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Subject[PATCH 4.9 115/129] ovl: filter of trusted xattr results in audit
Date
From: Mark Salyzyn <salyzyn@android.com>

commit 5c2e9f346b815841f9bed6029ebcb06415caf640 upstream.

When filtering xattr list for reading, presence of trusted xattr
results in a security audit log. However, if there is other content
no errno will be set, and if there isn't, the errno will be -ENODATA
and not -EPERM as is usually associated with a lack of capability.
The check does not block the request to list the xattrs present.

Switch to ns_capable_noaudit to reflect a more appropriate check.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: linux-security-module@vger.kernel.org
Cc: kernel-team@android.com
Cc: stable@vger.kernel.org # v3.18+
Fixes: a082c6f680da ("ovl: filter trusted xattr for non-admin")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/overlayfs/inode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -234,7 +234,8 @@ static bool ovl_can_list(const char *s)
return true;

/* Never list trusted.overlay, list other trusted for superuser only */
- return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
+ return !ovl_is_private_xattr(s) &&
+ ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN);
}

ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)

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