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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  SR-IPv6 implementation
0004  *
0005  *  Author:
0006  *  David Lebrun <david.lebrun@uclouvain.be>
0007  */
0008 
0009 #include <linux/types.h>
0010 #include <linux/skbuff.h>
0011 #include <linux/net.h>
0012 #include <linux/module.h>
0013 #include <net/ip.h>
0014 #include <net/ip_tunnels.h>
0015 #include <net/lwtunnel.h>
0016 #include <net/netevent.h>
0017 #include <net/netns/generic.h>
0018 #include <net/ip6_fib.h>
0019 #include <net/route.h>
0020 #include <net/seg6.h>
0021 #include <linux/seg6.h>
0022 #include <linux/seg6_iptunnel.h>
0023 #include <net/addrconf.h>
0024 #include <net/ip6_route.h>
0025 #include <net/dst_cache.h>
0026 #ifdef CONFIG_IPV6_SEG6_HMAC
0027 #include <net/seg6_hmac.h>
0028 #endif
0029 #include <linux/netfilter.h>
0030 
0031 static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
0032 {
0033     int head = 0;
0034 
0035     switch (tuninfo->mode) {
0036     case SEG6_IPTUN_MODE_INLINE:
0037         break;
0038     case SEG6_IPTUN_MODE_ENCAP:
0039     case SEG6_IPTUN_MODE_ENCAP_RED:
0040         head = sizeof(struct ipv6hdr);
0041         break;
0042     case SEG6_IPTUN_MODE_L2ENCAP:
0043     case SEG6_IPTUN_MODE_L2ENCAP_RED:
0044         return 0;
0045     }
0046 
0047     return ((tuninfo->srh->hdrlen + 1) << 3) + head;
0048 }
0049 
0050 struct seg6_lwt {
0051     struct dst_cache cache;
0052     struct seg6_iptunnel_encap tuninfo[];
0053 };
0054 
0055 static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
0056 {
0057     return (struct seg6_lwt *)lwt->data;
0058 }
0059 
0060 static inline struct seg6_iptunnel_encap *
0061 seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
0062 {
0063     return seg6_lwt_lwtunnel(lwt)->tuninfo;
0064 }
0065 
0066 static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
0067     [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
0068 };
0069 
0070 static int nla_put_srh(struct sk_buff *skb, int attrtype,
0071                struct seg6_iptunnel_encap *tuninfo)
0072 {
0073     struct seg6_iptunnel_encap *data;
0074     struct nlattr *nla;
0075     int len;
0076 
0077     len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
0078 
0079     nla = nla_reserve(skb, attrtype, len);
0080     if (!nla)
0081         return -EMSGSIZE;
0082 
0083     data = nla_data(nla);
0084     memcpy(data, tuninfo, len);
0085 
0086     return 0;
0087 }
0088 
0089 static void set_tun_src(struct net *net, struct net_device *dev,
0090             struct in6_addr *daddr, struct in6_addr *saddr)
0091 {
0092     struct seg6_pernet_data *sdata = seg6_pernet(net);
0093     struct in6_addr *tun_src;
0094 
0095     rcu_read_lock();
0096 
0097     tun_src = rcu_dereference(sdata->tun_src);
0098 
0099     if (!ipv6_addr_any(tun_src)) {
0100         memcpy(saddr, tun_src, sizeof(struct in6_addr));
0101     } else {
0102         ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
0103                    saddr);
0104     }
0105 
0106     rcu_read_unlock();
0107 }
0108 
0109 /* Compute flowlabel for outer IPv6 header */
0110 static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
0111                   struct ipv6hdr *inner_hdr)
0112 {
0113     int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
0114     __be32 flowlabel = 0;
0115     u32 hash;
0116 
0117     if (do_flowlabel > 0) {
0118         hash = skb_get_hash(skb);
0119         hash = rol32(hash, 16);
0120         flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
0121     } else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
0122         flowlabel = ip6_flowlabel(inner_hdr);
0123     }
0124     return flowlabel;
0125 }
0126 
0127 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
0128 int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
0129 {
0130     struct dst_entry *dst = skb_dst(skb);
0131     struct net *net = dev_net(dst->dev);
0132     struct ipv6hdr *hdr, *inner_hdr;
0133     struct ipv6_sr_hdr *isrh;
0134     int hdrlen, tot_len, err;
0135     __be32 flowlabel;
0136 
0137     hdrlen = (osrh->hdrlen + 1) << 3;
0138     tot_len = hdrlen + sizeof(*hdr);
0139 
0140     err = skb_cow_head(skb, tot_len + skb->mac_len);
0141     if (unlikely(err))
0142         return err;
0143 
0144     inner_hdr = ipv6_hdr(skb);
0145     flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
0146 
0147     skb_push(skb, tot_len);
0148     skb_reset_network_header(skb);
0149     skb_mac_header_rebuild(skb);
0150     hdr = ipv6_hdr(skb);
0151 
0152     /* inherit tc, flowlabel and hlim
0153      * hlim will be decremented in ip6_forward() afterwards and
0154      * decapsulation will overwrite inner hlim with outer hlim
0155      */
0156 
0157     if (skb->protocol == htons(ETH_P_IPV6)) {
0158         ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
0159                  flowlabel);
0160         hdr->hop_limit = inner_hdr->hop_limit;
0161     } else {
0162         ip6_flow_hdr(hdr, 0, flowlabel);
0163         hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
0164 
0165         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
0166 
0167         /* the control block has been erased, so we have to set the
0168          * iif once again.
0169          * We read the receiving interface index directly from the
0170          * skb->skb_iif as it is done in the IPv4 receiving path (i.e.:
0171          * ip_rcv_core(...)).
0172          */
0173         IP6CB(skb)->iif = skb->skb_iif;
0174     }
0175 
0176     hdr->nexthdr = NEXTHDR_ROUTING;
0177 
0178     isrh = (void *)hdr + sizeof(*hdr);
0179     memcpy(isrh, osrh, hdrlen);
0180 
0181     isrh->nexthdr = proto;
0182 
0183     hdr->daddr = isrh->segments[isrh->first_segment];
0184     set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
0185 
0186 #ifdef CONFIG_IPV6_SEG6_HMAC
0187     if (sr_has_hmac(isrh)) {
0188         err = seg6_push_hmac(net, &hdr->saddr, isrh);
0189         if (unlikely(err))
0190             return err;
0191     }
0192 #endif
0193 
0194     hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
0195 
0196     skb_postpush_rcsum(skb, hdr, tot_len);
0197 
0198     return 0;
0199 }
0200 EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
0201 
0202 /* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH */
0203 static int seg6_do_srh_encap_red(struct sk_buff *skb,
0204                  struct ipv6_sr_hdr *osrh, int proto)
0205 {
0206     __u8 first_seg = osrh->first_segment;
0207     struct dst_entry *dst = skb_dst(skb);
0208     struct net *net = dev_net(dst->dev);
0209     struct ipv6hdr *hdr, *inner_hdr;
0210     int hdrlen = ipv6_optlen(osrh);
0211     int red_tlv_offset, tlv_offset;
0212     struct ipv6_sr_hdr *isrh;
0213     bool skip_srh = false;
0214     __be32 flowlabel;
0215     int tot_len, err;
0216     int red_hdrlen;
0217     int tlvs_len;
0218 
0219     if (first_seg > 0) {
0220         red_hdrlen = hdrlen - sizeof(struct in6_addr);
0221     } else {
0222         /* NOTE: if tag/flags and/or other TLVs are introduced in the
0223          * seg6_iptunnel infrastructure, they should be considered when
0224          * deciding to skip the SRH.
0225          */
0226         skip_srh = !sr_has_hmac(osrh);
0227 
0228         red_hdrlen = skip_srh ? 0 : hdrlen;
0229     }
0230 
0231     tot_len = red_hdrlen + sizeof(struct ipv6hdr);
0232 
0233     err = skb_cow_head(skb, tot_len + skb->mac_len);
0234     if (unlikely(err))
0235         return err;
0236 
0237     inner_hdr = ipv6_hdr(skb);
0238     flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
0239 
0240     skb_push(skb, tot_len);
0241     skb_reset_network_header(skb);
0242     skb_mac_header_rebuild(skb);
0243     hdr = ipv6_hdr(skb);
0244 
0245     /* based on seg6_do_srh_encap() */
0246     if (skb->protocol == htons(ETH_P_IPV6)) {
0247         ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
0248                  flowlabel);
0249         hdr->hop_limit = inner_hdr->hop_limit;
0250     } else {
0251         ip6_flow_hdr(hdr, 0, flowlabel);
0252         hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
0253 
0254         memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
0255         IP6CB(skb)->iif = skb->skb_iif;
0256     }
0257 
0258     /* no matter if we have to skip the SRH or not, the first segment
0259      * always comes in the pushed IPv6 header.
0260      */
0261     hdr->daddr = osrh->segments[first_seg];
0262 
0263     if (skip_srh) {
0264         hdr->nexthdr = proto;
0265 
0266         set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
0267         goto out;
0268     }
0269 
0270     /* we cannot skip the SRH, slow path */
0271 
0272     hdr->nexthdr = NEXTHDR_ROUTING;
0273     isrh = (void *)hdr + sizeof(struct ipv6hdr);
0274 
0275     if (unlikely(!first_seg)) {
0276         /* this is a very rare case; we have only one SID but
0277          * we cannot skip the SRH since we are carrying some
0278          * other info.
0279          */
0280         memcpy(isrh, osrh, hdrlen);
0281         goto srcaddr;
0282     }
0283 
0284     tlv_offset = sizeof(*osrh) + (first_seg + 1) * sizeof(struct in6_addr);
0285     red_tlv_offset = tlv_offset - sizeof(struct in6_addr);
0286 
0287     memcpy(isrh, osrh, red_tlv_offset);
0288 
0289     tlvs_len = hdrlen - tlv_offset;
0290     if (unlikely(tlvs_len > 0)) {
0291         const void *s = (const void *)osrh + tlv_offset;
0292         void *d = (void *)isrh + red_tlv_offset;
0293 
0294         memcpy(d, s, tlvs_len);
0295     }
0296 
0297     --isrh->first_segment;
0298     isrh->hdrlen -= 2;
0299 
0300 srcaddr:
0301     isrh->nexthdr = proto;
0302     set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
0303 
0304 #ifdef CONFIG_IPV6_SEG6_HMAC
0305     if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
0306         err = seg6_push_hmac(net, &hdr->saddr, isrh);
0307         if (unlikely(err))
0308             return err;
0309     }
0310 #endif
0311 
0312 out:
0313     hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
0314 
0315     skb_postpush_rcsum(skb, hdr, tot_len);
0316 
0317     return 0;
0318 }
0319 
0320 /* insert an SRH within an IPv6 packet, just after the IPv6 header */
0321 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
0322 {
0323     struct ipv6hdr *hdr, *oldhdr;
0324     struct ipv6_sr_hdr *isrh;
0325     int hdrlen, err;
0326 
0327     hdrlen = (osrh->hdrlen + 1) << 3;
0328 
0329     err = skb_cow_head(skb, hdrlen + skb->mac_len);
0330     if (unlikely(err))
0331         return err;
0332 
0333     oldhdr = ipv6_hdr(skb);
0334 
0335     skb_pull(skb, sizeof(struct ipv6hdr));
0336     skb_postpull_rcsum(skb, skb_network_header(skb),
0337                sizeof(struct ipv6hdr));
0338 
0339     skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
0340     skb_reset_network_header(skb);
0341     skb_mac_header_rebuild(skb);
0342 
0343     hdr = ipv6_hdr(skb);
0344 
0345     memmove(hdr, oldhdr, sizeof(*hdr));
0346 
0347     isrh = (void *)hdr + sizeof(*hdr);
0348     memcpy(isrh, osrh, hdrlen);
0349 
0350     isrh->nexthdr = hdr->nexthdr;
0351     hdr->nexthdr = NEXTHDR_ROUTING;
0352 
0353     isrh->segments[0] = hdr->daddr;
0354     hdr->daddr = isrh->segments[isrh->first_segment];
0355 
0356 #ifdef CONFIG_IPV6_SEG6_HMAC
0357     if (sr_has_hmac(isrh)) {
0358         struct net *net = dev_net(skb_dst(skb)->dev);
0359 
0360         err = seg6_push_hmac(net, &hdr->saddr, isrh);
0361         if (unlikely(err))
0362             return err;
0363     }
0364 #endif
0365 
0366     hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
0367 
0368     skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
0369 
0370     return 0;
0371 }
0372 EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
0373 
0374 static int seg6_do_srh(struct sk_buff *skb)
0375 {
0376     struct dst_entry *dst = skb_dst(skb);
0377     struct seg6_iptunnel_encap *tinfo;
0378     int proto, err = 0;
0379 
0380     tinfo = seg6_encap_lwtunnel(dst->lwtstate);
0381 
0382     switch (tinfo->mode) {
0383     case SEG6_IPTUN_MODE_INLINE:
0384         if (skb->protocol != htons(ETH_P_IPV6))
0385             return -EINVAL;
0386 
0387         err = seg6_do_srh_inline(skb, tinfo->srh);
0388         if (err)
0389             return err;
0390         break;
0391     case SEG6_IPTUN_MODE_ENCAP:
0392     case SEG6_IPTUN_MODE_ENCAP_RED:
0393         err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
0394         if (err)
0395             return err;
0396 
0397         if (skb->protocol == htons(ETH_P_IPV6))
0398             proto = IPPROTO_IPV6;
0399         else if (skb->protocol == htons(ETH_P_IP))
0400             proto = IPPROTO_IPIP;
0401         else
0402             return -EINVAL;
0403 
0404         if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
0405             err = seg6_do_srh_encap(skb, tinfo->srh, proto);
0406         else
0407             err = seg6_do_srh_encap_red(skb, tinfo->srh, proto);
0408 
0409         if (err)
0410             return err;
0411 
0412         skb_set_inner_transport_header(skb, skb_transport_offset(skb));
0413         skb_set_inner_protocol(skb, skb->protocol);
0414         skb->protocol = htons(ETH_P_IPV6);
0415         break;
0416     case SEG6_IPTUN_MODE_L2ENCAP:
0417     case SEG6_IPTUN_MODE_L2ENCAP_RED:
0418         if (!skb_mac_header_was_set(skb))
0419             return -EINVAL;
0420 
0421         if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
0422             return -ENOMEM;
0423 
0424         skb_mac_header_rebuild(skb);
0425         skb_push(skb, skb->mac_len);
0426 
0427         if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
0428             err = seg6_do_srh_encap(skb, tinfo->srh,
0429                         IPPROTO_ETHERNET);
0430         else
0431             err = seg6_do_srh_encap_red(skb, tinfo->srh,
0432                             IPPROTO_ETHERNET);
0433 
0434         if (err)
0435             return err;
0436 
0437         skb->protocol = htons(ETH_P_IPV6);
0438         break;
0439     }
0440 
0441     skb_set_transport_header(skb, sizeof(struct ipv6hdr));
0442     nf_reset_ct(skb);
0443 
0444     return 0;
0445 }
0446 
0447 static int seg6_input_finish(struct net *net, struct sock *sk,
0448                  struct sk_buff *skb)
0449 {
0450     return dst_input(skb);
0451 }
0452 
0453 static int seg6_input_core(struct net *net, struct sock *sk,
0454                struct sk_buff *skb)
0455 {
0456     struct dst_entry *orig_dst = skb_dst(skb);
0457     struct dst_entry *dst = NULL;
0458     struct seg6_lwt *slwt;
0459     int err;
0460 
0461     err = seg6_do_srh(skb);
0462     if (unlikely(err)) {
0463         kfree_skb(skb);
0464         return err;
0465     }
0466 
0467     slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
0468 
0469     preempt_disable();
0470     dst = dst_cache_get(&slwt->cache);
0471     preempt_enable();
0472 
0473     skb_dst_drop(skb);
0474 
0475     if (!dst) {
0476         ip6_route_input(skb);
0477         dst = skb_dst(skb);
0478         if (!dst->error) {
0479             preempt_disable();
0480             dst_cache_set_ip6(&slwt->cache, dst,
0481                       &ipv6_hdr(skb)->saddr);
0482             preempt_enable();
0483         }
0484     } else {
0485         skb_dst_set(skb, dst);
0486     }
0487 
0488     err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
0489     if (unlikely(err))
0490         return err;
0491 
0492     if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
0493         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
0494                    dev_net(skb->dev), NULL, skb, NULL,
0495                    skb_dst(skb)->dev, seg6_input_finish);
0496 
0497     return seg6_input_finish(dev_net(skb->dev), NULL, skb);
0498 }
0499 
0500 static int seg6_input_nf(struct sk_buff *skb)
0501 {
0502     struct net_device *dev = skb_dst(skb)->dev;
0503     struct net *net = dev_net(skb->dev);
0504 
0505     switch (skb->protocol) {
0506     case htons(ETH_P_IP):
0507         return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, NULL,
0508                    skb, NULL, dev, seg6_input_core);
0509     case htons(ETH_P_IPV6):
0510         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, NULL,
0511                    skb, NULL, dev, seg6_input_core);
0512     }
0513 
0514     return -EINVAL;
0515 }
0516 
0517 static int seg6_input(struct sk_buff *skb)
0518 {
0519     if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
0520         return seg6_input_nf(skb);
0521 
0522     return seg6_input_core(dev_net(skb->dev), NULL, skb);
0523 }
0524 
0525 static int seg6_output_core(struct net *net, struct sock *sk,
0526                 struct sk_buff *skb)
0527 {
0528     struct dst_entry *orig_dst = skb_dst(skb);
0529     struct dst_entry *dst = NULL;
0530     struct seg6_lwt *slwt;
0531     int err;
0532 
0533     err = seg6_do_srh(skb);
0534     if (unlikely(err))
0535         goto drop;
0536 
0537     slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
0538 
0539     preempt_disable();
0540     dst = dst_cache_get(&slwt->cache);
0541     preempt_enable();
0542 
0543     if (unlikely(!dst)) {
0544         struct ipv6hdr *hdr = ipv6_hdr(skb);
0545         struct flowi6 fl6;
0546 
0547         memset(&fl6, 0, sizeof(fl6));
0548         fl6.daddr = hdr->daddr;
0549         fl6.saddr = hdr->saddr;
0550         fl6.flowlabel = ip6_flowinfo(hdr);
0551         fl6.flowi6_mark = skb->mark;
0552         fl6.flowi6_proto = hdr->nexthdr;
0553 
0554         dst = ip6_route_output(net, NULL, &fl6);
0555         if (dst->error) {
0556             err = dst->error;
0557             dst_release(dst);
0558             goto drop;
0559         }
0560 
0561         preempt_disable();
0562         dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
0563         preempt_enable();
0564     }
0565 
0566     skb_dst_drop(skb);
0567     skb_dst_set(skb, dst);
0568 
0569     err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
0570     if (unlikely(err))
0571         goto drop;
0572 
0573     if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
0574         return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, net, sk, skb,
0575                    NULL, skb_dst(skb)->dev, dst_output);
0576 
0577     return dst_output(net, sk, skb);
0578 drop:
0579     kfree_skb(skb);
0580     return err;
0581 }
0582 
0583 static int seg6_output_nf(struct net *net, struct sock *sk, struct sk_buff *skb)
0584 {
0585     struct net_device *dev = skb_dst(skb)->dev;
0586 
0587     switch (skb->protocol) {
0588     case htons(ETH_P_IP):
0589         return NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, net, sk, skb,
0590                    NULL, dev, seg6_output_core);
0591     case htons(ETH_P_IPV6):
0592         return NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING, net, sk, skb,
0593                    NULL, dev, seg6_output_core);
0594     }
0595 
0596     return -EINVAL;
0597 }
0598 
0599 static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
0600 {
0601     if (static_branch_unlikely(&nf_hooks_lwtunnel_enabled))
0602         return seg6_output_nf(net, sk, skb);
0603 
0604     return seg6_output_core(net, sk, skb);
0605 }
0606 
0607 static int seg6_build_state(struct net *net, struct nlattr *nla,
0608                 unsigned int family, const void *cfg,
0609                 struct lwtunnel_state **ts,
0610                 struct netlink_ext_ack *extack)
0611 {
0612     struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
0613     struct seg6_iptunnel_encap *tuninfo;
0614     struct lwtunnel_state *newts;
0615     int tuninfo_len, min_size;
0616     struct seg6_lwt *slwt;
0617     int err;
0618 
0619     if (family != AF_INET && family != AF_INET6)
0620         return -EINVAL;
0621 
0622     err = nla_parse_nested_deprecated(tb, SEG6_IPTUNNEL_MAX, nla,
0623                       seg6_iptunnel_policy, extack);
0624 
0625     if (err < 0)
0626         return err;
0627 
0628     if (!tb[SEG6_IPTUNNEL_SRH])
0629         return -EINVAL;
0630 
0631     tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
0632     tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
0633 
0634     /* tuninfo must contain at least the iptunnel encap structure,
0635      * the SRH and one segment
0636      */
0637     min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
0638            sizeof(struct in6_addr);
0639     if (tuninfo_len < min_size)
0640         return -EINVAL;
0641 
0642     switch (tuninfo->mode) {
0643     case SEG6_IPTUN_MODE_INLINE:
0644         if (family != AF_INET6)
0645             return -EINVAL;
0646 
0647         break;
0648     case SEG6_IPTUN_MODE_ENCAP:
0649         break;
0650     case SEG6_IPTUN_MODE_L2ENCAP:
0651         break;
0652     case SEG6_IPTUN_MODE_ENCAP_RED:
0653         break;
0654     case SEG6_IPTUN_MODE_L2ENCAP_RED:
0655         break;
0656     default:
0657         return -EINVAL;
0658     }
0659 
0660     /* verify that SRH is consistent */
0661     if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo), false))
0662         return -EINVAL;
0663 
0664     newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
0665     if (!newts)
0666         return -ENOMEM;
0667 
0668     slwt = seg6_lwt_lwtunnel(newts);
0669 
0670     err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
0671     if (err) {
0672         kfree(newts);
0673         return err;
0674     }
0675 
0676     memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
0677 
0678     newts->type = LWTUNNEL_ENCAP_SEG6;
0679     newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
0680 
0681     if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
0682         newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
0683 
0684     newts->headroom = seg6_lwt_headroom(tuninfo);
0685 
0686     *ts = newts;
0687 
0688     return 0;
0689 }
0690 
0691 static void seg6_destroy_state(struct lwtunnel_state *lwt)
0692 {
0693     dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
0694 }
0695 
0696 static int seg6_fill_encap_info(struct sk_buff *skb,
0697                 struct lwtunnel_state *lwtstate)
0698 {
0699     struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
0700 
0701     if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
0702         return -EMSGSIZE;
0703 
0704     return 0;
0705 }
0706 
0707 static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
0708 {
0709     struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
0710 
0711     return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
0712 }
0713 
0714 static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
0715 {
0716     struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
0717     struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
0718     int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
0719 
0720     if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
0721         return 1;
0722 
0723     return memcmp(a_hdr, b_hdr, len);
0724 }
0725 
0726 static const struct lwtunnel_encap_ops seg6_iptun_ops = {
0727     .build_state = seg6_build_state,
0728     .destroy_state = seg6_destroy_state,
0729     .output = seg6_output,
0730     .input = seg6_input,
0731     .fill_encap = seg6_fill_encap_info,
0732     .get_encap_size = seg6_encap_nlsize,
0733     .cmp_encap = seg6_encap_cmp,
0734     .owner = THIS_MODULE,
0735 };
0736 
0737 int __init seg6_iptunnel_init(void)
0738 {
0739     return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
0740 }
0741 
0742 void seg6_iptunnel_exit(void)
0743 {
0744     lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
0745 }
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