1 /* xfrm4_protocol.c - Generic xfrm protocol multiplexer. 2 * 3 * Copyright (C) 2013 secunet Security Networks AG 4 * 5 * Author: 6 * Steffen Klassert <steffen.klassert@secunet.com> 7 * 8 * Based on: 9 * net/ipv4/tunnel4.c 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License 13 * as published by the Free Software Foundation; either version 14 * 2 of the License, or (at your option) any later version. 15 */ 16 17 #include <linux/init.h> 18 #include <linux/mutex.h> 19 #include <linux/skbuff.h> 20 #include <net/icmp.h> 21 #include <net/ip.h> 22 #include <net/protocol.h> 23 #include <net/xfrm.h> 24 25 static struct xfrm4_protocol __rcu *esp4_handlers __read_mostly; 26 static struct xfrm4_protocol __rcu *ah4_handlers __read_mostly; 27 static struct xfrm4_protocol __rcu *ipcomp4_handlers __read_mostly; 28 static DEFINE_MUTEX(xfrm4_protocol_mutex); 29 30 static inline struct xfrm4_protocol __rcu **proto_handlers(u8 protocol) 31 { 32 switch (protocol) { 33 case IPPROTO_ESP: 34 return &esp4_handlers; 35 case IPPROTO_AH: 36 return &ah4_handlers; 37 case IPPROTO_COMP: 38 return &ipcomp4_handlers; 39 } 40 41 return NULL; 42 } 43 44 #define for_each_protocol_rcu(head, handler) \ 45 for (handler = rcu_dereference(head); \ 46 handler != NULL; \ 47 handler = rcu_dereference(handler->next)) \ 48 49 int xfrm4_rcv_cb(struct sk_buff *skb, u8 protocol, int err) 50 { 51 int ret; 52 struct xfrm4_protocol *handler; 53 54 for_each_protocol_rcu(*proto_handlers(protocol), handler) 55 if ((ret = handler->cb_handler(skb, err)) <= 0) 56 return ret; 57 58 return 0; 59 } 60 EXPORT_SYMBOL(xfrm4_rcv_cb); 61 62 int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi, 63 int encap_type) 64 { 65 int ret; 66 struct xfrm4_protocol *handler; 67 68 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL; 69 XFRM_SPI_SKB_CB(skb)->family = AF_INET; 70 XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr); 71 72 for_each_protocol_rcu(*proto_handlers(nexthdr), handler) 73 if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL) 74 return ret; 75 76 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); 77 78 kfree_skb(skb); 79 return 0; 80 } 81 EXPORT_SYMBOL(xfrm4_rcv_encap); 82 83 static int xfrm4_esp_rcv(struct sk_buff *skb) 84 { 85 int ret; 86 struct xfrm4_protocol *handler; 87 88 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL; 89 90 for_each_protocol_rcu(esp4_handlers, handler) 91 if ((ret = handler->handler(skb)) != -EINVAL) 92 return ret; 93 94 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); 95 96 kfree_skb(skb); 97 return 0; 98 } 99 100 static void xfrm4_esp_err(struct sk_buff *skb, u32 info) 101 { 102 struct xfrm4_protocol *handler; 103 104 for_each_protocol_rcu(esp4_handlers, handler) 105 if (!handler->err_handler(skb, info)) 106 break; 107 } 108 109 static int xfrm4_ah_rcv(struct sk_buff *skb) 110 { 111 int ret; 112 struct xfrm4_protocol *handler; 113 114 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL; 115 116 for_each_protocol_rcu(ah4_handlers, handler) 117 if ((ret = handler->handler(skb)) != -EINVAL) 118 return ret;; 119 120 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); 121 122 kfree_skb(skb); 123 return 0; 124 } 125 126 static void xfrm4_ah_err(struct sk_buff *skb, u32 info) 127 { 128 struct xfrm4_protocol *handler; 129 130 for_each_protocol_rcu(ah4_handlers, handler) 131 if (!handler->err_handler(skb, info)) 132 break; 133 } 134 135 static int xfrm4_ipcomp_rcv(struct sk_buff *skb) 136 { 137 int ret; 138 struct xfrm4_protocol *handler; 139 140 XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = NULL; 141 142 for_each_protocol_rcu(ipcomp4_handlers, handler) 143 if ((ret = handler->handler(skb)) != -EINVAL) 144 return ret; 145 146 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); 147 148 kfree_skb(skb); 149 return 0; 150 } 151 152 static void xfrm4_ipcomp_err(struct sk_buff *skb, u32 info) 153 { 154 struct xfrm4_protocol *handler; 155 156 for_each_protocol_rcu(ipcomp4_handlers, handler) 157 if (!handler->err_handler(skb, info)) 158 break; 159 } 160 161 static const struct net_protocol esp4_protocol = { 162 .handler = xfrm4_esp_rcv, 163 .err_handler = xfrm4_esp_err, 164 .no_policy = 1, 165 .netns_ok = 1, 166 }; 167 168 static const struct net_protocol ah4_protocol = { 169 .handler = xfrm4_ah_rcv, 170 .err_handler = xfrm4_ah_err, 171 .no_policy = 1, 172 .netns_ok = 1, 173 }; 174 175 static const struct net_protocol ipcomp4_protocol = { 176 .handler = xfrm4_ipcomp_rcv, 177 .err_handler = xfrm4_ipcomp_err, 178 .no_policy = 1, 179 .netns_ok = 1, 180 }; 181 182 static inline const struct net_protocol *netproto(unsigned char protocol) 183 { 184 switch (protocol) { 185 case IPPROTO_ESP: 186 return &esp4_protocol; 187 case IPPROTO_AH: 188 return &ah4_protocol; 189 case IPPROTO_COMP: 190 return &ipcomp4_protocol; 191 } 192 193 return NULL; 194 } 195 196 int xfrm4_protocol_register(struct xfrm4_protocol *handler, 197 unsigned char protocol) 198 { 199 struct xfrm4_protocol __rcu **pprev; 200 struct xfrm4_protocol *t; 201 bool add_netproto = false; 202 203 int ret = -EEXIST; 204 int priority = handler->priority; 205 206 mutex_lock(&xfrm4_protocol_mutex); 207 208 if (!rcu_dereference_protected(*proto_handlers(protocol), 209 lockdep_is_held(&xfrm4_protocol_mutex))) 210 add_netproto = true; 211 212 for (pprev = proto_handlers(protocol); 213 (t = rcu_dereference_protected(*pprev, 214 lockdep_is_held(&xfrm4_protocol_mutex))) != NULL; 215 pprev = &t->next) { 216 if (t->priority < priority) 217 break; 218 if (t->priority == priority) 219 goto err; 220 } 221 222 handler->next = *pprev; 223 rcu_assign_pointer(*pprev, handler); 224 225 ret = 0; 226 227 err: 228 mutex_unlock(&xfrm4_protocol_mutex); 229 230 if (add_netproto) { 231 if (inet_add_protocol(netproto(protocol), protocol)) { 232 pr_err("%s: can't add protocol\n", __func__); 233 ret = -EAGAIN; 234 } 235 } 236 237 return ret; 238 } 239 EXPORT_SYMBOL(xfrm4_protocol_register); 240 241 int xfrm4_protocol_deregister(struct xfrm4_protocol *handler, 242 unsigned char protocol) 243 { 244 struct xfrm4_protocol __rcu **pprev; 245 struct xfrm4_protocol *t; 246 int ret = -ENOENT; 247 248 mutex_lock(&xfrm4_protocol_mutex); 249 250 for (pprev = proto_handlers(protocol); 251 (t = rcu_dereference_protected(*pprev, 252 lockdep_is_held(&xfrm4_protocol_mutex))) != NULL; 253 pprev = &t->next) { 254 if (t == handler) { 255 *pprev = handler->next; 256 ret = 0; 257 break; 258 } 259 } 260 261 if (!rcu_dereference_protected(*proto_handlers(protocol), 262 lockdep_is_held(&xfrm4_protocol_mutex))) { 263 if (inet_del_protocol(netproto(protocol), protocol) < 0) { 264 pr_err("%s: can't remove protocol\n", __func__); 265 ret = -EAGAIN; 266 } 267 } 268 269 mutex_unlock(&xfrm4_protocol_mutex); 270 271 synchronize_net(); 272 273 return ret; 274 } 275 EXPORT_SYMBOL(xfrm4_protocol_deregister); 276