// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* SR-IPv6 implementation
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*
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* Author:
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* David Lebrun <david.lebrun@uclouvain.be>
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*/
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#include <linux/types.h>
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#include <linux/skbuff.h>
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#include <linux/net.h>
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#include <linux/module.h>
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#include <net/ip.h>
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#include <net/ip_tunnels.h>
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#include <net/lwtunnel.h>
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#include <net/netevent.h>
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#include <net/netns/generic.h>
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#include <net/ip6_fib.h>
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#include <net/route.h>
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#include <net/seg6.h>
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#include <linux/seg6.h>
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#include <linux/seg6_iptunnel.h>
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#include <net/addrconf.h>
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#include <net/ip6_route.h>
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#include <net/dst_cache.h>
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#ifdef CONFIG_IPV6_SEG6_HMAC
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#include <net/seg6_hmac.h>
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#endif
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static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
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{
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int head = 0;
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switch (tuninfo->mode) {
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case SEG6_IPTUN_MODE_INLINE:
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break;
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case SEG6_IPTUN_MODE_ENCAP:
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head = sizeof(struct ipv6hdr);
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break;
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case SEG6_IPTUN_MODE_L2ENCAP:
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return 0;
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}
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return ((tuninfo->srh->hdrlen + 1) << 3) + head;
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}
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struct seg6_lwt {
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struct dst_cache cache;
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struct seg6_iptunnel_encap tuninfo[];
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};
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static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
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{
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return (struct seg6_lwt *)lwt->data;
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}
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static inline struct seg6_iptunnel_encap *
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seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
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{
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return seg6_lwt_lwtunnel(lwt)->tuninfo;
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}
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static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
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[SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
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};
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static int nla_put_srh(struct sk_buff *skb, int attrtype,
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struct seg6_iptunnel_encap *tuninfo)
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{
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struct seg6_iptunnel_encap *data;
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struct nlattr *nla;
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int len;
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len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
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nla = nla_reserve(skb, attrtype, len);
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if (!nla)
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return -EMSGSIZE;
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data = nla_data(nla);
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memcpy(data, tuninfo, len);
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return 0;
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}
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static void set_tun_src(struct net *net, struct net_device *dev,
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struct in6_addr *daddr, struct in6_addr *saddr)
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{
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struct seg6_pernet_data *sdata = seg6_pernet(net);
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struct in6_addr *tun_src;
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rcu_read_lock();
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tun_src = rcu_dereference(sdata->tun_src);
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if (!ipv6_addr_any(tun_src)) {
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memcpy(saddr, tun_src, sizeof(struct in6_addr));
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} else {
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ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
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saddr);
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}
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rcu_read_unlock();
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}
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/* Compute flowlabel for outer IPv6 header */
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static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
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struct ipv6hdr *inner_hdr)
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{
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int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
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__be32 flowlabel = 0;
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u32 hash;
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if (do_flowlabel > 0) {
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hash = skb_get_hash(skb);
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hash = rol32(hash, 16);
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flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
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} else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
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flowlabel = ip6_flowlabel(inner_hdr);
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}
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return flowlabel;
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}
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/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
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int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct net *net = dev_net(dst->dev);
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struct ipv6hdr *hdr, *inner_hdr;
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struct ipv6_sr_hdr *isrh;
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int hdrlen, tot_len, err;
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__be32 flowlabel;
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hdrlen = (osrh->hdrlen + 1) << 3;
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tot_len = hdrlen + sizeof(*hdr);
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err = skb_cow_head(skb, tot_len + skb->mac_len);
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if (unlikely(err))
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return err;
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inner_hdr = ipv6_hdr(skb);
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flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
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skb_push(skb, tot_len);
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skb_reset_network_header(skb);
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skb_mac_header_rebuild(skb);
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hdr = ipv6_hdr(skb);
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/* inherit tc, flowlabel and hlim
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* hlim will be decremented in ip6_forward() afterwards and
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* decapsulation will overwrite inner hlim with outer hlim
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*/
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if (skb->protocol == htons(ETH_P_IPV6)) {
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ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
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flowlabel);
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hdr->hop_limit = inner_hdr->hop_limit;
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} else {
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ip6_flow_hdr(hdr, 0, flowlabel);
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hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
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memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
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/* the control block has been erased, so we have to set the
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* iif once again.
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* We read the receiving interface index directly from the
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* skb->skb_iif as it is done in the IPv4 receiving path (i.e.:
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* ip_rcv_core(...)).
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*/
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IP6CB(skb)->iif = skb->skb_iif;
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}
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hdr->nexthdr = NEXTHDR_ROUTING;
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isrh = (void *)hdr + sizeof(*hdr);
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memcpy(isrh, osrh, hdrlen);
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isrh->nexthdr = proto;
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hdr->daddr = isrh->segments[isrh->first_segment];
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set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
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#ifdef CONFIG_IPV6_SEG6_HMAC
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if (sr_has_hmac(isrh)) {
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err = seg6_push_hmac(net, &hdr->saddr, isrh);
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if (unlikely(err))
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return err;
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}
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#endif
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hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
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skb_postpush_rcsum(skb, hdr, tot_len);
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return 0;
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}
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EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
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/* insert an SRH within an IPv6 packet, just after the IPv6 header */
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int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
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{
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struct ipv6hdr *hdr, *oldhdr;
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struct ipv6_sr_hdr *isrh;
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int hdrlen, err;
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hdrlen = (osrh->hdrlen + 1) << 3;
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err = skb_cow_head(skb, hdrlen + skb->mac_len);
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if (unlikely(err))
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return err;
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oldhdr = ipv6_hdr(skb);
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skb_pull(skb, sizeof(struct ipv6hdr));
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skb_postpull_rcsum(skb, skb_network_header(skb),
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sizeof(struct ipv6hdr));
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skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
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skb_reset_network_header(skb);
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skb_mac_header_rebuild(skb);
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hdr = ipv6_hdr(skb);
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memmove(hdr, oldhdr, sizeof(*hdr));
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isrh = (void *)hdr + sizeof(*hdr);
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memcpy(isrh, osrh, hdrlen);
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isrh->nexthdr = hdr->nexthdr;
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hdr->nexthdr = NEXTHDR_ROUTING;
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isrh->segments[0] = hdr->daddr;
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hdr->daddr = isrh->segments[isrh->first_segment];
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#ifdef CONFIG_IPV6_SEG6_HMAC
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if (sr_has_hmac(isrh)) {
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struct net *net = dev_net(skb_dst(skb)->dev);
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err = seg6_push_hmac(net, &hdr->saddr, isrh);
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if (unlikely(err))
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return err;
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}
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#endif
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hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
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skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
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return 0;
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}
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EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
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static int seg6_do_srh(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct seg6_iptunnel_encap *tinfo;
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int proto, err = 0;
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tinfo = seg6_encap_lwtunnel(dst->lwtstate);
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switch (tinfo->mode) {
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case SEG6_IPTUN_MODE_INLINE:
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if (skb->protocol != htons(ETH_P_IPV6))
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return -EINVAL;
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err = seg6_do_srh_inline(skb, tinfo->srh);
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if (err)
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return err;
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break;
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case SEG6_IPTUN_MODE_ENCAP:
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err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
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if (err)
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return err;
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if (skb->protocol == htons(ETH_P_IPV6))
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proto = IPPROTO_IPV6;
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else if (skb->protocol == htons(ETH_P_IP))
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proto = IPPROTO_IPIP;
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else
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return -EINVAL;
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err = seg6_do_srh_encap(skb, tinfo->srh, proto);
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if (err)
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return err;
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skb_set_inner_transport_header(skb, skb_transport_offset(skb));
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skb_set_inner_protocol(skb, skb->protocol);
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skb->protocol = htons(ETH_P_IPV6);
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break;
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case SEG6_IPTUN_MODE_L2ENCAP:
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if (!skb_mac_header_was_set(skb))
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return -EINVAL;
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if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
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return -ENOMEM;
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skb_mac_header_rebuild(skb);
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skb_push(skb, skb->mac_len);
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err = seg6_do_srh_encap(skb, tinfo->srh, IPPROTO_ETHERNET);
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if (err)
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return err;
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skb->protocol = htons(ETH_P_IPV6);
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break;
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}
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skb_set_transport_header(skb, sizeof(struct ipv6hdr));
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return 0;
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}
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static int seg6_input(struct sk_buff *skb)
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{
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struct dst_entry *orig_dst = skb_dst(skb);
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struct dst_entry *dst = NULL;
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struct seg6_lwt *slwt;
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int err;
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err = seg6_do_srh(skb);
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if (unlikely(err)) {
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kfree_skb(skb);
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return err;
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}
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slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
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preempt_disable();
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dst = dst_cache_get(&slwt->cache);
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preempt_enable();
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skb_dst_drop(skb);
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if (!dst) {
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ip6_route_input(skb);
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dst = skb_dst(skb);
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if (!dst->error) {
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preempt_disable();
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dst_cache_set_ip6(&slwt->cache, dst,
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&ipv6_hdr(skb)->saddr);
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preempt_enable();
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}
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} else {
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skb_dst_set(skb, dst);
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}
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err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
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if (unlikely(err))
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return err;
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return dst_input(skb);
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}
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static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct dst_entry *orig_dst = skb_dst(skb);
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struct dst_entry *dst = NULL;
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struct seg6_lwt *slwt;
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int err = -EINVAL;
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err = seg6_do_srh(skb);
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if (unlikely(err))
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goto drop;
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slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
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preempt_disable();
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dst = dst_cache_get(&slwt->cache);
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preempt_enable();
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if (unlikely(!dst)) {
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struct ipv6hdr *hdr = ipv6_hdr(skb);
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struct flowi6 fl6;
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memset(&fl6, 0, sizeof(fl6));
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fl6.daddr = hdr->daddr;
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fl6.saddr = hdr->saddr;
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fl6.flowlabel = ip6_flowinfo(hdr);
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fl6.flowi6_mark = skb->mark;
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fl6.flowi6_proto = hdr->nexthdr;
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dst = ip6_route_output(net, NULL, &fl6);
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if (dst->error) {
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err = dst->error;
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dst_release(dst);
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goto drop;
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}
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preempt_disable();
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dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
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preempt_enable();
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}
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skb_dst_drop(skb);
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skb_dst_set(skb, dst);
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err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
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if (unlikely(err))
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goto drop;
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return dst_output(net, sk, skb);
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drop:
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kfree_skb(skb);
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return err;
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}
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static int seg6_build_state(struct net *net, struct nlattr *nla,
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unsigned int family, const void *cfg,
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struct lwtunnel_state **ts,
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struct netlink_ext_ack *extack)
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{
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struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
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struct seg6_iptunnel_encap *tuninfo;
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struct lwtunnel_state *newts;
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int tuninfo_len, min_size;
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struct seg6_lwt *slwt;
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int err;
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if (family != AF_INET && family != AF_INET6)
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return -EINVAL;
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err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
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seg6_iptunnel_policy, extack);
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if (err < 0)
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return err;
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if (!tb[SEG6_IPTUNNEL_SRH])
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return -EINVAL;
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tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
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tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
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/* tuninfo must contain at least the iptunnel encap structure,
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* the SRH and one segment
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*/
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min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
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sizeof(struct in6_addr);
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if (tuninfo_len < min_size)
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return -EINVAL;
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switch (tuninfo->mode) {
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case SEG6_IPTUN_MODE_INLINE:
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if (family != AF_INET6)
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return -EINVAL;
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break;
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case SEG6_IPTUN_MODE_ENCAP:
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break;
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case SEG6_IPTUN_MODE_L2ENCAP:
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break;
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default:
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return -EINVAL;
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}
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/* verify that SRH is consistent */
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if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
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return -EINVAL;
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newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
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if (!newts)
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return -ENOMEM;
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slwt = seg6_lwt_lwtunnel(newts);
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err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
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if (err) {
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kfree(newts);
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return err;
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}
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memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
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newts->type = LWTUNNEL_ENCAP_SEG6;
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newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
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if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
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newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
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newts->headroom = seg6_lwt_headroom(tuninfo);
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*ts = newts;
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return 0;
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}
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static void seg6_destroy_state(struct lwtunnel_state *lwt)
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{
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dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
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}
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static int seg6_fill_encap_info(struct sk_buff *skb,
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struct lwtunnel_state *lwtstate)
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{
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struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
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if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
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return -EMSGSIZE;
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return 0;
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}
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static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
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{
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struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
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return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
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}
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static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
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{
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struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
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struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
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int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
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if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
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return 1;
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return memcmp(a_hdr, b_hdr, len);
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}
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static const struct lwtunnel_encap_ops seg6_iptun_ops = {
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.build_state = seg6_build_state,
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.destroy_state = seg6_destroy_state,
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.output = seg6_output,
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.input = seg6_input,
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.fill_encap = seg6_fill_encap_info,
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.get_encap_size = seg6_encap_nlsize,
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.cmp_encap = seg6_encap_cmp,
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.owner = THIS_MODULE,
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};
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int __init seg6_iptunnel_init(void)
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{
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return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
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}
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void seg6_iptunnel_exit(void)
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{
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lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
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}
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