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

netfilter: bridge: eb_tables: close module init race

2026-06-01T15:50:54+00:00

[ Upstream commit 27414ff1b287ea9a2a11675149ec28e05539f3cc ] sashiko reports for unrelated patch: Does the core ebtables initialization in ebtables.c suffer from a similar race? Once nf_register_sockopt() completes, the sockopts are exposed globally. sockopt has to be registered last, just like in ip/ip6/arptables. Fixes: 5b53951cfc85 ("netfilter: ebtables: use net_generic infra") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: close dangling table module init race

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

[ Upstream commit 92c603fa07bc0d6a17345de3ad7954730b8de44b ] sashiko reported for a related patch: In modules like iptable_raw.c, [..], if register_pernet_subsys() fails, the rollback might call kfree(rawtable_ops) before [..] During this window, could a concurrent userspace process find the globally visible template, trigger table_init(), [..] The table init functions must always register the template last. Otherwise, set/getsockopt can instantiate a table in a namespace while the required pernet ops (contain the destructor) isn't available. This change is also required in x_tables, handled in followup change. Fixes: 87663c39f898 ("netfilter: ebtables: do not hook tables by default") Reviewed-by: Tristan Madani Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: move to two-stage removal scheme

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

[ Upstream commit b7f0544d86d439cb946515d2ef6a0a75e8626710 ] Like previous patches for x_tables, follow same pattern in ebtables. We can't reuse xt helpers: ebt_table struct layout is incompatible. table->ops assignment is now done while still holding the ebt mutex to make sure we never expose partially-filled table struct. Fixes: 87663c39f898 ("netfilter: ebtables: do not hook tables by default") Reviewed-by: Tristan Madani Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: replace -EEXIST with -EBUSY

2026-02-11T12:41:49+00:00

[ Upstream commit 2bafeb8d2f380c3a81d98bd7b78b854b564f9cd4 ] The -EEXIST error code is reserved by the module loading infrastructure to indicate that a module is already loaded. When a module's init function returns -EEXIST, userspace tools like kmod interpret this as "module already loaded" and treat the operation as successful, returning 0 to the user even though the module initialization actually failed. Replace -EEXIST with -EBUSY to ensure correct error reporting in the module initialization path. Affected modules: * ebtable_broute ebtable_filter ebtable_nat arptable_filter * ip6table_filter ip6table_mangle ip6table_nat ip6table_raw * ip6table_security iptable_filter iptable_mangle iptable_nat * iptable_raw iptable_security Signed-off-by: Daniel Gomez Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support

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

Expose the input bridge interface ethernet address so it can be used to redirect the packet to the receiving physical device for processing. Tested with nft command line tool. table bridge nat { chain PREROUTING { type filter hook prerouting priority 0; policy accept; ether daddr de:ad:00:00:be:ef meta pkttype set host ether daddr set meta ibrhwdr accept } } Joint work with Pablo Neira. Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal

netfilter: ebtables: Use vmalloc_array() to improve code

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

Remove array_size() calls and replace vmalloc() with vmalloc_array() to simplify the code. vmalloc_array() is also optimized better, uses fewer instructions, and handles overflow more concisely[1]. [1]: https://lore.kernel.org/lkml/abc66ec5-85a4-47e1-9759-2f60ab111971@vivo.com/ Signed-off-by: Qianfeng Rong Signed-off-by: Florian Westphal

netfilter: add back NETFILTER_XTABLES dependencies

2025-08-07T11:19:25+00:00

Some Kconfig symbols were changed to depend on the 'bool' symbol NETFILTER_XTABLES_LEGACY, which means they can now be set to built-in when the xtables code itself is in a loadable module: x86_64-linux-ld: vmlinux.o: in function `arpt_unregister_table_pre_exit': (.text+0x1831987): undefined reference to `xt_find_table' x86_64-linux-ld: vmlinux.o: in function `get_info.constprop.0': arp_tables.c:(.text+0x1831aab): undefined reference to `xt_request_find_table_lock' x86_64-linux-ld: arp_tables.c:(.text+0x1831bea): undefined reference to `xt_table_unlock' x86_64-linux-ld: vmlinux.o: in function `do_arpt_get_ctl': arp_tables.c:(.text+0x183205d): undefined reference to `xt_find_table_lock' x86_64-linux-ld: arp_tables.c:(.text+0x18320c1): undefined reference to `xt_table_unlock' x86_64-linux-ld: arp_tables.c:(.text+0x183219a): undefined reference to `xt_recseq' Change these to depend on both NETFILTER_XTABLES and NETFILTER_XTABLES_LEGACY. Fixes: 9fce66583f06 ("netfilter: Exclude LEGACY TABLES on PREEMPT_RT.") Signed-off-by: Arnd Bergmann Acked-by: Florian Westphal Tested-by: Breno Leitao Signed-off-by: Pablo Neira Ayuso

netfilter: Exclude LEGACY TABLES on PREEMPT_RT.

2025-07-25T16:38:50+00:00

The seqcount xt_recseq is used to synchronize the replacement of xt_table::private in xt_replace_table() against all readers such as ipt_do_table() To ensure that there is only one writer, the writing side disables bottom halves. The sequence counter can be acquired recursively. Only the first invocation modifies the sequence counter (signaling that a writer is in progress) while the following (recursive) writer does not modify the counter. The lack of a proper locking mechanism for the sequence counter can lead to live lock on PREEMPT_RT if the high prior reader preempts the writer. Additionally if the per-CPU lock on PREEMPT_RT is removed from local_bh_disable() then there is no synchronisation for the per-CPU sequence counter. The affected code is "just" the legacy netfilter code which is replaced by "netfilter tables". That code can be disabled without sacrificing functionality because everything is provided by the newer implementation. This will only requires the usage of the "-nft" tools instead of the "-legacy" ones. The long term plan is to remove the legacy code so lets accelerate the progress. Relax dependencies on iptables legacy, replace select with depends on, this should cause no harm to existing kernel configs and users can still toggle IP{6}_NF_IPTABLES_LEGACY in any case. Make EBTABLES_LEGACY, IPTABLES_LEGACY and ARPTABLES depend on NETFILTER_XTABLES_LEGACY. Hide xt_recseq and its users, xt_register_table() and xt_percpu_counter_alloc() behind NETFILTER_XTABLES_LEGACY. Let NETFILTER_XTABLES_LEGACY depend on !PREEMPT_RT. This will break selftest expecing the legacy options enabled and will be addressed in a following patch. Co-developed-by: Florian Westphal Co-developed-by: Sebastian Andrzej Siewior Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Pablo Neira Ayuso

netfilter: bridge: Move specific fragmented packet to slow_path instead of dropping it

2025-05-05T11:13:08+00:00

The config NF_CONNTRACK_BRIDGE will change the bridge forwarding for fragmented packets. The original bridge does not know that it is a fragmented packet and forwards it directly, after NF_CONNTRACK_BRIDGE is enabled, function nf_br_ip_fragment and br_ip6_fragment will check the headroom. In original br_forward, insufficient headroom of skb may indeed exist, but there's still a way to save the skb in the device driver after dev_queue_xmit.So droping the skb will change the original bridge forwarding in some cases. Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system") Signed-off-by: Huajian Yang Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: replace deprecated strncpy with strscpy_pad

2024-10-15T15:29:51+00:00

strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. In this particular instance, the usage of strncpy() is fine and works as expected. However, towards the goal of [2], we should consider replacing it with an alternative as many instances of strncpy() are bug-prone. Its removal from the kernel promotes better long term health for the codebase. The current usage of strncpy() likely just wants the NUL-padding behavior offered by strncpy() and doesn't care about the NUL-termination. Since the compiler doesn't know the size of @dest, we can't use strtomem_pad(). Instead, use strscpy_pad() which behaves functionally the same as strncpy() in this context -- as we expect br_dev->name to be NUL-terminated itself. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 [2] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html Cc: Kees Cook Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt Reviewed-by: Simon Horman Signed-off-by: Pablo Neira Ayuso