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Commit 56193d1b authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

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: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2c048e64

include/linux/etherdevice.h

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <asm/bitsperlong.h>



#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;

include/linux/skbuff.h

+3 −1
Original line number Diff line number Diff line
@@ -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

include/net/flow_keys.h

+2 −0
Original line number Diff line number Diff line
@@ -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

net/core/filter.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

net/core/flow_dissector.c

+32 −14
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/if_pppox.h>

#include <linux/ppp_defs.h>

#include <net/flow_keys.h>

#include <scsi/fc/fc_fcoe.h>



/* 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;



	if (!skb_flow_dissect(skb, &keys))

		return 0;

	u32 poff = keys->thoff;



	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