/* * Extension Header handling for IPv6 * Linux INET6 implementation * * Authors: * Pedro Roque * Andi Kleen * Alexey Kuznetsov * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ /* Changes: * yoshfuji : ensure not to overrun while parsing * tlv options. * Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs(). * YOSHIFUJI Hideaki @USAGI Register inbound extension header * handlers as inet6_protocol{}. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if IS_ENABLED(CONFIG_IPV6_MIP6) #include #endif #include /* * Parsing tlv encoded headers. * * Parsing function "func" returns true, if parsing succeed * and false, if it failed. * It MUST NOT touch skb->h. */ struct tlvtype_proc { int type; bool (*func)(struct sk_buff *skb, int offset); }; /********************* Generic functions *********************/ /* An unknown option is detected, decide what to do */ static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff) { switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) { case 0: /* ignore */ return true; case 1: /* drop packet */ break; case 3: /* Send ICMP if not a multicast address and drop packet */ /* Actually, it is redundant check. icmp_send will recheck in any case. */ if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) break; case 2: /* send ICMP PARM PROB regardless and drop packet */ icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff); return false; } kfree_skb(skb); return false; } /* Parse tlv encoded option header (hop-by-hop or destination) */ static bool ip6_parse_tlv(const struct tlvtype_proc *procs, struct sk_buff *skb) { const struct tlvtype_proc *curr; const unsigned char *nh = skb_network_header(skb); int off = skb_network_header_len(skb); int len = (skb_transport_header(skb)[1] + 1) << 3; int padlen = 0; if (skb_transport_offset(skb) + len > skb_headlen(skb)) goto bad; off += 2; len -= 2; while (len > 0) { int optlen = nh[off + 1] + 2; int i; switch (nh[off]) { case IPV6_TLV_PAD1: optlen = 1; padlen++; if (padlen > 7) goto bad; break; case IPV6_TLV_PADN: /* RFC 2460 states that the purpose of PadN is * to align the containing header to multiples * of 8. 7 is therefore the highest valid value. * See also RFC 4942, Section 2.1.9.5. */ padlen += optlen; if (padlen > 7) goto bad; /* RFC 4942 recommends receiving hosts to * actively check PadN payload to contain * only zeroes. */ for (i = 2; i < optlen; i++) { if (nh[off + i] != 0) goto bad; } break; default: /* Other TLV code so scan list */ if (optlen > len) goto bad; for (curr = procs; curr->type >= 0; curr++) { if (curr->type == nh[off]) { /* type specific length/alignment checks will be performed in the func(). */ if (curr->func(skb, off) == false) return false; break; } } if (curr->type < 0) { if (ip6_tlvopt_unknown(skb, off) == 0) return false; } padlen = 0; break; } off += optlen; len -= optlen; } if (len == 0) return true; bad: kfree_skb(skb); return false; } /***************************** Destination options header. *****************************/ #if IS_ENABLED(CONFIG_IPV6_MIP6) static bool ipv6_dest_hao(struct sk_buff *skb, int optoff) { struct ipv6_destopt_hao *hao; struct inet6_skb_parm *opt = IP6CB(skb); struct ipv6hdr *ipv6h = ipv6_hdr(skb); struct in6_addr tmp_addr; int ret; if (opt->dsthao) { net_dbg_ratelimited("hao duplicated\n"); goto discard; } opt->dsthao = opt->dst1; opt->dst1 = 0; hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff); if (hao->length != 16) { net_dbg_ratelimited("hao invalid option length = %d\n", hao->length); goto discard; } if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) { net_dbg_ratelimited("hao is not an unicast addr: %pI6\n", &hao->addr); goto discard; } ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr, (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS); if (unlikely(ret < 0)) goto discard; if (skb_cloned(skb)) { if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) goto discard; /* update all variable using below by copied skbuff */ hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff); ipv6h = ipv6_hdr(skb); } if (skb->ip_summed == CHECKSUM_COMPLETE) skb->ip_summed = CHECKSUM_NONE; tmp_addr = ipv6h->saddr; ipv6h->saddr = hao->addr; hao->addr = tmp_addr; if (skb->tstamp.tv64 == 0) __net_timestamp(skb); return true; discard: kfree_skb(skb); return false; } #endif static const struct tlvtype_proc tlvprocdestopt_lst[] = { #if IS_ENABLED(CONFIG_IPV6_MIP6) { .type = IPV6_TLV_HAO, .func = ipv6_dest_hao, }, #endif {-1, NULL} }; static int ipv6_destopt_rcv(struct sk_buff *skb) { struct inet6_skb_parm *opt = IP6CB(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) __u16 dstbuf; #endif struct dst_entry *dst = skb_dst(skb); if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) || !pskb_may_pull(skb, (skb_transport_offset(skb) + ((skb_transport_header(skb)[1] + 1) << 3)))) { IP6_INC_STATS_BH(dev_net(dst->dev), ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS); kfree_skb(skb); return -1; } opt->lastopt = opt->dst1 = skb_network_header_len(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) dstbuf = opt->dst1; #endif if (ip6_parse_tlv(tlvprocdestopt_lst, skb)) { skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3; opt = IP6CB(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) opt->nhoff = dstbuf; #else opt->nhoff = opt->dst1; #endif return 1; } IP6_INC_STATS_BH(dev_net(dst->dev), ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS); return -1; } /******************************** Routing header. ********************************/ /* called with rcu_read_lock() */ static int ipv6_rthdr_rcv(struct sk_buff *skb) { struct inet6_skb_parm *opt = IP6CB(skb); struct in6_addr *addr = NULL; struct in6_addr daddr; struct inet6_dev *idev; int n, i; struct ipv6_rt_hdr *hdr; struct rt0_hdr *rthdr; struct net *net = dev_net(skb->dev); int accept_source_route = net->ipv6.devconf_all->accept_source_route; idev = __in6_dev_get(skb->dev); if (idev && accept_source_route > idev->cnf.accept_source_route) accept_source_route = idev->cnf.accept_source_route; if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) || !pskb_may_pull(skb, (skb_transport_offset(skb) + ((skb_transport_header(skb)[1] + 1) << 3)))) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); kfree_skb(skb); return -1; } hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb); if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) || skb->pkt_type != PACKET_HOST) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } looped_back: if (hdr->segments_left == 0) { switch (hdr->type) { #if IS_ENABLED(CONFIG_IPV6_MIP6) case IPV6_SRCRT_TYPE_2: /* Silently discard type 2 header unless it was * processed by own */ if (!addr) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } break; #endif default: break; } opt->lastopt = opt->srcrt = skb_network_header_len(skb); skb->transport_header += (hdr->hdrlen + 1) << 3; opt->dst0 = opt->dst1; opt->dst1 = 0; opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb); return 1; } switch (hdr->type) { #if IS_ENABLED(CONFIG_IPV6_MIP6) case IPV6_SRCRT_TYPE_2: if (accept_source_route < 0) goto unknown_rh; /* Silently discard invalid RTH type 2 */ if (hdr->hdrlen != 2 || hdr->segments_left != 1) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); kfree_skb(skb); return -1; } break; #endif default: goto unknown_rh; } /* * This is the routing header forwarding algorithm from * RFC 2460, page 16. */ n = hdr->hdrlen >> 1; if (hdr->segments_left > n) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, ((&hdr->segments_left) - skb_network_header(skb))); return -1; } /* We are about to mangle packet header. Be careful! Do not damage packets queued somewhere. */ if (skb_cloned(skb)) { /* the copy is a forwarded packet */ if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_OUTDISCARDS); kfree_skb(skb); return -1; } hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb); } if (skb->ip_summed == CHECKSUM_COMPLETE) skb->ip_summed = CHECKSUM_NONE; i = n - --hdr->segments_left; rthdr = (struct rt0_hdr *) hdr; addr = rthdr->addr; addr += i - 1; switch (hdr->type) { #if IS_ENABLED(CONFIG_IPV6_MIP6) case IPV6_SRCRT_TYPE_2: if (xfrm6_input_addr(skb, (xfrm_address_t *)addr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr, IPPROTO_ROUTING) < 0) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } break; #endif default: break; } if (ipv6_addr_is_multicast(addr)) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } daddr = *addr; *addr = ipv6_hdr(skb)->daddr; ipv6_hdr(skb)->daddr = daddr; skb_dst_drop(skb); ip6_route_input(skb); if (skb_dst(skb)->error) { skb_push(skb, skb->data - skb_network_header(skb)); dst_input(skb); return -1; } if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) { if (ipv6_hdr(skb)->hop_limit <= 1) { IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0); kfree_skb(skb); return -1; } ipv6_hdr(skb)->hop_limit--; goto looped_back; } skb_push(skb, skb->data - skb_network_header(skb)); dst_input(skb); return -1; unknown_rh: IP6_INC_STATS_BH(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb_network_header(skb)); return -1; } static const struct inet6_protocol rthdr_protocol = { .handler = ipv6_rthdr_rcv, .flags = INET6_PROTO_NOPOLICY, }; static const struct inet6_protocol destopt_protocol = { .handler = ipv6_destopt_rcv, .flags = INET6_PROTO_NOPOLICY, }; static const struct inet6_protocol nodata_protocol = { .handler = dst_discard, .flags = INET6_PROTO_NOPOLICY, }; int __init ipv6_exthdrs_init(void) { int ret; ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING); if (ret) goto out; ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS); if (ret) goto out_rthdr; ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE); if (ret) goto out_destopt; out: return ret; out_destopt: inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS); out_rthdr: inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING); goto out; }; void ipv6_exthdrs_exit(void) { inet6_del_protocol(&nodata_protocol, IPPROTO_NONE); inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS); inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING); } /********************************** Hop-by-hop options. **********************************/ /* * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input(). */ static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb) { return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev); } static inline struct net *ipv6_skb_net(struct sk_buff *skb) { return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev); } /* Router Alert as of RFC 2711 */ static bool ipv6_hop_ra(struct sk_buff *skb, int optoff) { const unsigned char *nh = skb_network_header(skb); if (nh[optoff + 1] == 2) { IP6CB(skb)->flags |= IP6SKB_ROUTERALERT; memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra)); return true; } net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n", nh[optoff + 1]); kfree_skb(skb); return false; } /* Jumbo payload */ static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff) { const unsigned char *nh = skb_network_header(skb); struct net *net = ipv6_skb_net(skb); u32 pkt_len; if (nh[optoff + 1] != 4 || (optoff & 3) != 2) { net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n", nh[optoff+1]); IP6_INC_STATS_BH(net, ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS); goto drop; } pkt_len = ntohl(net_hdr_word(nh + optoff + 2)); if (pkt_len <= IPV6_MAXPLEN) { IP6_INC_STATS_BH(net, ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2); return false; } if (ipv6_hdr(skb)->payload_len) { IP6_INC_STATS_BH(net, ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff); return false; } if (pkt_len > skb->len - sizeof(struct ipv6hdr)) { IP6_INC_STATS_BH(net, ipv6_skb_idev(skb), IPSTATS_MIB_INTRUNCATEDPKTS); goto drop; } if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) goto drop; return true; drop: kfree_skb(skb); return false; } static const struct tlvtype_proc tlvprochopopt_lst[] = { { .type = IPV6_TLV_ROUTERALERT, .func = ipv6_hop_ra, }, { .type = IPV6_TLV_JUMBO, .func = ipv6_hop_jumbo, }, { -1, } }; int ipv6_parse_hopopts(struct sk_buff *skb) { struct inet6_skb_parm *opt = IP6CB(skb); /* * skb_network_header(skb) is equal to skb->data, and * skb_network_header_len(skb) is always equal to * sizeof(struct ipv6hdr) by definition of * hop-by-hop options. */ if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) || !pskb_may_pull(skb, (sizeof(struct ipv6hdr) + ((skb_transport_header(skb)[1] + 1) << 3)))) { kfree_skb(skb); return -1; } opt->flags |= IP6SKB_HOPBYHOP; if (ip6_parse_tlv(tlvprochopopt_lst, skb)) { skb->transport_header += (skb_transport_header(skb)[1] + 1) << 3; opt = IP6CB(skb); opt->nhoff = sizeof(struct ipv6hdr); return 1; } return -1; } /* * Creating outbound headers. * * "build" functions work when skb is filled from head to tail (datagram) * "push" functions work when headers are added from tail to head (tcp) * * In both cases we assume, that caller reserved enough room * for headers. */ static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto, struct ipv6_rt_hdr *opt, struct in6_addr **addr_p) { struct rt0_hdr *phdr, *ihdr; int hops; ihdr = (struct rt0_hdr *) opt; phdr = (struct rt0_hdr *) skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3); memcpy(phdr, ihdr, sizeof(struct rt0_hdr)); hops = ihdr->rt_hdr.hdrlen >> 1; if (hops > 1) memcpy(phdr->addr, ihdr->addr + 1, (hops - 1) * sizeof(struct in6_addr)); phdr->addr[hops - 1] = **addr_p; *addr_p = ihdr->addr; phdr->rt_hdr.nexthdr = *proto; *proto = NEXTHDR_ROUTING; } static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt) { struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt)); memcpy(h, opt, ipv6_optlen(opt)); h->nexthdr = *proto; *proto = type; } void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto, struct in6_addr **daddr) { if (opt->srcrt) { ipv6_push_rthdr(skb, proto, opt->srcrt, daddr); /* * IPV6_RTHDRDSTOPTS is ignored * unless IPV6_RTHDR is set (RFC3542). */ if (opt->dst0opt) ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt); } if (opt->hopopt) ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt); } EXPORT_SYMBOL(ipv6_push_nfrag_opts); void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto) { if (opt->dst1opt) ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt); } struct ipv6_txoptions * ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt) { struct ipv6_txoptions *opt2; opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC); if (opt2) { long dif = (char *)opt2 - (char *)opt; memcpy(opt2, opt, opt->tot_len); if (opt2->hopopt) *((char **)&opt2->hopopt) += dif; if (opt2->dst0opt) *((char **)&opt2->dst0opt) += dif; if (opt2->dst1opt) *((char **)&opt2->dst1opt) += dif; if (opt2->srcrt) *((char **)&opt2->srcrt) += dif; atomic_set(&opt2->refcnt, 1); } return opt2; } EXPORT_SYMBOL_GPL(ipv6_dup_options); static int ipv6_renew_option(void *ohdr, struct ipv6_opt_hdr __user *newopt, int newoptlen, int inherit, struct ipv6_opt_hdr **hdr, char **p) { if (inherit) { if (ohdr) { memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr)); *hdr = (struct ipv6_opt_hdr *)*p; *p += CMSG_ALIGN(ipv6_optlen(*hdr)); } } else { if (newopt) { if (copy_from_user(*p, newopt, newoptlen)) return -EFAULT; *hdr = (struct ipv6_opt_hdr *)*p; if (ipv6_optlen(*hdr) > newoptlen) return -EINVAL; *p += CMSG_ALIGN(newoptlen); } } return 0; } struct ipv6_txoptions * ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt, int newtype, struct ipv6_opt_hdr __user *newopt, int newoptlen) { int tot_len = 0; char *p; struct ipv6_txoptions *opt2; int err; if (opt) { if (newtype != IPV6_HOPOPTS && opt->hopopt) tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt)); if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt) tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt)); if (newtype != IPV6_RTHDR && opt->srcrt) tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt)); if (newtype != IPV6_DSTOPTS && opt->dst1opt) tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt)); } if (newopt && newoptlen) tot_len += CMSG_ALIGN(newoptlen); if (!tot_len) return NULL; tot_len += sizeof(*opt2); opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC); if (!opt2) return ERR_PTR(-ENOBUFS); memset(opt2, 0, tot_len); atomic_set(&opt2->refcnt, 1); opt2->tot_len = tot_len; p = (char *)(opt2 + 1); err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen, newtype != IPV6_HOPOPTS, &opt2->hopopt, &p); if (err) goto out; err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen, newtype != IPV6_RTHDRDSTOPTS, &opt2->dst0opt, &p); if (err) goto out; err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen, newtype != IPV6_RTHDR, (struct ipv6_opt_hdr **)&opt2->srcrt, &p); if (err) goto out; err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen, newtype != IPV6_DSTOPTS, &opt2->dst1opt, &p); if (err) goto out; opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) + (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) + (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0); opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0); return opt2; out: sock_kfree_s(sk, opt2, opt2->tot_len); return ERR_PTR(err); } struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space, struct ipv6_txoptions *opt) { /* * ignore the dest before srcrt unless srcrt is being included. * --yoshfuji */ if (opt && opt->dst0opt && !opt->srcrt) { if (opt_space != opt) { memcpy(opt_space, opt, sizeof(*opt_space)); opt = opt_space; } opt->opt_nflen -= ipv6_optlen(opt->dst0opt); opt->dst0opt = NULL; } return opt; } EXPORT_SYMBOL_GPL(ipv6_fixup_options); /** * fl6_update_dst - update flowi destination address with info given * by srcrt option, if any. * * @fl6: flowi6 for which daddr is to be updated * @opt: struct ipv6_txoptions in which to look for srcrt opt * @orig: copy of original daddr address if modified * * Returns NULL if no txoptions or no srcrt, otherwise returns orig * and initial value of fl6->daddr set in orig */ struct in6_addr *fl6_update_dst(struct flowi6 *fl6, const struct ipv6_txoptions *opt, struct in6_addr *orig) { if (!opt || !opt->srcrt) return NULL; *orig = fl6->daddr; fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr; return orig; } EXPORT_SYMBOL_GPL(fl6_update_dst);