// SPDX-License-Identifier: GPL-2.0-or-later /* * Extension Header handling for IPv6 * Linux INET6 implementation * * Authors: * Pedro Roque * Andi Kleen * Alexey Kuznetsov */ /* 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 #include #if IS_ENABLED(CONFIG_IPV6_MIP6) #include #endif #include #include #ifdef CONFIG_IPV6_SEG6_HMAC #include #endif #include #include #include #include #include /********************* Generic functions *********************/ /* An unknown option is detected, decide what to do */ static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff, bool disallow_unknowns) { if (disallow_unknowns) { /* If unknown TLVs are disallowed by configuration * then always silently drop packet. Note this also * means no ICMP parameter problem is sent which * could be a good property to mitigate a reflection DOS * attack. */ goto drop; } 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; fallthrough; case 2: /* send ICMP PARM PROB regardless and drop packet */ icmpv6_param_prob_reason(skb, ICMPV6_UNK_OPTION, optoff, SKB_DROP_REASON_UNHANDLED_PROTO); return false; } drop: kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO); return false; } static bool ipv6_hop_ra(struct sk_buff *skb, int optoff); static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff); static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff); static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff); #if IS_ENABLED(CONFIG_IPV6_MIP6) static bool ipv6_dest_hao(struct sk_buff *skb, int optoff); #endif /* Parse tlv encoded option header (hop-by-hop or destination) */ static bool ip6_parse_tlv(bool hopbyhop, struct sk_buff *skb, int max_count) { int len = (skb_transport_header(skb)[1] + 1) << 3; const unsigned char *nh = skb_network_header(skb); int off = skb_network_header_len(skb); bool disallow_unknowns = false; int tlv_count = 0; int padlen = 0; if (unlikely(max_count < 0)) { disallow_unknowns = true; max_count = -max_count; } off += 2; len -= 2; while (len > 0) { int optlen, i; if (nh[off] == IPV6_TLV_PAD1) { padlen++; if (padlen > 7) goto bad; off++; len--; continue; } if (len < 2) goto bad; optlen = nh[off + 1] + 2; if (optlen > len) goto bad; if (nh[off] == 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; } } else { tlv_count++; if (tlv_count > max_count) goto bad; if (hopbyhop) { switch (nh[off]) { case IPV6_TLV_ROUTERALERT: if (!ipv6_hop_ra(skb, off)) return false; break; case IPV6_TLV_IOAM: if (!ipv6_hop_ioam(skb, off)) return false; break; case IPV6_TLV_JUMBO: if (!ipv6_hop_jumbo(skb, off)) return false; break; case IPV6_TLV_CALIPSO: if (!ipv6_hop_calipso(skb, off)) return false; break; default: if (!ip6_tlvopt_unknown(skb, off, disallow_unknowns)) return false; break; } } else { switch (nh[off]) { #if IS_ENABLED(CONFIG_IPV6_MIP6) case IPV6_TLV_HAO: if (!ipv6_dest_hao(skb, off)) return false; break; #endif default: if (!ip6_tlvopt_unknown(skb, off, disallow_unknowns)) return false; break; } } padlen = 0; } off += optlen; len -= optlen; } if (len == 0) return true; bad: kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR); 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); SKB_DR(reason); 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); SKB_DR_SET(reason, IP_INHDR); goto discard; } if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) { net_dbg_ratelimited("hao is not an unicast addr: %pI6\n", &hao->addr); SKB_DR_SET(reason, INVALID_PROTO); goto discard; } ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr, (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS); if (unlikely(ret < 0)) { SKB_DR_SET(reason, XFRM_POLICY); 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; swap(ipv6h->saddr, hao->addr); if (skb->tstamp == 0) __net_timestamp(skb); return true; discard: kfree_skb_reason(skb, reason); return false; } #endif static int ipv6_destopt_rcv(struct sk_buff *skb) { struct inet6_dev *idev = __in6_dev_get(skb->dev); struct inet6_skb_parm *opt = IP6CB(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) __u16 dstbuf; #endif struct dst_entry *dst = skb_dst(skb); struct net *net = dev_net(skb->dev); int extlen; 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(dev_net(dst->dev), idev, IPSTATS_MIB_INHDRERRORS); fail_and_free: kfree_skb(skb); return -1; } extlen = (skb_transport_header(skb)[1] + 1) << 3; if (extlen > net->ipv6.sysctl.max_dst_opts_len) goto fail_and_free; opt->lastopt = opt->dst1 = skb_network_header_len(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) dstbuf = opt->dst1; #endif if (ip6_parse_tlv(false, skb, net->ipv6.sysctl.max_dst_opts_cnt)) { skb->transport_header += extlen; opt = IP6CB(skb); #if IS_ENABLED(CONFIG_IPV6_MIP6) opt->nhoff = dstbuf; #else opt->nhoff = opt->dst1; #endif return 1; } __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); return -1; } static void seg6_update_csum(struct sk_buff *skb) { struct ipv6_sr_hdr *hdr; struct in6_addr *addr; __be32 from, to; /* srh is at transport offset and seg_left is already decremented * but daddr is not yet updated with next segment */ hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb); addr = hdr->segments + hdr->segments_left; hdr->segments_left++; from = *(__be32 *)hdr; hdr->segments_left--; to = *(__be32 *)hdr; /* update skb csum with diff resulting from seg_left decrement */ update_csum_diff4(skb, from, to); /* compute csum diff between current and next segment and update */ update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr), (__be32 *)addr); } static int ipv6_srh_rcv(struct sk_buff *skb) { struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(skb->dev); struct ipv6_sr_hdr *hdr; struct inet6_dev *idev; struct in6_addr *addr; int accept_seg6; hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb); idev = __in6_dev_get(skb->dev); accept_seg6 = net->ipv6.devconf_all->seg6_enabled; if (accept_seg6 > idev->cnf.seg6_enabled) accept_seg6 = idev->cnf.seg6_enabled; if (!accept_seg6) { kfree_skb(skb); return -1; } #ifdef CONFIG_IPV6_SEG6_HMAC if (!seg6_hmac_validate_skb(skb)) { kfree_skb(skb); return -1; } #endif looped_back: if (hdr->segments_left == 0) { if (hdr->nexthdr == NEXTHDR_IPV6 || hdr->nexthdr == NEXTHDR_IPV4) { int offset = (hdr->hdrlen + 1) << 3; skb_postpull_rcsum(skb, skb_network_header(skb), skb_network_header_len(skb)); skb_pull(skb, offset); skb_postpull_rcsum(skb, skb_transport_header(skb), offset); skb_reset_network_header(skb); skb_reset_transport_header(skb); skb->encapsulation = 0; if (hdr->nexthdr == NEXTHDR_IPV4) skb->protocol = htons(ETH_P_IP); __skb_tunnel_rx(skb, skb->dev, net); netif_rx(skb); return -1; } opt->srcrt = skb_network_header_len(skb); opt->lastopt = opt->srcrt; skb->transport_header += (hdr->hdrlen + 1) << 3; opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb); return 1; } if (hdr->segments_left >= (hdr->hdrlen >> 1)) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, ((&hdr->segments_left) - skb_network_header(skb))); return -1; } if (skb_cloned(skb)) { if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) { __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_OUTDISCARDS); kfree_skb(skb); return -1; } hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb); } hdr->segments_left--; addr = hdr->segments + hdr->segments_left; skb_push(skb, sizeof(struct ipv6hdr)); if (skb->ip_summed == CHECKSUM_COMPLETE) seg6_update_csum(skb); ipv6_hdr(skb)->daddr = *addr; ip6_route_input(skb); if (skb_dst(skb)->error) { dst_input(skb); return -1; } if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) { if (ipv6_hdr(skb)->hop_limit <= 1) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0); kfree_skb(skb); return -1; } ipv6_hdr(skb)->hop_limit--; skb_pull(skb, sizeof(struct ipv6hdr)); goto looped_back; } dst_input(skb); return -1; } static int ipv6_rpl_srh_rcv(struct sk_buff *skb) { struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr; struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(skb->dev); struct inet6_dev *idev; struct ipv6hdr *oldhdr; unsigned char *buf; int accept_rpl_seg; int i, err; u64 n = 0; u32 r; idev = __in6_dev_get(skb->dev); accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled; if (accept_rpl_seg > idev->cnf.rpl_seg_enabled) accept_rpl_seg = idev->cnf.rpl_seg_enabled; if (!accept_rpl_seg) { kfree_skb(skb); return -1; } looped_back: hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb); if (hdr->segments_left == 0) { if (hdr->nexthdr == NEXTHDR_IPV6) { int offset = (hdr->hdrlen + 1) << 3; skb_postpull_rcsum(skb, skb_network_header(skb), skb_network_header_len(skb)); skb_pull(skb, offset); skb_postpull_rcsum(skb, skb_transport_header(skb), offset); skb_reset_network_header(skb); skb_reset_transport_header(skb); skb->encapsulation = 0; __skb_tunnel_rx(skb, skb->dev, net); netif_rx(skb); return -1; } opt->srcrt = skb_network_header_len(skb); opt->lastopt = opt->srcrt; skb->transport_header += (hdr->hdrlen + 1) << 3; opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb); return 1; } n = (hdr->hdrlen << 3) - hdr->pad - (16 - hdr->cmpre); r = do_div(n, (16 - hdr->cmpri)); /* checks if calculation was without remainder and n fits into * unsigned char which is segments_left field. Should not be * higher than that. */ if (r || (n + 1) > 255) { kfree_skb(skb); return -1; } if (hdr->segments_left > n + 1) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, ((&hdr->segments_left) - skb_network_header(skb))); return -1; } hdr->segments_left--; i = n - hdr->segments_left; buf = kcalloc(struct_size(hdr, segments.addr, n + 2), 2, GFP_ATOMIC); if (unlikely(!buf)) { kfree_skb(skb); return -1; } ohdr = (struct ipv6_rpl_sr_hdr *)buf; ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n); chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3)); if (ipv6_addr_is_multicast(&ohdr->rpl_segaddr[i])) { kfree_skb(skb); kfree(buf); return -1; } err = ipv6_chk_rpl_srh_loop(net, ohdr->rpl_segaddr, n + 1); if (err) { icmpv6_send(skb, ICMPV6_PARAMPROB, 0, 0); kfree_skb(skb); kfree(buf); return -1; } swap(ipv6_hdr(skb)->daddr, ohdr->rpl_segaddr[i]); ipv6_rpl_srh_compress(chdr, ohdr, &ipv6_hdr(skb)->daddr, n); oldhdr = ipv6_hdr(skb); skb_pull(skb, ((hdr->hdrlen + 1) << 3)); skb_postpull_rcsum(skb, oldhdr, sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3)); if (unlikely(!hdr->segments_left)) { if (pskb_expand_head(skb, sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3), 0, GFP_ATOMIC)) { __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_OUTDISCARDS); kfree_skb(skb); kfree(buf); return -1; } oldhdr = ipv6_hdr(skb); } skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr)); skb_reset_network_header(skb); skb_mac_header_rebuild(skb); skb_set_transport_header(skb, sizeof(struct ipv6hdr)); memmove(ipv6_hdr(skb), oldhdr, sizeof(struct ipv6hdr)); memcpy(skb_transport_header(skb), chdr, (chdr->hdrlen + 1) << 3); ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr)); skb_postpush_rcsum(skb, ipv6_hdr(skb), sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3)); kfree(buf); ip6_route_input(skb); if (skb_dst(skb)->error) { dst_input(skb); return -1; } if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) { if (ipv6_hdr(skb)->hop_limit <= 1) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0); kfree_skb(skb); return -1; } ipv6_hdr(skb)->hop_limit--; skb_pull(skb, sizeof(struct ipv6hdr)); goto looped_back; } dst_input(skb); return -1; } /******************************** Routing header. ********************************/ /* called with rcu_read_lock() */ static int ipv6_rthdr_rcv(struct sk_buff *skb) { struct inet6_dev *idev = __in6_dev_get(skb->dev); struct inet6_skb_parm *opt = IP6CB(skb); struct in6_addr *addr = NULL; 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; 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(net, idev, 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(net, idev, IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } switch (hdr->type) { case IPV6_SRCRT_TYPE_4: /* segment routing */ return ipv6_srh_rcv(skb); case IPV6_SRCRT_TYPE_3: /* rpl segment routing */ return ipv6_rpl_srh_rcv(skb); default: break; } 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(net, idev, 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(net, idev, 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(net, idev, 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(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(net, idev, IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } break; #endif default: break; } if (ipv6_addr_is_multicast(addr)) { __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS); kfree_skb(skb); return -1; } swap(*addr, ipv6_hdr(skb)->daddr); 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(net, idev, 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(net, idev, 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 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_reason(skb, SKB_DROP_REASON_IP_INHDR); return false; } /* IOAM */ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff) { struct ioam6_trace_hdr *trace; struct ioam6_namespace *ns; struct ioam6_hdr *hdr; /* Bad alignment (must be 4n-aligned) */ if (optoff & 3) goto drop; /* Ignore if IOAM is not enabled on ingress */ if (!__in6_dev_get(skb->dev)->cnf.ioam6_enabled) goto ignore; /* Truncated Option header */ hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff); if (hdr->opt_len < 2) goto drop; switch (hdr->type) { case IOAM6_TYPE_PREALLOC: /* Truncated Pre-allocated Trace header */ if (hdr->opt_len < 2 + sizeof(*trace)) goto drop; /* Malformed Pre-allocated Trace header */ trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr)); if (hdr->opt_len < 2 + sizeof(*trace) + trace->remlen * 4) goto drop; /* Ignore if the IOAM namespace is unknown */ ns = ioam6_namespace(ipv6_skb_net(skb), trace->namespace_id); if (!ns) goto ignore; if (!skb_valid_dst(skb)) ip6_route_input(skb); ioam6_fill_trace_data(skb, ns, trace, true); break; default: break; } ignore: return true; drop: kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR); return false; } /* Jumbo payload */ static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff) { const unsigned char *nh = skb_network_header(skb); SKB_DR(reason); 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]); SKB_DR_SET(reason, IP_INHDR); goto drop; } pkt_len = ntohl(*(__be32 *)(nh + optoff + 2)); if (pkt_len <= IPV6_MAXPLEN) { icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff + 2, SKB_DROP_REASON_IP_INHDR); return false; } if (ipv6_hdr(skb)->payload_len) { icmpv6_param_prob_reason(skb, ICMPV6_HDR_FIELD, optoff, SKB_DROP_REASON_IP_INHDR); return false; } if (pkt_len > skb->len - sizeof(struct ipv6hdr)) { SKB_DR_SET(reason, PKT_TOO_SMALL); goto drop; } if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) goto drop; IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM; return true; drop: kfree_skb_reason(skb, reason); return false; } /* CALIPSO RFC 5570 */ static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff) { const unsigned char *nh = skb_network_header(skb); if (nh[optoff + 1] < 8) goto drop; if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1]) goto drop; if (!calipso_validate(skb, nh + optoff)) goto drop; return true; drop: kfree_skb_reason(skb, SKB_DROP_REASON_IP_INHDR); return false; } int ipv6_parse_hopopts(struct sk_buff *skb) { struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(skb->dev); int extlen; /* * 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)))) { fail_and_free: kfree_skb(skb); return -1; } extlen = (skb_transport_header(skb)[1] + 1) << 3; if (extlen > net->ipv6.sysctl.max_hbh_opts_len) goto fail_and_free; opt->flags |= IP6SKB_HOPBYHOP; if (ip6_parse_tlv(true, skb, net->ipv6.sysctl.max_hbh_opts_cnt)) { skb->transport_header += extlen; 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_rthdr0(struct sk_buff *skb, u8 *proto, struct ipv6_rt_hdr *opt, struct in6_addr **addr_p, struct in6_addr *saddr) { struct rt0_hdr *phdr, *ihdr; int hops; ihdr = (struct rt0_hdr *) opt; phdr = 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_rthdr4(struct sk_buff *skb, u8 *proto, struct ipv6_rt_hdr *opt, struct in6_addr **addr_p, struct in6_addr *saddr) { struct ipv6_sr_hdr *sr_phdr, *sr_ihdr; int plen, hops; sr_ihdr = (struct ipv6_sr_hdr *)opt; plen = (sr_ihdr->hdrlen + 1) << 3; sr_phdr = skb_push(skb, plen); memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr)); hops = sr_ihdr->first_segment + 1; memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1, (hops - 1) * sizeof(struct in6_addr)); sr_phdr->segments[0] = **addr_p; *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left]; if (sr_ihdr->hdrlen > hops * 2) { int tlvs_offset, tlvs_length; tlvs_offset = (1 + hops * 2) << 3; tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3; memcpy((char *)sr_phdr + tlvs_offset, (char *)sr_ihdr + tlvs_offset, tlvs_length); } #ifdef CONFIG_IPV6_SEG6_HMAC if (sr_has_hmac(sr_phdr)) { struct net *net = NULL; if (skb->dev) net = dev_net(skb->dev); else if (skb->sk) net = sock_net(skb->sk); WARN_ON(!net); if (net) seg6_push_hmac(net, saddr, sr_phdr); } #endif sr_phdr->nexthdr = *proto; *proto = NEXTHDR_ROUTING; } static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto, struct ipv6_rt_hdr *opt, struct in6_addr **addr_p, struct in6_addr *saddr) { switch (opt->type) { case IPV6_SRCRT_TYPE_0: case IPV6_SRCRT_STRICT: case IPV6_SRCRT_TYPE_2: ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr); break; case IPV6_SRCRT_TYPE_4: ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr); break; default: break; } } static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt) { struct ipv6_opt_hdr *h = 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, struct in6_addr *saddr) { if (opt->srcrt) { ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr); /* * 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); } 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); } EXPORT_SYMBOL(ipv6_push_frag_opts); 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; refcount_set(&opt2->refcnt, 1); } return opt2; } EXPORT_SYMBOL_GPL(ipv6_dup_options); static void ipv6_renew_option(int renewtype, struct ipv6_opt_hdr **dest, struct ipv6_opt_hdr *old, struct ipv6_opt_hdr *new, int newtype, char **p) { struct ipv6_opt_hdr *src; src = (renewtype == newtype ? new : old); if (!src) return; memcpy(*p, src, ipv6_optlen(src)); *dest = (struct ipv6_opt_hdr *)*p; *p += CMSG_ALIGN(ipv6_optlen(*dest)); } /** * ipv6_renew_options - replace a specific ext hdr with a new one. * * @sk: sock from which to allocate memory * @opt: original options * @newtype: option type to replace in @opt * @newopt: new option of type @newtype to replace (user-mem) * * Returns a new set of options which is a copy of @opt with the * option type @newtype replaced with @newopt. * * @opt may be NULL, in which case a new set of options is returned * containing just @newopt. * * @newopt may be NULL, in which case the specified option type is * not copied into the new set of options. * * The new set of options is allocated from the socket option memory * buffer of @sk. */ struct ipv6_txoptions * ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt, int newtype, struct ipv6_opt_hdr *newopt) { int tot_len = 0; char *p; struct ipv6_txoptions *opt2; 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) tot_len += CMSG_ALIGN(ipv6_optlen(newopt)); 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); refcount_set(&opt2->refcnt, 1); opt2->tot_len = tot_len; p = (char *)(opt2 + 1); ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt, (opt ? opt->hopopt : NULL), newopt, newtype, &p); ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt, (opt ? opt->dst0opt : NULL), newopt, newtype, &p); ipv6_renew_option(IPV6_RTHDR, (struct ipv6_opt_hdr **)&opt2->srcrt, (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL), newopt, newtype, &p); ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt, (opt ? opt->dst1opt : NULL), newopt, newtype, &p); 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; } 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->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; switch (opt->srcrt->type) { case IPV6_SRCRT_TYPE_0: case IPV6_SRCRT_STRICT: case IPV6_SRCRT_TYPE_2: fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr; break; case IPV6_SRCRT_TYPE_4: { struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt; fl6->daddr = srh->segments[srh->segments_left]; break; } default: return NULL; } return orig; } EXPORT_SYMBOL_GPL(fl6_update_dst);