From 2817a336d4d533fb8b68719723cd60ea7dd7c09e Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 30 Oct 2013 11:50:51 +0100 Subject: [PATCH] net: skb_checksum: allow custom update/combine for walking skb Currently, skb_checksum walks over 1) linearized, 2) frags[], and 3) frag_list data and calculats the one's complement, a 32 bit result suitable for feeding into itself or csum_tcpudp_magic(), but unsuitable for SCTP as we're calculating CRC32c there. Hence, in order to not re-implement the very same function in SCTP (and maybe other protocols) over and over again, use an update() + combine() callback internally to allow for walking over the skb with different algorithms. Signed-off-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/linux/skbuff.h | 13 ++++++++++--- include/net/checksum.h | 6 ++++++ net/core/skbuff.c | 31 +++++++++++++++++++++---------- 3 files changed, 37 insertions(+), 13 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 2c154976394b..44727b5d4981 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2360,8 +2360,6 @@ int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset, void skb_free_datagram(struct sock *sk, struct sk_buff *skb); void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb); int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags); -__wsum skb_checksum(const struct sk_buff *skb, int offset, int len, - __wsum csum); int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len); int skb_store_bits(struct sk_buff *skb, int offset, const void *from, int len); __wsum skb_copy_and_csum_bits(const struct sk_buff *skb, int offset, u8 *to, @@ -2373,9 +2371,18 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to); void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len); int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen); void skb_scrub_packet(struct sk_buff *skb, bool xnet); - struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features); +struct skb_checksum_ops { + __wsum (*update)(const void *mem, int len, __wsum wsum); + __wsum (*combine)(__wsum csum, __wsum csum2, int offset, int len); +}; + +__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, + __wsum csum, const struct skb_checksum_ops *ops); +__wsum skb_checksum(const struct sk_buff *skb, int offset, int len, + __wsum csum); + static inline void *skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer) { diff --git a/include/net/checksum.h b/include/net/checksum.h index 8f59ca50477c..15f33fde826e 100644 --- a/include/net/checksum.h +++ b/include/net/checksum.h @@ -78,6 +78,12 @@ csum_block_add(__wsum csum, __wsum csum2, int offset) return csum_add(csum, (__force __wsum)sum); } +static inline __wsum +csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) +{ + return csum_block_add(csum, csum2, offset); +} + static inline __wsum csum_block_sub(__wsum csum, __wsum csum2, int offset) { diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 0ab32faa520f..31aab5376cb4 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1928,9 +1928,8 @@ fault: EXPORT_SYMBOL(skb_store_bits); /* Checksum skb data. */ - -__wsum skb_checksum(const struct sk_buff *skb, int offset, - int len, __wsum csum) +__wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, + __wsum csum, const struct skb_checksum_ops *ops) { int start = skb_headlen(skb); int i, copy = start - offset; @@ -1941,7 +1940,7 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, if (copy > 0) { if (copy > len) copy = len; - csum = csum_partial(skb->data + offset, copy, csum); + csum = ops->update(skb->data + offset, copy, csum); if ((len -= copy) == 0) return csum; offset += copy; @@ -1962,10 +1961,10 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, if (copy > len) copy = len; vaddr = kmap_atomic(skb_frag_page(frag)); - csum2 = csum_partial(vaddr + frag->page_offset + - offset - start, copy, 0); + csum2 = ops->update(vaddr + frag->page_offset + + offset - start, copy, 0); kunmap_atomic(vaddr); - csum = csum_block_add(csum, csum2, pos); + csum = ops->combine(csum, csum2, pos, copy); if (!(len -= copy)) return csum; offset += copy; @@ -1984,9 +1983,9 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, __wsum csum2; if (copy > len) copy = len; - csum2 = skb_checksum(frag_iter, offset - start, - copy, 0); - csum = csum_block_add(csum, csum2, pos); + csum2 = __skb_checksum(frag_iter, offset - start, + copy, 0, ops); + csum = ops->combine(csum, csum2, pos, copy); if ((len -= copy) == 0) return csum; offset += copy; @@ -1998,6 +1997,18 @@ __wsum skb_checksum(const struct sk_buff *skb, int offset, return csum; } +EXPORT_SYMBOL(__skb_checksum); + +__wsum skb_checksum(const struct sk_buff *skb, int offset, + int len, __wsum csum) +{ + const struct skb_checksum_ops ops = { + .update = csum_partial, + .combine = csum_block_add_ext, + }; + + return __skb_checksum(skb, offset, len, csum, &ops); +} EXPORT_SYMBOL(skb_checksum); /* Both of above in one bottle. */ -- 2.30.2