[PATCH net-next 0/4] selftests: fcnal: Test SO_DONTROUTE socket option.

[PATCH net-next 0/4] selftests: fcnal: Test SO_DONTROUTE socket option.

[Guillaume Nault]

The objective is to cover kernel paths that use the RTO_ONLINK flag
in .flowi4_tos. This way we'll be able to safely remove this flag in
the future by properly setting .flowi4_scope instead. With these
selftests in place, we can make sure this won't introduce regressions.

For more context, the final objective is to convert .flowi4_tos to
dscp_t, to ensure that ECN bits don't influence route and fib-rule
lookups (see commit a410a0cf9885 ("ipv6: Define dscp_t and stop taking
ECN bits into account in fib6-rules")).

These selftests only cover IPv4, as SO_DONTROUTE has no effect on IPv6
sockets.

Guillaume Nault (4):
  selftests: Add SO_DONTROUTE option to nettest.
  selftests: fcnal: Test SO_DONTROUTE on TCP sockets.
  selftests: fcnal: Test SO_DONTROUTE on UDP sockets.
  selftests: fcnal: Test SO_DONTROUTE on raw and ping sockets.

 tools/testing/selftests/net/fcnal-test.sh | 105 ++++++++++++++++++++++
 tools/testing/selftests/net/nettest.c     |  32 ++++++-
 2 files changed, 135 insertions(+), 2 deletions(-)

-- 
2.30.2

[PATCH net-next 1/4] selftests: Add SO_DONTROUTE option to nettest.

[Guillaume Nault]

Add -G option to nettest. It allows to set the SO_DONTROUTE option to
the created sockets. This will be used by the following patches to test
the SO_DONTROUTE behaviour with TCP and UDP.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 tools/testing/selftests/net/nettest.c | 32 +++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index ee9a72982705..0b5b580e6eba 100644
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -76,7 +76,8 @@ struct sock_args {
 		     has_grp:1,
 		     has_expected_laddr:1,
 		     has_expected_raddr:1,
-		     bind_test_only:1;
+		     bind_test_only:1,
+		     dontroute:1;
 
 	unsigned short port;
 
@@ -611,6 +612,18 @@ static int set_dsfield(int sd, int version, int dsfield)
 	return 0;
 }
 
+static int set_dontroute(int sd)
+{
+	unsigned int one = 1;
+
+	if (setsockopt(sd, SOL_SOCKET, SO_DONTROUTE, &one, sizeof(one)) < 0) {
+		log_err_errno("setsockopt(SO_DONTROUTE)");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int str_to_uint(const char *str, int min, int max, unsigned int *value)
 {
 	int number;
@@ -1351,6 +1364,9 @@ static int msock_init(struct sock_args *args, int server)
 	if (set_dsfield(sd, AF_INET, args->dsfield) != 0)
 		goto out_err;
 
+	if (args->dontroute && set_dontroute(sd) != 0)
+		goto out_err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto out_err;
 	else if (args->use_setsockopt &&
@@ -1482,6 +1498,9 @@ static int lsock_init(struct sock_args *args)
 	if (set_dsfield(sd, args->version, args->dsfield) != 0)
 		goto err;
 
+	if (args->dontroute && set_dontroute(sd) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1698,6 +1717,9 @@ static int connectsock(void *addr, socklen_t alen, struct sock_args *args)
 	if (set_dsfield(sd, args->version, args->dsfield) != 0)
 		goto err;
 
+	if (args->dontroute && set_dontroute(sd) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1902,7 +1924,7 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args)
 	return client_status;
 }
 
-#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 GETOPT_STR  "sr:l:c:Q:Gp: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
 
@@ -1935,6 +1957,9 @@ static void print_usage(char *prog)
 	"    -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"
+	"    -G            don't use gateways: send packets only if\n"
+	"                  destination is on link (see SO_DONTROUTE in\n"
+	"                  socket(7))\n"
 	"    -x            configure XFRM policy on socket\n"
 	"\n"
 	"    -d dev        bind socket to given device name\n"
@@ -2020,6 +2045,9 @@ int main(int argc, char *argv[])
 			}
 			args.dsfield = tmp;
 			break;
+		case 'G':
+			args.dontroute = 1;
+			break;
 		case 'p':
 			if (str_to_uint(optarg, 1, 65535, &tmp) != 0) {
 				fprintf(stderr, "Invalid port\n");
-- 
2.30.2

Re: [PATCH net-next 1/4] selftests: Add SO_DONTROUTE option to nettest.

[David Ahern]

On Tue, May 09, 2023 at 02:02:36PM +0200, Guillaume Nault wrote:
> Add -G option to nettest. It allows to set the SO_DONTROUTE option to
> the created sockets. This will be used by the following patches to test
> the SO_DONTROUTE behaviour with TCP and UDP.
> 
> Signed-off-by: Guillaume Nault <gnault@redhat.com>
> ---
>  tools/testing/selftests/net/nettest.c | 32 +++++++++++++++++++++++++--
>  1 file changed, 30 insertions(+), 2 deletions(-)
> 

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

[PATCH net-next 2/4] selftests: fcnal: Test SO_DONTROUTE on TCP sockets.

[Guillaume Nault]

Use nettest -G to test the kernel behaviour with TCP sockets having the
SO_DONTROUTE option. Sending packets to a neighbour (on link) host,
should work. When the host is behind a router, sending should fail.

Client and server sockets are tested independently, so that we can
cover different TCP kernel paths.

SO_DONTROUTE also affects the syncookies path. So ipv4_tcp_dontroute()
is made to work with or without syncookies, to cover both paths.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 tools/testing/selftests/net/fcnal-test.sh | 70 +++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 21ca91473c09..1f8939fbb021 100755
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -1098,6 +1098,73 @@ test_ipv4_md5_vrf__global_server__bind_ifindex0()
 	set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
 }
 
+ipv4_tcp_dontroute()
+{
+	local syncookies=$1
+	local nsa_syncookies
+	local nsb_syncookies
+	local a
+
+	#
+	# Link local connection tests (SO_DONTROUTE).
+	# Connections should succeed only when the remote IP address is
+	# on link (doesn't need to be routed through a gateway).
+	#
+
+	nsa_syncookies=$(ip netns exec "${NSA}" sysctl -n net.ipv4.tcp_syncookies)
+	nsb_syncookies=$(ip netns exec "${NSB}" sysctl -n net.ipv4.tcp_syncookies)
+	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+
+	# Test with eth1 address (on link).
+
+	a=${NSB_IP}
+	log_start
+	run_cmd_nsb nettest -s &
+	sleep 1
+	run_cmd nettest -r ${a} -G
+	log_test_addr ${a} $? 0 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+	a=${NSB_IP}
+	log_start
+	# Ensure previous nettest server exited, so that it won't respond (we
+	# really want to test the -G option on the server).
+	wait
+	run_cmd_nsb nettest -s -G &
+	sleep 1
+	run_cmd nettest -r ${a}
+	log_test_addr ${a} $? 0 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+	# Test with loopback address (routed).
+	#
+	# The client would use the eth1 address as source IP by default.
+	# Therefore, we need to use the -c option here, to force the use of the
+	# routed (loopback) address as source IP (so that the server will try
+	# to respond to a routed address and not a link local one).
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Should fail 'Network is unreachable' since server is not on link"
+	run_cmd_nsb nettest -s &
+	sleep 1
+	run_cmd nettest -c ${NSA_LO_IP} -r ${a} -G
+	log_test_addr ${a} $? 1 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Should timeout since server cannot respond (client is not on link)"
+	# Ensure previous nettest server exited, so that it won't respond (we
+	# really want to test the -G option on the server).
+	wait
+	run_cmd_nsb nettest -s -G &
+	sleep 1
+	run_cmd nettest -c ${NSA_LO_IP} -r ${a}
+	log_test_addr ${a} $? 2 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${nsb_syncookies}
+	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${nsa_syncookies}
+}
+
 ipv4_tcp_novrf()
 {
 	local a
@@ -1217,6 +1284,9 @@ ipv4_tcp_novrf()
 	log_test_addr ${a} $? 1 "No server, device client, local conn"
 
 	ipv4_tcp_md5_novrf
+
+	ipv4_tcp_dontroute 0
+	ipv4_tcp_dontroute 2
 }
 
 ipv4_tcp_vrf()
-- 
2.30.2

Re: [PATCH net-next 2/4] selftests: fcnal: Test SO_DONTROUTE on TCP sockets.

[David Ahern]

On Tue, May 09, 2023 at 02:02:37PM +0200, Guillaume Nault wrote:
> diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
> index 21ca91473c09..1f8939fbb021 100755
> --- a/tools/testing/selftests/net/fcnal-test.sh
> +++ b/tools/testing/selftests/net/fcnal-test.sh
> @@ -1098,6 +1098,73 @@ test_ipv4_md5_vrf__global_server__bind_ifindex0()
>  	set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
>  }
>  
> +ipv4_tcp_dontroute()
> +{
> +	local syncookies=$1
> +	local nsa_syncookies
> +	local nsb_syncookies
> +	local a
> +
> +	#
> +	# Link local connection tests (SO_DONTROUTE).
> +	# Connections should succeed only when the remote IP address is
> +	# on link (doesn't need to be routed through a gateway).
> +	#
> +
> +	nsa_syncookies=$(ip netns exec "${NSA}" sysctl -n net.ipv4.tcp_syncookies)
> +	nsb_syncookies=$(ip netns exec "${NSB}" sysctl -n net.ipv4.tcp_syncookies)
> +	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
> +	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
> +
> +	# Test with eth1 address (on link).
> +
> +	a=${NSB_IP}
> +	log_start
> +	run_cmd_nsb nettest -s &
> +	sleep 1

rather than propagate the sleep for new tests, you try adding these
tests using a single nettest instance that takes both server and client
arguments and does the netns switch internally.

Re: [PATCH net-next 2/4] selftests: fcnal: Test SO_DONTROUTE on TCP sockets.

[Guillaume Nault]

On Tue, May 09, 2023 at 09:32:46AM -0600, David Ahern wrote:
> On Tue, May 09, 2023 at 02:02:37PM +0200, Guillaume Nault wrote:
> > diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
> > index 21ca91473c09..1f8939fbb021 100755
> > --- a/tools/testing/selftests/net/fcnal-test.sh
> > +++ b/tools/testing/selftests/net/fcnal-test.sh
> > @@ -1098,6 +1098,73 @@ test_ipv4_md5_vrf__global_server__bind_ifindex0()
> >  	set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
> >  }
> >  
> > +ipv4_tcp_dontroute()
> > +{
> > +	local syncookies=$1
> > +	local nsa_syncookies
> > +	local nsb_syncookies
> > +	local a
> > +
> > +	#
> > +	# Link local connection tests (SO_DONTROUTE).
> > +	# Connections should succeed only when the remote IP address is
> > +	# on link (doesn't need to be routed through a gateway).
> > +	#
> > +
> > +	nsa_syncookies=$(ip netns exec "${NSA}" sysctl -n net.ipv4.tcp_syncookies)
> > +	nsb_syncookies=$(ip netns exec "${NSB}" sysctl -n net.ipv4.tcp_syncookies)
> > +	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
> > +	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
> > +
> > +	# Test with eth1 address (on link).
> > +
> > +	a=${NSB_IP}
> > +	log_start
> > +	run_cmd_nsb nettest -s &
> > +	sleep 1
> 
> rather than propagate the sleep for new tests, you try adding these
> tests using a single nettest instance that takes both server and client
> arguments and does the netns switch internally.

Okay. That also means adding more options to nettest, to independently
set SO_DONTROUTE on the server or on the client. We're getting short of
one letter options, so I'll probably use long ones.

[PATCH net-next 4/4] selftests: fcnal: Test SO_DONTROUTE on raw and ping sockets.

[Guillaume Nault]

Use ping -r to test the kernel behaviour with raw and ping sockets
having the SO_DONTROUTE option.

Since ipv4_ping_novrf() is called with different values of
net.ipv4.ping_group_range, then it tests both raw and ping sockets
(ping uses ping sockets if its user ID belongs to ping_group_range
and raw sockets otherwise).

With both socket types, sending packets to a neighbour (on link) host,
should work. When the host is behind a router, sending should fail.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 tools/testing/selftests/net/fcnal-test.sh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 23672cba8781..3321d1971bd8 100755
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -584,6 +584,20 @@ ipv4_ping_novrf()
 		log_test_addr ${a} $? 0 "ping out, address bind"
 	done
 
+	#
+	# out, but don't use gateway if peer is not on link
+	#
+	a=${NSB_IP}
+	log_start
+	run_cmd ping -c 1 -w 1 -r ${a}
+	log_test_addr ${a} $? 0 "ping out (don't route), peer on link"
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Fails since peer is not on link"
+	run_cmd ping -c 1 -w 1 -r ${a}
+	log_test_addr ${a} $? 1 "ping out (don't route), peer not on link"
+
 	#
 	# in
 	#
-- 
2.30.2

[PATCH net-next 3/4] selftests: fcnal: Test SO_DONTROUTE on UDP sockets.

[Guillaume Nault]

Use nettest -G to test the kernel behaviour with UDP sockets having the
SO_DONTROUTE option. Sending packets to a neighbour (on link) host,
should work. When the host is behind a router, sending should fail.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
---
 tools/testing/selftests/net/fcnal-test.sh | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 1f8939fbb021..23672cba8781 100755
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -1655,6 +1655,27 @@ ipv4_udp_novrf()
 	log_start
 	run_cmd nettest -D -d ${NSA_DEV} -r ${a}
 	log_test_addr ${a} $? 2 "No server, device client, local conn"
+
+	#
+	# Link local connection tests (SO_DONTROUTE).
+	# Connections should succeed only when the remote IP address is
+	# on link (doesn't need to be routed through a gateway).
+	#
+
+	a=${NSB_IP}
+	log_start
+	run_cmd_nsb nettest -D -s &
+	sleep 1
+	run_cmd nettest -D -r ${a} -G
+	log_test_addr ${a} $? 0 "SO_DONTROUTE client"
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Should fail 'Network is unreachable' since server is not on link"
+	run_cmd_nsb nettest -D -s &
+	sleep 1
+	run_cmd nettest -D -r ${a} -G
+	log_test_addr ${a} $? 1 "SO_DONTROUTE client"
 }
 
 ipv4_udp_vrf()
-- 
2.30.2