* [PATCH net-next 1/2] net: ipv6: seg6: report lwtunnel setup errors via extack
2026-09-18 15:35 [PATCH net-next 0/2] net: ipv6: seg6: extack messages for lwtunnel setup Gabriel Goller
@ 2026-09-18 15:35 ` Gabriel Goller
2026-09-18 15:35 ` [PATCH net-next 2/2] selftests: seg6: check extack messages on SRv6 lwtunnel setup Gabriel Goller
1 sibling, 0 replies; 4+ messages in thread
From: Gabriel Goller @ 2026-09-18 15:35 UTC (permalink / raw)
To: Andrea Mayer, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Simon Horman, Shuah Khan
Cc: netdev, linux-kernel, linux-kselftest
seg6_build_state() rejected invalid configurations with a generic
-EINVAL, so "ip route add ... encap seg6 ..." always reported "Invalid
argument".
Attach an extack message to each of them. The checks themselves and
their return values are unchanged.
Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
net/ipv6/seg6_iptunnel.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 61c6a27bf202..e7f75970e26e 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -756,8 +756,12 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
struct seg6_lwt *slwt;
int err;
- if (family != AF_INET && family != AF_INET6)
+ if (family != AF_INET && family != AF_INET6) {
+ NL_SET_ERR_MSG(
+ extack,
+ "unsupported address family for SRv6 encapsulation");
return -EINVAL;
+ }
err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
seg6_iptunnel_policy, extack);
@@ -765,8 +769,10 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
if (err < 0)
return err;
- if (!tb[SEG6_IPTUNNEL_SRH])
+ if (!tb[SEG6_IPTUNNEL_SRH]) {
+ NL_SET_ERR_MSG(extack, "missing SRv6 SRH attribute");
return -EINVAL;
+ }
tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
@@ -776,13 +782,18 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
*/
min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
sizeof(struct in6_addr);
- if (tuninfo_len < min_size)
+ if (tuninfo_len < min_size) {
+ NL_SET_ERR_MSG(extack, "truncated SRv6 SRH attribute");
return -EINVAL;
+ }
switch (tuninfo->mode) {
case SEG6_IPTUN_MODE_INLINE:
- if (family != AF_INET6)
+ if (family != AF_INET6) {
+ NL_SET_ERR_MSG(extack,
+ "inline mode requires an IPv6 route");
return -EINVAL;
+ }
if (tb[SEG6_IPTUNNEL_SRC]) {
NL_SET_ERR_MSG(extack, "incompatible mode for tunsrc");
@@ -798,12 +809,16 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
case SEG6_IPTUN_MODE_L2ENCAP_RED:
break;
default:
+ NL_SET_ERR_MSG(extack, "invalid SRv6 encapsulation mode");
return -EINVAL;
}
/* verify that SRH is consistent */
- if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
+ if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo),
+ false)) {
+ NL_SET_ERR_MSG(extack, "invalid SRv6 segment routing header");
return -EINVAL;
+ }
newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
if (!newts)
--
2.47.3
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH net-next 2/2] selftests: seg6: check extack messages on SRv6 lwtunnel setup
2026-09-18 15:35 [PATCH net-next 0/2] net: ipv6: seg6: extack messages for lwtunnel setup Gabriel Goller
2026-09-18 15:35 ` [PATCH net-next 1/2] net: ipv6: seg6: report lwtunnel setup errors via extack Gabriel Goller
@ 2026-09-18 15:35 ` Gabriel Goller
2026-09-18 22:02 ` Jakub Kicinski
1 sibling, 1 reply; 4+ messages in thread
From: Gabriel Goller @ 2026-09-18 15:35 UTC (permalink / raw)
To: Andrea Mayer, David S . Miller, Eric Dumazet, Jakub Kicinski,
Paolo Abeni, Simon Horman, Shuah Khan
Cc: netdev, linux-kernel, linux-kselftest
Add a ksft/ynl test that shoves invalid RTA_ENCAP payloads to
RTM_NEWROUTE and asserts both the errno and the extack message are
correct.Also verify that the rejected route was not installed.
Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
tools/testing/selftests/net/Makefile | 1 +
.../selftests/net/srv6_iptunnel_extack.py | 168 ++++++++++++++++++
2 files changed, 169 insertions(+)
create mode 100755 tools/testing/selftests/net/srv6_iptunnel_extack.py
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 3ee3378f8b26..45639f46b003 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -101,6 +101,7 @@ TEST_PROGS := \
srv6_hencap_red_l3vpn_test.sh \
srv6_hl2encap_red_l2vpn_test.sh \
srv6_iptunnel_cache.sh \
+ srv6_iptunnel_extack.py \
stress_reuseport_listen.sh \
tcp_ecmp_failover.sh \
tcp_fastopen_backup_key.sh \
diff --git a/tools/testing/selftests/net/srv6_iptunnel_extack.py b/tools/testing/selftests/net/srv6_iptunnel_extack.py
new file mode 100755
index 000000000000..77e708a08c3e
--- /dev/null
+++ b/tools/testing/selftests/net/srv6_iptunnel_extack.py
@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+#
+# author: Gabriel Goller <g.goller@proxmox.com>
+
+"""Exercise SRv6 tunnel validation with invalid netlink attributes."""
+
+import errno
+import os
+import socket
+import struct
+from contextlib import contextmanager
+
+from lib.py import KsftNamedVariant, KsftSkipEx, Netlink, NetNS, NetNSEnter
+from lib.py import NlError, RtnlRouteFamily, ip, ksft_eq, ksft_exit, ksft_raises
+from lib.py import ksft_run, ksft_variants
+
+
+LWTUNNEL_ENCAP_SEG6 = 5
+SEG6_IPTUNNEL_SRH = 1
+SEG6_IPTUNNEL_SRC = 2
+SEG6_IPTUNNEL_TABLE = 3
+SEG6_IPTUN_MODE_INLINE = 0
+SEG6_IPTUN_MODE_ENCAP = 1
+SEG6_IPTUN_MODE_L2ENCAP = 2
+SEG6_IPTUN_MODE_ENCAP_RED = 3
+SEG6_IPTUN_MODE_L2ENCAP_RED = 4
+
+
+def encap(mode=SEG6_IPTUN_MODE_ENCAP, hdrlen=2, routing_type=4):
+ # seg6_iptunnel_encap followed by an SRH containing one segment.
+ srh = struct.pack('!BBBBBBH', 0, hdrlen, routing_type, 0, 0, 0, 0)
+ srh += socket.inet_pton(socket.AF_INET6, '2001:db8::1')
+ return struct.pack('=i', mode) + srh
+
+
+def nlattr(attr_type, payload):
+ length = 4 + len(payload)
+ return (struct.pack('=HH', length, attr_type) + payload +
+ bytes(-length % 4))
+
+
+def route(family, oif, payload, tunsrc=None, table=None):
+ attrs = b''
+ if payload is not None:
+ attrs += nlattr(SEG6_IPTUNNEL_SRH, payload)
+ if tunsrc is not None:
+ attrs += nlattr(SEG6_IPTUNNEL_SRC,
+ socket.inet_pton(socket.AF_INET6, tunsrc))
+ if table is not None:
+ attrs += nlattr(SEG6_IPTUNNEL_TABLE, struct.pack('=I', table))
+
+ return {
+ 'rtm-family': family,
+ 'rtm-dst-len': 32 if family == socket.AF_INET else 128,
+ 'rtm-table': 254,
+ 'rtm-protocol': 4, # RTPROT_STATIC
+ 'rtm-type': 1, # RTN_UNICAST
+ 'dst': '192.0.2.1' if family == socket.AF_INET else '2001:db8:1::1',
+ 'oif': oif,
+ 'encap-type': LWTUNNEL_ENCAP_SEG6,
+ 'encap': attrs,
+ }
+
+
+def add_route(rtnl, attrs):
+ rtnl.newroute(attrs.copy(),
+ flags=[Netlink.NLM_F_CREATE, Netlink.NLM_F_EXCL])
+
+
+def matching_routes(rtnl, attrs):
+ routes = rtnl.getroute({'rtm-family': attrs['rtm-family']}, dump=True)
+ return [entry for entry in routes
+ if entry.get('dst') == attrs['dst'] and
+ entry['rtm-table'] == attrs['rtm-table']]
+
+
+@contextmanager
+def setup():
+ if os.geteuid() != 0:
+ raise KsftSkipEx('Root privileges are required')
+
+ with NetNS() as ns, NetNSEnter(str(ns)):
+ ip('link set lo up')
+ oif = socket.if_nametoindex('lo')
+ rtnl = RtnlRouteFamily()
+ try:
+ # Probe with a valid route so missing SRv6 support is a skip,
+ # whereas missing diagnostics remain a test failure.
+ probe = route(socket.AF_INET6, oif, encap())
+ try:
+ add_route(rtnl, probe)
+ except NlError as error:
+ if error.error == errno.EOPNOTSUPP:
+ raise KsftSkipEx('SRv6 tunnels are not supported') from error
+ raise
+ rtnl.delroute(probe.copy())
+ yield rtnl, oif
+ finally:
+ rtnl.close()
+
+
+# (name, SRH payload, extra encap attributes, expected extack message)
+INVALID = [
+ ('missing_srh', None, {}, 'missing SRv6 SRH attribute'),
+ ('empty_srh', b'', {}, 'truncated SRv6 SRH attribute'),
+ ('short_srh', encap()[:-1], {}, 'truncated SRv6 SRH attribute'),
+ ('invalid_mode', encap(mode=255), {}, 'invalid SRv6 encapsulation mode'),
+ ('invalid_type', encap(routing_type=0), {},
+ 'invalid SRv6 segment routing header'),
+ ('invalid_length', encap(hdrlen=4), {},
+ 'invalid SRv6 segment routing header'),
+ ('invalid_tunsrc', encap(), {'tunsrc': '::'}, 'invalid tunsrc address'),
+ ('invalid_table', encap(), {'table': 0}, 'invalid lookup table'),
+]
+
+
+@ksft_variants([
+ KsftNamedVariant(f'{name}_{af_name}', family, payload, extra, message)
+ for name, payload, extra, message in INVALID
+ for af_name, family in [('ipv4', socket.AF_INET), ('ipv6', socket.AF_INET6)]
+] + [KsftNamedVariant('inline_ipv4', socket.AF_INET,
+ encap(mode=SEG6_IPTUN_MODE_INLINE), {},
+ 'inline mode requires an IPv6 route'),
+ # Inline mode rejects a non-IPv6 route before it looks at tunsrc,
+ # so only IPv6 reaches the tunsrc check.
+ KsftNamedVariant('inline_tunsrc_ipv6', socket.AF_INET6,
+ encap(mode=SEG6_IPTUN_MODE_INLINE),
+ {'tunsrc': '2001:db8::2'},
+ 'incompatible mode for tunsrc')])
+def invalid_config(family, payload, extra, message):
+ with setup() as (rtnl, oif):
+ attrs = route(family, oif, payload, **extra)
+ with ksft_raises(NlError) as caught:
+ add_route(rtnl, attrs)
+ ksft_eq(matching_routes(rtnl, attrs), [], 'Rejected route was installed')
+ if caught.exception is None:
+ return
+ ksft_eq(caught.exception.error, errno.EINVAL)
+ ksft_eq((caught.exception.nl_msg.extack or {}).get('msg'), message)
+
+
+@ksft_variants([
+ KsftNamedVariant(f'{name}_{af_name}', family, mode)
+ for name, mode in [('inline', SEG6_IPTUN_MODE_INLINE),
+ ('encap', SEG6_IPTUN_MODE_ENCAP),
+ ('l2encap', SEG6_IPTUN_MODE_L2ENCAP),
+ ('encap_red', SEG6_IPTUN_MODE_ENCAP_RED),
+ ('l2encap_red', SEG6_IPTUN_MODE_L2ENCAP_RED)]
+ for af_name, family in [('ipv4', socket.AF_INET), ('ipv6', socket.AF_INET6)]
+ if mode != SEG6_IPTUN_MODE_INLINE or family == socket.AF_INET6
+])
+def valid_config(family, mode):
+ with setup() as (rtnl, oif):
+ attrs = route(family, oif, encap(mode=mode))
+ add_route(rtnl, attrs)
+ routes = matching_routes(rtnl, attrs)
+ ksft_eq(len(routes), 1)
+ if routes:
+ ksft_eq(routes[0].get('encap-type'), LWTUNNEL_ENCAP_SEG6)
+ ksft_eq(routes[0].get('encap'), attrs['encap'])
+ rtnl.delroute(attrs.copy())
+ ksft_eq(matching_routes(rtnl, attrs), [])
+
+
+if __name__ == '__main__':
+ ksft_run([invalid_config, valid_config])
+ ksft_exit()
--
2.47.3
^ permalink raw reply [flat|nested] 4+ messages in thread