selftests_bpf: extend test_tc_tunnel for UDP encap

commit 868d523535 ("bpf: add bpf_skb_adjust_room encap flags")
introduced support to bpf_skb_adjust_room for GSO-friendly GRE
and UDP encapsulation and later introduced associated test_tc_tunnel
tests.  Here those tests are extended to cover UDP encapsulation also.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/config

@@ -25,3 +25,7 @@ CONFIG_XDP_SOCKETS=y
 CONFIG_FTRACE_SYSCALLS=y
 CONFIG_IPV6_TUNNEL=y
 CONFIG_IPV6_GRE=y
+CONFIG_NET_FOU=m
+CONFIG_NET_FOU_IP_TUNNELS=y
+CONFIG_IPV6_FOU=m
+CONFIG_IPV6_FOU_TUNNEL=m

tools/testing/selftests/bpf/progs/test_tc_tunnel.c

@@ -12,6 +12,7 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/tcp.h>
+#include <linux/udp.h>
 #include <linux/pkt_cls.h>
 #include <linux/types.h>
 
@@ -20,16 +21,27 @@
 
 static const int cfg_port = 8000;
 
-struct grev4hdr {
-	struct iphdr ip;
+static const int cfg_udp_src = 20000;
+static const int cfg_udp_dst = 5555;
+
+struct gre_hdr {
 	__be16 flags;
 	__be16 protocol;
 } __attribute__((packed));
 
-struct grev6hdr {
+union l4hdr {
+	struct udphdr udp;
+	struct gre_hdr gre;
+};
+
+struct v4hdr {
+	struct iphdr ip;
+	union l4hdr l4hdr;
+} __attribute__((packed));
+
+struct v6hdr {
 	struct ipv6hdr ip;
-	__be16 flags;
-	__be16 protocol;
+	union l4hdr l4hdr;
 } __attribute__((packed));
 
 static __always_inline void set_ipv4_csum(struct iphdr *iph)
@@ -47,10 +59,10 @@ static __always_inline void set_ipv4_csum(struct iphdr *iph)
 	iph->check = ~((csum & 0xffff) + (csum >> 16));
 }
 
-static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
+static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto)
 {
-	struct grev4hdr h_outer;
 	struct iphdr iph_inner;
+	struct v4hdr h_outer;
 	struct tcphdr tcph;
 	__u64 flags;
 	int olen;
@@ -70,12 +82,29 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
+	olen = sizeof(h_outer.ip);
+
 	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;
-	if (with_gre) {
+	switch (encap_proto) {
+	case IPPROTO_GRE:
 		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
-		olen = sizeof(h_outer);
-	} else {
-		olen = sizeof(h_outer.ip);
+		olen += sizeof(h_outer.l4hdr.gre);
+		h_outer.l4hdr.gre.protocol = bpf_htons(ETH_P_IP);
+		h_outer.l4hdr.gre.flags = 0;
+		break;
+	case IPPROTO_UDP:
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
+		olen += sizeof(h_outer.l4hdr.udp);
+		h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
+		h_outer.l4hdr.udp.dest = __bpf_constant_htons(cfg_udp_dst);
+		h_outer.l4hdr.udp.check = 0;
+		h_outer.l4hdr.udp.len = bpf_htons(bpf_ntohs(iph_inner.tot_len) +
+						  sizeof(h_outer.l4hdr.udp));
+		break;
+	case IPPROTO_IPIP:
+		break;
+	default:
+		return TC_ACT_OK;
 	}
 
 	/* add room between mac and network header */
@@ -85,16 +114,10 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	/* prepare new outer network header */
 	h_outer.ip = iph_inner;
 	h_outer.ip.tot_len = bpf_htons(olen +
-				      bpf_htons(h_outer.ip.tot_len));
-	if (with_gre) {
-		h_outer.ip.protocol = IPPROTO_GRE;
-		h_outer.protocol = bpf_htons(ETH_P_IP);
-		h_outer.flags = 0;
-	} else {
-		h_outer.ip.protocol = IPPROTO_IPIP;
-	}
+				       bpf_ntohs(h_outer.ip.tot_len));
+	h_outer.ip.protocol = encap_proto;
 
-	set_ipv4_csum((void *)&h_outer.ip);
+	set_ipv4_csum(&h_outer.ip);
 
 	/* store new outer network header */
 	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
@@ -104,11 +127,12 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	return TC_ACT_OK;
 }
 
-static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
+static __always_inline int encap_ipv6(struct __sk_buff *skb, __u8 encap_proto)
 {
 	struct ipv6hdr iph_inner;
-	struct grev6hdr h_outer;
+	struct v6hdr h_outer;
 	struct tcphdr tcph;
+	__u16 tot_len;
 	__u64 flags;
 	int olen;
 
@@ -124,14 +148,31 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
-	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
-	if (with_gre) {
-		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
-		olen = sizeof(h_outer);
-	} else {
-		olen = sizeof(h_outer.ip);
-	}
+	olen = sizeof(h_outer.ip);
 
+	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV6;
+	switch (encap_proto) {
+	case IPPROTO_GRE:
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
+		olen += sizeof(h_outer.l4hdr.gre);
+		h_outer.l4hdr.gre.protocol = bpf_htons(ETH_P_IPV6);
+		h_outer.l4hdr.gre.flags = 0;
+		break;
+	case IPPROTO_UDP:
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_UDP;
+		olen += sizeof(h_outer.l4hdr.udp);
+		h_outer.l4hdr.udp.source = __bpf_constant_htons(cfg_udp_src);
+		h_outer.l4hdr.udp.dest = __bpf_constant_htons(cfg_udp_dst);
+		tot_len = bpf_ntohs(iph_inner.payload_len) + sizeof(iph_inner) +
+			  sizeof(h_outer.l4hdr.udp);
+		h_outer.l4hdr.udp.check = 0;
+		h_outer.l4hdr.udp.len = bpf_htons(tot_len);
+		break;
+	case IPPROTO_IPV6:
+		break;
+	default:
+		return TC_ACT_OK;
+	}
 
 	/* add room between mac and network header */
 	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
@@ -141,13 +182,8 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 	h_outer.ip = iph_inner;
 	h_outer.ip.payload_len = bpf_htons(olen +
 					   bpf_ntohs(h_outer.ip.payload_len));
-	if (with_gre) {
-		h_outer.ip.nexthdr = IPPROTO_GRE;
-		h_outer.protocol = bpf_htons(ETH_P_IPV6);
-		h_outer.flags = 0;
-	} else {
-		h_outer.ip.nexthdr = IPPROTO_IPV6;
-	}
+
+	h_outer.ip.nexthdr = encap_proto;
 
 	/* store new outer network header */
 	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
@@ -161,7 +197,7 @@ SEC("encap_ipip")
 int __encap_ipip(struct __sk_buff *skb)
 {
 	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
-		return encap_ipv4(skb, false);
+		return encap_ipv4(skb, IPPROTO_IPIP);
 	else
 		return TC_ACT_OK;
 }
@@ -170,7 +206,16 @@ SEC("encap_gre")
 int __encap_gre(struct __sk_buff *skb)
 {
 	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
-		return encap_ipv4(skb, true);
+		return encap_ipv4(skb, IPPROTO_GRE);
+	else
+		return TC_ACT_OK;
+}
+
+SEC("encap_udp")
+int __encap_udp(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
+		return encap_ipv4(skb, IPPROTO_UDP);
 	else
 		return TC_ACT_OK;
 }
@@ -179,7 +224,7 @@ SEC("encap_ip6tnl")
 int __encap_ip6tnl(struct __sk_buff *skb)
 {
 	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
-		return encap_ipv6(skb, false);
+		return encap_ipv6(skb, IPPROTO_IPV6);
 	else
 		return TC_ACT_OK;
 }
@@ -188,23 +233,34 @@ SEC("encap_ip6gre")
 int __encap_ip6gre(struct __sk_buff *skb)
 {
 	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
-		return encap_ipv6(skb, true);
+		return encap_ipv6(skb, IPPROTO_GRE);
+	else
+		return TC_ACT_OK;
+}
+
+SEC("encap_ip6udp")
+int __encap_ip6udp(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
+		return encap_ipv6(skb, IPPROTO_UDP);
 	else
 		return TC_ACT_OK;
 }
 
 static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
 {
-	char buf[sizeof(struct grev6hdr)];
-	int olen;
+	char buf[sizeof(struct v6hdr)];
+	int olen = len;
 
 	switch (proto) {
 	case IPPROTO_IPIP:
 	case IPPROTO_IPV6:
-		olen = len;
 		break;
 	case IPPROTO_GRE:
-		olen = len + 4 /* gre hdr */;
+		olen += sizeof(struct gre_hdr);
+		break;
+	case IPPROTO_UDP:
+		olen += sizeof(struct udphdr);
 		break;
 	default:
 		return TC_ACT_OK;

tools/testing/selftests/bpf/test_tc_tunnel.sh

@@ -15,6 +15,9 @@ readonly ns2_v4=192.168.1.2
 readonly ns1_v6=fd::1
 readonly ns2_v6=fd::2
 
+# Must match port used by bpf program
+readonly udpport=5555
+
 readonly infile="$(mktemp)"
 readonly outfile="$(mktemp)"
 
@@ -38,8 +41,8 @@ setup() {
 	# clamp route to reserve room for tunnel headers
 	ip -netns "${ns1}" -4 route flush table main
 	ip -netns "${ns1}" -6 route flush table main
-	ip -netns "${ns1}" -4 route add "${ns2_v4}" mtu 1476 dev veth1
-	ip -netns "${ns1}" -6 route add "${ns2_v6}" mtu 1456 dev veth1
+	ip -netns "${ns1}" -4 route add "${ns2_v4}" mtu 1472 dev veth1
+	ip -netns "${ns1}" -6 route add "${ns2_v6}" mtu 1452 dev veth1
 
 	sleep 1
 
@@ -103,6 +106,18 @@ if [[ "$#" -eq "0" ]]; then
 	echo "ip6 gre gso"
 	$0 ipv6 ip6gre 2000
 
+	echo "ip udp"
+	$0 ipv4 udp 100
+
+	echo "ip6 udp"
+	$0 ipv6 ip6udp 100
+
+	echo "ip udp gso"
+	$0 ipv4 udp 2000
+
+	echo "ip6 udp gso"
+	$0 ipv6 ip6udp 2000
+
 	echo "OK. All tests passed"
 	exit 0
 fi
@@ -117,12 +132,20 @@ case "$1" in
 "ipv4")
 	readonly addr1="${ns1_v4}"
 	readonly addr2="${ns2_v4}"
-	readonly netcat_opt=-4
+	readonly ipproto=4
+	readonly netcat_opt=-${ipproto}
+	readonly foumod=fou
+	readonly foutype=ipip
+	readonly fouproto=4
 	;;
 "ipv6")
 	readonly addr1="${ns1_v6}"
 	readonly addr2="${ns2_v6}"
-	readonly netcat_opt=-6
+	readonly ipproto=6
+	readonly netcat_opt=-${ipproto}
+	readonly foumod=fou6
+	readonly foutype=ip6tnl
+	readonly fouproto="41 -6"
 	;;
 *)
 	echo "unknown arg: $1"
@@ -155,11 +178,23 @@ echo "test bpf encap without decap (expect failure)"
 server_listen
 ! client_connect
 
+if [[ "$tuntype" =~ "udp" ]]; then
+	# Set up fou tunnel.
+	ttype="${foutype}"
+	targs="encap fou encap-sport auto encap-dport $udpport"
+	# fou may be a module; allow this to fail.
+	modprobe "${foumod}" ||true
+	ip netns exec "${ns2}" ip fou add port 5555 ipproto ${fouproto}
+else
+	ttype=$tuntype
+	targs=""
+fi
+
 # serverside, insert decap module
 # server is still running
 # client can connect again
-ip netns exec "${ns2}" ip link add dev testtun0 type "${tuntype}" \
-	remote "${addr1}" local "${addr2}"
+ip netns exec "${ns2}" ip link add name testtun0 type "${ttype}" \
+	remote "${addr1}" local "${addr2}" $targs
 # Because packets are decapped by the tunnel they arrive on testtun0 from
 # the IP stack perspective.  Ensure reverse path filtering is disabled
 # otherwise we drop the TCP SYN as arriving on testtun0 instead of the