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fs,userns: Change inode_capable to capable_wrt_inode_uidgid

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The kernel has no concept of capabilities with respect to inodes; inodes
exist independently of namespaces.  For example, inode_capable(inode,
CAP_LINUX_IMMUTABLE) would be nonsense.

This patch changes inode_capable to check for uid and gid mappings and
renames it to capable_wrt_inode_uidgid, which should make it more
obvious what it does.

Fixes CVE-2014-4014.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Lutomirski 2014-06-10 12:45:42 -07:00 • committed by Linus Torvalds
parent 5b174fd647
commit 23adbe12ef
6 changed files with 27 additions and 26 deletions
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20
kernel/capability.c
View file

@ -424,23 +424,19 @@ bool capable(int cap)
EXPORT_SYMBOL(capable);
/**
* inode_capable - Check superior capability over inode
* capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
* @inode: The inode in question
* @cap: The capability in question
*
* Return true if the current task has the given superior capability
* targeted at it's own user namespace and that the given inode is owned
* by the current user namespace or a child namespace.
*
* Currently we check to see if an inode is owned by the current
* user namespace by seeing if the inode's owner maps into the
* current user namespace.
*
* Return true if the current task has the given capability targeted at
* its own user namespace and that the given inode's uid and gid are
* mapped into the current user namespace.
*/
bool inode_capable(const struct inode *inode, int cap)
bool capable_wrt_inode_uidgid(const struct inode *inode, int cap)
{
struct user_namespace *ns = current_user_ns();
return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid);
return ns_capable(ns, cap) && kuid_has_mapping(ns, inode->i_uid) &&
kgid_has_mapping(ns, inode->i_gid);
}
EXPORT_SYMBOL(inode_capable);
EXPORT_SYMBOL(capable_wrt_inode_uidgid);