[bpf PATCH v2] bpf: sockmap, fix crash when ipv6 sock is added

[John Fastabend <john.fastabend@gmail.com>]

This fixes a crash where we assign tcp_prot to IPv6 sockets instead
of tcpv6_prot.

Previously we overwrote the sk->prot field with tcp_prot even in the
AF_INET6 case. This patch ensures the correct tcp_prot and tcpv6_prot
are used. Further, only allow ESTABLISHED connections to join the
map per note in TLS ULP,

   /* The TLS ulp is currently supported only for TCP sockets
    * in ESTABLISHED state.
    * Supporting sockets in LISTEN state will require us
    * to modify the accept implementation to clone rather then
    * share the ulp context.
    */

Also tested with 'netserver -6' and 'netperf -H [IPv6]' as well as
'netperf -H [IPv4]'. The ESTABLISHED check resolves the previously
crashing case here.

Fixes: 174a79ff9515 ("bpf: sockmap with sk redirect support")
Reported-by: syzbot+5c063698bdbfac19f363@syzkaller.appspotmail.com
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Wei Wang <weiwan@google.com>
---
 kernel/bpf/sockmap.c |   23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 95a84b2..1c8bf18 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -41,6 +41,7 @@
 #include <linux/mm.h>
 #include <net/strparser.h>
 #include <net/tcp.h>
+#include <net/transp_v6.h>
 #include <linux/ptr_ring.h>
 #include <net/inet_common.h>
 #include <linux/sched/signal.h>
@@ -134,6 +135,8 @@ static bool bpf_tcp_stream_read(const struct sock *sk)
 }
 
 static struct proto tcp_bpf_proto;
+static struct proto tcpv6_bpf_proto;
+
 static int bpf_tcp_init(struct sock *sk)
 {
 	struct smap_psock *psock;
@@ -154,13 +157,21 @@ static int bpf_tcp_init(struct sock *sk)
 	psock->sk_proto = sk->sk_prot;
 
 	if (psock->bpf_tx_msg) {
+		tcpv6_bpf_proto.sendmsg = bpf_tcp_sendmsg;
+		tcpv6_bpf_proto.sendpage = bpf_tcp_sendpage;
+		tcpv6_bpf_proto.recvmsg = bpf_tcp_recvmsg;
+		tcpv6_bpf_proto.stream_memory_read = bpf_tcp_stream_read;
 		tcp_bpf_proto.sendmsg = bpf_tcp_sendmsg;
 		tcp_bpf_proto.sendpage = bpf_tcp_sendpage;
 		tcp_bpf_proto.recvmsg = bpf_tcp_recvmsg;
 		tcp_bpf_proto.stream_memory_read = bpf_tcp_stream_read;
 	}
 
-	sk->sk_prot = &tcp_bpf_proto;
+	if (sk->sk_family == AF_INET6)
+		sk->sk_prot = &tcpv6_bpf_proto;
+	else
+		sk->sk_prot = &tcp_bpf_proto;
+
 	rcu_read_unlock();
 	return 0;
 }
@@ -1072,6 +1083,8 @@ static int bpf_tcp_ulp_register(void)
 {
 	tcp_bpf_proto = tcp_prot;
 	tcp_bpf_proto.close = bpf_tcp_close;
+	tcpv6_bpf_proto = tcpv6_prot;
+	tcpv6_bpf_proto.close = bpf_tcp_close;
 	/* Once BPF TX ULP is registered it is never unregistered. It
 	 * will be in the ULP list for the lifetime of the system. Doing
 	 * duplicate registers is not a problem.
@@ -1689,6 +1702,14 @@ static int sock_map_ctx_update_elem(struct bpf_sock_ops_kern *skops,
 
 	sock = skops->sk;
 
+	/* ULPs are currently supported only for TCP sockets in ESTABLISHED
+	 * state. Supporting sockets in LISTEN state will require us to
+	 * modify the accept implementation to clone rather then share the
+	 * ulp context.
+	 */
+	if (sock->sk_state != TCP_ESTABLISHED)
+		return -ENOTSUPP;
+
 	/* 1. If sock map has BPF programs those will be inherited by the
 	 * sock being added. If the sock is already attached to BPF programs
 	 * this results in an error.