git: 3d39eadcdeb3 - main - ipfw: fix IPv6 flow label matching
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Date: Tue, 12 May 2026 07:48:45 UTC
The branch main has been updated by ae:
URL: https://cgit.FreeBSD.org/src/commit/?id=3d39eadcdeb301e95abdc94b1ad5d1255fa0f446
commit 3d39eadcdeb301e95abdc94b1ad5d1255fa0f446
Author: Boris Lytochkin <lytboris@gmail.com>
AuthorDate: 2026-05-12 07:44:10 +0000
Commit: Andrey V. Elsukov <ae@FreeBSD.org>
CommitDate: 2026-05-12 07:44:10 +0000
ipfw: fix IPv6 flow label matching
* do not require just only ip6 proto for flow-id opcode in ipfw(8).
ipv6-icmp, tcp, udp should be fine too.
* fix off-by-one bug leading to out-of-bounds read.
* apply IPV6_FLOWLABEL_MASK before comparison in flow6id_match(),
so flow-id opcode will match a specified flow label. No need to
take protocol version and traffic class into account.
* add the test to verify that opcode is working correctly.
Reviewed by: pouria
Obtained from: Yandex LLC
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D56869
---
sbin/ipfw/ipfw2.c | 5 +--
sys/netpfil/ipfw/ip_fw2.c | 4 +-
tests/sys/netpfil/common/pft_ping.py | 13 +++++-
tests/sys/netpfil/ipfw/Makefile | 1 +
tests/sys/netpfil/ipfw/ipv6-flow-id.sh | 78 ++++++++++++++++++++++++++++++++++
5 files changed, 95 insertions(+), 6 deletions(-)
diff --git a/sbin/ipfw/ipfw2.c b/sbin/ipfw/ipfw2.c
index e0e1339a1dce..06a1ee937cd7 100644
--- a/sbin/ipfw/ipfw2.c
+++ b/sbin/ipfw/ipfw2.c
@@ -5515,10 +5515,7 @@ read_options:
break;
case TOK_FLOWID:
- if (proto != IPPROTO_IPV6 )
- errx( EX_USAGE, "flow-id filter is active "
- "only for ipv6 protocol\n");
- fill_flow6( (ipfw_insn_u32 *) cmd, *av, cblen);
+ fill_flow6(insntod(cmd, u32), *av, cblen);
av++;
break;
diff --git a/sys/netpfil/ipfw/ip_fw2.c b/sys/netpfil/ipfw/ip_fw2.c
index 10690920e6fd..133aeeb969a6 100644
--- a/sys/netpfil/ipfw/ip_fw2.c
+++ b/sys/netpfil/ipfw/ip_fw2.c
@@ -780,7 +780,9 @@ static int
flow6id_match(int curr_flow, ipfw_insn_u32 *cmd)
{
int i;
- for (i=0; i <= cmd->o.arg1; ++i)
+ /* Mask proto version and traffic class out before comparing flow-id */
+ curr_flow &= ntohl(IPV6_FLOWLABEL_MASK);
+ for (i=0; i < cmd->o.arg1; ++i)
if (curr_flow == cmd->d[i])
return 1;
return 0;
diff --git a/tests/sys/netpfil/common/pft_ping.py b/tests/sys/netpfil/common/pft_ping.py
index a2a1d9c7f4ec..ada4f8607ab0 100644
--- a/tests/sys/netpfil/common/pft_ping.py
+++ b/tests/sys/netpfil/common/pft_ping.py
@@ -63,6 +63,7 @@ def prepare_ipv6(send_params):
dst_address = send_params.get('dst_address')
hlim = send_params.get('hlim')
tc = send_params.get('tc')
+ fl = send_params.get('fl')
ip6 = sp.IPv6(dst=dst_address)
if src_address:
ip6.src = src_address
@@ -70,6 +71,8 @@ def prepare_ipv6(send_params):
ip6.hlim = hlim
if tc:
ip6.tc = tc
+ if fl:
+ ip6.fl = fl
return ip6
@@ -224,6 +227,7 @@ def check_ipv6(expect_params, packet):
flags = expect_params.get('flags')
hlim = expect_params.get('hlim')
tc = expect_params.get('tc')
+ fl = expect_params.get('fl')
ip6 = packet.getlayer(sp.IPv6)
if not ip6:
LOGGER.debug('Packet is not IPv6!')
@@ -245,6 +249,9 @@ def check_ipv6(expect_params, packet):
if tc and ip6.tc != tc:
LOGGER.debug(f'Wrong TC value {ip6.tc}, expected {tc}')
return False
+ if fl and ip6.fl != fl:
+ LOGGER.debug(f'Wrong Flow Label value {ip6.fl}, expected {fl}')
+ return False
return True
@@ -635,6 +642,8 @@ def parse_args():
help='ICMP Echo Request payload size')
parser_send.add_argument('--send-tc', type=int,
help='IPv6 Traffic Class or IPv4 DiffServ / ToS')
+ parser_send.add_argument('--send-fl', type=int,
+ help='IPv6 Flow label')
parser_send.add_argument('--send-tcpopt-unaligned', action='store_true',
help='Include unaligned TCP options')
parser_send.add_argument('--send-nop', action='store_true',
@@ -652,6 +661,8 @@ def parse_args():
help='TCP sequence number')
parser_expect.add_argument('--expect-tc', type=int,
help='IPv6 Traffic Class or IPv4 DiffServ / ToS')
+ parser_expect.add_argument('--expect-fl', type=int,
+ help='IPv6 Flow Label')
parser.add_argument('-v', '--verbose', action='store_true',
help=('Enable verbose logging. Apart of potentially useful information '
@@ -673,7 +684,7 @@ def main():
send_params = {}
expect_params = {}
for param_name in (
- 'flags', 'hlim', 'length', 'mss', 'seq', 'tc', 'frag_length',
+ 'flags', 'hlim', 'length', 'mss', 'seq', 'tc', 'fl', 'frag_length',
'sport', 'dport',
):
param_arg = vars(args).get(f'send_{param_name}')
diff --git a/tests/sys/netpfil/ipfw/Makefile b/tests/sys/netpfil/ipfw/Makefile
index 52f898050267..0be870945891 100644
--- a/tests/sys/netpfil/ipfw/Makefile
+++ b/tests/sys/netpfil/ipfw/Makefile
@@ -4,6 +4,7 @@ TESTSDIR= ${TESTSBASE}/sys/netpfil/ipfw
ATF_TESTS_SH+= fwd \
divert \
+ ipv6-flow-id \
log \
lookup \
table
diff --git a/tests/sys/netpfil/ipfw/ipv6-flow-id.sh b/tests/sys/netpfil/ipfw/ipv6-flow-id.sh
new file mode 100644
index 000000000000..fd3ef2f6cd81
--- /dev/null
+++ b/tests/sys/netpfil/ipfw/ipv6-flow-id.sh
@@ -0,0 +1,78 @@
+#
+# Copyright (c) 2026 Boris Lytochkin
+#
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+common_dir="$(atf_get_srcdir)/../common"
+. ${common_dir}/utils.subr
+
+NC="nc -w 1 -dnN"
+
+setup_network_v6()
+{
+ epair="$1"
+
+ ifconfig ${epair}a inet6 2001:db8:42::1/64 up no_dad -ifdisabled
+
+ vnet_mkjail alcatraz ${epair}b
+
+ ifconfig -j alcatraz ${epair}b inet6 2001:db8:42::2/64 up no_dad -ifdisabled
+
+ jexec alcatraz /usr/sbin/inetd -p /dev/null $(atf_get_srcdir)/lookup_inetd.conf
+
+ # Sanity checks
+ atf_check -s exit:0 -o ignore ping6 -i .1 -c 3 -s 1200 2001:db8:42::2
+ atf_check -o "inline:GOOD 82\n" ${NC} 2001:db8:42::2 82
+}
+
+atf_test_case "ipv6fl" "cleanup"
+
+ipv6fl_head()
+{
+ atf_set descr 'flow-id test'
+ atf_set require.user root
+ atf_set require.progs python3 scapy
+}
+
+ipv6fl_body()
+{
+
+ firewall_init "ipfw"
+
+ epair=$(vnet_mkepair)
+
+ setup_network_v6 ${epair}
+
+ # Check if the firewall is able to match exact IPv6 flow label
+ firewall_config "alcatraz" ipfw ipfw \
+ "ipfw -q add 100 allow ip6 from any to any flow-id 0xbaad" \
+ "ipfw -q add 200 deny ipv6-icmp from any to any icmp6types 128 in"
+
+ # Check Flow Label matches
+ atf_check -s exit:0 ${common_dir}/pft_ping.py \
+ --sendif ${epair}a \
+ --fromaddr 2001:db8:42::1 \
+ --to 2001:db8:42::2 \
+ --send-fl $((0xbaad)) \
+ --replyif ${epair}a
+
+ # Check Flow Label mismatch
+ atf_check -s exit:1 ${common_dir}/pft_ping.py \
+ --sendif ${epair}a \
+ --fromaddr 2001:db8:42::1 \
+ --to 2001:db8:42::2 \
+ --send-fl $((0xf001)) \
+ --replyif ${epair}a
+
+}
+
+ipv6fl_cleanup()
+{
+ firewall_cleanup $1
+}
+
+atf_init_test_cases()
+{
+ atf_add_test_case "ipv6fl"
+}