
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298
				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
1299 1300
#ifdef CONFIG_MODULES
		} else {
L
Linus Torvalds 已提交
1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325
#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;
1326
	struct files_struct *displaced;
1327
	bool clear_in_exec;
L
Linus Torvalds 已提交
1328 1329
	int retval;

1330
	retval = unshare_files(&displaced);
1331 1332 1333
	if (retval)
		goto out_ret;

L
Linus Torvalds 已提交
1334
	retval = -ENOMEM;
1335
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1336
	if (!bprm)
1337
		goto out_files;
L
Linus Torvalds 已提交
1338

1339 1340
	retval = prepare_bprm_creds(bprm);
	if (retval)
1341
		goto out_free;
A
Al Viro 已提交
1342 1343

	retval = check_unsafe_exec(bprm);
1344
	if (retval < 0)
1345
		goto out_free;
1346
	clear_in_exec = retval;
1347
	current->in_execve = 1;
1348

L
Linus Torvalds 已提交
1349 1350 1351
	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
A
Al Viro 已提交
1352
		goto out_unmark;
L
Linus Torvalds 已提交
1353 1354 1355 1356 1357 1358 1359

	sched_exec();

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

1360 1361 1362
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1363

1364
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1365
	if ((retval = bprm->argc) < 0)
1366
		goto out;
L
Linus Torvalds 已提交
1367

1368
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388
	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
1389
	current->flags &= ~PF_KTHREAD;
L
Linus Torvalds 已提交
1390
	retval = search_binary_handler(bprm,regs);
1391 1392
	if (retval < 0)
		goto out;
L
Linus Torvalds 已提交
1393

1394
	/* execve succeeded */
A
Al Viro 已提交
1395
	current->fs->in_exec = 0;
1396
	current->in_execve = 0;
1397 1398 1399 1400 1401
	acct_update_integrals(current);
	free_bprm(bprm);
	if (displaced)
		put_files_struct(displaced);
	return retval;
L
Linus Torvalds 已提交
1402

1403
out:
L
Linus Torvalds 已提交
1404
	if (bprm->mm)
1405
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1406 1407 1408 1409 1410 1411

out_file:
	if (bprm->file) {
		allow_write_access(bprm->file);
		fput(bprm->file);
	}
1412

A
Al Viro 已提交
1413
out_unmark:
1414 1415
	if (clear_in_exec)
		current->fs->in_exec = 0;
1416
	current->in_execve = 0;
1417 1418

out_free:
1419
	free_bprm(bprm);
L
Linus Torvalds 已提交
1420

1421
out_files:
1422 1423
	if (displaced)
		reset_files_struct(displaced);
L
Linus Torvalds 已提交
1424 1425 1426 1427
out_ret:
	return retval;
}

1428
void set_binfmt(struct linux_binfmt *new)
L
Linus Torvalds 已提交
1429
{
1430 1431 1432 1433
	struct mm_struct *mm = current->mm;

	if (mm->binfmt)
		module_put(mm->binfmt->module);
L
Linus Torvalds 已提交
1434

1435
	mm->binfmt = new;
1436 1437
	if (new)
		__module_get(new->module);
L
Linus Torvalds 已提交
1438 1439 1440 1441 1442 1443 1444 1445
}

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.
 */
1446
static int format_corename(char *corename, long signr)
L
Linus Torvalds 已提交
1447
{
1448
	const struct cred *cred = current_cred();
1449 1450
	const char *pat_ptr = core_pattern;
	int ispipe = (*pat_ptr == '|');
L
Linus Torvalds 已提交
1451 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
	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,
1477
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1478 1479 1480 1481 1482 1483 1484
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
1485
					      "%d", cred->uid);
L
Linus Torvalds 已提交
1486 1487 1488 1489 1490 1491 1492
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
1493
					      "%d", cred->gid);
L
Linus Torvalds 已提交
1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520
				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,
1521
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
				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;
1535 1536 1537
			/* core limit size */
			case 'c':
				rc = snprintf(out_ptr, out_end - out_ptr,
J
Jiri Slaby 已提交
1538
					      "%lu", rlimit(RLIMIT_CORE));
1539 1540 1541 1542
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
L
Linus Torvalds 已提交
1543 1544 1545 1546 1547 1548 1549 1550 1551 1552
			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
1553
	 * the filename. Do not do this for piped commands. */
1554
	if (!ispipe && !pid_in_pattern && core_uses_pid) {
L
Linus Torvalds 已提交
1555
		rc = snprintf(out_ptr, out_end - out_ptr,
1556
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1557 1558 1559 1560
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1561
out:
L
Linus Torvalds 已提交
1562
	*out_ptr = 0;
1563
	return ispipe;
L
Linus Torvalds 已提交
1564 1565
}

1566
static int zap_process(struct task_struct *start, int exit_code)
1567 1568
{
	struct task_struct *t;
1569
	int nr = 0;
1570

1571
	start->signal->flags = SIGNAL_GROUP_EXIT;
1572
	start->signal->group_exit_code = exit_code;
1573
	start->signal->group_stop_count = 0;
1574 1575 1576 1577

	t = start;
	do {
		if (t != current && t->mm) {
1578 1579
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1580
			nr++;
1581
		}
1582
	} while_each_thread(start, t);
1583 1584

	return nr;
1585 1586
}

1587
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1588
				struct core_state *core_state, int exit_code)
L
Linus Torvalds 已提交
1589 1590
{
	struct task_struct *g, *p;
1591
	unsigned long flags;
1592
	int nr = -EAGAIN;
1593 1594

	spin_lock_irq(&tsk->sighand->siglock);
1595
	if (!signal_group_exit(tsk->signal)) {
1596
		mm->core_state = core_state;
1597
		nr = zap_process(tsk, exit_code);
L
Linus Torvalds 已提交
1598
	}
1599
	spin_unlock_irq(&tsk->sighand->siglock);
1600 1601
	if (unlikely(nr < 0))
		return nr;
L
Linus Torvalds 已提交
1602

1603
	if (atomic_read(&mm->mm_users) == nr + 1)
1604
		goto done;
1605 1606
	/*
	 * We should find and kill all tasks which use this mm, and we should
1607
	 * count them correctly into ->nr_threads. We don't take tasklist
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634
	 * 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().
	 */
1635
	rcu_read_lock();
1636
	for_each_process(g) {
1637 1638
		if (g == tsk->group_leader)
			continue;
1639 1640
		if (g->flags & PF_KTHREAD)
			continue;
1641 1642 1643
		p = g;
		do {
			if (p->mm) {
1644
				if (unlikely(p->mm == mm)) {
1645
					lock_task_sighand(p, &flags);
1646
					nr += zap_process(p, exit_code);
1647 1648
					unlock_task_sighand(p, &flags);
				}
1649 1650
				break;
			}
1651
		} while_each_thread(g, p);
1652
	}
1653
	rcu_read_unlock();
1654
done:
1655
	atomic_set(&core_state->nr_threads, nr);
1656
	return nr;
L
Linus Torvalds 已提交
1657 1658
}

1659
static int coredump_wait(int exit_code, struct core_state *core_state)
L
Linus Torvalds 已提交
1660
{
1661 1662 1663
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion *vfork_done;
1664
	int core_waiters = -EBUSY;
L
Linus Torvalds 已提交
1665

1666
	init_completion(&core_state->startup);
1667 1668
	core_state->dumper.task = tsk;
	core_state->dumper.next = NULL;
1669 1670 1671 1672

	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
1673 1674
	up_write(&mm->mmap_sem);

1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687
	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
1688
	if (core_waiters)
1689
		wait_for_completion(&core_state->startup);
1690 1691
fail:
	return core_waiters;
L
Linus Torvalds 已提交
1692 1693
}

O
Oleg Nesterov 已提交
1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714
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;
}

1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755
/*
 * 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;
	}
}

1756
static int __get_dumpable(unsigned long mm_flags)
1757 1758 1759
{
	int ret;

1760
	ret = mm_flags & MMF_DUMPABLE_MASK;
1761 1762 1763
	return (ret >= 2) ? 2 : ret;
}

1764 1765 1766 1767 1768
int get_dumpable(struct mm_struct *mm)
{
	return __get_dumpable(mm->flags);
}

1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791
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);

}


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 1834 1835
/*
 * 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
1836
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
L
Linus Torvalds 已提交
1837
{
1838
	struct core_state core_state;
L
Linus Torvalds 已提交
1839 1840 1841
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
D
David Howells 已提交
1842 1843
	const struct cred *old_cred;
	struct cred *cred;
L
Linus Torvalds 已提交
1844
	int retval = 0;
A
Alan Cox 已提交
1845
	int flag = 0;
O
Oleg Nesterov 已提交
1846
	int ispipe;
1847
	static atomic_t core_dump_count = ATOMIC_INIT(0);
1848 1849 1850
	struct coredump_params cprm = {
		.signr = signr,
		.regs = regs,
J
Jiri Slaby 已提交
1851
		.limit = rlimit(RLIMIT_CORE),
1852 1853 1854 1855 1856 1857
		/*
		 * 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,
1858
	};
L
Linus Torvalds 已提交
1859

S
Steve Grubb 已提交
1860 1861
	audit_core_dumps(signr);

1862
	binfmt = mm->binfmt;
L
Linus Torvalds 已提交
1863 1864
	if (!binfmt || !binfmt->core_dump)
		goto fail;
1865 1866
	if (!__get_dumpable(cprm.mm_flags))
		goto fail;
D
David Howells 已提交
1867 1868

	cred = prepare_creds();
1869
	if (!cred)
D
David Howells 已提交
1870
		goto fail;
A
Alan Cox 已提交
1871 1872 1873 1874 1875
	/*
	 *	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.
	 */
1876 1877
	if (__get_dumpable(cprm.mm_flags) == 2) {
		/* Setuid core dump mode */
A
Alan Cox 已提交
1878
		flag = O_EXCL;		/* Stop rewrite attacks */
D
David Howells 已提交
1879
		cred->fsuid = 0;	/* Dump root private */
A
Alan Cox 已提交
1880
	}
1881

1882
	retval = coredump_wait(exit_code, &core_state);
1883 1884
	if (retval < 0)
		goto fail_creds;
D
David Howells 已提交
1885 1886

	old_cred = override_creds(cred);
L
Linus Torvalds 已提交
1887 1888 1889 1890 1891 1892 1893

	/*
	 * 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);

1894
	ispipe = format_corename(corename, signr);
1895

1896
 	if (ispipe) {
O
Oleg Nesterov 已提交
1897 1898 1899
		int dump_count;
		char **helper_argv;

1900
		if (cprm.limit == 1) {
1901 1902 1903
			/*
			 * Normally core limits are irrelevant to pipes, since
			 * we're not writing to the file system, but we use
1904 1905
			 * cprm.limit of 1 here as a speacial value. Any
			 * non-1 limit gets set to RLIM_INFINITY below, but
1906 1907
			 * a limit of 0 skips the dump.  This is a consistent
			 * way to catch recursive crashes.  We can still crash
1908
			 * if the core_pattern binary sets RLIM_CORE =  !1
1909 1910 1911 1912 1913 1914 1915
			 * 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
1916
				"Process %d(%s) has RLIMIT_CORE set to 1\n",
1917 1918 1919 1920
				task_tgid_vnr(current), current->comm);
			printk(KERN_WARNING "Aborting core\n");
			goto fail_unlock;
		}
O
Oleg Nesterov 已提交
1921
		cprm.limit = RLIM_INFINITY;
1922

1923 1924 1925 1926 1927 1928 1929 1930
		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
1931
		helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
1932 1933 1934
		if (!helper_argv) {
			printk(KERN_WARNING "%s failed to allocate memory\n",
			       __func__);
1935
			goto fail_dropcount;
1936
		}
1937

O
Oleg Nesterov 已提交
1938 1939 1940 1941 1942
		retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
					NULL, UMH_WAIT_EXEC, umh_pipe_setup,
					NULL, &cprm);
		argv_free(helper_argv);
		if (retval) {
1943 1944
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
O
Oleg Nesterov 已提交
1945
			goto close_fail;
1946
 		}
1947 1948 1949 1950 1951 1952
	} else {
		struct inode *inode;

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

1953
		cprm.file = filp_open(corename,
1954 1955
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
1956 1957
		if (IS_ERR(cprm.file))
			goto fail_unlock;
L
Linus Torvalds 已提交
1958

1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980
		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
1981

1982
	retval = binfmt->core_dump(&cprm);
L
Linus Torvalds 已提交
1983 1984
	if (retval)
		current->signal->group_exit_code |= 0x80;
O
Oleg Nesterov 已提交
1985

1986
	if (ispipe && core_pipe_limit)
1987
		wait_for_dump_helpers(cprm.file);
O
Oleg Nesterov 已提交
1988 1989 1990
close_fail:
	if (cprm.file)
		filp_close(cprm.file, NULL);
1991
fail_dropcount:
O
Oleg Nesterov 已提交
1992
	if (ispipe)
1993
		atomic_dec(&core_dump_count);
L
Linus Torvalds 已提交
1994
fail_unlock:
1995
	coredump_finish(mm);
D
David Howells 已提交
1996
	revert_creds(old_cred);
1997
fail_creds:
D
David Howells 已提交
1998
	put_cred(cred);
L
Linus Torvalds 已提交
1999
fail:
W
WANG Cong 已提交
2000
	return;
L
Linus Torvalds 已提交
2001
}