From dce4551cb2adb1ac9a30f8ab5299d614392b3cff Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 25 Jul 2017 17:57:47 +0200 Subject: udp: preserve head state for IP_CMSG_PASSSEC 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 0ddf3fb2c43d ("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 Fixes: 0a463c78d25b ("udp: avoid a cache miss on dequeue") Fixes: 0ddf3fb2c43d ("udp: preserve skb->dst if required for IP options processing") Signed-off-by: Paolo Abeni Tested-by: Paul Moore Signed-off-by: David S. Miller --- include/net/udp.h | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) (limited to 'include/net/udp.h') diff --git a/include/net/udp.h b/include/net/udp.h index 972ce4baab6b..56ce2d2a612d 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -305,33 +305,44 @@ struct sock *udp6_lib_lookup_skb(struct sk_buff *skb, /* UDP uses skb->dev_scratch to cache as much information as possible and avoid * possibly multiple cache miss on dequeue() */ -#if BITS_PER_LONG == 64 - -/* truesize, len and the bit needed to compute skb_csum_unnecessary will be on - * cold cache lines at recvmsg time. - * skb->len can be stored on 16 bits since the udp header has been already - * validated and pulled. - */ struct udp_dev_scratch { - u32 truesize; + /* skb->truesize and the stateless bit are embedded in a single field; + * do not use a bitfield since the compiler emits better/smaller code + * this way + */ + u32 _tsize_state; + +#if BITS_PER_LONG == 64 + /* len and the bit needed to compute skb_csum_unnecessary + * will be on cold cache lines at recvmsg time. + * skb->len can be stored on 16 bits since the udp header has been + * already validated and pulled. + */ u16 len; bool is_linear; bool csum_unnecessary; +#endif }; +static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb) +{ + return (struct udp_dev_scratch *)&skb->dev_scratch; +} + +#if BITS_PER_LONG == 64 static inline unsigned int udp_skb_len(struct sk_buff *skb) { - return ((struct udp_dev_scratch *)&skb->dev_scratch)->len; + return udp_skb_scratch(skb)->len; } static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb) { - return ((struct udp_dev_scratch *)&skb->dev_scratch)->csum_unnecessary; + return udp_skb_scratch(skb)->csum_unnecessary; } static inline bool udp_skb_is_linear(struct sk_buff *skb) { - return ((struct udp_dev_scratch *)&skb->dev_scratch)->is_linear; + return udp_skb_scratch(skb)->is_linear; } #else -- cgit v1.2.3