Merge "master" into "next".

[mirror_ovs.git] / datapath / actions.c

/*
 * Distributed under the terms of the GNU GPL version 2.
 * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
 *
 * Significant portions of this file may be copied from parts of the Linux
 * kernel, by Linus Torvalds and others.
 */

/* Functions for executing flow actions. */

#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/in6.h>
#include <linux/if_vlan.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/checksum.h>
#include "datapath.h"
#include "dp_dev.h"
#include "actions.h"
#include "openvswitch/datapath-protocol.h"

static struct sk_buff *
make_writable(struct sk_buff *skb, unsigned min_headroom, gfp_t gfp)
{
        if (skb_shared(skb) || skb_cloned(skb)) {
                struct sk_buff *nskb;
                unsigned headroom = max(min_headroom, skb_headroom(skb));

                nskb = skb_copy_expand(skb, headroom, skb_tailroom(skb), gfp);
                if (nskb) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
                        /* Before 2.6.24 these fields were not copied when
                         * doing an skb_copy_expand. */
                        nskb->ip_summed = skb->ip_summed;
                        nskb->csum = skb->csum;
#endif
#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
                        /* These fields are copied in skb_clone but not in
                         * skb_copy or related functions.  We need to manually
                         * copy them over here. */
                        nskb->proto_data_valid = skb->proto_data_valid;
                        nskb->proto_csum_blank = skb->proto_csum_blank;
#endif
                        kfree_skb(skb);
                        return nskb;
                }
        } else {
                unsigned int hdr_len = (skb_transport_offset(skb)
                                        + sizeof(struct tcphdr));
                if (pskb_may_pull(skb, min(hdr_len, skb->len)))
                        return skb;
        }
        kfree_skb(skb);
        return NULL;
}


static struct sk_buff *
vlan_pull_tag(struct sk_buff *skb)
{
        struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
        struct ethhdr *eh;


        /* Verify we were given a vlan packet */
        if (vh->h_vlan_proto != htons(ETH_P_8021Q))
                return skb;

        memmove(skb->data + VLAN_HLEN, skb->data, 2 * VLAN_ETH_ALEN);

        eh = (struct ethhdr *)skb_pull(skb, VLAN_HLEN);

        skb->protocol = eh->h_proto;
        skb->mac_header += VLAN_HLEN;

        return skb;
}


static struct sk_buff *
modify_vlan_tci(struct datapath *dp, struct sk_buff *skb,
                struct odp_flow_key *key, const union odp_action *a,
                int n_actions, gfp_t gfp)
{
        u16 tci, mask;

        if (a->type == ODPAT_SET_VLAN_VID) {
                tci = ntohs(a->vlan_vid.vlan_vid);
                mask = VLAN_VID_MASK;
                key->dl_vlan = htons(tci & mask);
        } else {
                tci = a->vlan_pcp.vlan_pcp << VLAN_PCP_SHIFT;
                mask = VLAN_PCP_MASK;
        }

        skb = make_writable(skb, VLAN_HLEN, gfp);
        if (!skb)
                return ERR_PTR(-ENOMEM);

        if (skb->protocol == htons(ETH_P_8021Q)) {
                /* Modify vlan id, but maintain other TCI values */
                struct vlan_ethhdr *vh = vlan_eth_hdr(skb);
                vh->h_vlan_TCI = htons((ntohs(vh->h_vlan_TCI) & ~mask) | tci);
        } else {
                /* Add vlan header */

                /* Set up checksumming pointers for checksum-deferred packets
                 * on Xen.  Otherwise, dev_queue_xmit() will try to do this
                 * when we send the packet out on the wire, and it will fail at
                 * that point because skb_checksum_setup() will not look inside
                 * an 802.1Q header. */
                vswitch_skb_checksum_setup(skb);

                /* GSO is not implemented for packets with an 802.1Q header, so
                 * we have to do segmentation before we add that header.
                 *
                 * GSO does work with hardware-accelerated VLAN tagging, but we
                 * can't use hardware-accelerated VLAN tagging since it
                 * requires the device to have a VLAN group configured (with
                 * e.g. vconfig(8)) and we don't do that.
                 *
                 * Having to do this here may be a performance loss, since we
                 * can't take advantage of TSO hardware support, although it
                 * does not make a measurable network performance difference
                 * for 1G Ethernet.  Fixing that would require patching the
                 * kernel (either to add GSO support to the VLAN protocol or to
                 * support hardware-accelerated VLAN tagging without VLAN
                 * groups configured). */
                if (skb_is_gso(skb)) {
                        struct sk_buff *segs;

                        segs = skb_gso_segment(skb, 0);
                        kfree_skb(skb);
                        if (unlikely(IS_ERR(segs)))
                                return ERR_CAST(segs);

                        do {
                                struct sk_buff *nskb = segs->next;
                                int err;

                                segs->next = NULL;

                                segs = __vlan_put_tag(segs, tci);
                                err = -ENOMEM;
                                if (segs) {
                                        struct odp_flow_key segkey = *key;
                                        err = execute_actions(dp, segs,
                                                              &segkey, a + 1,
                                                              n_actions - 1,
                                                              gfp);
                                }

                                if (unlikely(err)) {
                                        while ((segs = nskb)) {
                                                nskb = segs->next;
                                                segs->next = NULL;
                                                kfree_skb(segs);
                                        }
                                        return ERR_PTR(err);
                                }

                                segs = nskb;
                        } while (segs->next);

                        skb = segs;
                }

                /* The hardware-accelerated version of vlan_put_tag() works
                 * only for a device that has a VLAN group configured (with
                 * e.g. vconfig(8)), so call the software-only version
                 * __vlan_put_tag() directly instead.
                 */
                skb = __vlan_put_tag(skb, tci);
                if (!skb)
                        return ERR_PTR(-ENOMEM);
        }

        return skb;
}

static struct sk_buff *strip_vlan(struct sk_buff *skb,
                                  struct odp_flow_key *key, gfp_t gfp)
{
        skb = make_writable(skb, 0, gfp);
        if (skb) {
                vlan_pull_tag(skb);
                key->dl_vlan = htons(ODP_VLAN_NONE);
        }
        return skb;
}

static struct sk_buff *set_dl_addr(struct sk_buff *skb,
                                   const struct odp_action_dl_addr *a,
                                   gfp_t gfp)
{
        skb = make_writable(skb, 0, gfp);
        if (skb) {
                struct ethhdr *eh = eth_hdr(skb);
                memcpy(a->type == ODPAT_SET_DL_SRC ? eh->h_source : eh->h_dest,
                       a->dl_addr, ETH_ALEN);
        }
        return skb;
}

/* Updates 'sum', which is a field in 'skb''s data, given that a 4-byte field
 * covered by the sum has been changed from 'from' to 'to'.  If set,
 * 'pseudohdr' indicates that the field is in the TCP or UDP pseudo-header.
 * Based on nf_proto_csum_replace4. */
static void update_csum(__sum16 *sum, struct sk_buff *skb,
                        __be32 from, __be32 to, int pseudohdr)
{
        __be32 diff[] = { ~from, to };

/* On older kernels, CHECKSUM_PARTIAL and CHECKSUM_COMPLETE are both defined
 * as CHECKSUM_HW.  However, we can make some inferences so that we can update
 * the checksums appropriately. */
        enum {
                CSUM_PARTIAL,   /* Partial checksum, skb->csum undefined. */
                CSUM_PACKET,    /* In-packet checksum, skb->csum undefined. */
                CSUM_COMPLETE,  /* In-packet checksum, skb->csum valid. */
        } csum_type;

        csum_type = CSUM_PACKET;
#ifndef CHECKSUM_HW
        /* Newer kernel, just map between kernel types and ours. */
        if (skb->ip_summed == CHECKSUM_PARTIAL)
                csum_type = CSUM_PARTIAL;
        else if (skb->ip_summed == CHECKSUM_COMPLETE)
                csum_type = CSUM_COMPLETE;
#else
        /* In theory this could be either CHECKSUM_PARTIAL or CHECKSUM_COMPLETE.
         * However, we should only get CHECKSUM_PARTIAL packets from Xen, which
         * uses some special fields to represent this (see below).  Since we
         * can only make one type work, pick the one that actually happens in
         * practice. */
        if (skb->ip_summed == CHECKSUM_HW)
                csum_type = CSUM_COMPLETE;
#endif
#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
        /* Xen has a special way of representing CHECKSUM_PARTIAL on older
         * kernels. */
        if (skb->proto_csum_blank)
                csum_type = CSUM_PARTIAL;
#endif

        if (csum_type != CSUM_PARTIAL) {
                *sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
                                ~csum_unfold(*sum)));
                if (csum_type == CSUM_COMPLETE && pseudohdr)
                        skb->csum = ~csum_partial((char *)diff, sizeof(diff),
                                                ~skb->csum);
        } else if (pseudohdr)
                *sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
                                csum_unfold(*sum)));
}

static struct sk_buff *set_nw_addr(struct sk_buff *skb,
                                   struct odp_flow_key *key,
                                   const struct odp_action_nw_addr *a,
                                   gfp_t gfp)
{
        if (key->dl_type != htons(ETH_P_IP))
                return skb;

        skb = make_writable(skb, 0, gfp);
        if (skb) {
                struct iphdr *nh = ip_hdr(skb);
                u32 *f = a->type == ODPAT_SET_NW_SRC ? &nh->saddr : &nh->daddr;
                u32 old = *f;
                u32 new = a->nw_addr;

                if (key->nw_proto == IPPROTO_TCP) {
                        struct tcphdr *th = tcp_hdr(skb);
                        update_csum(&th->check, skb, old, new, 1);
                } else if (key->nw_proto == IPPROTO_UDP) {
                        struct udphdr *th = udp_hdr(skb);
                        update_csum(&th->check, skb, old, new, 1);
                }
                update_csum(&nh->check, skb, old, new, 0);
                *f = new;
        }
        return skb;
}

static struct sk_buff *set_nw_tos(struct sk_buff *skb,
                                   struct odp_flow_key *key,
                                   const struct odp_action_nw_tos *a,
                                   gfp_t gfp)
{
        if (key->dl_type != htons(ETH_P_IP))
                return skb;

        skb = make_writable(skb, 0, gfp);
        if (skb) {
                struct iphdr *nh = ip_hdr(skb);
                u8 *f = &nh->tos;
                u8 old = *f;
                u8 new;

                /* Set the DSCP bits and preserve the ECN bits. */
                new = (a->nw_tos & ~INET_ECN_MASK) | (nh->tos & INET_ECN_MASK);
                update_csum(&nh->check, skb, htons((uint16_t)old),
                                htons((uint16_t)new), 0);
                *f = new;
        }
        return skb;
}

static struct sk_buff *
set_tp_port(struct sk_buff *skb, struct odp_flow_key *key,
            const struct odp_action_tp_port *a,
            gfp_t gfp)
{
        int check_ofs;

        if (key->dl_type != htons(ETH_P_IP))
                return skb;

        if (key->nw_proto == IPPROTO_TCP)
                check_ofs = offsetof(struct tcphdr, check);
        else if (key->nw_proto == IPPROTO_UDP)
                check_ofs = offsetof(struct udphdr, check);
        else
                return skb;

        skb = make_writable(skb, 0, gfp);
        if (skb) {
                struct udphdr *th = udp_hdr(skb);
                u16 *f = a->type == ODPAT_SET_TP_SRC ? &th->source : &th->dest;
                u16 old = *f;
                u16 new = a->tp_port;
                update_csum((u16*)(skb_transport_header(skb) + check_ofs), 
                                skb, old, new, 0);
                *f = new;
        }
        return skb;
}

static inline unsigned packet_length(const struct sk_buff *skb)
{
        unsigned length = skb->len - ETH_HLEN;
        if (skb->protocol == htons(ETH_P_8021Q))
                length -= VLAN_HLEN;
        return length;
}

int dp_xmit_skb(struct sk_buff *skb)
{
        struct datapath *dp = skb->dev->br_port->dp;
        int len = skb->len;

        if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) {
                printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
                       dp_name(dp), packet_length(skb), skb->dev->mtu);
                kfree_skb(skb);
                return -E2BIG;
        }

        forward_ip_summed(skb);
        dev_queue_xmit(skb);

        return len;
}

static void
do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
{
        struct net_bridge_port *p;
        struct net_device *dev;

        if (!skb)
                goto error;

        p = dp->ports[out_port];
        if (!p)
                goto error;

        dev = skb->dev = p->dev;
        if (is_dp_dev(dev))
                dp_dev_recv(dev, skb);
        else
                dp_xmit_skb(skb);
        return;

error:
        kfree_skb(skb);
}

/* Never consumes 'skb'.  Returns a port that 'skb' should be sent to, -1 if
 * none.  */
static int output_group(struct datapath *dp, __u16 group,
                        struct sk_buff *skb, gfp_t gfp)
{
        struct dp_port_group *g = rcu_dereference(dp->groups[group]);
        int prev_port = -1;
        int i;

        if (!g)
                return -1;
        for (i = 0; i < g->n_ports; i++) {
                struct net_bridge_port *p = dp->ports[g->ports[i]];
                if (!p || skb->dev == p->dev)
                        continue;
                if (prev_port != -1) {
                        struct sk_buff *clone = skb_clone(skb, gfp);
                        if (!clone)
                                return -1;
                        do_output(dp, clone, prev_port);
                }
                prev_port = p->port_no;
        }
        return prev_port;
}

static int
output_control(struct datapath *dp, struct sk_buff *skb, u32 arg, gfp_t gfp)
{
        skb = skb_clone(skb, gfp);
        if (!skb)
                return -ENOMEM;
        return dp_output_control(dp, skb, _ODPL_ACTION_NR, arg);
}

/* Send a copy of this packet up to the sFlow agent, along with extra
 * information about what happened to it. */
static void sflow_sample(struct datapath *dp, struct sk_buff *skb,
                         const union odp_action *a, int n_actions,
                         gfp_t gfp, struct net_bridge_port *nbp)
{
        struct odp_sflow_sample_header *hdr;
        unsigned int actlen = n_actions * sizeof(union odp_action);
        unsigned int hdrlen = sizeof(struct odp_sflow_sample_header);
        struct sk_buff *nskb;

        nskb = skb_copy_expand(skb, actlen + hdrlen, 0, gfp);
        if (!nskb)
                return;

        memcpy(__skb_push(nskb, actlen), a, actlen);
        hdr = (struct odp_sflow_sample_header*)__skb_push(nskb, hdrlen);
        hdr->n_actions = n_actions;
        hdr->sample_pool = atomic_read(&nbp->sflow_pool);
        dp_output_control(dp, nskb, _ODPL_SFLOW_NR, 0);
}

/* Execute a list of actions against 'skb'. */
int execute_actions(struct datapath *dp, struct sk_buff *skb,
                    struct odp_flow_key *key,
                    const union odp_action *a, int n_actions,
                    gfp_t gfp)
{
        /* Every output action needs a separate clone of 'skb', but the common
         * case is just a single output action, so that doing a clone and
         * then freeing the original skbuff is wasteful.  So the following code
         * is slightly obscure just to avoid that. */
        int prev_port = -1;
        int err;

        if (dp->sflow_probability) {
                struct net_bridge_port *p = skb->dev->br_port;
                if (p) {
                        atomic_inc(&p->sflow_pool);
                        if (dp->sflow_probability == UINT_MAX ||
                            net_random() < dp->sflow_probability)
                                sflow_sample(dp, skb, a, n_actions, gfp, p);
                }
        }

        for (; n_actions > 0; a++, n_actions--) {
                WARN_ON_ONCE(skb_shared(skb));
                if (prev_port != -1) {
                        do_output(dp, skb_clone(skb, gfp), prev_port);
                        prev_port = -1;
                }

                switch (a->type) {
                case ODPAT_OUTPUT:
                        prev_port = a->output.port;
                        break;

                case ODPAT_OUTPUT_GROUP:
                        prev_port = output_group(dp, a->output_group.group,
                                                 skb, gfp);
                        break;

                case ODPAT_CONTROLLER:
                        err = output_control(dp, skb, a->controller.arg, gfp);
                        if (err) {
                                kfree_skb(skb);
                                return err;
                        }
                        break;

                case ODPAT_SET_VLAN_VID:
                case ODPAT_SET_VLAN_PCP:
                        skb = modify_vlan_tci(dp, skb, key, a, n_actions, gfp);
                        if (IS_ERR(skb))
                                return PTR_ERR(skb);
                        break;

                case ODPAT_STRIP_VLAN:
                        skb = strip_vlan(skb, key, gfp);
                        break;

                case ODPAT_SET_DL_SRC:
                case ODPAT_SET_DL_DST:
                        skb = set_dl_addr(skb, &a->dl_addr, gfp);
                        break;

                case ODPAT_SET_NW_SRC:
                case ODPAT_SET_NW_DST:
                        skb = set_nw_addr(skb, key, &a->nw_addr, gfp);
                        break;

                case ODPAT_SET_NW_TOS:
                        skb = set_nw_tos(skb, key, &a->nw_tos, gfp);
                        break;

                case ODPAT_SET_TP_SRC:
                case ODPAT_SET_TP_DST:
                        skb = set_tp_port(skb, key, &a->tp_port, gfp);
                        break;
                }
                if (!skb)
                        return -ENOMEM;
        }
        if (prev_port != -1)
                do_output(dp, skb, prev_port);
        else
                kfree_skb(skb);
        return 0;
}