From 908adce6465394ea4a09c144507a40848e1d7db5 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:48 -0400
Subject: [PATCH 01/13] bpf: in bpf_skb_adjust_room avoid copy in tx fast path

bpf_skb_adjust_room calls skb_cow on grow.

This expensive operation can be avoided in the fast path when the only
other clone has released the header. This is the common case for TCP,
where one headerless clone is kept on the retransmit queue.

It is safe to do so even when touching the gso fields in skb_shinfo.
Regular tunnel encap with iptunnel_handle_offloads takes the same
optimization.

The tcp stack unclones in the unlikely case that it accesses these
fields through headerless clones packets on the retransmit queue (see
__tcp_retransmit_skb).

If any other clones are present, e.g., from packet sockets,
skb_cow_head returns the same value as skb_cow().

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 net/core/filter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index d2511fe46db36..d21e1acdde29a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2971,7 +2971,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff)
 	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
 		return -ENOTSUPP;
 
-	ret = skb_cow(skb, len_diff);
+	ret = skb_cow_head(skb, len_diff);
 	if (unlikely(ret < 0))
 		return ret;
 

From 98cdabcd0798bd9991821493120b928ed0dfab73 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:49 -0400
Subject: [PATCH 02/13] selftests/bpf: bpf tunnel encap test

Validate basic tunnel encapsulation using ipip.

Set up two namespaces connected by veth. Connect a client and server.
Do this with and without bpf encap.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/Makefile          |  3 +-
 .../selftests/bpf/progs/test_tc_tunnel.c      | 83 +++++++++++++++++++
 tools/testing/selftests/bpf/test_tc_tunnel.sh | 75 +++++++++++++++++
 3 files changed, 160 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_tc_tunnel.c
 create mode 100755 tools/testing/selftests/bpf/test_tc_tunnel.sh

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index edd59707cb1f3..cdcc54ddf4b9c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -52,7 +52,8 @@ TEST_PROGS := test_kmod.sh \
 	test_flow_dissector.sh \
 	test_xdp_vlan.sh \
 	test_lwt_ip_encap.sh \
-	test_tcp_check_syncookie.sh
+	test_tcp_check_syncookie.sh \
+	test_tc_tunnel.sh
 
 TEST_PROGS_EXTENDED := with_addr.sh \
 	with_tunnels.sh \
diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
new file mode 100644
index 0000000000000..8223e4347be8f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* In-place tunneling */
+
+#include <linux/stddef.h>
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/pkt_cls.h>
+#include <linux/types.h>
+
+#include "bpf_endian.h"
+#include "bpf_helpers.h"
+
+static const int cfg_port = 8000;
+
+static __always_inline void set_ipv4_csum(struct iphdr *iph)
+{
+	__u16 *iph16 = (__u16 *)iph;
+	__u32 csum;
+	int i;
+
+	iph->check = 0;
+
+#pragma clang loop unroll(full)
+	for (i = 0, csum = 0; i < sizeof(*iph) >> 1; i++)
+		csum += *iph16++;
+
+	iph->check = ~((csum & 0xffff) + (csum >> 16));
+}
+
+SEC("encap")
+int encap_f(struct __sk_buff *skb)
+{
+	struct iphdr iph_outer, iph_inner;
+	struct tcphdr tcph;
+
+	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
+		return TC_ACT_OK;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
+			       sizeof(iph_inner)) < 0)
+		return TC_ACT_OK;
+
+	/* filter only packets we want */
+	if (iph_inner.ihl != 5 || iph_inner.protocol != IPPROTO_TCP)
+		return TC_ACT_OK;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner),
+			       &tcph, sizeof(tcph)) < 0)
+		return TC_ACT_OK;
+
+	if (tcph.dest != __bpf_constant_htons(cfg_port))
+		return TC_ACT_OK;
+
+	/* add room between mac and network header */
+	if (bpf_skb_adjust_room(skb, sizeof(iph_outer), BPF_ADJ_ROOM_NET, 0))
+		return TC_ACT_SHOT;
+
+	/* prepare new outer network header */
+	iph_outer = iph_inner;
+	iph_outer.protocol = IPPROTO_IPIP;
+	iph_outer.tot_len = bpf_htons(sizeof(iph_outer) +
+				      bpf_htons(iph_outer.tot_len));
+	set_ipv4_csum(&iph_outer);
+
+	/* store new outer network header */
+	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_outer, sizeof(iph_outer),
+				BPF_F_INVALIDATE_HASH) < 0)
+		return TC_ACT_SHOT;
+
+	/* bpf_skb_adjust_room has moved header to start of room: restore */
+	if (bpf_skb_store_bytes(skb, ETH_HLEN + sizeof(iph_outer),
+				&iph_inner, sizeof(iph_inner),
+				BPF_F_INVALIDATE_HASH) < 0)
+		return TC_ACT_SHOT;
+
+	return TC_ACT_OK;
+}
+
+char __license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
new file mode 100755
index 0000000000000..6ebb288a3afc7
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -0,0 +1,75 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# In-place tunneling
+
+# must match the port that the bpf program filters on
+readonly port=8000
+
+readonly ns_prefix="ns-$$-"
+readonly ns1="${ns_prefix}1"
+readonly ns2="${ns_prefix}2"
+
+readonly ns1_v4=192.168.1.1
+readonly ns2_v4=192.168.1.2
+
+setup() {
+	ip netns add "${ns1}"
+	ip netns add "${ns2}"
+
+	ip link add dev veth1 mtu 1500 netns "${ns1}" type veth \
+	      peer name veth2 mtu 1500 netns "${ns2}"
+
+	ip -netns "${ns1}" link set veth1 up
+	ip -netns "${ns2}" link set veth2 up
+
+	ip -netns "${ns1}" -4 addr add "${ns1_v4}/24" dev veth1
+	ip -netns "${ns2}" -4 addr add "${ns2_v4}/24" dev veth2
+
+	sleep 1
+}
+
+cleanup() {
+	ip netns del "${ns2}"
+	ip netns del "${ns1}"
+}
+
+server_listen() {
+	ip netns exec "${ns2}" nc -l -p "${port}" &
+	sleep 0.2
+}
+
+client_connect() {
+	ip netns exec "${ns1}" nc -z -w 1 "${ns2_v4}" "${port}"
+	echo $?
+}
+
+set -e
+trap cleanup EXIT
+
+setup
+
+# basic communication works
+echo "test basic connectivity"
+server_listen
+client_connect
+
+# clientside, insert bpf program to encap all TCP to port ${port}
+# client can no longer connect
+ip netns exec "${ns1}" tc qdisc add dev veth1 clsact
+ip netns exec "${ns1}" tc filter add dev veth1 egress \
+	bpf direct-action object-file ./test_tc_tunnel.o section encap
+echo "test bpf encap without decap (expect failure)"
+server_listen
+! client_connect
+
+# serverside, insert decap module
+# server is still running
+# client can connect again
+ip netns exec "${ns2}" ip link add dev testtun0 type ipip \
+	remote "${ns1_v4}" local "${ns2_v4}"
+ip netns exec "${ns2}" ip link set dev testtun0 up
+echo "test bpf encap with tunnel device decap"
+client_connect
+
+echo OK

From ccd34cd3577dd6e244269bb8ccfab228360aa53d Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:50 -0400
Subject: [PATCH 03/13] selftests/bpf: expand bpf tunnel test with decap

The bpf tunnel test encapsulates using bpf, then decapsulates using
a standard tunnel device to verify correctness.

Once encap is verified, also test decap, by replacing the tunnel
device on decap with another bpf program.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 .../selftests/bpf/progs/test_tc_tunnel.c      | 31 +++++++++++++++++++
 tools/testing/selftests/bpf/test_tc_tunnel.sh |  9 ++++++
 2 files changed, 40 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 8223e4347be8f..25db148635ab7 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -80,4 +80,35 @@ int encap_f(struct __sk_buff *skb)
 	return TC_ACT_OK;
 }
 
+SEC("decap")
+int decap_f(struct __sk_buff *skb)
+{
+	struct iphdr iph_outer, iph_inner;
+
+	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
+		return TC_ACT_OK;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
+			       sizeof(iph_outer)) < 0)
+		return TC_ACT_OK;
+
+	if (iph_outer.ihl != 5 || iph_outer.protocol != IPPROTO_IPIP)
+		return TC_ACT_OK;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_outer),
+			       &iph_inner, sizeof(iph_inner)) < 0)
+		return TC_ACT_OK;
+
+	if (bpf_skb_adjust_room(skb, -(int)sizeof(iph_outer),
+				BPF_ADJ_ROOM_NET, 0))
+		return TC_ACT_SHOT;
+
+	/* bpf_skb_adjust_room has moved outer over inner header: restore */
+	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_inner, sizeof(iph_inner),
+				BPF_F_INVALIDATE_HASH) < 0)
+		return TC_ACT_SHOT;
+
+	return TC_ACT_OK;
+}
+
 char __license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 6ebb288a3afc7..91151d91e5a1b 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -72,4 +72,13 @@ ip netns exec "${ns2}" ip link set dev testtun0 up
 echo "test bpf encap with tunnel device decap"
 client_connect
 
+# serverside, use BPF for decap
+ip netns exec "${ns2}" ip link del dev testtun0
+ip netns exec "${ns2}" tc qdisc add dev veth2 clsact
+ip netns exec "${ns2}" tc filter add dev veth2 ingress \
+	bpf direct-action object-file ./test_tc_tunnel.o section decap
+server_listen
+echo "test bpf encap with bpf decap"
+client_connect
+
 echo OK

From ef81bd054942e2bd8289c91a3528e6fc0ca26c1c Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:51 -0400
Subject: [PATCH 04/13] selftests/bpf: expand bpf tunnel test to ipv6

The test only uses ipv4 so far, expand to ipv6.
This is mostly a boilerplate near copy of the ipv4 path.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/config            |   2 +
 .../selftests/bpf/progs/test_tc_tunnel.c      | 116 +++++++++++++++---
 tools/testing/selftests/bpf/test_tc_tunnel.sh |  53 +++++++-
 3 files changed, 149 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index 37f947ec44ed9..a42f4fc4dc11f 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -23,3 +23,5 @@ CONFIG_LWTUNNEL=y
 CONFIG_BPF_STREAM_PARSER=y
 CONFIG_XDP_SOCKETS=y
 CONFIG_FTRACE_SYSCALLS=y
+CONFIG_IPV6_TUNNEL=y
+CONFIG_IPV6_GRE=y
diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 25db148635ab7..591f540ce513d 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -7,6 +7,7 @@
 #include <linux/if_ether.h>
 #include <linux/in.h>
 #include <linux/ip.h>
+#include <linux/ipv6.h>
 #include <linux/tcp.h>
 #include <linux/pkt_cls.h>
 #include <linux/types.h>
@@ -31,15 +32,11 @@ static __always_inline void set_ipv4_csum(struct iphdr *iph)
 	iph->check = ~((csum & 0xffff) + (csum >> 16));
 }
 
-SEC("encap")
-int encap_f(struct __sk_buff *skb)
+static int encap_ipv4(struct __sk_buff *skb)
 {
 	struct iphdr iph_outer, iph_inner;
 	struct tcphdr tcph;
 
-	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
-		return TC_ACT_OK;
-
 	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
 			       sizeof(iph_inner)) < 0)
 		return TC_ACT_OK;
@@ -80,35 +77,118 @@ int encap_f(struct __sk_buff *skb)
 	return TC_ACT_OK;
 }
 
-SEC("decap")
-int decap_f(struct __sk_buff *skb)
+static int encap_ipv6(struct __sk_buff *skb)
 {
-	struct iphdr iph_outer, iph_inner;
+	struct ipv6hdr iph_outer, iph_inner;
+	struct tcphdr tcph;
 
-	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
+			       sizeof(iph_inner)) < 0)
 		return TC_ACT_OK;
 
-	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
-			       sizeof(iph_outer)) < 0)
+	/* filter only packets we want */
+	if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner),
+			       &tcph, sizeof(tcph)) < 0)
 		return TC_ACT_OK;
 
-	if (iph_outer.ihl != 5 || iph_outer.protocol != IPPROTO_IPIP)
+	if (tcph.dest != __bpf_constant_htons(cfg_port))
+		return TC_ACT_OK;
+
+	/* add room between mac and network header */
+	if (bpf_skb_adjust_room(skb, sizeof(iph_outer), BPF_ADJ_ROOM_NET, 0))
+		return TC_ACT_SHOT;
+
+	/* prepare new outer network header */
+	iph_outer = iph_inner;
+	iph_outer.nexthdr = IPPROTO_IPV6;
+	iph_outer.payload_len = bpf_htons(sizeof(iph_outer) +
+					  bpf_ntohs(iph_outer.payload_len));
+
+	/* store new outer network header */
+	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_outer, sizeof(iph_outer),
+				BPF_F_INVALIDATE_HASH) < 0)
+		return TC_ACT_SHOT;
+
+	/* bpf_skb_adjust_room has moved header to start of room: restore */
+	if (bpf_skb_store_bytes(skb, ETH_HLEN + sizeof(iph_outer),
+				&iph_inner, sizeof(iph_inner),
+				BPF_F_INVALIDATE_HASH) < 0)
+		return TC_ACT_SHOT;
+
+	return TC_ACT_OK;
+}
+
+SEC("encap")
+int encap_f(struct __sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __bpf_constant_htons(ETH_P_IP):
+		return encap_ipv4(skb);
+	case __bpf_constant_htons(ETH_P_IPV6):
+		return encap_ipv6(skb);
+	default:
+		/* does not match, ignore */
 		return TC_ACT_OK;
+	}
+}
 
-	if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_outer),
-			       &iph_inner, sizeof(iph_inner)) < 0)
+static int decap_internal(struct __sk_buff *skb, int off, int len)
+{
+	char buf[sizeof(struct ipv6hdr)];
+
+	if (bpf_skb_load_bytes(skb, off + len, &buf, len) < 0)
 		return TC_ACT_OK;
 
-	if (bpf_skb_adjust_room(skb, -(int)sizeof(iph_outer),
-				BPF_ADJ_ROOM_NET, 0))
+	if (bpf_skb_adjust_room(skb, -len, BPF_ADJ_ROOM_NET, 0))
 		return TC_ACT_SHOT;
 
 	/* bpf_skb_adjust_room has moved outer over inner header: restore */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_inner, sizeof(iph_inner),
-				BPF_F_INVALIDATE_HASH) < 0)
+	if (bpf_skb_store_bytes(skb, off, buf, len, BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
 
 	return TC_ACT_OK;
 }
 
+static int decap_ipv4(struct __sk_buff *skb)
+{
+	struct iphdr iph_outer;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
+			       sizeof(iph_outer)) < 0)
+		return TC_ACT_OK;
+
+	if (iph_outer.ihl != 5 || iph_outer.protocol != IPPROTO_IPIP)
+		return TC_ACT_OK;
+
+	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer));
+}
+
+static int decap_ipv6(struct __sk_buff *skb)
+{
+	struct ipv6hdr iph_outer;
+
+	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_outer,
+			       sizeof(iph_outer)) < 0)
+		return TC_ACT_OK;
+
+	if (iph_outer.nexthdr != IPPROTO_IPV6)
+		return TC_ACT_OK;
+
+	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer));
+}
+
+SEC("decap")
+int decap_f(struct __sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __bpf_constant_htons(ETH_P_IP):
+		return decap_ipv4(skb);
+	case __bpf_constant_htons(ETH_P_IPV6):
+		return decap_ipv6(skb);
+	default:
+		/* does not match, ignore */
+		return TC_ACT_OK;
+	}
+}
+
 char __license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 91151d91e5a1b..7b1758f3006b0 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -12,6 +12,9 @@ readonly ns2="${ns_prefix}2"
 
 readonly ns1_v4=192.168.1.1
 readonly ns2_v4=192.168.1.2
+readonly ns1_v6=fd::1
+readonly ns2_v6=fd::2
+
 
 setup() {
 	ip netns add "${ns1}"
@@ -25,6 +28,8 @@ setup() {
 
 	ip -netns "${ns1}" -4 addr add "${ns1_v4}/24" dev veth1
 	ip -netns "${ns2}" -4 addr add "${ns2_v4}/24" dev veth2
+	ip -netns "${ns1}" -6 addr add "${ns1_v6}/64" dev veth1 nodad
+	ip -netns "${ns2}" -6 addr add "${ns2_v6}/64" dev veth2 nodad
 
 	sleep 1
 }
@@ -35,16 +40,56 @@ cleanup() {
 }
 
 server_listen() {
-	ip netns exec "${ns2}" nc -l -p "${port}" &
+	ip netns exec "${ns2}" nc "${netcat_opt}" -l -p "${port}" &
 	sleep 0.2
 }
 
 client_connect() {
-	ip netns exec "${ns1}" nc -z -w 1 "${ns2_v4}" "${port}"
+	ip netns exec "${ns1}" nc "${netcat_opt}" -z -w 1 "${addr2}" "${port}"
 	echo $?
 }
 
 set -e
+
+# no arguments: automated test, run all
+if [[ "$#" -eq "0" ]]; then
+	echo "ipip"
+	$0 ipv4
+
+	echo "ip6ip6"
+	$0 ipv6
+
+	echo "OK. All tests passed"
+	exit 0
+fi
+
+if [[ "$#" -ne "1" ]]; then
+	echo "Usage: $0"
+	echo "   or: $0 <ipv4|ipv6>"
+	exit 1
+fi
+
+case "$1" in
+"ipv4")
+	readonly tuntype=ipip
+	readonly addr1="${ns1_v4}"
+	readonly addr2="${ns2_v4}"
+	readonly netcat_opt=-4
+	;;
+"ipv6")
+	readonly tuntype=ip6tnl
+	readonly addr1="${ns1_v6}"
+	readonly addr2="${ns2_v6}"
+	readonly netcat_opt=-6
+	;;
+*)
+	echo "unknown arg: $1"
+	exit 1
+	;;
+esac
+
+echo "encap ${addr1} to ${addr2}, type ${tuntype}"
+
 trap cleanup EXIT
 
 setup
@@ -66,8 +111,8 @@ server_listen
 # serverside, insert decap module
 # server is still running
 # client can connect again
-ip netns exec "${ns2}" ip link add dev testtun0 type ipip \
-	remote "${ns1_v4}" local "${ns2_v4}"
+ip netns exec "${ns2}" ip link add dev testtun0 type "${tuntype}" \
+	remote "${addr1}" local "${addr2}"
 ip netns exec "${ns2}" ip link set dev testtun0 up
 echo "test bpf encap with tunnel device decap"
 client_connect

From 7255fade7b93e7e84e12f27ae5e8af9cf8b93745 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:52 -0400
Subject: [PATCH 05/13] selftests/bpf: extend bpf tunnel test with gre

GRE is a commonly used protocol. Add GRE cases for both IPv4 and IPv6.

It also inserts different sized headers, which can expose some
unexpected edge cases.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 .../selftests/bpf/progs/test_tc_tunnel.c      | 148 +++++++++++++-----
 tools/testing/selftests/bpf/test_tc_tunnel.sh |  21 ++-
 2 files changed, 123 insertions(+), 46 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 591f540ce513d..900c5653105fe 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -2,6 +2,9 @@
 
 /* In-place tunneling */
 
+#include <stdbool.h>
+#include <string.h>
+
 #include <linux/stddef.h>
 #include <linux/bpf.h>
 #include <linux/if_ether.h>
@@ -17,6 +20,18 @@
 
 static const int cfg_port = 8000;
 
+struct grev4hdr {
+	struct iphdr ip;
+	__be16 flags;
+	__be16 protocol;
+} __attribute__((packed));
+
+struct grev6hdr {
+	struct ipv6hdr ip;
+	__be16 flags;
+	__be16 protocol;
+} __attribute__((packed));
+
 static __always_inline void set_ipv4_csum(struct iphdr *iph)
 {
 	__u16 *iph16 = (__u16 *)iph;
@@ -32,10 +47,12 @@ static __always_inline void set_ipv4_csum(struct iphdr *iph)
 	iph->check = ~((csum & 0xffff) + (csum >> 16));
 }
 
-static int encap_ipv4(struct __sk_buff *skb)
+static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 {
-	struct iphdr iph_outer, iph_inner;
+	struct grev4hdr h_outer;
+	struct iphdr iph_inner;
 	struct tcphdr tcph;
+	int olen;
 
 	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
 			       sizeof(iph_inner)) < 0)
@@ -52,24 +69,33 @@ static int encap_ipv4(struct __sk_buff *skb)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
+	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, sizeof(iph_outer), BPF_ADJ_ROOM_NET, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
-	iph_outer = iph_inner;
-	iph_outer.protocol = IPPROTO_IPIP;
-	iph_outer.tot_len = bpf_htons(sizeof(iph_outer) +
-				      bpf_htons(iph_outer.tot_len));
-	set_ipv4_csum(&iph_outer);
+	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;
+	}
+
+	set_ipv4_csum((void *)&h_outer.ip);
 
 	/* store new outer network header */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_outer, sizeof(iph_outer),
+	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
 
 	/* bpf_skb_adjust_room has moved header to start of room: restore */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN + sizeof(iph_outer),
+	if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
 				&iph_inner, sizeof(iph_inner),
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
@@ -77,10 +103,12 @@ static int encap_ipv4(struct __sk_buff *skb)
 	return TC_ACT_OK;
 }
 
-static int encap_ipv6(struct __sk_buff *skb)
+static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 {
-	struct ipv6hdr iph_outer, iph_inner;
+	struct ipv6hdr iph_inner;
+	struct grev6hdr h_outer;
 	struct tcphdr tcph;
+	int olen;
 
 	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
 			       sizeof(iph_inner)) < 0)
@@ -94,23 +122,31 @@ static int encap_ipv6(struct __sk_buff *skb)
 	if (tcph.dest != __bpf_constant_htons(cfg_port))
 		return TC_ACT_OK;
 
+	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, sizeof(iph_outer), BPF_ADJ_ROOM_NET, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
-	iph_outer = iph_inner;
-	iph_outer.nexthdr = IPPROTO_IPV6;
-	iph_outer.payload_len = bpf_htons(sizeof(iph_outer) +
-					  bpf_ntohs(iph_outer.payload_len));
+	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;
+	}
 
 	/* store new outer network header */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_outer, sizeof(iph_outer),
+	if (bpf_skb_store_bytes(skb, ETH_HLEN, &h_outer, olen,
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
 
 	/* bpf_skb_adjust_room has moved header to start of room: restore */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN + sizeof(iph_outer),
+	if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
 				&iph_inner, sizeof(iph_inner),
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
@@ -118,28 +154,63 @@ static int encap_ipv6(struct __sk_buff *skb)
 	return TC_ACT_OK;
 }
 
-SEC("encap")
-int encap_f(struct __sk_buff *skb)
+SEC("encap_ipip")
+int __encap_ipip(struct __sk_buff *skb)
 {
-	switch (skb->protocol) {
-	case __bpf_constant_htons(ETH_P_IP):
-		return encap_ipv4(skb);
-	case __bpf_constant_htons(ETH_P_IPV6):
-		return encap_ipv6(skb);
-	default:
-		/* does not match, ignore */
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
+		return encap_ipv4(skb, false);
+	else
 		return TC_ACT_OK;
-	}
 }
 
-static int decap_internal(struct __sk_buff *skb, int off, int len)
+SEC("encap_gre")
+int __encap_gre(struct __sk_buff *skb)
 {
-	char buf[sizeof(struct ipv6hdr)];
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
+		return encap_ipv4(skb, true);
+	else
+		return TC_ACT_OK;
+}
 
-	if (bpf_skb_load_bytes(skb, off + len, &buf, len) < 0)
+SEC("encap_ip6tnl")
+int __encap_ip6tnl(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
+		return encap_ipv6(skb, false);
+	else
+		return TC_ACT_OK;
+}
+
+SEC("encap_ip6gre")
+int __encap_ip6gre(struct __sk_buff *skb)
+{
+	if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6))
+		return encap_ipv6(skb, true);
+	else
 		return TC_ACT_OK;
+}
 
-	if (bpf_skb_adjust_room(skb, -len, BPF_ADJ_ROOM_NET, 0))
+static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
+{
+	char buf[sizeof(struct grev6hdr)];
+	int olen;
+
+	switch (proto) {
+	case IPPROTO_IPIP:
+	case IPPROTO_IPV6:
+		olen = len;
+		break;
+	case IPPROTO_GRE:
+		olen = len + 4 /* gre hdr */;
+		break;
+	default:
+		return TC_ACT_OK;
+	}
+
+	if (bpf_skb_load_bytes(skb, off + olen, &buf, olen) < 0)
+		return TC_ACT_OK;
+
+	if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_NET, 0))
 		return TC_ACT_SHOT;
 
 	/* bpf_skb_adjust_room has moved outer over inner header: restore */
@@ -157,10 +228,11 @@ static int decap_ipv4(struct __sk_buff *skb)
 			       sizeof(iph_outer)) < 0)
 		return TC_ACT_OK;
 
-	if (iph_outer.ihl != 5 || iph_outer.protocol != IPPROTO_IPIP)
+	if (iph_outer.ihl != 5)
 		return TC_ACT_OK;
 
-	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer));
+	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
+			      iph_outer.protocol);
 }
 
 static int decap_ipv6(struct __sk_buff *skb)
@@ -171,10 +243,8 @@ static int decap_ipv6(struct __sk_buff *skb)
 			       sizeof(iph_outer)) < 0)
 		return TC_ACT_OK;
 
-	if (iph_outer.nexthdr != IPPROTO_IPV6)
-		return TC_ACT_OK;
-
-	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer));
+	return decap_internal(skb, ETH_HLEN, sizeof(iph_outer),
+			      iph_outer.nexthdr);
 }
 
 SEC("decap")
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 7b1758f3006b0..c78922048610b 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -54,30 +54,36 @@ set -e
 # no arguments: automated test, run all
 if [[ "$#" -eq "0" ]]; then
 	echo "ipip"
-	$0 ipv4
+	$0 ipv4 ipip
 
 	echo "ip6ip6"
-	$0 ipv6
+	$0 ipv6 ip6tnl
+
+	echo "ip gre"
+	$0 ipv4 gre
+
+	echo "ip6 gre"
+	$0 ipv6 ip6gre
 
 	echo "OK. All tests passed"
 	exit 0
 fi
 
-if [[ "$#" -ne "1" ]]; then
+if [[ "$#" -ne "2" ]]; then
 	echo "Usage: $0"
-	echo "   or: $0 <ipv4|ipv6>"
+	echo "   or: $0 <ipv4|ipv6> <tuntype>"
 	exit 1
 fi
 
 case "$1" in
 "ipv4")
-	readonly tuntype=ipip
+	readonly tuntype=$2
 	readonly addr1="${ns1_v4}"
 	readonly addr2="${ns2_v4}"
 	readonly netcat_opt=-4
 	;;
 "ipv6")
-	readonly tuntype=ip6tnl
+	readonly tuntype=$2
 	readonly addr1="${ns1_v6}"
 	readonly addr2="${ns2_v6}"
 	readonly netcat_opt=-6
@@ -103,7 +109,8 @@ client_connect
 # client can no longer connect
 ip netns exec "${ns1}" tc qdisc add dev veth1 clsact
 ip netns exec "${ns1}" tc filter add dev veth1 egress \
-	bpf direct-action object-file ./test_tc_tunnel.o section encap
+	bpf direct-action object-file ./test_tc_tunnel.o \
+	section "encap_${tuntype}"
 echo "test bpf encap without decap (expect failure)"
 server_listen
 ! client_connect

From 8142958954d17a31e0ac9e3a9c91103a1c171179 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:53 -0400
Subject: [PATCH 06/13] selftests/bpf: extend bpf tunnel test with tso

Segmentation offload takes a longer path. Verify that the feature
works with large packets.

The test succeeds if not setting dodgy in bpf_skb_adjust_room, as veth
TSO is permissive.

If not setting SKB_GSO_DODGY, this enables tunneled TSO offload on
supporting NICs.

The feature sets SKB_GSO_DODGY because the caller is untrusted. As a
result the packets traverse through the gso stack at least up to TCP.
And fail the gso_type validation, such as the skb->encapsulation check
in gre_gso_segment and the gso_type checks introduced in commit
418e897e0716 ("gso: validate gso_type on ipip style tunnel").

This will be addressed in a follow-on feature patch. In the meantime,
disable the new gso tests.

Changes v1->v2:
  - not all netcat versions support flag '-q', use timeout instead

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/test_tc_tunnel.sh | 60 +++++++++++++++----
 1 file changed, 49 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index c78922048610b..9e18754f23547 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -15,6 +15,8 @@ readonly ns2_v4=192.168.1.2
 readonly ns1_v6=fd::1
 readonly ns2_v6=fd::2
 
+readonly infile="$(mktemp)"
+readonly outfile="$(mktemp)"
 
 setup() {
 	ip netns add "${ns1}"
@@ -23,6 +25,8 @@ setup() {
 	ip link add dev veth1 mtu 1500 netns "${ns1}" type veth \
 	      peer name veth2 mtu 1500 netns "${ns2}"
 
+	ip netns exec "${ns1}" ethtool -K veth1 tso off
+
 	ip -netns "${ns1}" link set veth1 up
 	ip -netns "${ns2}" link set veth2 up
 
@@ -32,58 +36,86 @@ setup() {
 	ip -netns "${ns2}" -6 addr add "${ns2_v6}/64" dev veth2 nodad
 
 	sleep 1
+
+	dd if=/dev/urandom of="${infile}" bs="${datalen}" count=1 status=none
 }
 
 cleanup() {
 	ip netns del "${ns2}"
 	ip netns del "${ns1}"
+
+	if [[ -f "${outfile}" ]]; then
+		rm "${outfile}"
+	fi
+	if [[ -f "${infile}" ]]; then
+		rm "${infile}"
+	fi
 }
 
 server_listen() {
-	ip netns exec "${ns2}" nc "${netcat_opt}" -l -p "${port}" &
+	ip netns exec "${ns2}" nc "${netcat_opt}" -l -p "${port}" > "${outfile}" &
+	server_pid=$!
 	sleep 0.2
 }
 
 client_connect() {
-	ip netns exec "${ns1}" nc "${netcat_opt}" -z -w 1 "${addr2}" "${port}"
+	ip netns exec "${ns1}" timeout 2 nc "${netcat_opt}" -w 1 "${addr2}" "${port}" < "${infile}"
 	echo $?
 }
 
+verify_data() {
+	wait "${server_pid}"
+	# sha1sum returns two fields [sha1] [filepath]
+	# convert to bash array and access first elem
+	insum=($(sha1sum ${infile}))
+	outsum=($(sha1sum ${outfile}))
+	if [[ "${insum[0]}" != "${outsum[0]}" ]]; then
+		echo "data mismatch"
+		exit 1
+	fi
+}
+
 set -e
 
 # no arguments: automated test, run all
 if [[ "$#" -eq "0" ]]; then
 	echo "ipip"
-	$0 ipv4 ipip
+	$0 ipv4 ipip 100
 
 	echo "ip6ip6"
-	$0 ipv6 ip6tnl
+	$0 ipv6 ip6tnl 100
 
 	echo "ip gre"
-	$0 ipv4 gre
+	$0 ipv4 gre 100
 
 	echo "ip6 gre"
-	$0 ipv6 ip6gre
+	$0 ipv6 ip6gre 100
+
+	# disabled until passes SKB_GSO_DODGY checks
+	# echo "ip gre gso"
+	# $0 ipv4 gre 2000
+
+	# disabled until passes SKB_GSO_DODGY checks
+	# echo "ip6 gre gso"
+	# $0 ipv6 ip6gre 2000
 
 	echo "OK. All tests passed"
 	exit 0
 fi
 
-if [[ "$#" -ne "2" ]]; then
+if [[ "$#" -ne "3" ]]; then
 	echo "Usage: $0"
-	echo "   or: $0 <ipv4|ipv6> <tuntype>"
+	echo "   or: $0 <ipv4|ipv6> <tuntype> <data_len>"
 	exit 1
 fi
 
 case "$1" in
 "ipv4")
-	readonly tuntype=$2
 	readonly addr1="${ns1_v4}"
 	readonly addr2="${ns2_v4}"
 	readonly netcat_opt=-4
 	;;
 "ipv6")
-	readonly tuntype=$2
 	readonly addr1="${ns1_v6}"
 	readonly addr2="${ns2_v6}"
 	readonly netcat_opt=-6
@@ -94,7 +126,10 @@ case "$1" in
 	;;
 esac
 
-echo "encap ${addr1} to ${addr2}, type ${tuntype}"
+readonly tuntype=$2
+readonly datalen=$3
+
+echo "encap ${addr1} to ${addr2}, type ${tuntype}, len ${datalen}"
 
 trap cleanup EXIT
 
@@ -104,6 +139,7 @@ setup
 echo "test basic connectivity"
 server_listen
 client_connect
+verify_data
 
 # clientside, insert bpf program to encap all TCP to port ${port}
 # client can no longer connect
@@ -123,6 +159,7 @@ ip netns exec "${ns2}" ip link add dev testtun0 type "${tuntype}" \
 ip netns exec "${ns2}" ip link set dev testtun0 up
 echo "test bpf encap with tunnel device decap"
 client_connect
+verify_data
 
 # serverside, use BPF for decap
 ip netns exec "${ns2}" ip link del dev testtun0
@@ -132,5 +169,6 @@ ip netns exec "${ns2}" tc filter add dev veth2 ingress \
 server_listen
 echo "test bpf encap with bpf decap"
 client_connect
+verify_data
 
 echo OK

From 14aa31929b724b70fb63a9b0e7877da325b25cfe Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:54 -0400
Subject: [PATCH 07/13] bpf: add bpf_skb_adjust_room mode BPF_ADJ_ROOM_MAC

bpf_skb_adjust_room net allows inserting room in an skb.

Existing mode BPF_ADJ_ROOM_NET inserts room after the network header
by pulling the skb, moving the network header forward and zeroing the
new space.

Add new mode BPF_ADJUST_ROOM_MAC that inserts room after the mac
header. This allows inserting tunnel headers in front of the network
header without having to recreate the network header in the original
space, avoiding two copies.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/uapi/linux/bpf.h |  6 +++++-
 net/core/filter.c        | 38 ++++++++++++++++++++------------------
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3c04410137d95..7c8fd0647070a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1478,7 +1478,10 @@ union bpf_attr {
  * 		Grow or shrink the room for data in the packet associated to
  * 		*skb* by *len_diff*, and according to the selected *mode*.
  *
- * 		There is a single supported mode at this time:
+ *		There are two supported modes at this time:
+ *
+ *		* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ *		  (room space is added or removed below the layer 2 header).
  *
  * 		* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
  * 		  (room space is added or removed below the layer 3 header).
@@ -2627,6 +2630,7 @@ enum bpf_func_id {
 /* Mode for BPF_FUNC_skb_adjust_room helper. */
 enum bpf_adj_room_mode {
 	BPF_ADJ_ROOM_NET,
+	BPF_ADJ_ROOM_MAC,
 };
 
 /* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
diff --git a/net/core/filter.c b/net/core/filter.c
index d21e1acdde29a..e7b7720b18e94 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2963,9 +2963,8 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
 	}
 }
 
-static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff)
+static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
 {
-	u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
 	int ret;
 
 	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
@@ -2992,9 +2991,8 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff)
 	return 0;
 }
 
-static int bpf_skb_net_shrink(struct sk_buff *skb, u32 len_diff)
+static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
 {
-	u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
 	int ret;
 
 	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
@@ -3027,7 +3025,8 @@ static u32 __bpf_skb_max_len(const struct sk_buff *skb)
 			  SKB_MAX_ALLOC;
 }
 
-static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)
+BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
+	   u32, mode, u64, flags)
 {
 	bool trans_same = skb->transport_header == skb->network_header;
 	u32 len_cur, len_diff_abs = abs(len_diff);
@@ -3035,14 +3034,28 @@ static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)
 	u32 len_max = __bpf_skb_max_len(skb);
 	__be16 proto = skb->protocol;
 	bool shrink = len_diff < 0;
+	u32 off;
 	int ret;
 
+	if (unlikely(flags))
+		return -EINVAL;
 	if (unlikely(len_diff_abs > 0xfffU))
 		return -EFAULT;
 	if (unlikely(proto != htons(ETH_P_IP) &&
 		     proto != htons(ETH_P_IPV6)))
 		return -ENOTSUPP;
 
+	off = skb_mac_header_len(skb);
+	switch (mode) {
+	case BPF_ADJ_ROOM_NET:
+		off += bpf_skb_net_base_len(skb);
+		break;
+	case BPF_ADJ_ROOM_MAC:
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
 	len_cur = skb->len - skb_network_offset(skb);
 	if (skb_transport_header_was_set(skb) && !trans_same)
 		len_cur = skb_network_header_len(skb);
@@ -3052,24 +3065,13 @@ static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)
 			 !skb_is_gso(skb))))
 		return -ENOTSUPP;
 
-	ret = shrink ? bpf_skb_net_shrink(skb, len_diff_abs) :
-		       bpf_skb_net_grow(skb, len_diff_abs);
+	ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs) :
+		       bpf_skb_net_grow(skb, off, len_diff_abs);
 
 	bpf_compute_data_pointers(skb);
 	return ret;
 }
 
-BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
-	   u32, mode, u64, flags)
-{
-	if (unlikely(flags))
-		return -EINVAL;
-	if (likely(mode == BPF_ADJ_ROOM_NET))
-		return bpf_skb_adjust_net(skb, len_diff);
-
-	return -ENOTSUPP;
-}
-
 static const struct bpf_func_proto bpf_skb_adjust_room_proto = {
 	.func		= bpf_skb_adjust_room,
 	.gpl_only	= false,

From 2278f6cc151a8bef6ba0b3fe3009d14dc3c51c4a Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:55 -0400
Subject: [PATCH 08/13] bpf: add bpf_skb_adjust_room flag
 BPF_F_ADJ_ROOM_FIXED_GSO

bpf_skb_adjust_room adjusts gso_size of gso packets to account for the
pushed or popped header room.

This is not allowed with UDP, where gso_size delineates datagrams. Add
an option to avoid these updates and allow this call for datagrams.

It can also be used with TCP, when MSS is known to allow headroom,
e.g., through MSS clamping or route MTU.

Changes v1->v2:
  - document flag BPF_F_ADJ_ROOM_FIXED_GSO
  - do not expose BPF_F_ADJ_ROOM_MASK through uapi, as it may change.

Link: https://patchwork.ozlabs.org/patch/1052497/
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/uapi/linux/bpf.h |  9 +++++++--
 net/core/filter.c        | 38 +++++++++++++++++++++++++++-----------
 2 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 7c8fd0647070a..4f157d0ec5714 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1486,8 +1486,10 @@ union bpf_attr {
  * 		* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
  * 		  (room space is added or removed below the layer 3 header).
  *
- * 		All values for *flags* are reserved for future usage, and must
- * 		be left at zero.
+ *		There is one supported flag at this time:
+ *
+ *		* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
+ *		  Adjusting mss in this way is not allowed for datagrams.
  *
  * 		A call to this helper is susceptible to change the underlaying
  * 		packet buffer. Therefore, at load time, all checks on pointers
@@ -2627,6 +2629,9 @@ enum bpf_func_id {
 /* Current network namespace */
 #define BPF_F_CURRENT_NETNS		(-1L)
 
+/* BPF_FUNC_skb_adjust_room flags. */
+#define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)
+
 /* Mode for BPF_FUNC_skb_adjust_room helper. */
 enum bpf_adj_room_mode {
 	BPF_ADJ_ROOM_NET,
diff --git a/net/core/filter.c b/net/core/filter.c
index e7b7720b18e94..d3240a0a0eeb3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2963,12 +2963,19 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
 	}
 }
 
-static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
+#define BPF_F_ADJ_ROOM_MASK		(BPF_F_ADJ_ROOM_FIXED_GSO)
+
+static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
+			    u64 flags)
 {
 	int ret;
 
-	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
-		return -ENOTSUPP;
+	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
+		/* udp gso_size delineates datagrams, only allow if fixed */
+		if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) ||
+		    !(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+			return -ENOTSUPP;
+	}
 
 	ret = skb_cow_head(skb, len_diff);
 	if (unlikely(ret < 0))
@@ -2982,7 +2989,9 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
 		/* Due to header grow, MSS needs to be downgraded. */
-		skb_decrease_gso_size(shinfo, len_diff);
+		if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+			skb_decrease_gso_size(shinfo, len_diff);
+
 		/* Header must be checked, and gso_segs recomputed. */
 		shinfo->gso_type |= SKB_GSO_DODGY;
 		shinfo->gso_segs = 0;
@@ -2991,12 +3000,17 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff)
 	return 0;
 }
 
-static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
+static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff,
+			      u64 flags)
 {
 	int ret;
 
-	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb))
-		return -ENOTSUPP;
+	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
+		/* udp gso_size delineates datagrams, only allow if fixed */
+		if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) ||
+		    !(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+			return -ENOTSUPP;
+	}
 
 	ret = skb_unclone(skb, GFP_ATOMIC);
 	if (unlikely(ret < 0))
@@ -3010,7 +3024,9 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff)
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
 		/* Due to header shrink, MSS can be upgraded. */
-		skb_increase_gso_size(shinfo, len_diff);
+		if (!(flags & BPF_F_ADJ_ROOM_FIXED_GSO))
+			skb_increase_gso_size(shinfo, len_diff);
+
 		/* Header must be checked, and gso_segs recomputed. */
 		shinfo->gso_type |= SKB_GSO_DODGY;
 		shinfo->gso_segs = 0;
@@ -3037,7 +3053,7 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
 	u32 off;
 	int ret;
 
-	if (unlikely(flags))
+	if (unlikely(flags & ~BPF_F_ADJ_ROOM_MASK))
 		return -EINVAL;
 	if (unlikely(len_diff_abs > 0xfffU))
 		return -EFAULT;
@@ -3065,8 +3081,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
 			 !skb_is_gso(skb))))
 		return -ENOTSUPP;
 
-	ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs) :
-		       bpf_skb_net_grow(skb, off, len_diff_abs);
+	ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs, flags) :
+		       bpf_skb_net_grow(skb, off, len_diff_abs, flags);
 
 	bpf_compute_data_pointers(skb);
 	return ret;

From 868d523535c2d00b696753ece606e641a816e91e Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:56 -0400
Subject: [PATCH 09/13] bpf: add bpf_skb_adjust_room encap flags

When pushing tunnel headers, annotate skbs in the same way as tunnel
devices.

For GSO packets, the network stack requires certain fields set to
segment packets with tunnel headers. gro_gse_segment depends on
transport and inner mac header, for instance.

Add an option to pass this information.

Remove the restriction on len_diff to network header length, which
is too short, e.g., for GRE protocols.

Changes
  v1->v2:
  - document new flags
  - BPF_F_ADJ_ROOM_MASK moved
  v2->v3:
  - BPF_F_ADJ_ROOM_ENCAP_L3_MASK moved

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 include/uapi/linux/bpf.h | 16 +++++++++-
 net/core/filter.c        | 66 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 76 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4f157d0ec5714..837024512bafd 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1486,11 +1486,20 @@ union bpf_attr {
  * 		* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
  * 		  (room space is added or removed below the layer 3 header).
  *
- *		There is one supported flag at this time:
+ *		The following flags are supported at this time:
  *
  *		* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
  *		  Adjusting mss in this way is not allowed for datagrams.
  *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4 **:
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6 **:
+ *		  Any new space is reserved to hold a tunnel header.
+ *		  Configure skb offsets and other fields accordingly.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L4_GRE **:
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L4_UDP **:
+ *		  Use with ENCAP_L3 flags to further specify the tunnel type.
+ *
  * 		A call to this helper is susceptible to change the underlaying
  * 		packet buffer. Therefore, at load time, all checks on pointers
  * 		previously done by the verifier are invalidated and must be
@@ -2632,6 +2641,11 @@ enum bpf_func_id {
 /* BPF_FUNC_skb_adjust_room flags. */
 #define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)
 
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	(1ULL << 1)
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	(1ULL << 2)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE	(1ULL << 3)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP	(1ULL << 4)
+
 /* Mode for BPF_FUNC_skb_adjust_room helper. */
 enum bpf_adj_room_mode {
 	BPF_ADJ_ROOM_NET,
diff --git a/net/core/filter.c b/net/core/filter.c
index d3240a0a0eeb3..c1d19b074d6c4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2963,11 +2963,20 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb)
 	}
 }
 
-#define BPF_F_ADJ_ROOM_MASK		(BPF_F_ADJ_ROOM_FIXED_GSO)
+#define BPF_F_ADJ_ROOM_ENCAP_L3_MASK	(BPF_F_ADJ_ROOM_ENCAP_L3_IPV4 | \
+					 BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)
+
+#define BPF_F_ADJ_ROOM_MASK		(BPF_F_ADJ_ROOM_FIXED_GSO | \
+					 BPF_F_ADJ_ROOM_ENCAP_L3_MASK | \
+					 BPF_F_ADJ_ROOM_ENCAP_L4_GRE | \
+					 BPF_F_ADJ_ROOM_ENCAP_L4_UDP)
 
 static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 			    u64 flags)
 {
+	bool encap = flags & BPF_F_ADJ_ROOM_ENCAP_L3_MASK;
+	unsigned int gso_type = SKB_GSO_DODGY;
+	u16 mac_len, inner_net, inner_trans;
 	int ret;
 
 	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
@@ -2981,10 +2990,60 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 	if (unlikely(ret < 0))
 		return ret;
 
+	if (encap) {
+		if (skb->protocol != htons(ETH_P_IP) &&
+		    skb->protocol != htons(ETH_P_IPV6))
+			return -ENOTSUPP;
+
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV4 &&
+		    flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)
+			return -EINVAL;
+
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L4_GRE &&
+		    flags & BPF_F_ADJ_ROOM_ENCAP_L4_UDP)
+			return -EINVAL;
+
+		if (skb->encapsulation)
+			return -EALREADY;
+
+		mac_len = skb->network_header - skb->mac_header;
+		inner_net = skb->network_header;
+		inner_trans = skb->transport_header;
+	}
+
 	ret = bpf_skb_net_hdr_push(skb, off, len_diff);
 	if (unlikely(ret < 0))
 		return ret;
 
+	if (encap) {
+		/* inner mac == inner_net on l3 encap */
+		skb->inner_mac_header = inner_net;
+		skb->inner_network_header = inner_net;
+		skb->inner_transport_header = inner_trans;
+		skb_set_inner_protocol(skb, skb->protocol);
+
+		skb->encapsulation = 1;
+		skb_set_network_header(skb, mac_len);
+
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L4_UDP)
+			gso_type |= SKB_GSO_UDP_TUNNEL;
+		else if (flags & BPF_F_ADJ_ROOM_ENCAP_L4_GRE)
+			gso_type |= SKB_GSO_GRE;
+		else if (flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)
+			gso_type |= SKB_GSO_IPXIP6;
+		else
+			gso_type |= SKB_GSO_IPXIP4;
+
+		if (flags & BPF_F_ADJ_ROOM_ENCAP_L4_GRE ||
+		    flags & BPF_F_ADJ_ROOM_ENCAP_L4_UDP) {
+			int nh_len = flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV6 ?
+					sizeof(struct ipv6hdr) :
+					sizeof(struct iphdr);
+
+			skb_set_transport_header(skb, mac_len + nh_len);
+		}
+	}
+
 	if (skb_is_gso(skb)) {
 		struct skb_shared_info *shinfo = skb_shinfo(skb);
 
@@ -2993,7 +3052,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 			skb_decrease_gso_size(shinfo, len_diff);
 
 		/* Header must be checked, and gso_segs recomputed. */
-		shinfo->gso_type |= SKB_GSO_DODGY;
+		shinfo->gso_type |= gso_type;
 		shinfo->gso_segs = 0;
 	}
 
@@ -3044,7 +3103,6 @@ static u32 __bpf_skb_max_len(const struct sk_buff *skb)
 BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
 	   u32, mode, u64, flags)
 {
-	bool trans_same = skb->transport_header == skb->network_header;
 	u32 len_cur, len_diff_abs = abs(len_diff);
 	u32 len_min = bpf_skb_net_base_len(skb);
 	u32 len_max = __bpf_skb_max_len(skb);
@@ -3073,8 +3131,6 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
 	}
 
 	len_cur = skb->len - skb_network_offset(skb);
-	if (skb_transport_header_was_set(skb) && !trans_same)
-		len_cur = skb_network_header_len(skb);
 	if ((shrink && (len_diff_abs >= len_cur ||
 			len_cur - len_diff_abs < len_min)) ||
 	    (!shrink && (skb->len + len_diff_abs > len_max &&

From 6c408decbdc8a12a12a93c4d763cbc2a264f9332 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:57 -0400
Subject: [PATCH 10/13] bpf: Sync bpf.h to tools

Sync include/uapi/linux/bpf.h with tools/

Changes
  v1->v2:
  - BPF_F_ADJ_ROOM_MASK moved, no longer in this commit
  v2->v3:
  - BPF_F_ADJ_ROOM_ENCAP_L3_MASK moved, no longer in this commit

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/include/uapi/linux/bpf.h | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 3c04410137d95..837024512bafd 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1478,13 +1478,27 @@ union bpf_attr {
  * 		Grow or shrink the room for data in the packet associated to
  * 		*skb* by *len_diff*, and according to the selected *mode*.
  *
- * 		There is a single supported mode at this time:
+ *		There are two supported modes at this time:
+ *
+ *		* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ *		  (room space is added or removed below the layer 2 header).
  *
  * 		* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
  * 		  (room space is added or removed below the layer 3 header).
  *
- * 		All values for *flags* are reserved for future usage, and must
- * 		be left at zero.
+ *		The following flags are supported at this time:
+ *
+ *		* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
+ *		  Adjusting mss in this way is not allowed for datagrams.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4 **:
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6 **:
+ *		  Any new space is reserved to hold a tunnel header.
+ *		  Configure skb offsets and other fields accordingly.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L4_GRE **:
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L4_UDP **:
+ *		  Use with ENCAP_L3 flags to further specify the tunnel type.
  *
  * 		A call to this helper is susceptible to change the underlaying
  * 		packet buffer. Therefore, at load time, all checks on pointers
@@ -2624,9 +2638,18 @@ enum bpf_func_id {
 /* Current network namespace */
 #define BPF_F_CURRENT_NETNS		(-1L)
 
+/* BPF_FUNC_skb_adjust_room flags. */
+#define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)
+
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	(1ULL << 1)
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	(1ULL << 2)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE	(1ULL << 3)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP	(1ULL << 4)
+
 /* Mode for BPF_FUNC_skb_adjust_room helper. */
 enum bpf_adj_room_mode {
 	BPF_ADJ_ROOM_NET,
+	BPF_ADJ_ROOM_MAC,
 };
 
 /* Mode for BPF_FUNC_skb_load_bytes_relative helper. */

From 005edd16562b78f416e2f576a64789c90d96882f Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:58 -0400
Subject: [PATCH 11/13] selftests/bpf: convert bpf tunnel test to
 BPF_ADJ_ROOM_MAC

Avoid moving the network layer header when prefixing tunnel headers.

This avoids an explicit call to bpf_skb_store_bytes and an implicit
move of the network header bytes in bpf_skb_adjust_room.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 .../selftests/bpf/progs/test_tc_tunnel.c      | 25 +++----------------
 1 file changed, 3 insertions(+), 22 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 900c5653105fe..f6a16fd23dbd5 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -72,7 +72,7 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
@@ -94,12 +94,6 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
 
-	/* bpf_skb_adjust_room has moved header to start of room: restore */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
-				&iph_inner, sizeof(iph_inner),
-				BPF_F_INVALIDATE_HASH) < 0)
-		return TC_ACT_SHOT;
-
 	return TC_ACT_OK;
 }
 
@@ -125,7 +119,7 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
@@ -145,12 +139,6 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 				BPF_F_INVALIDATE_HASH) < 0)
 		return TC_ACT_SHOT;
 
-	/* bpf_skb_adjust_room has moved header to start of room: restore */
-	if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
-				&iph_inner, sizeof(iph_inner),
-				BPF_F_INVALIDATE_HASH) < 0)
-		return TC_ACT_SHOT;
-
 	return TC_ACT_OK;
 }
 
@@ -207,14 +195,7 @@ static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
 		return TC_ACT_OK;
 	}
 
-	if (bpf_skb_load_bytes(skb, off + olen, &buf, olen) < 0)
-		return TC_ACT_OK;
-
-	if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_NET, 0))
-		return TC_ACT_SHOT;
-
-	/* bpf_skb_adjust_room has moved outer over inner header: restore */
-	if (bpf_skb_store_bytes(skb, off, buf, len, BPF_F_INVALIDATE_HASH) < 0)
+	if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC, 0))
 		return TC_ACT_SHOT;
 
 	return TC_ACT_OK;

From 94f16813e1b297d31f8fe6217cd9be19e080f998 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:32:59 -0400
Subject: [PATCH 12/13] selftests/bpf: convert bpf tunnel test to
 BPF_F_ADJ_ROOM_FIXED_GSO

Lower route MTU to ensure packets fit in device MTU after encap, then
skip the gso_size changes.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 11 ++++++++---
 tools/testing/selftests/bpf/test_tc_tunnel.sh      |  6 ++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index f6a16fd23dbd5..3b79dffb81037 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -52,6 +52,7 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
 	struct grev4hdr h_outer;
 	struct iphdr iph_inner;
 	struct tcphdr tcph;
+	__u64 flags;
 	int olen;
 
 	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
@@ -69,10 +70,11 @@ 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;
 
+	flags = BPF_F_ADJ_ROOM_FIXED_GSO;
 	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
@@ -102,6 +104,7 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
 	struct ipv6hdr iph_inner;
 	struct grev6hdr h_outer;
 	struct tcphdr tcph;
+	__u64 flags;
 	int olen;
 
 	if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
@@ -116,10 +119,11 @@ 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;
 	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
 	/* add room between mac and network header */
-	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
+	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
 		return TC_ACT_SHOT;
 
 	/* prepare new outer network header */
@@ -195,7 +199,8 @@ static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
 		return TC_ACT_OK;
 	}
 
-	if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC, 0))
+	if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC,
+				BPF_F_ADJ_ROOM_FIXED_GSO))
 		return TC_ACT_SHOT;
 
 	return TC_ACT_OK;
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index 9e18754f23547..cda5317790d24 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -35,6 +35,12 @@ setup() {
 	ip -netns "${ns1}" -6 addr add "${ns1_v6}/64" dev veth1 nodad
 	ip -netns "${ns2}" -6 addr add "${ns2_v6}/64" dev veth2 nodad
 
+	# 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
+
 	sleep 1
 
 	dd if=/dev/urandom of="${infile}" bs="${datalen}" count=1 status=none

From 75a1a9fa2e20de6319a19161ce4e2e1817d70e28 Mon Sep 17 00:00:00 2001
From: Willem de Bruijn <willemb@google.com>
Date: Fri, 22 Mar 2019 14:33:00 -0400
Subject: [PATCH 13/13] selftests/bpf: convert bpf tunnel test to encap modes

Make the tests correctly annotate skbs with tunnel metadata.

This makes the gso tests succeed. Enable them.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 .../selftests/bpf/progs/test_tc_tunnel.c      | 19 +++++++++++++++----
 tools/testing/selftests/bpf/test_tc_tunnel.sh | 10 ++++------
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 3b79dffb81037..f541c2de947d2 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -70,8 +70,13 @@ 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;
 
-	flags = BPF_F_ADJ_ROOM_FIXED_GSO;
-	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+	flags = BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_ENCAP_L3_IPV4;
+	if (with_gre) {
+		flags |= BPF_F_ADJ_ROOM_ENCAP_L4_GRE;
+		olen = sizeof(h_outer);
+	} else {
+		olen = sizeof(h_outer.ip);
+	}
 
 	/* add room between mac and network header */
 	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
@@ -119,8 +124,14 @@ 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;
-	olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
+	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);
+	}
+
 
 	/* add room between mac and network header */
 	if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, flags))
diff --git a/tools/testing/selftests/bpf/test_tc_tunnel.sh b/tools/testing/selftests/bpf/test_tc_tunnel.sh
index cda5317790d24..dcf3206269314 100755
--- a/tools/testing/selftests/bpf/test_tc_tunnel.sh
+++ b/tools/testing/selftests/bpf/test_tc_tunnel.sh
@@ -97,13 +97,11 @@ if [[ "$#" -eq "0" ]]; then
 	echo "ip6 gre"
 	$0 ipv6 ip6gre 100
 
-	# disabled until passes SKB_GSO_DODGY checks
-	# echo "ip gre gso"
-	# $0 ipv4 gre 2000
+	echo "ip gre gso"
+	$0 ipv4 gre 2000
 
-	# disabled until passes SKB_GSO_DODGY checks
-	# echo "ip6 gre gso"
-	# $0 ipv6 ip6gre 2000
+	echo "ip6 gre gso"
+	$0 ipv6 ip6gre 2000
 
 	echo "OK. All tests passed"
 	exit 0