[PATCH] selinux: add hooks for key subsystem

Introduce SELinux hooks to support the access key retention subsystem
within the kernel.  Incorporate new flask headers from a modified version
of the SELinux reference policy, with support for the new security class
representing retained keys.  Extend the "key_alloc" security hook with a
task parameter representing the intended ownership context for the key
being allocated.  Attach security information to root's default keyrings
within the SELinux initialization routine.

Has passed David's testsuite.

Signed-off-by: Michael LeMay <mdlemay@epoch.ncsc.mil>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 54adc9d31e92..524915dfda64 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4252,6 +4252,57 @@ static int selinux_setprocattr(struct task_struct *p,
 	return size;
 }
 
+#ifdef CONFIG_KEYS
+
+static int selinux_key_alloc(struct key *k, struct task_struct *tsk)
+{
+	struct task_security_struct *tsec = tsk->security;
+	struct key_security_struct *ksec;
+
+	ksec = kzalloc(sizeof(struct key_security_struct), GFP_KERNEL);
+	if (!ksec)
+		return -ENOMEM;
+
+	ksec->obj = k;
+	ksec->sid = tsec->sid;
+	k->security = ksec;
+
+	return 0;
+}
+
+static void selinux_key_free(struct key *k)
+{
+	struct key_security_struct *ksec = k->security;
+
+	k->security = NULL;
+	kfree(ksec);
+}
+
+static int selinux_key_permission(key_ref_t key_ref,
+			    struct task_struct *ctx,
+			    key_perm_t perm)
+{
+	struct key *key;
+	struct task_security_struct *tsec;
+	struct key_security_struct *ksec;
+
+	key = key_ref_to_ptr(key_ref);
+
+	tsec = ctx->security;
+	ksec = key->security;
+
+	/* if no specific permissions are requested, we skip the
+	   permission check. No serious, additional covert channels
+	   appear to be created. */
+	if (perm == 0)
+		return 0;
+
+	return avc_has_perm(tsec->sid, ksec->sid,
+			    SECCLASS_KEY, perm, NULL);
+}
+
+#endif
+
 static struct security_operations selinux_ops = {
 	.ptrace =			selinux_ptrace,
 	.capget =			selinux_capget,
@@ -4406,6 +4457,12 @@ static struct security_operations selinux_ops = {
 	.xfrm_state_delete_security =	selinux_xfrm_state_delete,
 	.xfrm_policy_lookup = 		selinux_xfrm_policy_lookup,
 #endif
+
+#ifdef CONFIG_KEYS
+	.key_alloc =                    selinux_key_alloc,
+	.key_free =                     selinux_key_free,
+	.key_permission =               selinux_key_permission,
+#endif
 };
 
 static __init int selinux_init(void)
@@ -4441,6 +4498,13 @@ static __init int selinux_init(void)
 	} else {
 		printk(KERN_INFO "SELinux:  Starting in permissive mode\n");
 	}
+
+#ifdef CONFIG_KEYS
+	/* Add security information to initial keyrings */
+	security_key_alloc(&root_user_keyring, current);
+	security_key_alloc(&root_session_keyring, current);
+#endif
+
 	return 0;
 }