udp: preserve head state for IP_CMSG_PASSSEC

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Paul Moore reported a SELinux/IP_PASSSEC regression
caused by missing skb->sp at recvmsg() time. We need to
preserve the skb head state to process the IP_CMSG_PASSSEC
cmsg.

With this commit we avoid releasing the skb head state in the
BH even if a secpath is attached to the current skb, and stores
the skb status (with/without head states) in the scratch area,
so that we can access it at skb deallocation time, without
incurring in cache-miss penalties.

This also avoids misusing the skb CB for ipv6 packets,
as introduced by the commit 0ddf3fb2c4 ("udp: preserve
skb->dst if required for IP options processing").

Clean a bit the scratch area helpers implementation, to
reduce the code differences between 32 and 64 bits build.

Reported-by: Paul Moore <paul@paul-moore.com>
Fixes: 0a463c78d2 ("udp: avoid a cache miss on dequeue")
Fixes: 0ddf3fb2c4 ("udp: preserve skb->dst if required for IP options processing")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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This commit is contained in:

Paolo Abeni 2017-07-25 17:57:47 +02:00 • committed by David S. Miller

parent 9f9e772da2

commit dce4551cb2

2 changed files with 40 additions and 31 deletions

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33

include/net/udp.h

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52

net/ipv4/udp.c

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