1 // SPDX-License-Identifier: GPL-2.0-only 2 /* (C) 1999-2001 Paul `Rusty' Russell 3 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> 4 * (C) 2006-2012 Patrick McHardy <kaber@trash.net> 5 */ 6 7 #include <linux/types.h> 8 #include <linux/timer.h> 9 #include <linux/module.h> 10 #include <linux/udp.h> 11 #include <linux/seq_file.h> 12 #include <linux/skbuff.h> 13 #include <linux/ipv6.h> 14 #include <net/ip6_checksum.h> 15 #include <net/checksum.h> 16 17 #include <linux/netfilter.h> 18 #include <linux/netfilter_ipv4.h> 19 #include <linux/netfilter_ipv6.h> 20 #include <net/netfilter/nf_conntrack_l4proto.h> 21 #include <net/netfilter/nf_conntrack_ecache.h> 22 #include <net/netfilter/nf_conntrack_timeout.h> 23 #include <net/netfilter/nf_log.h> 24 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h> 25 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h> 26 27 static const unsigned int udp_timeouts[UDP_CT_MAX] = { 28 [UDP_CT_UNREPLIED] = 30*HZ, 29 [UDP_CT_REPLIED] = 120*HZ, 30 }; 31 32 static unsigned int *udp_get_timeouts(struct net *net) 33 { 34 return nf_udp_pernet(net)->timeouts; 35 } 36 37 static void udp_error_log(const struct sk_buff *skb, 38 const struct nf_hook_state *state, 39 const char *msg) 40 { 41 nf_l4proto_log_invalid(skb, state, IPPROTO_UDP, "%s", msg); 42 } 43 44 static bool udp_error(struct sk_buff *skb, 45 unsigned int dataoff, 46 const struct nf_hook_state *state) 47 { 48 unsigned int udplen = skb->len - dataoff; 49 const struct udphdr *hdr; 50 struct udphdr _hdr; 51 52 /* Header is too small? */ 53 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); 54 if (!hdr) { 55 udp_error_log(skb, state, "short packet"); 56 return true; 57 } 58 59 /* Truncated/malformed packets */ 60 if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) { 61 udp_error_log(skb, state, "truncated/malformed packet"); 62 return true; 63 } 64 65 /* Packet with no checksum */ 66 if (!hdr->check) 67 return false; 68 69 /* Checksum invalid? Ignore. 70 * We skip checking packets on the outgoing path 71 * because the checksum is assumed to be correct. 72 * FIXME: Source route IP option packets --RR */ 73 if (state->hook == NF_INET_PRE_ROUTING && 74 state->net->ct.sysctl_checksum && 75 nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) { 76 udp_error_log(skb, state, "bad checksum"); 77 return true; 78 } 79 80 return false; 81 } 82 83 /* Returns verdict for packet, and may modify conntracktype */ 84 int nf_conntrack_udp_packet(struct nf_conn *ct, 85 struct sk_buff *skb, 86 unsigned int dataoff, 87 enum ip_conntrack_info ctinfo, 88 const struct nf_hook_state *state) 89 { 90 unsigned int *timeouts; 91 92 if (udp_error(skb, dataoff, state)) 93 return -NF_ACCEPT; 94 95 timeouts = nf_ct_timeout_lookup(ct); 96 if (!timeouts) 97 timeouts = udp_get_timeouts(nf_ct_net(ct)); 98 99 if (!nf_ct_is_confirmed(ct)) 100 ct->proto.udp.stream_ts = 2 * HZ + jiffies; 101 102 /* If we've seen traffic both ways, this is some kind of UDP 103 * stream. Set Assured. 104 */ 105 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 106 unsigned long extra = timeouts[UDP_CT_UNREPLIED]; 107 108 /* Still active after two seconds? Extend timeout. */ 109 if (time_after(jiffies, ct->proto.udp.stream_ts)) 110 extra = timeouts[UDP_CT_REPLIED]; 111 112 nf_ct_refresh_acct(ct, ctinfo, skb, extra); 113 114 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */ 115 if (unlikely((ct->status & IPS_NAT_CLASH))) 116 return NF_ACCEPT; 117 118 /* Also, more likely to be important, and not a probe */ 119 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status)) 120 nf_conntrack_event_cache(IPCT_ASSURED, ct); 121 } else { 122 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]); 123 } 124 return NF_ACCEPT; 125 } 126 127 #ifdef CONFIG_NF_CT_PROTO_UDPLITE 128 static void udplite_error_log(const struct sk_buff *skb, 129 const struct nf_hook_state *state, 130 const char *msg) 131 { 132 nf_l4proto_log_invalid(skb, state, IPPROTO_UDPLITE, "%s", msg); 133 } 134 135 static bool udplite_error(struct sk_buff *skb, 136 unsigned int dataoff, 137 const struct nf_hook_state *state) 138 { 139 unsigned int udplen = skb->len - dataoff; 140 const struct udphdr *hdr; 141 struct udphdr _hdr; 142 unsigned int cscov; 143 144 /* Header is too small? */ 145 hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr); 146 if (!hdr) { 147 udplite_error_log(skb, state, "short packet"); 148 return true; 149 } 150 151 cscov = ntohs(hdr->len); 152 if (cscov == 0) { 153 cscov = udplen; 154 } else if (cscov < sizeof(*hdr) || cscov > udplen) { 155 udplite_error_log(skb, state, "invalid checksum coverage"); 156 return true; 157 } 158 159 /* UDPLITE mandates checksums */ 160 if (!hdr->check) { 161 udplite_error_log(skb, state, "checksum missing"); 162 return true; 163 } 164 165 /* Checksum invalid? Ignore. */ 166 if (state->hook == NF_INET_PRE_ROUTING && 167 state->net->ct.sysctl_checksum && 168 nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP, 169 state->pf)) { 170 udplite_error_log(skb, state, "bad checksum"); 171 return true; 172 } 173 174 return false; 175 } 176 177 /* Returns verdict for packet, and may modify conntracktype */ 178 int nf_conntrack_udplite_packet(struct nf_conn *ct, 179 struct sk_buff *skb, 180 unsigned int dataoff, 181 enum ip_conntrack_info ctinfo, 182 const struct nf_hook_state *state) 183 { 184 unsigned int *timeouts; 185 186 if (udplite_error(skb, dataoff, state)) 187 return -NF_ACCEPT; 188 189 timeouts = nf_ct_timeout_lookup(ct); 190 if (!timeouts) 191 timeouts = udp_get_timeouts(nf_ct_net(ct)); 192 193 /* If we've seen traffic both ways, this is some kind of UDP 194 stream. Extend timeout. */ 195 if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) { 196 nf_ct_refresh_acct(ct, ctinfo, skb, 197 timeouts[UDP_CT_REPLIED]); 198 199 if (unlikely((ct->status & IPS_NAT_CLASH))) 200 return NF_ACCEPT; 201 202 /* Also, more likely to be important, and not a probe */ 203 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status)) 204 nf_conntrack_event_cache(IPCT_ASSURED, ct); 205 } else { 206 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]); 207 } 208 return NF_ACCEPT; 209 } 210 #endif 211 212 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 213 214 #include <linux/netfilter/nfnetlink.h> 215 #include <linux/netfilter/nfnetlink_cttimeout.h> 216 217 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[], 218 struct net *net, void *data) 219 { 220 unsigned int *timeouts = data; 221 struct nf_udp_net *un = nf_udp_pernet(net); 222 223 if (!timeouts) 224 timeouts = un->timeouts; 225 226 /* set default timeouts for UDP. */ 227 timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED]; 228 timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED]; 229 230 if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) { 231 timeouts[UDP_CT_UNREPLIED] = 232 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ; 233 } 234 if (tb[CTA_TIMEOUT_UDP_REPLIED]) { 235 timeouts[UDP_CT_REPLIED] = 236 ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ; 237 } 238 return 0; 239 } 240 241 static int 242 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data) 243 { 244 const unsigned int *timeouts = data; 245 246 if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED, 247 htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) || 248 nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED, 249 htonl(timeouts[UDP_CT_REPLIED] / HZ))) 250 goto nla_put_failure; 251 return 0; 252 253 nla_put_failure: 254 return -ENOSPC; 255 } 256 257 static const struct nla_policy 258 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = { 259 [CTA_TIMEOUT_UDP_UNREPLIED] = { .type = NLA_U32 }, 260 [CTA_TIMEOUT_UDP_REPLIED] = { .type = NLA_U32 }, 261 }; 262 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 263 264 void nf_conntrack_udp_init_net(struct net *net) 265 { 266 struct nf_udp_net *un = nf_udp_pernet(net); 267 int i; 268 269 for (i = 0; i < UDP_CT_MAX; i++) 270 un->timeouts[i] = udp_timeouts[i]; 271 272 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE) 273 un->offload_timeout = 30 * HZ; 274 un->offload_pickup = 30 * HZ; 275 #endif 276 } 277 278 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp = 279 { 280 .l4proto = IPPROTO_UDP, 281 .allow_clash = true, 282 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 283 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, 284 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, 285 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, 286 .nla_policy = nf_ct_port_nla_policy, 287 #endif 288 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 289 .ctnl_timeout = { 290 .nlattr_to_obj = udp_timeout_nlattr_to_obj, 291 .obj_to_nlattr = udp_timeout_obj_to_nlattr, 292 .nlattr_max = CTA_TIMEOUT_UDP_MAX, 293 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX, 294 .nla_policy = udp_timeout_nla_policy, 295 }, 296 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 297 }; 298 299 #ifdef CONFIG_NF_CT_PROTO_UDPLITE 300 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite = 301 { 302 .l4proto = IPPROTO_UDPLITE, 303 .allow_clash = true, 304 #if IS_ENABLED(CONFIG_NF_CT_NETLINK) 305 .tuple_to_nlattr = nf_ct_port_tuple_to_nlattr, 306 .nlattr_to_tuple = nf_ct_port_nlattr_to_tuple, 307 .nlattr_tuple_size = nf_ct_port_nlattr_tuple_size, 308 .nla_policy = nf_ct_port_nla_policy, 309 #endif 310 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT 311 .ctnl_timeout = { 312 .nlattr_to_obj = udp_timeout_nlattr_to_obj, 313 .obj_to_nlattr = udp_timeout_obj_to_nlattr, 314 .nlattr_max = CTA_TIMEOUT_UDP_MAX, 315 .obj_size = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX, 316 .nla_policy = udp_timeout_nla_policy, 317 }, 318 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ 319 }; 320 #endif 321