1 /* 2 * Berkeley Packet Filter based traffic classifier 3 * 4 * Might be used to classify traffic through flexible, user-defined and 5 * possibly JIT-ed BPF filters for traffic control as an alternative to 6 * ematches. 7 * 8 * (C) 2013 Daniel Borkmann <dborkman@redhat.com> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <linux/skbuff.h> 18 #include <linux/filter.h> 19 #include <net/rtnetlink.h> 20 #include <net/pkt_cls.h> 21 #include <net/sock.h> 22 23 MODULE_LICENSE("GPL"); 24 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); 25 MODULE_DESCRIPTION("TC BPF based classifier"); 26 27 struct cls_bpf_head { 28 struct list_head plist; 29 u32 hgen; 30 struct rcu_head rcu; 31 }; 32 33 struct cls_bpf_prog { 34 struct bpf_prog *filter; 35 struct sock_filter *bpf_ops; 36 struct tcf_exts exts; 37 struct tcf_result res; 38 struct list_head link; 39 u32 handle; 40 u16 bpf_len; 41 struct tcf_proto *tp; 42 struct rcu_head rcu; 43 }; 44 45 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { 46 [TCA_BPF_CLASSID] = { .type = NLA_U32 }, 47 [TCA_BPF_OPS_LEN] = { .type = NLA_U16 }, 48 [TCA_BPF_OPS] = { .type = NLA_BINARY, 49 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 50 }; 51 52 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, 53 struct tcf_result *res) 54 { 55 struct cls_bpf_head *head = rcu_dereference_bh(tp->root); 56 struct cls_bpf_prog *prog; 57 int ret; 58 59 list_for_each_entry_rcu(prog, &head->plist, link) { 60 int filter_res = BPF_PROG_RUN(prog->filter, skb); 61 62 if (filter_res == 0) 63 continue; 64 65 *res = prog->res; 66 if (filter_res != -1) 67 res->classid = filter_res; 68 69 ret = tcf_exts_exec(skb, &prog->exts, res); 70 if (ret < 0) 71 continue; 72 73 return ret; 74 } 75 76 return -1; 77 } 78 79 static int cls_bpf_init(struct tcf_proto *tp) 80 { 81 struct cls_bpf_head *head; 82 83 head = kzalloc(sizeof(*head), GFP_KERNEL); 84 if (head == NULL) 85 return -ENOBUFS; 86 87 INIT_LIST_HEAD_RCU(&head->plist); 88 rcu_assign_pointer(tp->root, head); 89 90 return 0; 91 } 92 93 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 94 { 95 tcf_exts_destroy(&prog->exts); 96 97 bpf_prog_destroy(prog->filter); 98 99 kfree(prog->bpf_ops); 100 kfree(prog); 101 } 102 103 static void __cls_bpf_delete_prog(struct rcu_head *rcu) 104 { 105 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); 106 107 cls_bpf_delete_prog(prog->tp, prog); 108 } 109 110 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 111 { 112 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg; 113 114 list_del_rcu(&prog->link); 115 tcf_unbind_filter(tp, &prog->res); 116 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 117 return 0; 118 } 119 120 static void cls_bpf_destroy(struct tcf_proto *tp) 121 { 122 struct cls_bpf_head *head = rtnl_dereference(tp->root); 123 struct cls_bpf_prog *prog, *tmp; 124 125 list_for_each_entry_safe(prog, tmp, &head->plist, link) { 126 list_del_rcu(&prog->link); 127 tcf_unbind_filter(tp, &prog->res); 128 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 129 } 130 131 RCU_INIT_POINTER(tp->root, NULL); 132 kfree_rcu(head, rcu); 133 } 134 135 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) 136 { 137 struct cls_bpf_head *head = rtnl_dereference(tp->root); 138 struct cls_bpf_prog *prog; 139 unsigned long ret = 0UL; 140 141 if (head == NULL) 142 return 0UL; 143 144 list_for_each_entry(prog, &head->plist, link) { 145 if (prog->handle == handle) { 146 ret = (unsigned long) prog; 147 break; 148 } 149 } 150 151 return ret; 152 } 153 154 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 155 struct cls_bpf_prog *prog, 156 unsigned long base, struct nlattr **tb, 157 struct nlattr *est, bool ovr) 158 { 159 struct sock_filter *bpf_ops; 160 struct tcf_exts exts; 161 struct sock_fprog_kern tmp; 162 struct bpf_prog *fp; 163 u16 bpf_size, bpf_len; 164 u32 classid; 165 int ret; 166 167 if (!tb[TCA_BPF_OPS_LEN] || !tb[TCA_BPF_OPS] || !tb[TCA_BPF_CLASSID]) 168 return -EINVAL; 169 170 tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); 171 ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr); 172 if (ret < 0) 173 return ret; 174 175 classid = nla_get_u32(tb[TCA_BPF_CLASSID]); 176 bpf_len = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 177 if (bpf_len > BPF_MAXINSNS || bpf_len == 0) { 178 ret = -EINVAL; 179 goto errout; 180 } 181 182 bpf_size = bpf_len * sizeof(*bpf_ops); 183 if (bpf_size != nla_len(tb[TCA_BPF_OPS])) { 184 ret = -EINVAL; 185 goto errout; 186 } 187 188 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 189 if (bpf_ops == NULL) { 190 ret = -ENOMEM; 191 goto errout; 192 } 193 194 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 195 196 tmp.len = bpf_len; 197 tmp.filter = bpf_ops; 198 199 ret = bpf_prog_create(&fp, &tmp); 200 if (ret) 201 goto errout_free; 202 203 prog->bpf_len = bpf_len; 204 prog->bpf_ops = bpf_ops; 205 prog->filter = fp; 206 prog->res.classid = classid; 207 208 tcf_bind_filter(tp, &prog->res, base); 209 tcf_exts_change(tp, &prog->exts, &exts); 210 211 return 0; 212 errout_free: 213 kfree(bpf_ops); 214 errout: 215 tcf_exts_destroy(&exts); 216 return ret; 217 } 218 219 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, 220 struct cls_bpf_head *head) 221 { 222 unsigned int i = 0x80000000; 223 u32 handle; 224 225 do { 226 if (++head->hgen == 0x7FFFFFFF) 227 head->hgen = 1; 228 } while (--i > 0 && cls_bpf_get(tp, head->hgen)); 229 230 if (unlikely(i == 0)) { 231 pr_err("Insufficient number of handles\n"); 232 handle = 0; 233 } else { 234 handle = head->hgen; 235 } 236 237 return handle; 238 } 239 240 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 241 struct tcf_proto *tp, unsigned long base, 242 u32 handle, struct nlattr **tca, 243 unsigned long *arg, bool ovr) 244 { 245 struct cls_bpf_head *head = rtnl_dereference(tp->root); 246 struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; 247 struct nlattr *tb[TCA_BPF_MAX + 1]; 248 struct cls_bpf_prog *prog; 249 int ret; 250 251 if (tca[TCA_OPTIONS] == NULL) 252 return -EINVAL; 253 254 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); 255 if (ret < 0) 256 return ret; 257 258 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 259 if (!prog) 260 return -ENOBUFS; 261 262 tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 263 264 if (oldprog) { 265 if (handle && oldprog->handle != handle) { 266 ret = -EINVAL; 267 goto errout; 268 } 269 } 270 271 if (handle == 0) 272 prog->handle = cls_bpf_grab_new_handle(tp, head); 273 else 274 prog->handle = handle; 275 if (prog->handle == 0) { 276 ret = -EINVAL; 277 goto errout; 278 } 279 280 ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr); 281 if (ret < 0) 282 goto errout; 283 284 if (oldprog) { 285 list_replace_rcu(&prog->link, &oldprog->link); 286 tcf_unbind_filter(tp, &oldprog->res); 287 call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); 288 } else { 289 list_add_rcu(&prog->link, &head->plist); 290 } 291 292 *arg = (unsigned long) prog; 293 return 0; 294 errout: 295 kfree(prog); 296 297 return ret; 298 } 299 300 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 301 struct sk_buff *skb, struct tcmsg *tm) 302 { 303 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; 304 struct nlattr *nest, *nla; 305 306 if (prog == NULL) 307 return skb->len; 308 309 tm->tcm_handle = prog->handle; 310 311 nest = nla_nest_start(skb, TCA_OPTIONS); 312 if (nest == NULL) 313 goto nla_put_failure; 314 315 if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 316 goto nla_put_failure; 317 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_len)) 318 goto nla_put_failure; 319 320 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_len * 321 sizeof(struct sock_filter)); 322 if (nla == NULL) 323 goto nla_put_failure; 324 325 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 326 327 if (tcf_exts_dump(skb, &prog->exts) < 0) 328 goto nla_put_failure; 329 330 nla_nest_end(skb, nest); 331 332 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 333 goto nla_put_failure; 334 335 return skb->len; 336 337 nla_put_failure: 338 nla_nest_cancel(skb, nest); 339 return -1; 340 } 341 342 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 343 { 344 struct cls_bpf_head *head = rtnl_dereference(tp->root); 345 struct cls_bpf_prog *prog; 346 347 list_for_each_entry(prog, &head->plist, link) { 348 if (arg->count < arg->skip) 349 goto skip; 350 if (arg->fn(tp, (unsigned long) prog, arg) < 0) { 351 arg->stop = 1; 352 break; 353 } 354 skip: 355 arg->count++; 356 } 357 } 358 359 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 360 .kind = "bpf", 361 .owner = THIS_MODULE, 362 .classify = cls_bpf_classify, 363 .init = cls_bpf_init, 364 .destroy = cls_bpf_destroy, 365 .get = cls_bpf_get, 366 .change = cls_bpf_change, 367 .delete = cls_bpf_delete, 368 .walk = cls_bpf_walk, 369 .dump = cls_bpf_dump, 370 }; 371 372 static int __init cls_bpf_init_mod(void) 373 { 374 return register_tcf_proto_ops(&cls_bpf_ops); 375 } 376 377 static void __exit cls_bpf_exit_mod(void) 378 { 379 unregister_tcf_proto_ops(&cls_bpf_ops); 380 } 381 382 module_init(cls_bpf_init_mod); 383 module_exit(cls_bpf_exit_mod); 384