smack: introduce a special case for tmpfs in smack_d_instantiate()

Files created with __shmem_file_stup() appear to have somewhat fake
dentries which make them look like root directories and not get
the label the current process or ("*") star meant for tmpfs files.

Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 048d92e81a34..2160e88a2e4e 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3036,7 +3036,8 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
          * of the superblock.
          */
         if (opt_dentry->d_parent == opt_dentry) {
-                if (sbp->s_magic == CGROUP_SUPER_MAGIC) {
+                switch (sbp->s_magic) {
+                case CGROUP_SUPER_MAGIC:
                         /*
                          * The cgroup filesystem is never mounted,
                          * so there's no opportunity to set the mount
@@ -3044,8 +3045,19 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
                          */
                         sbsp->smk_root = &smack_known_star;
                         sbsp->smk_default = &smack_known_star;
+                        isp->smk_inode = sbsp->smk_root;
+                        break;
+                case TMPFS_MAGIC:
+                        /*
+                         * What about shmem/tmpfs anonymous files with dentry
+                         * obtained from d_alloc_pseudo()?
+                         */
+                        isp->smk_inode = smk_of_current();
+                        break;
+                default:
+                        isp->smk_inode = sbsp->smk_root;
+                        break;
                 }
-                isp->smk_inode = sbsp->smk_root;
                 isp->smk_flags |= SMK_INODE_INSTANT;
                 goto unlockandout;
         }