kernel/linux.git/include/linux/netfilter.h, branch v6.6.132

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

2024-03-06T14:48:36+00:00

[ Upstream commit 62e7151ae3eb465e0ab52a20c941ff33bb6332e9 ] 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 Signed-off-by: Sasha Levin

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

netfilter: let reset rules clean out conntrack entries

2023-02-17T12:04:56+00:00

iptables/nftables support responding to tcp packets with tcp resets. The generated tcp reset packet passes through both output and postrouting netfilter hooks, but conntrack will never see them because the generated skb has its ->nfct pointer copied over from the packet that triggered the reset rule. If the reset rule is used for established connections, this may result in the conntrack entry to be around for a very long time (default timeout is 5 days). One way to avoid this would be to not copy the nf_conn pointer so that the rest packet passes through conntrack too. Problem is that output rules might not have the same conntrack zone setup as the prerouting ones, so its possible that the reset skb won't find the correct entry. Generating a template entry for the skb seems error prone as well. Add an explicit "closing" function that switches a confirmed conntrack entry to closed state and wire this up for tcp. If the entry isn't confirmed, no action is needed because the conntrack entry will never be committed to the table. Reported-by: Russel King Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

Remove DECnet support from kernel

2022-08-22T13:26:30+00:00

DECnet is an obsolete network protocol that receives more attention from kernel janitors than users. It belongs in computer protocol history museum not in Linux kernel. It has been "Orphaned" in kernel since 2010. The iproute2 support for DECnet was dropped in 5.0 release. The documentation link on Sourceforge says it is abandoned there as well. Leave the UAPI alone to keep userspace programs compiling. This means that there is still an empty neighbour table for AF_DECNET. The table of /proc/sys/net entries was updated to match current directories and reformatted to be alphabetical. Signed-off-by: Stephen Hemminger Acked-by: David Ahern Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

netfilter: conntrack: handle ->destroy hook via nat_ops instead

2022-02-04T05:30:28+00:00

The nat module already exposes a few functions to the conntrack core. Move the nat extension destroy hook to it. After this, no conntrack extension needs a destroy hook. 'struct nf_ct_ext_type' and the register/unregister api can be removed in a followup patch. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso

netfilter: make function op structures const

2022-01-09T22:30:13+00:00

No functional changes, these structures should be const. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso