kernel/linux.git/net/openvswitch/actions.c, branch v6.6.131

net: openvswitch: remove never-working support for setting nsh fields

2025-12-01T10:41:46+00:00

[ Upstream commit dfe28c4167a9259fc0c372d9f9473e1ac95cff67 ] The validation of the set(nsh(...)) action is completely wrong. It runs through the nsh_key_put_from_nlattr() function that is the same function that validates NSH keys for the flow match and the push_nsh() action. However, the set(nsh(...)) has a very different memory layout. Nested attributes in there are doubled in size in case of the masked set(). That makes proper validation impossible. There is also confusion in the code between the 'masked' flag, that says that the nested attributes are doubled in size containing both the value and the mask, and the 'is_mask' that says that the value we're parsing is the mask. This is causing kernel crash on trying to write into mask part of the match with SW_FLOW_KEY_PUT() during validation, while validate_nsh() doesn't allocate any memory for it: BUG: kernel NULL pointer dereference, address: 0000000000000018 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 1c2383067 P4D 1c2383067 PUD 20b703067 PMD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 8 UID: 0 Kdump: loaded Not tainted 6.17.0-rc4+ #107 PREEMPT(voluntary) RIP: 0010:nsh_key_put_from_nlattr+0x19d/0x610 [openvswitch] Call Trace: validate_nsh+0x60/0x90 [openvswitch] validate_set.constprop.0+0x270/0x3c0 [openvswitch] __ovs_nla_copy_actions+0x477/0x860 [openvswitch] ovs_nla_copy_actions+0x8d/0x100 [openvswitch] ovs_packet_cmd_execute+0x1cc/0x310 [openvswitch] genl_family_rcv_msg_doit+0xdb/0x130 genl_family_rcv_msg+0x14b/0x220 genl_rcv_msg+0x47/0xa0 netlink_rcv_skb+0x53/0x100 genl_rcv+0x24/0x40 netlink_unicast+0x280/0x3b0 netlink_sendmsg+0x1f7/0x430 ____sys_sendmsg+0x36b/0x3a0 ___sys_sendmsg+0x87/0xd0 __sys_sendmsg+0x6d/0xd0 do_syscall_64+0x7b/0x2c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e The third issue with this process is that while trying to convert the non-masked set into masked one, validate_set() copies and doubles the size of the OVS_KEY_ATTR_NSH as if it didn't have any nested attributes. It should be copying each nested attribute and doubling them in size independently. And the process must be properly reversed during the conversion back from masked to a non-masked variant during the flow dump. In the end, the only two outcomes of trying to use this action are either validation failure or a kernel crash. And if somehow someone manages to install a flow with such an action, it will most definitely not do what it is supposed to, since all the keys and the masks are mixed up. Fixing all the issues is a complex task as it requires re-writing most of the validation code. Given that and the fact that this functionality never worked since introduction, let's just remove it altogether. It's better to re-introduce it later with a proper implementation instead of trying to fix it in stable releases. Fixes: b2d0f5d5dc53 ("openvswitch: enable NSH support") Reported-by: Junvy Yang Signed-off-by: Ilya Maximets Acked-by: Eelco Chaudron Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20251112112246.95064-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

openvswitch: Fix unsafe attribute parsing in output_userspace()

2025-05-18T06:24:04+00:00

commit 6beb6835c1fbb3f676aebb51a5fee6b77fed9308 upstream. This patch replaces the manual Netlink attribute iteration in output_userspace() with nla_for_each_nested(), which ensures that only well-formed attributes are processed. Fixes: ccb1352e76cf ("net: Add Open vSwitch kernel components.") Signed-off-by: Eelco Chaudron Acked-by: Ilya Maximets Acked-by: Aaron Conole Link: https://patch.msgid.link/0bd65949df61591d9171c0dc13e42cea8941da10.1746541734.git.echaudro@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

tunnels: Accept PACKET_HOST in skb_tunnel_check_pmtu().

2025-04-10T12:37:40+00:00

[ Upstream commit 8930424777e43257f5bf6f0f0f53defd0d30415c ] Because skb_tunnel_check_pmtu() doesn't handle PACKET_HOST packets, commit 30a92c9e3d6b ("openvswitch: Set the skbuff pkt_type for proper pmtud support.") forced skb->pkt_type to PACKET_OUTGOING for openvswitch packets that are sent using the OVS_ACTION_ATTR_OUTPUT action. This allowed such packets to invoke the iptunnel_pmtud_check_icmp() or iptunnel_pmtud_check_icmpv6() helpers and thus trigger PMTU update on the input device. However, this also broke other parts of PMTU discovery. Since these packets don't have the PACKET_HOST type anymore, they won't trigger the sending of ICMP Fragmentation Needed or Packet Too Big messages to remote hosts when oversized (see the skb_in->pkt_type condition in __icmp_send() for example). These two skb->pkt_type checks are therefore incompatible as one requires skb->pkt_type to be PACKET_HOST, while the other requires it to be anything but PACKET_HOST. It makes sense to not trigger ICMP messages for non-PACKET_HOST packets as these messages should be generated only for incoming l2-unicast packets. However there doesn't seem to be any reason for skb_tunnel_check_pmtu() to ignore PACKET_HOST packets. Allow both cases to work by allowing skb_tunnel_check_pmtu() to work on PACKET_HOST packets and not overriding skb->pkt_type in openvswitch anymore. Fixes: 30a92c9e3d6b ("openvswitch: Set the skbuff pkt_type for proper pmtud support.") Fixes: 4cb47a8644cc ("tunnels: PMTU discovery support for directly bridged IP packets") Signed-off-by: Guillaume Nault Reviewed-by: Stefano Brivio Reviewed-by: Aaron Conole Tested-by: Aaron Conole Link: https://patch.msgid.link/eac941652b86fddf8909df9b3bf0d97bc9444793.1743208264.git.gnault@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

openvswitch: fix lockup on tx to unregistering netdev with carrier

2025-01-23T16:21:09+00:00

[ Upstream commit 47e55e4b410f7d552e43011baa5be1aab4093990 ] Commit in a fixes tag attempted to fix the issue in the following sequence of calls: do_output -> ovs_vport_send -> dev_queue_xmit -> __dev_queue_xmit -> netdev_core_pick_tx -> skb_tx_hash When device is unregistering, the 'dev->real_num_tx_queues' goes to zero and the 'while (unlikely(hash >= qcount))' loop inside the 'skb_tx_hash' becomes infinite, locking up the core forever. But unfortunately, checking just the carrier status is not enough to fix the issue, because some devices may still be in unregistering state while reporting carrier status OK. One example of such device is a net/dummy. It sets carrier ON on start, but it doesn't implement .ndo_stop to set the carrier off. And it makes sense, because dummy doesn't really have a carrier. Therefore, while this device is unregistering, it's still easy to hit the infinite loop in the skb_tx_hash() from the OVS datapath. There might be other drivers that do the same, but dummy by itself is important for the OVS ecosystem, because it is frequently used as a packet sink for tcpdump while debugging OVS deployments. And when the issue is hit, the only way to recover is to reboot. Fix that by also checking if the device is running. The running state is handled by the net core during unregistering, so it covers unregistering case better, and we don't really need to send packets to devices that are not running anyway. While only checking the running state might be enough, the carrier check is preserved. The running and the carrier states seem disjoined throughout the code and different drivers. And other core functions like __dev_direct_xmit() check both before attempting to transmit a packet. So, it seems safer to check both flags in OVS as well. Fixes: 066b86787fa3 ("net: openvswitch: fix race on port output") Reported-by: Friedrich Weber Closes: https://mail.openvswitch.org/pipermail/ovs-discuss/2025-January/053423.html Signed-off-by: Ilya Maximets Tested-by: Friedrich Weber Reviewed-by: Aaron Conole Link: https://patch.msgid.link/20250109122225.4034688-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

openvswitch: Set the skbuff pkt_type for proper pmtud support.

2024-06-12T09:12:49+00:00

[ Upstream commit 30a92c9e3d6b073932762bef2ac66f4ee784c657 ] Open vSwitch is originally intended to switch at layer 2, only dealing with Ethernet frames. With the introduction of l3 tunnels support, it crossed into the realm of needing to care a bit about some routing details when making forwarding decisions. If an oversized packet would need to be fragmented during this forwarding decision, there is a chance for pmtu to get involved and generate a routing exception. This is gated by the skbuff->pkt_type field. When a flow is already loaded into the openvswitch module this field is set up and transitioned properly as a packet moves from one port to another. In the case that a packet execute is invoked after a flow is newly installed this field is not properly initialized. This causes the pmtud mechanism to omit sending the required exception messages across the tunnel boundary and a second attempt needs to be made to make sure that the routing exception is properly setup. To fix this, we set the outgoing packet's pkt_type to PACKET_OUTGOING, since it can only get to the openvswitch module via a port device or packet command. Even for bridge ports as users, the pkt_type needs to be reset when doing the transmit as the packet is truly outgoing and routing needs to get involved post packet transformations, in the case of VXLAN/GENEVE/udp-tunnel packets. In general, the pkt_type on output gets ignored, since we go straight to the driver, but in the case of tunnel ports they go through IP routing layer. This issue is periodically encountered in complex setups, such as large openshift deployments, where multiple sets of tunnel traversal occurs. A way to recreate this is with the ovn-heater project that can setup a networking environment which mimics such large deployments. We need larger environments for this because we need to ensure that flow misses occur. In these environment, without this patch, we can see: ./ovn_cluster.sh start podman exec ovn-chassis-1 ip r a 170.168.0.5/32 dev eth1 mtu 1200 podman exec ovn-chassis-1 ip netns exec sw01p1 ip r flush cache podman exec ovn-chassis-1 ip netns exec sw01p1 \ ping 21.0.0.3 -M do -s 1300 -c2 PING 21.0.0.3 (21.0.0.3) 1300(1328) bytes of data. From 21.0.0.3 icmp_seq=2 Frag needed and DF set (mtu = 1142) --- 21.0.0.3 ping statistics --- ... Using tcpdump, we can also see the expected ICMP FRAG_NEEDED message is not sent into the server. With this patch, setting the pkt_type, we see the following: podman exec ovn-chassis-1 ip netns exec sw01p1 \ ping 21.0.0.3 -M do -s 1300 -c2 PING 21.0.0.3 (21.0.0.3) 1300(1328) bytes of data. From 21.0.0.3 icmp_seq=1 Frag needed and DF set (mtu = 1222) ping: local error: message too long, mtu=1222 --- 21.0.0.3 ping statistics --- ... In this case, the first ping request receives the FRAG_NEEDED message and a local routing exception is created. Tested-by: Jaime Caamano Reported-at: https://issues.redhat.com/browse/FDP-164 Fixes: 58264848a5a7 ("openvswitch: Add vxlan tunneling support.") Signed-off-by: Aaron Conole Acked-by: Eelco Chaudron Link: https://lore.kernel.org/r/20240516200941.16152-1-aconole@redhat.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: openvswitch: add misc error drop reasons

2023-08-14T07:01:06+00:00

Use drop reasons from include/net/dropreason-core.h when a reasonable candidate exists. Acked-by: Aaron Conole Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller

net: openvswitch: add meter drop reason

2023-08-14T07:01:06+00:00

By using an independent drop reason it makes it easy to distinguish between QoS-triggered or flow-triggered drop. Acked-by: Aaron Conole Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller

net: openvswitch: add explicit drop action

2023-08-14T07:01:06+00:00

From: Eric Garver This adds an explicit drop action. This is used by OVS to drop packets for which it cannot determine what to do. An explicit action in the kernel allows passing the reason _why_ the packet is being dropped or zero to indicate no particular error happened (i.e: OVS intentionally dropped the packet). Since the error codes coming from userspace mean nothing for the kernel, we squash all of them into only two drop reasons: - OVS_DROP_EXPLICIT_WITH_ERROR to indicate a non-zero value was passed - OVS_DROP_EXPLICIT to indicate a zero value was passed (no error) e.g. trace all OVS dropped skbs # perf trace -e skb:kfree_skb --filter="reason >= 0x30000" [..] 106.023 ping/2465 skb:kfree_skb(skbaddr: 0xffffa0e8765f2000, \ location:0xffffffffc0d9b462, protocol: 2048, reason: 196611) reason: 196611 --> 0x30003 (OVS_DROP_EXPLICIT) Also, this patch allows ovs-dpctl.py to add explicit drop actions as: "drop" -> implicit empty-action drop "drop(0)" -> explicit non-error action drop "drop(42)" -> explicit error action drop Signed-off-by: Eric Garver Co-developed-by: Adrian Moreno Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller

net: openvswitch: add action error drop reason

2023-08-14T07:01:06+00:00

Add a drop reason for packets that are dropped because an action returns a non-zero error code. Acked-by: Aaron Conole Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller

net: openvswitch: add last-action drop reason

2023-08-14T07:01:06+00:00

Create a new drop reason subsystem for openvswitch and add the first drop reason to represent last-action drops. Last-action drops happen when a flow has an empty action list or there is no action that consumes the packet (output, userspace, recirc, etc). It is the most common way in which OVS drops packets. Implementation-wise, most of these skb-consuming actions already call "consume_skb" internally and return directly from within the do_execute_actions() loop so with minimal changes we can assume that any skb that exits the loop normally is a packet drop. Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller