kernel/linux.git/tools/testing/selftests/net, branch master

selftests/net: packetdrill: cover RFC 5961 5.2 challenge ACK on both edges

2026-04-23T18:04:01+00:00

RFC 5961 Section 5.2 / RFC 793 Section 3.9 require a challenge ACK whenever an incoming SEG.ACK falls outside [SND.UNA - MAX.SND.WND, SND.NXT]. There is currently no packetdrill coverage for either edge. Add tcp_rfc5961_ack-out-of-window.pkt, which in a single passive-open connection exercises: - Upper edge (SEG.ACK > SND.NXT): peer ACKs data that was never sent before the server has transmitted anything. - Lower edge (SEG.ACK < SND.UNA - MAX.SND.WND): after the server has sent 2000 bytes (the peer-advertised rwnd forces two 1000-byte segments, both acknowledged), peer sends an ACK that is older than the acceptable window. Both cases must elicit a challenge ACK . The per-socket RFC 5961 Section 7 rate limit is disabled for the duration of the test so that both challenge ACKs can fire back-to-back. Signed-off-by: Jiayuan Chen Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260422123605.320000-3-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski

tcp: send a challenge ACK on SEG.ACK > SND.NXT

2026-04-23T18:04:00+00:00

RFC 5961 Section 5.2 validates an incoming segment's ACK value against the range [SND.UNA - MAX.SND.WND, SND.NXT] and states: "All incoming segments whose ACK value doesn't satisfy the above condition MUST be discarded and an ACK sent back." Commit 354e4aa391ed ("tcp: RFC 5961 5.2 Blind Data Injection Attack Mitigation") opted Linux into this mitigation and implements the challenge ACK on the lower side (SEG.ACK < SND.UNA - MAX.SND.WND), but the symmetric upper side (SEG.ACK > SND.NXT) still takes the pre-RFC-5961 path and silently returns SKB_DROP_REASON_TCP_ACK_UNSENT_DATA, even though RFC 793 Section 3.9 (now RFC 9293 Section 3.10.7.4) has always required: "If the ACK acknowledges something not yet sent (SEG.ACK > SND.NXT) then send an ACK, drop the segment, and return." Complete the mitigation by sending a challenge ACK on that branch, reusing the existing tcp_send_challenge_ack() path which already enforces the per-socket RFC 5961 Section 7 rate limit via __tcp_oow_rate_limited(). FLAG_NO_CHALLENGE_ACK is honoured for symmetry with the lower-edge case. Update the existing tcp_ts_recent_invalid_ack.pkt selftest, which drives this exact path, to consume the new challenge ACK. Fixes: 354e4aa391ed ("tcp: RFC 5961 5.2 Blind Data Injection Attack Mitigation") Signed-off-by: Jiayuan Chen Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260422123605.320000-2-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski

selftests: mptcp: add a check for sndbuf of S/C

2026-04-23T11:20:17+00:00

Add a new chk_sndbuf() helper to diag.sh that extracts the sndbuf (the 'tb' field from 'ss -m' skmem output) for both server and client MPTCP sockets, and verifies they are equal. Without the previous patch, it will fail: ''' 07 ....chk sndbuf server/client [FAIL] sndbuf S=20480 != C=2630656 ''' Signed-off-by: Gang Yan Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260420-net-mptcp-sync-sndbuf-accept-v1-2-e3523e3aeb44@kernel.org Signed-off-by: Paolo Abeni

selftests: net: add team_bridge_macvlan rx_mode test

2026-04-21T10:50:25+00:00

Add a test that exercises the ndo_change_rx_flags path through a macvlan -> bridge -> team -> dummy stack. This triggers dev_uc_add under addr_list_lock which flips promiscuity on the lower device. With the new work queue approach, this must not deadlock. Link: https://lore.kernel.org/netdev/20260214033859.43857-1-jiayuan.chen@linux.dev/ Reviewed-by: Breno Leitao Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20260416185712.2155425-15-sdf@fomichev.me Signed-off-by: Paolo Abeni

selftests: ovpn: serialize YNL listener startup

2026-04-17T08:54:04+00:00

Starting one background YNL notification listener per peer back-to-back can intermittently stall the test setup before the listeners even reach the Python main function. This was reproducible in a reduced test.sh setup-only loop: a single listener stayed stable across repeated runs, while starting listeners for all peers could hang early in the listener launch phase. Adding a short delay between listener launches makes the listeners start cleanly and eliminates the reproduced hangs in repeated normal and slow-runner tests. Serialize listener startup with a small sleep between setup_listener calls. Fixes: 77de28cd7cf1 ("selftests: ovpn: add notification parsing and matching") Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli

selftests: ovpn: align command flow with TAP

2026-04-17T08:54:03+00:00

Current tests do not properly adhere to the TAP infrastructure therefore they do not properly report failures leading to hangs of the CI machinery. Restructure ovpn selftests into using the TAP infrastructure: split each test in stages, execute stage bodies with fail-fast semantics, and emit KTAP pass/fail for each stage. Centralize behavior control in common.sh and makes the scripts use dedicated wrappers for required-success, expected-failure, and non-fatal commands. Also add the OVPN_VERBOSE mode that exposes captured command output for debugging. This way tests won't hang anymore in case of failure when executed within the CI machinery. This change also makes default OVPN_CLI and YNL resolution independent from the caller CWD by anchoring both to COMMON_DIR, so behavior is stable across direct execution and run_tests-style execution. Fixes: 959bc330a439 ("testing/selftests: add test tool and scripts for ovpn module") Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli

selftests: ovpn: add prefix to helpers and shared variables

2026-04-17T08:54:03+00:00

Current naming for shared variables, helpers and netnamespaces is a bit unfortunate as it doesn't come with a clean prefix. This showed to be problematic in case of name clashes with external scripts or in case of abrupt test termination (hanging netns' weren't easily reconducible to ovpn). Rename common helper entry points and all shared globals in the ovpn selftests to ovpn_ or OVPN_ names so test scripts and wrappers use a single explicit prefix. Also rename the temporary network namespaces created by the tests from peerN to ovpn_peerN. This makes leaked namespaces easier to identify. This is a mechanical refactor only, behavior is unchanged. Fixes: 959bc330a439 ("testing/selftests: add test tool and scripts for ovpn module") Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli

selftests: ovpn: flatten slurped notification JSON before filtering

2026-04-17T08:54:03+00:00

Notification comparison uses jq -s, which slurps all inputs into an array. Some inputs can be arrays themselves, and applying the .msg.peer filter directly on those entries triggers jq type errors. Expand any array-valued JSON items returned by jq -s before selecting .msg.peer, so the filter handles both normal notification objects and [] entries without type errors. Fixes: 77de28cd7cf1 ("selftests: ovpn: add notification parsing and matching") Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli

selftests: ovpn: fail notification check on mismatch

2026-04-17T08:54:03+00:00

compare_ntfs doesn't fail when expected and received notification streams diverge. Fix this bug by tracking the diff exit status explicitly and return it to the caller so notification mismatches propagate as test failures. Fixes: 77de28cd7cf1 ("selftests: ovpn: add notification parsing and matching") Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli

selftests: ovpn: add nftables config dependencies for test-mark

2026-04-17T08:54:03+00:00

test-mark.sh installs nftables rules in an inet/filter output chain and verifies packet drops via nft counters. In vmksft this can fail when the nftables core is not enabled by the ovpn selftest config. Add the missing kernel options required by this test: - CONFIG_NETFILTER - CONFIG_NF_TABLES - CONFIG_NF_TABLES_INET Fixes: 7b80d8a33500 ("selftests: ovpn: add test for the FW mark feature") Reported-by: Jakub Kicinski Closes: https://lore.kernel.org/all/20260319124114.42f91f72@kernel.org/ Signed-off-by: Ralf Lici Signed-off-by: Antonio Quartulli