kernel/linux.git/net/ipv4/netfilter, branch v6.18.34

netfilter: x_tables: close dangling table module init race

2026-06-01T15:50:53+00:00

[ Upstream commit 16bc4b6686b2c112c10e67d6b493adc3607256d3 ] Similar to the previous ebtables patch: template add exposes the table to userspace, we must do this last to rnsure the pernet ops are set up (contain the destructors). Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: x_tables: add and use xtables_unregister_table_exit

2026-06-01T15:50:53+00:00

[ Upstream commit b4597d5fd7d2f8cebfffd40dffb5e003cc78964c ] Previous change added xtables_unregister_table_pre_exit to detach the table from the packetpath and to unlink it from the active table list. In case of rmmod, userspace that is doing set/getsockopt for this table will not be able to re-instantiate the table: 1. The larval table has been removed already 2. existing instantiated table is no longer on the xt pernet table list. This adds the second stage helper: unlink the table from the dying list, free the hook ops (if any) and do the audit notification. It replaces xt_unregister_table(). Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Reported-by: Tristan Madani Reviewed-by: Tristan Madani Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: x_tables: add and use xt_unregister_table_pre_exit

2026-06-01T15:50:53+00:00

[ Upstream commit 527d6931473b75d90e38942aae6537d1a527f1fd ] Remove the copypasted variants of _pre_exit and add one single function in the xtables core. ebtables is not compatible with x_tables and therefore unchanged. This is a preparation patch to reduce noise in the followup bug fixes. Reviewed-by: Tristan Madani Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Stable-dep-of: b4597d5fd7d2 ("netfilter: x_tables: add and use xtables_unregister_table_exit") Signed-off-by: Sasha Levin

netfilter: x_tables: unregister the templates first

2026-06-01T15:50:53+00:00

[ Upstream commit d338693d778579b676a61346849bebd892427158 ] When the module is going away we need to zap the template first. Else there is a small race window where userspace could instantiate a new table after the pernet exit function has removed the current table. Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default") Reported-by: Tristan Madani Reviewed-by: Tristan Madani Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/ Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: arp_tables: fix IEEE1394 ARP payload parsing

2026-05-23T11:07:07+00:00

[ Upstream commit 1e8e3f449b1e73b73a843257635b9c50f0cc0f0a ] Weiming Shi says: "arp_packet_match() unconditionally parses the ARP payload assuming two hardware addresses are present (source and target). However, IPv4-over-IEEE1394 ARP (RFC 2734) omits the target hardware address field, and arp_hdr_len() already accounts for this by returning a shorter length for ARPHRD_IEEE1394 devices. As a result, on IEEE1394 interfaces arp_packet_match() advances past a nonexistent target hardware address and reads the wrong bytes for both the target device address comparison and the target IP address. This causes arptables rules to match against garbage data, leading to incorrect filtering decisions: packets that should be accepted may be dropped and vice versa. The ARP stack in net/ipv4/arp.c (arp_create and arp_process) already handles this correctly by skipping the target hardware address for ARPHRD_IEEE1394. Apply the same pattern to arp_packet_match()." Mangle the original patch to always return 0 (no match) in case user matches on the target hardware address which is never present in IEEE1394. Note that this returns 0 (no match) for either normal and inverse match because matching in the target hardware address in ARPHRD_IEEE1394 has never been supported by arptables. This is intentional, matching on the target hardware address should never evaluate true for ARPHRD_IEEE1394. Moreover, adjust arpt_mangle to drop the packet too as AI suggests: In arpt_mangle, the logic assumes a standard ARP layout. Because IEEE1394 (FireWire) omits the target hardware address, the linear pointer arithmetic miscalculates the offset for the target IP address. This causes mangling operations to write to the wrong location, leading to packet corruption. To ensure safety, this patch drops packets (NF_DROP) when mangling is requested for these fields on IEEE1394 devices, as the current implementation cannot correctly map the FireWire ARP payload. This omits both mangling target hardware and IP address. Even if IP address mangling should be possible in IEEE1394, this would require to adjust arpt_mangle offset calculation, which has never been supported. Based on patch from Weiming Shi . Fixes: 6752c8db8e0c ("firewire net, ipv4 arp: Extend hardware address and remove driver-level packet inspection.") Reported-by: Xiang Mei Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nat: use kfree_rcu to release ops

2026-05-23T11:07:02+00:00

[ Upstream commit 6eda0d771f94267f73f57c94630aa47e90957915 ] Florian Westphal says: "Historically this is not an issue, even for normal base hooks: the data path doesn't use the original nf_hook_ops that are used to register the callbacks. However, in v5.14 I added the ability to dump the active netfilter hooks from userspace. This code will peek back into the nf_hook_ops that are available at the tail of the pointer-array blob used by the datapath. The nat hooks are special, because they are called indirectly from the central nat dispatcher hook. They are currently invisible to the nfnl hook dump subsystem though. But once that changes the nat ops structures have to be deferred too." Update nf_nat_register_fn() to deal with partial exposition of the hooks from error path which can be also an issue for nfnetlink_hook. Fixes: e2cf17d3774c ("netfilter: add new hook nfnl subsystem") Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: nf_reject: don't reply to icmp error messages

2025-09-11T13:40:55+00:00

tcp reject code won't reply to a tcp reset. But the icmp reject 'netdev' family versions will reply to icmp dst-unreach errors, unlike icmp_send() and icmp6_send() which are used by the inet family implementation (and internally by the REJECT target). Check for the icmp(6) type and do not respond if its an unreachable error. Without this, something like 'ip protocol icmp reject', when used in a netdev chain attached to 'lo', cause a packet loop. Same for two hosts that both use such a rule: each error packet will be replied to. Such situation persist until the (bogus) rule is amended to ratelimit or checks the icmp type before the reject statement. As the inet versions don't do this make the netdev ones follow along. Signed-off-by: Florian Westphal

netfilter: nf_reject: remove unneeded exports

2025-09-02T13:28:17+00:00

These functions have no external callers and can be static. Signed-off-by: Florian Westphal

ipv4: Convert ->flowi4_tos to dscp_t.

2025-08-27T00:34:31+00:00

Convert the ->flowic_tos field of struct flowi_common from __u8 to dscp_t, rename it ->flowic_dscp and propagate these changes to struct flowi and struct flowi4. We've had several bugs in the past where ECN bits could interfere with IPv4 routing, because these bits were not properly cleared when setting ->flowi4_tos. These bugs should be fixed now and the dscp_t type has been introduced to ensure that variables carrying DSCP values don't accidentally have any ECN bits set. Several variables and structure fields have been converted to dscp_t already, but the main IPv4 routing structure, struct flowi4, is still using a __u8. To avoid any future regression, this patch converts it to dscp_t. There are many users to convert at once. Fortunately, around half of ->flowi4_tos users already have a dscp_t value at hand, which they currently convert to __u8 using inet_dscp_to_dsfield(). For all of these users, we just need to drop that conversion. But, although we try to do the __u8 <-> dscp_t conversions at the boundaries of the network or of user space, some places still store TOS/DSCP variables as __u8 in core networking code. Those can hardly be converted either because the data structure is part of UAPI or because the same variable or field is also used for handling ECN in other parts of the code. In all of these cases where we don't have a dscp_t variable at hand, we need to use inet_dsfield_to_dscp() when interacting with ->flowi4_dscp. Changes since v1: * Fix space alignment in __bpf_redirect_neigh_v4() (Ido). Signed-off-by: Guillaume Nault Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/29acecb45e911d17446b9a3dbdb1ab7b821ea371.1756128932.git.gnault@redhat.com Signed-off-by: Jakub Kicinski

tcp: Don't pass hashinfo to socket lookup helpers.

2025-08-26T00:53:35+00:00

These socket lookup functions required struct inet_hashinfo because they are shared by TCP and DCCP. * __inet_lookup_established() * __inet_lookup_listener() * __inet6_lookup_established() * inet6_lookup_listener() DCCP has gone, and we don't need to pass hashinfo down to them. Let's fetch net->ipv4.tcp_death_row.hashinfo directly in the above 4 functions. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250822190803.540788-5-kuniyu@google.com Signed-off-by: Jakub Kicinski