From 56193d1bce2b2759cb4bdcc00cd05544894a0c90 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Fri, 5 Sep 2014 19:20:26 -0400 Subject: [PATCH] net: Add function for parsing the header length out of linear ethernet frames This patch updates some of the flow_dissector api so that it can be used to parse the length of ethernet buffers stored in fragments. Most of the changes needed were to __skb_get_poff as it needed to be updated to support sending a linear buffer instead of a skb. I have split __skb_get_poff into two functions, the first is skb_get_poff and it retains the functionality of the original __skb_get_poff. The other function is __skb_get_poff which now works much like __skb_flow_dissect in relation to skb_flow_dissect in that it provides the same functionality but works with just a data buffer and hlen instead of needing an skb. Signed-off-by: Alexander Duyck Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/etherdevice.h | 1 + include/linux/skbuff.h | 4 +++- include/net/flow_keys.h | 2 ++ net/core/filter.c | 2 +- net/core/flow_dissector.c | 46 ++++++++++++++++++++++++++----------- net/ethernet/eth.c | 27 ++++++++++++++++++++++ 6 files changed, 66 insertions(+), 16 deletions(-) diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h index 9c5529dc6d07..733980fce8e3 100644 --- a/include/linux/etherdevice.h +++ b/include/linux/etherdevice.h @@ -29,6 +29,7 @@ #include #ifdef __KERNEL__ +u32 eth_get_headlen(void *data, unsigned int max_len); __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev); extern const struct header_ops eth_header_ops; diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 1cf0cfaef10a..07c9fdd0c126 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3218,7 +3218,9 @@ bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off); int skb_checksum_setup(struct sk_buff *skb, bool recalculate); -u32 __skb_get_poff(const struct sk_buff *skb); +u32 skb_get_poff(const struct sk_buff *skb); +u32 __skb_get_poff(const struct sk_buff *skb, void *data, + const struct flow_keys *keys, int hlen); /** * skb_head_is_locked - Determine if the skb->head is locked down diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h index 9a03f73c4974..7ee2df083542 100644 --- a/include/net/flow_keys.h +++ b/include/net/flow_keys.h @@ -40,4 +40,6 @@ static inline __be32 skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 return __skb_flow_get_ports(skb, thoff, ip_proto, NULL, 0); } u32 flow_hash_from_keys(struct flow_keys *keys); +unsigned int flow_get_hlen(const unsigned char *data, unsigned int max_len, + __be16 protocol); #endif diff --git a/net/core/filter.c b/net/core/filter.c index 37f8eb06fdee..fa5b7d0f77ac 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -113,7 +113,7 @@ static unsigned int pkt_type_offset(void) static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) { - return __skb_get_poff((struct sk_buff *)(unsigned long) ctx); + return skb_get_poff((struct sk_buff *)(unsigned long) ctx); } static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 12f48ca7a0b0..8560dea58803 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -13,6 +13,7 @@ #include #include #include +#include /* copy saddr & daddr, possibly using 64bit load/store * Equivalent to : flow->src = iph->saddr; @@ -117,6 +118,13 @@ ipv6: flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr); nhoff += sizeof(struct ipv6hdr); + /* skip the flow label processing if skb is NULL. The + * assumption here is that if there is no skb we are not + * looking for flow info as much as we are length. + */ + if (!skb) + break; + flow_label = ip6_flowlabel(iph); if (flow_label) { /* Awesome, IPv6 packet has a flow label so we can @@ -165,6 +173,9 @@ ipv6: return false; } } + case htons(ETH_P_FCOE): + flow->thoff = (u16)(nhoff + FCOE_HEADER_LEN); + /* fall through */ default: return false; } @@ -316,26 +327,18 @@ u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb, } EXPORT_SYMBOL(__skb_tx_hash); -/* __skb_get_poff() returns the offset to the payload as far as it could - * be dissected. The main user is currently BPF, so that we can dynamically - * truncate packets without needing to push actual payload to the user - * space and can analyze headers only, instead. - */ -u32 __skb_get_poff(const struct sk_buff *skb) +u32 __skb_get_poff(const struct sk_buff *skb, void *data, + const struct flow_keys *keys, int hlen) { - struct flow_keys keys; - u32 poff = 0; + u32 poff = keys->thoff; - if (!skb_flow_dissect(skb, &keys)) - return 0; - - poff += keys.thoff; - switch (keys.ip_proto) { + switch (keys->ip_proto) { case IPPROTO_TCP: { const struct tcphdr *tcph; struct tcphdr _tcph; - tcph = skb_header_pointer(skb, poff, sizeof(_tcph), &_tcph); + tcph = __skb_header_pointer(skb, poff, sizeof(_tcph), + data, hlen, &_tcph); if (!tcph) return poff; @@ -369,6 +372,21 @@ u32 __skb_get_poff(const struct sk_buff *skb) return poff; } +/* skb_get_poff() returns the offset to the payload as far as it could + * be dissected. The main user is currently BPF, so that we can dynamically + * truncate packets without needing to push actual payload to the user + * space and can analyze headers only, instead. + */ +u32 skb_get_poff(const struct sk_buff *skb) +{ + struct flow_keys keys; + + if (!skb_flow_dissect(skb, &keys)) + return 0; + + return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb)); +} + static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb) { #ifdef CONFIG_XPS diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index 5cebca134585..33a140e15834 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -145,6 +145,33 @@ int eth_rebuild_header(struct sk_buff *skb) } EXPORT_SYMBOL(eth_rebuild_header); +/** + * eth_get_headlen - determine the the length of header for an ethernet frame + * @data: pointer to start of frame + * @len: total length of frame + * + * Make a best effort attempt to pull the length for all of the headers for + * a given frame in a linear buffer. + */ +u32 eth_get_headlen(void *data, unsigned int len) +{ + const struct ethhdr *eth = (const struct ethhdr *)data; + struct flow_keys keys; + + /* this should never happen, but better safe than sorry */ + if (len < sizeof(*eth)) + return len; + + /* parse any remaining L2/L3 headers, check for L4 */ + if (!__skb_flow_dissect(NULL, &keys, data, + eth->h_proto, sizeof(*eth), len)) + return max_t(u32, keys.thoff, sizeof(*eth)); + + /* parse for any L4 headers */ + return min_t(u32, __skb_get_poff(NULL, data, &keys, len), len); +} +EXPORT_SYMBOL(eth_get_headlen); + /** * eth_type_trans - determine the packet's protocol ID. * @skb: received socket data