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