1 /* 2 * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 */ 9 10 #include <linux/module.h> 11 #include <linux/init.h> 12 #include <linux/kernel.h> 13 #include <linux/skbuff.h> 14 #include <linux/rtnetlink.h> 15 #include <linux/filter.h> 16 #include <linux/bpf.h> 17 18 #include <net/netlink.h> 19 #include <net/pkt_sched.h> 20 21 #include <linux/tc_act/tc_bpf.h> 22 #include <net/tc_act/tc_bpf.h> 23 24 #define BPF_TAB_MASK 15 25 #define ACT_BPF_NAME_LEN 256 26 27 struct tcf_bpf_cfg { 28 struct bpf_prog *filter; 29 struct sock_filter *bpf_ops; 30 const char *bpf_name; 31 u32 bpf_fd; 32 u16 bpf_num_ops; 33 bool is_ebpf; 34 }; 35 36 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act, 37 struct tcf_result *res) 38 { 39 struct tcf_bpf *prog = act->priv; 40 struct bpf_prog *filter; 41 int action, filter_res; 42 bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS; 43 44 if (unlikely(!skb_mac_header_was_set(skb))) 45 return TC_ACT_UNSPEC; 46 47 tcf_lastuse_update(&prog->tcf_tm); 48 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 49 50 rcu_read_lock(); 51 filter = rcu_dereference(prog->filter); 52 if (at_ingress) { 53 __skb_push(skb, skb->mac_len); 54 filter_res = BPF_PROG_RUN(filter, skb); 55 __skb_pull(skb, skb->mac_len); 56 } else { 57 filter_res = BPF_PROG_RUN(filter, skb); 58 } 59 rcu_read_unlock(); 60 61 /* A BPF program may overwrite the default action opcode. 62 * Similarly as in cls_bpf, if filter_res == -1 we use the 63 * default action specified from tc. 64 * 65 * In case a different well-known TC_ACT opcode has been 66 * returned, it will overwrite the default one. 67 * 68 * For everything else that is unkown, TC_ACT_UNSPEC is 69 * returned. 70 */ 71 switch (filter_res) { 72 case TC_ACT_PIPE: 73 case TC_ACT_RECLASSIFY: 74 case TC_ACT_OK: 75 case TC_ACT_REDIRECT: 76 action = filter_res; 77 break; 78 case TC_ACT_SHOT: 79 action = filter_res; 80 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 81 break; 82 case TC_ACT_UNSPEC: 83 action = prog->tcf_action; 84 break; 85 default: 86 action = TC_ACT_UNSPEC; 87 break; 88 } 89 90 return action; 91 } 92 93 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 94 { 95 return !prog->bpf_ops; 96 } 97 98 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 99 struct sk_buff *skb) 100 { 101 struct nlattr *nla; 102 103 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 104 return -EMSGSIZE; 105 106 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 107 sizeof(struct sock_filter)); 108 if (nla == NULL) 109 return -EMSGSIZE; 110 111 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 112 113 return 0; 114 } 115 116 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 117 struct sk_buff *skb) 118 { 119 if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd)) 120 return -EMSGSIZE; 121 122 if (prog->bpf_name && 123 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 124 return -EMSGSIZE; 125 126 return 0; 127 } 128 129 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act, 130 int bind, int ref) 131 { 132 unsigned char *tp = skb_tail_pointer(skb); 133 struct tcf_bpf *prog = act->priv; 134 struct tc_act_bpf opt = { 135 .index = prog->tcf_index, 136 .refcnt = prog->tcf_refcnt - ref, 137 .bindcnt = prog->tcf_bindcnt - bind, 138 .action = prog->tcf_action, 139 }; 140 struct tcf_t tm; 141 int ret; 142 143 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 144 goto nla_put_failure; 145 146 if (tcf_bpf_is_ebpf(prog)) 147 ret = tcf_bpf_dump_ebpf_info(prog, skb); 148 else 149 ret = tcf_bpf_dump_bpf_info(prog, skb); 150 if (ret) 151 goto nla_put_failure; 152 153 tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install); 154 tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse); 155 tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires); 156 157 if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm)) 158 goto nla_put_failure; 159 160 return skb->len; 161 162 nla_put_failure: 163 nlmsg_trim(skb, tp); 164 return -1; 165 } 166 167 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 168 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 169 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 170 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, .len = ACT_BPF_NAME_LEN }, 171 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 172 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 173 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 174 }; 175 176 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 177 { 178 struct sock_filter *bpf_ops; 179 struct sock_fprog_kern fprog_tmp; 180 struct bpf_prog *fp; 181 u16 bpf_size, bpf_num_ops; 182 int ret; 183 184 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 185 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 186 return -EINVAL; 187 188 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 189 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 190 return -EINVAL; 191 192 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 193 if (bpf_ops == NULL) 194 return -ENOMEM; 195 196 memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size); 197 198 fprog_tmp.len = bpf_num_ops; 199 fprog_tmp.filter = bpf_ops; 200 201 ret = bpf_prog_create(&fp, &fprog_tmp); 202 if (ret < 0) { 203 kfree(bpf_ops); 204 return ret; 205 } 206 207 cfg->bpf_ops = bpf_ops; 208 cfg->bpf_num_ops = bpf_num_ops; 209 cfg->filter = fp; 210 cfg->is_ebpf = false; 211 212 return 0; 213 } 214 215 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 216 { 217 struct bpf_prog *fp; 218 char *name = NULL; 219 u32 bpf_fd; 220 221 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 222 223 fp = bpf_prog_get(bpf_fd); 224 if (IS_ERR(fp)) 225 return PTR_ERR(fp); 226 227 if (fp->type != BPF_PROG_TYPE_SCHED_ACT) { 228 bpf_prog_put(fp); 229 return -EINVAL; 230 } 231 232 if (tb[TCA_ACT_BPF_NAME]) { 233 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]), 234 nla_len(tb[TCA_ACT_BPF_NAME]), 235 GFP_KERNEL); 236 if (!name) { 237 bpf_prog_put(fp); 238 return -ENOMEM; 239 } 240 } 241 242 cfg->bpf_fd = bpf_fd; 243 cfg->bpf_name = name; 244 cfg->filter = fp; 245 cfg->is_ebpf = true; 246 247 return 0; 248 } 249 250 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 251 { 252 if (cfg->is_ebpf) 253 bpf_prog_put(cfg->filter); 254 else 255 bpf_prog_destroy(cfg->filter); 256 257 kfree(cfg->bpf_ops); 258 kfree(cfg->bpf_name); 259 } 260 261 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 262 struct tcf_bpf_cfg *cfg) 263 { 264 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 265 /* updates to prog->filter are prevented, since it's called either 266 * with rtnl lock or during final cleanup in rcu callback 267 */ 268 cfg->filter = rcu_dereference_protected(prog->filter, 1); 269 270 cfg->bpf_ops = prog->bpf_ops; 271 cfg->bpf_name = prog->bpf_name; 272 } 273 274 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 275 struct nlattr *est, struct tc_action *act, 276 int replace, int bind) 277 { 278 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 279 struct tcf_bpf_cfg cfg, old; 280 struct tc_act_bpf *parm; 281 struct tcf_bpf *prog; 282 bool is_bpf, is_ebpf; 283 int ret, res = 0; 284 285 if (!nla) 286 return -EINVAL; 287 288 ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy); 289 if (ret < 0) 290 return ret; 291 292 if (!tb[TCA_ACT_BPF_PARMS]) 293 return -EINVAL; 294 295 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 296 297 if (!tcf_hash_check(parm->index, act, bind)) { 298 ret = tcf_hash_create(parm->index, est, act, 299 sizeof(*prog), bind, true); 300 if (ret < 0) 301 return ret; 302 303 res = ACT_P_CREATED; 304 } else { 305 /* Don't override defaults. */ 306 if (bind) 307 return 0; 308 309 tcf_hash_release(act, bind); 310 if (!replace) 311 return -EEXIST; 312 } 313 314 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 315 is_ebpf = tb[TCA_ACT_BPF_FD]; 316 317 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 318 ret = -EINVAL; 319 goto out; 320 } 321 322 memset(&cfg, 0, sizeof(cfg)); 323 324 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 325 tcf_bpf_init_from_efd(tb, &cfg); 326 if (ret < 0) 327 goto out; 328 329 prog = to_bpf(act); 330 ASSERT_RTNL(); 331 332 if (res != ACT_P_CREATED) 333 tcf_bpf_prog_fill_cfg(prog, &old); 334 335 prog->bpf_ops = cfg.bpf_ops; 336 prog->bpf_name = cfg.bpf_name; 337 338 if (cfg.bpf_num_ops) 339 prog->bpf_num_ops = cfg.bpf_num_ops; 340 if (cfg.bpf_fd) 341 prog->bpf_fd = cfg.bpf_fd; 342 343 prog->tcf_action = parm->action; 344 rcu_assign_pointer(prog->filter, cfg.filter); 345 346 if (res == ACT_P_CREATED) { 347 tcf_hash_insert(act); 348 } else { 349 /* make sure the program being replaced is no longer executing */ 350 synchronize_rcu(); 351 tcf_bpf_cfg_cleanup(&old); 352 } 353 354 return res; 355 out: 356 if (res == ACT_P_CREATED) 357 tcf_hash_cleanup(act, est); 358 359 return ret; 360 } 361 362 static void tcf_bpf_cleanup(struct tc_action *act, int bind) 363 { 364 struct tcf_bpf_cfg tmp; 365 366 tcf_bpf_prog_fill_cfg(act->priv, &tmp); 367 tcf_bpf_cfg_cleanup(&tmp); 368 } 369 370 static struct tc_action_ops act_bpf_ops __read_mostly = { 371 .kind = "bpf", 372 .type = TCA_ACT_BPF, 373 .owner = THIS_MODULE, 374 .act = tcf_bpf, 375 .dump = tcf_bpf_dump, 376 .cleanup = tcf_bpf_cleanup, 377 .init = tcf_bpf_init, 378 }; 379 380 static int __init bpf_init_module(void) 381 { 382 return tcf_register_action(&act_bpf_ops, BPF_TAB_MASK); 383 } 384 385 static void __exit bpf_cleanup_module(void) 386 { 387 tcf_unregister_action(&act_bpf_ops); 388 } 389 390 module_init(bpf_init_module); 391 module_exit(bpf_cleanup_module); 392 393 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 394 MODULE_DESCRIPTION("TC BPF based action"); 395 MODULE_LICENSE("GPL v2"); 396