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->tctx;
 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 static int __io_sync_cancel(struct io_uring_task *tctx,
 236                             struct io_cancel_data *cd, int fd)
 237 {
 238         struct io_ring_ctx *ctx = cd->ctx;
 239
 240         /* fixed must be grabbed every time since we drop the uring_lock */
 241         if ((cd->flags & IORING_ASYNC_CANCEL_FD) &&
 242             (cd->flags & IORING_ASYNC_CANCEL_FD_FIXED)) {
 243                 struct io_rsrc_node *node;
 244
 245                 node = io_rsrc_node_lookup(&ctx->file_table.data, fd);
 246                 if (unlikely(!node))
 247                         return -EBADF;
 248                 cd->file = io_slot_file(node);
 249                 if (!cd->file)
 250                         return -EBADF;
 251         }
 252
 253         return __io_async_cancel(cd, tctx, 0);
 254 }
 255
 256 int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg)
 257         __must_hold(&ctx->uring_lock)
 258 {
 259         struct io_cancel_data cd = {
 260                 .ctx    = ctx,
 261                 .seq    = atomic_inc_return(&ctx->cancel_seq),
 262         };
 263         ktime_t timeout = KTIME_MAX;
 264         struct io_uring_sync_cancel_reg sc;
 265         struct file *file = NULL;
 266         DEFINE_WAIT(wait);
 267         int ret, i;
 268
 269         if (copy_from_user(&sc, arg, sizeof(sc)))
 270                 return -EFAULT;
 271         if (sc.flags & ~CANCEL_FLAGS)
 272                 return -EINVAL;
 273         for (i = 0; i < ARRAY_SIZE(sc.pad); i++)
 274                 if (sc.pad[i])
 275                         return -EINVAL;
 276         for (i = 0; i < ARRAY_SIZE(sc.pad2); i++)
 277                 if (sc.pad2[i])
 278                         return -EINVAL;
 279
 280         cd.data = sc.addr;
 281         cd.flags = sc.flags;
 282         cd.opcode = sc.opcode;
 283
 284         /* we can grab a normal file descriptor upfront */
 285         if ((cd.flags & IORING_ASYNC_CANCEL_FD) &&
 286            !(cd.flags & IORING_ASYNC_CANCEL_FD_FIXED)) {
 287                 file = fget(sc.fd);
 288                 if (!file)
 289                         return -EBADF;
 290                 cd.file = file;
 291         }
 292
 293         ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);
 294
 295         /* found something, done! */
 296         if (ret != -EALREADY)
 297                 goto out;
 298
 299         if (sc.timeout.tv_sec != -1UL || sc.timeout.tv_nsec != -1UL) {
 300                 struct timespec64 ts = {
 301                         .tv_sec         = sc.timeout.tv_sec,
 302                         .tv_nsec        = sc.timeout.tv_nsec
 303                 };
 304
 305                 timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
 306         }
 307
 308         /*
 309          * Keep looking until we get -ENOENT. we'll get woken everytime
 310          * every time a request completes and will retry the cancelation.
 311          */
 312         do {
 313                 cd.seq = atomic_inc_return(&ctx->cancel_seq);
 314
 315                 prepare_to_wait(&ctx->cq_wait, &wait, TASK_INTERRUPTIBLE);
 316
 317                 ret = __io_sync_cancel(current->io_uring, &cd, sc.fd);
 318
 319                 mutex_unlock(&ctx->uring_lock);
 320                 if (ret != -EALREADY)
 321                         break;
 322
 323                 ret = io_run_task_work_sig(ctx);
 324                 if (ret < 0)
 325                         break;
 326                 ret = schedule_hrtimeout(&timeout, HRTIMER_MODE_ABS);
 327                 if (!ret) {
 328                         ret = -ETIME;
 329                         break;
 330                 }
 331                 mutex_lock(&ctx->uring_lock);
 332         } while (1);
 333
 334         finish_wait(&ctx->cq_wait, &wait);
 335         mutex_lock(&ctx->uring_lock);
 336
 337         if (ret == -ENOENT || ret > 0)
 338                 ret = 0;
 339 out:
 340         if (file)
 341                 fput(file);
 342         return ret;
 343 }