Messages in this thread | | | Date | Mon, 23 Oct 2023 19:35:32 -0700 | From | Yan Zhai <> | Subject | [PATCH v4 net-next 0/3] ipv6: avoid atomic fragment on GSO output |
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When the ipv6 stack output a GSO packet, if its gso_size is larger than dst MTU, then all segments would be fragmented. However, it is possible for a GSO packet to have a trailing segment with smaller actual size than both gso_size as well as the MTU, which leads to an "atomic fragment". Atomic fragments are considered harmful in RFC-8021. An Existing report from APNIC also shows that atomic fragments are more likely to be dropped even it is equivalent to a no-op [1].
The series contains following changes: * drop feature RTAX_FEATURE_ALLFRAG, which has been broken. This helps simplifying other changes in this set. * refactor __ip6_finish_output code to separate GSO and non-GSO packet processing, mirroring IPv4 side logic. * avoid generating atomic fragment on GSO packets.
Link: https://www.potaroo.net/presentations/2022-03-01-ipv6-frag.pdf [1]
change log: V3 -> V4: cleaned up all RTAX_FEATURE_ALLFRAG code, rather than just drop the check at IPv6 output. V2 -> V3: split the changes to separate commits as Willem de Bruijn suggested V1 is incorrect and omitted
V3: https://lore.kernel.org/netdev/cover.1697779681.git.yan@cloudflare.com/ V2: https://lore.kernel.org/netdev/ZS1%2Fqtr0dZJ35VII@debian.debian/
Yan Zhai (3): ipv6: drop feature RTAX_FEATURE_ALLFRAG ipv6: refactor ip6_finish_output for GSO handling ipv6: avoid atomic fragment on GSO packets
include/net/dst.h | 7 ----- include/net/inet_connection_sock.h | 1 - include/net/inet_sock.h | 2 +- include/uapi/linux/rtnetlink.h | 2 +- net/ipv4/tcp_output.c | 20 +------------ net/ipv6/ip6_output.c | 45 ++++++++++++++++-------------- net/ipv6/tcp_ipv6.c | 1 - net/ipv6/xfrm6_output.c | 2 +- net/mptcp/subflow.c | 1 - 9 files changed, 28 insertions(+), 53 deletions(-)
-- 2.30.2
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