A socket which has sk_family set to PF_INET6 is able to receive not
only IPv6 but also IPv4 traffic (IPv4-mapped IPv6 addresses).

Prior to this change, the smk_skb_to_addr_ipv6() could have been
called for socket buffers containing IPv4 packets.

Signed-off-by: Piotr Sawicki <redacted>
---
 ?security/smack/smack_lsm.c | 12 ++++++++----
 ?1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 19de675..1315de4 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c

@@ -3924,15 +3924,19 @@ static int smack_socket_sock_rcv_skb(struct sock 

*sk, struct sk_buff *skb)
 ???? struct smack_known *skp = NULL;
 ???? int rc = 0;
 ???? struct smk_audit_info ad;
+??? u16 family = sk->sk_family;
 ?#ifdef CONFIG_AUDIT
 ???? struct lsm_network_audit net;
 ?#endif
 ?#if IS_ENABLED(CONFIG_IPV6)
 ???? struct sockaddr_in6 sadd;
 ???? int proto;
+
+??? if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
+??? ??? family = PF_INET;
 ?#endif /* CONFIG_IPV6 */

-??? switch (sk->sk_family) {
+??? switch (family) {
 ???? case PF_INET:
 ?#ifdef CONFIG_SECURITY_SMACK_NETFILTER
 ???? ??? /*

@@ -3950,7 +3954,7 @@ static int smack_socket_sock_rcv_skb(struct sock 

*sk, struct sk_buff *skb)
 ???? ??? ?*/
 ???? ??? netlbl_secattr_init(&secattr);

-??? ??? rc = netlbl_skbuff_getattr(skb, sk->sk_family, &secattr);
+??? ??? rc = netlbl_skbuff_getattr(skb, family, &secattr);
 ???? ??? if (rc == 0)
 ???? ??? ??? skp = smack_from_secattr(&secattr, ssp);
 ???? ??? else

@@ -3963,7 +3967,7 @@ static int smack_socket_sock_rcv_skb(struct sock 

*sk, struct sk_buff *skb)
 ?#endif
 ?#ifdef CONFIG_AUDIT
 ???? ??? smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
-??? ??? ad.a.u.net->family = sk->sk_family;
+??? ??? ad.a.u.net->family = family;
 ???? ??? ad.a.u.net->netif = skb->skb_iif;
 ???? ??? ipv4_skb_to_auditdata(skb, &ad.a, NULL);
 ?#endif

@@ -3977,7 +3981,7 @@ static int smack_socket_sock_rcv_skb(struct sock 

*sk, struct sk_buff *skb)
 ???? ??? rc = smk_bu_note("IPv4 delivery", skp, ssp->smk_in,
 ???? ??? ??? ??? ??? MAY_WRITE, rc);
 ???? ??? if (rc != 0)
-??? ??? ??? netlbl_skbuff_err(skb, sk->sk_family, rc, 0);
+??? ??? ??? netlbl_skbuff_err(skb, family, rc, 0);
 ???? ??? break;
 ?#if IS_ENABLED(CONFIG_IPV6)
 ???? case PF_INET6:
-- 
2.7.4
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