1 /* 2 * xfrm4_policy.c 3 * 4 * Changes: 5 * Kazunori MIYAZAWA @USAGI 6 * YOSHIFUJI Hideaki @USAGI 7 * Split up af-specific portion 8 * 9 */ 10 11 #include <linux/err.h> 12 #include <linux/kernel.h> 13 #include <linux/inetdevice.h> 14 #include <linux/if_tunnel.h> 15 #include <net/dst.h> 16 #include <net/xfrm.h> 17 #include <net/ip.h> 18 19 static struct xfrm_policy_afinfo xfrm4_policy_afinfo; 20 21 static struct dst_entry *__xfrm4_dst_lookup(struct net *net, struct flowi4 *fl4, 22 int tos, 23 const xfrm_address_t *saddr, 24 const xfrm_address_t *daddr) 25 { 26 struct rtable *rt; 27 28 memset(fl4, 0, sizeof(*fl4)); 29 fl4->daddr = daddr->a4; 30 fl4->flowi4_tos = tos; 31 if (saddr) 32 fl4->saddr = saddr->a4; 33 34 rt = __ip_route_output_key(net, fl4); 35 if (!IS_ERR(rt)) 36 return &rt->dst; 37 38 return ERR_CAST(rt); 39 } 40 41 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, 42 const xfrm_address_t *saddr, 43 const xfrm_address_t *daddr) 44 { 45 struct flowi4 fl4; 46 47 return __xfrm4_dst_lookup(net, &fl4, tos, saddr, daddr); 48 } 49 50 static int xfrm4_get_saddr(struct net *net, 51 xfrm_address_t *saddr, xfrm_address_t *daddr) 52 { 53 struct dst_entry *dst; 54 struct flowi4 fl4; 55 56 dst = __xfrm4_dst_lookup(net, &fl4, 0, NULL, daddr); 57 if (IS_ERR(dst)) 58 return -EHOSTUNREACH; 59 60 saddr->a4 = fl4.saddr; 61 dst_release(dst); 62 return 0; 63 } 64 65 static int xfrm4_get_tos(const struct flowi *fl) 66 { 67 return IPTOS_RT_MASK & fl->u.ip4.flowi4_tos; /* Strip ECN bits */ 68 } 69 70 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst, 71 int nfheader_len) 72 { 73 return 0; 74 } 75 76 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev, 77 const struct flowi *fl) 78 { 79 struct rtable *rt = (struct rtable *)xdst->route; 80 const struct flowi4 *fl4 = &fl->u.ip4; 81 82 xdst->u.rt.rt_key_dst = fl4->daddr; 83 xdst->u.rt.rt_key_src = fl4->saddr; 84 xdst->u.rt.rt_key_tos = fl4->flowi4_tos; 85 xdst->u.rt.rt_route_iif = fl4->flowi4_iif; 86 xdst->u.rt.rt_iif = fl4->flowi4_iif; 87 xdst->u.rt.rt_oif = fl4->flowi4_oif; 88 xdst->u.rt.rt_mark = fl4->flowi4_mark; 89 90 xdst->u.dst.dev = dev; 91 dev_hold(dev); 92 93 xdst->u.rt.peer = rt->peer; 94 if (rt->peer) 95 atomic_inc(&rt->peer->refcnt); 96 97 /* Sheit... I remember I did this right. Apparently, 98 * it was magically lost, so this code needs audit */ 99 xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | 100 RTCF_LOCAL); 101 xdst->u.rt.rt_type = rt->rt_type; 102 xdst->u.rt.rt_src = rt->rt_src; 103 xdst->u.rt.rt_dst = rt->rt_dst; 104 xdst->u.rt.rt_gateway = rt->rt_gateway; 105 xdst->u.rt.rt_spec_dst = rt->rt_spec_dst; 106 107 return 0; 108 } 109 110 static void 111 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 112 { 113 const struct iphdr *iph = ip_hdr(skb); 114 u8 *xprth = skb_network_header(skb) + iph->ihl * 4; 115 struct flowi4 *fl4 = &fl->u.ip4; 116 117 memset(fl4, 0, sizeof(struct flowi4)); 118 fl4->flowi4_mark = skb->mark; 119 120 if (!ip_is_fragment(iph)) { 121 switch (iph->protocol) { 122 case IPPROTO_UDP: 123 case IPPROTO_UDPLITE: 124 case IPPROTO_TCP: 125 case IPPROTO_SCTP: 126 case IPPROTO_DCCP: 127 if (xprth + 4 < skb->data || 128 pskb_may_pull(skb, xprth + 4 - skb->data)) { 129 __be16 *ports = (__be16 *)xprth; 130 131 fl4->fl4_sport = ports[!!reverse]; 132 fl4->fl4_dport = ports[!reverse]; 133 } 134 break; 135 136 case IPPROTO_ICMP: 137 if (pskb_may_pull(skb, xprth + 2 - skb->data)) { 138 u8 *icmp = xprth; 139 140 fl4->fl4_icmp_type = icmp[0]; 141 fl4->fl4_icmp_code = icmp[1]; 142 } 143 break; 144 145 case IPPROTO_ESP: 146 if (pskb_may_pull(skb, xprth + 4 - skb->data)) { 147 __be32 *ehdr = (__be32 *)xprth; 148 149 fl4->fl4_ipsec_spi = ehdr[0]; 150 } 151 break; 152 153 case IPPROTO_AH: 154 if (pskb_may_pull(skb, xprth + 8 - skb->data)) { 155 __be32 *ah_hdr = (__be32*)xprth; 156 157 fl4->fl4_ipsec_spi = ah_hdr[1]; 158 } 159 break; 160 161 case IPPROTO_COMP: 162 if (pskb_may_pull(skb, xprth + 4 - skb->data)) { 163 __be16 *ipcomp_hdr = (__be16 *)xprth; 164 165 fl4->fl4_ipsec_spi = htonl(ntohs(ipcomp_hdr[1])); 166 } 167 break; 168 169 case IPPROTO_GRE: 170 if (pskb_may_pull(skb, xprth + 12 - skb->data)) { 171 __be16 *greflags = (__be16 *)xprth; 172 __be32 *gre_hdr = (__be32 *)xprth; 173 174 if (greflags[0] & GRE_KEY) { 175 if (greflags[0] & GRE_CSUM) 176 gre_hdr++; 177 fl4->fl4_gre_key = gre_hdr[1]; 178 } 179 } 180 break; 181 182 default: 183 fl4->fl4_ipsec_spi = 0; 184 break; 185 } 186 } 187 fl4->flowi4_proto = iph->protocol; 188 fl4->daddr = reverse ? iph->saddr : iph->daddr; 189 fl4->saddr = reverse ? iph->daddr : iph->saddr; 190 fl4->flowi4_tos = iph->tos; 191 } 192 193 static inline int xfrm4_garbage_collect(struct dst_ops *ops) 194 { 195 struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops); 196 197 xfrm4_policy_afinfo.garbage_collect(net); 198 return (dst_entries_get_slow(ops) > ops->gc_thresh * 2); 199 } 200 201 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu) 202 { 203 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 204 struct dst_entry *path = xdst->route; 205 206 path->ops->update_pmtu(path, mtu); 207 } 208 209 static void xfrm4_dst_destroy(struct dst_entry *dst) 210 { 211 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 212 213 dst_destroy_metrics_generic(dst); 214 215 if (likely(xdst->u.rt.peer)) 216 inet_putpeer(xdst->u.rt.peer); 217 218 xfrm_dst_destroy(xdst); 219 } 220 221 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev, 222 int unregister) 223 { 224 if (!unregister) 225 return; 226 227 xfrm_dst_ifdown(dst, dev); 228 } 229 230 static struct dst_ops xfrm4_dst_ops = { 231 .family = AF_INET, 232 .protocol = cpu_to_be16(ETH_P_IP), 233 .gc = xfrm4_garbage_collect, 234 .update_pmtu = xfrm4_update_pmtu, 235 .cow_metrics = dst_cow_metrics_generic, 236 .destroy = xfrm4_dst_destroy, 237 .ifdown = xfrm4_dst_ifdown, 238 .local_out = __ip_local_out, 239 .gc_thresh = 1024, 240 }; 241 242 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = { 243 .family = AF_INET, 244 .dst_ops = &xfrm4_dst_ops, 245 .dst_lookup = xfrm4_dst_lookup, 246 .get_saddr = xfrm4_get_saddr, 247 .decode_session = _decode_session4, 248 .get_tos = xfrm4_get_tos, 249 .init_path = xfrm4_init_path, 250 .fill_dst = xfrm4_fill_dst, 251 .blackhole_route = ipv4_blackhole_route, 252 }; 253 254 #ifdef CONFIG_SYSCTL 255 static struct ctl_table xfrm4_policy_table[] = { 256 { 257 .procname = "xfrm4_gc_thresh", 258 .data = &init_net.xfrm.xfrm4_dst_ops.gc_thresh, 259 .maxlen = sizeof(int), 260 .mode = 0644, 261 .proc_handler = proc_dointvec, 262 }, 263 { } 264 }; 265 266 static struct ctl_table_header *sysctl_hdr; 267 #endif 268 269 static void __init xfrm4_policy_init(void) 270 { 271 xfrm_policy_register_afinfo(&xfrm4_policy_afinfo); 272 } 273 274 static void __exit xfrm4_policy_fini(void) 275 { 276 #ifdef CONFIG_SYSCTL 277 if (sysctl_hdr) 278 unregister_net_sysctl_table(sysctl_hdr); 279 #endif 280 xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo); 281 } 282 283 void __init xfrm4_init(int rt_max_size) 284 { 285 /* 286 * Select a default value for the gc_thresh based on the main route 287 * table hash size. It seems to me the worst case scenario is when 288 * we have ipsec operating in transport mode, in which we create a 289 * dst_entry per socket. The xfrm gc algorithm starts trying to remove 290 * entries at gc_thresh, and prevents new allocations as 2*gc_thresh 291 * so lets set an initial xfrm gc_thresh value at the rt_max_size/2. 292 * That will let us store an ipsec connection per route table entry, 293 * and start cleaning when were 1/2 full 294 */ 295 xfrm4_dst_ops.gc_thresh = rt_max_size/2; 296 dst_entries_init(&xfrm4_dst_ops); 297 298 xfrm4_state_init(); 299 xfrm4_policy_init(); 300 #ifdef CONFIG_SYSCTL 301 sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path, 302 xfrm4_policy_table); 303 #endif 304 } 305 306