Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934035Ab1FWRqG (ORCPT ); Thu, 23 Jun 2011 13:46:06 -0400 Received: from mail.windriver.com ([147.11.1.11]:35594 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933818Ab1FWRih (ORCPT ); Thu, 23 Jun 2011 13:38:37 -0400 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Josef Bacik , Al Viro , Paul Gortmaker Subject: [34-longterm 230/247] fs: call security_d_instantiate in d_obtain_alias V2 Date: Thu, 23 Jun 2011 13:34:58 -0400 Message-Id: <1308850515-15242-171-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1308850515-15242-1-git-send-email-paul.gortmaker@windriver.com> References: <1308849690-14530-1-git-send-email-paul.gortmaker@windriver.com> <1308850515-15242-1-git-send-email-paul.gortmaker@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2437 Lines: 63 From: Josef Bacik ------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. ------------------- commit 24ff6663ccfdaf088dfa7acae489cb11ed4f43c4 upstream While trying to track down some NFS problems with BTRFS, I kept noticing I was getting -EACCESS for no apparent reason. Eric Paris and printk() helped me figure out that it was SELinux that was giving me grief, with the following denial type=AVC msg=audit(1290013638.413:95): avc: denied { 0x800000 } for pid=1772 comm="nfsd" name="" dev=sda1 ino=256 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=file Turns out this is because in d_obtain_alias if we can't find an alias we create one and do all the normal instantiation stuff, but we don't do the security_d_instantiate. Usually we are protected from getting a hashed dentry that hasn't yet run security_d_instantiate() by the parent's i_mutex, but obviously this isn't an option there, so in order to deal with the case that a second thread comes in and finds our new dentry before we get to run security_d_instantiate(), we go ahead and call it if we find a dentry already. Eric assures me that this is ok as the code checks to see if the dentry has been initialized already so calling security_d_instantiate() against the same dentry multiple times is ok. With this patch I'm no longer getting errant -EACCESS values. Signed-off-by: Josef Bacik Signed-off-by: Al Viro Signed-off-by: Paul Gortmaker --- fs/dcache.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 2b6f09a..68c70f0 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1187,9 +1187,12 @@ struct dentry *d_obtain_alias(struct inode *inode) spin_unlock(&tmp->d_lock); spin_unlock(&dcache_lock); + security_d_instantiate(tmp, inode); return tmp; out_iput: + if (res && !IS_ERR(res)) + security_d_instantiate(res, inode); iput(inode); return res; } -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/