Smack: getting the Smack security context of keys
With this commit, the LSM Smack implements the LSM
side part of the system call keyctl with the action
code KEYCTL_GET_SECURITY.
It is now possible to get the context of, for example,
the user session key using the command "keyctl security @s".
The original patch has been modified for merge.
Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index a097dc7d..e2d1a7b 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4000,6 +4000,36 @@
rc = smk_bu_note("key access", tkp, keyp->security, request, rc);
return rc;
}
+
+/*
+ * smack_key_getsecurity - Smack label tagging the key
+ * @key points to the key to be queried
+ * @_buffer points to a pointer that should be set to point to the
+ * resulting string (if no label or an error occurs).
+ * Return the length of the string (including terminating NUL) or -ve if
+ * an error.
+ * May also return 0 (and a NULL buffer pointer) if there is no label.
+ */
+static int smack_key_getsecurity(struct key *key, char **_buffer)
+{
+ struct smack_known *skp = key->security;
+ size_t length;
+ char *copy;
+
+ if (key->security == NULL) {
+ *_buffer = NULL;
+ return 0;
+ }
+
+ copy = kstrdup(skp->smk_known, GFP_KERNEL);
+ if (copy == NULL)
+ return -ENOMEM;
+ length = strlen(copy) + 1;
+
+ *_buffer = copy;
+ return length;
+}
+
#endif /* CONFIG_KEYS */
/*
@@ -4324,6 +4354,7 @@
.key_alloc = smack_key_alloc,
.key_free = smack_key_free,
.key_permission = smack_key_permission,
+ .key_getsecurity = smack_key_getsecurity,
#endif /* CONFIG_KEYS */
/* Audit hooks */