[PATCH v2 1/3] net: Preserve CHECKSUM_COMPLETE at validation
From: Tom Herbert <hidden>
Date: 2014-06-11 01:54:14
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Currently when the first checksum in a packet is validated using CHECKSUM_COMPLETE, ip_summed is overwritten to be CHECKSUM_UNNECESSARY so that any subsequent checksums in the packet are not correctly validated. This patch adds csum_valid flag in sk_buff and uses that to indicate validated checksum instead of setting CHECKSUM_UNNECESSARY. The bit is set accordingly in the skb_checksum_validate_* functions. The flag is checked in skb_checksum_complete, so that validation is communicated between checksum_init and checksum_complete sequence in TCP and UDP. Signed-off-by: Tom Herbert <redacted> --- include/linux/skbuff.h | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c705808..fb44d5f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h@@ -572,7 +572,8 @@ struct sk_buff { */ __u8 encapsulation:1; __u8 encap_hdr_csum:1; - /* 5/7 bit hole (depending on ndisc_nodetype presence) */ + __u8 csum_valid:1; + /* 4/6 bit hole (depending on ndisc_nodetype presence) */ kmemcheck_bitfield_end(flags2); #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
@@ -2721,7 +2722,7 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb); static inline int skb_csum_unnecessary(const struct sk_buff *skb) { - return skb->ip_summed & CHECKSUM_UNNECESSARY; + return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid); } /**
@@ -2755,10 +2756,8 @@ static inline bool __skb_checksum_validate_needed(struct sk_buff *skb, bool zero_okay, __sum16 check) { - if (skb_csum_unnecessary(skb)) { - return false; - } else if (zero_okay && !check) { - skb->ip_summed = CHECKSUM_UNNECESSARY; + if (skb_csum_unnecessary(skb) || (zero_okay && !check)) { + skb->csum_valid = 1; return false; }
@@ -2785,15 +2784,20 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb, { if (skb->ip_summed == CHECKSUM_COMPLETE) { if (!csum_fold(csum_add(psum, skb->csum))) { - skb->ip_summed = CHECKSUM_UNNECESSARY; + skb->csum_valid = 1; return 0; } } skb->csum = psum; - if (complete || skb->len <= CHECKSUM_BREAK) - return __skb_checksum_complete(skb); + if (complete || skb->len <= CHECKSUM_BREAK) { + __sum16 csum; + + csum = __skb_checksum_complete(skb); + skb->csum_valid = !csum; + return csum; + } return 0; }
@@ -2817,6 +2821,7 @@ static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto) zero_okay, check, compute_pseudo) \ ({ \ __sum16 __ret = 0; \ + skb->csum_valid = 0; \ if (__skb_checksum_validate_needed(skb, zero_okay, check)) \ __ret = __skb_checksum_validate_complete(skb, \ complete, compute_pseudo(skb, proto)); \
--
2.0.0.526.g5318336