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

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
......@@ -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;
......
......@@ -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
......
......@@ -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
......@@ -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)
......
......@@ -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 @@ bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
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 @@ bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
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
......
......@@ -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
......
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