kernel/linux.git/include/linux/netfilter.h, branch v6.12.80

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

linux/netfilter.h: fix kernel-doc warnings

2023-06-26T11:27:51+00:00

kernel-doc does not support DECLARE_PER_CPU(), so don't mark it with kernel-doc notation. One comment block is not kernel-doc notation, so just use "/*" to begin the comment. Quietens these warnings: netfilter.h:493: warning: Function parameter or member 'bool' not described in 'DECLARE_PER_CPU' netfilter.h:493: warning: Function parameter or member 'nf_skb_duplicated' not described in 'DECLARE_PER_CPU' netfilter.h:493: warning: expecting prototype for nf_skb_duplicated(). Prototype was for DECLARE_PER_CPU() instead netfilter.h:496: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst * Contains bitmask of ctnetlink event subscribers, if any. Fixes: e7c8899f3e6f ("netfilter: move tee_active to core") Fixes: fdf6491193e4 ("netfilter: ctnetlink: make event listener tracking global") Signed-off-by: Randy Dunlap Reviewed-by: Simon Horman Signed-off-by: Pablo Neira Ayuso

bpf: add bpf_link support for BPF_NETFILTER programs

2023-04-21T18:34:14+00:00

Add bpf_link support skeleton. To keep this reviewable, no bpf program can be invoked yet, if a program is attached only a c-stub is called and not the actual bpf program. Defaults to 'y' if both netfilter and bpf syscall are enabled in kconfig. Uapi example usage: union bpf_attr attr = { }; attr.link_create.prog_fd = progfd; attr.link_create.attach_type = 0; /* unused */ attr.link_create.netfilter.pf = PF_INET; attr.link_create.netfilter.hooknum = NF_INET_LOCAL_IN; attr.link_create.netfilter.priority = -128; err = bpf(BPF_LINK_CREATE, &attr, sizeof(attr)); ... this would attach progfd to ipv4:input hook. Such hook gets removed automatically if the calling program exits. BPF_NETFILTER program invocation is added in followup change. NF_HOOK_OP_BPF enum will eventually be read from nfnetlink_hook, it allows to tell userspace which program is attached at the given hook when user runs 'nft hook list' command rather than just the priority and not-very-helpful 'this hook runs a bpf prog but I can't tell which one'. Will also be used to disallow registration of two bpf programs with same priority in a followup patch. v4: arm32 cmpxchg only supports 32bit operand s/prio/priority/ v3: restrict prog attachment to ip/ip6 for now, lets lift restrictions if more use cases pop up (arptables, ebtables, netdev ingress/egress etc). Signed-off-by: Florian Westphal Link: https://lore.kernel.org/r/20230421170300.24115-2-fw@strlen.de Signed-off-by: Alexei Starovoitov

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf

2023-02-23T05:25:23+00:00

Pablo Neira Ayuso says: ==================== Netfilter fixes for net 1) Fix broken listing of set elements when table has an owner. 2) Fix conntrack refcount leak in ctnetlink with related conntrack entries, from Hangyu Hua. 3) Fix use-after-free/double-free in ctnetlink conntrack insert path, from Florian Westphal. 4) Fix ip6t_rpfilter with VRF, from Phil Sutter. 5) Fix use-after-free in ebtables reported by syzbot, also from Florian. 6) Use skb->len in xt_length to deal with IPv6 jumbo packets, from Xin Long. 7) Fix NETLINK_LISTEN_ALL_NSID with ctnetlink, from Florian Westphal. 8) Fix memleak in {ip_,ip6_,arp_}tables in ENOMEM error case, from Pavel Tikhomirov. * git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf: netfilter: x_tables: fix percpu counter block leak on error path when creating new netns netfilter: ctnetlink: make event listener tracking global netfilter: xt_length: use skb len to match in length_mt6 netfilter: ebtables: fix table blob use-after-free netfilter: ip6t_rpfilter: Fix regression with VRF interfaces netfilter: conntrack: fix rmmod double-free race netfilter: ctnetlink: fix possible refcount leak in ctnetlink_create_conntrack() netfilter: nf_tables: allow to fetch set elements when table has an owner ==================== Link: https://lore.kernel.org/r/20230222092137.88637-1-pablo@netfilter.org Signed-off-by: Jakub Kicinski

netfilter: ctnetlink: make event listener tracking global

2023-02-21T23:28:47+00:00

pernet tracking doesn't work correctly because other netns might have set NETLINK_LISTEN_ALL_NSID on its event socket. In this case its expected that events originating in other net namespaces are also received. Making pernet-tracking work while also honoring NETLINK_LISTEN_ALL_NSID requires much more intrusive changes both in netlink and nfnetlink, f.e. adding a 'setsockopt' callback that lets nfnetlink know that the event socket entered (or left) ALL_NSID mode. Move to global tracking instead: if there is an event socket anywhere on the system, all net namespaces which have conntrack enabled and use autobind mode will allocate the ecache extension. netlink_has_listeners() returns false only if the given group has no subscribers in any net namespace, the 'net' argument passed to nfnetlink_has_listeners is only used to derive the protocol (nfnetlink), it has no other effect. For proper NETLINK_LISTEN_ALL_NSID-aware pernet tracking of event listeners a new netlink_has_net_listeners() is also needed. Fixes: 90d1daa45849 ("netfilter: conntrack: add nf_conntrack_events autodetect mode") Reported-by: Bryce Kahle Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso