From: Amir Goldstein <amir73il@gmail.com>
To: Paul Moore <paul@paul-moore.com>
Cc: Michael Labriola <michael.d.labriola@gmail.com>,
Jonathan Lebon <jlebon@redhat.com>,
Stephen Smalley <stephen.smalley.work@gmail.com>,
Miklos Szeredi <miklos@szeredi.hu>,
selinux@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
stable@vger.kernel.org
Subject: [PATCH] selinux: fix inconsistency between inode_getxattr and inode_listsecurity
Date: Sat, 19 Dec 2020 12:05:27 +0200 [thread overview]
Message-ID: <20201219100527.16060-1-amir73il@gmail.com> (raw)
When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr
calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will
intercept in inode_getxattr hooks.
When selinux LSM is installed but not initialized, it will list the
security.selinux xattr in inode_listsecurity, but will not intercept it
in inode_getxattr. This results in -ENODATA for a getxattr call for an
xattr returned by listxattr.
This situation was manifested as overlayfs failure to copy up lower
files from squashfs when selinux is built-in but not initialized,
because ovl_copy_xattr() iterates the lower inode xattrs by
vfs_listxattr() and vfs_getxattr().
Match the logic of inode_listsecurity to that of inode_getxattr and
do not list the security.selinux xattr if selinux is not initialized.
Reported-by: Michael Labriola <michael.d.labriola@gmail.com>
Tested-by: Michael Labriola <michael.d.labriola@gmail.com>
Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@aldarion.sourceruckus.org/
Fixes: c8e222616c7e ("selinux: allow reading labels before policy is loaded")
Cc: stable@vger.kernel.org#v5.9+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
security/selinux/hooks.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6b1826fc3658..e132e082a5af 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3406,6 +3406,10 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
{
const int len = sizeof(XATTR_NAME_SELINUX);
+
+ if (!selinux_initialized(&selinux_state))
+ return 0;
+
if (buffer && len <= buffer_size)
memcpy(buffer, XATTR_NAME_SELINUX, len);
return len;
--
2.25.1
next reply other threads:[~2020-12-19 10:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-19 10:05 Amir Goldstein [this message]
2021-01-04 9:39 ` [PATCH] selinux: fix inconsistency between inode_getxattr and inode_listsecurity Ondrej Mosnacek
2021-01-05 1:46 ` Paul Moore
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