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 /* path manager command handlers */
  14
  15 int mptcp_pm_announce_addr(struct mptcp_sock *msk,
  16                            const struct mptcp_addr_info *addr,
  17                            bool echo, bool port)
  18 {
  19         u8 add_addr = READ_ONCE(msk->pm.addr_signal);
  20
  21         pr_debug("msk=%p, local_id=%d", msk, addr->id);
  22
  23         lockdep_assert_held(&msk->pm.lock);
  24
  25         if (add_addr) {
  26                 pr_warn("addr_signal error, add_addr=%d", add_addr);
  27                 return -EINVAL;
  28         }
  29
  30         msk->pm.local = *addr;
  31         add_addr |= BIT(MPTCP_ADD_ADDR_SIGNAL);
  32         if (echo)
  33                 add_addr |= BIT(MPTCP_ADD_ADDR_ECHO);
  34         if (addr->family == AF_INET6)
  35                 add_addr |= BIT(MPTCP_ADD_ADDR_IPV6);
  36         if (port)
  37                 add_addr |= BIT(MPTCP_ADD_ADDR_PORT);
  38         WRITE_ONCE(msk->pm.addr_signal, add_addr);
  39         return 0;
  40 }
  41
  42 int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
  43 {
  44         u8 rm_addr = READ_ONCE(msk->pm.addr_signal);
  45
  46         pr_debug("msk=%p, local_id=%d", msk, local_id);
  47
  48         if (rm_addr) {
  49                 pr_warn("addr_signal error, rm_addr=%d", rm_addr);
  50                 return -EINVAL;
  51         }
  52
  53         msk->pm.rm_id = local_id;
  54         rm_addr |= BIT(MPTCP_RM_ADDR_SIGNAL);
  55         WRITE_ONCE(msk->pm.addr_signal, rm_addr);
  56         return 0;
  57 }
  58
  59 int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 local_id)
  60 {
  61         pr_debug("msk=%p, local_id=%d", msk, local_id);
  62
  63         spin_lock_bh(&msk->pm.lock);
  64         mptcp_pm_nl_rm_subflow_received(msk, local_id);
  65         spin_unlock_bh(&msk->pm.lock);
  66         return 0;
  67 }
  68
  69 /* path manager event handlers */
  70
  71 void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
  72 {
  73         struct mptcp_pm_data *pm = &msk->pm;
  74
  75         pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
  76
  77         WRITE_ONCE(pm->server_side, server_side);
  78 }
  79
  80 bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
  81 {
  82         struct mptcp_pm_data *pm = &msk->pm;
  83         unsigned int subflows_max;
  84         int ret = 0;
  85
  86         subflows_max = mptcp_pm_get_subflows_max(msk);
  87
  88         pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
  89                  subflows_max, READ_ONCE(pm->accept_subflow));
  90
  91         /* try to avoid acquiring the lock below */
  92         if (!READ_ONCE(pm->accept_subflow))
  93                 return false;
  94
  95         spin_lock_bh(&pm->lock);
  96         if (READ_ONCE(pm->accept_subflow)) {
  97                 ret = pm->subflows < subflows_max;
  98                 if (ret && ++pm->subflows == subflows_max)
  99                         WRITE_ONCE(pm->accept_subflow, false);
 100         }
 101         spin_unlock_bh(&pm->lock);
 102
 103         return ret;
 104 }
 105
 106 /* return true if the new status bit is currently cleared, that is, this event
 107  * can be server, eventually by an already scheduled work
 108  */
 109 static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
 110                                    enum mptcp_pm_status new_status)
 111 {
 112         pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
 113                  BIT(new_status));
 114         if (msk->pm.status & BIT(new_status))
 115                 return false;
 116
 117         msk->pm.status |= BIT(new_status);
 118         mptcp_schedule_work((struct sock *)msk);
 119         return true;
 120 }
 121
 122 void mptcp_pm_fully_established(struct mptcp_sock *msk)
 123 {
 124         struct mptcp_pm_data *pm = &msk->pm;
 125
 126         pr_debug("msk=%p", msk);
 127
 128         /* try to avoid acquiring the lock below */
 129         if (!READ_ONCE(pm->work_pending))
 130                 return;
 131
 132         spin_lock_bh(&pm->lock);
 133
 134         /* mptcp_pm_fully_established() can be invoked by multiple
 135          * racing paths - accept() and check_fully_established()
 136          * be sure to serve this event only once.
 137          */
 138         if (READ_ONCE(pm->work_pending) &&
 139             !(msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
 140                 mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 141         msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
 142
 143         spin_unlock_bh(&pm->lock);
 144 }
 145
 146 void mptcp_pm_connection_closed(struct mptcp_sock *msk)
 147 {
 148         pr_debug("msk=%p", msk);
 149 }
 150
 151 void mptcp_pm_subflow_established(struct mptcp_sock *msk,
 152                                   struct mptcp_subflow_context *subflow)
 153 {
 154         struct mptcp_pm_data *pm = &msk->pm;
 155
 156         pr_debug("msk=%p", msk);
 157
 158         if (!READ_ONCE(pm->work_pending))
 159                 return;
 160
 161         spin_lock_bh(&pm->lock);
 162
 163         if (READ_ONCE(pm->work_pending))
 164                 mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
 165
 166         spin_unlock_bh(&pm->lock);
 167 }
 168
 169 void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
 170 {
 171         pr_debug("msk=%p", msk);
 172 }
 173
 174 void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 175                                 const struct mptcp_addr_info *addr)
 176 {
 177         struct mptcp_pm_data *pm = &msk->pm;
 178
 179         pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
 180                  READ_ONCE(pm->accept_addr));
 181
 182         spin_lock_bh(&pm->lock);
 183
 184         if (!READ_ONCE(pm->accept_addr)) {
 185                 mptcp_pm_announce_addr(msk, addr, true, addr->port);
 186                 mptcp_pm_add_addr_send_ack(msk);
 187         } else if (mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED)) {
 188                 pm->remote = *addr;
 189         }
 190
 191         spin_unlock_bh(&pm->lock);
 192 }
 193
 194 void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
 195 {
 196         if (!mptcp_pm_should_add_signal(msk))
 197                 return;
 198
 199         mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_SEND_ACK);
 200 }
 201
 202 void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, u8 rm_id)
 203 {
 204         struct mptcp_pm_data *pm = &msk->pm;
 205
 206         pr_debug("msk=%p remote_id=%d", msk, rm_id);
 207
 208         spin_lock_bh(&pm->lock);
 209         mptcp_pm_schedule_work(msk, MPTCP_PM_RM_ADDR_RECEIVED);
 210         pm->rm_id = rm_id;
 211         spin_unlock_bh(&pm->lock);
 212 }
 213
 214 void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
 215 {
 216         struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 217
 218         pr_debug("subflow->backup=%d, bkup=%d\n", subflow->backup, bkup);
 219         subflow->backup = bkup;
 220 }
 221
 222 /* path manager helpers */
 223
 224 bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 225                               struct mptcp_addr_info *saddr, bool *echo, bool *port)
 226 {
 227         int ret = false;
 228
 229         spin_lock_bh(&msk->pm.lock);
 230
 231         /* double check after the lock is acquired */
 232         if (!mptcp_pm_should_add_signal(msk))
 233                 goto out_unlock;
 234
 235         *echo = mptcp_pm_should_add_signal_echo(msk);
 236         *port = mptcp_pm_should_add_signal_port(msk);
 237
 238         if (remaining < mptcp_add_addr_len(msk->pm.local.family, *echo, *port))
 239                 goto out_unlock;
 240
 241         *saddr = msk->pm.local;
 242         WRITE_ONCE(msk->pm.addr_signal, 0);
 243         ret = true;
 244
 245 out_unlock:
 246         spin_unlock_bh(&msk->pm.lock);
 247         return ret;
 248 }
 249
 250 bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
 251                              u8 *rm_id)
 252 {
 253         int ret = false;
 254
 255         spin_lock_bh(&msk->pm.lock);
 256
 257         /* double check after the lock is acquired */
 258         if (!mptcp_pm_should_rm_signal(msk))
 259                 goto out_unlock;
 260
 261         if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
 262                 goto out_unlock;
 263
 264         *rm_id = msk->pm.rm_id;
 265         WRITE_ONCE(msk->pm.addr_signal, 0);
 266         ret = true;
 267
 268 out_unlock:
 269         spin_unlock_bh(&msk->pm.lock);
 270         return ret;
 271 }
 272
 273 int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 274 {
 275         return mptcp_pm_nl_get_local_id(msk, skc);
 276 }
 277
 278 void mptcp_pm_data_init(struct mptcp_sock *msk)
 279 {
 280         msk->pm.add_addr_signaled = 0;
 281         msk->pm.add_addr_accepted = 0;
 282         msk->pm.local_addr_used = 0;
 283         msk->pm.subflows = 0;
 284         msk->pm.rm_id = 0;
 285         WRITE_ONCE(msk->pm.work_pending, false);
 286         WRITE_ONCE(msk->pm.addr_signal, 0);
 287         WRITE_ONCE(msk->pm.accept_addr, false);
 288         WRITE_ONCE(msk->pm.accept_subflow, false);
 289         msk->pm.status = 0;
 290
 291         spin_lock_init(&msk->pm.lock);
 292         INIT_LIST_HEAD(&msk->pm.anno_list);
 293
 294         mptcp_pm_nl_data_init(msk);
 295 }
 296
 297 void __init mptcp_pm_init(void)
 298 {
 299         mptcp_pm_nl_init();
 300 }