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linux-next/fs/internal.h
Hugh Dickins e426b64c41 fix setuid sometimes doesn't
Joe Malicki reports that setuid sometimes doesn't: very rarely,
a setuid root program does not get root euid; and, by the way,
they have a health check running lsof every few minutes.

Right, check_unsafe_exec() notes whether the files_struct is being
shared by more threads than will get killed by the exec, and if so
sets LSM_UNSAFE_SHARE to make bprm_set_creds() careful about euid.
But /proc/<pid>/fd and /proc/<pid>/fdinfo lookups make transient
use of get_files_struct(), which also raises that sharing count.

There's a rather simple fix for this: exec's check on files->count
has been redundant ever since 2.6.1 made it unshare_files() (except
while compat_do_execve() omitted to do so) - just remove that check.

[Note to -stable: this patch will not apply before 2.6.29: earlier
releases should just remove the files->count line from unsafe_exec().]

Reported-by: Joe Malicki <jmalicki@metacarta.com>
Narrowed-down-by: Michael Itz <mitz@metacarta.com>
Tested-by: Joe Malicki <jmalicki@metacarta.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-28 17:30:00 -07:00

63 lines
1.5 KiB
C

/* fs/ internal definitions
*
* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
struct super_block;
struct linux_binprm;
/*
* block_dev.c
*/
#ifdef CONFIG_BLOCK
extern struct super_block *blockdev_superblock;
extern void __init bdev_cache_init(void);
static inline int sb_is_blkdev_sb(struct super_block *sb)
{
return sb == blockdev_superblock;
}
#else
static inline void bdev_cache_init(void)
{
}
static inline int sb_is_blkdev_sb(struct super_block *sb)
{
return 0;
}
#endif
/*
* char_dev.c
*/
extern void __init chrdev_init(void);
/*
* exec.c
*/
extern void check_unsafe_exec(struct linux_binprm *);
/*
* namespace.c
*/
extern int copy_mount_options(const void __user *, unsigned long *);
extern void free_vfsmnt(struct vfsmount *);
extern struct vfsmount *alloc_vfsmnt(const char *);
extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
struct vfsmount *);
extern void release_mounts(struct list_head *);
extern void umount_tree(struct vfsmount *, int, struct list_head *);
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
extern void __init mnt_init(void);