kernel/linux.git/net/netfilter/ipvs, branch v6.18.40

ipvs: reload ip header after head reallocation

2026-07-24T14:17:18+00:00

commit a2f57827bf7c695b8c72dc4511cae8e86582369d upstream. __ip_vs_get_out_rt() calls skb_ensure_writable() which may reallocate skb->head. Fixes: 8d8e20e2d7bb ("ipvs: Decrement ttl") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-sonnet-4-6 Acked-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

ipvs: fix more places with wrong ipv6 transport offsets

2026-07-24T14:17:18+00:00

commit b3fe4cbd583895987935a9bdad01c8f9d3a02310 upstream. Sashiko reports for more incorrect IPv6 transport offsets. The app code for TCP was assuming IPv4 network header even after the ipvsh argument was provided. This can cause problems with apps over IPv6. As for the only official app in the kernel tree (FTP) this problem is harmless because we use Netfilter to mangle the FTP ports and we do not adjust the TCP seq numbers. Also, provide correct offset of the ICMPV6 header in ip_vs_out_icmp_v6() for correct checksum checks when the IPv6 packet has extension headers. Fixes: d12e12299a69 ("ipvs: add ipv6 support to ftp") Fixes: 2a3b791e6e11 ("IPVS: Add/adjust Netfilter hook functions and helpers for v6") Cc: stable@vger.kernel.org Link: https://sashiko.dev/#/patchset/20260706101624.69471-1-zhaoyz24%40mails.tsinghua.edu.cn Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

ipvs: reset full ip_vs_seq structs in ip_vs_conn_new

2026-07-24T14:17:15+00:00

commit 2975324d164c552b028632f107b567302863b7f6 upstream. Commit 9a05475cebdd ("ipvs: avoid kmem_cache_zalloc in ip_vs_conn_new") changed ip_vs_conn_new() to allocate an ip_vs_conn object with kmem_cache_alloc(). The function then initializes many fields explicitly, but only resets in_seq.delta and out_seq.delta in the two struct ip_vs_seq members. That leaves init_seq and previous_delta uninitialized. This is normally harmless while the corresponding IP_VS_CONN_F_IN_SEQ or IP_VS_CONN_F_OUT_SEQ flag is clear. For connections learned from a sync message, however, ip_vs_proc_conn() preserves those flags from IP_VS_CONN_F_BACKUP_MASK and passes opt=NULL when the message omits IPVS_OPT_SEQ_DATA. In that case the new connection can be hashed with SEQ flags set but with the rest of in_seq/out_seq still containing stale slab data. When a packet for such a connection is later handled by an IPVS application helper, vs_fix_seq() and vs_fix_ack_seq() use previous_delta and init_seq to rewrite TCP sequence numbers. A malformed sync message can therefore make forwarded packets carry stale slab bytes in their TCP seq/ack numbers, and can also corrupt the forwarded TCP flow. Reset both struct ip_vs_seq members completely before publishing the connection. This matches the existing "reset struct ip_vs_seq" comment and keeps the sequence-adjustment gates inactive unless valid sequence data is installed later. Fixes: 9a05475cebdd ("ipvs: avoid kmem_cache_zalloc in ip_vs_conn_new") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Yizhou Zhao Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

ipvs: use parsed transport offset in SCTP state lookup

2026-07-24T14:17:15+00:00

commit 2f75c0faa3361b28e36cc0512b3299e163e25789 upstream. set_sctp_state() reads the SCTP chunk header again in order to drive the IPVS SCTP state table. For IPv6 it computes the offset with sizeof(struct ipv6hdr), while the surrounding IPVS code uses iph.len from ip_vs_fill_iph_skb(), where ipv6_find_hdr() has already skipped extension headers and found the real transport header. This makes the state machine read from the wrong offset for IPv6 SCTP packets that carry extension headers. For example, an INIT packet with an 8-byte destination options header can be scheduled correctly by sctp_conn_schedule(), but set_sctp_state() reads the first byte of the SCTP verification tag as a DATA chunk type. The connection then moves from NONE to ESTABLISHED instead of INIT1, gets the longer established timeout, and updates the active/inactive destination counters incorrectly. This happens even though the SCTP handshake has not completed. Use the parsed transport offset passed down from ip_vs_set_state() for the SCTP chunk-header lookup. For IPv4 and IPv6 packets without extension headers this preserves the existing offset. Fixes: 2906f66a5682 ("ipvs: SCTP Trasport Loadbalancing Support") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/netdev/20260705123040.35755-1-zhaoyz24@mails.tsinghua.edu.cn/ Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude Code:GLM-5.2 Signed-off-by: Yizhou Zhao Acked-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Greg Kroah-Hartman

ipvs: ensure inner headers in ICMP errors are in headroom

2026-07-24T14:16:50+00:00

[ Upstream commit 3f7a535ff0fa627a0132803e4c2f903ceffcbc1c ] Sashiko points out that after stripping the outer headers with pskb_pull() we should ensure the inner IP headers in ICMP errors from tunnels are present in the skb headroom for functions like ipv4_update_pmtu(), icmp_send() and IP_VS_DBG(). Also, add more checks for the length of the inner headers. Fixes: f2edb9f7706d ("ipvs: implement passive PMTUD for IPIP packets") Link: https://sashiko.dev/#/patchset/20260702073430.67680-1-zhaoyz24%40mails.tsinghua.edu.cn Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

ipvs: fix PMTU for GUE/GRE tunnel ICMP errors

2026-07-24T14:16:50+00:00

[ Upstream commit 6b335af0d0d1ff44ac579d106953bf19299e5233 ] When an ICMP Fragmentation Needed error is received for a tunneled IPVS connection, ip_vs_in_icmp() recomputes the MTU that the original packet can use by subtracting the tunnel overhead from the reported next-hop MTU. The current code always subtracts sizeof(struct iphdr), which is only the IPIP overhead. For GUE and GRE tunnels, ipvs_udp_decap() and ipvs_gre_decap() already compute the additional tunnel header length, but that value is scoped to the decapsulation block and is lost before the ICMP_FRAG_NEEDED handling. As a result, the ICMP error sent back to the client advertises an MTU that is too large, so PMTUD can fail to converge for GUE/GRE-tunneled real servers. With a reported next-hop MTU of 1400, a GUE tunnel currently returns 1380 to the client. The correct value is 1368: 1400 - sizeof(struct iphdr) - sizeof(struct udphdr) - sizeof(struct guehdr) Hoist the tunnel header length into the main ip_vs_in_icmp() scope and subtract sizeof(struct iphdr) + ulen in the Fragmentation Needed path. The IPIP path keeps ulen as 0, so its existing 1400 - 20 = 1380 result is unchanged. Fixes: 508f744c0de3 ("ipvs: strip udp tunnel headers from icmp errors") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Yizhou Zhao Acked-by: Julian Anastasov Signed-off-by: Florian Westphal Stable-dep-of: 3f7a535ff0fa ("ipvs: ensure inner headers in ICMP errors are in headroom") Signed-off-by: Sasha Levin

ipvs: use parsed transport offset in TCP state lookup

2026-07-24T14:16:50+00:00

[ Upstream commit 2500fa3958b1ba51c2b065e39db1b04dfa7e23a2 ] TCP state handling reparses the skb to find the TCP header. For IPv6 it uses sizeof(struct ipv6hdr), while the surrounding IPVS code already parsed the packet with ip_vs_fill_iph_skb() and has the real transport-header offset in iph.len. This makes TCP state handling look at the wrong bytes when an IPv6 packet carries extension headers. Use the parsed transport offset passed down from ip_vs_set_state() when reading the TCP header. For IPv4 and for IPv6 packets without extension headers, the passed offset matches the previous value. Fixes: 0bbdd42b7efa6 ("IPVS: Extend protocol DNAT/SNAT and state handlers") Link: https://lore.kernel.org/netdev/20260705125659.37744-1-zhaoyz24@mails.tsinghua.edu.cn/ Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: Claude Code:GLM-5.2 Signed-off-by: Yizhou Zhao Acked-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

ipvs: pass parsed transport offset to state handlers

2026-07-24T14:16:50+00:00

[ Upstream commit bae7ce7bafb59e42dc0e0e2999fdd9d1cffe3866 ] IPVS callers already parse the packet into struct ip_vs_iphdr before updating connection state. For IPv6 this records the real transport-header offset after extension headers in iph.len. Pass this parsed transport offset through ip_vs_set_state() and the protocol state_transition() callback so protocol handlers can use the same packet context as scheduling and NAT handling. This patch only changes the common callback plumbing and adapts the protocol callback signatures; TCP and SCTP start using the value in follow-up patches. Signed-off-by: Yizhou Zhao Acked-by: Julian Anastasov Signed-off-by: Florian Westphal Stable-dep-of: 2500fa3958b1 ("ipvs: use parsed transport offset in TCP state lookup") Signed-off-by: Sasha Levin

ipvs: skip ipv6 extension headers for csum checks

2026-06-19T11:44:15+00:00

commit 05cfe9863ef049d98141dc2969eefde72fb07625 upstream. Protocol checksum validation fails for IPv6 if there are extension headers before the protocol header. iph->len already contains its offset, so use it to fix the problem. Fixes: 2906f66a5682 ("ipvs: SCTP Trasport Loadbalancing Support") Fixes: 0bbdd42b7efa ("IPVS: Extend protocol DNAT/SNAT and state handlers") Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Nazar Kalashnikov Signed-off-by: Greg Kroah-Hartman

ipvs: clear the svc scheduler ptr early on edit

2026-06-19T11:43:52+00:00

[ Upstream commit 193989cc6d80dd8e0460fb3992e69fa03bf0ff9b ] ip_vs_edit_service() while unbinding the old scheduler clears the svc->scheduler ptr after the scheduler module initiates RCU callbacks. This can cause packets to use the old scheduler at the time when svc->sched_data is already freed after RCU grace period. Fix it by clearing the ptr early in ip_vs_unbind_scheduler(), before the done_service method schedules any RCU callbacks. Also, if the new scheduler fails to initialize when replacing the old scheduler, try to restore the old scheduler while still returning the error code. Link: https://sashiko.dev/#/patchset/20260519015506.634185-1-rosenp%40gmail.com Fixes: 05f00505a89a ("ipvs: fix crash if scheduler is changed") Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin