SELinux: Return correct context for SO_PEERSEC

Fix SO_PEERSEC for tcp sockets to return the security context of
the peer (as represented by the SA from the peer) as opposed to the
SA used by the local/source socket.

Signed-off-by: Venkat Yekkirala <vyekkirala@TrustedCS.com>
Signed-off-by: James Morris <jmorris@namei.org>

3 files changed, 26 insertions, 47 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 28ee187ed224..5bbd599a4471 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3535,8 +3535,10 @@ static int selinux_socket_getpeersec_stream(struct socket *sock, char __user *op
         }
         else if (isec->sclass == SECCLASS_TCP_SOCKET) {
                 peer_sid = selinux_netlbl_socket_getpeersec_stream(sock);
-                if (peer_sid == SECSID_NULL)
-                        peer_sid = selinux_socket_getpeer_stream(sock->sk);
+                if (peer_sid == SECSID_NULL) {
+                        ssec = sock->sk->sk_security;
+                        peer_sid = ssec->peer_sid;
+                }
                 if (peer_sid == SECSID_NULL) {
                         err = -ENOPROTOOPT;
                         goto out;
@@ -3647,11 +3649,11 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
                 return 0;
         }
 
-        err = selinux_xfrm_decode_session(skb, &peersid, 0);
-        BUG_ON(err);
+        selinux_skb_xfrm_sid(skb, &peersid);
 
         if (peersid == SECSID_NULL) {
                 req->secid = sksec->sid;
+                req->peer_secid = 0;
                 return 0;
         }
 
@@ -3660,6 +3662,7 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
                 return err;
 
         req->secid = newsid;
+        req->peer_secid = peersid;
         return 0;
 }
 
@@ -3669,6 +3672,7 @@ static void selinux_inet_csk_clone(struct sock *newsk,
         struct sk_security_struct *newsksec = newsk->sk_security;
 
         newsksec->sid = req->secid;
+        newsksec->peer_sid = req->peer_secid;
         /* NOTE: Ideally, we should also get the isec->sid for the
            new socket in sync, but we don't have the isec available yet.
            So we will wait until sock_graft to do it, by which
@@ -3677,6 +3681,14 @@ static void selinux_inet_csk_clone(struct sock *newsk,
         selinux_netlbl_sk_security_init(newsksec, req->rsk_ops->family);
 }
 
+static void selinux_inet_conn_established(struct sock *sk,
+                                struct sk_buff *skb)
+{
+        struct sk_security_struct *sksec = sk->sk_security;
+
+        selinux_skb_xfrm_sid(skb, &sksec->peer_sid);
+}
+
 static void selinux_req_classify_flow(const struct request_sock *req,
                                       struct flowi *fl)
 {
@@ -4739,6 +4751,7 @@ static struct security_operations selinux_ops = {
         .sock_graft =                   selinux_sock_graft,
         .inet_conn_request =            selinux_inet_conn_request,
         .inet_csk_clone =               selinux_inet_csk_clone,
+        .inet_conn_established =        selinux_inet_conn_established,
         .req_classify_flow =            selinux_req_classify_flow,
 
 #ifdef CONFIG_SECURITY_NETWORK_XFRM
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index 8e329ddb5e37..27502365d706 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -39,7 +39,6 @@ int selinux_xfrm_sock_rcv_skb(u32 sid, struct sk_buff *skb,
                         struct avc_audit_data *ad);
 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
                         struct avc_audit_data *ad);
-u32 selinux_socket_getpeer_stream(struct sock *sk);
 u32 selinux_socket_getpeer_dgram(struct sk_buff *skb);
 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall);
 #else
@@ -55,11 +54,6 @@ static inline int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
         return 0;
 }
 
-static inline int selinux_socket_getpeer_stream(struct sock *sk)
-{
-        return SECSID_NULL;
-}
-
 static inline int selinux_socket_getpeer_dgram(struct sk_buff *skb)
 {
         return SECSID_NULL;
@@ -71,4 +65,10 @@ static inline int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int
 }
 #endif
 
+static inline void selinux_skb_xfrm_sid(struct sk_buff *skb, u32 *sid)
+{
+        int err = selinux_xfrm_decode_session(skb, sid, 0);
+        BUG_ON(err);
+}
+
 #endif /* _SELINUX_XFRM_H_ */
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index 4d5a043cdfa1..8fef74271f22 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -184,7 +184,8 @@ int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
 }
 
 /*
- * LSM hook implementation that determines the sid for the session.
+ * LSM hook implementation that checks and/or returns the xfrm sid for the
+ * incoming packet.
  */
 
 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
@@ -403,43 +404,8 @@ void selinux_xfrm_state_free(struct xfrm_state *x)
 }
 
 /*
- * SELinux internal function to retrieve the context of a connected
- * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
- * association used to connect to the remote socket.
- *
- * Retrieve via getsockopt SO_PEERSEC.
- */
-u32 selinux_socket_getpeer_stream(struct sock *sk)
-{
-        struct dst_entry *dst, *dst_test;
-        u32 peer_sid = SECSID_NULL;
-
-        if (sk->sk_state != TCP_ESTABLISHED)
-                goto out;
-
-        dst = sk_dst_get(sk);
-        if (!dst)
-                goto out;
-
-        for (dst_test = dst; dst_test != 0;
-             dst_test = dst_test->child) {
-                struct xfrm_state *x = dst_test->xfrm;
-
-                if (x && selinux_authorizable_xfrm(x)) {
-                        struct xfrm_sec_ctx *ctx = x->security;
-                        peer_sid = ctx->ctx_sid;
-                        break;
-                }
-        }
-        dst_release(dst);
-
-out:
-        return peer_sid;
-}
-
-/*
  * SELinux internal function to retrieve the context of a UDP packet
- * based on its security association used to connect to the remote socket.
+ * based on its security association.
  *
  * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
  * type SCM_SECURITY.