[PATCH 36/59] LSM: Limit calls to certain module hooks

[Casey Schaufler <casey@schaufler-ca.com>]

LSM hooks dealing with security context strings should
only be called for one security module. Add call macros
that invoke a single module hook and us in for those cases.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 security/security.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/security/security.c b/security/security.c
index 015c38c882ba..7bf16c547010 100644
--- a/security/security.c
+++ b/security/security.c
@@ -713,6 +713,16 @@ int lsm_superblock_alloc(struct super_block *sb)
 			P->hook.FUNC(__VA_ARGS__);		\
 	} while (0)
 
+#define call_one_void_hook(FUNC, ...)				\
+	do {							\
+		struct security_hook_list *P;			\
+								\
+		hlist_for_each_entry(P, &security_hook_heads.FUNC, list) { \
+			P->hook.FUNC(__VA_ARGS__);		\
+			break;					\
+		}						\
+	} while (0)
+
 #define call_int_hook(FUNC, IRC, ...) ({			\
 	int RC = IRC;						\
 	do {							\
@@ -727,6 +737,19 @@ int lsm_superblock_alloc(struct super_block *sb)
 	RC;							\
 })
 
+#define call_one_int_hook(FUNC, IRC, ...) ({			\
+	int RC = IRC;						\
+	do {							\
+		struct security_hook_list *P;			\
+								\
+		hlist_for_each_entry(P, &security_hook_heads.FUNC, list) { \
+			RC = P->hook.FUNC(__VA_ARGS__);		\
+			break;					\
+		}						\
+	} while (0);						\
+	RC;							\
+})
+
 /* Security operations */
 
 int security_binder_set_context_mgr(struct task_struct *mgr)
@@ -1966,7 +1989,8 @@ EXPORT_SYMBOL(security_ismaclabel);
 
 int security_secid_to_secctx(struct lsm_export *l, char **secdata, u32 *seclen)
 {
-	return call_int_hook(secid_to_secctx, -EOPNOTSUPP, l, secdata, seclen);
+	return call_one_int_hook(secid_to_secctx, -EOPNOTSUPP, l, secdata,
+				 seclen);
 }
 EXPORT_SYMBOL(security_secid_to_secctx);
 
@@ -1974,13 +1998,13 @@ int security_secctx_to_secid(const char *secdata, u32 seclen,
 			     struct lsm_export *l)
 {
 	lsm_export_init(l);
-	return call_int_hook(secctx_to_secid, 0, secdata, seclen, l);
+	return call_one_int_hook(secctx_to_secid, 0, secdata, seclen, l);
 }
 EXPORT_SYMBOL(security_secctx_to_secid);
 
 void security_release_secctx(char *secdata, u32 seclen)
 {
-	call_void_hook(release_secctx, secdata, seclen);
+	call_one_void_hook(release_secctx, secdata, seclen);
 }
 EXPORT_SYMBOL(security_release_secctx);
 
@@ -2105,7 +2129,7 @@ EXPORT_SYMBOL(security_sock_rcv_skb);
 int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
 				      int __user *optlen, unsigned len)
 {
-	return call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock,
+	return call_one_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock,
 				optval, optlen, len);
 }
 
-- 
2.19.1