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From: NeilBrown <neilb@suse.de>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 04/13] security/selinux: check for LOOKUP_RCU in _follow_link.
Date: Mon, 16 Mar 2015 15:43:19 +1100	[thread overview]
Message-ID: <20150316044319.23648.82820.stgit@notabene.brown> (raw)
In-Reply-To: <20150316043602.23648.52734.stgit@notabene.brown>

Some of dentry_has_perm() is not rcu-safe, so if LOOKUP_RCU
is set in selinux_inode_follow_link(), give up with
-ECHILD.

It is possible that dentry_has_perm could sometimes complete
in RCU more, in which case the flag could be propagated further
down the stack...

Signed-off-by: NeilBrown <neilb@suse.de>
---
 security/selinux/hooks.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e3074e01f058..5d4de8cbfaa6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2866,6 +2866,8 @@ static int selinux_inode_follow_link(struct dentry *dentry, int flags)
 {
 	const struct cred *cred = current_cred();
 
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
 	return dentry_has_perm(cred, dentry, FILE__READ);
 }
 



  parent reply	other threads:[~2015-03-16  4:47 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-16  4:43 [PATCH 00/13] Support follow_link in RCU-walk. - V2 NeilBrown
2015-03-16  4:43 ` [PATCH 01/13] VFS: replace {, total_}link_count in task_struct with pointer to nameidata NeilBrown
2015-03-16 19:46   ` Al Viro
2015-03-16  4:43 ` [PATCH 02/13] VFS: make all ->follow_link handlers aware for LOOKUP_RCU NeilBrown
2015-03-16  4:43 ` NeilBrown [this message]
2015-03-16 21:00   ` [PATCH 04/13] security/selinux: check for LOOKUP_RCU in _follow_link Al Viro
2015-03-20  4:39     ` NeilBrown
2015-03-20  5:12       ` Al Viro
2015-03-16  4:43 ` [PATCH 03/13] VFS: remove nameidata args from ->follow_link and ->put_link NeilBrown
2015-03-16 20:47   ` Al Viro
2015-03-16  4:43 ` [PATCH 05/13] VFS/namei: use terminate_walk when symlink lookup fails NeilBrown
2015-03-16  4:43 ` [PATCH 12/13] XFS: allow follow_link to often succeed in RCU-walk NeilBrown
2015-03-16 22:37   ` Al Viro
2015-03-16  4:43 ` [PATCH 10/13] VFS/namei: handle LOOKUP_RCU in page_follow_link_light NeilBrown
2015-03-16 22:50   ` Al Viro
2015-03-19 22:38     ` NeilBrown
2015-03-19 23:46       ` Al Viro
2015-03-16  4:43 ` [PATCH 11/13] xfs: use RCU to free 'struct xfs_mount' NeilBrown
2015-03-16  4:43 ` [PATCH 13/13] NFS: support LOOKUP_RCU in nfs_follow_link NeilBrown
2015-03-16  4:43 ` [PATCH 06/13] VFS/namei: new flag to support RCU symlinks: LOOKUP_LINK_RCU NeilBrown
2015-03-16 22:33   ` Al Viro
2015-03-17  0:59     ` Al Viro
2015-03-16  4:43 ` [PATCH 07/13] VFS/namei: abort RCU-walk on symlink if atime needs updating NeilBrown
2015-03-16  4:43 ` [PATCH 08/13] VFS/namei: enhance follow_link to support RCU-walk NeilBrown
2015-03-16  4:43 ` [PATCH 09/13] VFS/namei: enable RCU-walk when following symlinks NeilBrown
2015-03-16 22:44   ` Al Viro
2015-03-16 19:14 ` [PATCH 00/13] Support follow_link in RCU-walk. - V2 Al Viro

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