io_uring/cancel.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/errno.h>
   4 #include <linux/fs.h>
   5 #include <linux/file.h>
   6 #include <linux/mm.h>
   7 #include <linux/slab.h>
   8 #include <linux/namei.h>
   9 #include <linux/nospec.h>
  10 #include <linux/io_uring.h>
  11
  12 #include <uapi/linux/io_uring.h>
  13
  14 #include "io_uring.h"
  15 #include "tctx.h"
  16 #include "poll.h"
  17 #include "timeout.h"
  18 #include "waitid.h"
  19 #include "futex.h"
  20 #include "cancel.h"
  21
  22 struct io_cancel {
  23         struct file                     *file;
  24         u64                             addr;
  25         u32                             flags;
  26         s32                             fd;
  27         u8                              opcode;
  28 };
  29
  30 #define CANCEL_FLAGS    (IORING_ASYNC_CANCEL_ALL | IORING_ASYNC_CANCEL_FD | \
  31                          IORING_ASYNC_CANCEL_ANY | IORING_ASYNC_CANCEL_FD_FIXED | \
  32                          IORING_ASYNC_CANCEL_USERDATA | IORING_ASYNC_CANCEL_OP)
  33
  34 /*
  35  * Returns true if the request matches the criteria outlined by 'cd'.
  36  */
  37 bool io_cancel_req_match(struct io_kiocb *req, struct io_cancel_data *cd)
  38 {
  39         bool match_user_data = cd->flags & IORING_ASYNC_CANCEL_USERDATA;
  40
  41         if (req->ctx != cd->ctx)
  42                 return false;
  43
  44         if (!(cd->flags & (IORING_ASYNC_CANCEL_FD | IORING_ASYNC_CANCEL_OP)))
  45                 match_user_data = true;
  46
  47         if (cd->flags & IORING_ASYNC_CANCEL_ANY)
  48                 goto check_seq;
  49         if (cd->flags & IORING_ASYNC_CANCEL_FD) {
  50                 if (req->file != cd->file)
  51                         return false;
  52         }
  53         if (cd->flags & IORING_ASYNC_CANCEL_OP) {
  54                 if (req->opcode != cd->opcode)
  55                         return false;
  56         }
  57         if (match_user_data && req->cqe.user_data != cd->data)
  58                 return false;
  59         if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
  60 check_seq:
  61                 if (io_cancel_match_sequence(req, cd->seq))
  62                         return false;
  63         }
  64
  65         return true;
  66 }
  67
  68 static bool io_cancel_cb(struct io_wq_work *work, void *data)
  69 {
  70         struct io_kiocb *req = container_of(work, struct io_kiocb, work);
  71         struct io_cancel_data *cd = data;
  72
  73         return io_cancel_req_match(req, cd);
  74 }
  75
  76 static int io_async_cancel_one(struct io_uring_task *tctx,
  77                                struct io_cancel_data *cd)
  78 {
  79         enum io_wq_cancel cancel_ret;
  80         int ret = 0;
  81         bool all;
  82
  83         if (!tctx || !tctx->io_wq)
  84                 return -ENOENT;
  85
  86         all = cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY);
  87         cancel_ret = io_wq_cancel_cb(tctx->io_wq, io_cancel_cb, cd, all);
  88         switch (cancel_ret) {
  89         case IO_WQ_CANCEL_OK:
  90                 ret = 0;
  91                 break;
  92         case IO_WQ_CANCEL_RUNNING:
  93                 ret = -EALREADY;
  94                 break;
  95         case IO_WQ_CANCEL_NOTFOUND:
  96                 ret = -ENOENT;
  97                 break;
  98         }
  99
 100         return ret;
 101 }
 102
 103 int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd,
 104                   unsigned issue_flags)
 105 {
 106         struct io_ring_ctx *ctx = cd->ctx;
 107         int ret;
 108
 109         WARN_ON_ONCE(!io_wq_current_is_worker() && tctx != current->io_uring);
 110
 111         ret = io_async_cancel_one(tctx, cd);
 112         /*
 113          * Fall-through even for -EALREADY, as we may have poll armed
 114          * that need unarming.
 115          */
 116         if (!ret)
 117                 return 0;
 118
 119         ret = io_poll_cancel(ctx, cd, issue_flags);
 120         if (ret != -ENOENT)
 121                 return ret;
 122
 123         ret = io_waitid_cancel(ctx, cd, issue_flags);
 124         if (ret != -ENOENT)
 125                 return ret;
 126
 127         ret = io_futex_cancel(ctx, cd, issue_flags);
 128         if (ret != -ENOENT)
 129                 return ret;
 130
 131         spin_lock(&ctx->completion_lock);
 132         if (!(cd->flags & IORING_ASYNC_CANCEL_FD))
 133                 ret = io_timeout_cancel(ctx, cd);
 134         spin_unlock(&ctx->completion_lock);
 135         return ret;
 136 }
 137
 138 int io_async_cancel_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 139 {
 140         struct io_cancel *cancel = io_kiocb_to_cmd(req, struct io_cancel);
 141
 142         if (unlikely(req->flags & REQ_F_BUFFER_SELECT))
 143                 return -EINVAL;
 144         if (sqe->off || sqe->splice_fd_in)
 145                 return -EINVAL;
 146
 147         cancel->addr = READ_ONCE(sqe->addr);
 148         cancel->flags = READ_ONCE(sqe->cancel_flags);
 149         if (cancel->flags & ~CANCEL_FLAGS)
 150                 return -EINVAL;
 151         if (cancel->flags & IORING_ASYNC_CANCEL_FD) {
 152                 if (cancel->flags & IORING_ASYNC_CANCEL_ANY)
 153                         return -EINVAL;
 154                 cancel->fd = READ_ONCE(sqe->fd);
 155         }
 156         if (cancel->flags & IORING_ASYNC_CANCEL_OP) {
 157                 if (cancel->flags & IORING_ASYNC_CANCEL_ANY)
 158                         return -EINVAL;
 159                 cancel->opcode = READ_ONCE(sqe->len);
 160         }
 161
 162         return 0;
 163 }
 164
 165 static int __io_async_cancel(struct io_cancel_data *cd,
 166                              struct io_uring_task *tctx,
 167                              unsigned int issue_flags)
 168 {
 169         bool all = cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY);
 170         struct io_ring_ctx *ctx = cd->ctx;
 171         struct io_tctx_node *node;
 172         int ret, nr = 0;
 173
 174         do {
 175                 ret = io_try_cancel(tctx, cd, issue_flags);
 176                 if (ret == -ENOENT)
 177                         break;
 178                 if (!all)
 179                         return ret;
 180                 nr++;
 181         } while (1);
 182
 183         /* slow path, try all io-wq's */
 184         io_ring_submit_lock(ctx, issue_flags);
 185         ret = -ENOENT;
 186         list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
 187                 ret = io_async_cancel_one(node->task->io_uring, cd);
 188                 if (ret != -ENOENT) {
 189                         if (!all)
 190                                 break;
 191                         nr++;
 192                 }
 193         }
 194         io_ring_submit_unlock(ctx, issue_flags);
 195         return all ? nr : ret;
 196 }
 197
 198 int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 199 {
 200         struct io_cancel *cancel = io_kiocb_to_cmd(req, struct io_cancel);
 201         struct io_cancel_data cd = {
 202                 .ctx    = req->ctx,
 203                 .data   = cancel->addr,
 204                 .flags  = cancel->flags,
 205                 .opcode = cancel->opcode,
 206                 .seq    = atomic_inc_return(&req->ctx->cancel_seq),
 207         };
 208         struct io_uring_task *tctx = req->task->io_uring;
 209         int ret;
 210
 211         if (cd.flags & IORING_ASYNC_CANCEL_FD) {
 212                 if (req->flags & REQ_F_FIXED_FILE ||
 213                     cd.flags & IORING_ASYNC_CANCEL_FD_FIXED) {
 214                         req->flags |= REQ_F_FIXED_FILE;
 215                         req->file = io_file_get_fixed(req, cancel->fd,
 216                                                         issue_flags);
 217                 } else {
 218                         req->file = io_file_get_normal(req, cancel->fd);
 219                 }
 220                 if (!req->file) {
 221                         ret = -EBADF;
 222                         goto done;
 223                 }
 224                 cd.file = req->file;
 225         }
 226
 227         ret = __io_async_cancel(&cd, tctx, issue_flags);
 228 done:
 229         if (ret < 0)
 230                 req_set_fail(req);
 231         io_req_set_res(req, ret, 0);
 232         return IOU_OK;
 233 }
 234
 235 void init_hash_table(struct io_hash_table *table, unsigned size)
 236 {
 237         unsigned int i;
 238
 239         for (i = 0; i < size; i++) {
 240                 spin_lock_init(&table->hbs[i].lock);
 241                 INIT_HLIST_HEAD(&table->hbs[i].list);
 242         }
 243 }
 244
 245 static int __io_sync_cancel(struct io_uring_task *tctx,
 246                             struct io_cancel_data *cd, int fd)
 247 {
 248         struct io_ring_ctx *ctx = cd->ctx;
 249
 250         /* fixed must be grabbed every time since we drop the uring_lock */
 251         if ((cd->flags & IORING_ASYNC_CANCEL_FD) &&
 252             (cd->flags & IORING_ASYNC_CANCEL_FD_FIXED)) {
 253                 if (unlikely(fd >= ctx->nr_user_files))
 254                         return -EBADF;
 255                 fd = array_index_nospec(fd, ctx->nr_user_files);
 256                 cd->file = io_file_from_index(&ctx->file_table, fd);
 257                 if (!cd->file)
 258                         return -EBADF;
 259         }
 260
 261         return __io_async_cancel(cd, tctx, 0);
 262 }
 263
 264 int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg)
 265         __must_hold(&ctx->uring_lock)
 266 {
 267         struct io_cancel_data cd = {
 268                 .ctx    = ctx,
 269                 .seq    = atomic_inc_return(&ctx->cancel_seq),
 270         };
 271         ktime_t timeout = KTIME_MAX;
 272         struct io_uring_sync_cancel_reg sc;
 273         struct file *file = NULL;
 274         DEFINE_WAIT(wait);
 275         int ret, i;
 276
 277         if (copy_from_user(&sc, arg, sizeof(sc)))
 278                 return -EFAULT;
 279         if (sc.flags & ~CANCEL_FLAGS)
 280                 return -EINVAL;
 281         for (i = 0; i < ARRAY_SIZE(sc.pad); i++)
 282                 if (sc.pad[i])
 283                         return -EINVAL;
 284         for (i = 0; i < ARRAY_SIZE(sc.pad2); i++)
 285                 if (sc.pad2[i])
 286                         return -EINVAL;
 287
 288         cd.data = sc.addr;
 289         cd.flags = sc.flags;
 290         cd.opcode = sc.opcode;
 291
 292         /* we can grab a normal file descriptor upfront */
 293         if ((cd.flags & IORING_ASYNC_CANCEL_FD) &&
 294            !(cd.flags & IORING_ASYNC_CANCEL_FD_FIXED)) {
 295                 file = fget(sc.fd);
 296                 if (!file)
 297                         return -EBADF;
 298                 cd.file = file;
 299         }
 300
 301         ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);
 302
 303         /* found something, done! */
 304         if (ret != -EALREADY)
 305                 goto out;
 306
 307         if (sc.timeout.tv_sec != -1UL || sc.timeout.tv_nsec != -1UL) {
 308                 struct timespec64 ts = {
 309                         .tv_sec         = sc.timeout.tv_sec,
 310                         .tv_nsec        = sc.timeout.tv_nsec
 311                 };
 312
 313                 timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
 314         }
 315
 316         /*
 317          * Keep looking until we get -ENOENT. we'll get woken everytime
 318          * every time a request completes and will retry the cancelation.
 319          */
 320         do {
 321                 cd.seq = atomic_inc_return(&ctx->cancel_seq);
 322
 323                 prepare_to_wait(&ctx->cq_wait, &wait, TASK_INTERRUPTIBLE);
 324
 325                 ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);
 326
 327                 mutex_unlock(&ctx->uring_lock);
 328                 if (ret != -EALREADY)
 329                         break;
 330
 331                 ret = io_run_task_work_sig(ctx);
 332                 if (ret < 0)
 333                         break;
 334                 ret = schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS);
 335                 if (!ret) {
 336                         ret = -ETIME;
 337                         break;
 338                 }
 339                 mutex_lock(&ctx->uring_lock);
 340         } while (1);
 341
 342         finish_wait(&ctx->cq_wait, &wait);
 343         mutex_lock(&ctx->uring_lock);
 344
 345         if (ret == -ENOENT || ret > 0)
 346                 ret = 0;
 347 out:
 348         if (file)
 349                 fput(file);
 350         return ret;
 351 }