netdev - [RFCv2 bpf-next 08/12] udp: Run inet_lookup bpf program on socket lookup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 28 Aug 2019 09:22:46 +0200
From:   Jakub Sitnicki <jakub@...udflare.com>
To:     bpf@...r.kernel.org, netdev@...r.kernel.org
Cc:     kernel-team@...udflare.com, Lorenz Bauer <lmb@...udflare.com>,
        Marek Majkowski <marek@...udflare.com>
Subject: [RFCv2 bpf-next 08/12] udp: Run inet_lookup bpf program on socket lookup

Following the TCP socket lookup changes, allow selecting the receiving
socket from BPF before searching for bound socket by destination address
and port.

As connected and bound but non-connected socket lookup currently happens in
one step, we split the lookup in two phases to run BPF only after a lookup
for a connected socket was a miss. Hence making sure connected UDP sockets
continue to work as expected in presence of a BPF inet_lookup program.

Suggested-by: Marek Majkowski <marek@...udflare.com>
Reviewed-by: Lorenz Bauer <lmb@...udflare.com>
Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
---
 net/ipv4/udp.c | 44 ++++++++++++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 12 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9fffe9e9eec6..3a4b98f89249 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -353,7 +353,7 @@ int udp_v4_get_port(struct sock *sk, unsigned short snum)
 static int compute_score(struct sock *sk, struct net *net,
 			 __be32 saddr, __be16 sport,
 			 __be32 daddr, unsigned short hnum,
-			 int dif, int sdif)
+			 int dif, int sdif, unsigned char state)
 {
 	int score;
 	struct inet_sock *inet;
@@ -364,6 +364,9 @@ static int compute_score(struct sock *sk, struct net *net,
 	    ipv6_only_sock(sk))
 		return -1;
 
+	if (state && sk->sk_state != state)
+		return -1;
+
 	if (sk->sk_rcv_saddr != daddr)
 		return -1;
 
@@ -411,7 +414,8 @@ static struct sock *udp4_lib_lookup2(struct net *net,
 				     __be32 daddr, unsigned int hnum,
 				     int dif, int sdif,
 				     struct udp_hslot *hslot2,
-				     struct sk_buff *skb)
+				     struct sk_buff *skb,
+				     unsigned char state)
 {
 	struct sock *sk, *result;
 	int score, badness;
@@ -421,7 +425,7 @@ static struct sock *udp4_lib_lookup2(struct net *net,
 	badness = 0;
 	udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
 		score = compute_score(sk, net, saddr, sport,
-				      daddr, hnum, dif, sdif);
+				      daddr, hnum, dif, sdif, state);
 		if (score > badness) {
 			if (sk->sk_reuseport) {
 				hash = udp_ehashfn(net, daddr, hnum,
@@ -454,18 +458,34 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 	slot2 = hash2 & udptable->mask;
 	hslot2 = &udptable->hash2[slot2];
 
+	/* Lookup connected sockets */
 	result = udp4_lib_lookup2(net, saddr, sport,
 				  daddr, hnum, dif, sdif,
-				  hslot2, skb);
-	if (!result) {
-		hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
-		slot2 = hash2 & udptable->mask;
-		hslot2 = &udptable->hash2[slot2];
+				  hslot2, skb, TCP_ESTABLISHED);
+	if (result)
+		goto done;
 
-		result = udp4_lib_lookup2(net, saddr, sport,
-					  htonl(INADDR_ANY), hnum, dif, sdif,
-					  hslot2, skb);
-	}
+	/* Lookup redirect from BPF */
+	result = inet_lookup_run_bpf(net, udptable->protocol,
+				     saddr, sport, daddr, hnum);
+	if (result)
+		goto done;
+
+	/* Lookup bound sockets */
+	result = udp4_lib_lookup2(net, saddr, sport,
+				  daddr, hnum, dif, sdif,
+				  hslot2, skb, 0);
+	if (result)
+		goto done;
+
+	hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
+	slot2 = hash2 & udptable->mask;
+	hslot2 = &udptable->hash2[slot2];
+
+	result = udp4_lib_lookup2(net, saddr, sport,
+				  htonl(INADDR_ANY), hnum, dif, sdif,
+				  hslot2, skb, 0);
+done:
 	if (IS_ERR(result))
 		return NULL;
 	return result;
-- 
2.20.1