1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* SCTP kernel implementation 3 * (C) Copyright IBM Corp. 2003, 2004 4 * 5 * This file is part of the SCTP kernel implementation 6 * 7 * This file contains the code relating the chunk abstraction. 8 * 9 * Please send any bug reports or fixes you make to the 10 * email address(es): 11 * lksctp developers <linux-sctp@vger.kernel.org> 12 * 13 * Written or modified by: 14 * Jon Grimm <jgrimm@us.ibm.com> 15 * Sridhar Samudrala <sri@us.ibm.com> 16 */ 17 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 19 20 #include <linux/types.h> 21 #include <linux/kernel.h> 22 #include <linux/net.h> 23 #include <linux/inet.h> 24 #include <linux/skbuff.h> 25 #include <linux/slab.h> 26 #include <net/sock.h> 27 #include <net/sctp/sctp.h> 28 #include <net/sctp/sm.h> 29 30 /* This file is mostly in anticipation of future work, but initially 31 * populate with fragment tracking for an outbound message. 32 */ 33 34 /* Initialize datamsg from memory. */ 35 static void sctp_datamsg_init(struct sctp_datamsg *msg) 36 { 37 refcount_set(&msg->refcnt, 1); 38 msg->send_failed = 0; 39 msg->send_error = 0; 40 msg->can_delay = 1; 41 msg->abandoned = 0; 42 msg->expires_at = 0; 43 INIT_LIST_HEAD(&msg->chunks); 44 } 45 46 /* Allocate and initialize datamsg. */ 47 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp) 48 { 49 struct sctp_datamsg *msg; 50 msg = kmalloc(sizeof(struct sctp_datamsg), gfp); 51 if (msg) { 52 sctp_datamsg_init(msg); 53 SCTP_DBG_OBJCNT_INC(datamsg); 54 } 55 return msg; 56 } 57 58 void sctp_datamsg_free(struct sctp_datamsg *msg) 59 { 60 struct sctp_chunk *chunk; 61 62 /* This doesn't have to be a _safe vairant because 63 * sctp_chunk_free() only drops the refs. 64 */ 65 list_for_each_entry(chunk, &msg->chunks, frag_list) 66 sctp_chunk_free(chunk); 67 68 sctp_datamsg_put(msg); 69 } 70 71 /* Final destructruction of datamsg memory. */ 72 static void sctp_datamsg_destroy(struct sctp_datamsg *msg) 73 { 74 struct sctp_association *asoc = NULL; 75 struct list_head *pos, *temp; 76 struct sctp_chunk *chunk; 77 struct sctp_ulpevent *ev; 78 int error = 0, notify; 79 80 /* If we failed, we may need to notify. */ 81 notify = msg->send_failed ? -1 : 0; 82 83 /* Release all references. */ 84 list_for_each_safe(pos, temp, &msg->chunks) { 85 list_del_init(pos); 86 chunk = list_entry(pos, struct sctp_chunk, frag_list); 87 /* Check whether we _really_ need to notify. */ 88 if (notify < 0) { 89 asoc = chunk->asoc; 90 if (msg->send_error) 91 error = msg->send_error; 92 else 93 error = asoc->outqueue.error; 94 95 notify = sctp_ulpevent_type_enabled(asoc->subscribe, 96 SCTP_SEND_FAILED); 97 } 98 99 /* Generate a SEND FAILED event only if enabled. */ 100 if (notify > 0) { 101 int sent; 102 if (chunk->has_tsn) 103 sent = SCTP_DATA_SENT; 104 else 105 sent = SCTP_DATA_UNSENT; 106 107 ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent, 108 error, GFP_ATOMIC); 109 if (ev) 110 asoc->stream.si->enqueue_event(&asoc->ulpq, ev); 111 } 112 113 sctp_chunk_put(chunk); 114 } 115 116 SCTP_DBG_OBJCNT_DEC(datamsg); 117 kfree(msg); 118 } 119 120 /* Hold a reference. */ 121 static void sctp_datamsg_hold(struct sctp_datamsg *msg) 122 { 123 refcount_inc(&msg->refcnt); 124 } 125 126 /* Release a reference. */ 127 void sctp_datamsg_put(struct sctp_datamsg *msg) 128 { 129 if (refcount_dec_and_test(&msg->refcnt)) 130 sctp_datamsg_destroy(msg); 131 } 132 133 /* Assign a chunk to this datamsg. */ 134 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk) 135 { 136 sctp_datamsg_hold(msg); 137 chunk->msg = msg; 138 } 139 140 141 /* A data chunk can have a maximum payload of (2^16 - 20). Break 142 * down any such message into smaller chunks. Opportunistically, fragment 143 * the chunks down to the current MTU constraints. We may get refragmented 144 * later if the PMTU changes, but it is _much better_ to fragment immediately 145 * with a reasonable guess than always doing our fragmentation on the 146 * soft-interrupt. 147 */ 148 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, 149 struct sctp_sndrcvinfo *sinfo, 150 struct iov_iter *from) 151 { 152 size_t len, first_len, max_data, remaining; 153 size_t msg_len = iov_iter_count(from); 154 struct sctp_shared_key *shkey = NULL; 155 struct list_head *pos, *temp; 156 struct sctp_chunk *chunk; 157 struct sctp_datamsg *msg; 158 int err; 159 160 msg = sctp_datamsg_new(GFP_KERNEL); 161 if (!msg) 162 return ERR_PTR(-ENOMEM); 163 164 /* Note: Calculate this outside of the loop, so that all fragments 165 * have the same expiration. 166 */ 167 if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive && 168 (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) || 169 !SCTP_PR_POLICY(sinfo->sinfo_flags))) 170 msg->expires_at = jiffies + 171 msecs_to_jiffies(sinfo->sinfo_timetolive); 172 173 /* This is the biggest possible DATA chunk that can fit into 174 * the packet 175 */ 176 max_data = asoc->frag_point; 177 if (unlikely(!max_data)) { 178 max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk), 179 sctp_datachk_len(&asoc->stream)); 180 pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%zu)", 181 __func__, asoc, max_data); 182 } 183 184 /* If the the peer requested that we authenticate DATA chunks 185 * we need to account for bundling of the AUTH chunks along with 186 * DATA. 187 */ 188 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) { 189 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc); 190 191 if (hmac_desc) 192 max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) + 193 hmac_desc->hmac_len); 194 195 if (sinfo->sinfo_tsn && 196 sinfo->sinfo_ssn != asoc->active_key_id) { 197 shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn); 198 if (!shkey) { 199 err = -EINVAL; 200 goto errout; 201 } 202 } else { 203 shkey = asoc->shkey; 204 } 205 } 206 207 /* Set first_len and then account for possible bundles on first frag */ 208 first_len = max_data; 209 210 /* Check to see if we have a pending SACK and try to let it be bundled 211 * with this message. Do this if we don't have any data queued already. 212 * To check that, look at out_qlen and retransmit list. 213 * NOTE: we will not reduce to account for SACK, if the message would 214 * not have been fragmented. 215 */ 216 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) && 217 asoc->outqueue.out_qlen == 0 && 218 list_empty(&asoc->outqueue.retransmit) && 219 msg_len > max_data) 220 first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk)); 221 222 /* Encourage Cookie-ECHO bundling. */ 223 if (asoc->state < SCTP_STATE_COOKIE_ECHOED) 224 first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN; 225 226 /* Account for a different sized first fragment */ 227 if (msg_len >= first_len) { 228 msg->can_delay = 0; 229 if (msg_len > first_len) 230 SCTP_INC_STATS(sock_net(asoc->base.sk), 231 SCTP_MIB_FRAGUSRMSGS); 232 } else { 233 /* Which may be the only one... */ 234 first_len = msg_len; 235 } 236 237 /* Create chunks for all DATA chunks. */ 238 for (remaining = msg_len; remaining; remaining -= len) { 239 u8 frag = SCTP_DATA_MIDDLE_FRAG; 240 241 if (remaining == msg_len) { 242 /* First frag, which may also be the last */ 243 frag |= SCTP_DATA_FIRST_FRAG; 244 len = first_len; 245 } else { 246 /* Middle frags */ 247 len = max_data; 248 } 249 250 if (len >= remaining) { 251 /* Last frag, which may also be the first */ 252 len = remaining; 253 frag |= SCTP_DATA_LAST_FRAG; 254 255 /* The application requests to set the I-bit of the 256 * last DATA chunk of a user message when providing 257 * the user message to the SCTP implementation. 258 */ 259 if ((sinfo->sinfo_flags & SCTP_EOF) || 260 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY)) 261 frag |= SCTP_DATA_SACK_IMM; 262 } 263 264 chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag, 265 GFP_KERNEL); 266 if (!chunk) { 267 err = -ENOMEM; 268 goto errout; 269 } 270 271 err = sctp_user_addto_chunk(chunk, len, from); 272 if (err < 0) 273 goto errout_chunk_free; 274 275 chunk->shkey = shkey; 276 277 /* Put the chunk->skb back into the form expected by send. */ 278 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr - 279 chunk->skb->data); 280 281 sctp_datamsg_assign(msg, chunk); 282 list_add_tail(&chunk->frag_list, &msg->chunks); 283 } 284 285 return msg; 286 287 errout_chunk_free: 288 sctp_chunk_free(chunk); 289 290 errout: 291 list_for_each_safe(pos, temp, &msg->chunks) { 292 list_del_init(pos); 293 chunk = list_entry(pos, struct sctp_chunk, frag_list); 294 sctp_chunk_free(chunk); 295 } 296 sctp_datamsg_put(msg); 297 298 return ERR_PTR(err); 299 } 300 301 /* Check whether this message has expired. */ 302 int sctp_chunk_abandoned(struct sctp_chunk *chunk) 303 { 304 if (!chunk->asoc->peer.prsctp_capable) 305 return 0; 306 307 if (chunk->msg->abandoned) 308 return 1; 309 310 if (!chunk->has_tsn && 311 !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG)) 312 return 0; 313 314 if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) && 315 time_after(jiffies, chunk->msg->expires_at)) { 316 struct sctp_stream_out *streamout = 317 SCTP_SO(&chunk->asoc->stream, 318 chunk->sinfo.sinfo_stream); 319 320 if (chunk->sent_count) { 321 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++; 322 streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++; 323 } else { 324 chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++; 325 streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++; 326 } 327 chunk->msg->abandoned = 1; 328 return 1; 329 } else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) && 330 chunk->sent_count > chunk->sinfo.sinfo_timetolive) { 331 struct sctp_stream_out *streamout = 332 SCTP_SO(&chunk->asoc->stream, 333 chunk->sinfo.sinfo_stream); 334 335 chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++; 336 streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++; 337 chunk->msg->abandoned = 1; 338 return 1; 339 } else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) && 340 chunk->msg->expires_at && 341 time_after(jiffies, chunk->msg->expires_at)) { 342 chunk->msg->abandoned = 1; 343 return 1; 344 } 345 /* PRIO policy is processed by sendmsg, not here */ 346 347 return 0; 348 } 349 350 /* This chunk (and consequently entire message) has failed in its sending. */ 351 void sctp_chunk_fail(struct sctp_chunk *chunk, int error) 352 { 353 chunk->msg->send_failed = 1; 354 chunk->msg->send_error = error; 355 } 356