kernel/linux.git/net/openvswitch/datapath.c, branch v6.19.11

net: openvswitch: allow providing upcall pid for the 'execute' command

2025-07-07T21:30:39+00:00

When a packet enters OVS datapath and there is no flow to handle it, packet goes to userspace through a MISS upcall. With per-CPU upcall dispatch mechanism, we're using the current CPU id to select the Netlink PID on which to send this packet. This allows us to send packets from the same traffic flow through the same handler. The handler will process the packet, install required flow into the kernel and re-inject the original packet via OVS_PACKET_CMD_EXECUTE. While handling OVS_PACKET_CMD_EXECUTE, however, we may hit a recirculation action that will pass the (likely modified) packet through the flow lookup again. And if the flow is not found, the packet will be sent to userspace again through another MISS upcall. However, the handler thread in userspace is likely running on a different CPU core, and the OVS_PACKET_CMD_EXECUTE request is handled in the syscall context of that thread. So, when the time comes to send the packet through another upcall, the per-CPU dispatch will choose a different Netlink PID, and this packet will end up processed by a different handler thread on a different CPU. The process continues as long as there are new recirculations, each time the packet goes to a different handler thread before it is sent out of the OVS datapath to the destination port. In real setups the number of recirculations can go up to 4 or 5, sometimes more. There is always a chance to re-order packets while processing upcalls, because userspace will first install the flow and then re-inject the original packet. So, there is a race window when the flow is already installed and the second packet can match it and be forwarded to the destination before the first packet is re-injected. But the fact that packets are going through multiple upcalls handled by different userspace threads makes the reordering noticeably more likely, because we not only have a race between the kernel and a userspace handler (which is hard to avoid), but also between multiple userspace handlers. For example, let's assume that 10 packets got enqueued through a MISS upcall for handler-1, it will start processing them, will install the flow into the kernel and start re-injecting packets back, from where they will go through another MISS to handler-2. Handler-2 will install the flow into the kernel and start re-injecting the packets, while handler-1 continues to re-inject the last of the 10 packets, they will hit the flow installed by handler-2 and be forwarded without going to the handler-2, while handler-2 still re-injects the first of these 10 packets. Given multiple recirculations and misses, these 10 packets may end up completely mixed up on the output from the datapath. Let's allow userspace to specify on which Netlink PID the packets should be upcalled while processing OVS_PACKET_CMD_EXECUTE. This makes it possible to ensure that all the packets are processed by the same handler thread in the userspace even with them being upcalled multiple times in the process. Packets will remain in order since they will be enqueued to the same socket and re-injected in the same order. This doesn't eliminate re-ordering as stated above, since we still have a race between kernel and the userspace thread, but it allows to eliminate races between multiple userspace threads. Userspace knows the PID of the socket on which the original upcall is received, so there is no need to send it up from the kernel. Solution requires storing the value somewhere for the duration of the packet processing. There are two potential places for this: our skb extension or the per-CPU storage. It's not clear which is better, so just following currently used scheme of storing this kind of things along the skb. We still have a decent amount of space in the cb. Signed-off-by: Ilya Maximets Acked-by: Flavio Leitner Acked-by: Eelco Chaudron Acked-by: Aaron Conole Link: https://patch.msgid.link/20250702155043.2331772-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

openvswitch: Allocate struct ovs_pcpu_storage dynamically

2025-06-17T12:47:46+00:00

PERCPU_MODULE_RESERVE defines the maximum size that can by used for the per-CPU data size used by modules. This is 8KiB. Commit 035fcdc4d240c ("openvswitch: Merge three per-CPU structures into one") restructured the per-CPU memory allocation for the module and moved the separate alloc_percpu() invocations at module init time to a static per-CPU variable which is allocated by the module loader. The size of the per-CPU data section for openvswitch is 6488 bytes which is ~80% of the available per-CPU memory. Together with a few other modules it is easy to exhaust the available 8KiB of memory. Allocate ovs_pcpu_storage dynamically at module init time. Reported-by: Gal Pressman Closes: https://lore.kernel.org/all/c401e017-f8db-4f57-a1cd-89beb979a277@nvidia.com Fixes: 035fcdc4d240c ("openvswitch: Merge three per-CPU structures into one") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20250613123629.-XSoQTCu@linutronix.de Signed-off-by: Paolo Abeni

openvswitch: Use nested-BH locking for ovs_pcpu_storage

2025-05-15T13:23:31+00:00

ovs_pcpu_storage 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. The data structure can be referenced recursive and there is a recursion counter to avoid too many recursions. Add a local_lock_t to the data structure and use local_lock_nested_bh() for locking. Add an owner of the struct which is the current task and acquire the lock only if the structure is not owned by the current task. Cc: Aaron Conole Cc: Eelco Chaudron Cc: Ilya Maximets Cc: dev@openvswitch.org Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20250512092736.229935-9-bigeasy@linutronix.de Signed-off-by: Paolo Abeni

openvswitch: Merge three per-CPU structures into one

2025-05-15T13:23:31+00:00

exec_actions_level is a per-CPU integer allocated at compile time. action_fifos and flow_keys are per-CPU pointer and have their data allocated at module init time. There is no gain in splitting it, once the module is allocated, the structures are allocated. Merge the three per-CPU variables into ovs_pcpu_storage, adapt callers. Cc: Aaron Conole Cc: Eelco Chaudron Cc: Ilya Maximets Cc: dev@openvswitch.org Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20250512092736.229935-8-bigeasy@linutronix.de Signed-off-by: Paolo Abeni

openvswitch: use RCU protection in ovs_vport_cmd_fill_info()

2025-02-11T02:09:09+00:00

ovs_vport_cmd_fill_info() can be called without RTNL or RCU. Use RCU protection and dev_net_rcu() to avoid potential UAF. Fixes: 9354d4520342 ("openvswitch: reliable interface indentification in port dumps") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-6-edumazet@google.com Signed-off-by: Jakub Kicinski

net: convert to nla_get_*_default()

2024-11-11T18:32:06+00:00

Most of the original conversion is from the spatch below, but I edited some and left out other instances that were either buggy after conversion (where default values don't fit into the type) or just looked strange. @@ expression attr, def; expression val; identifier fn =~ "^nla_get_.*"; fresh identifier dfn = fn ## "_default"; @@ ( -if (attr) - val = fn(attr); -else - val = def; +val = dfn(attr, def); | -if (!attr) - val = def; -else - val = fn(attr); +val = dfn(attr, def); | -if (!attr) - return def; -return fn(attr); +return dfn(attr, def); | -attr ? fn(attr) : def +dfn(attr, def) | -!attr ? def : fn(attr) +dfn(attr, def) ) Signed-off-by: Johannes Berg Reviewed-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20241108114145.0580b8684e7f.I740beeaa2f70ebfc19bfca1045a24d6151992790@changeid Signed-off-by: Jakub Kicinski

net: ovs: fix ovs_drop_reasons error

2024-08-22T20:09:15+00:00

There is something wrong with ovs_drop_reasons. ovs_drop_reasons[0] is "OVS_DROP_LAST_ACTION", but OVS_DROP_LAST_ACTION == __OVS_DROP_REASON + 1, which means that ovs_drop_reasons[1] should be "OVS_DROP_LAST_ACTION". And as Adrian tested, without the patch, adding flow to drop packets results in: drop at: do_execute_actions+0x197/0xb20 [openvsw (0xffffffffc0db6f97) origin: software input port ifindex: 8 timestamp: Tue Aug 20 10:19:17 2024 859853461 nsec protocol: 0x800 length: 98 original length: 98 drop reason: OVS_DROP_ACTION_ERROR With the patch, the same results in: drop at: do_execute_actions+0x197/0xb20 [openvsw (0xffffffffc0db6f97) origin: software input port ifindex: 8 timestamp: Tue Aug 20 10:16:13 2024 475856608 nsec protocol: 0x800 length: 98 original length: 98 drop reason: OVS_DROP_LAST_ACTION Fix this by initializing ovs_drop_reasons with index. Fixes: 9d802da40b7c ("net: openvswitch: add last-action drop reason") Signed-off-by: Menglong Dong Tested-by: Adrian Moreno Reviewed-by: Adrian Moreno Link: https://patch.msgid.link/20240821123252.186305-1-dongml2@chinatelecom.cn Signed-off-by: Jakub Kicinski

genetlink: remove linux/genetlink.h

2024-04-02T04:44:34+00:00

genetlink.h is a shell of what used to be a combined uAPI and kernel header over a decade ago. It has fewer than 10 lines of code. Merge it into net/genetlink.h. In some ways it'd be better to keep the combined header under linux/ but it would make looking through git history harder. Acked-by: Sven Eckelmann Link: https://lore.kernel.org/r/20240329175710.291749-4-kuba@kernel.org Signed-off-by: Jakub Kicinski

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

2023-08-18T19:44:56+00:00

Cross-merge networking fixes after downstream PR. Conflicts: drivers/net/ethernet/sfc/tc.c fa165e194997 ("sfc: don't unregister flow_indr if it was never registered") 3bf969e88ada ("sfc: add MAE table machinery for conntrack table") https://lore.kernel.org/all/20230818112159.7430e9b4@canb.auug.org.au/ No adjacent changes. Signed-off-by: Jakub Kicinski

net: openvswitch: reject negative ifindex

2023-08-16T02:07:52+00:00

Recent changes in net-next (commit 759ab1edb56c ("net: store netdevs in an xarray")) refactored the handling of pre-assigned ifindexes and let syzbot surface a latent problem in ovs. ovs does not validate ifindex, making it possible to create netdev ports with negative ifindex values. It's easy to repro with YNL: $ ./cli.py --spec netlink/specs/ovs_datapath.yaml \ --do new \ --json '{"upcall-pid": 1, "name":"my-dp"}' $ ./cli.py --spec netlink/specs/ovs_vport.yaml \ --do new \ --json '{"upcall-pid": "00000001", "name": "some-port0", "dp-ifindex":3,"ifindex":4294901760,"type":2}' $ ip link show -65536: some-port0: mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000 link/ether 7a:48:21:ad:0b:fb brd ff:ff:ff:ff:ff:ff ... Validate the inputs. Now the second command correctly returns: $ ./cli.py --spec netlink/specs/ovs_vport.yaml \ --do new \ --json '{"upcall-pid": "00000001", "name": "some-port0", "dp-ifindex":3,"ifindex":4294901760,"type":2}' lib.ynl.NlError: Netlink error: Numerical result out of range nl_len = 108 (92) nl_flags = 0x300 nl_type = 2 error: -34 extack: {'msg': 'integer out of range', 'unknown': [[type:4 len:36] b'\x0c\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x03\x00\xff\xff\xff\x7f\x00\x00\x00\x00\x08\x00\x01\x00\x08\x00\x00\x00'], 'bad-attr': '.ifindex'} Accept 0 since it used to be silently ignored. Fixes: 54c4ef34c4b6 ("openvswitch: allow specifying ifindex of new interfaces") Reported-by: syzbot+7456b5dcf65111553320@syzkaller.appspotmail.com Reviewed-by: Leon Romanovsky Reviewed-by: Aaron Conole Link: https://lore.kernel.org/r/20230814203840.2908710-1-kuba@kernel.org Signed-off-by: Jakub Kicinski