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fs-call-security_d_instantiate-in-d_obtain_alias (#662344)

This commit is contained in:
Kyle McMartin 2010-12-18 10:50:03 -05:00
parent 7907a3cd74
commit 5bd23aa290
2 changed files with 74 additions and 0 deletions
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65
fs-call-security_d_instantiate-in-d_obtain_alias.patch Normal file
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@ -0,0 +1,65 @@
From linux-fsdevel-owner@vger.kernel.org Thu Nov 18 21:03:11 2010
From: Josef Bacik <josef@redhat.com>
To: linux-fsdevel@vger.kernel.org, eparis@redhat.com,
linux-kernel@vger.kernel.org, sds@tycho.nsa.gov,
selinux@tycho.nsa.gov, bfields@fieldses.org
Subject: [PATCH] fs: call security_d_instantiate in d_obtain_alias V2
Date: Thu, 18 Nov 2010 20:52:55 -0500
Message-Id: <1290131575-2489-1-git-send-email-josef@redhat.com>
X-Mailing-List: linux-fsdevel@vger.kernel.org
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 <josef@redhat.com>
---
V1->V2:
-added second security_d_instantiate() call
fs/dcache.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 23702a9..119d489 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1201,9 +1201,12 @@ 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;
}
--
1.6.6.1
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9
kernel.spec
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@ -907,6 +907,9 @@ Patch13921: can-bcm-fix-minor-heap-overflow.patch
# Allow AF_PACKET to be less of a pig with contiguous ram
Patch13922: patch-2.6.38-afpacket-vmalloc.patch
# rhbz#662344
Patch12922: fs-call-security_d_instantiate-in-d_obtain_alias.patch
%endif
BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@ -1737,6 +1740,9 @@ ApplyPatch can-bcm-fix-minor-heap-overflow.patch
# Allow AF_PACKET to be less of a contiguous ram pig
ApplyPatch patch-2.6.38-afpacket-vmalloc.patch
# rhbz#662344
ApplyPatch fs-call-security_d_instantiate-in-d_obtain_alias.patch
# END OF PATCH APPLICATIONS
%endif
@ -2358,6 +2364,9 @@ fi
%changelog
* Sat Dec 18 2010 Kyle McMartin <kyle@redhat.com>
- Fix SELinux issues with NFS/btrfs and/or xfsdump. (#662344)
* Fri Dec 17 2010 Neil Horman <nhorman@redhat.com>
- Enhance AF_PACKET to allow non-contiguous buffer alloc (bz 637619)