[PATCH net 4/4] security: implement sctp_assoc_established hook in selinux

[Xin Long]

Different from selinux_inet_conn_established(), it also gives the
secid to asoc->peer_secid in selinux_sctp_assoc_established(),
as one UDP-type socket may have more than one asocs.

Note that peer_secid in asoc will save the peer secid for this
asoc connection, and peer_sid in sksec will just keep the peer
secid for the latest connection. So the right use should be do
peeloff for UDP-type socket if there will be multiple asocs in
one socket, so that the peeloff socket has the right label for
its asoc.

Fixes: 72e89f50084c ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad at redhat.com>
Signed-off-by: Xin Long <lucien.xin at gmail.com>
---
 security/selinux/hooks.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f025fc00421b..793fdcbc68bd 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5525,6 +5525,21 @@ static void selinux_sctp_sk_clone(struct sctp_association *asoc, struct sock *sk
 	selinux_netlbl_sctp_sk_clone(sk, newsk);
 }
 
+static void selinux_sctp_assoc_established(struct sctp_association *asoc,
+					   struct sk_buff *skb)
+{
+	struct sk_security_struct *sksec = asoc->base.sk->sk_security;
+	u16 family = asoc->base.sk->sk_family;
+
+	/* handle mapped IPv4 packets arriving via IPv6 sockets */
+	if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
+		family = PF_INET;
+
+	selinux_skb_peerlbl_sid(skb, family, &sksec->peer_sid);
+	asoc->secid = sksec->sid;
+	asoc->peer_secid = sksec->peer_sid;
+}
+
 static int selinux_inet_conn_request(const struct sock *sk, struct sk_buff *skb,
 				     struct request_sock *req)
 {
@@ -7290,6 +7305,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sctp_assoc_request, selinux_sctp_assoc_request),
 	LSM_HOOK_INIT(sctp_sk_clone, selinux_sctp_sk_clone),
 	LSM_HOOK_INIT(sctp_bind_connect, selinux_sctp_bind_connect),
+	LSM_HOOK_INIT(sctp_assoc_established, selinux_sctp_assoc_established),
 	LSM_HOOK_INIT(inet_conn_request, selinux_inet_conn_request),
 	LSM_HOOK_INIT(inet_csk_clone, selinux_inet_csk_clone),
 	LSM_HOOK_INIT(inet_conn_established, selinux_inet_conn_established),
-- 
2.27.0