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 }; 31 32 struct cls_bpf_prog { 33 struct sk_filter *filter; 34 struct sock_filter *bpf_ops; 35 struct tcf_exts exts; 36 struct tcf_result res; 37 struct list_head link; 38 u32 handle; 39 u16 bpf_len; 40 }; 41 42 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { 43 [TCA_BPF_CLASSID] = { .type = NLA_U32 }, 44 [TCA_BPF_OPS_LEN] = { .type = NLA_U16 }, 45 [TCA_BPF_OPS] = { .type = NLA_BINARY, 46 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 47 }; 48 49 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, 50 struct tcf_result *res) 51 { 52 struct cls_bpf_head *head = tp->root; 53 struct cls_bpf_prog *prog; 54 int ret; 55 56 list_for_each_entry(prog, &head->plist, link) { 57 int filter_res = SK_RUN_FILTER(prog->filter, skb); 58 59 if (filter_res == 0) 60 continue; 61 62 *res = prog->res; 63 if (filter_res != -1) 64 res->classid = filter_res; 65 66 ret = tcf_exts_exec(skb, &prog->exts, res); 67 if (ret < 0) 68 continue; 69 70 return ret; 71 } 72 73 return -1; 74 } 75 76 static int cls_bpf_init(struct tcf_proto *tp) 77 { 78 struct cls_bpf_head *head; 79 80 head = kzalloc(sizeof(*head), GFP_KERNEL); 81 if (head == NULL) 82 return -ENOBUFS; 83 84 INIT_LIST_HEAD(&head->plist); 85 tp->root = head; 86 87 return 0; 88 } 89 90 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 91 { 92 tcf_unbind_filter(tp, &prog->res); 93 tcf_exts_destroy(tp, &prog->exts); 94 95 sk_unattached_filter_destroy(prog->filter); 96 97 kfree(prog->bpf_ops); 98 kfree(prog); 99 } 100 101 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 102 { 103 struct cls_bpf_head *head = tp->root; 104 struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg; 105 106 list_for_each_entry(prog, &head->plist, link) { 107 if (prog == todel) { 108 tcf_tree_lock(tp); 109 list_del(&prog->link); 110 tcf_tree_unlock(tp); 111 112 cls_bpf_delete_prog(tp, prog); 113 return 0; 114 } 115 } 116 117 return -ENOENT; 118 } 119 120 static void cls_bpf_destroy(struct tcf_proto *tp) 121 { 122 struct cls_bpf_head *head = tp->root; 123 struct cls_bpf_prog *prog, *tmp; 124 125 list_for_each_entry_safe(prog, tmp, &head->plist, link) { 126 list_del(&prog->link); 127 cls_bpf_delete_prog(tp, prog); 128 } 129 130 kfree(head); 131 } 132 133 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) 134 { 135 struct cls_bpf_head *head = tp->root; 136 struct cls_bpf_prog *prog; 137 unsigned long ret = 0UL; 138 139 if (head == NULL) 140 return 0UL; 141 142 list_for_each_entry(prog, &head->plist, link) { 143 if (prog->handle == handle) { 144 ret = (unsigned long) prog; 145 break; 146 } 147 } 148 149 return ret; 150 } 151 152 static void cls_bpf_put(struct tcf_proto *tp, unsigned long f) 153 { 154 } 155 156 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 157 struct cls_bpf_prog *prog, 158 unsigned long base, struct nlattr **tb, 159 struct nlattr *est) 160 { 161 struct sock_filter *bpf_ops, *bpf_old; 162 struct tcf_exts exts; 163 struct sock_fprog tmp; 164 struct sk_filter *fp, *fp_old; 165 u16 bpf_size, bpf_len; 166 u32 classid; 167 int ret; 168 169 if (!tb[TCA_BPF_OPS_LEN] || !tb[TCA_BPF_OPS] || !tb[TCA_BPF_CLASSID]) 170 return -EINVAL; 171 172 tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); 173 ret = tcf_exts_validate(net, tp, tb, est, &exts); 174 if (ret < 0) 175 return ret; 176 177 classid = nla_get_u32(tb[TCA_BPF_CLASSID]); 178 bpf_len = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 179 if (bpf_len > BPF_MAXINSNS || bpf_len == 0) { 180 ret = -EINVAL; 181 goto errout; 182 } 183 184 bpf_size = bpf_len * sizeof(*bpf_ops); 185 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 186 if (bpf_ops == NULL) { 187 ret = -ENOMEM; 188 goto errout; 189 } 190 191 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 192 193 tmp.len = bpf_len; 194 tmp.filter = (struct sock_filter __user *) bpf_ops; 195 196 ret = sk_unattached_filter_create(&fp, &tmp); 197 if (ret) 198 goto errout_free; 199 200 tcf_tree_lock(tp); 201 fp_old = prog->filter; 202 bpf_old = prog->bpf_ops; 203 204 prog->bpf_len = bpf_len; 205 prog->bpf_ops = bpf_ops; 206 prog->filter = fp; 207 prog->res.classid = classid; 208 tcf_tree_unlock(tp); 209 210 tcf_bind_filter(tp, &prog->res, base); 211 tcf_exts_change(tp, &prog->exts, &exts); 212 213 if (fp_old) 214 sk_unattached_filter_destroy(fp_old); 215 if (bpf_old) 216 kfree(bpf_old); 217 218 return 0; 219 220 errout_free: 221 kfree(bpf_ops); 222 errout: 223 tcf_exts_destroy(tp, &exts); 224 return ret; 225 } 226 227 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, 228 struct cls_bpf_head *head) 229 { 230 unsigned int i = 0x80000000; 231 232 do { 233 if (++head->hgen == 0x7FFFFFFF) 234 head->hgen = 1; 235 } while (--i > 0 && cls_bpf_get(tp, head->hgen)); 236 if (i == 0) 237 pr_err("Insufficient number of handles\n"); 238 239 return i; 240 } 241 242 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 243 struct tcf_proto *tp, unsigned long base, 244 u32 handle, struct nlattr **tca, 245 unsigned long *arg) 246 { 247 struct cls_bpf_head *head = tp->root; 248 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg; 249 struct nlattr *tb[TCA_BPF_MAX + 1]; 250 int ret; 251 252 if (tca[TCA_OPTIONS] == NULL) 253 return -EINVAL; 254 255 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); 256 if (ret < 0) 257 return ret; 258 259 if (prog != NULL) { 260 if (handle && prog->handle != handle) 261 return -EINVAL; 262 return cls_bpf_modify_existing(net, tp, prog, base, tb, 263 tca[TCA_RATE]); 264 } 265 266 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 267 if (prog == NULL) 268 return -ENOBUFS; 269 270 tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 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]); 281 if (ret < 0) 282 goto errout; 283 284 tcf_tree_lock(tp); 285 list_add(&prog->link, &head->plist); 286 tcf_tree_unlock(tp); 287 288 *arg = (unsigned long) prog; 289 290 return 0; 291 errout: 292 if (*arg == 0UL && prog) 293 kfree(prog); 294 295 return ret; 296 } 297 298 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 299 struct sk_buff *skb, struct tcmsg *tm) 300 { 301 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; 302 struct nlattr *nest, *nla; 303 304 if (prog == NULL) 305 return skb->len; 306 307 tm->tcm_handle = prog->handle; 308 309 nest = nla_nest_start(skb, TCA_OPTIONS); 310 if (nest == NULL) 311 goto nla_put_failure; 312 313 if (nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 314 goto nla_put_failure; 315 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_len)) 316 goto nla_put_failure; 317 318 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_len * 319 sizeof(struct sock_filter)); 320 if (nla == NULL) 321 goto nla_put_failure; 322 323 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 324 325 if (tcf_exts_dump(skb, &prog->exts) < 0) 326 goto nla_put_failure; 327 328 nla_nest_end(skb, nest); 329 330 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 331 goto nla_put_failure; 332 333 return skb->len; 334 335 nla_put_failure: 336 nla_nest_cancel(skb, nest); 337 return -1; 338 } 339 340 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 341 { 342 struct cls_bpf_head *head = tp->root; 343 struct cls_bpf_prog *prog; 344 345 list_for_each_entry(prog, &head->plist, link) { 346 if (arg->count < arg->skip) 347 goto skip; 348 if (arg->fn(tp, (unsigned long) prog, arg) < 0) { 349 arg->stop = 1; 350 break; 351 } 352 skip: 353 arg->count++; 354 } 355 } 356 357 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 358 .kind = "bpf", 359 .owner = THIS_MODULE, 360 .classify = cls_bpf_classify, 361 .init = cls_bpf_init, 362 .destroy = cls_bpf_destroy, 363 .get = cls_bpf_get, 364 .put = cls_bpf_put, 365 .change = cls_bpf_change, 366 .delete = cls_bpf_delete, 367 .walk = cls_bpf_walk, 368 .dump = cls_bpf_dump, 369 }; 370 371 static int __init cls_bpf_init_mod(void) 372 { 373 return register_tcf_proto_ops(&cls_bpf_ops); 374 } 375 376 static void __exit cls_bpf_exit_mod(void) 377 { 378 unregister_tcf_proto_ops(&cls_bpf_ops); 379 } 380 381 module_init(cls_bpf_init_mod); 382 module_exit(cls_bpf_exit_mod); 383