| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * IPv6 input |
| * Linux INET6 implementation |
| * |
| * Authors: |
| * Pedro Roque <roque@di.fc.ul.pt> |
| * Ian P. Morris <I.P.Morris@soton.ac.uk> |
| * |
| * Based in linux/net/ipv4/ip_input.c |
| */ |
| /* Changes |
| * |
| * Mitsuru KANDA @USAGI and |
| * YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs(). |
| */ |
| |
| #include <linux/errno.h> |
| #include <linux/types.h> |
| #include <linux/socket.h> |
| #include <linux/sockios.h> |
| #include <linux/net.h> |
| #include <linux/netdevice.h> |
| #include <linux/in6.h> |
| #include <linux/icmpv6.h> |
| #include <linux/mroute6.h> |
| #include <linux/slab.h> |
| #include <linux/indirect_call_wrapper.h> |
| |
| #include <linux/netfilter.h> |
| #include <linux/netfilter_ipv6.h> |
| |
| #include <net/sock.h> |
| #include <net/snmp.h> |
| #include <net/udp.h> |
| |
| #include <net/ipv6.h> |
| #include <net/protocol.h> |
| #include <net/transp_v6.h> |
| #include <net/rawv6.h> |
| #include <net/ndisc.h> |
| #include <net/ip6_route.h> |
| #include <net/addrconf.h> |
| #include <net/xfrm.h> |
| #include <net/inet_ecn.h> |
| #include <net/dst_metadata.h> |
| |
| static void ip6_rcv_finish_core(struct net *net, struct sock *sk, |
| struct sk_buff *skb) |
| { |
| if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) && |
| !skb_dst(skb) && !skb->sk) { |
| switch (ipv6_hdr(skb)->nexthdr) { |
| case IPPROTO_TCP: |
| if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) |
| tcp_v6_early_demux(skb); |
| break; |
| case IPPROTO_UDP: |
| if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) |
| udp_v6_early_demux(skb); |
| break; |
| } |
| } |
| |
| if (!skb_valid_dst(skb)) |
| ip6_route_input(skb); |
| } |
| |
| int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| /* if ingress device is enslaved to an L3 master device pass the |
| * skb to its handler for processing |
| */ |
| skb = l3mdev_ip6_rcv(skb); |
| if (!skb) |
| return NET_RX_SUCCESS; |
| ip6_rcv_finish_core(net, sk, skb); |
| |
| return dst_input(skb); |
| } |
| |
| static void ip6_sublist_rcv_finish(struct list_head *head) |
| { |
| struct sk_buff *skb, *next; |
| |
| list_for_each_entry_safe(skb, next, head, list) { |
| skb_list_del_init(skb); |
| dst_input(skb); |
| } |
| } |
| |
| static bool ip6_can_use_hint(const struct sk_buff *skb, |
| const struct sk_buff *hint) |
| { |
| return hint && !skb_dst(skb) && |
| ipv6_addr_equal(&ipv6_hdr(hint)->daddr, &ipv6_hdr(skb)->daddr); |
| } |
| |
| static struct sk_buff *ip6_extract_route_hint(const struct net *net, |
| struct sk_buff *skb) |
| { |
| if (fib6_routes_require_src(net) || fib6_has_custom_rules(net)) |
| return NULL; |
| |
| return skb; |
| } |
| |
| static void ip6_list_rcv_finish(struct net *net, struct sock *sk, |
| struct list_head *head) |
| { |
| struct sk_buff *skb, *next, *hint = NULL; |
| struct dst_entry *curr_dst = NULL; |
| struct list_head sublist; |
| |
| INIT_LIST_HEAD(&sublist); |
| list_for_each_entry_safe(skb, next, head, list) { |
| struct dst_entry *dst; |
| |
| skb_list_del_init(skb); |
| /* if ingress device is enslaved to an L3 master device pass the |
| * skb to its handler for processing |
| */ |
| skb = l3mdev_ip6_rcv(skb); |
| if (!skb) |
| continue; |
| |
| if (ip6_can_use_hint(skb, hint)) |
| skb_dst_copy(skb, hint); |
| else |
| ip6_rcv_finish_core(net, sk, skb); |
| dst = skb_dst(skb); |
| if (curr_dst != dst) { |
| hint = ip6_extract_route_hint(net, skb); |
| |
| /* dispatch old sublist */ |
| if (!list_empty(&sublist)) |
| ip6_sublist_rcv_finish(&sublist); |
| /* start new sublist */ |
| INIT_LIST_HEAD(&sublist); |
| curr_dst = dst; |
| } |
| list_add_tail(&skb->list, &sublist); |
| } |
| /* dispatch final sublist */ |
| ip6_sublist_rcv_finish(&sublist); |
| } |
| |
| static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev, |
| struct net *net) |
| { |
| const struct ipv6hdr *hdr; |
| u32 pkt_len; |
| struct inet6_dev *idev; |
| |
| if (skb->pkt_type == PACKET_OTHERHOST) { |
| kfree_skb(skb); |
| return NULL; |
| } |
| |
| rcu_read_lock(); |
| |
| idev = __in6_dev_get(skb->dev); |
| |
| __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len); |
| |
| if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL || |
| !idev || unlikely(idev->cnf.disable_ipv6)) { |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); |
| goto drop; |
| } |
| |
| memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm)); |
| |
| /* |
| * Store incoming device index. When the packet will |
| * be queued, we cannot refer to skb->dev anymore. |
| * |
| * BTW, when we send a packet for our own local address on a |
| * non-loopback interface (e.g. ethX), it is being delivered |
| * via the loopback interface (lo) here; skb->dev = loopback_dev. |
| * It, however, should be considered as if it is being |
| * arrived via the sending interface (ethX), because of the |
| * nature of scoping architecture. --yoshfuji |
| */ |
| IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex; |
| |
| if (unlikely(!pskb_may_pull(skb, sizeof(*hdr)))) |
| goto err; |
| |
| hdr = ipv6_hdr(skb); |
| |
| if (hdr->version != 6) |
| goto err; |
| |
| __IP6_ADD_STATS(net, idev, |
| IPSTATS_MIB_NOECTPKTS + |
| (ipv6_get_dsfield(hdr) & INET_ECN_MASK), |
| max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs)); |
| /* |
| * RFC4291 2.5.3 |
| * The loopback address must not be used as the source address in IPv6 |
| * packets that are sent outside of a single node. [..] |
| * A packet received on an interface with a destination address |
| * of loopback must be dropped. |
| */ |
| if ((ipv6_addr_loopback(&hdr->saddr) || |
| ipv6_addr_loopback(&hdr->daddr)) && |
| !(dev->flags & IFF_LOOPBACK) && |
| !netif_is_l3_master(dev)) |
| goto err; |
| |
| /* RFC4291 Errata ID: 3480 |
| * Interface-Local scope spans only a single interface on a |
| * node and is useful only for loopback transmission of |
| * multicast. Packets with interface-local scope received |
| * from another node must be discarded. |
| */ |
| if (!(skb->pkt_type == PACKET_LOOPBACK || |
| dev->flags & IFF_LOOPBACK) && |
| ipv6_addr_is_multicast(&hdr->daddr) && |
| IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) |
| goto err; |
| |
| /* If enabled, drop unicast packets that were encapsulated in link-layer |
| * multicast or broadcast to protected against the so-called "hole-196" |
| * attack in 802.11 wireless. |
| */ |
| if (!ipv6_addr_is_multicast(&hdr->daddr) && |
| (skb->pkt_type == PACKET_BROADCAST || |
| skb->pkt_type == PACKET_MULTICAST) && |
| idev->cnf.drop_unicast_in_l2_multicast) |
| goto err; |
| |
| /* RFC4291 2.7 |
| * Nodes must not originate a packet to a multicast address whose scope |
| * field contains the reserved value 0; if such a packet is received, it |
| * must be silently dropped. |
| */ |
| if (ipv6_addr_is_multicast(&hdr->daddr) && |
| IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0) |
| goto err; |
| |
| /* |
| * RFC4291 2.7 |
| * Multicast addresses must not be used as source addresses in IPv6 |
| * packets or appear in any Routing header. |
| */ |
| if (ipv6_addr_is_multicast(&hdr->saddr)) |
| goto err; |
| |
| skb->transport_header = skb->network_header + sizeof(*hdr); |
| IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); |
| |
| pkt_len = ntohs(hdr->payload_len); |
| |
| /* pkt_len may be zero if Jumbo payload option is present */ |
| if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { |
| if (pkt_len + sizeof(struct ipv6hdr) > skb->len) { |
| __IP6_INC_STATS(net, |
| idev, IPSTATS_MIB_INTRUNCATEDPKTS); |
| goto drop; |
| } |
| if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) { |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); |
| goto drop; |
| } |
| hdr = ipv6_hdr(skb); |
| } |
| |
| if (hdr->nexthdr == NEXTHDR_HOP) { |
| if (ipv6_parse_hopopts(skb) < 0) { |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); |
| rcu_read_unlock(); |
| return NULL; |
| } |
| } |
| |
| rcu_read_unlock(); |
| |
| /* Must drop socket now because of tproxy. */ |
| if (!skb_sk_is_prefetched(skb)) |
| skb_orphan(skb); |
| |
| return skb; |
| err: |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS); |
| drop: |
| rcu_read_unlock(); |
| kfree_skb(skb); |
| return NULL; |
| } |
| |
| int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) |
| { |
| struct net *net = dev_net(skb->dev); |
| |
| skb = ip6_rcv_core(skb, dev, net); |
| if (skb == NULL) |
| return NET_RX_DROP; |
| return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, |
| net, NULL, skb, dev, NULL, |
| ip6_rcv_finish); |
| } |
| |
| static void ip6_sublist_rcv(struct list_head *head, struct net_device *dev, |
| struct net *net) |
| { |
| NF_HOOK_LIST(NFPROTO_IPV6, NF_INET_PRE_ROUTING, net, NULL, |
| head, dev, NULL, ip6_rcv_finish); |
| ip6_list_rcv_finish(net, NULL, head); |
| } |
| |
| /* Receive a list of IPv6 packets */ |
| void ipv6_list_rcv(struct list_head *head, struct packet_type *pt, |
| struct net_device *orig_dev) |
| { |
| struct net_device *curr_dev = NULL; |
| struct net *curr_net = NULL; |
| struct sk_buff *skb, *next; |
| struct list_head sublist; |
| |
| INIT_LIST_HEAD(&sublist); |
| list_for_each_entry_safe(skb, next, head, list) { |
| struct net_device *dev = skb->dev; |
| struct net *net = dev_net(dev); |
| |
| skb_list_del_init(skb); |
| skb = ip6_rcv_core(skb, dev, net); |
| if (skb == NULL) |
| continue; |
| |
| if (curr_dev != dev || curr_net != net) { |
| /* dispatch old sublist */ |
| if (!list_empty(&sublist)) |
| ip6_sublist_rcv(&sublist, curr_dev, curr_net); |
| /* start new sublist */ |
| INIT_LIST_HEAD(&sublist); |
| curr_dev = dev; |
| curr_net = net; |
| } |
| list_add_tail(&skb->list, &sublist); |
| } |
| /* dispatch final sublist */ |
| if (!list_empty(&sublist)) |
| ip6_sublist_rcv(&sublist, curr_dev, curr_net); |
| } |
| |
| INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *)); |
| |
| /* |
| * Deliver the packet to the host |
| */ |
| void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr, |
| bool have_final) |
| { |
| const struct inet6_protocol *ipprot; |
| struct inet6_dev *idev; |
| unsigned int nhoff; |
| bool raw; |
| |
| /* |
| * Parse extension headers |
| */ |
| |
| resubmit: |
| idev = ip6_dst_idev(skb_dst(skb)); |
| nhoff = IP6CB(skb)->nhoff; |
| if (!have_final) { |
| if (!pskb_pull(skb, skb_transport_offset(skb))) |
| goto discard; |
| nexthdr = skb_network_header(skb)[nhoff]; |
| } |
| |
| resubmit_final: |
| raw = raw6_local_deliver(skb, nexthdr); |
| ipprot = rcu_dereference(inet6_protos[nexthdr]); |
| if (ipprot) { |
| int ret; |
| |
| if (have_final) { |
| if (!(ipprot->flags & INET6_PROTO_FINAL)) { |
| /* Once we've seen a final protocol don't |
| * allow encapsulation on any non-final |
| * ones. This allows foo in UDP encapsulation |
| * to work. |
| */ |
| goto discard; |
| } |
| } else if (ipprot->flags & INET6_PROTO_FINAL) { |
| const struct ipv6hdr *hdr; |
| int sdif = inet6_sdif(skb); |
| struct net_device *dev; |
| |
| /* Only do this once for first final protocol */ |
| have_final = true; |
| |
| /* Free reference early: we don't need it any more, |
| and it may hold ip_conntrack module loaded |
| indefinitely. */ |
| nf_reset_ct(skb); |
| |
| skb_postpull_rcsum(skb, skb_network_header(skb), |
| skb_network_header_len(skb)); |
| hdr = ipv6_hdr(skb); |
| |
| /* skb->dev passed may be master dev for vrfs. */ |
| if (sdif) { |
| dev = dev_get_by_index_rcu(net, sdif); |
| if (!dev) |
| goto discard; |
| } else { |
| dev = skb->dev; |
| } |
| |
| if (ipv6_addr_is_multicast(&hdr->daddr) && |
| !ipv6_chk_mcast_addr(dev, &hdr->daddr, |
| &hdr->saddr) && |
| !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) |
| goto discard; |
| } |
| if (!(ipprot->flags & INET6_PROTO_NOPOLICY) && |
| !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) |
| goto discard; |
| |
| ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv, |
| skb); |
| if (ret > 0) { |
| if (ipprot->flags & INET6_PROTO_FINAL) { |
| /* Not an extension header, most likely UDP |
| * encapsulation. Use return value as nexthdr |
| * protocol not nhoff (which presumably is |
| * not set by handler). |
| */ |
| nexthdr = ret; |
| goto resubmit_final; |
| } else { |
| goto resubmit; |
| } |
| } else if (ret == 0) { |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); |
| } |
| } else { |
| if (!raw) { |
| if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { |
| __IP6_INC_STATS(net, idev, |
| IPSTATS_MIB_INUNKNOWNPROTOS); |
| icmpv6_send(skb, ICMPV6_PARAMPROB, |
| ICMPV6_UNK_NEXTHDR, nhoff); |
| } |
| kfree_skb(skb); |
| } else { |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS); |
| consume_skb(skb); |
| } |
| } |
| return; |
| |
| discard: |
| __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS); |
| kfree_skb(skb); |
| } |
| |
| static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| rcu_read_lock(); |
| ip6_protocol_deliver_rcu(net, skb, 0, false); |
| rcu_read_unlock(); |
| |
| return 0; |
| } |
| |
| |
| int ip6_input(struct sk_buff *skb) |
| { |
| return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, |
| dev_net(skb->dev), NULL, skb, skb->dev, NULL, |
| ip6_input_finish); |
| } |
| EXPORT_SYMBOL_GPL(ip6_input); |
| |
| int ip6_mc_input(struct sk_buff *skb) |
| { |
| int sdif = inet6_sdif(skb); |
| const struct ipv6hdr *hdr; |
| struct net_device *dev; |
| bool deliver; |
| |
| __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev), |
| __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST, |
| skb->len); |
| |
| /* skb->dev passed may be master dev for vrfs. */ |
| if (sdif) { |
| rcu_read_lock(); |
| dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif); |
| if (!dev) { |
| rcu_read_unlock(); |
| kfree_skb(skb); |
| return -ENODEV; |
| } |
| } else { |
| dev = skb->dev; |
| } |
| |
| hdr = ipv6_hdr(skb); |
| deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL); |
| if (sdif) |
| rcu_read_unlock(); |
| |
| #ifdef CONFIG_IPV6_MROUTE |
| /* |
| * IPv6 multicast router mode is now supported ;) |
| */ |
| if (atomic_read(&dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding) && |
| !(ipv6_addr_type(&hdr->daddr) & |
| (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) && |
| likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) { |
| /* |
| * Okay, we try to forward - split and duplicate |
| * packets. |
| */ |
| struct sk_buff *skb2; |
| struct inet6_skb_parm *opt = IP6CB(skb); |
| |
| /* Check for MLD */ |
| if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) { |
| /* Check if this is a mld message */ |
| u8 nexthdr = hdr->nexthdr; |
| __be16 frag_off; |
| int offset; |
| |
| /* Check if the value of Router Alert |
| * is for MLD (0x0000). |
| */ |
| if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) { |
| deliver = false; |
| |
| if (!ipv6_ext_hdr(nexthdr)) { |
| /* BUG */ |
| goto out; |
| } |
| offset = ipv6_skip_exthdr(skb, sizeof(*hdr), |
| &nexthdr, &frag_off); |
| if (offset < 0) |
| goto out; |
| |
| if (ipv6_is_mld(skb, nexthdr, offset)) |
| deliver = true; |
| |
| goto out; |
| } |
| /* unknown RA - process it normally */ |
| } |
| |
| if (deliver) |
| skb2 = skb_clone(skb, GFP_ATOMIC); |
| else { |
| skb2 = skb; |
| skb = NULL; |
| } |
| |
| if (skb2) { |
| ip6_mr_input(skb2); |
| } |
| } |
| out: |
| #endif |
| if (likely(deliver)) |
| ip6_input(skb); |
| else { |
| /* discard */ |
| kfree_skb(skb); |
| } |
| |
| return 0; |
| } |