kernel/linux.git/include/net/inet_connection_sock.h, branch v6.18.22

tcp: fix potential race in tcp_v6_syn_recv_sock()

2026-03-04T12:20:44+00:00

[ Upstream commit 858d2a4f67ff69e645a43487ef7ea7f28f06deae ] Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+937b5bbb6a815b3e5d0b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69949275.050a0220.2eeac1.0145.GAE@google.com/ Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260217161205.2079883-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: Update bind bucket state on port release

2025-09-23T08:12:15+00:00

Today, once an inet_bind_bucket enters a state where fastreuse >= 0 or fastreuseport >= 0 after a socket is explicitly bound to a port, it remains in that state until all sockets are removed and the bucket is destroyed. In this state, the bucket is skipped during ephemeral port selection in connect(). For applications using a reduced ephemeral port range (IP_LOCAL_PORT_RANGE socket option), this can cause faster port exhaustion since blocked buckets are excluded from reuse. The reason the bucket state isn't updated on port release is unclear. Possibly a performance trade-off to avoid scanning bucket owners, or just an oversight. Fix it by recalculating the bucket state when a socket releases a port. To limit overhead, each inet_bind2_bucket stores its own (fastreuse, fastreuseport) state. On port release, only the relevant port-addr bucket is scanned, and the overall state is derived from these. Signed-off-by: Jakub Sitnicki Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250917-update-bind-bucket-state-on-unhash-v5-1-57168b661b47@cloudflare.com Signed-off-by: Paolo Abeni

tcp: Remove sk->sk_prot->orphan_count.

2025-09-01T19:52:09+00:00

TCP tracks the number of orphaned (SOCK_DEAD but not yet destructed) sockets in tcp_orphan_count. In some code that was shared with DCCP, tcp_orphan_count is referenced via sk->sk_prot->orphan_count. Let's reference tcp_orphan_count directly. inet_csk_prepare_for_destroy_sock() is moved to inet_connection_sock.c due to header dependency. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Jason Xing Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250829215641.711664-1-kuniyu@google.com Signed-off-by: Jakub Kicinski

tcp/dccp: remove icsk->icsk_ack.timeout

2025-03-25T17:34:33+00:00

icsk->icsk_ack.timeout can be replaced by icsk->csk_delack_timer.expires This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250324203607.703850-3-edumazet@google.com Signed-off-by: Jakub Kicinski

tcp/dccp: remove icsk->icsk_timeout

2025-03-25T17:34:33+00:00

icsk->icsk_timeout can be replaced by icsk->icsk_retransmit_timer.expires This saves 8 bytes in TCP/DCCP sockets and helps for better cache locality. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250324203607.703850-2-edumazet@google.com Signed-off-by: Jakub Kicinski

tcp/dccp: Remove inet_connection_sock_af_ops.addr2sockaddr().

2025-03-24T19:10:13+00:00

inet_connection_sock_af_ops.addr2sockaddr() hasn't been used at all in the git era. $ git grep addr2sockaddr $(git rev-list HEAD | tail -n 1) Let's remove it. Note that there was a 4 bytes hole after sockaddr_len and now it's 6 bytes, so the binary layout is not changed. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250318060112.3729-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski

tcp: move icsk_clean_acked to a better location

2025-03-24T16:55:18+00:00

As a followup of my presentation in Zagreb for netdev 0x19: icsk_clean_acked is only used by TCP when/if CONFIG_TLS_DEVICE is enabled from tcp_ack(). Rename it to tcp_clean_acked, move it to tcp_sock structure in the tcp_sock_read_rx for better cache locality in TCP fast path. Define this field only when CONFIG_TLS_DEVICE is enabled saving 8 bytes on configs not using it. Signed-off-by: Eric Dumazet Reviewed-by: Neal Cardwell Reviewed-by: Sabrina Dubroca Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250317085313.2023214-1-edumazet@google.com Signed-off-by: Jakub Kicinski

tcp: cache RTAX_QUICKACK metric in a hot cache line

2025-03-18T12:44:59+00:00

tcp_in_quickack_mode() is called from input path for small packets. It calls __sk_dst_get() which reads sk->sk_dst_cache which has been put in sock_read_tx group (for good reasons). Then dst_metric(dst, RTAX_QUICKACK) also needs extra cache line misses. Cache RTAX_QUICKACK in icsk->icsk_ack.dst_quick_ack to no longer pull these cache lines for the cases a delayed ACK is scheduled. After this patch TCP receive path does not longer access sock_read_tx group. Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Reviewed-by: Neal Cardwell Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250312083907.1931644-1-edumazet@google.com Signed-off-by: Paolo Abeni

tcp: add the ability to control max RTO

2025-02-11T12:08:00+00:00

Currently, TCP stack uses a constant (120 seconds) to limit the RTO value exponential growth. Some applications want to set a lower value. Add TCP_RTO_MAX_MS socket option to set a value (in ms) between 1 and 120 seconds. It is discouraged to change the socket rto max on a live socket, as it might lead to unexpected disconnects. Following patch is adding a netns sysctl to control the default value at socket creation time. Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Reviewed-by: Neal Cardwell Reviewed-by: Kuniyuki Iwashima Signed-off-by: Paolo Abeni

tcp: rename inet_csk_{delete|reset}_keepalive_timer()

2025-02-07T19:53:27+00:00

inet_csk_delete_keepalive_timer() and inet_csk_reset_keepalive_timer() are only used from core TCP, there is no need to export them. Replace their prefix by tcp. Move them to net/ipv4/tcp_timer.c and make tcp_delete_keepalive_timer() static. Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Reviewed-by: Joe Damato Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250206094605.2694118-1-edumazet@google.com Signed-off-by: Jakub Kicinski