linux/include/net/netfilter, branch v6.15

Merge tag 'nf-next-25-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next

2025-03-25T15:29:13Z

Pablo Neira Ayuso says: ==================== Netfilter updates for net-next The following batch contains Netfilter updates for net-next: 1) Use kvmalloc in xt_hashlimit, from Denis Kirjanov. 2) Tighten nf_conntrack sysctl accepted values for nf_conntrack_max and nf_ct_expect_max, from Nicolas Bouchinet. 3) Avoid lookup in nft_fib if socket is available, from Florian Westphal. 4) Initialize struct lsm_context in nfnetlink_queue to avoid hypothetical ENOMEM errors, Chenyuan Yang. 5) Use strscpy() instead of _pad when initializing xtables table name, kzalloc is already used to initialized the table memory area. From Thorsten Blum. 6) Missing socket lookup by conntrack information for IPv6 traffic in nft_socket, there is a similar chunk in IPv4, this was never added when IPv6 NAT was introduced. From Maxim Mikityanskiy. 7) Fix clang issues with nf_tables CONFIG_MITIGATION_RETPOLINE, from WangYuli. * tag 'nf-next-25-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next: netfilter: nf_tables: Only use nf_skip_indirect_calls() when MITIGATION_RETPOLINE netfilter: socket: Lookup orig tuple for IPv6 SNAT netfilter: xtables: Use strscpy() instead of strscpy_pad() netfilter: nfnetlink_queue: Initialize ctx to avoid memory allocation error netfilter: fib: avoid lookup if socket is available netfilter: conntrack: Bound nf_conntrack sysctl writes netfilter: xt_hashlimit: replace vmalloc calls with kvmalloc ==================== Link: https://patch.msgid.link/20250323100922.59983-1-pablo@netfilter.org Signed-off-by: Jakub Kicinski

netfilter: fib: avoid lookup if socket is available

2025-03-21T09:12:15Z

In case the fib match is used from the input hook we can avoid the fib lookup if early demux assigned a socket for us: check that the input interface matches sk-cached one. Rework the existing 'lo bypass' logic to first check sk, then for loopback interface type to elide the fib lookup. This speeds up fib matching a little, before: 93.08 GBit/s (no rules at all) 75.1 GBit/s ("fib saddr . iif oif missing drop" in prerouting) 75.62 GBit/s ("fib saddr . iif oif missing drop" in input) After: 92.48 GBit/s (no rules at all) 75.62 GBit/s (fib rule in prerouting) 90.37 GBit/s (fib rule in input). Numbers for the 'no rules' and 'prerouting' are expected to closely match in-between runs, the 3rd/input test case exercises the the 'avoid lookup if cached ifindex in sk matches' case. Test used iperf3 via veth interface, lo can't be used due to existing loopback test. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: make destruction work queue pernet

2025-03-06T12:35:54Z

The call to flush_work before tearing down a table from the netlink notifier was supposed to make sure that all earlier updates (e.g. rule add) that might reference that table have been processed. Unfortunately, flush_work() waits for the last queued instance. This could be an instance that is different from the one that we must wait for. This is because transactions are protected with a pernet mutex, but the work item is global, so holding the transaction mutex doesn't prevent another netns from queueing more work. Make the work item pernet so that flush_work() will wait for all transactions queued from this netns. A welcome side effect is that we no longer need to wait for transaction objects from foreign netns. The gc work queue is still global. This seems to be ok because nft_set structures are reference counted and each container structure owns a reference on the net namespace. The destroy_list is still protected by a global spinlock rather than pernet one but the hold time is very short anyway. v2: call cancel_work_sync before reaping the remaining tables (Pablo). Fixes: 9f6958ba2e90 ("netfilter: nf_tables: unconditionally flush pending work before notifier") Reported-by: syzbot+5d8c5789c8cb076b2c25@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: flowtable: add CLOSING state

2025-01-19T15:41:56Z

tcp rst/fin packet triggers an immediate teardown of the flow which results in sending flows back to the classic forwarding path. This behaviour was introduced by: da5984e51063 ("netfilter: nf_flow_table: add support for sending flows back to the slow path") b6f27d322a0a ("netfilter: nf_flow_table: tear down TCP flows if RST or FIN was seen") whose goal is to expedite removal of flow entries from the hardware table. Before these patches, the flow was released after the flow entry timed out. However, this approach leads to packet races when restoring the conntrack state as well as late flow re-offload situations when the TCP connection is ending. This patch adds a new CLOSING state that is is entered when tcp rst/fin packet is seen. This allows for an early removal of the flow entry from the hardware table. But the flow entry still remains in software, so tcp packets to shut down the flow are not sent back to slow path. If syn packet is seen from this new CLOSING state, then this flow enters teardown state, ct state is set to TCP_CONNTRACK_CLOSE state and packet is sent to slow path, so this TCP reopen scenario can be handled by conntrack. TCP_CONNTRACK_CLOSE provides a small timeout that aims at quickly releasing this stale entry from the conntrack table. Moreover, skip hardware re-offload from flowtable software packet if the flow is in CLOSING state. Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: rework offload nf_conn timeout extension logic

2025-01-19T15:41:55Z

Offload nf_conn entries may not see traffic for a very long time. To prevent incorrect 'ct is stale' checks during nf_conntrack table lookup, the gc worker extends the timeout nf_conn entries marked for offload to a large value. The existing logic suffers from a few problems. Garbage collection runs without locks, its unlikely but possible that @ct is removed right after the 'offload' bit test. In that case, the timeout of a new/reallocated nf_conn entry will be increased. Prevent this by obtaining a reference count on the ct object and re-check of the confirmed and offload bits. If those are not set, the ct is being removed, skip the timeout extension in this case. Parallel teardown is also problematic: cpu1 cpu2 gc_worker calls flow_offload_teardown() tests OFFLOAD bit, set clear OFFLOAD bit ct->timeout is repaired (e.g. set to timeout[UDP_CT_REPLIED]) nf_ct_offload_timeout() called expire value is fetched -> NF_CT_DAY timeout for flow that isn't offloaded (and might not see any further packets). Use cmpxchg: if ct->timeout was repaired after the 2nd 'offload bit' test passed, then ct->timeout will only be updated of ct->timeout was not altered in between. As we already have a gc worker for flowtable entries, ct->timeout repair can be handled from the flowtable gc worker. This avoids having flowtable specific logic in the conntrack core and avoids checking entries that were never offloaded. This allows to remove the nf_ct_offload_timeout helper. Its safe to use in the add case, but not on teardown. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: remove skb argument from nf_ct_refresh

2025-01-19T15:41:55Z

Its not used (and could be NULL), so remove it. This allows to use nf_ct_refresh in places where we don't have an skb without having to double-check that skb == NULL would be safe. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: Tolerate chains with no remaining hooks

2025-01-19T15:41:54Z

Do not drop a netdev-family chain if the last interface it is registered for vanishes. Users dumping and storing the ruleset upon shutdown to restore it upon next boot may otherwise lose the chain and all contained rules. They will still lose the list of devices, a later patch will fix that. For now, this aligns the event handler's behaviour with that for flowtables. The controversal situation at netns exit should be no problem here: event handler will unregister the hooks, core nftables cleanup code will drop the chain itself. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: Store user-defined hook ifname

2025-01-19T15:41:53Z

Prepare for hooks with NULL ops.dev pointer (due to non-existent device) and store the interface name and length as specified by the user upon creation. No functional change intended. Signed-off-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso

netfilter: nf_tables: fix set size with rbtree backend

2025-01-19T15:41:41Z

The existing rbtree implementation uses singleton elements to represent ranges, however, userspace provides a set size according to the number of ranges in the set. Adjust provided userspace set size to the number of singleton elements in the kernel by multiplying the range by two. Check if the no-match all-zero element is already in the set, in such case release one slot in the set size. Fixes: 0ed6389c483d ("netfilter: nf_tables: rename set implementations") Signed-off-by: Pablo Neira Ayuso

netfilter: conntrack: add conntrack event timestamp

2025-01-09T13:42:16Z

Nadia Pinaeva writes: I am working on a tool that allows collecting network performance metrics by using conntrack events. Start time of a conntrack entry is used to evaluate seen_reply latency, therefore the sooner it is timestamped, the better the precision is. In particular, when using this tool to compare the performance of the same feature implemented using iptables/nftables/OVS it is crucial to have the entry timestamped earlier to see any difference. At this time, conntrack events can only get timestamped at recv time in userspace, so there can be some delay between the event being generated and the userspace process consuming the message. There is sys/net/netfilter/nf_conntrack_timestamp, which adds a 64bit timestamp (ns resolution) that records start and stop times, but its not suited for this either, start time is the 'hashtable insertion time', not 'conntrack allocation time'. There is concern that moving the start-time moment to conntrack allocation will add overhead in case of flooding, where conntrack entries are allocated and released right away without getting inserted into the hashtable. Also, even if this was changed it would not with events other than new (start time) and destroy (stop time). Pablo suggested to add new CTA_TIMESTAMP_EVENT, this adds this feature. The timestamp is recorded in case both events are requested and the sys/net/netfilter/nf_conntrack_timestamp toggle is enabled. Reported-by: Nadia Pinaeva Suggested-by: Pablo Neira Ayuso Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso