1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * net/core/dst.c Protocol independent destination cache. 4 * 5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 6 * 7 */ 8 9 #include <linux/bitops.h> 10 #include <linux/errno.h> 11 #include <linux/init.h> 12 #include <linux/kernel.h> 13 #include <linux/workqueue.h> 14 #include <linux/mm.h> 15 #include <linux/module.h> 16 #include <linux/slab.h> 17 #include <linux/netdevice.h> 18 #include <linux/skbuff.h> 19 #include <linux/string.h> 20 #include <linux/types.h> 21 #include <net/net_namespace.h> 22 #include <linux/sched.h> 23 #include <linux/prefetch.h> 24 #include <net/lwtunnel.h> 25 #include <net/xfrm.h> 26 27 #include <net/dst.h> 28 #include <net/dst_metadata.h> 29 30 int dst_discard_out(struct net *net, struct sock *sk, struct sk_buff *skb) 31 { 32 kfree_skb(skb); 33 return 0; 34 } 35 EXPORT_SYMBOL(dst_discard_out); 36 37 const struct dst_metrics dst_default_metrics = { 38 /* This initializer is needed to force linker to place this variable 39 * into const section. Otherwise it might end into bss section. 40 * We really want to avoid false sharing on this variable, and catch 41 * any writes on it. 42 */ 43 .refcnt = REFCOUNT_INIT(1), 44 }; 45 EXPORT_SYMBOL(dst_default_metrics); 46 47 void dst_init(struct dst_entry *dst, struct dst_ops *ops, 48 struct net_device *dev, int initial_ref, int initial_obsolete, 49 unsigned short flags) 50 { 51 dst->dev = dev; 52 netdev_hold(dev, &dst->dev_tracker, GFP_ATOMIC); 53 dst->ops = ops; 54 dst_init_metrics(dst, dst_default_metrics.metrics, true); 55 dst->expires = 0UL; 56 #ifdef CONFIG_XFRM 57 dst->xfrm = NULL; 58 #endif 59 dst->input = dst_discard; 60 dst->output = dst_discard_out; 61 dst->error = 0; 62 dst->obsolete = initial_obsolete; 63 dst->header_len = 0; 64 dst->trailer_len = 0; 65 #ifdef CONFIG_IP_ROUTE_CLASSID 66 dst->tclassid = 0; 67 #endif 68 dst->lwtstate = NULL; 69 rcuref_init(&dst->__rcuref, initial_ref); 70 INIT_LIST_HEAD(&dst->rt_uncached); 71 dst->__use = 0; 72 dst->lastuse = jiffies; 73 dst->flags = flags; 74 if (!(flags & DST_NOCOUNT)) 75 dst_entries_add(ops, 1); 76 } 77 EXPORT_SYMBOL(dst_init); 78 79 void *dst_alloc(struct dst_ops *ops, struct net_device *dev, 80 int initial_ref, int initial_obsolete, unsigned short flags) 81 { 82 struct dst_entry *dst; 83 84 if (ops->gc && 85 !(flags & DST_NOCOUNT) && 86 dst_entries_get_fast(ops) > ops->gc_thresh) 87 ops->gc(ops); 88 89 dst = kmem_cache_alloc(ops->kmem_cachep, GFP_ATOMIC); 90 if (!dst) 91 return NULL; 92 93 dst_init(dst, ops, dev, initial_ref, initial_obsolete, flags); 94 95 return dst; 96 } 97 EXPORT_SYMBOL(dst_alloc); 98 99 struct dst_entry *dst_destroy(struct dst_entry * dst) 100 { 101 struct dst_entry *child = NULL; 102 103 smp_rmb(); 104 105 #ifdef CONFIG_XFRM 106 if (dst->xfrm) { 107 struct xfrm_dst *xdst = (struct xfrm_dst *) dst; 108 109 child = xdst->child; 110 } 111 #endif 112 if (!(dst->flags & DST_NOCOUNT)) 113 dst_entries_add(dst->ops, -1); 114 115 if (dst->ops->destroy) 116 dst->ops->destroy(dst); 117 netdev_put(dst->dev, &dst->dev_tracker); 118 119 lwtstate_put(dst->lwtstate); 120 121 if (dst->flags & DST_METADATA) 122 metadata_dst_free((struct metadata_dst *)dst); 123 else 124 kmem_cache_free(dst->ops->kmem_cachep, dst); 125 126 dst = child; 127 if (dst) 128 dst_release_immediate(dst); 129 return NULL; 130 } 131 EXPORT_SYMBOL(dst_destroy); 132 133 static void dst_destroy_rcu(struct rcu_head *head) 134 { 135 struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); 136 137 dst = dst_destroy(dst); 138 } 139 140 /* Operations to mark dst as DEAD and clean up the net device referenced 141 * by dst: 142 * 1. put the dst under blackhole interface and discard all tx/rx packets 143 * on this route. 144 * 2. release the net_device 145 * This function should be called when removing routes from the fib tree 146 * in preparation for a NETDEV_DOWN/NETDEV_UNREGISTER event and also to 147 * make the next dst_ops->check() fail. 148 */ 149 void dst_dev_put(struct dst_entry *dst) 150 { 151 struct net_device *dev = dst->dev; 152 153 dst->obsolete = DST_OBSOLETE_DEAD; 154 if (dst->ops->ifdown) 155 dst->ops->ifdown(dst, dev); 156 dst->input = dst_discard; 157 dst->output = dst_discard_out; 158 dst->dev = blackhole_netdev; 159 netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker, 160 GFP_ATOMIC); 161 } 162 EXPORT_SYMBOL(dst_dev_put); 163 164 void dst_release(struct dst_entry *dst) 165 { 166 if (dst && rcuref_put(&dst->__rcuref)) 167 call_rcu_hurry(&dst->rcu_head, dst_destroy_rcu); 168 } 169 EXPORT_SYMBOL(dst_release); 170 171 void dst_release_immediate(struct dst_entry *dst) 172 { 173 if (dst && rcuref_put(&dst->__rcuref)) 174 dst_destroy(dst); 175 } 176 EXPORT_SYMBOL(dst_release_immediate); 177 178 u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old) 179 { 180 struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC); 181 182 if (p) { 183 struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old); 184 unsigned long prev, new; 185 186 refcount_set(&p->refcnt, 1); 187 memcpy(p->metrics, old_p->metrics, sizeof(p->metrics)); 188 189 new = (unsigned long) p; 190 prev = cmpxchg(&dst->_metrics, old, new); 191 192 if (prev != old) { 193 kfree(p); 194 p = (struct dst_metrics *)__DST_METRICS_PTR(prev); 195 if (prev & DST_METRICS_READ_ONLY) 196 p = NULL; 197 } else if (prev & DST_METRICS_REFCOUNTED) { 198 if (refcount_dec_and_test(&old_p->refcnt)) 199 kfree(old_p); 200 } 201 } 202 BUILD_BUG_ON(offsetof(struct dst_metrics, metrics) != 0); 203 return (u32 *)p; 204 } 205 EXPORT_SYMBOL(dst_cow_metrics_generic); 206 207 /* Caller asserts that dst_metrics_read_only(dst) is false. */ 208 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old) 209 { 210 unsigned long prev, new; 211 212 new = ((unsigned long) &dst_default_metrics) | DST_METRICS_READ_ONLY; 213 prev = cmpxchg(&dst->_metrics, old, new); 214 if (prev == old) 215 kfree(__DST_METRICS_PTR(old)); 216 } 217 EXPORT_SYMBOL(__dst_destroy_metrics_generic); 218 219 struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie) 220 { 221 return NULL; 222 } 223 224 u32 *dst_blackhole_cow_metrics(struct dst_entry *dst, unsigned long old) 225 { 226 return NULL; 227 } 228 229 struct neighbour *dst_blackhole_neigh_lookup(const struct dst_entry *dst, 230 struct sk_buff *skb, 231 const void *daddr) 232 { 233 return NULL; 234 } 235 236 void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk, 237 struct sk_buff *skb, u32 mtu, 238 bool confirm_neigh) 239 { 240 } 241 EXPORT_SYMBOL_GPL(dst_blackhole_update_pmtu); 242 243 void dst_blackhole_redirect(struct dst_entry *dst, struct sock *sk, 244 struct sk_buff *skb) 245 { 246 } 247 EXPORT_SYMBOL_GPL(dst_blackhole_redirect); 248 249 unsigned int dst_blackhole_mtu(const struct dst_entry *dst) 250 { 251 unsigned int mtu = dst_metric_raw(dst, RTAX_MTU); 252 253 return mtu ? : dst->dev->mtu; 254 } 255 EXPORT_SYMBOL_GPL(dst_blackhole_mtu); 256 257 static struct dst_ops dst_blackhole_ops = { 258 .family = AF_UNSPEC, 259 .neigh_lookup = dst_blackhole_neigh_lookup, 260 .check = dst_blackhole_check, 261 .cow_metrics = dst_blackhole_cow_metrics, 262 .update_pmtu = dst_blackhole_update_pmtu, 263 .redirect = dst_blackhole_redirect, 264 .mtu = dst_blackhole_mtu, 265 }; 266 267 static void __metadata_dst_init(struct metadata_dst *md_dst, 268 enum metadata_type type, u8 optslen) 269 { 270 struct dst_entry *dst; 271 272 dst = &md_dst->dst; 273 dst_init(dst, &dst_blackhole_ops, NULL, 1, DST_OBSOLETE_NONE, 274 DST_METADATA | DST_NOCOUNT); 275 memset(dst + 1, 0, sizeof(*md_dst) + optslen - sizeof(*dst)); 276 md_dst->type = type; 277 } 278 279 struct metadata_dst *metadata_dst_alloc(u8 optslen, enum metadata_type type, 280 gfp_t flags) 281 { 282 struct metadata_dst *md_dst; 283 284 md_dst = kmalloc(sizeof(*md_dst) + optslen, flags); 285 if (!md_dst) 286 return NULL; 287 288 __metadata_dst_init(md_dst, type, optslen); 289 290 return md_dst; 291 } 292 EXPORT_SYMBOL_GPL(metadata_dst_alloc); 293 294 void metadata_dst_free(struct metadata_dst *md_dst) 295 { 296 #ifdef CONFIG_DST_CACHE 297 if (md_dst->type == METADATA_IP_TUNNEL) 298 dst_cache_destroy(&md_dst->u.tun_info.dst_cache); 299 #endif 300 if (md_dst->type == METADATA_XFRM) 301 dst_release(md_dst->u.xfrm_info.dst_orig); 302 kfree(md_dst); 303 } 304 EXPORT_SYMBOL_GPL(metadata_dst_free); 305 306 struct metadata_dst __percpu * 307 metadata_dst_alloc_percpu(u8 optslen, enum metadata_type type, gfp_t flags) 308 { 309 int cpu; 310 struct metadata_dst __percpu *md_dst; 311 312 md_dst = __alloc_percpu_gfp(sizeof(struct metadata_dst) + optslen, 313 __alignof__(struct metadata_dst), flags); 314 if (!md_dst) 315 return NULL; 316 317 for_each_possible_cpu(cpu) 318 __metadata_dst_init(per_cpu_ptr(md_dst, cpu), type, optslen); 319 320 return md_dst; 321 } 322 EXPORT_SYMBOL_GPL(metadata_dst_alloc_percpu); 323 324 void metadata_dst_free_percpu(struct metadata_dst __percpu *md_dst) 325 { 326 int cpu; 327 328 for_each_possible_cpu(cpu) { 329 struct metadata_dst *one_md_dst = per_cpu_ptr(md_dst, cpu); 330 331 #ifdef CONFIG_DST_CACHE 332 if (one_md_dst->type == METADATA_IP_TUNNEL) 333 dst_cache_destroy(&one_md_dst->u.tun_info.dst_cache); 334 #endif 335 if (one_md_dst->type == METADATA_XFRM) 336 dst_release(one_md_dst->u.xfrm_info.dst_orig); 337 } 338 free_percpu(md_dst); 339 } 340 EXPORT_SYMBOL_GPL(metadata_dst_free_percpu); 341