| Message ID | 20240326113403.397786-1-atenart@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | gro: various fixes related to UDP tunnels | expand |
Hello: This series was applied to netdev/net.git (main) by David S. Miller <davem@davemloft.net>: On Tue, 26 Mar 2024 12:33:57 +0100 you wrote: > Hello, > > We found issues when a UDP tunnel endpoint is in a different netns than > where UDP GRO happens. This kind of setup is actually quite diverse, > from having one leg of the tunnel on a remove host, to having a tunnel > between netns (eg. being bridged in another one or on the host). In our > case that UDP tunnel was geneve. > > [...] Here is the summary with links: - [net,v4,1/5] udp: do not accept non-tunnel GSO skbs landing in a tunnel https://git.kernel.org/netdev/net/c/3d010c8031e3 - [net,v4,2/5] gro: fix ownership transfer https://git.kernel.org/netdev/net/c/ed4cccef64c1 - [net,v4,3/5] udp: do not transition UDP GRO fraglist partial checksums to unnecessary https://git.kernel.org/netdev/net/c/f0b8c3034556 - [net,v4,4/5] udp: prevent local UDP tunnel packets from being GROed https://git.kernel.org/netdev/net/c/64235eabc4b5 - [net,v4,5/5] selftests: net: gro fwd: update vxlan GRO test expectations https://git.kernel.org/netdev/net/c/0fb101be97ca You are awesome, thank you!
Hello, We found issues when a UDP tunnel endpoint is in a different netns than where UDP GRO happens. This kind of setup is actually quite diverse, from having one leg of the tunnel on a remove host, to having a tunnel between netns (eg. being bridged in another one or on the host). In our case that UDP tunnel was geneve. UDP tunnel packets should not be GROed at the UDP level. The fundamental issue here is such packet can't be detected in a foolproof way: we can't know by looking at a packet alone and the current logic of looking up UDP sockets is fragile (socket could be in another netns, packet could be modified in between, etc). Because there is no way to make the GRO code to correctly handle those packets in all cases, this series aims at two things: making the net stack to correctly behave (as in, no crash and no invalid packet) when such thing happens, and in some cases to prevent this "early GRO" from happening. First three patches fix issues when an "UDP tunneled" packet is being GROed too early by rx-udp-gro-forwarding or rx-gro-list. Last patch is preventing locally generated UDP tunnel packets from being GROed. This turns out to be more complex than this patch alone as it relies on skb->encapsulation which is currently untrusty in some cases (see iptunnel_handle_offloads); but that should fix things in practice and is acceptable for a fix. Future work is required to improve things (prevent all locally generated UDP tunnel packets from being GROed), such as fixing the misuse of skb->encapsulation in drivers; but that would be net-next material. Thanks! Antoine Since v3: - Fixed the udpgro_fwd selftest in patch 5 (Jakub Kicinski feedback). - Improved commit message on patch 3 (Willem de Bruijn feeback). Since v2: - Fixed a build issue with IPv6=m in patch 1 (Jakub Kicinski feedback). - Fixed typo in patch 1 (Nikolay Aleksandrov feedback). - Added Reviewed-by tag on patch 2 (Willem de Bruijn feeback). - Added back conversion to CHECKSUM_UNNECESSARY but only from non CHECKSUM_PARTIAL in patch 3 (Paolo Abeni & Willem de Bruijn feeback). - Reworded patch 3 commit msg. Since v1: - Fixed a build issue with IPv6 disabled in patch 1. - Reworked commit log in patch 2 (Willem de Bruijn feedback). - Added Reviewed-by tags on patches 1 & 4 (Willem de Bruijn feeback). Antoine Tenart (5): udp: do not accept non-tunnel GSO skbs landing in a tunnel gro: fix ownership transfer udp: do not transition UDP GRO fraglist partial checksums to unnecessary udp: prevent local UDP tunnel packets from being GROed selftests: net: gro fwd: update vxlan GRO test expectations include/linux/udp.h | 28 +++++++++++++++++++++++ net/core/gro.c | 3 ++- net/ipv4/udp.c | 7 ++++++ net/ipv4/udp_offload.c | 23 +++++++++++-------- net/ipv6/udp.c | 2 +- net/ipv6/udp_offload.c | 8 +------ tools/testing/selftests/net/udpgro_fwd.sh | 10 ++------ 7 files changed, 54 insertions(+), 27 deletions(-)