[PATCH net 0/3] ipv6: Fix socket connection with DSCP fib-rules.

[PATCH net 0/3] ipv6: Fix socket connection with DSCP fib-rules.

[Guillaume Nault]

The "flowlabel" field of struct flowi6 is used to store both the actual
flow label and the DS Field (or Traffic Class). However the .connect
handlers of datagram and TCP sockets don't set the DS Field part when
doing their route lookup. This breaks fib-rules that match on DSCP.

Guillaume Nault (3):
  ipv6: Fix datagram socket connect with DSCP.
  ipv6: Fix tcp socket connect with DSCP.
  selftests: fib_rule_tests: Test UDP and TCP connections with DSCP
    rules.

 net/ipv6/datagram.c                           |   2 +-
 net/ipv6/tcp_ipv6.c                           |   1 +
 tools/testing/selftests/net/fib_rule_tests.sh | 128 +++++++++++++++++-
 tools/testing/selftests/net/nettest.c         |  51 ++++++-
 4 files changed, 179 insertions(+), 3 deletions(-)

-- 
2.30.2

[PATCH net 1/3] ipv6: Fix datagram socket connection with DSCP.

[Guillaume Nault]

Take into account the IPV6_TCLASS socket option (DSCP) in
ip6_datagram_flow_key_init(). Otherwise fib6_rule_match() can't
properly match the DSCP value, resulting in invalid route lookup.

For example:

  ip route add unreachable table main 2001:db8::10/124

  ip route add table 100 2001:db8::10/124 dev eth0
  ip -6 rule add dsfield 0x04 table 100

  echo test | socat - UDP6:[2001:db8::11]:54321,ipv6-tclass=0x04

Without this patch, socat fails at connect() time ("No route to host")
because the fib-rule doesn't jump to table 100 and the lookup ends up
being done in the main table.

Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 net/ipv6/datagram.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index e624497fa992..9b6818453afe 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -51,7 +51,7 @@ static void ip6_datagram_flow_key_init(struct flowi6 *fl6, struct sock *sk)
 	fl6->flowi6_mark = sk->sk_mark;
 	fl6->fl6_dport = inet->inet_dport;
 	fl6->fl6_sport = inet->inet_sport;
-	fl6->flowlabel = np->flow_label;
+	fl6->flowlabel = ip6_make_flowinfo(np->tclass, np->flow_label);
 	fl6->flowi6_uid = sk->sk_uid;
 
 	if (!oif)
-- 
2.30.2

Re: [PATCH net 1/3] ipv6: Fix datagram socket connection with DSCP.

[Eric Dumazet]

On Wed, Feb 8, 2023 at 6:14 PM Guillaume Nault <gnault@redhat.com> wrote:
>
> Take into account the IPV6_TCLASS socket option (DSCP) in
> ip6_datagram_flow_key_init(). Otherwise fib6_rule_match() can't
> properly match the DSCP value, resulting in invalid route lookup.
>

>
> Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
> Signed-off-by: Guillaume Nault <gnault@redhat.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH net 1/3] ipv6: Fix datagram socket connection with DSCP.

[David Ahern]

On 2/8/23 10:13 AM, Guillaume Nault wrote:
> Take into account the IPV6_TCLASS socket option (DSCP) in
> ip6_datagram_flow_key_init(). Otherwise fib6_rule_match() can't
> properly match the DSCP value, resulting in invalid route lookup.
> 
> For example:
> 
>   ip route add unreachable table main 2001:db8::10/124
> 
>   ip route add table 100 2001:db8::10/124 dev eth0
>   ip -6 rule add dsfield 0x04 table 100
> 
>   echo test | socat - UDP6:[2001:db8::11]:54321,ipv6-tclass=0x04
> 
> Without this patch, socat fails at connect() time ("No route to host")
> because the fib-rule doesn't jump to table 100 and the lookup ends up
> being done in the main table.
> 
> Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---
>  net/ipv6/datagram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH net 2/3] ipv6: Fix tcp socket connection with DSCP.

[Guillaume Nault]

Take into account the IPV6_TCLASS socket option (DSCP) in
tcp_v6_connect(). Otherwise fib6_rule_match() can't properly
match the DSCP value, resulting in invalid route lookup.

For example:

  ip route add unreachable table main 2001:db8::10/124

  ip route add table 100 2001:db8::10/124 dev eth0
  ip -6 rule add dsfield 0x04 table 100

  echo test | socat - TCP6:[2001:db8::11]:54321,ipv6-tclass=0x04

Without this patch, socat fails at connect() time ("No route to host")
because the fib-rule doesn't jump to table 100 and the lookup ends up
being done in the main table.

Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 net/ipv6/tcp_ipv6.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 11b736a76bd7..0d25e813288d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -272,6 +272,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 	fl6.flowi6_proto = IPPROTO_TCP;
 	fl6.daddr = sk->sk_v6_daddr;
 	fl6.saddr = saddr ? *saddr : np->saddr;
+	fl6.flowlabel = ip6_make_flowinfo(np->tclass, np->flow_label);
 	fl6.flowi6_oif = sk->sk_bound_dev_if;
 	fl6.flowi6_mark = sk->sk_mark;
 	fl6.fl6_dport = usin->sin6_port;
-- 
2.30.2

Re: [PATCH net 2/3] ipv6: Fix tcp socket connection with DSCP.

[Eric Dumazet]

On Wed, Feb 8, 2023 at 6:14 PM Guillaume Nault <gnault@redhat.com> wrote:
>
> Take into account the IPV6_TCLASS socket option (DSCP) in
> tcp_v6_connect(). Otherwise fib6_rule_match() can't properly
> match the DSCP value, resulting in invalid route lookup.
>
> being done in the main table.
>
> Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.

Re: [PATCH net 2/3] ipv6: Fix tcp socket connection with DSCP.

[David Ahern]

On 2/8/23 10:14 AM, Guillaume Nault wrote:
> Take into account the IPV6_TCLASS socket option (DSCP) in
> tcp_v6_connect(). Otherwise fib6_rule_match() can't properly
> match the DSCP value, resulting in invalid route lookup.
> 
> For example:
> 
>   ip route add unreachable table main 2001:db8::10/124
> 
>   ip route add table 100 2001:db8::10/124 dev eth0
>   ip -6 rule add dsfield 0x04 table 100
> 
>   echo test | socat - TCP6:[2001:db8::11]:54321,ipv6-tclass=0x04
> 
> Without this patch, socat fails at connect() time ("No route to host")
> because the fib-rule doesn't jump to table 100 and the lookup ends up
> being done in the main table.
> 
> Fixes: 2cc67cc731d9 ("[IPV6] ROUTE: Routing by Traffic Class.")
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---
>  net/ipv6/tcp_ipv6.c | 1 +
>  1 file changed, 1 insertion(+)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

[PATCH net 3/3] selftests: fib_rule_tests: Test UDP and TCP connections with DSCP rules.

[Guillaume Nault]

Add the fib_rule6_send and fib_rule4_send tests to verify that DSCP
values are properly taken into account when UDP or TCP sockets try to
connect().

Tests are done with nettest, which needs a new option to specify
the DS Field value of the socket being tested. This new option is
named '-Q', in reference to the similar option used by ping.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 tools/testing/selftests/net/fib_rule_tests.sh | 128 +++++++++++++++++-
 tools/testing/selftests/net/nettest.c         |  51 ++++++-
 2 files changed, 177 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/fib_rule_tests.sh b/tools/testing/selftests/net/fib_rule_tests.sh
index c245476fa29d..63c3eaec8d30 100755
--- a/tools/testing/selftests/net/fib_rule_tests.sh
+++ b/tools/testing/selftests/net/fib_rule_tests.sh
@@ -10,8 +10,10 @@ ret=0
 
 PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}
 IP="ip -netns testns"
+IP_PEER="ip -netns peerns"
 
 RTABLE=100
+RTABLE_PEER=101
 GW_IP4=192.51.100.2
 SRC_IP=192.51.100.3
 GW_IP6=2001:db8:1::2
@@ -20,7 +22,9 @@ SRC_IP6=2001:db8:1::3
 DEV_ADDR=192.51.100.1
 DEV_ADDR6=2001:db8:1::1
 DEV=dummy0
-TESTS="fib_rule6 fib_rule4"
+TESTS="fib_rule6 fib_rule4 fib_rule6_connect fib_rule4_connect"
+
+SELFTEST_PATH=""
 
 log_test()
 {
@@ -52,6 +56,31 @@ log_section()
 	echo "######################################################################"
 }
 
+check_nettest()
+{
+	if which nettest > /dev/null 2>&1; then
+		return 0
+	fi
+
+	# Add the selftest directory to PATH if not already done
+	if [ "${SELFTEST_PATH}" = "" ]; then
+		SELFTEST_PATH="$(dirname $0)"
+		PATH="${PATH}:${SELFTEST_PATH}"
+
+		# Now retry with the new path
+		if which nettest > /dev/null 2>&1; then
+			return 0
+		fi
+
+		if [ "${ret}" -eq 0 ]; then
+			ret="${ksft_skip}"
+		fi
+		echo "nettest not found (try 'make -C ${SELFTEST_PATH} nettest')"
+	fi
+
+	return 1
+}
+
 setup()
 {
 	set -e
@@ -72,6 +101,39 @@ cleanup()
 	ip netns del testns
 }
 
+setup_peer()
+{
+	set -e
+
+	ip netns add peerns
+	$IP_PEER link set dev lo up
+
+	ip link add name veth0 netns testns type veth \
+		peer name veth1 netns peerns
+	$IP link set dev veth0 up
+	$IP_PEER link set dev veth1 up
+
+	$IP address add 192.0.2.10 peer 192.0.2.11/32 dev veth0
+	$IP_PEER address add 192.0.2.11 peer 192.0.2.10/32 dev veth1
+
+	$IP address add 2001:db8::10 peer 2001:db8::11/128 dev veth0 nodad
+	$IP_PEER address add 2001:db8::11 peer 2001:db8::10/128 dev veth1 nodad
+
+	$IP_PEER address add 198.51.100.11/32 dev lo
+	$IP route add table $RTABLE_PEER 198.51.100.11/32 via 192.0.2.11
+
+	$IP_PEER address add 2001:db8::1:11/128 dev lo
+	$IP route add table $RTABLE_PEER 2001:db8::1:11/128 via 2001:db8::11
+
+	set +e
+}
+
+cleanup_peer()
+{
+	$IP link del dev veth0
+	ip netns del peerns
+}
+
 fib_check_iproute_support()
 {
 	ip rule help 2>&1 | grep -q $1
@@ -190,6 +252,37 @@ fib_rule6_test()
 	fi
 }
 
+# Verify that the IPV6_TCLASS option of UDPv6 and TCPv6 sockets is properly
+# taken into account when connecting the socket and when sending packets.
+fib_rule6_connect_test()
+{
+	local dsfield
+
+	if ! check_nettest; then
+		echo "SKIP: Could not run test without nettest tool"
+		return
+	fi
+
+	setup_peer
+	$IP -6 rule add dsfield 0x04 table $RTABLE_PEER
+
+	# Combine the base DS Field value (0x04) with all possible ECN values
+	# (Not-ECT: 0, ECT(1): 1, ECT(0): 2, CE: 3).
+	# The ECN bits shouldn't influence the result of the test.
+	for dsfield in 0x04 0x05 0x06 0x07; do
+		nettest -q -6 -B -t 5 -N testns -O peerns -U -D \
+			-Q "${dsfield}" -l 2001:db8::1:11 -r 2001:db8::1:11
+		log_test $? 0 "rule6 dsfield udp connect (dsfield ${dsfield})"
+
+		nettest -q -6 -B -t 5 -N testns -O peerns -Q "${dsfield}" \
+			-l 2001:db8::1:11 -r 2001:db8::1:11
+		log_test $? 0 "rule6 dsfield tcp connect (dsfield ${dsfield})"
+	done
+
+	$IP -6 rule del dsfield 0x04 table $RTABLE_PEER
+	cleanup_peer
+}
+
 fib_rule4_del()
 {
 	$IP rule del $1
@@ -296,6 +389,37 @@ fib_rule4_test()
 	fi
 }
 
+# Verify that the IP_TOS option of UDPv4 and TCPv4 sockets is properly taken
+# into account when connecting the socket and when sending packets.
+fib_rule4_connect_test()
+{
+	local dsfield
+
+	if ! check_nettest; then
+		echo "SKIP: Could not run test without nettest tool"
+		return
+	fi
+
+	setup_peer
+	$IP -4 rule add dsfield 0x04 table $RTABLE_PEER
+
+	# Combine the base DS Field value (0x04) with all possible ECN values
+	# (Not-ECT: 0, ECT(1): 1, ECT(0): 2, CE: 3).
+	# The ECN bits shouldn't influence the result of the test.
+	for dsfield in 0x04 0x05 0x06 0x07; do
+		nettest -q -B -t 5 -N testns -O peerns -D -U -Q "${dsfield}" \
+			-l 198.51.100.11 -r 198.51.100.11
+		log_test $? 0 "rule4 dsfield udp connect (dsfield ${dsfield})"
+
+		nettest -q -B -t 5 -N testns -O peerns -Q "${dsfield}" \
+			-l 198.51.100.11 -r 198.51.100.11
+		log_test $? 0 "rule4 dsfield tcp connect (dsfield ${dsfield})"
+	done
+
+	$IP -4 rule del dsfield 0x04 table $RTABLE_PEER
+	cleanup_peer
+}
+
 run_fibrule_tests()
 {
 	log_section "IPv4 fib rule"
@@ -345,6 +469,8 @@ do
 	case $t in
 	fib_rule6_test|fib_rule6)		fib_rule6_test;;
 	fib_rule4_test|fib_rule4)		fib_rule4_test;;
+	fib_rule6_connect_test|fib_rule6_connect)	fib_rule6_connect_test;;
+	fib_rule4_connect_test|fib_rule4_connect)	fib_rule4_connect_test;;
 
 	help) echo "Test names: $TESTS"; exit 0;;
 
diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index 7900fa98eccb..ee9a72982705 100644
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -87,6 +87,7 @@ struct sock_args {
 	int use_setsockopt;
 	int use_freebind;
 	int use_cmsg;
+	uint8_t dsfield;
 	const char *dev;
 	const char *server_dev;
 	int ifindex;
@@ -580,6 +581,36 @@ static int set_reuseaddr(int sd)
 	return rc;
 }
 
+static int set_dsfield(int sd, int version, int dsfield)
+{
+	if (!dsfield)
+		return 0;
+
+	switch (version) {
+	case AF_INET:
+		if (setsockopt(sd, SOL_IP, IP_TOS, &dsfield,
+			       sizeof(dsfield)) < 0) {
+			log_err_errno("setsockopt(IP_TOS)");
+			return -1;
+		}
+		break;
+
+	case AF_INET6:
+		if (setsockopt(sd, SOL_IPV6, IPV6_TCLASS, &dsfield,
+			       sizeof(dsfield)) < 0) {
+			log_err_errno("setsockopt(IPV6_TCLASS)");
+			return -1;
+		}
+		break;
+
+	default:
+		log_error("Invalid address family\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int str_to_uint(const char *str, int min, int max, unsigned int *value)
 {
 	int number;
@@ -1317,6 +1348,9 @@ static int msock_init(struct sock_args *args, int server)
 		       (char *)&one, sizeof(one)) < 0)
 		log_err_errno("Setting SO_BROADCAST error");
 
+	if (set_dsfield(sd, AF_INET, args->dsfield) != 0)
+		goto out_err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto out_err;
 	else if (args->use_setsockopt &&
@@ -1445,6 +1479,9 @@ static int lsock_init(struct sock_args *args)
 	if (set_reuseport(sd) != 0)
 		goto err;
 
+	if (set_dsfield(sd, args->version, args->dsfield) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1658,6 +1695,9 @@ static int connectsock(void *addr, socklen_t alen, struct sock_args *args)
 	if (set_reuseport(sd) != 0)
 		goto err;
 
+	if (set_dsfield(sd, args->version, args->dsfield) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1862,7 +1902,7 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args)
 	return client_status;
 }
 
-#define GETOPT_STR  "sr:l:c:p:t:g:P:DRn:M:X:m:d:I:BN:O:SUCi6xL:0:1:2:3:Fbqf"
+#define GETOPT_STR  "sr:l:c:Q:p:t:g:P:DRn:M:X:m:d:I:BN:O:SUCi6xL:0:1:2:3:Fbqf"
 #define OPT_FORCE_BIND_KEY_IFINDEX 1001
 #define OPT_NO_BIND_KEY_IFINDEX 1002
 
@@ -1893,6 +1933,8 @@ static void print_usage(char *prog)
 	"    -D|R          datagram (D) / raw (R) socket (default stream)\n"
 	"    -l addr       local address to bind to in server mode\n"
 	"    -c addr       local address to bind to in client mode\n"
+	"    -Q dsfield    DS Field value of the socket (the IP_TOS or\n"
+	"                  IPV6_TCLASS socket option)\n"
 	"    -x            configure XFRM policy on socket\n"
 	"\n"
 	"    -d dev        bind socket to given device name\n"
@@ -1971,6 +2013,13 @@ int main(int argc, char *argv[])
 			args.has_local_ip = 1;
 			args.client_local_addr_str = optarg;
 			break;
+		case 'Q':
+			if (str_to_uint(optarg, 0, 255, &tmp) != 0) {
+				fprintf(stderr, "Invalid DS Field\n");
+				return 1;
+			}
+			args.dsfield = tmp;
+			break;
 		case 'p':
 			if (str_to_uint(optarg, 1, 65535, &tmp) != 0) {
 				fprintf(stderr, "Invalid port\n");
-- 
2.30.2

Re: [PATCH net 3/3] selftests: fib_rule_tests: Test UDP and TCP connections with DSCP rules.

[David Ahern]

On 2/8/23 10:14 AM, Guillaume Nault wrote:
> Add the fib_rule6_send and fib_rule4_send tests to verify that DSCP
> values are properly taken into account when UDP or TCP sockets try to
> connect().
> 
> Tests are done with nettest, which needs a new option to specify
> the DS Field value of the socket being tested. This new option is
> named '-Q', in reference to the similar option used by ping.
> 
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---
>  tools/testing/selftests/net/fib_rule_tests.sh | 128 +++++++++++++++++-
>  tools/testing/selftests/net/nettest.c         |  51 ++++++-
>  2 files changed, 177 insertions(+), 2 deletions(-)
> 


Reviewed-by: David Ahern <dsahern@kernel.org>

Re: [PATCH net 0/3] ipv6: Fix socket connection with DSCP fib-rules.

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 8 Feb 2023 18:13:56 +0100 you wrote:
> The "flowlabel" field of struct flowi6 is used to store both the actual
> flow label and the DS Field (or Traffic Class). However the .connect
> handlers of datagram and TCP sockets don't set the DS Field part when
> doing their route lookup. This breaks fib-rules that match on DSCP.
> 
> Guillaume Nault (3):
>   ipv6: Fix datagram socket connect with DSCP.
>   ipv6: Fix tcp socket connect with DSCP.
>   selftests: fib_rule_tests: Test UDP and TCP connections with DSCP
>     rules.
> 
> [...]

Here is the summary with links:
  - [net,1/3] ipv6: Fix datagram socket connection with DSCP.
    https://git.kernel.org/netdev/net/c/e010ae08c71f
  - [net,2/3] ipv6: Fix tcp socket connection with DSCP.
    https://git.kernel.org/netdev/net/c/8230680f36fd
  - [net,3/3] selftests: fib_rule_tests: Test UDP and TCP connections with DSCP rules.
    https://git.kernel.org/netdev/net/c/c21a20d9d102

You are awesome, thank you!
-- 
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