1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Unstable Conntrack Helpers for XDP and TC-BPF hook 3 * 4 * These are called from the XDP and SCHED_CLS BPF programs. Note that it is 5 * allowed to break compatibility for these functions since the interface they 6 * are exposed through to BPF programs is explicitly unstable. 7 */ 8 9 #include <linux/bpf_verifier.h> 10 #include <linux/bpf.h> 11 #include <linux/btf.h> 12 #include <linux/filter.h> 13 #include <linux/mutex.h> 14 #include <linux/types.h> 15 #include <linux/btf_ids.h> 16 #include <linux/net_namespace.h> 17 #include <net/netfilter/nf_conntrack_bpf.h> 18 #include <net/netfilter/nf_conntrack_core.h> 19 20 /* bpf_ct_opts - Options for CT lookup helpers 21 * 22 * Members: 23 * @netns_id - Specify the network namespace for lookup 24 * Values: 25 * BPF_F_CURRENT_NETNS (-1) 26 * Use namespace associated with ctx (xdp_md, __sk_buff) 27 * [0, S32_MAX] 28 * Network Namespace ID 29 * @error - Out parameter, set for any errors encountered 30 * Values: 31 * -EINVAL - Passed NULL for bpf_tuple pointer 32 * -EINVAL - opts->reserved is not 0 33 * -EINVAL - netns_id is less than -1 34 * -EINVAL - opts__sz isn't NF_BPF_CT_OPTS_SZ (12) 35 * -EPROTO - l4proto isn't one of IPPROTO_TCP or IPPROTO_UDP 36 * -ENONET - No network namespace found for netns_id 37 * -ENOENT - Conntrack lookup could not find entry for tuple 38 * -EAFNOSUPPORT - tuple__sz isn't one of sizeof(tuple->ipv4) 39 * or sizeof(tuple->ipv6) 40 * @l4proto - Layer 4 protocol 41 * Values: 42 * IPPROTO_TCP, IPPROTO_UDP 43 * @dir: - connection tracking tuple direction. 44 * @reserved - Reserved member, will be reused for more options in future 45 * Values: 46 * 0 47 */ 48 struct bpf_ct_opts { 49 s32 netns_id; 50 s32 error; 51 u8 l4proto; 52 u8 dir; 53 u8 reserved[2]; 54 }; 55 56 enum { 57 NF_BPF_CT_OPTS_SZ = 12, 58 }; 59 60 static int bpf_nf_ct_tuple_parse(struct bpf_sock_tuple *bpf_tuple, 61 u32 tuple_len, u8 protonum, u8 dir, 62 struct nf_conntrack_tuple *tuple) 63 { 64 union nf_inet_addr *src = dir ? &tuple->dst.u3 : &tuple->src.u3; 65 union nf_inet_addr *dst = dir ? &tuple->src.u3 : &tuple->dst.u3; 66 union nf_conntrack_man_proto *sport = dir ? (void *)&tuple->dst.u 67 : &tuple->src.u; 68 union nf_conntrack_man_proto *dport = dir ? &tuple->src.u 69 : (void *)&tuple->dst.u; 70 71 if (unlikely(protonum != IPPROTO_TCP && protonum != IPPROTO_UDP)) 72 return -EPROTO; 73 74 memset(tuple, 0, sizeof(*tuple)); 75 76 switch (tuple_len) { 77 case sizeof(bpf_tuple->ipv4): 78 tuple->src.l3num = AF_INET; 79 src->ip = bpf_tuple->ipv4.saddr; 80 sport->tcp.port = bpf_tuple->ipv4.sport; 81 dst->ip = bpf_tuple->ipv4.daddr; 82 dport->tcp.port = bpf_tuple->ipv4.dport; 83 break; 84 case sizeof(bpf_tuple->ipv6): 85 tuple->src.l3num = AF_INET6; 86 memcpy(src->ip6, bpf_tuple->ipv6.saddr, sizeof(bpf_tuple->ipv6.saddr)); 87 sport->tcp.port = bpf_tuple->ipv6.sport; 88 memcpy(dst->ip6, bpf_tuple->ipv6.daddr, sizeof(bpf_tuple->ipv6.daddr)); 89 dport->tcp.port = bpf_tuple->ipv6.dport; 90 break; 91 default: 92 return -EAFNOSUPPORT; 93 } 94 tuple->dst.protonum = protonum; 95 tuple->dst.dir = dir; 96 97 return 0; 98 } 99 100 static struct nf_conn * 101 __bpf_nf_ct_alloc_entry(struct net *net, struct bpf_sock_tuple *bpf_tuple, 102 u32 tuple_len, struct bpf_ct_opts *opts, u32 opts_len, 103 u32 timeout) 104 { 105 struct nf_conntrack_tuple otuple, rtuple; 106 struct nf_conn *ct; 107 int err; 108 109 if (!opts || !bpf_tuple || opts->reserved[0] || opts->reserved[1] || 110 opts_len != NF_BPF_CT_OPTS_SZ) 111 return ERR_PTR(-EINVAL); 112 113 if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) 114 return ERR_PTR(-EINVAL); 115 116 err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, 117 IP_CT_DIR_ORIGINAL, &otuple); 118 if (err < 0) 119 return ERR_PTR(err); 120 121 err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, 122 IP_CT_DIR_REPLY, &rtuple); 123 if (err < 0) 124 return ERR_PTR(err); 125 126 if (opts->netns_id >= 0) { 127 net = get_net_ns_by_id(net, opts->netns_id); 128 if (unlikely(!net)) 129 return ERR_PTR(-ENONET); 130 } 131 132 ct = nf_conntrack_alloc(net, &nf_ct_zone_dflt, &otuple, &rtuple, 133 GFP_ATOMIC); 134 if (IS_ERR(ct)) 135 goto out; 136 137 memset(&ct->proto, 0, sizeof(ct->proto)); 138 __nf_ct_set_timeout(ct, timeout * HZ); 139 140 out: 141 if (opts->netns_id >= 0) 142 put_net(net); 143 144 return ct; 145 } 146 147 static struct nf_conn *__bpf_nf_ct_lookup(struct net *net, 148 struct bpf_sock_tuple *bpf_tuple, 149 u32 tuple_len, struct bpf_ct_opts *opts, 150 u32 opts_len) 151 { 152 struct nf_conntrack_tuple_hash *hash; 153 struct nf_conntrack_tuple tuple; 154 struct nf_conn *ct; 155 int err; 156 157 if (!opts || !bpf_tuple || opts->reserved[0] || opts->reserved[1] || 158 opts_len != NF_BPF_CT_OPTS_SZ) 159 return ERR_PTR(-EINVAL); 160 if (unlikely(opts->l4proto != IPPROTO_TCP && opts->l4proto != IPPROTO_UDP)) 161 return ERR_PTR(-EPROTO); 162 if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) 163 return ERR_PTR(-EINVAL); 164 165 err = bpf_nf_ct_tuple_parse(bpf_tuple, tuple_len, opts->l4proto, 166 IP_CT_DIR_ORIGINAL, &tuple); 167 if (err < 0) 168 return ERR_PTR(err); 169 170 if (opts->netns_id >= 0) { 171 net = get_net_ns_by_id(net, opts->netns_id); 172 if (unlikely(!net)) 173 return ERR_PTR(-ENONET); 174 } 175 176 hash = nf_conntrack_find_get(net, &nf_ct_zone_dflt, &tuple); 177 if (opts->netns_id >= 0) 178 put_net(net); 179 if (!hash) 180 return ERR_PTR(-ENOENT); 181 182 ct = nf_ct_tuplehash_to_ctrack(hash); 183 opts->dir = NF_CT_DIRECTION(hash); 184 185 return ct; 186 } 187 188 BTF_ID_LIST(btf_nf_conn_ids) 189 BTF_ID(struct, nf_conn) 190 BTF_ID(struct, nf_conn___init) 191 192 /* Check writes into `struct nf_conn` */ 193 static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, 194 const struct btf *btf, 195 const struct btf_type *t, int off, 196 int size, enum bpf_access_type atype, 197 u32 *next_btf_id, 198 enum bpf_type_flag *flag) 199 { 200 const struct btf_type *ncit; 201 const struct btf_type *nct; 202 size_t end; 203 204 ncit = btf_type_by_id(btf, btf_nf_conn_ids[1]); 205 nct = btf_type_by_id(btf, btf_nf_conn_ids[0]); 206 207 if (t != nct && t != ncit) { 208 bpf_log(log, "only read is supported\n"); 209 return -EACCES; 210 } 211 212 /* `struct nf_conn` and `struct nf_conn___init` have the same layout 213 * so we are safe to simply merge offset checks here 214 */ 215 switch (off) { 216 #if defined(CONFIG_NF_CONNTRACK_MARK) 217 case offsetof(struct nf_conn, mark): 218 end = offsetofend(struct nf_conn, mark); 219 break; 220 #endif 221 default: 222 bpf_log(log, "no write support to nf_conn at off %d\n", off); 223 return -EACCES; 224 } 225 226 if (off + size > end) { 227 bpf_log(log, 228 "write access at off %d with size %d beyond the member of nf_conn ended at %zu\n", 229 off, size, end); 230 return -EACCES; 231 } 232 233 return 0; 234 } 235 236 __diag_push(); 237 __diag_ignore_all("-Wmissing-prototypes", 238 "Global functions as their definitions will be in nf_conntrack BTF"); 239 240 /* bpf_xdp_ct_alloc - Allocate a new CT entry 241 * 242 * Parameters: 243 * @xdp_ctx - Pointer to ctx (xdp_md) in XDP program 244 * Cannot be NULL 245 * @bpf_tuple - Pointer to memory representing the tuple to look up 246 * Cannot be NULL 247 * @tuple__sz - Length of the tuple structure 248 * Must be one of sizeof(bpf_tuple->ipv4) or 249 * sizeof(bpf_tuple->ipv6) 250 * @opts - Additional options for allocation (documented above) 251 * Cannot be NULL 252 * @opts__sz - Length of the bpf_ct_opts structure 253 * Must be NF_BPF_CT_OPTS_SZ (12) 254 */ 255 struct nf_conn___init * 256 bpf_xdp_ct_alloc(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple, 257 u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz) 258 { 259 struct xdp_buff *ctx = (struct xdp_buff *)xdp_ctx; 260 struct nf_conn *nfct; 261 262 nfct = __bpf_nf_ct_alloc_entry(dev_net(ctx->rxq->dev), bpf_tuple, tuple__sz, 263 opts, opts__sz, 10); 264 if (IS_ERR(nfct)) { 265 if (opts) 266 opts->error = PTR_ERR(nfct); 267 return NULL; 268 } 269 270 return (struct nf_conn___init *)nfct; 271 } 272 273 /* bpf_xdp_ct_lookup - Lookup CT entry for the given tuple, and acquire a 274 * reference to it 275 * 276 * Parameters: 277 * @xdp_ctx - Pointer to ctx (xdp_md) in XDP program 278 * Cannot be NULL 279 * @bpf_tuple - Pointer to memory representing the tuple to look up 280 * Cannot be NULL 281 * @tuple__sz - Length of the tuple structure 282 * Must be one of sizeof(bpf_tuple->ipv4) or 283 * sizeof(bpf_tuple->ipv6) 284 * @opts - Additional options for lookup (documented above) 285 * Cannot be NULL 286 * @opts__sz - Length of the bpf_ct_opts structure 287 * Must be NF_BPF_CT_OPTS_SZ (12) 288 */ 289 struct nf_conn * 290 bpf_xdp_ct_lookup(struct xdp_md *xdp_ctx, struct bpf_sock_tuple *bpf_tuple, 291 u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz) 292 { 293 struct xdp_buff *ctx = (struct xdp_buff *)xdp_ctx; 294 struct net *caller_net; 295 struct nf_conn *nfct; 296 297 caller_net = dev_net(ctx->rxq->dev); 298 nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz); 299 if (IS_ERR(nfct)) { 300 if (opts) 301 opts->error = PTR_ERR(nfct); 302 return NULL; 303 } 304 return nfct; 305 } 306 307 /* bpf_skb_ct_alloc - Allocate a new CT entry 308 * 309 * Parameters: 310 * @skb_ctx - Pointer to ctx (__sk_buff) in TC program 311 * Cannot be NULL 312 * @bpf_tuple - Pointer to memory representing the tuple to look up 313 * Cannot be NULL 314 * @tuple__sz - Length of the tuple structure 315 * Must be one of sizeof(bpf_tuple->ipv4) or 316 * sizeof(bpf_tuple->ipv6) 317 * @opts - Additional options for allocation (documented above) 318 * Cannot be NULL 319 * @opts__sz - Length of the bpf_ct_opts structure 320 * Must be NF_BPF_CT_OPTS_SZ (12) 321 */ 322 struct nf_conn___init * 323 bpf_skb_ct_alloc(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple, 324 u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz) 325 { 326 struct sk_buff *skb = (struct sk_buff *)skb_ctx; 327 struct nf_conn *nfct; 328 struct net *net; 329 330 net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk); 331 nfct = __bpf_nf_ct_alloc_entry(net, bpf_tuple, tuple__sz, opts, opts__sz, 10); 332 if (IS_ERR(nfct)) { 333 if (opts) 334 opts->error = PTR_ERR(nfct); 335 return NULL; 336 } 337 338 return (struct nf_conn___init *)nfct; 339 } 340 341 /* bpf_skb_ct_lookup - Lookup CT entry for the given tuple, and acquire a 342 * reference to it 343 * 344 * Parameters: 345 * @skb_ctx - Pointer to ctx (__sk_buff) in TC program 346 * Cannot be NULL 347 * @bpf_tuple - Pointer to memory representing the tuple to look up 348 * Cannot be NULL 349 * @tuple__sz - Length of the tuple structure 350 * Must be one of sizeof(bpf_tuple->ipv4) or 351 * sizeof(bpf_tuple->ipv6) 352 * @opts - Additional options for lookup (documented above) 353 * Cannot be NULL 354 * @opts__sz - Length of the bpf_ct_opts structure 355 * Must be NF_BPF_CT_OPTS_SZ (12) 356 */ 357 struct nf_conn * 358 bpf_skb_ct_lookup(struct __sk_buff *skb_ctx, struct bpf_sock_tuple *bpf_tuple, 359 u32 tuple__sz, struct bpf_ct_opts *opts, u32 opts__sz) 360 { 361 struct sk_buff *skb = (struct sk_buff *)skb_ctx; 362 struct net *caller_net; 363 struct nf_conn *nfct; 364 365 caller_net = skb->dev ? dev_net(skb->dev) : sock_net(skb->sk); 366 nfct = __bpf_nf_ct_lookup(caller_net, bpf_tuple, tuple__sz, opts, opts__sz); 367 if (IS_ERR(nfct)) { 368 if (opts) 369 opts->error = PTR_ERR(nfct); 370 return NULL; 371 } 372 return nfct; 373 } 374 375 /* bpf_ct_insert_entry - Add the provided entry into a CT map 376 * 377 * This must be invoked for referenced PTR_TO_BTF_ID. 378 * 379 * @nfct - Pointer to referenced nf_conn___init object, obtained 380 * using bpf_xdp_ct_alloc or bpf_skb_ct_alloc. 381 */ 382 struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i) 383 { 384 struct nf_conn *nfct = (struct nf_conn *)nfct_i; 385 int err; 386 387 nfct->status |= IPS_CONFIRMED; 388 err = nf_conntrack_hash_check_insert(nfct); 389 if (err < 0) { 390 nf_conntrack_free(nfct); 391 return NULL; 392 } 393 return nfct; 394 } 395 396 /* bpf_ct_release - Release acquired nf_conn object 397 * 398 * This must be invoked for referenced PTR_TO_BTF_ID, and the verifier rejects 399 * the program if any references remain in the program in all of the explored 400 * states. 401 * 402 * Parameters: 403 * @nf_conn - Pointer to referenced nf_conn object, obtained using 404 * bpf_xdp_ct_lookup or bpf_skb_ct_lookup. 405 */ 406 void bpf_ct_release(struct nf_conn *nfct) 407 { 408 if (!nfct) 409 return; 410 nf_ct_put(nfct); 411 } 412 413 /* bpf_ct_set_timeout - Set timeout of allocated nf_conn 414 * 415 * Sets the default timeout of newly allocated nf_conn before insertion. 416 * This helper must be invoked for refcounted pointer to nf_conn___init. 417 * 418 * Parameters: 419 * @nfct - Pointer to referenced nf_conn object, obtained using 420 * bpf_xdp_ct_alloc or bpf_skb_ct_alloc. 421 * @timeout - Timeout in msecs. 422 */ 423 void bpf_ct_set_timeout(struct nf_conn___init *nfct, u32 timeout) 424 { 425 __nf_ct_set_timeout((struct nf_conn *)nfct, msecs_to_jiffies(timeout)); 426 } 427 428 /* bpf_ct_change_timeout - Change timeout of inserted nf_conn 429 * 430 * Change timeout associated of the inserted or looked up nf_conn. 431 * This helper must be invoked for refcounted pointer to nf_conn. 432 * 433 * Parameters: 434 * @nfct - Pointer to referenced nf_conn object, obtained using 435 * bpf_ct_insert_entry, bpf_xdp_ct_lookup, or bpf_skb_ct_lookup. 436 * @timeout - New timeout in msecs. 437 */ 438 int bpf_ct_change_timeout(struct nf_conn *nfct, u32 timeout) 439 { 440 return __nf_ct_change_timeout(nfct, msecs_to_jiffies(timeout)); 441 } 442 443 /* bpf_ct_set_status - Set status field of allocated nf_conn 444 * 445 * Set the status field of the newly allocated nf_conn before insertion. 446 * This must be invoked for referenced PTR_TO_BTF_ID to nf_conn___init. 447 * 448 * Parameters: 449 * @nfct - Pointer to referenced nf_conn object, obtained using 450 * bpf_xdp_ct_alloc or bpf_skb_ct_alloc. 451 * @status - New status value. 452 */ 453 int bpf_ct_set_status(const struct nf_conn___init *nfct, u32 status) 454 { 455 return nf_ct_change_status_common((struct nf_conn *)nfct, status); 456 } 457 458 /* bpf_ct_change_status - Change status of inserted nf_conn 459 * 460 * Change the status field of the provided connection tracking entry. 461 * This must be invoked for referenced PTR_TO_BTF_ID to nf_conn. 462 * 463 * Parameters: 464 * @nfct - Pointer to referenced nf_conn object, obtained using 465 * bpf_ct_insert_entry, bpf_xdp_ct_lookup or bpf_skb_ct_lookup. 466 * @status - New status value. 467 */ 468 int bpf_ct_change_status(struct nf_conn *nfct, u32 status) 469 { 470 return nf_ct_change_status_common(nfct, status); 471 } 472 473 __diag_pop() 474 475 BTF_SET8_START(nf_ct_kfunc_set) 476 BTF_ID_FLAGS(func, bpf_xdp_ct_alloc, KF_ACQUIRE | KF_RET_NULL) 477 BTF_ID_FLAGS(func, bpf_xdp_ct_lookup, KF_ACQUIRE | KF_RET_NULL) 478 BTF_ID_FLAGS(func, bpf_skb_ct_alloc, KF_ACQUIRE | KF_RET_NULL) 479 BTF_ID_FLAGS(func, bpf_skb_ct_lookup, KF_ACQUIRE | KF_RET_NULL) 480 BTF_ID_FLAGS(func, bpf_ct_insert_entry, KF_ACQUIRE | KF_RET_NULL | KF_RELEASE) 481 BTF_ID_FLAGS(func, bpf_ct_release, KF_RELEASE) 482 BTF_ID_FLAGS(func, bpf_ct_set_timeout, KF_TRUSTED_ARGS) 483 BTF_ID_FLAGS(func, bpf_ct_change_timeout, KF_TRUSTED_ARGS) 484 BTF_ID_FLAGS(func, bpf_ct_set_status, KF_TRUSTED_ARGS) 485 BTF_ID_FLAGS(func, bpf_ct_change_status, KF_TRUSTED_ARGS) 486 BTF_SET8_END(nf_ct_kfunc_set) 487 488 static const struct btf_kfunc_id_set nf_conntrack_kfunc_set = { 489 .owner = THIS_MODULE, 490 .set = &nf_ct_kfunc_set, 491 }; 492 493 int register_nf_conntrack_bpf(void) 494 { 495 int ret; 496 497 ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &nf_conntrack_kfunc_set); 498 ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &nf_conntrack_kfunc_set); 499 if (!ret) { 500 mutex_lock(&nf_conn_btf_access_lock); 501 nfct_btf_struct_access = _nf_conntrack_btf_struct_access; 502 mutex_unlock(&nf_conn_btf_access_lock); 503 } 504 505 return ret; 506 } 507 508 void cleanup_nf_conntrack_bpf(void) 509 { 510 mutex_lock(&nf_conn_btf_access_lock); 511 nfct_btf_struct_access = NULL; 512 mutex_unlock(&nf_conn_btf_access_lock); 513 } 514