[PATCH] Keys: Add LSM hooks for key management [try #3]

The attached patch adds LSM hooks for key management facilities. The notable
changes are:

 (1) The key struct now supports a security pointer for the use of security
     modules. This will permit key labelling and restrictions on which
     programs may access a key.

 (2) Security modules get a chance to note (or abort) the allocation of a key.

 (3) The key permission checking can now be enhanced by the security modules;
     the permissions check consults LSM if all other checks bear out.

 (4) The key permissions checking functions now return an error code rather
     than a boolean value.

 (5) An extra permission has been added to govern the modification of
     attributes (UID, GID, permissions).

Note that there isn't an LSM hook specifically for each keyctl() operation,
but rather the permissions hook allows control of individual operations based
on the permission request bits.

Key management access control through LSM is enabled by automatically if both
CONFIG_KEYS and CONFIG_SECURITY are enabled.

This should be applied on top of the patch ensubjected:

	[PATCH] Keys: Possessor permissions should be additive

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/include/linux/security.h b/include/linux/security.h
index 607ee209ea3..f7e0ae01871 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -30,6 +30,7 @@
 #include <linux/shm.h>
 #include <linux/msg.h>
 #include <linux/sched.h>
+#include <linux/key.h>
 
 struct ctl_table;
 
@@ -788,6 +789,27 @@ struct swap_info_struct;
  * @sk_free_security:
  *      Deallocate security structure.
  *
+ * Security hooks affecting all Key Management operations
+ *
+ * @key_alloc:
+ *      Permit allocation of a key and assign security data. Note that key does
+ *      not have a serial number assigned at this point.
+ *      @key points to the key.
+ *      Return 0 if permission is granted, -ve error otherwise.
+ * @key_free:
+ *      Notification of destruction; free security data.
+ *      @key points to the key.
+ *      No return value.
+ * @key_permission:
+ *      See whether a specific operational right is granted to a process on a
+ *      key.
+ *      @key_ref refers to the key (key pointer + possession attribute bit).
+ *      @context points to the process to provide the context against which to
+ *       evaluate the security data on the key.
+ *      @perm describes the combination of permissions required of this key.
+ *      Return 1 if permission granted, 0 if permission denied and -ve it the
+ *      normal permissions model should be effected.
+ *
  * Security hooks affecting all System V IPC operations.
  *
  * @ipc_permission:
@@ -1216,6 +1238,17 @@ struct security_operations {
         int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority);
         void (*sk_free_security) (struct sock *sk);
 #endif  /* CONFIG_SECURITY_NETWORK */
+
+        /* key management security hooks */
+#ifdef CONFIG_KEYS
+        int (*key_alloc)(struct key *key);
+        void (*key_free)(struct key *key);
+        int (*key_permission)(key_ref_t key_ref,
+                              struct task_struct *context,
+                              key_perm_t perm);
+
+#endif  /* CONFIG_KEYS */
+
 };
 
 /* global variables */
@@ -2764,5 +2797,45 @@ static inline void security_sk_free(struct sock *sk)
 }
 #endif  /* CONFIG_SECURITY_NETWORK */
 
+#ifdef CONFIG_KEYS
+#ifdef CONFIG_SECURITY
+static inline int security_key_alloc(struct key *key)
+{
+        return security_ops->key_alloc(key);
+}
+
+static inline void security_key_free(struct key *key)
+{
+        security_ops->key_free(key);
+}
+
+static inline int security_key_permission(key_ref_t key_ref,
+                                          struct task_struct *context,
+                                          key_perm_t perm)
+{
+        return security_ops->key_permission(key_ref, context, perm);
+}
+
+#else
+
+static inline int security_key_alloc(struct key *key)
+{
+        return 0;
+}
+
+static inline void security_key_free(struct key *key)
+{
+}
+
+static inline int security_key_permission(key_ref_t key_ref,
+                                          struct task_struct *context,
+                                          key_perm_t perm)
+{
+        return 0;
+}
+
+#endif
+#endif /* CONFIG_KEYS */
+
 #endif /* ! __LINUX_SECURITY_H */