net/netfilter/nf_conntrack_proto_icmpv6.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C)2003,2004 USAGI/WIDE Project
   4  *
   5  * Author:
   6  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/timer.h>
  11 #include <linux/module.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/in6.h>
  14 #include <linux/icmpv6.h>
  15 #include <linux/ipv6.h>
  16 #include <net/ipv6.h>
  17 #include <net/ip6_checksum.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/netfilter_ipv6.h>
  20 #include <net/netfilter/nf_conntrack_tuple.h>
  21 #include <net/netfilter/nf_conntrack_l4proto.h>
  22 #include <net/netfilter/nf_conntrack_core.h>
  23 #include <net/netfilter/nf_conntrack_timeout.h>
  24 #include <net/netfilter/nf_conntrack_zones.h>
  25 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  26 #include <net/netfilter/nf_log.h>
  27
  28 static const unsigned int nf_ct_icmpv6_timeout = 30*HZ;
  29
  30 bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  31                          unsigned int dataoff,
  32                          struct net *net,
  33                          struct nf_conntrack_tuple *tuple)
  34 {
  35         const struct icmp6hdr *hp;
  36         struct icmp6hdr _hdr;
  37
  38         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  39         if (hp == NULL)
  40                 return false;
  41         tuple->dst.u.icmp.type = hp->icmp6_type;
  42         tuple->src.u.icmp.id = hp->icmp6_identifier;
  43         tuple->dst.u.icmp.code = hp->icmp6_code;
  44
  45         return true;
  46 }
  47
  48 /* Add 1; spaces filled with 0. */
  49 static const u_int8_t invmap[] = {
  50         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  51         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  52         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  53         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
  54 };
  55
  56 static const u_int8_t noct_valid_new[] = {
  57         [ICMPV6_MGM_QUERY - 130] = 1,
  58         [ICMPV6_MGM_REPORT - 130] = 1,
  59         [ICMPV6_MGM_REDUCTION - 130] = 1,
  60         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  61         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  62         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  63         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  64         [ICMPV6_MLD2_REPORT - 130] = 1
  65 };
  66
  67 bool nf_conntrack_invert_icmpv6_tuple(struct nf_conntrack_tuple *tuple,
  68                                       const struct nf_conntrack_tuple *orig)
  69 {
  70         int type = orig->dst.u.icmp.type - 128;
  71         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  72                 return false;
  73
  74         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  75         tuple->dst.u.icmp.type = invmap[type] - 1;
  76         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  77         return true;
  78 }
  79
  80 static unsigned int *icmpv6_get_timeouts(struct net *net)
  81 {
  82         return &nf_icmpv6_pernet(net)->timeout;
  83 }
  84
  85 /* Returns verdict for packet, or -1 for invalid. */
  86 int nf_conntrack_icmpv6_packet(struct nf_conn *ct,
  87                                struct sk_buff *skb,
  88                                enum ip_conntrack_info ctinfo,
  89                                const struct nf_hook_state *state)
  90 {
  91         unsigned int *timeout = nf_ct_timeout_lookup(ct);
  92         static const u8 valid_new[] = {
  93                 [ICMPV6_ECHO_REQUEST - 128] = 1,
  94                 [ICMPV6_NI_QUERY - 128] = 1
  95         };
  96
  97         if (state->pf != NFPROTO_IPV6)
  98                 return -NF_ACCEPT;
  99
 100         if (!nf_ct_is_confirmed(ct)) {
 101                 int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 102
 103                 if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 104                         /* Can't create a new ICMPv6 `conn' with this. */
 105                         pr_debug("icmpv6: can't create new conn with type %u\n",
 106                                  type + 128);
 107                         nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 108                         return -NF_ACCEPT;
 109                 }
 110         }
 111
 112         if (!timeout)
 113                 timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 114
 115         /* Do not immediately delete the connection after the first
 116            successful reply to avoid excessive conntrackd traffic
 117            and also to handle correctly ICMP echo reply duplicates. */
 118         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 119
 120         return NF_ACCEPT;
 121 }
 122
 123
 124 static void icmpv6_error_log(const struct sk_buff *skb,
 125                              const struct nf_hook_state *state,
 126                              const char *msg)
 127 {
 128         nf_l4proto_log_invalid(skb, state->net, state->pf,
 129                                IPPROTO_ICMPV6, "%s", msg);
 130 }
 131
 132 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 133                               struct sk_buff *skb,
 134                               unsigned int dataoff,
 135                               const struct nf_hook_state *state)
 136 {
 137         union nf_inet_addr outer_daddr;
 138         const struct icmp6hdr *icmp6h;
 139         struct icmp6hdr _ih;
 140         int type;
 141
 142         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 143         if (icmp6h == NULL) {
 144                 icmpv6_error_log(skb, state, "short packet");
 145                 return -NF_ACCEPT;
 146         }
 147
 148         if (state->hook == NF_INET_PRE_ROUTING &&
 149             state->net->ct.sysctl_checksum &&
 150             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 151                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 152                 return -NF_ACCEPT;
 153         }
 154
 155         type = icmp6h->icmp6_type - 130;
 156         if (type >= 0 && type < sizeof(noct_valid_new) &&
 157             noct_valid_new[type]) {
 158                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 159                 return NF_ACCEPT;
 160         }
 161
 162         /* is not error message ? */
 163         if (icmp6h->icmp6_type >= 128)
 164                 return NF_ACCEPT;
 165
 166         memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 167                sizeof(outer_daddr.ip6));
 168         dataoff += sizeof(*icmp6h);
 169         return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 170                                        IPPROTO_ICMPV6, &outer_daddr);
 171 }
 172
 173 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 174
 175 #include <linux/netfilter/nfnetlink.h>
 176 #include <linux/netfilter/nfnetlink_conntrack.h>
 177 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 178                                   const struct nf_conntrack_tuple *t)
 179 {
 180         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 181             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 182             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 183                 goto nla_put_failure;
 184         return 0;
 185
 186 nla_put_failure:
 187         return -1;
 188 }
 189
 190 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 191         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 192         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 193         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 194 };
 195
 196 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 197                                 struct nf_conntrack_tuple *tuple)
 198 {
 199         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 200             !tb[CTA_PROTO_ICMPV6_CODE] ||
 201             !tb[CTA_PROTO_ICMPV6_ID])
 202                 return -EINVAL;
 203
 204         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 205         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 206         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 207
 208         if (tuple->dst.u.icmp.type < 128 ||
 209             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 210             !invmap[tuple->dst.u.icmp.type - 128])
 211                 return -EINVAL;
 212
 213         return 0;
 214 }
 215
 216 static unsigned int icmpv6_nlattr_tuple_size(void)
 217 {
 218         static unsigned int size __read_mostly;
 219
 220         if (!size)
 221                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 222
 223         return size;
 224 }
 225 #endif
 226
 227 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 228
 229 #include <linux/netfilter/nfnetlink.h>
 230 #include <linux/netfilter/nfnetlink_cttimeout.h>
 231
 232 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 233                                         struct net *net, void *data)
 234 {
 235         unsigned int *timeout = data;
 236         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 237
 238         if (!timeout)
 239                 timeout = icmpv6_get_timeouts(net);
 240         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 241                 *timeout =
 242                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 243         } else {
 244                 /* Set default ICMPv6 timeout. */
 245                 *timeout = in->timeout;
 246         }
 247         return 0;
 248 }
 249
 250 static int
 251 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 252 {
 253         const unsigned int *timeout = data;
 254
 255         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 256                 goto nla_put_failure;
 257         return 0;
 258
 259 nla_put_failure:
 260         return -ENOSPC;
 261 }
 262
 263 static const struct nla_policy
 264 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 265         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 266 };
 267 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 268
 269 void nf_conntrack_icmpv6_init_net(struct net *net)
 270 {
 271         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 272
 273         in->timeout = nf_ct_icmpv6_timeout;
 274 }
 275
 276 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 277 {
 278         .l4proto                = IPPROTO_ICMPV6,
 279 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 280         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 281         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 282         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 283         .nla_policy             = icmpv6_nla_policy,
 284 #endif
 285 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 286         .ctnl_timeout           = {
 287                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 288                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 289                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 290                 .obj_size       = sizeof(unsigned int),
 291                 .nla_policy     = icmpv6_timeout_nla_policy,
 292         },
 293 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 294 };