kernel/linux.git/include/linux/netfilter.h, branch v6.19.11

netfilter: nfnetlink_hook: Dump flowtable info

2025-07-25T16:40:01+00:00

Introduce NFNL_HOOK_TYPE_NFT_FLOWTABLE to distinguish flowtable hooks from base chain ones. Nested attributes are shared with the old NFTABLES hook info type since they fit apart from their misleading name. Old nftables in user space will ignore this new hook type and thus continue to print flowtable hooks just like before, e.g.: | family netdev { | hook ingress device test0 { | 0000000000 nf_flow_offload_ip_hook [nf_flow_table] | } | } With this patch in place and support for the new hook info type, output becomes more useful: | family netdev { | hook ingress device test0 { | 0000000000 flowtable ip mytable myft [nf_flow_table] | } | } Suggested-by: Florian Westphal Signed-off-by: Phil Sutter Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: Have a list of nf_hook_ops in nft_hook

2025-05-23T11:57:13+00:00

Supporting a 1:n relationship between nft_hook and nf_hook_ops is convenient since a chain's or flowtable's nft_hooks may remain in place despite matching interfaces disappearing. This stabilizes ruleset dumps in that regard and opens the possibility to claim newly added interfaces which match the spec. Also it prepares for wildcard interface specs since these will potentially match multiple interfaces. All spots dealing with hook registration are updated to handle a list of multiple nf_hook_ops, but nft_netdev_hook_alloc() only adds a single item for now to retain the old behaviour. The only expected functional change here is how vanishing interfaces are handled: Instead of dropping the respective nft_hook, only the matching nf_hook_ops are dropped. To safely remove individual ops from the list in netdev handlers, an rcu_head is added to struct nf_hook_ops so kfree_rcu() may be used. There is at least nft_flowtable_find_dev() which may be iterating through the list at the same time. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: make nf_conntrack_id callable without a module dependency

2025-05-23T11:57:12+00:00

While nf_conntrack_id() doesn't need any functionaliy from conntrack, it does reside in nf_conntrack_core.c -- callers add a module dependency on conntrack. Followup patch will need to compute the conntrack id from nf_tables_trace.c to include it in nf_trace messages emitted to userspace via netlink. I don't want to introduce a module dependency between nf_tables and conntrack for this. Since trace is slowpath, the added indirection is ok. One alternative is to move nf_conntrack_id to the netfilter/core.c, but I don't see a compelling reason so far. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_dup{4, 6}: Move duplication check to task_struct

2025-05-23T11:57:12+00:00

nf_skb_duplicated is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Due to the recursion involved, the simplest change is to make it a per-task variable. Move the per-CPU variable nf_skb_duplicated to task_struct and name it in_nf_duplicate. Add it to the existing bitfield so it doesn't use additional memory. Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Valentin Schneider Acked-by: Peter Zijlstra (Intel) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Pablo Neira Ayuso

netfilter: nfnetlink_queue: remove old clash resolution logic

2024-09-26T11:03:03+00:00

For historical reasons there are two clash resolution spots in netfilter, one in nfnetlink_queue and one in conntrack core. nfnetlink_queue one was added first: If a colliding entry is found, NAT NAT transformation is reversed by calling nat engine again with altered tuple. See commit 368982cd7d1b ("netfilter: nfnetlink_queue: resolve clash for unconfirmed conntracks") for details. One problem is that nf_reroute() won't take an action if the queueing doesn't occur in the OUTPUT hook, i.e. when queueing in forward or postrouting, packet will be sent via the wrong path. Another problem is that the scenario addressed (2nd UDP packet sent with identical addresses while first packet is still being processed) can also occur without any nfqueue involvement due to threaded resolvers doing A and AAAA requests back-to-back. This lead us to add clash resolution logic to the conntrack core, see commit 6a757c07e51f ("netfilter: conntrack: allow insertion of clashing entries"). Instead of fixing the nfqueue based logic, lets remove it and let conntrack core handle this instead. Retain the ->update hook for sake of nfqueue based conntrack helpers. We could axe this hook completely but we'd have to split confirm and helper logic again, see commit ee04805ff54a ("netfilter: conntrack: make conntrack userspace helpers work again"). This SHOULD NOT be backported to kernels earlier than v5.6; they lack adequate clash resolution handling. Patch was originally written by Pablo Neira Ayuso. Reported-by: Antonio Ojea Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1766 Signed-off-by: Florian Westphal Tested-by: Antonio Ojea Signed-off-by: Pablo Neira Ayuso

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2024-02-29T22:24:56+00:00

Cross-merge networking fixes after downstream PR. Conflicts: net/mptcp/protocol.c adf1bb78dab5 ("mptcp: fix snd_wnd initialization for passive socket") 9426ce476a70 ("mptcp: annotate lockless access for RX path fields") https://lore.kernel.org/all/20240228103048.19255709@canb.auug.org.au/ Adjacent changes: drivers/dpll/dpll_core.c 0d60d8df6f49 ("dpll: rely on rcu for netdev_dpll_pin()") e7f8df0e81bf ("dpll: move xa_erase() call in to match dpll_pin_alloc() error path order") drivers/net/veth.c 1ce7d306ea63 ("veth: try harder when allocating queue memory") 0bef512012b1 ("net: add netdev_lockdep_set_classes() to virtual drivers") drivers/net/wireless/intel/iwlwifi/mvm/d3.c 8c9bef26e98b ("wifi: iwlwifi: mvm: d3: implement suspend with MLO") 78f65fbf421a ("wifi: iwlwifi: mvm: ensure offloading TID queue exists") net/wireless/nl80211.c f78c1375339a ("wifi: nl80211: reject iftype change with mesh ID change") 414532d8aa89 ("wifi: cfg80211: use IEEE80211_MAX_MESH_ID_LEN appropriately") Signed-off-by: Jakub Kicinski

netfilter: bridge: confirm multicast packets before passing them up the stack

2024-02-28T23:22:44+00:00

conntrack nf_confirm logic cannot handle cloned skbs referencing the same nf_conn entry, which will happen for multicast (broadcast) frames on bridges. Example: macvlan0 | br0 / \ ethX ethY ethX (or Y) receives a L2 multicast or broadcast packet containing an IP packet, flow is not yet in conntrack table. 1. skb passes through bridge and fake-ip (br_netfilter)Prerouting. -> skb->_nfct now references a unconfirmed entry 2. skb is broad/mcast packet. bridge now passes clones out on each bridge interface. 3. skb gets passed up the stack. 4. In macvlan case, macvlan driver retains clone(s) of the mcast skb and schedules a work queue to send them out on the lower devices. The clone skb->_nfct is not a copy, it is the same entry as the original skb. The macvlan rx handler then returns RX_HANDLER_PASS. 5. Normal conntrack hooks (in NF_INET_LOCAL_IN) confirm the orig skb. The Macvlan broadcast worker and normal confirm path will race. This race will not happen if step 2 already confirmed a clone. In that case later steps perform skb_clone() with skb->_nfct already confirmed (in hash table). This works fine. But such confirmation won't happen when eb/ip/nftables rules dropped the packets before they reached the nf_confirm step in postrouting. Pablo points out that nf_conntrack_bridge doesn't allow use of stateful nat, so we can safely discard the nf_conn entry and let inet call conntrack again. This doesn't work for bridge netfilter: skb could have a nat transformation. Also bridge nf prevents re-invocation of inet prerouting via 'sabotage_in' hook. Work around this problem by explicit confirmation of the entry at LOCAL_IN time, before upper layer has a chance to clone the unconfirmed entry. The downside is that this disables NAT and conntrack helpers. Alternative fix would be to add locking to all code parts that deal with unconfirmed packets, but even if that could be done in a sane way this opens up other problems, for example: -m physdev --physdev-out eth0 -j SNAT --snat-to 1.2.3.4 -m physdev --physdev-out eth1 -j SNAT --snat-to 1.2.3.5 For multicast case, only one of such conflicting mappings will be created, conntrack only handles 1:1 NAT mappings. Users should set create a setup that explicitly marks such traffic NOTRACK (conntrack bypass) to avoid this, but we cannot auto-bypass them, ruleset might have accept rules for untracked traffic already, so user-visible behaviour would change. Suggested-by: Pablo Neira Ayuso Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217777 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: move nf_reinject into nfnetlink_queue modules

2024-02-21T11:03:22+00:00

No need to keep this in the core, move it to the nfnetlink_queue module. nf_reroute is moved too, there were no other callers. Signed-off-by: Florian Westphal

netfilter: make nftables drops visible in net dropmonitor

2023-10-18T08:26:43+00:00

net_dropmonitor blames core.c:nf_hook_slow. Add NF_DROP_REASON() helper and use it in nft_do_chain(). The helper releases the skb, so exact drop location becomes available. Calling code will observe the NF_STOLEN verdict instead. Adjust nf_hook_slow so we can embed an erro value wih NF_STOLEN verdicts, just like we do for NF_DROP. After this, drop in nftables can be pinpointed to a drop due to a rule or the chain policy. Signed-off-by: Florian Westphal

netfilter: defrag: Add glue hooks for enabling/disabling defrag

2023-07-28T23:52:08+00:00

We want to be able to enable/disable IP packet defrag from core bpf/netfilter code. In other words, execute code from core that could possibly be built as a module. To help avoid symbol resolution errors, use glue hooks that the modules will register callbacks with during module init. Signed-off-by: Daniel Xu Reviewed-by: Florian Westphal Link: https://lore.kernel.org/r/f6a8824052441b72afe5285acedbd634bd3384c1.1689970773.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov