1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* SCTP kernel implementation 3 * Copyright (c) 1999-2000 Cisco, Inc. 4 * Copyright (c) 1999-2001 Motorola, Inc. 5 * Copyright (c) 2001-2002 International Business Machines, Corp. 6 * Copyright (c) 2001 Intel Corp. 7 * Copyright (c) 2001 Nokia, Inc. 8 * Copyright (c) 2001 La Monte H.P. Yarroll 9 * 10 * This file is part of the SCTP kernel implementation 11 * 12 * This abstraction represents an SCTP endpoint. 13 * 14 * Please send any bug reports or fixes you make to the 15 * email address(es): 16 * lksctp developers <linux-sctp@vger.kernel.org> 17 * 18 * Written or modified by: 19 * La Monte H.P. Yarroll <piggy@acm.org> 20 * Karl Knutson <karl@athena.chicago.il.us> 21 * Jon Grimm <jgrimm@austin.ibm.com> 22 * Daisy Chang <daisyc@us.ibm.com> 23 * Dajiang Zhang <dajiang.zhang@nokia.com> 24 */ 25 26 #include <linux/types.h> 27 #include <linux/slab.h> 28 #include <linux/in.h> 29 #include <linux/random.h> /* get_random_bytes() */ 30 #include <net/sock.h> 31 #include <net/ipv6.h> 32 #include <net/sctp/sctp.h> 33 #include <net/sctp/sm.h> 34 35 /* Forward declarations for internal helpers. */ 36 static void sctp_endpoint_bh_rcv(struct work_struct *work); 37 38 static void gen_cookie_auth_key(struct hmac_sha256_key *key) 39 { 40 u8 raw_key[SCTP_COOKIE_KEY_SIZE]; 41 42 get_random_bytes(raw_key, sizeof(raw_key)); 43 hmac_sha256_preparekey(key, raw_key, sizeof(raw_key)); 44 memzero_explicit(raw_key, sizeof(raw_key)); 45 } 46 47 /* 48 * Initialize the base fields of the endpoint structure. 49 */ 50 static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep, 51 struct sock *sk, 52 gfp_t gfp) 53 { 54 struct net *net = sock_net(sk); 55 struct sctp_shared_key *null_key; 56 57 ep->asconf_enable = net->sctp.addip_enable; 58 ep->auth_enable = net->sctp.auth_enable; 59 if (ep->auth_enable) { 60 if (sctp_auth_init(ep, gfp)) 61 goto nomem; 62 if (ep->asconf_enable) { 63 sctp_auth_ep_add_chunkid(ep, SCTP_CID_ASCONF); 64 sctp_auth_ep_add_chunkid(ep, SCTP_CID_ASCONF_ACK); 65 } 66 } 67 68 /* Initialize the base structure. */ 69 /* What type of endpoint are we? */ 70 ep->base.type = SCTP_EP_TYPE_SOCKET; 71 72 /* Initialize the basic object fields. */ 73 refcount_set(&ep->base.refcnt, 1); 74 ep->base.dead = false; 75 76 /* Create an input queue. */ 77 sctp_inq_init(&ep->base.inqueue); 78 79 /* Set its top-half handler */ 80 sctp_inq_set_th_handler(&ep->base.inqueue, sctp_endpoint_bh_rcv); 81 82 /* Initialize the bind addr area */ 83 sctp_bind_addr_init(&ep->base.bind_addr, 0); 84 85 /* Create the lists of associations. */ 86 INIT_LIST_HEAD(&ep->asocs); 87 88 /* Use SCTP specific send buffer space queues. */ 89 ep->sndbuf_policy = net->sctp.sndbuf_policy; 90 91 sk->sk_data_ready = sctp_data_ready; 92 sk->sk_write_space = sctp_write_space; 93 sock_set_flag(sk, SOCK_USE_WRITE_QUEUE); 94 95 /* Get the receive buffer policy for this endpoint */ 96 ep->rcvbuf_policy = net->sctp.rcvbuf_policy; 97 98 /* Generate the cookie authentication key. */ 99 gen_cookie_auth_key(&ep->cookie_auth_key); 100 101 /* SCTP-AUTH extensions*/ 102 INIT_LIST_HEAD(&ep->endpoint_shared_keys); 103 null_key = sctp_auth_shkey_create(0, gfp); 104 if (!null_key) 105 goto nomem_shkey; 106 107 list_add(&null_key->key_list, &ep->endpoint_shared_keys); 108 109 /* Add the null key to the endpoint shared keys list and 110 * set the hmcas and chunks pointers. 111 */ 112 ep->prsctp_enable = net->sctp.prsctp_enable; 113 ep->reconf_enable = net->sctp.reconf_enable; 114 ep->ecn_enable = net->sctp.ecn_enable; 115 116 /* Remember who we are attached to. */ 117 ep->base.sk = sk; 118 ep->base.net = sock_net(sk); 119 sock_hold(ep->base.sk); 120 121 return ep; 122 123 nomem_shkey: 124 sctp_auth_free(ep); 125 nomem: 126 return NULL; 127 128 } 129 130 /* Create a sctp_endpoint with all that boring stuff initialized. 131 * Returns NULL if there isn't enough memory. 132 */ 133 struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp) 134 { 135 struct sctp_endpoint *ep; 136 137 /* Build a local endpoint. */ 138 ep = kzalloc(sizeof(*ep), gfp); 139 if (!ep) 140 goto fail; 141 142 if (!sctp_endpoint_init(ep, sk, gfp)) 143 goto fail_init; 144 145 SCTP_DBG_OBJCNT_INC(ep); 146 return ep; 147 148 fail_init: 149 kfree(ep); 150 fail: 151 return NULL; 152 } 153 154 /* Add an association to an endpoint. */ 155 void sctp_endpoint_add_asoc(struct sctp_endpoint *ep, 156 struct sctp_association *asoc) 157 { 158 struct sock *sk = ep->base.sk; 159 160 /* If this is a temporary association, don't bother 161 * since we'll be removing it shortly and don't 162 * want anyone to find it anyway. 163 */ 164 if (asoc->temp) 165 return; 166 167 /* Now just add it to our list of asocs */ 168 list_add_tail(&asoc->asocs, &ep->asocs); 169 170 /* Increment the backlog value for a TCP-style listening socket. */ 171 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING)) 172 sk_acceptq_added(sk); 173 } 174 175 /* Free the endpoint structure. Delay cleanup until 176 * all users have released their reference count on this structure. 177 */ 178 void sctp_endpoint_free(struct sctp_endpoint *ep) 179 { 180 ep->base.dead = true; 181 182 inet_sk_set_state(ep->base.sk, SCTP_SS_CLOSED); 183 184 /* Unlink this endpoint, so we can't find it again! */ 185 sctp_unhash_endpoint(ep); 186 187 sctp_endpoint_put(ep); 188 } 189 190 /* Final destructor for endpoint. */ 191 static void sctp_endpoint_destroy_rcu(struct rcu_head *head) 192 { 193 struct sctp_endpoint *ep = container_of(head, struct sctp_endpoint, rcu); 194 struct sock *sk = ep->base.sk; 195 196 sctp_sk(sk)->ep = NULL; 197 sock_put(sk); 198 199 kfree(ep); 200 SCTP_DBG_OBJCNT_DEC(ep); 201 } 202 203 static void sctp_endpoint_destroy(struct sctp_endpoint *ep) 204 { 205 struct sock *sk; 206 207 if (unlikely(!ep->base.dead)) { 208 WARN(1, "Attempt to destroy undead endpoint %p!\n", ep); 209 return; 210 } 211 212 /* SCTP-AUTH: Free up AUTH releated data such as shared keys 213 * chunks and hmacs arrays that were allocated 214 */ 215 sctp_auth_destroy_keys(&ep->endpoint_shared_keys); 216 sctp_auth_free(ep); 217 218 /* Cleanup. */ 219 sctp_inq_free(&ep->base.inqueue); 220 sctp_bind_addr_free(&ep->base.bind_addr); 221 222 memzero_explicit(&ep->cookie_auth_key, sizeof(ep->cookie_auth_key)); 223 224 sk = ep->base.sk; 225 /* Remove and free the port */ 226 if (sctp_sk(sk)->bind_hash) 227 sctp_put_port(sk); 228 229 call_rcu(&ep->rcu, sctp_endpoint_destroy_rcu); 230 } 231 232 /* Hold a reference to an endpoint. */ 233 int sctp_endpoint_hold(struct sctp_endpoint *ep) 234 { 235 return refcount_inc_not_zero(&ep->base.refcnt); 236 } 237 238 /* Release a reference to an endpoint and clean up if there are 239 * no more references. 240 */ 241 void sctp_endpoint_put(struct sctp_endpoint *ep) 242 { 243 if (refcount_dec_and_test(&ep->base.refcnt)) 244 sctp_endpoint_destroy(ep); 245 } 246 247 /* Is this the endpoint we are looking for? */ 248 struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep, 249 struct net *net, 250 const union sctp_addr *laddr, 251 int dif, int sdif) 252 { 253 int bound_dev_if = READ_ONCE(ep->base.sk->sk_bound_dev_if); 254 struct sctp_endpoint *retval = NULL; 255 256 if (net_eq(ep->base.net, net) && 257 sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) && 258 (htons(ep->base.bind_addr.port) == laddr->v4.sin_port)) { 259 if (sctp_bind_addr_match(&ep->base.bind_addr, laddr, 260 sctp_sk(ep->base.sk))) 261 retval = ep; 262 } 263 264 return retval; 265 } 266 267 /* Find the association that goes with this chunk. 268 * We lookup the transport from hashtable at first, then get association 269 * through t->assoc. 270 */ 271 struct sctp_association *sctp_endpoint_lookup_assoc( 272 const struct sctp_endpoint *ep, 273 const union sctp_addr *paddr, 274 struct sctp_transport **transport) 275 { 276 struct sctp_association *asoc = NULL; 277 struct sctp_transport *t; 278 279 *transport = NULL; 280 281 /* If the local port is not set, there can't be any associations 282 * on this endpoint. 283 */ 284 if (!ep->base.bind_addr.port) 285 return NULL; 286 287 rcu_read_lock(); 288 t = sctp_epaddr_lookup_transport(ep, paddr); 289 if (!t) 290 goto out; 291 292 *transport = t; 293 asoc = t->asoc; 294 out: 295 rcu_read_unlock(); 296 return asoc; 297 } 298 299 /* Look for any peeled off association from the endpoint that matches the 300 * given peer address. 301 */ 302 bool sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep, 303 const union sctp_addr *paddr) 304 { 305 int bound_dev_if = READ_ONCE(ep->base.sk->sk_bound_dev_if); 306 struct sctp_sockaddr_entry *addr; 307 struct net *net = ep->base.net; 308 struct sctp_bind_addr *bp; 309 310 bp = &ep->base.bind_addr; 311 /* This function is called with the socket lock held, 312 * so the address_list can not change. 313 */ 314 list_for_each_entry(addr, &bp->address_list, list) { 315 if (sctp_has_association(net, &addr->a, paddr, 316 bound_dev_if, bound_dev_if)) 317 return true; 318 } 319 320 return false; 321 } 322 323 /* Do delayed input processing. This is scheduled by sctp_rcv(). 324 * This may be called on BH or task time. 325 */ 326 static void sctp_endpoint_bh_rcv(struct work_struct *work) 327 { 328 struct sctp_endpoint *ep = 329 container_of(work, struct sctp_endpoint, 330 base.inqueue.immediate); 331 struct sctp_association *asoc; 332 struct sock *sk; 333 struct net *net; 334 struct sctp_transport *transport; 335 struct sctp_chunk *chunk; 336 struct sctp_inq *inqueue; 337 union sctp_subtype subtype; 338 enum sctp_state state; 339 int error = 0; 340 int first_time = 1; /* is this the first time through the loop */ 341 342 if (ep->base.dead) 343 return; 344 345 asoc = NULL; 346 inqueue = &ep->base.inqueue; 347 sk = ep->base.sk; 348 net = sock_net(sk); 349 350 while (NULL != (chunk = sctp_inq_pop(inqueue))) { 351 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type); 352 353 /* If the first chunk in the packet is AUTH, do special 354 * processing specified in Section 6.3 of SCTP-AUTH spec 355 */ 356 if (first_time && (subtype.chunk == SCTP_CID_AUTH)) { 357 struct sctp_chunkhdr *next_hdr; 358 359 next_hdr = sctp_inq_peek(inqueue); 360 if (!next_hdr) 361 goto normal; 362 363 /* If the next chunk is COOKIE-ECHO, skip the AUTH 364 * chunk while saving a pointer to it so we can do 365 * Authentication later (during cookie-echo 366 * processing). 367 */ 368 if (next_hdr->type == SCTP_CID_COOKIE_ECHO) { 369 chunk->auth_chunk = skb_clone(chunk->skb, 370 GFP_ATOMIC); 371 chunk->auth = 1; 372 continue; 373 } 374 } 375 normal: 376 /* We might have grown an association since last we 377 * looked, so try again. 378 * 379 * This happens when we've just processed our 380 * COOKIE-ECHO chunk. 381 */ 382 if (NULL == chunk->asoc) { 383 asoc = sctp_endpoint_lookup_assoc(ep, 384 sctp_source(chunk), 385 &transport); 386 chunk->asoc = asoc; 387 chunk->transport = transport; 388 } 389 390 state = asoc ? asoc->state : SCTP_STATE_CLOSED; 391 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth) 392 continue; 393 394 /* Remember where the last DATA chunk came from so we 395 * know where to send the SACK. 396 */ 397 if (asoc && sctp_chunk_is_data(chunk)) 398 asoc->peer.last_data_from = chunk->transport; 399 else { 400 SCTP_INC_STATS(ep->base.net, SCTP_MIB_INCTRLCHUNKS); 401 if (asoc) 402 asoc->stats.ictrlchunks++; 403 } 404 405 if (chunk->transport) 406 chunk->transport->last_time_heard = ktime_get(); 407 408 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state, 409 ep, asoc, chunk, GFP_ATOMIC); 410 411 if (error && chunk) 412 chunk->pdiscard = 1; 413 414 /* Check to see if the endpoint is freed in response to 415 * the incoming chunk. If so, get out of the while loop. 416 */ 417 if (!sctp_sk(sk)->ep) 418 break; 419 420 if (first_time) 421 first_time = 0; 422 } 423 } 424