Smack: recursive tramsmute

The transmuting directory feature of Smack requires that
the transmuting attribute be explicitly set in all cases.
It seems the users of this facility would expect that the
transmuting attribute be inherited by subdirectories that
are created in a transmuting directory. This does not seem
to add any additional complexity to the understanding of
how the system works.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 2ad00657b80198f3cd9f8acbd20a5eed31f0f218..49e6ee215d5b31b671161861e345f77d279dad67 100644 (file)
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -66,6 +66,7 @@ struct task_smack {
 
 #define        SMK_INODE_INSTANT       0x01    /* inode is instantiated */
 #define        SMK_INODE_TRANSMUTE     0x02    /* directory is transmuting */
+#define        SMK_INODE_CHANGED       0x04    /* smack was transmuted */
 
 /*
  * A label access rule.

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index cd667b4089a52ace663ce24f86f939c80c21dbbf..c9d2fd99ff0bf156ad96f0d73fa376e3314225d6 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -556,6 +556,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
                                     void **value, size_t *len)
 {
        struct smack_known *skp;
+       struct inode_smack *issp = inode->i_security;
        char *csp = smk_of_current();
        char *isp = smk_of_inode(inode);
        char *dsp = smk_of_inode(dir);
@@ -577,10 +578,13 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
                 * If the access rule allows transmutation and
                 * the directory requests transmutation then
                 * by all means transmute.
+                * Mark the inode as changed.
                 */
                if (may > 0 && ((may & MAY_TRANSMUTE) != 0) &&
-                   smk_inode_transmutable(dir))
+                   smk_inode_transmutable(dir)) {
                        isp = dsp;
+                       issp->smk_flags |= SMK_INODE_CHANGED;
+               }
 
                *value = kstrdup(isp, GFP_KERNEL);
                if (*value == NULL)
@@ -2550,6 +2554,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
        char *final;
        char trattr[TRANS_TRUE_SIZE];
        int transflag = 0;
+       int rc;
        struct dentry *dp;
 
        if (inode == NULL)
@@ -2668,17 +2673,38 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
                 */
                dp = dget(opt_dentry);
                fetched = smk_fetch(XATTR_NAME_SMACK, inode, dp);
-               if (fetched != NULL) {
+               if (fetched != NULL)
                        final = fetched;
-                       if (S_ISDIR(inode->i_mode)) {
-                               trattr[0] = '\0';
-                               inode->i_op->getxattr(dp,
+
+               /*
+                * Transmuting directory
+                */
+               if (S_ISDIR(inode->i_mode)) {
+                       /*
+                        * If this is a new directory and the label was
+                        * transmuted when the inode was initialized
+                        * set the transmute attribute on the directory
+                        * and mark the inode.
+                        *
+                        * If there is a transmute attribute on the
+                        * directory mark the inode.
+                        */
+                       if (isp->smk_flags & SMK_INODE_CHANGED) {
+                               isp->smk_flags &= ~SMK_INODE_CHANGED;
+                               rc = inode->i_op->setxattr(dp,
                                        XATTR_NAME_SMACKTRANSMUTE,
-                                       trattr, TRANS_TRUE_SIZE);
-                               if (strncmp(trattr, TRANS_TRUE,
-                                           TRANS_TRUE_SIZE) == 0)
-                                       transflag = SMK_INODE_TRANSMUTE;
+                                       TRANS_TRUE, TRANS_TRUE_SIZE,
+                                       0);
+                       } else {
+                               rc = inode->i_op->getxattr(dp,
+                                       XATTR_NAME_SMACKTRANSMUTE, trattr,
+                                       TRANS_TRUE_SIZE);
+                               if (rc >= 0 && strncmp(trattr, TRANS_TRUE,
+                                                      TRANS_TRUE_SIZE) != 0)
+                                       rc = -EINVAL;
                        }
+                       if (rc >= 0)
+                               transflag = SMK_INODE_TRANSMUTE;
                }
                isp->smk_task = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp);
                isp->smk_mmap = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp);