From 5a21232983aa7acfe7fd26170832a9e0a4a7b4ae Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Sun, 31 Aug 2014 15:12:41 -0700 Subject: [PATCH] net: Support for csum_bad in skbuff This flag indicates that an invalid checksum was detected in the packet. __skb_mark_checksum_bad helper function was added to set this. Checksums can be marked bad from a driver or the GRO path (the latter is implemented in this patch). csum_bad is checked in __skb_checksum_validate_complete (i.e. calling that when ip_summed == CHECKSUM_NONE). csum_bad works in conjunction with ip_summed value. In the case that ip_summed is CHECKSUM_NONE and csum_bad is set, this implies that the first (or next) checksum encountered in the packet is bad. When ip_summed is CHECKSUM_UNNECESSARY, the first checksum after the last one validated is bad. For example, if ip_summed == CHECKSUM_UNNECESSARY, csum_level == 1, and csum_bad is set-- then the third checksum in the packet is bad. In the normal path, the packet will be dropped when processing the protocol layer of the bad checksum: __skb_decr_checksum_unnecessary called twice for the good checksums changing ip_summed to CHECKSUM_NONE so that __skb_checksum_validate_complete is called to validate the third checksum and that will fail since csum_bad is set. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- include/linux/netdevice.h | 4 +++- include/linux/skbuff.h | 21 ++++++++++++++++++++- net/core/dev.c | 2 +- 3 files changed, 24 insertions(+), 3 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 202c25a..a0ab6d9 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2216,7 +2216,9 @@ static inline void skb_gro_incr_csum_unnecessary(struct sk_buff *skb) if (__skb_gro_checksum_validate_needed(skb, zero_okay, check)) \ __ret = __skb_gro_checksum_validate_complete(skb, \ compute_pseudo(skb, proto)); \ - if (!__ret) \ + if (__ret) \ + __skb_mark_checksum_bad(skb); \ + else \ skb_gro_incr_csum_unnecessary(skb); \ __ret; \ }) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index c93b585..23710a2 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -617,7 +617,8 @@ struct sk_buff { kmemcheck_bitfield_begin(flags3); __u8 csum_level:2; - /* 14 bit hole */ + __u8 csum_bad:1; + /* 13 bit hole */ kmemcheck_bitfield_end(flags3); __be16 inner_protocol; @@ -2825,6 +2826,21 @@ static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb) } } +static inline void __skb_mark_checksum_bad(struct sk_buff *skb) +{ + /* Mark current checksum as bad (typically called from GRO + * path). In the case that ip_summed is CHECKSUM_NONE + * this must be the first checksum encountered in the packet. + * When ip_summed is CHECKSUM_UNNECESSARY, this is the first + * checksum after the last one validated. For UDP, a zero + * checksum can not be marked as bad. + */ + + if (skb->ip_summed == CHECKSUM_NONE || + skb->ip_summed == CHECKSUM_UNNECESSARY) + skb->csum_bad = 1; +} + /* Check if we need to perform checksum complete validation. * * Returns true if checksum complete is needed, false otherwise @@ -2866,6 +2882,9 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb, skb->csum_valid = 1; return 0; } + } else if (skb->csum_bad) { + /* ip_summed == CHECKSUM_NONE in this case */ + return 1; } skb->csum = psum; diff --git a/net/core/dev.c b/net/core/dev.c index 6857d57..3774afc 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3918,7 +3918,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff if (!(skb->dev->features & NETIF_F_GRO)) goto normal; - if (skb_is_gso(skb) || skb_has_frag_list(skb)) + if (skb_is_gso(skb) || skb_has_frag_list(skb) || skb->csum_bad) goto normal; gro_list_prepare(napi, skb); -- 2.7.4