espintcp: remove encap socket caching to avoid reference leak

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[ Upstream commit 028363685b ]

The current scheme for caching the encap socket can lead to reference
leaks when we try to delete the netns.

The reference chain is: xfrm_state -> enacp_sk -> netns

Since the encap socket is a userspace socket, it holds a reference on
the netns. If we delete the espintcp state (through flush or
individual delete) before removing the netns, the reference on the
socket is dropped and the netns is correctly deleted. Otherwise, the
netns may not be reachable anymore (if all processes within the ns
have terminated), so we cannot delete the xfrm state to drop its
reference on the socket.

This patch results in a small (~2% in my tests) performance
regression.

A GC-type mechanism could be added for the socket cache, to clear
references if the state hasn't been used "recently", but it's a lot
more complex than just not caching the socket.

Fixes: e27cca96cd ("xfrm: add espintcp (RFC 8229)")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

This commit is contained in:

Sabrina Dubroca 2025-04-09 15:59:57 +02:00 • committed by Greg Kroah-Hartman

parent 3cf3d4f112

commit b58a295d10

4 changed files with 8 additions and 94 deletions

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1

include/net/xfrm.h

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49

net/ipv4/esp4.c

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49

net/ipv6/esp6.c

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3

net/xfrm/xfrm_state.c

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