Smack: fix d_instantiate logic for sockfs and pipefs

Since 4b936885a (v2.6.32) all inodes on sockfs and pipefs are disconnected.
It caused filesystem specific code in smack_d_instantiate to be skipped,
because all inodes on those pseudo filesystems were treated as root inodes.
As a result all sockfs inodes had the Smack label set to floor.

In most cases access checks for sockets use socket_smack data so the inode
label is not important. But there are special cases that were broken.
One example would be calling fcntl with F_SETOWN command on a socket fd.

Now smack_d_instantiate expects all pipefs and sockfs inodes to be
disconnected and has the logic in appropriate place.

Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 681583d66c0e94c7d7d13ad2cd2f78cf30571289..225c4ad56444adb0e2f805a6f204b77b5ee8d45d 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3486,6 +3486,13 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
                case PIPEFS_MAGIC:
                        isp->smk_inode = smk_of_current();
                        break;
+               case SOCKFS_MAGIC:
+                       /*
+                        * Socket access is controlled by the socket
+                        * structures associated with the task involved.
+                        */
+                       isp->smk_inode = &smack_known_star;
+                       break;
                default:
                        isp->smk_inode = sbsp->smk_root;
                        break;
@@ -3502,19 +3509,12 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
         */
        switch (sbp->s_magic) {
        case SMACK_MAGIC:
-       case PIPEFS_MAGIC:
-       case SOCKFS_MAGIC:
        case CGROUP_SUPER_MAGIC:
                /*
                 * Casey says that it's a little embarrassing
                 * that the smack file system doesn't do
                 * extended attributes.
                 *
-                * Casey says pipes are easy (?)
-                *
-                * Socket access is controlled by the socket
-                * structures associated with the task involved.
-                *
                 * Cgroupfs is special
                 */
                final = &smack_known_star;