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 <net/dst.h> 15 #include <net/xfrm.h> 16 #include <net/ip.h> 17 18 static struct xfrm_policy_afinfo xfrm4_policy_afinfo; 19 20 static struct dst_entry *xfrm4_dst_lookup(struct net *net, int tos, 21 xfrm_address_t *saddr, 22 xfrm_address_t *daddr) 23 { 24 struct flowi fl = { 25 .nl_u = { 26 .ip4_u = { 27 .tos = tos, 28 .daddr = daddr->a4, 29 }, 30 }, 31 }; 32 struct dst_entry *dst; 33 struct rtable *rt; 34 int err; 35 36 if (saddr) 37 fl.fl4_src = saddr->a4; 38 39 err = __ip_route_output_key(net, &rt, &fl); 40 dst = &rt->dst; 41 if (err) 42 dst = ERR_PTR(err); 43 return dst; 44 } 45 46 static int xfrm4_get_saddr(struct net *net, 47 xfrm_address_t *saddr, xfrm_address_t *daddr) 48 { 49 struct dst_entry *dst; 50 struct rtable *rt; 51 52 dst = xfrm4_dst_lookup(net, 0, NULL, daddr); 53 if (IS_ERR(dst)) 54 return -EHOSTUNREACH; 55 56 rt = (struct rtable *)dst; 57 saddr->a4 = rt->rt_src; 58 dst_release(dst); 59 return 0; 60 } 61 62 static int xfrm4_get_tos(struct flowi *fl) 63 { 64 return fl->fl4_tos; 65 } 66 67 static int xfrm4_init_path(struct xfrm_dst *path, struct dst_entry *dst, 68 int nfheader_len) 69 { 70 return 0; 71 } 72 73 static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev, 74 struct flowi *fl) 75 { 76 struct rtable *rt = (struct rtable *)xdst->route; 77 78 xdst->u.rt.fl = *fl; 79 80 xdst->u.dst.dev = dev; 81 dev_hold(dev); 82 83 xdst->u.rt.idev = in_dev_get(dev); 84 if (!xdst->u.rt.idev) 85 return -ENODEV; 86 87 xdst->u.rt.peer = rt->peer; 88 if (rt->peer) 89 atomic_inc(&rt->peer->refcnt); 90 91 /* Sheit... I remember I did this right. Apparently, 92 * it was magically lost, so this code needs audit */ 93 xdst->u.rt.rt_flags = rt->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST | 94 RTCF_LOCAL); 95 xdst->u.rt.rt_type = rt->rt_type; 96 xdst->u.rt.rt_src = rt->rt_src; 97 xdst->u.rt.rt_dst = rt->rt_dst; 98 xdst->u.rt.rt_gateway = rt->rt_gateway; 99 xdst->u.rt.rt_spec_dst = rt->rt_spec_dst; 100 101 return 0; 102 } 103 104 static void 105 _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse) 106 { 107 struct iphdr *iph = ip_hdr(skb); 108 u8 *xprth = skb_network_header(skb) + iph->ihl * 4; 109 110 memset(fl, 0, sizeof(struct flowi)); 111 fl->mark = skb->mark; 112 113 if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) { 114 switch (iph->protocol) { 115 case IPPROTO_UDP: 116 case IPPROTO_UDPLITE: 117 case IPPROTO_TCP: 118 case IPPROTO_SCTP: 119 case IPPROTO_DCCP: 120 if (xprth + 4 < skb->data || 121 pskb_may_pull(skb, xprth + 4 - skb->data)) { 122 __be16 *ports = (__be16 *)xprth; 123 124 fl->fl_ip_sport = ports[!!reverse]; 125 fl->fl_ip_dport = ports[!reverse]; 126 } 127 break; 128 129 case IPPROTO_ICMP: 130 if (pskb_may_pull(skb, xprth + 2 - skb->data)) { 131 u8 *icmp = xprth; 132 133 fl->fl_icmp_type = icmp[0]; 134 fl->fl_icmp_code = icmp[1]; 135 } 136 break; 137 138 case IPPROTO_ESP: 139 if (pskb_may_pull(skb, xprth + 4 - skb->data)) { 140 __be32 *ehdr = (__be32 *)xprth; 141 142 fl->fl_ipsec_spi = ehdr[0]; 143 } 144 break; 145 146 case IPPROTO_AH: 147 if (pskb_may_pull(skb, xprth + 8 - skb->data)) { 148 __be32 *ah_hdr = (__be32*)xprth; 149 150 fl->fl_ipsec_spi = ah_hdr[1]; 151 } 152 break; 153 154 case IPPROTO_COMP: 155 if (pskb_may_pull(skb, xprth + 4 - skb->data)) { 156 __be16 *ipcomp_hdr = (__be16 *)xprth; 157 158 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1])); 159 } 160 break; 161 default: 162 fl->fl_ipsec_spi = 0; 163 break; 164 } 165 } 166 fl->proto = iph->protocol; 167 fl->fl4_dst = reverse ? iph->saddr : iph->daddr; 168 fl->fl4_src = reverse ? iph->daddr : iph->saddr; 169 fl->fl4_tos = iph->tos; 170 } 171 172 static inline int xfrm4_garbage_collect(struct dst_ops *ops) 173 { 174 struct net *net = container_of(ops, struct net, xfrm.xfrm4_dst_ops); 175 176 xfrm4_policy_afinfo.garbage_collect(net); 177 return (atomic_read(&ops->entries) > ops->gc_thresh * 2); 178 } 179 180 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu) 181 { 182 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 183 struct dst_entry *path = xdst->route; 184 185 path->ops->update_pmtu(path, mtu); 186 } 187 188 static void xfrm4_dst_destroy(struct dst_entry *dst) 189 { 190 struct xfrm_dst *xdst = (struct xfrm_dst *)dst; 191 192 if (likely(xdst->u.rt.idev)) 193 in_dev_put(xdst->u.rt.idev); 194 if (likely(xdst->u.rt.peer)) 195 inet_putpeer(xdst->u.rt.peer); 196 xfrm_dst_destroy(xdst); 197 } 198 199 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev, 200 int unregister) 201 { 202 struct xfrm_dst *xdst; 203 204 if (!unregister) 205 return; 206 207 xdst = (struct xfrm_dst *)dst; 208 if (xdst->u.rt.idev->dev == dev) { 209 struct in_device *loopback_idev = 210 in_dev_get(dev_net(dev)->loopback_dev); 211 BUG_ON(!loopback_idev); 212 213 do { 214 in_dev_put(xdst->u.rt.idev); 215 xdst->u.rt.idev = loopback_idev; 216 in_dev_hold(loopback_idev); 217 xdst = (struct xfrm_dst *)xdst->u.dst.child; 218 } while (xdst->u.dst.xfrm); 219 220 __in_dev_put(loopback_idev); 221 } 222 223 xfrm_dst_ifdown(dst, dev); 224 } 225 226 static struct dst_ops xfrm4_dst_ops = { 227 .family = AF_INET, 228 .protocol = cpu_to_be16(ETH_P_IP), 229 .gc = xfrm4_garbage_collect, 230 .update_pmtu = xfrm4_update_pmtu, 231 .destroy = xfrm4_dst_destroy, 232 .ifdown = xfrm4_dst_ifdown, 233 .local_out = __ip_local_out, 234 .gc_thresh = 1024, 235 .entries = ATOMIC_INIT(0), 236 }; 237 238 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = { 239 .family = AF_INET, 240 .dst_ops = &xfrm4_dst_ops, 241 .dst_lookup = xfrm4_dst_lookup, 242 .get_saddr = xfrm4_get_saddr, 243 .decode_session = _decode_session4, 244 .get_tos = xfrm4_get_tos, 245 .init_path = xfrm4_init_path, 246 .fill_dst = xfrm4_fill_dst, 247 }; 248 249 #ifdef CONFIG_SYSCTL 250 static struct ctl_table xfrm4_policy_table[] = { 251 { 252 .procname = "xfrm4_gc_thresh", 253 .data = &init_net.xfrm.xfrm4_dst_ops.gc_thresh, 254 .maxlen = sizeof(int), 255 .mode = 0644, 256 .proc_handler = proc_dointvec, 257 }, 258 { } 259 }; 260 261 static struct ctl_table_header *sysctl_hdr; 262 #endif 263 264 static void __init xfrm4_policy_init(void) 265 { 266 xfrm_policy_register_afinfo(&xfrm4_policy_afinfo); 267 } 268 269 static void __exit xfrm4_policy_fini(void) 270 { 271 #ifdef CONFIG_SYSCTL 272 if (sysctl_hdr) 273 unregister_net_sysctl_table(sysctl_hdr); 274 #endif 275 xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo); 276 } 277 278 void __init xfrm4_init(int rt_max_size) 279 { 280 /* 281 * Select a default value for the gc_thresh based on the main route 282 * table hash size. It seems to me the worst case scenario is when 283 * we have ipsec operating in transport mode, in which we create a 284 * dst_entry per socket. The xfrm gc algorithm starts trying to remove 285 * entries at gc_thresh, and prevents new allocations as 2*gc_thresh 286 * so lets set an initial xfrm gc_thresh value at the rt_max_size/2. 287 * That will let us store an ipsec connection per route table entry, 288 * and start cleaning when were 1/2 full 289 */ 290 xfrm4_dst_ops.gc_thresh = rt_max_size/2; 291 292 xfrm4_state_init(); 293 xfrm4_policy_init(); 294 #ifdef CONFIG_SYSCTL 295 sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path, 296 xfrm4_policy_table); 297 #endif 298 } 299 300