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