net/mptcp/pm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Multipath TCP
   3  *
   4  * Copyright (c) 2019, Intel Corporation.
   5  */
   6 #define pr_fmt(fmt) "MPTCP: " fmt
   7
   8 #include <linux/kernel.h>
   9 #include <net/tcp.h>
  10 #include <net/mptcp.h>
  11 #include "protocol.h"
  12
  13 #include "mib.h"
  14
  15 /* path manager command handlers */
  16
  17 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
  18                            const struct mptcp_addr_info *addr,
  19                            bool echo)
  20 {
  21         u8 add_addr = READ_ONCE(msk->pm.addr_signal);
  22
  23         pr_debug("msk=%p, local_id=%d, echo=%d", msk, addr->id, echo);
  24
  25         lockdep_assert_held(&msk->pm.lock);
  26
  27         if (add_addr &
  28             (echo ? BIT(MPTCP_ADD_ADDR_ECHO) : BIT(MPTCP_ADD_ADDR_SIGNAL))) {
  29                 pr_warn("addr_signal error, add_addr=%d, echo=%d", add_addr, echo);
  30                 return -EINVAL;
  31         }
  32
  33         if (echo) {
  34                 msk->pm.remote = *addr;
  35                 add_addr |= BIT(MPTCP_ADD_ADDR_ECHO);
  36         } else {
  37                 msk->pm.local = *addr;
  38                 add_addr |= BIT(MPTCP_ADD_ADDR_SIGNAL);
  39         }
  40         WRITE_ONCE(msk->pm.addr_signal, add_addr);
  41         return 0;
  42 }
  43
  44 int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list)
  45 {
  46         u8 rm_addr = READ_ONCE(msk->pm.addr_signal);
  47
  48         pr_debug("msk=%p, rm_list_nr=%d", msk, rm_list->nr);
  49
  50         if (rm_addr) {
  51                 pr_warn("addr_signal error, rm_addr=%d", rm_addr);
  52                 return -EINVAL;
  53         }
  54
  55         msk->pm.rm_list_tx = *rm_list;
  56         rm_addr |= BIT(MPTCP_RM_ADDR_SIGNAL);
  57         WRITE_ONCE(msk->pm.addr_signal, rm_addr);
  58         mptcp_pm_nl_addr_send_ack(msk);
  59         return 0;
  60 }
  61
  62 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list)
  63 {
  64         pr_debug("msk=%p, rm_list_nr=%d", msk, rm_list->nr);
  65
  66         spin_lock_bh(&msk->pm.lock);
  67         mptcp_pm_nl_rm_subflow_received(msk, rm_list);
  68         spin_unlock_bh(&msk->pm.lock);
  69         return 0;
  70 }
  71
  72 /* path manager event handlers */
  73
  74 void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side)
  75 {
  76         struct mptcp_pm_data *pm = &msk->pm;
  77
  78         pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
  79
  80         WRITE_ONCE(pm->server_side, server_side);
  81         mptcp_event(MPTCP_EVENT_CREATED, msk, ssk, GFP_ATOMIC);
  82 }
  83
  84 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
  85 {
  86         struct mptcp_pm_data *pm = &msk->pm;
  87         unsigned int subflows_max;
  88         int ret = 0;
  89
  90         if (mptcp_pm_is_userspace(msk))
  91                 return mptcp_userspace_pm_active(msk);
  92
  93         subflows_max = mptcp_pm_get_subflows_max(msk);
  94
  95         pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
  96                  subflows_max, READ_ONCE(pm->accept_subflow));
  97
  98         /* try to avoid acquiring the lock below */
  99         if (!READ_ONCE(pm->accept_subflow))
 100                 return false;
 101
 102         spin_lock_bh(&pm->lock);
 103         if (READ_ONCE(pm->accept_subflow)) {
 104                 ret = pm->subflows < subflows_max;
 105                 if (ret && ++pm->subflows == subflows_max)
 106                         WRITE_ONCE(pm->accept_subflow, false);
 107         }
 108         spin_unlock_bh(&pm->lock);
 109
 110         return ret;
 111 }
 112
 113 /* return true if the new status bit is currently cleared, that is, this event
 114  * can be server, eventually by an already scheduled work
 115  */
 116 static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
 117                                    enum mptcp_pm_status new_status)
 118 {
 119         pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
 120                  BIT(new_status));
 121         if (msk->pm.status & BIT(new_status))
 122                 return false;
 123
 124         msk->pm.status |= BIT(new_status);
 125         mptcp_schedule_work((struct sock *)msk);
 126         return true;
 127 }
 128
 129 void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp)
 130 {
 131         struct mptcp_pm_data *pm = &msk->pm;
 132         bool announce = false;
 133
 134         pr_debug("msk=%p", msk);
 135
 136         spin_lock_bh(&pm->lock);
 137
 138         /* mptcp_pm_fully_established() can be invoked by multiple
 139          * racing paths - accept() and check_fully_established()
 140          * be sure to serve this event only once.
 141          */
 142         if (READ_ONCE(pm->work_pending) &&
 143             !(msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
 144                 mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 145
 146         if ((msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
 147                 announce = true;
 148
 149         msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
 150         spin_unlock_bh(&pm->lock);
 151
 152         if (announce)
 153                 mptcp_event(MPTCP_EVENT_ESTABLISHED, msk, ssk, gfp);
 154 }
 155
 156 void mptcp_pm_connection_closed(struct mptcp_sock *msk)
 157 {
 158         pr_debug("msk=%p", msk);
 159 }
 160
 161 void mptcp_pm_subflow_established(struct mptcp_sock *msk)
 162 {
 163         struct mptcp_pm_data *pm = &msk->pm;
 164
 165         pr_debug("msk=%p", msk);
 166
 167         if (!READ_ONCE(pm->work_pending))
 168                 return;
 169
 170         spin_lock_bh(&pm->lock);
 171
 172         if (READ_ONCE(pm->work_pending))
 173                 mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
 174
 175         spin_unlock_bh(&pm->lock);
 176 }
 177
 178 void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct sock *ssk,
 179                                  const struct mptcp_subflow_context *subflow)
 180 {
 181         struct mptcp_pm_data *pm = &msk->pm;
 182         bool update_subflows;
 183
 184         update_subflows = (subflow->request_join || subflow->mp_join) &&
 185                           mptcp_pm_is_kernel(msk);
 186         if (!READ_ONCE(pm->work_pending) && !update_subflows)
 187                 return;
 188
 189         spin_lock_bh(&pm->lock);
 190         if (update_subflows)
 191                 __mptcp_pm_close_subflow(msk);
 192
 193         /* Even if this subflow is not really established, tell the PM to try
 194          * to pick the next ones, if possible.
 195          */
 196         if (mptcp_pm_nl_check_work_pending(msk))
 197                 mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
 198
 199         spin_unlock_bh(&pm->lock);
 200 }
 201
 202 void mptcp_pm_add_addr_received(const struct sock *ssk,
 203                                 const struct mptcp_addr_info *addr)
 204 {
 205         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 206         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 207         struct mptcp_pm_data *pm = &msk->pm;
 208
 209         pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
 210                  READ_ONCE(pm->accept_addr));
 211
 212         mptcp_event_addr_announced(ssk, addr);
 213
 214         spin_lock_bh(&pm->lock);
 215
 216         if (mptcp_pm_is_userspace(msk)) {
 217                 if (mptcp_userspace_pm_active(msk)) {
 218                         mptcp_pm_announce_addr(msk, addr, true);
 219                         mptcp_pm_add_addr_send_ack(msk);
 220                 } else {
 221                         __MPTCP_INC_STATS(sock_net((struct sock *)msk), MPTCP_MIB_ADDADDRDROP);
 222                 }
 223         } else if (!READ_ONCE(pm->accept_addr)) {
 224                 mptcp_pm_announce_addr(msk, addr, true);
 225                 mptcp_pm_add_addr_send_ack(msk);
 226         } else if (mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED)) {
 227                 pm->remote = *addr;
 228         } else {
 229                 __MPTCP_INC_STATS(sock_net((struct sock *)msk), MPTCP_MIB_ADDADDRDROP);
 230         }
 231
 232         spin_unlock_bh(&pm->lock);
 233 }
 234
 235 void mptcp_pm_add_addr_echoed(struct mptcp_sock *msk,
 236                               const struct mptcp_addr_info *addr)
 237 {
 238         struct mptcp_pm_data *pm = &msk->pm;
 239
 240         pr_debug("msk=%p", msk);
 241
 242         spin_lock_bh(&pm->lock);
 243
 244         if (mptcp_lookup_anno_list_by_saddr(msk, addr) && READ_ONCE(pm->work_pending))
 245                 mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
 246
 247         spin_unlock_bh(&pm->lock);
 248 }
 249
 250 void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
 251 {
 252         if (!mptcp_pm_should_add_signal(msk))
 253                 return;
 254
 255         mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_SEND_ACK);
 256 }
 257
 258 void mptcp_pm_rm_addr_received(struct mptcp_sock *msk,
 259                                const struct mptcp_rm_list *rm_list)
 260 {
 261         struct mptcp_pm_data *pm = &msk->pm;
 262         u8 i;
 263
 264         pr_debug("msk=%p remote_ids_nr=%d", msk, rm_list->nr);
 265
 266         for (i = 0; i < rm_list->nr; i++)
 267                 mptcp_event_addr_removed(msk, rm_list->ids[i]);
 268
 269         spin_lock_bh(&pm->lock);
 270         if (mptcp_pm_schedule_work(msk, MPTCP_PM_RM_ADDR_RECEIVED))
 271                 pm->rm_list_rx = *rm_list;
 272         else
 273                 __MPTCP_INC_STATS(sock_net((struct sock *)msk), MPTCP_MIB_RMADDRDROP);
 274         spin_unlock_bh(&pm->lock);
 275 }
 276
 277 void mptcp_pm_mp_prio_received(struct sock *ssk, u8 bkup)
 278 {
 279         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 280         struct sock *sk = subflow->conn;
 281         struct mptcp_sock *msk;
 282
 283         pr_debug("subflow->backup=%d, bkup=%d\n", subflow->backup, bkup);
 284         msk = mptcp_sk(sk);
 285         if (subflow->backup != bkup) {
 286                 subflow->backup = bkup;
 287                 mptcp_data_lock(sk);
 288                 if (!sock_owned_by_user(sk))
 289                         msk->last_snd = NULL;
 290                 else
 291                         __set_bit(MPTCP_RESET_SCHEDULER,  &msk->cb_flags);
 292                 mptcp_data_unlock(sk);
 293         }
 294
 295         mptcp_event(MPTCP_EVENT_SUB_PRIORITY, msk, ssk, GFP_ATOMIC);
 296 }
 297
 298 void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
 299 {
 300         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 301         struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 302
 303         pr_debug("fail_seq=%llu", fail_seq);
 304
 305         if (!READ_ONCE(msk->allow_infinite_fallback))
 306                 return;
 307
 308         if (!subflow->fail_tout) {
 309                 pr_debug("send MP_FAIL response and infinite map");
 310
 311                 subflow->send_mp_fail = 1;
 312                 subflow->send_infinite_map = 1;
 313                 tcp_send_ack(sk);
 314         } else {
 315                 pr_debug("MP_FAIL response received");
 316                 WRITE_ONCE(subflow->fail_tout, 0);
 317         }
 318 }
 319
 320 /* path manager helpers */
 321
 322 bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, const struct sk_buff *skb,
 323                               unsigned int opt_size, unsigned int remaining,
 324                               struct mptcp_addr_info *addr, bool *echo,
 325                               bool *drop_other_suboptions)
 326 {
 327         int ret = false;
 328         u8 add_addr;
 329         u8 family;
 330         bool port;
 331
 332         spin_lock_bh(&msk->pm.lock);
 333
 334         /* double check after the lock is acquired */
 335         if (!mptcp_pm_should_add_signal(msk))
 336                 goto out_unlock;
 337
 338         /* always drop every other options for pure ack ADD_ADDR; this is a
 339          * plain dup-ack from TCP perspective. The other MPTCP-relevant info,
 340          * if any, will be carried by the 'original' TCP ack
 341          */
 342         if (skb && skb_is_tcp_pure_ack(skb)) {
 343                 remaining += opt_size;
 344                 *drop_other_suboptions = true;
 345         }
 346
 347         *echo = mptcp_pm_should_add_signal_echo(msk);
 348         port = !!(*echo ? msk->pm.remote.port : msk->pm.local.port);
 349
 350         family = *echo ? msk->pm.remote.family : msk->pm.local.family;
 351         if (remaining < mptcp_add_addr_len(family, *echo, port))
 352                 goto out_unlock;
 353
 354         if (*echo) {
 355                 *addr = msk->pm.remote;
 356                 add_addr = msk->pm.addr_signal & ~BIT(MPTCP_ADD_ADDR_ECHO);
 357         } else {
 358                 *addr = msk->pm.local;
 359                 add_addr = msk->pm.addr_signal & ~BIT(MPTCP_ADD_ADDR_SIGNAL);
 360         }
 361         WRITE_ONCE(msk->pm.addr_signal, add_addr);
 362         ret = true;
 363
 364 out_unlock:
 365         spin_unlock_bh(&msk->pm.lock);
 366         return ret;
 367 }
 368
 369 bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 370                              struct mptcp_rm_list *rm_list)
 371 {
 372         int ret = false, len;
 373         u8 rm_addr;
 374
 375         spin_lock_bh(&msk->pm.lock);
 376
 377         /* double check after the lock is acquired */
 378         if (!mptcp_pm_should_rm_signal(msk))
 379                 goto out_unlock;
 380
 381         rm_addr = msk->pm.addr_signal & ~BIT(MPTCP_RM_ADDR_SIGNAL);
 382         len = mptcp_rm_addr_len(&msk->pm.rm_list_tx);
 383         if (len < 0) {
 384                 WRITE_ONCE(msk->pm.addr_signal, rm_addr);
 385                 goto out_unlock;
 386         }
 387         if (remaining < len)
 388                 goto out_unlock;
 389
 390         *rm_list = msk->pm.rm_list_tx;
 391         WRITE_ONCE(msk->pm.addr_signal, rm_addr);
 392         ret = true;
 393
 394 out_unlock:
 395         spin_unlock_bh(&msk->pm.lock);
 396         return ret;
 397 }
 398
 399 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 400 {
 401         return mptcp_pm_nl_get_local_id(msk, skc);
 402 }
 403
 404 void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
 405 {
 406         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
 407         u32 rcv_tstamp = READ_ONCE(tcp_sk(ssk)->rcv_tstamp);
 408
 409         /* keep track of rtx periods with no progress */
 410         if (!subflow->stale_count) {
 411                 subflow->stale_rcv_tstamp = rcv_tstamp;
 412                 subflow->stale_count++;
 413         } else if (subflow->stale_rcv_tstamp == rcv_tstamp) {
 414                 if (subflow->stale_count < U8_MAX)
 415                         subflow->stale_count++;
 416                 mptcp_pm_nl_subflow_chk_stale(msk, ssk);
 417         } else {
 418                 subflow->stale_count = 0;
 419                 mptcp_subflow_set_active(subflow);
 420         }
 421 }
 422
 423 void mptcp_pm_data_reset(struct mptcp_sock *msk)
 424 {
 425         u8 pm_type = mptcp_get_pm_type(sock_net((struct sock *)msk));
 426         struct mptcp_pm_data *pm = &msk->pm;
 427
 428         pm->add_addr_signaled = 0;
 429         pm->add_addr_accepted = 0;
 430         pm->local_addr_used = 0;
 431         pm->subflows = 0;
 432         pm->rm_list_tx.nr = 0;
 433         pm->rm_list_rx.nr = 0;
 434         WRITE_ONCE(pm->pm_type, pm_type);
 435
 436         if (pm_type == MPTCP_PM_TYPE_KERNEL) {
 437                 bool subflows_allowed = !!mptcp_pm_get_subflows_max(msk);
 438
 439                 /* pm->work_pending must be only be set to 'true' when
 440                  * pm->pm_type is set to MPTCP_PM_TYPE_KERNEL
 441                  */
 442                 WRITE_ONCE(pm->work_pending,
 443                            (!!mptcp_pm_get_local_addr_max(msk) &&
 444                             subflows_allowed) ||
 445                            !!mptcp_pm_get_add_addr_signal_max(msk));
 446                 WRITE_ONCE(pm->accept_addr,
 447                            !!mptcp_pm_get_add_addr_accept_max(msk) &&
 448                            subflows_allowed);
 449                 WRITE_ONCE(pm->accept_subflow, subflows_allowed);
 450         } else {
 451                 WRITE_ONCE(pm->work_pending, 0);
 452                 WRITE_ONCE(pm->accept_addr, 0);
 453                 WRITE_ONCE(pm->accept_subflow, 0);
 454         }
 455
 456         WRITE_ONCE(pm->addr_signal, 0);
 457         WRITE_ONCE(pm->remote_deny_join_id0, false);
 458         pm->status = 0;
 459         bitmap_fill(msk->pm.id_avail_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
 460 }
 461
 462 void mptcp_pm_data_init(struct mptcp_sock *msk)
 463 {
 464         spin_lock_init(&msk->pm.lock);
 465         INIT_LIST_HEAD(&msk->pm.anno_list);
 466         INIT_LIST_HEAD(&msk->pm.userspace_pm_local_addr_list);
 467         mptcp_pm_data_reset(msk);
 468 }
 469
 470 void __init mptcp_pm_init(void)
 471 {
 472         mptcp_pm_nl_init();
 473 }