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Make datapath's flow_extract() properly pull data into the headers.

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Otherwise we might be reading headers that aren't really there.
This commit is contained in:
Ben Pfaff
2008-11-11 15:35:26 -08:00
parent 9171f24160
commit 182138487f
4 changed files with 71 additions and 85 deletions
Download Patch File Download Diff File Expand all files Collapse all files
datapath/Modules.mk
-1
View File
@@ -28,7 +28,6 @@ openflow_headers = \
nx_act.h \
nx_act_snat.h \
nx_msg.h \
snap.h \
table.h
dist_sources = $(foreach module,$(dist_modules),$($(module)_sources))
datapath/flow.c
+66 -52
View File
@@ -13,6 +13,7 @@
#include <linux/ip.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/llc.h>
#include <linux/module.h>
#include <linux/tcp.h>
#include <linux/udp.h>
@@ -22,7 +23,6 @@
#include "openflow/openflow.h"
#include "compat.h"
#include "snap.h"
struct kmem_cache *flow_cache;
@@ -275,10 +275,40 @@ void print_flow(const struct sw_flow_key *key)
}
EXPORT_SYMBOL(print_flow);
#define SNAP_OUI_LEN 3
struct eth_snap_hdr
{
struct ethhdr eth;
uint8_t dsap; /* Always 0xAA */
uint8_t ssap; /* Always 0xAA */
uint8_t ctrl;
uint8_t oui[SNAP_OUI_LEN];
uint16_t ethertype;
} __attribute__ ((packed));
static int is_snap(const struct eth_snap_hdr *esh)
{
return (esh->dsap == LLC_SAP_SNAP
&& esh->ssap == LLC_SAP_SNAP
&& !memcmp(esh->oui, "\0\0\0", 3));
}
static int iphdr_ok(struct sk_buff *skb)
{
int nh_ofs = skb_network_offset(skb);
if (skb->len >= nh_ofs + sizeof(struct iphdr)) {
int ip_len = ip_hdrlen(skb);
return (ip_len >= sizeof(struct iphdr)
&& pskb_may_pull(skb, nh_ofs + ip_len));
}
return 0;
}
static int tcphdr_ok(struct sk_buff *skb)
{
int th_ofs = skb_transport_offset(skb);
if (skb->len >= th_ofs + sizeof(struct tcphdr)) {
if (pskb_may_pull(skb, th_ofs + sizeof(struct tcphdr))) {
int tcp_len = tcp_hdrlen(skb);
return (tcp_len >= sizeof(struct tcphdr)
&& skb->len >= th_ofs + tcp_len);
@@ -289,7 +319,7 @@ static int tcphdr_ok(struct sk_buff *skb)
static int udphdr_ok(struct sk_buff *skb)
{
int th_ofs = skb_transport_offset(skb);
return skb->len >= th_ofs + sizeof(struct udphdr);
return pskb_may_pull(skb, th_ofs + sizeof(struct udphdr));
}
/* Parses the Ethernet frame in 'skb', which was received on 'in_port',
@@ -298,58 +328,55 @@ static int udphdr_ok(struct sk_buff *skb)
int flow_extract(struct sk_buff *skb, uint16_t in_port,
struct sw_flow_key *key)
{
struct ethhdr *mac;
int nh_ofs, th_ofs;
struct ethhdr *eth;
struct eth_snap_hdr *esh;
int retval = 0;
int nh_ofs;
memset(key, 0, sizeof *key);
key->dl_vlan = htons(OFP_VLAN_NONE);
key->in_port = htons(in_port);
key->pad = 0;
key->wildcards = 0;
key->nw_src_mask = 0;
key->nw_dst_mask = 0;
/* This code doesn't check that skb->len is long enough to contain the
* MAC or network header. With a 46-byte minimum length frame this
* assumption is always correct. */
if (skb->len < sizeof *eth)
return 0;
if (!pskb_may_pull(skb, skb->len >= 64 ? 64 : skb->len)) {
return 0;
}
/* Doesn't verify checksums. Should it? */
/* Data link layer. We only support Ethernet. */
mac = eth_hdr(skb);
nh_ofs = sizeof(struct ethhdr);
if (likely(ntohs(mac->h_proto) >= OFP_DL_TYPE_ETH2_CUTOFF)) {
/* This is an Ethernet II frame */
key->dl_type = mac->h_proto;
eth = eth_hdr(skb);
esh = (struct eth_snap_hdr *) eth;
nh_ofs = sizeof *eth;
if (likely(ntohs(eth->h_proto) >= OFP_DL_TYPE_ETH2_CUTOFF))
key->dl_type = eth->h_proto;
else if (skb->len >= sizeof *esh && is_snap(esh)) {
key->dl_type = esh->ethertype;
nh_ofs = sizeof *esh;
} else {
/* This is an 802.2 frame */
if (snap_get_ethertype(skb, &key->dl_type) != -EINVAL) {
nh_ofs += sizeof(struct snap_hdr);
} else {
key->dl_type = htons(OFP_DL_TYPE_NOT_ETH_TYPE);
nh_ofs += sizeof(struct llc_pdu_un);
key->dl_type = htons(OFP_DL_TYPE_NOT_ETH_TYPE);
if (skb->len >= nh_ofs + sizeof(struct llc_pdu_un)) {
nh_ofs += sizeof(struct llc_pdu_un);
}
}
/* Check for a VLAN tag */
if (likely(key->dl_type != htons(ETH_P_8021Q))) {
key->dl_vlan = htons(OFP_VLAN_NONE);
} else {
struct vlan_hdr *vh = (struct vlan_hdr *)(skb_mac_header(skb) + nh_ofs);
if (key->dl_type == htons(ETH_P_8021Q) &&
skb->len >= nh_ofs + sizeof(struct vlan_hdr)) {
struct vlan_hdr *vh = (struct vlan_hdr*)(skb->data + nh_ofs);
key->dl_type = vh->h_vlan_encapsulated_proto;
key->dl_vlan = vh->h_vlan_TCI & htons(VLAN_VID_MASK);
nh_ofs += sizeof(*vh);
nh_ofs += sizeof(struct vlan_hdr);
}
memcpy(key->dl_src, mac->h_source, ETH_ALEN);
memcpy(key->dl_dst, mac->h_dest, ETH_ALEN);
memcpy(key->dl_src, eth->h_source, ETH_ALEN);
memcpy(key->dl_dst, eth->h_dest, ETH_ALEN);
skb_set_network_header(skb, nh_ofs);
/* Network layer. */
if (likely(key->dl_type == htons(ETH_P_IP))) {
if (key->dl_type == htons(ETH_P_IP) && iphdr_ok(skb)) {
struct iphdr *nh = ip_hdr(skb);
int th_ofs = nh_ofs + nh->ihl * 4;
key->nw_src = nh->saddr;
key->nw_dst = nh->daddr;
key->nw_proto = nh->protocol;
th_ofs = nh_ofs + nh->ihl * 4;
skb_set_transport_header(skb, th_ofs);
/* Transport layer. */
@@ -363,7 +390,7 @@ int flow_extract(struct sk_buff *skb, uint16_t in_port,
/* Avoid tricking other code into
* thinking that this packet has an L4
* header. */
goto no_proto;
key->nw_proto = 0;
}
} else if (key->nw_proto == IPPROTO_UDP) {
if (udphdr_ok(skb)) {
@@ -374,28 +401,15 @@ int flow_extract(struct sk_buff *skb, uint16_t in_port,
/* Avoid tricking other code into
* thinking that this packet has an L4
* header. */
goto no_proto;
key->nw_proto = 0;
}
} else {
goto no_th;
}
} else {
retval = 1;
goto no_th;
}
return 0;
} else {
skb_reset_transport_header(skb);
}
key->nw_src = 0;
key->nw_dst = 0;
no_proto:
key->nw_proto = 0;
no_th:
key->tp_src = 0;
key->tp_dst = 0;
return retval;
}
datapath/linux-2.4/compat-2.4/include/linux/ip.h
+5
View File
@@ -10,6 +10,11 @@ static inline struct iphdr *ip_hdr(const struct sk_buff *skb)
{
return (struct iphdr *)skb_network_header(skb);
}
static inline unsigned int ip_hdrlen(const struct sk_buff *skb)
{
return ip_hdr(skb)->ihl * 4;
}
#endif
#endif
datapath/snap.h
-32
View File
@@ -1,32 +0,0 @@
#ifndef SNAP_H
#define SNAP_H 1
#include <linux/llc.h>
#define SNAP_OUI_LEN 3
struct snap_hdr
{
uint8_t dsap; /* Always 0xAA */
uint8_t ssap; /* Always 0xAA */
uint8_t ctrl;
uint8_t oui[SNAP_OUI_LEN];
uint16_t ethertype;
} __attribute__ ((packed));
static inline int snap_get_ethertype(struct sk_buff *skb, uint16_t *ethertype)
{
struct snap_hdr *sh = (struct snap_hdr *)(skb->data
+ sizeof(struct ethhdr));
if ((sh->dsap != LLC_SAP_SNAP)
|| (sh->ssap != LLC_SAP_SNAP)
|| (memcmp(sh->oui, "\0\0\0", SNAP_OUI_LEN)))
return -EINVAL;
*ethertype = sh->ethertype;
return 0;
}
#endif /* snap.h */