SELinux: peer secid consolidation for external network labeling

Now that labeled IPsec makes use of the peer_sid field in the
sk_security_struct we can remove a lot of the special cases between labeled
IPsec and NetLabel.  In addition, create a new function,
security_skb_extlbl_sid(), which we can use in several places to get the
security context of the packet's external label which allows us to further
simplify the code in a few places.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

6 files changed, 52 insertions, 150 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 975c0dfb5a11..a29d78d3f44c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3574,27 +3574,16 @@ static int selinux_socket_getpeersec_stream(struct socket *sock, char __user *op
         u32 scontext_len;
         struct sk_security_struct *ssec;
         struct inode_security_struct *isec;
-        u32 peer_sid = 0;
+        u32 peer_sid = SECSID_NULL;
 
         isec = SOCK_INODE(sock)->i_security;
 
-        /* if UNIX_STREAM check peer_sid, if TCP check dst for labelled sa */
-        if (isec->sclass == SECCLASS_UNIX_STREAM_SOCKET) {
+        if (isec->sclass == SECCLASS_UNIX_STREAM_SOCKET ||
+            isec->sclass == SECCLASS_TCP_SOCKET) {
                 ssec = sock->sk->sk_security;
                 peer_sid = ssec->peer_sid;
         }
-        else if (isec->sclass == SECCLASS_TCP_SOCKET) {
-                peer_sid = selinux_netlbl_socket_getpeersec_stream(sock);
-                if (peer_sid == SECSID_NULL) {
-                        ssec = sock->sk->sk_security;
-                        peer_sid = ssec->peer_sid;
-                }
-                if (peer_sid == SECSID_NULL) {
-                        err = -ENOPROTOOPT;
-                        goto out;
-                }
-        }
-        else {
+        if (peer_sid == SECSID_NULL) {
                 err = -ENOPROTOOPT;
                 goto out;
         }
@@ -3626,13 +3615,12 @@ static int selinux_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *
         u32 peer_secid = SECSID_NULL;
         int err = 0;
 
-        if (sock && (sock->sk->sk_family == PF_UNIX))
+        if (sock && sock->sk->sk_family == PF_UNIX)
                 selinux_get_inode_sid(SOCK_INODE(sock), &peer_secid);
-        else if (skb) {
-                peer_secid = selinux_netlbl_socket_getpeersec_dgram(skb);
-                if (peer_secid == SECSID_NULL)
-                        peer_secid = selinux_socket_getpeer_dgram(skb);
-        }
+        else if (skb)
+                security_skb_extlbl_sid(skb,
+                                        SECINITSID_UNLABELED,
+                                        &peer_secid);
 
         if (peer_secid == SECSID_NULL)
                 err = -EINVAL;
@@ -3693,17 +3681,10 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
         u32 newsid;
         u32 peersid;
 
-        newsid = selinux_netlbl_inet_conn_request(skb, sksec->sid);
-        if (newsid != SECSID_NULL) {
-                req->secid = newsid;
-                return 0;
-        }
-
-        selinux_skb_xfrm_sid(skb, &peersid);
-
+        security_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &peersid);
         if (peersid == SECSID_NULL) {
                 req->secid = sksec->sid;
-                req->peer_secid = 0;
+                req->peer_secid = SECSID_NULL;
                 return 0;
         }
 
@@ -3738,7 +3719,7 @@ static void selinux_inet_conn_established(struct sock *sk,
 {
         struct sk_security_struct *sksec = sk->sk_security;
 
-        selinux_skb_xfrm_sid(skb, &sksec->peer_sid);
+        security_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &sksec->peer_sid);
 }
 
 static void selinux_req_classify_flow(const struct request_sock *req,
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index 1ef79172cc8c..015f697e925f 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -8,6 +8,7 @@
 #ifndef _SELINUX_SECURITY_H_
 #define _SELINUX_SECURITY_H_
 
+#include <linux/skbuff.h>
 #include "flask.h"
 
 #define SECSID_NULL                     0x00000000 /* unspecified SID */
@@ -80,6 +81,8 @@ int security_netif_sid(char *name, u32 *if_sid,
 int security_node_sid(u16 domain, void *addr, u32 addrlen,
         u32 *out_sid);
 
+void security_skb_extlbl_sid(struct sk_buff *skb, u32 base_sid, u32 *sid);
+
 int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
                                  u16 tclass);
 
diff --git a/security/selinux/include/selinux_netlabel.h b/security/selinux/include/selinux_netlabel.h
index 57943f4a8f90..2a732c9033e3 100644
--- a/security/selinux/include/selinux_netlabel.h
+++ b/security/selinux/include/selinux_netlabel.h
@@ -38,14 +38,12 @@
 
 #ifdef CONFIG_NETLABEL
 void selinux_netlbl_cache_invalidate(void);
+int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u32 base_sid, u32 *sid);
 int selinux_netlbl_socket_post_create(struct socket *sock);
 void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock);
-u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb, u32 sock_sid);
 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
                                 struct sk_buff *skb,
                                 struct avc_audit_data *ad);
-u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock);
-u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb);
 void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
                                       int family);
 void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
@@ -62,6 +60,14 @@ static inline void selinux_netlbl_cache_invalidate(void)
         return;
 }
 
+static inline int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
+                                               u32 base_sid,
+                                               u32 *sid)
+{
+        *sid = SECSID_NULL;
+        return 0;
+}
+
 static inline int selinux_netlbl_socket_post_create(struct socket *sock)
 {
         return 0;
@@ -73,12 +79,6 @@ static inline void selinux_netlbl_sock_graft(struct sock *sk,
         return;
 }
 
-static inline u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb,
-                                                   u32 sock_sid)
-{
-        return SECSID_NULL;
-}
-
 static inline int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
                                               struct sk_buff *skb,
                                               struct avc_audit_data *ad)
@@ -86,16 +86,6 @@ static inline int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
         return 0;
 }
 
-static inline u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock)
-{
-        return SECSID_NULL;
-}
-
-static inline u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb)
-{
-        return SECSID_NULL;
-}
-
 static inline void selinux_netlbl_sk_security_reset(
                                                struct sk_security_struct *ssec,
                                                int family)
diff --git a/security/selinux/include/xfrm.h b/security/selinux/include/xfrm.h
index ebd7246a4be5..161eb571c82d 100644
--- a/security/selinux/include/xfrm.h
+++ b/security/selinux/include/xfrm.h
@@ -36,7 +36,6 @@ 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, u8 proto);
-u32 selinux_socket_getpeer_dgram(struct sk_buff *skb);
 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall);
 #else
 static inline int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
@@ -51,10 +50,6 @@ static inline int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
         return 0;
 }
 
-static inline int selinux_socket_getpeer_dgram(struct sk_buff *skb)
-{
-        return SECSID_NULL;
-}
 static inline int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
 {
         *sid = SECSID_NULL;
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index b66b454fe72b..b43dd803fd5e 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -54,6 +54,7 @@
 #include "mls.h"
 #include "objsec.h"
 #include "selinux_netlabel.h"
+#include "xfrm.h"
 
 extern void selnl_notify_policyload(u32 seqno);
 unsigned int policydb_loaded_version;
@@ -2191,6 +2192,32 @@ void selinux_audit_set_callback(int (*callback)(void))
         aurule_callback = callback;
 }
 
+/**
+ * security_skb_extlbl_sid - Determine the external label of a packet
+ * @skb: the packet
+ * @base_sid: the SELinux SID to use as a context for MLS only external labels
+ * @sid: the packet's SID
+ *
+ * Description:
+ * Check the various different forms of external packet labeling and determine
+ * the external SID for the packet.
+ *
+ */
+void security_skb_extlbl_sid(struct sk_buff *skb, u32 base_sid, u32 *sid)
+{
+        u32 xfrm_sid;
+        u32 nlbl_sid;
+
+        selinux_skb_xfrm_sid(skb, &xfrm_sid);
+        if (selinux_netlbl_skbuff_getsid(skb,
+                                         (xfrm_sid == SECSID_NULL ?
+                                          base_sid : xfrm_sid),
+                                         &nlbl_sid) != 0)
+                nlbl_sid = SECSID_NULL;
+
+        *sid = (nlbl_sid == SECSID_NULL ? xfrm_sid : nlbl_sid);
+}
+
 #ifdef CONFIG_NETLABEL
 /*
  * This is the structure we store inside the NetLabel cache block.
@@ -2408,9 +2435,7 @@ netlbl_secattr_to_sid_return_cleanup:
  * assign to the packet.  Returns zero on success, negative values on failure.
  *
  */
-static int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
-                                        u32 base_sid,
-                                        u32 *sid)
+int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u32 base_sid, u32 *sid)
 {
         int rc;
         struct netlbl_lsm_secattr secattr;
@@ -2616,29 +2641,6 @@ void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
 }
 
 /**
- * selinux_netlbl_inet_conn_request - Handle a new connection request
- * @skb: the packet
- * @sock_sid: the SID of the parent socket
- *
- * Description:
- * If present, use the security attributes of the packet in @skb and the
- * parent sock's SID to arrive at a SID for the new child sock.  Returns the
- * SID of the connection or SECSID_NULL on failure.
- *
- */
-u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb, u32 sock_sid)
-{
-        int rc;
-        u32 peer_sid;
-
-        rc = selinux_netlbl_skbuff_getsid(skb, sock_sid, &peer_sid);
-        if (rc != 0)
-                return SECSID_NULL;
-
-        return peer_sid;
-}
-
-/**
  * selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
  * @inode: the file descriptor's inode
  * @mask: the permission mask
@@ -2728,42 +2730,6 @@ int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 }
 
 /**
- * selinux_netlbl_socket_getpeersec_stream - Return the connected peer's SID
- * @sock: the socket
- *
- * Description:
- * Examine @sock to find the connected peer's SID.  Returns the SID on success
- * or SECSID_NULL on error.
- *
- */
-u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock)
-{
-        struct sk_security_struct *sksec = sock->sk->sk_security;
-        return sksec->peer_sid;
-}
-
-/**
- * selinux_netlbl_socket_getpeersec_dgram - Return the SID of a NetLabel packet
- * @skb: the packet
- *
- * Description:
- * Examine @skb to find the SID assigned to it by NetLabel.  Returns the SID on
- * success, SECSID_NULL on error.
- *
- */
-u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb)
-{
-        int peer_sid;
-
-        if (selinux_netlbl_skbuff_getsid(skb,
-                                         SECINITSID_UNLABELED,
-                                         &peer_sid) != 0)
-                return SECSID_NULL;
-
-        return peer_sid;
-}
-
-/**
  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
  * @sock: the socket
  * @level: the socket level or protocol
diff --git a/security/selinux/xfrm.c b/security/selinux/xfrm.c
index 9b777140068f..bd8d1ef40a90 100644
--- a/security/selinux/xfrm.c
+++ b/security/selinux/xfrm.c
@@ -372,39 +372,6 @@ void selinux_xfrm_state_free(struct xfrm_state *x)
                 kfree(ctx);
 }
 
-/*
- * SELinux internal function to retrieve the context of a UDP packet
- * based on its security association.
- *
- * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
- * type SCM_SECURITY.
- */
-u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
-{
-        struct sec_path *sp;
-
-        if (skb == NULL)
-                return SECSID_NULL;
-
-        if (skb->sk->sk_protocol != IPPROTO_UDP)
-                return SECSID_NULL;
-
-        sp = skb->sp;
-        if (sp) {
-                int i;
-
-                for (i = sp->len-1; i >= 0; i--) {
-                        struct xfrm_state *x = sp->xvec[i];
-                        if (selinux_authorizable_xfrm(x)) {
-                                struct xfrm_sec_ctx *ctx = x->security;
-                                return ctx->ctx_sid;
-                        }
-                }
-        }
-
-        return SECSID_NULL;
-}
-
  /*
   * LSM hook implementation that authorizes deletion of labeled SAs.
   */