2 * Distributed under the terms of the GNU GPL version 2.
3 * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
5 * Significant portions of this file may be copied from parts of the Linux
6 * kernel, by Linus Torvalds and others.
9 /* Functions for executing flow actions. */
11 #include <linux/skbuff.h>
14 #include <linux/tcp.h>
15 #include <linux/udp.h>
16 #include <linux/in6.h>
17 #include <linux/if_arp.h>
18 #include <linux/if_vlan.h>
19 #include <net/inet_ecn.h>
21 #include <net/checksum.h>
25 #include "openvswitch/datapath-protocol.h"
28 static struct sk_buff *make_writable(struct sk_buff *skb, unsigned min_headroom)
30 if (skb_cloned(skb)) {
32 unsigned headroom = max(min_headroom, skb_headroom(skb));
34 nskb = skb_copy_expand(skb, headroom, skb_tailroom(skb), GFP_ATOMIC);
36 set_skb_csum_bits(skb, nskb);
41 unsigned int hdr_len = (skb_transport_offset(skb)
42 + sizeof(struct tcphdr));
43 if (pskb_may_pull(skb, min(hdr_len, skb->len)))
50 static struct sk_buff *vlan_pull_tag(struct sk_buff *skb)
52 struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
55 /* Verify we were given a vlan packet */
56 if (vh->h_vlan_proto != htons(ETH_P_8021Q) || skb->len < VLAN_ETH_HLEN)
59 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE)
60 skb->csum = csum_sub(skb->csum, csum_partial(skb->data
61 + ETH_HLEN, VLAN_HLEN, 0));
63 memmove(skb->data + VLAN_HLEN, skb->data, 2 * VLAN_ETH_ALEN);
65 eh = (struct ethhdr *)skb_pull(skb, VLAN_HLEN);
67 skb->protocol = eh->h_proto;
68 skb->mac_header += VLAN_HLEN;
73 static struct sk_buff *modify_vlan_tci(struct datapath *dp, struct sk_buff *skb,
74 const struct odp_flow_key *key,
75 const union odp_action *a, int n_actions)
77 __be16 tci = a->dl_tci.tci;
79 skb = make_writable(skb, VLAN_HLEN);
81 return ERR_PTR(-ENOMEM);
83 if (skb->protocol == htons(ETH_P_8021Q)) {
84 /* Modify vlan id, but maintain other TCI values */
85 struct vlan_ethhdr *vh;
88 if (skb->len < VLAN_ETH_HLEN)
91 vh = vlan_eth_hdr(skb);
92 old_tci = vh->h_vlan_TCI;
96 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE) {
97 __be16 diff[] = { ~old_tci, vh->h_vlan_TCI };
99 skb->csum = ~csum_partial((char *)diff, sizeof(diff),
105 /* Add vlan header */
107 /* Set up checksumming pointers for checksum-deferred packets
108 * on Xen. Otherwise, dev_queue_xmit() will try to do this
109 * when we send the packet out on the wire, and it will fail at
110 * that point because skb_checksum_setup() will not look inside
111 * an 802.1Q header. */
112 err = vswitch_skb_checksum_setup(skb);
118 /* GSO is not implemented for packets with an 802.1Q header, so
119 * we have to do segmentation before we add that header.
121 * GSO does work with hardware-accelerated VLAN tagging, but we
122 * can't use hardware-accelerated VLAN tagging since it
123 * requires the device to have a VLAN group configured (with
124 * e.g. vconfig(8)) and we don't do that.
126 * Having to do this here may be a performance loss, since we
127 * can't take advantage of TSO hardware support, although it
128 * does not make a measurable network performance difference
129 * for 1G Ethernet. Fixing that would require patching the
130 * kernel (either to add GSO support to the VLAN protocol or to
131 * support hardware-accelerated VLAN tagging without VLAN
132 * groups configured). */
133 if (skb_is_gso(skb)) {
134 struct sk_buff *segs;
136 segs = skb_gso_segment(skb, 0);
138 if (unlikely(IS_ERR(segs)))
139 return ERR_CAST(segs);
142 struct sk_buff *nskb = segs->next;
147 /* GSO can change the checksum type so update.*/
148 compute_ip_summed(segs, true);
150 segs = __vlan_put_tag(segs, ntohs(tci));
153 err = execute_actions(dp, segs,
159 while ((segs = nskb)) {
168 } while (segs->next);
171 compute_ip_summed(skb, true);
174 /* The hardware-accelerated version of vlan_put_tag() works
175 * only for a device that has a VLAN group configured (with
176 * e.g. vconfig(8)), so call the software-only version
177 * __vlan_put_tag() directly instead.
179 skb = __vlan_put_tag(skb, ntohs(tci));
181 return ERR_PTR(-ENOMEM);
183 /* GSO doesn't fix up the hardware computed checksum so this
184 * will only be hit in the non-GSO case. */
185 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE)
186 skb->csum = csum_add(skb->csum, csum_partial(skb->data
187 + ETH_HLEN, VLAN_HLEN, 0));
193 static struct sk_buff *strip_vlan(struct sk_buff *skb)
195 skb = make_writable(skb, 0);
201 static struct sk_buff *set_dl_addr(struct sk_buff *skb,
202 const struct odp_action_dl_addr *a)
204 skb = make_writable(skb, 0);
206 struct ethhdr *eh = eth_hdr(skb);
207 if (a->type == ODPAT_SET_DL_SRC)
208 memcpy(eh->h_source, a->dl_addr, ETH_ALEN);
210 memcpy(eh->h_dest, a->dl_addr, ETH_ALEN);
215 /* Updates 'sum', which is a field in 'skb''s data, given that a 4-byte field
216 * covered by the sum has been changed from 'from' to 'to'. If set,
217 * 'pseudohdr' indicates that the field is in the TCP or UDP pseudo-header.
218 * Based on nf_proto_csum_replace4. */
219 static void update_csum(__sum16 *sum, struct sk_buff *skb,
220 __be32 from, __be32 to, int pseudohdr)
222 __be32 diff[] = { ~from, to };
224 if (OVS_CB(skb)->ip_summed != OVS_CSUM_PARTIAL) {
225 *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
226 ~csum_unfold(*sum)));
227 if (OVS_CB(skb)->ip_summed == OVS_CSUM_COMPLETE && pseudohdr)
228 skb->csum = ~csum_partial((char *)diff, sizeof(diff),
230 } else if (pseudohdr)
231 *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
235 static bool is_ip(struct sk_buff *skb, const struct odp_flow_key *key)
237 return (key->dl_type == htons(ETH_P_IP) &&
238 skb->transport_header > skb->network_header);
241 static __sum16 *get_l4_checksum(struct sk_buff *skb, const struct odp_flow_key *key)
243 int transport_len = skb->len - skb_transport_offset(skb);
244 if (key->nw_proto == IPPROTO_TCP) {
245 if (likely(transport_len >= sizeof(struct tcphdr)))
246 return &tcp_hdr(skb)->check;
247 } else if (key->nw_proto == IPPROTO_UDP) {
248 if (likely(transport_len >= sizeof(struct udphdr)))
249 return &udp_hdr(skb)->check;
254 static struct sk_buff *set_nw_addr(struct sk_buff *skb,
255 const struct odp_flow_key *key,
256 const struct odp_action_nw_addr *a)
262 if (unlikely(!is_ip(skb, key)))
265 skb = make_writable(skb, 0);
270 nwaddr = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
272 check = get_l4_checksum(skb, key);
274 update_csum(check, skb, *nwaddr, a->nw_addr, 1);
275 update_csum(&nh->check, skb, *nwaddr, a->nw_addr, 0);
277 *nwaddr = a->nw_addr;
282 static struct sk_buff *set_nw_tos(struct sk_buff *skb,
283 const struct odp_flow_key *key,
284 const struct odp_action_nw_tos *a)
286 if (unlikely(!is_ip(skb, key)))
289 skb = make_writable(skb, 0);
291 struct iphdr *nh = ip_hdr(skb);
296 /* Set the DSCP bits and preserve the ECN bits. */
297 new = a->nw_tos | (nh->tos & INET_ECN_MASK);
298 update_csum(&nh->check, skb, htons((u16)old),
305 static struct sk_buff *set_tp_port(struct sk_buff *skb,
306 const struct odp_flow_key *key,
307 const struct odp_action_tp_port *a)
313 if (unlikely(!is_ip(skb, key)))
316 skb = make_writable(skb, 0);
320 /* Must follow make_writable() since that can move the skb data. */
321 check = get_l4_checksum(skb, key);
322 if (unlikely(!check))
326 * Update port and checksum.
328 * This is OK because source and destination port numbers are at the
329 * same offsets in both UDP and TCP headers, and get_l4_checksum() only
330 * supports those protocols.
333 port = a->type == ODPAT_SET_TP_SRC ? &th->source : &th->dest;
334 update_csum(check, skb, *port, a->tp_port, 0);
341 * is_spoofed_arp - check for invalid ARP packet
343 * @skb: skbuff containing an Ethernet packet, with network header pointing
344 * just past the Ethernet and optional 802.1Q header.
345 * @key: flow key extracted from @skb by flow_extract()
347 * Returns true if @skb is an invalid Ethernet+IPv4 ARP packet: one with screwy
348 * or truncated header fields or one whose inner and outer Ethernet address
351 static bool is_spoofed_arp(struct sk_buff *skb, const struct odp_flow_key *key)
353 struct arp_eth_header *arp;
355 if (key->dl_type != htons(ETH_P_ARP))
358 if (skb_network_offset(skb) + sizeof(struct arp_eth_header) > skb->len)
361 arp = (struct arp_eth_header *)skb_network_header(skb);
362 return (arp->ar_hrd != htons(ARPHRD_ETHER) ||
363 arp->ar_pro != htons(ETH_P_IP) ||
364 arp->ar_hln != ETH_ALEN ||
366 compare_ether_addr(arp->ar_sha, eth_hdr(skb)->h_source));
369 static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
376 p = rcu_dereference(dp->ports[out_port]);
380 vport_send(p->vport, skb);
387 static int output_control(struct datapath *dp, struct sk_buff *skb, u32 arg)
389 skb = skb_clone(skb, GFP_ATOMIC);
392 return dp_output_control(dp, skb, _ODPL_ACTION_NR, arg);
395 /* Send a copy of this packet up to the sFlow agent, along with extra
396 * information about what happened to it. */
397 static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
398 const union odp_action *a, int n_actions,
399 struct dp_port *dp_port)
401 struct odp_sflow_sample_header *hdr;
402 unsigned int actlen = n_actions * sizeof(union odp_action);
403 unsigned int hdrlen = sizeof(struct odp_sflow_sample_header);
404 struct sk_buff *nskb;
406 nskb = skb_copy_expand(skb, actlen + hdrlen, 0, GFP_ATOMIC);
410 memcpy(__skb_push(nskb, actlen), a, actlen);
411 hdr = (struct odp_sflow_sample_header*)__skb_push(nskb, hdrlen);
412 hdr->n_actions = n_actions;
413 hdr->sample_pool = atomic_read(&dp_port->sflow_pool);
414 dp_output_control(dp, nskb, _ODPL_SFLOW_NR, 0);
417 /* Execute a list of actions against 'skb'. */
418 int execute_actions(struct datapath *dp, struct sk_buff *skb,
419 const struct odp_flow_key *key,
420 const union odp_action *a, int n_actions)
422 /* Every output action needs a separate clone of 'skb', but the common
423 * case is just a single output action, so that doing a clone and
424 * then freeing the original skbuff is wasteful. So the following code
425 * is slightly obscure just to avoid that. */
427 u32 priority = skb->priority;
430 if (dp->sflow_probability) {
431 struct dp_port *p = OVS_CB(skb)->dp_port;
433 atomic_inc(&p->sflow_pool);
434 if (dp->sflow_probability == UINT_MAX ||
435 net_random() < dp->sflow_probability)
436 sflow_sample(dp, skb, a, n_actions, p);
440 OVS_CB(skb)->tun_id = 0;
442 for (; n_actions > 0; a++, n_actions--) {
443 if (prev_port != -1) {
444 do_output(dp, skb_clone(skb, GFP_ATOMIC), prev_port);
450 prev_port = a->output.port;
453 case ODPAT_CONTROLLER:
454 err = output_control(dp, skb, a->controller.arg);
461 case ODPAT_SET_TUNNEL:
462 OVS_CB(skb)->tun_id = a->tunnel.tun_id;
465 case ODPAT_SET_DL_TCI:
466 skb = modify_vlan_tci(dp, skb, key, a, n_actions);
471 case ODPAT_STRIP_VLAN:
472 skb = strip_vlan(skb);
475 case ODPAT_SET_DL_SRC:
476 case ODPAT_SET_DL_DST:
477 skb = set_dl_addr(skb, &a->dl_addr);
480 case ODPAT_SET_NW_SRC:
481 case ODPAT_SET_NW_DST:
482 skb = set_nw_addr(skb, key, &a->nw_addr);
485 case ODPAT_SET_NW_TOS:
486 skb = set_nw_tos(skb, key, &a->nw_tos);
489 case ODPAT_SET_TP_SRC:
490 case ODPAT_SET_TP_DST:
491 skb = set_tp_port(skb, key, &a->tp_port);
494 case ODPAT_SET_PRIORITY:
495 skb->priority = a->priority.priority;
498 case ODPAT_POP_PRIORITY:
499 skb->priority = priority;
502 case ODPAT_DROP_SPOOFED_ARP:
503 if (unlikely(is_spoofed_arp(skb, key)))
512 do_output(dp, skb, prev_port);