exec.c 40.6 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>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
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#include <linux/string.h>
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#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/key.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/swap.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/ptrace.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/rmap.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 <asm/uaccess.h>
#include <asm/mmu_context.h>
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#include <asm/tlb.h>
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#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif

int core_uses_pid;
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char core_pattern[CORENAME_MAX_SIZE] = "core";
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int suid_dumpable = 0;

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

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

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

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.
 */
asmlinkage long sys_uselib(const char __user * library)
{
	struct file * file;
	struct nameidata nd;
	int error;

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	error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
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	if (error)
		goto out;

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

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	error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
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	if (error)
		goto exit;

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	file = nameidata_to_filp(&nd, O_RDONLY);
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	error = PTR_ERR(file);
	if (IS_ERR(file))
		goto out;

	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);
	}
	fput(file);
out:
  	return error;
exit:
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	release_open_intent(&nd);
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	path_release(&nd);
	goto out;
}

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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) {
		struct rlimit *rlim = current->signal->rlim;
		unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;

		/*
		 * 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.
		 */
		if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
			put_page(page);
			return NULL;
		}
	}

	return page;
}

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

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

static void free_arg_pages(struct linux_binprm *bprm)
{
}

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

static int __bprm_mm_init(struct linux_binprm *bprm)
{
	int err = -ENOMEM;
	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)
		goto err;

	down_write(&mm->mmap_sem);
	vma->vm_mm = mm;

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

	vma->vm_flags = VM_STACK_FLAGS;
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	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
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	err = insert_vm_struct(mm, vma);
	if (err) {
		up_write(&mm->mmap_sem);
		goto err;
	}

	mm->stack_vm = mm->total_vm = 1;
	up_write(&mm->mmap_sem);

	bprm->p = vma->vm_end - sizeof(void *);

	return 0;

err:
	if (vma) {
		bprm->vma = NULL;
		kmem_cache_free(vm_area_cachep, vma);
	}

	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++;
			if(++i > max)
				return -E2BIG;
			cond_resched();
		}
	}
	return i;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
	if (new_end > old_start) {
		/*
		 * when the old and new regions overlap clear from new_end.
		 */
		free_pgd_range(&tlb, new_end, old_end, new_end,
			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.
		 */
		free_pgd_range(&tlb, old_start, old_end, new_end,
			vma->vm_next ? vma->vm_next->vm_start : 0);
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	}
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	tlb_finish_mmu(tlb, new_end, old_end);

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

	return 0;
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}

#define EXTRA_STACK_VM_PAGES	20	/* random */

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

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

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

	if (bprm->loader)
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		bprm->loader -= stack_shift;
	bprm->exec -= stack_shift;
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	down_write(&mm->mmap_sem);
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	vm_flags = vma->vm_flags;

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

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

	/* Move stack pages down in memory. */
	if (stack_shift) {
		ret = shift_arg_pages(vma, stack_shift);
		if (ret) {
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			up_write(&mm->mmap_sem);
			return ret;
		}
	}

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#ifdef CONFIG_STACK_GROWSUP
	stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#else
	stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
#endif
	ret = expand_stack(vma, stack_base);
	if (ret)
		ret = -EFAULT;

out_unlock:
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	up_write(&mm->mmap_sem);
	return 0;
}
EXPORT_SYMBOL(setup_arg_pages);

#endif /* CONFIG_MMU */

struct file *open_exec(const char *name)
{
	struct nameidata nd;
	int err;
	struct file *file;

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	err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
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	file = ERR_PTR(err);

	if (!err) {
		struct inode *inode = nd.dentry->d_inode;
		file = ERR_PTR(-EACCES);
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		if (S_ISREG(inode->i_mode)) {
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			int err = vfs_permission(&nd, MAY_EXEC);
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			file = ERR_PTR(err);
			if (!err) {
661
				file = nameidata_to_filp(&nd, O_RDONLY);
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				if (!IS_ERR(file)) {
					err = deny_write_access(file);
					if (err) {
						fput(file);
						file = ERR_PTR(err);
					}
				}
out:
				return file;
			}
		}
673
		release_open_intent(&nd);
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		path_release(&nd);
	}
	goto out;
}

EXPORT_SYMBOL(open_exec);

int kernel_read(struct file *file, unsigned long offset,
	char *addr, unsigned long count)
{
	mm_segment_t old_fs;
	loff_t pos = offset;
	int result;

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

EXPORT_SYMBOL(kernel_read);

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

	/* Notify parent that we're no longer interested in the old VM */
	tsk = current;
	old_mm = current->mm;
	mm_release(tsk, old_mm);

	if (old_mm) {
		/*
		 * Make sure that if there is a core dump in progress
		 * for the old mm, we get out and die instead of going
		 * through with the exec.  We must hold mmap_sem around
		 * checking core_waiters and changing tsk->mm.  The
		 * core-inducing thread will increment core_waiters for
		 * each thread whose ->mm == old_mm.
		 */
		down_read(&old_mm->mmap_sem);
		if (unlikely(old_mm->core_waiters)) {
			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);
732
		BUG_ON(active_mm != old_mm);
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		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().)
 */
746
static int de_thread(struct task_struct *tsk)
L
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{
	struct signal_struct *sig = tsk->signal;
749
	struct sighand_struct *oldsighand = tsk->sighand;
L
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	spinlock_t *lock = &oldsighand->siglock;
751
	struct task_struct *leader = NULL;
L
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	int count;

754
	if (thread_group_empty(tsk))
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		goto no_thread_group;

	/*
	 * Kill all other threads in the thread group.
	 * We must hold tasklist_lock to call zap_other_threads.
	 */
	read_lock(&tasklist_lock);
	spin_lock_irq(lock);
763
	if (signal_group_exit(sig)) {
L
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		/*
		 * Another group action in progress, just
		 * return so that the signal is processed.
		 */
		spin_unlock_irq(lock);
		read_unlock(&tasklist_lock);
		return -EAGAIN;
	}
772 773 774 775 776 777

	/*
	 * child_reaper ignores SIGKILL, change it now.
	 * Reparenting needs write_lock on tasklist_lock,
	 * so it is safe to do it under read_lock.
	 */
778
	if (unlikely(tsk->group_leader == task_child_reaper(tsk)))
779
		task_active_pid_ns(tsk)->child_reaper = tsk;
780

781
	sig->group_exit_task = tsk;
782
	zap_other_threads(tsk);
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	read_unlock(&tasklist_lock);

785 786
	/* Account for the thread group leader hanging around: */
	count = thread_group_leader(tsk) ? 1 : 2;
787
	sig->notify_count = count;
L
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	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:
	 */
801 802
	if (!thread_group_leader(tsk)) {
		leader = tsk->group_leader;
803 804 805 806 807 808 809 810 811 812

		sig->notify_count = -1;
		for (;;) {
			write_lock_irq(&tasklist_lock);
			if (likely(leader->exit_state))
				break;
			__set_current_state(TASK_UNINTERRUPTIBLE);
			write_unlock_irq(&tasklist_lock);
			schedule();
		}
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Linus Torvalds 已提交
813

814 815 816 817 818 819 820 821 822 823
		/*
		 * 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).
		 */
824
		tsk->start_time = leader->start_time;
825

826 827
		BUG_ON(!same_thread_group(leader, tsk));
		BUG_ON(has_group_leader_pid(tsk));
L
Linus Torvalds 已提交
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		/*
		 * 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:
		 */
834 835

		/* Become a process group leader with the old leader's pid.
836 837
		 * The old leader becomes a thread of the this thread group.
		 * Note: The old leader also uses this pid until release_task
838 839
		 *       is called.  Odd but simple and correct.
		 */
840 841
		detach_pid(tsk, PIDTYPE_PID);
		tsk->pid = leader->pid;
842
		attach_pid(tsk, PIDTYPE_PID,  task_pid(leader));
843 844 845
		transfer_pid(leader, tsk, PIDTYPE_PGID);
		transfer_pid(leader, tsk, PIDTYPE_SID);
		list_replace_rcu(&leader->tasks, &tsk->tasks);
L
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846

847 848
		tsk->group_leader = tsk;
		leader->group_leader = tsk;
849

850
		tsk->exit_signal = SIGCHLD;
851 852 853

		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
		leader->exit_state = EXIT_DEAD;
L
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854 855

		write_unlock_irq(&tasklist_lock);
856
	}
L
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857

858 859
	sig->group_exit_task = NULL;
	sig->notify_count = 0;
L
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860 861 862

no_thread_group:
	exit_itimers(sig);
863 864 865
	if (leader)
		release_task(leader);

866 867
	if (atomic_read(&oldsighand->count) != 1) {
		struct sighand_struct *newsighand;
L
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868
		/*
869 870
		 * This ->sighand is shared with the CLONE_SIGHAND
		 * but not CLONE_THREAD task, switch to the new one.
L
Linus Torvalds 已提交
871
		 */
872 873 874 875
		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
		if (!newsighand)
			return -ENOMEM;

L
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		atomic_set(&newsighand->count, 1);
		memcpy(newsighand->action, oldsighand->action,
		       sizeof(newsighand->action));

		write_lock_irq(&tasklist_lock);
		spin_lock(&oldsighand->siglock);
882
		rcu_assign_pointer(tsk->sighand, newsighand);
L
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883 884 885
		spin_unlock(&oldsighand->siglock);
		write_unlock_irq(&tasklist_lock);

886
		__cleanup_sighand(oldsighand);
L
Linus Torvalds 已提交
887 888
	}

889
	BUG_ON(!thread_group_leader(tsk));
L
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890 891
	return 0;
}
O
Oleg Nesterov 已提交
892

L
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893 894 895 896
/*
 * These functions flushes out all traces of the currently running executable
 * so that a new one can be started
 */
897
static void flush_old_files(struct files_struct * files)
L
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898 899
{
	long j = -1;
900
	struct fdtable *fdt;
L
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901 902 903 904 905 906 907

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

		j++;
		i = j * __NFDBITS;
908
		fdt = files_fdtable(files);
909
		if (i >= fdt->max_fds)
L
Linus Torvalds 已提交
910
			break;
911
		set = fdt->close_on_exec->fds_bits[j];
L
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912 913
		if (!set)
			continue;
914
		fdt->close_on_exec->fds_bits[j] = 0;
L
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		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);
}

927
char *get_task_comm(char *buf, struct task_struct *tsk)
L
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928 929 930 931 932
{
	/* buf must be at least sizeof(tsk->comm) in size */
	task_lock(tsk);
	strncpy(buf, tsk->comm, sizeof(tsk->comm));
	task_unlock(tsk);
933
	return buf;
L
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}

void set_task_comm(struct task_struct *tsk, char *buf)
{
	task_lock(tsk);
	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
	task_unlock(tsk);
}

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

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

	/*
	 * Make sure we have private file handles. Ask the
	 * fork helper to do the work for us and the exit
	 * helper to do the cleanup of the old one.
	 */
	files = current->files;		/* refcounted so safe to hold */
	retval = unshare_files();
	if (retval)
		goto out;
	/*
	 * Release all of the old mmap stuff
	 */
	retval = exec_mmap(bprm->mm);
	if (retval)
		goto mmap_failed;

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

	/* This is the point of no return */
	put_files_struct(files);

	current->sas_ss_sp = current->sas_ss_size = 0;

	if (current->euid == current->uid && current->egid == current->gid)
982
		set_dumpable(current->mm, 1);
A
Alan Cox 已提交
983
	else
984
		set_dumpable(current->mm, suid_dumpable);
A
Alan Cox 已提交
985

L
Linus Torvalds 已提交
986
	name = bprm->filename;
987 988

	/* Copies the binary name from after last slash */
L
Linus Torvalds 已提交
989 990
	for (i=0; (ch = *(name++)) != '\0';) {
		if (ch == '/')
991
			i = 0; /* overwrite what we wrote */
L
Linus Torvalds 已提交
992 993 994 995 996 997 998 999 1000 1001
		else
			if (i < (sizeof(tcomm) - 1))
				tcomm[i++] = ch;
	}
	tcomm[i] = '\0';
	set_task_comm(current, tcomm);

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

1002 1003 1004 1005 1006 1007
	/* 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;

1008 1009 1010 1011 1012 1013
	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
		suid_keys(current);
		set_dumpable(current->mm, suid_dumpable);
		current->pdeath_signal = 0;
	} else if (file_permission(bprm->file, MAY_READ) ||
			(bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
L
Linus Torvalds 已提交
1014
		suid_keys(current);
1015
		set_dumpable(current->mm, suid_dumpable);
L
Linus Torvalds 已提交
1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
	}

	/* An exec changes our domain. We are no longer part of the thread
	   group */

	current->self_exec_id++;
			
	flush_signal_handlers(current, 0);
	flush_old_files(current->files);

	return 0;

mmap_failed:
1029
	reset_files_struct(current, files);
L
Linus Torvalds 已提交
1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042
out:
	return retval;
}

EXPORT_SYMBOL(flush_old_exec);

/* 
 * Fill the binprm structure from the inode. 
 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
 */
int prepare_binprm(struct linux_binprm *bprm)
{
	int mode;
1043
	struct inode * inode = bprm->file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1044 1045 1046 1047 1048 1049 1050 1051 1052
	int retval;

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

	bprm->e_uid = current->euid;
	bprm->e_gid = current->egid;

1053
	if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
L
Linus Torvalds 已提交
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
		/* Set-uid? */
		if (mode & S_ISUID) {
			current->personality &= ~PER_CLEAR_ON_SETID;
			bprm->e_uid = inode->i_uid;
		}

		/* 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)) {
			current->personality &= ~PER_CLEAR_ON_SETID;
			bprm->e_gid = inode->i_gid;
		}
	}

	/* fill in binprm security blob */
	retval = security_bprm_set(bprm);
	if (retval)
		return retval;

	memset(bprm->buf,0,BINPRM_BUF_SIZE);
	return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
}

EXPORT_SYMBOL(prepare_binprm);

1083
static int unsafe_exec(struct task_struct *p)
L
Linus Torvalds 已提交
1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
{
	int unsafe = 0;
	if (p->ptrace & PT_PTRACED) {
		if (p->ptrace & PT_PTRACE_CAP)
			unsafe |= LSM_UNSAFE_PTRACE_CAP;
		else
			unsafe |= LSM_UNSAFE_PTRACE;
	}
	if (atomic_read(&p->fs->count) > 1 ||
	    atomic_read(&p->files->count) > 1 ||
	    atomic_read(&p->sighand->count) > 1)
		unsafe |= LSM_UNSAFE_SHARE;

	return unsafe;
}

void compute_creds(struct linux_binprm *bprm)
{
	int unsafe;

1104
	if (bprm->e_uid != current->uid) {
L
Linus Torvalds 已提交
1105
		suid_keys(current);
1106 1107
		current->pdeath_signal = 0;
	}
L
Linus Torvalds 已提交
1108 1109 1110 1111 1112 1113 1114 1115 1116 1117
	exec_keys(current);

	task_lock(current);
	unsafe = unsafe_exec(current);
	security_bprm_apply_creds(bprm, unsafe);
	task_unlock(current);
	security_bprm_post_apply_creds(bprm);
}
EXPORT_SYMBOL(compute_creds);

N
Nick Piggin 已提交
1118 1119 1120 1121 1122
/*
 * 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.
 */
1123
int remove_arg_zero(struct linux_binprm *bprm)
L
Linus Torvalds 已提交
1124
{
1125 1126 1127 1128
	int ret = 0;
	unsigned long offset;
	char *kaddr;
	struct page *page;
N
Nick Piggin 已提交
1129

1130 1131
	if (!bprm->argc)
		return 0;
L
Linus Torvalds 已提交
1132

1133 1134 1135 1136 1137 1138 1139 1140
	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
1141

1142 1143 1144
		for (; offset < PAGE_SIZE && kaddr[offset];
				offset++, bprm->p++)
			;
N
Nick Piggin 已提交
1145

1146 1147
		kunmap_atomic(kaddr, KM_USER0);
		put_arg_page(page);
N
Nick Piggin 已提交
1148

1149 1150 1151
		if (offset == PAGE_SIZE)
			free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
	} while (offset == PAGE_SIZE);
N
Nick Piggin 已提交
1152

1153 1154 1155
	bprm->p++;
	bprm->argc--;
	ret = 0;
N
Nick Piggin 已提交
1156

1157 1158
out:
	return ret;
L
Linus Torvalds 已提交
1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
}
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)
{
	int try,retval;
	struct linux_binfmt *fmt;
#ifdef __alpha__
	/* handle /sbin/loader.. */
	{
	    struct exec * eh = (struct exec *) bprm->buf;

	    if (!bprm->loader && eh->fh.f_magic == 0x183 &&
		(eh->fh.f_flags & 0x3000) == 0x3000)
	    {
		struct file * file;
		unsigned long loader;

		allow_write_access(bprm->file);
		fput(bprm->file);
		bprm->file = NULL;

1184
		loader = bprm->vma->vm_end - sizeof(void *);
L
Linus Torvalds 已提交
1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210

		file = open_exec("/sbin/loader");
		retval = PTR_ERR(file);
		if (IS_ERR(file))
			return retval;

		/* Remember if the application is TASO.  */
		bprm->sh_bang = eh->ah.entry < 0x100000000UL;

		bprm->file = file;
		bprm->loader = loader;
		retval = prepare_binprm(bprm);
		if (retval<0)
			return retval;
		/* should call search_binary_handler recursively here,
		   but it does not matter */
	    }
	}
#endif
	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
1211 1212 1213 1214 1215

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

L
Linus Torvalds 已提交
1216 1217 1218
	retval = -ENOENT;
	for (try=0; try<2; try++) {
		read_lock(&binfmt_lock);
A
Alexey Dobriyan 已提交
1219
		list_for_each_entry(fmt, &formats, lh) {
L
Linus Torvalds 已提交
1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233
			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);
			if (retval >= 0) {
				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
1234
				proc_exec_connector(current);
L
Linus Torvalds 已提交
1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275
				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;
#ifdef CONFIG_KMOD
		}else{
#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;
P
Peter Zijlstra 已提交
1276
	unsigned long env_p;
L
Linus Torvalds 已提交
1277 1278 1279
	int retval;

	retval = -ENOMEM;
1280
	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
L
Linus Torvalds 已提交
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294
	if (!bprm)
		goto out_ret;

	file = open_exec(filename);
	retval = PTR_ERR(file);
	if (IS_ERR(file))
		goto out_kfree;

	sched_exec();

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

1295 1296 1297
	retval = bprm_mm_init(bprm);
	if (retval)
		goto out_file;
L
Linus Torvalds 已提交
1298

1299
	bprm->argc = count(argv, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1300 1301 1302
	if ((retval = bprm->argc) < 0)
		goto out_mm;

1303
	bprm->envc = count(envp, MAX_ARG_STRINGS);
L
Linus Torvalds 已提交
1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323
	if ((retval = bprm->envc) < 0)
		goto out_mm;

	retval = security_bprm_alloc(bprm);
	if (retval)
		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;

P
Peter Zijlstra 已提交
1324
	env_p = bprm->p;
L
Linus Torvalds 已提交
1325 1326 1327
	retval = copy_strings(bprm->argc, argv, bprm);
	if (retval < 0)
		goto out;
P
Peter Zijlstra 已提交
1328
	bprm->argv_len = env_p - bprm->p;
L
Linus Torvalds 已提交
1329 1330 1331 1332

	retval = search_binary_handler(bprm,regs);
	if (retval >= 0) {
		/* execve success */
1333
		free_arg_pages(bprm);
L
Linus Torvalds 已提交
1334 1335 1336 1337 1338 1339 1340
		security_bprm_free(bprm);
		acct_update_integrals(current);
		kfree(bprm);
		return retval;
	}

out:
1341
	free_arg_pages(bprm);
L
Linus Torvalds 已提交
1342 1343 1344 1345 1346
	if (bprm->security)
		security_bprm_free(bprm);

out_mm:
	if (bprm->mm)
1347
		mmput (bprm->mm);
L
Linus Torvalds 已提交
1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380

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

out_ret:
	return retval;
}

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

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

EXPORT_SYMBOL(set_binfmt);

/* format_corename will inspect the pattern parameter, and output a
 * name into corename, which must have space for at least
 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
 */
1381
static int format_corename(char *corename, const char *pattern, long signr)
L
Linus Torvalds 已提交
1382 1383 1384 1385 1386 1387
{
	const char *pat_ptr = pattern;
	char *out_ptr = corename;
	char *const out_end = corename + CORENAME_MAX_SIZE;
	int rc;
	int pid_in_pattern = 0;
1388 1389 1390 1391
	int ispipe = 0;

	if (*pattern == '|')
		ispipe = 1;
L
Linus Torvalds 已提交
1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413

	/* 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,
1414
					      "%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* uid */
			case 'u':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%d", current->uid);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
			/* gid */
			case 'g':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%d", current->gid);
				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,
1458
					      "%s", utsname()->nodename);
L
Linus Torvalds 已提交
1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471
				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;
1472 1473 1474 1475 1476 1477 1478 1479
			/* core limit size */
			case 'c':
				rc = snprintf(out_ptr, out_end - out_ptr,
					      "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
				if (rc > out_end - out_ptr)
					goto out;
				out_ptr += rc;
				break;
L
Linus Torvalds 已提交
1480 1481 1482 1483 1484 1485 1486 1487 1488 1489
			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
1490 1491
	 * the filename. Do not do this for piped commands. */
	if (!ispipe && !pid_in_pattern
L
Linus Torvalds 已提交
1492 1493
            && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
		rc = snprintf(out_ptr, out_end - out_ptr,
1494
			      ".%d", task_tgid_vnr(current));
L
Linus Torvalds 已提交
1495 1496 1497 1498
		if (rc > out_end - out_ptr)
			goto out;
		out_ptr += rc;
	}
1499
out:
L
Linus Torvalds 已提交
1500
	*out_ptr = 0;
1501
	return ispipe;
L
Linus Torvalds 已提交
1502 1503
}

1504
static void zap_process(struct task_struct *start)
1505 1506
{
	struct task_struct *t;
1507

1508 1509
	start->signal->flags = SIGNAL_GROUP_EXIT;
	start->signal->group_stop_count = 0;
1510 1511 1512 1513 1514

	t = start;
	do {
		if (t != current && t->mm) {
			t->mm->core_waiters++;
1515 1516
			sigaddset(&t->pending.signal, SIGKILL);
			signal_wake_up(t, 1);
1517 1518 1519 1520
		}
	} while ((t = next_thread(t)) != start);
}

1521 1522
static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
				int exit_code)
L
Linus Torvalds 已提交
1523 1524
{
	struct task_struct *g, *p;
1525
	unsigned long flags;
1526 1527 1528
	int err = -EAGAIN;

	spin_lock_irq(&tsk->sighand->siglock);
1529
	if (!signal_group_exit(tsk->signal)) {
1530
		tsk->signal->group_exit_code = exit_code;
1531
		zap_process(tsk);
1532
		err = 0;
L
Linus Torvalds 已提交
1533
	}
1534 1535 1536
	spin_unlock_irq(&tsk->sighand->siglock);
	if (err)
		return err;
L
Linus Torvalds 已提交
1537

1538 1539 1540
	if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
		goto done;

1541
	rcu_read_lock();
1542
	for_each_process(g) {
1543 1544 1545
		if (g == tsk->group_leader)
			continue;

1546 1547 1548
		p = g;
		do {
			if (p->mm) {
1549 1550 1551 1552 1553 1554
				if (p->mm == mm) {
					/*
					 * p->sighand can't disappear, but
					 * may be changed by de_thread()
					 */
					lock_task_sighand(p, &flags);
1555
					zap_process(p);
1556 1557
					unlock_task_sighand(p, &flags);
				}
1558 1559 1560 1561
				break;
			}
		} while ((p = next_thread(p)) != g);
	}
1562
	rcu_read_unlock();
1563
done:
1564
	return mm->core_waiters;
L
Linus Torvalds 已提交
1565 1566
}

1567
static int coredump_wait(int exit_code)
L
Linus Torvalds 已提交
1568
{
1569 1570 1571 1572
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	struct completion startup_done;
	struct completion *vfork_done;
O
Oleg Nesterov 已提交
1573
	int core_waiters;
L
Linus Torvalds 已提交
1574

1575 1576
	init_completion(&mm->core_done);
	init_completion(&startup_done);
L
Linus Torvalds 已提交
1577 1578
	mm->core_startup_done = &startup_done;

1579
	core_waiters = zap_threads(tsk, mm, exit_code);
O
Oleg Nesterov 已提交
1580 1581
	up_write(&mm->mmap_sem);

1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594
	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
1595
	if (core_waiters)
L
Linus Torvalds 已提交
1596
		wait_for_completion(&startup_done);
1597
fail:
L
Linus Torvalds 已提交
1598
	BUG_ON(mm->core_waiters);
1599
	return core_waiters;
L
Linus Torvalds 已提交
1600 1601
}

1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650
/*
 * set_dumpable converts traditional three-value dumpable to two flags and
 * stores them into mm->flags.  It modifies lower two bits of mm->flags, but
 * these bits are not changed atomically.  So get_dumpable can observe the
 * intermediate state.  To avoid doing unexpected behavior, get get_dumpable
 * return either old dumpable or new one by paying attention to the order of
 * modifying the bits.
 *
 * dumpable |   mm->flags (binary)
 * old  new | initial interim  final
 * ---------+-----------------------
 *  0    1  |   00      01      01
 *  0    2  |   00      10(*)   11
 *  1    0  |   01      00      00
 *  1    2  |   01      11      11
 *  2    0  |   11      10(*)   00
 *  2    1  |   11      11      01
 *
 * (*) get_dumpable regards interim value of 10 as 11.
 */
void set_dumpable(struct mm_struct *mm, int value)
{
	switch (value) {
	case 0:
		clear_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 1:
		set_bit(MMF_DUMPABLE, &mm->flags);
		smp_wmb();
		clear_bit(MMF_DUMP_SECURELY, &mm->flags);
		break;
	case 2:
		set_bit(MMF_DUMP_SECURELY, &mm->flags);
		smp_wmb();
		set_bit(MMF_DUMPABLE, &mm->flags);
		break;
	}
}

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

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

L
Linus Torvalds 已提交
1651 1652 1653 1654 1655 1656 1657 1658
int do_coredump(long signr, int exit_code, struct pt_regs * regs)
{
	char corename[CORENAME_MAX_SIZE + 1];
	struct mm_struct *mm = current->mm;
	struct linux_binfmt * binfmt;
	struct inode * inode;
	struct file * file;
	int retval = 0;
A
Alan Cox 已提交
1659 1660
	int fsuid = current->fsuid;
	int flag = 0;
1661
	int ispipe = 0;
1662
	unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1663 1664 1665
	char **helper_argv = NULL;
	int helper_argc = 0;
	char *delimit;
L
Linus Torvalds 已提交
1666

S
Steve Grubb 已提交
1667 1668
	audit_core_dumps(signr);

L
Linus Torvalds 已提交
1669 1670 1671 1672
	binfmt = current->binfmt;
	if (!binfmt || !binfmt->core_dump)
		goto fail;
	down_write(&mm->mmap_sem);
R
Roland McGrath 已提交
1673 1674 1675 1676
	/*
	 * If another thread got here first, or we are not dumpable, bail out.
	 */
	if (mm->core_waiters || !get_dumpable(mm)) {
L
Linus Torvalds 已提交
1677 1678 1679
		up_write(&mm->mmap_sem);
		goto fail;
	}
A
Alan Cox 已提交
1680 1681 1682 1683 1684 1685

	/*
	 *	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.
	 */
1686
	if (get_dumpable(mm) == 2) {	/* Setuid core dump mode */
A
Alan Cox 已提交
1687 1688 1689
		flag = O_EXCL;		/* Stop rewrite attacks */
		current->fsuid = 0;	/* Dump root private */
	}
1690

1691 1692
	retval = coredump_wait(exit_code);
	if (retval < 0)
1693
		goto fail;
L
Linus Torvalds 已提交
1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705

	/*
	 * 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();
1706
	ispipe = format_corename(corename, core_pattern, signr);
L
Linus Torvalds 已提交
1707
	unlock_kernel();
1708 1709 1710 1711 1712 1713 1714 1715
	/*
	 * Don't bother to check the RLIMIT_CORE value if core_pattern points
	 * to a pipe.  Since we're not writing directly to the filesystem
	 * RLIMIT_CORE doesn't really apply, as no actual core file will be
	 * created unless the pipe reader choses to write out the core file
	 * at which point file size limits and permissions will be imposed
	 * as it does with any other process
	 */
1716
	if ((!ispipe) && (core_limit < binfmt->min_coredump))
1717 1718
		goto fail_unlock;

1719
 	if (ispipe) {
1720 1721 1722 1723 1724
		helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
		/* Terminate the string before the first option */
		delimit = strchr(corename, ' ');
		if (delimit)
			*delimit = '\0';
1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737
		delimit = strrchr(helper_argv[0], '/');
		if (delimit)
			delimit++;
		else
			delimit = helper_argv[0];
		if (!strcmp(delimit, current->comm)) {
			printk(KERN_NOTICE "Recursive core dump detected, "
					"aborting\n");
			goto fail_unlock;
		}

		core_limit = RLIM_INFINITY;

1738
		/* SIGPIPE can happen, but it's just never processed */
1739 1740
 		if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
				&file)) {
1741 1742 1743 1744 1745 1746
 			printk(KERN_INFO "Core dump to %s pipe failed\n",
			       corename);
 			goto fail_unlock;
 		}
 	} else
 		file = filp_open(corename,
1747 1748
				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
				 0600);
L
Linus Torvalds 已提交
1749 1750
	if (IS_ERR(file))
		goto fail_unlock;
1751
	inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1752 1753
	if (inode->i_nlink > 1)
		goto close_fail;	/* multiple links - don't dump */
1754
	if (!ispipe && d_unhashed(file->f_path.dentry))
L
Linus Torvalds 已提交
1755 1756
		goto close_fail;

1757 1758 1759
	/* AK: actually i see no reason to not allow this for named pipes etc.,
	   but keep the previous behaviour for now. */
	if (!ispipe && !S_ISREG(inode->i_mode))
L
Linus Torvalds 已提交
1760
		goto close_fail;
I
Ingo Molnar 已提交
1761 1762 1763 1764 1765 1766
	/*
	 * 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;
L
Linus Torvalds 已提交
1767 1768 1769 1770
	if (!file->f_op)
		goto close_fail;
	if (!file->f_op->write)
		goto close_fail;
1771
	if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
L
Linus Torvalds 已提交
1772 1773
		goto close_fail;

1774
	retval = binfmt->core_dump(signr, regs, file, core_limit);
L
Linus Torvalds 已提交
1775 1776 1777 1778 1779 1780

	if (retval)
		current->signal->group_exit_code |= 0x80;
close_fail:
	filp_close(file, NULL);
fail_unlock:
1781 1782 1783
	if (helper_argv)
		argv_free(helper_argv);

A
Alan Cox 已提交
1784
	current->fsuid = fsuid;
L
Linus Torvalds 已提交
1785 1786 1787 1788
	complete_all(&mm->core_done);
fail:
	return retval;
}