fs/fuse/ioctl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2017 Red Hat, Inc.
   4  */
   5
   6 #include "fuse_i.h"
   7
   8 #include <linux/uio.h>
   9 #include <linux/compat.h>
  10 #include <linux/fileattr.h>
  11 #include <linux/fsverity.h>
  12
  13 static ssize_t fuse_send_ioctl(struct fuse_mount *fm, struct fuse_args *args,
  14                                struct fuse_ioctl_out *outarg)
  15 {
  16         ssize_t ret;
  17
  18         args->out_args[0].size = sizeof(*outarg);
  19         args->out_args[0].value = outarg;
  20
  21         ret = fuse_simple_request(fm, args);
  22
  23         /* Translate ENOSYS, which shouldn't be returned from fs */
  24         if (ret == -ENOSYS)
  25                 ret = -ENOTTY;
  26
  27         if (ret >= 0 && outarg->result == -ENOSYS)
  28                 outarg->result = -ENOTTY;
  29
  30         return ret;
  31 }
  32
  33 /*
  34  * CUSE servers compiled on 32bit broke on 64bit kernels because the
  35  * ABI was defined to be 'struct iovec' which is different on 32bit
  36  * and 64bit.  Fortunately we can determine which structure the server
  37  * used from the size of the reply.
  38  */
  39 static int fuse_copy_ioctl_iovec_old(struct iovec *dst, void *src,
  40                                      size_t transferred, unsigned count,
  41                                      bool is_compat)
  42 {
  43 #ifdef CONFIG_COMPAT
  44         if (count * sizeof(struct compat_iovec) == transferred) {
  45                 struct compat_iovec *ciov = src;
  46                 unsigned i;
  47
  48                 /*
  49                  * With this interface a 32bit server cannot support
  50                  * non-compat (i.e. ones coming from 64bit apps) ioctl
  51                  * requests
  52                  */
  53                 if (!is_compat)
  54                         return -EINVAL;
  55
  56                 for (i = 0; i < count; i++) {
  57                         dst[i].iov_base = compat_ptr(ciov[i].iov_base);
  58                         dst[i].iov_len = ciov[i].iov_len;
  59                 }
  60                 return 0;
  61         }
  62 #endif
  63
  64         if (count * sizeof(struct iovec) != transferred)
  65                 return -EIO;
  66
  67         memcpy(dst, src, transferred);
  68         return 0;
  69 }
  70
  71 /* Make sure iov_length() won't overflow */
  72 static int fuse_verify_ioctl_iov(struct fuse_conn *fc, struct iovec *iov,
  73                                  size_t count)
  74 {
  75         size_t n;
  76         u32 max = fc->max_pages << PAGE_SHIFT;
  77
  78         for (n = 0; n < count; n++, iov++) {
  79                 if (iov->iov_len > (size_t) max)
  80                         return -ENOMEM;
  81                 max -= iov->iov_len;
  82         }
  83         return 0;
  84 }
  85
  86 static int fuse_copy_ioctl_iovec(struct fuse_conn *fc, struct iovec *dst,
  87                                  void *src, size_t transferred, unsigned count,
  88                                  bool is_compat)
  89 {
  90         unsigned i;
  91         struct fuse_ioctl_iovec *fiov = src;
  92
  93         if (fc->minor < 16) {
  94                 return fuse_copy_ioctl_iovec_old(dst, src, transferred,
  95                                                  count, is_compat);
  96         }
  97
  98         if (count * sizeof(struct fuse_ioctl_iovec) != transferred)
  99                 return -EIO;
 100
 101         for (i = 0; i < count; i++) {
 102                 /* Did the server supply an inappropriate value? */
 103                 if (fiov[i].base != (unsigned long) fiov[i].base ||
 104                     fiov[i].len != (unsigned long) fiov[i].len)
 105                         return -EIO;
 106
 107                 dst[i].iov_base = (void __user *) (unsigned long) fiov[i].base;
 108                 dst[i].iov_len = (size_t) fiov[i].len;
 109
 110 #ifdef CONFIG_COMPAT
 111                 if (is_compat &&
 112                     (ptr_to_compat(dst[i].iov_base) != fiov[i].base ||
 113                      (compat_size_t) dst[i].iov_len != fiov[i].len))
 114                         return -EIO;
 115 #endif
 116         }
 117
 118         return 0;
 119 }
 120
 121 /* For fs-verity, determine iov lengths from input */
 122 static int fuse_setup_measure_verity(unsigned long arg, struct iovec *iov)
 123 {
 124         __u16 digest_size;
 125         struct fsverity_digest __user *uarg = (void __user *)arg;
 126
 127         if (copy_from_user(&digest_size, &uarg->digest_size, sizeof(digest_size)))
 128                 return -EFAULT;
 129
 130         if (digest_size > SIZE_MAX - sizeof(struct fsverity_digest))
 131                 return -EINVAL;
 132
 133         iov->iov_len = sizeof(struct fsverity_digest) + digest_size;
 134
 135         return 0;
 136 }
 137
 138 static int fuse_setup_enable_verity(unsigned long arg, struct iovec *iov,
 139                                     unsigned int *in_iovs)
 140 {
 141         struct fsverity_enable_arg enable;
 142         struct fsverity_enable_arg __user *uarg = (void __user *)arg;
 143         const __u32 max_buffer_len = FUSE_MAX_MAX_PAGES * PAGE_SIZE;
 144
 145         if (copy_from_user(&enable, uarg, sizeof(enable)))
 146                 return -EFAULT;
 147
 148         if (enable.salt_size > max_buffer_len || enable.sig_size > max_buffer_len)
 149                 return -ENOMEM;
 150
 151         if (enable.salt_size > 0) {
 152                 iov++;
 153                 (*in_iovs)++;
 154
 155                 iov->iov_base = u64_to_user_ptr(enable.salt_ptr);
 156                 iov->iov_len = enable.salt_size;
 157         }
 158
 159         if (enable.sig_size > 0) {
 160                 iov++;
 161                 (*in_iovs)++;
 162
 163                 iov->iov_base = u64_to_user_ptr(enable.sig_ptr);
 164                 iov->iov_len = enable.sig_size;
 165         }
 166         return 0;
 167 }
 168
 169 /*
 170  * For ioctls, there is no generic way to determine how much memory
 171  * needs to be read and/or written.  Furthermore, ioctls are allowed
 172  * to dereference the passed pointer, so the parameter requires deep
 173  * copying but FUSE has no idea whatsoever about what to copy in or
 174  * out.
 175  *
 176  * This is solved by allowing FUSE server to retry ioctl with
 177  * necessary in/out iovecs.  Let's assume the ioctl implementation
 178  * needs to read in the following structure.
 179  *
 180  * struct a {
 181  *      char    *buf;
 182  *      size_t  buflen;
 183  * }
 184  *
 185  * On the first callout to FUSE server, inarg->in_size and
 186  * inarg->out_size will be NULL; then, the server completes the ioctl
 187  * with FUSE_IOCTL_RETRY set in out->flags, out->in_iovs set to 1 and
 188  * the actual iov array to
 189  *
 190  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a) } }
 191  *
 192  * which tells FUSE to copy in the requested area and retry the ioctl.
 193  * On the second round, the server has access to the structure and
 194  * from that it can tell what to look for next, so on the invocation,
 195  * it sets FUSE_IOCTL_RETRY, out->in_iovs to 2 and iov array to
 196  *
 197  * { { .iov_base = inarg.arg,   .iov_len = sizeof(struct a)     },
 198  *   { .iov_base = a.buf,       .iov_len = a.buflen             } }
 199  *
 200  * FUSE will copy both struct a and the pointed buffer from the
 201  * process doing the ioctl and retry ioctl with both struct a and the
 202  * buffer.
 203  *
 204  * This time, FUSE server has everything it needs and completes ioctl
 205  * without FUSE_IOCTL_RETRY which finishes the ioctl call.
 206  *
 207  * Copying data out works the same way.
 208  *
 209  * Note that if FUSE_IOCTL_UNRESTRICTED is clear, the kernel
 210  * automatically initializes in and out iovs by decoding @cmd with
 211  * _IOC_* macros and the server is not allowed to request RETRY.  This
 212  * limits ioctl data transfers to well-formed ioctls and is the forced
 213  * behavior for all FUSE servers.
 214  */
 215 long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
 216                    unsigned int flags)
 217 {
 218         struct fuse_file *ff = file->private_data;
 219         struct fuse_mount *fm = ff->fm;
 220         struct fuse_ioctl_in inarg = {
 221                 .fh = ff->fh,
 222                 .cmd = cmd,
 223                 .arg = arg,
 224                 .flags = flags
 225         };
 226         struct fuse_ioctl_out outarg;
 227         struct iovec *iov_page = NULL;
 228         struct iovec *in_iov = NULL, *out_iov = NULL;
 229         unsigned int in_iovs = 0, out_iovs = 0, max_pages;
 230         size_t in_size, out_size, c;
 231         ssize_t transferred;
 232         int err, i;
 233         struct iov_iter ii;
 234         struct fuse_args_pages ap = {};
 235
 236 #if BITS_PER_LONG == 32
 237         inarg.flags |= FUSE_IOCTL_32BIT;
 238 #else
 239         if (flags & FUSE_IOCTL_COMPAT) {
 240                 inarg.flags |= FUSE_IOCTL_32BIT;
 241 #ifdef CONFIG_X86_X32_ABI
 242                 if (in_x32_syscall())
 243                         inarg.flags |= FUSE_IOCTL_COMPAT_X32;
 244 #endif
 245         }
 246 #endif
 247
 248         /* assume all the iovs returned by client always fits in a page */
 249         BUILD_BUG_ON(sizeof(struct fuse_ioctl_iovec) * FUSE_IOCTL_MAX_IOV > PAGE_SIZE);
 250
 251         err = -ENOMEM;
 252         ap.pages = fuse_pages_alloc(fm->fc->max_pages, GFP_KERNEL, &ap.descs);
 253         iov_page = (struct iovec *) __get_free_page(GFP_KERNEL);
 254         if (!ap.pages || !iov_page)
 255                 goto out;
 256
 257         fuse_page_descs_length_init(ap.descs, 0, fm->fc->max_pages);
 258
 259         /*
 260          * If restricted, initialize IO parameters as encoded in @cmd.
 261          * RETRY from server is not allowed.
 262          */
 263         if (!(flags & FUSE_IOCTL_UNRESTRICTED)) {
 264                 struct iovec *iov = iov_page;
 265
 266                 iov->iov_base = (void __user *)arg;
 267                 iov->iov_len = _IOC_SIZE(cmd);
 268
 269                 if (_IOC_DIR(cmd) & _IOC_WRITE) {
 270                         in_iov = iov;
 271                         in_iovs = 1;
 272                 }
 273
 274                 if (_IOC_DIR(cmd) & _IOC_READ) {
 275                         out_iov = iov;
 276                         out_iovs = 1;
 277                 }
 278
 279                 err = 0;
 280                 switch (cmd) {
 281                 case FS_IOC_MEASURE_VERITY:
 282                         err = fuse_setup_measure_verity(arg, iov);
 283                         break;
 284                 case FS_IOC_ENABLE_VERITY:
 285                         err = fuse_setup_enable_verity(arg, iov, &in_iovs);
 286                         break;
 287                 }
 288                 if (err)
 289                         goto out;
 290         }
 291
 292  retry:
 293         inarg.in_size = in_size = iov_length(in_iov, in_iovs);
 294         inarg.out_size = out_size = iov_length(out_iov, out_iovs);
 295
 296         /*
 297          * Out data can be used either for actual out data or iovs,
 298          * make sure there always is at least one page.
 299          */
 300         out_size = max_t(size_t, out_size, PAGE_SIZE);
 301         max_pages = DIV_ROUND_UP(max(in_size, out_size), PAGE_SIZE);
 302
 303         /* make sure there are enough buffer pages and init request with them */
 304         err = -ENOMEM;
 305         if (max_pages > fm->fc->max_pages)
 306                 goto out;
 307         while (ap.num_pages < max_pages) {
 308                 ap.pages[ap.num_pages] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 309                 if (!ap.pages[ap.num_pages])
 310                         goto out;
 311                 ap.num_pages++;
 312         }
 313
 314
 315         /* okay, let's send it to the client */
 316         ap.args.opcode = FUSE_IOCTL;
 317         ap.args.nodeid = ff->nodeid;
 318         ap.args.in_numargs = 1;
 319         ap.args.in_args[0].size = sizeof(inarg);
 320         ap.args.in_args[0].value = &inarg;
 321         if (in_size) {
 322                 ap.args.in_numargs++;
 323                 ap.args.in_args[1].size = in_size;
 324                 ap.args.in_pages = true;
 325
 326                 err = -EFAULT;
 327                 iov_iter_init(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
 328                 for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 329                         c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 330                         if (c != PAGE_SIZE && iov_iter_count(&ii))
 331                                 goto out;
 332                 }
 333         }
 334
 335         ap.args.out_numargs = 2;
 336         ap.args.out_args[1].size = out_size;
 337         ap.args.out_pages = true;
 338         ap.args.out_argvar = true;
 339
 340         transferred = fuse_send_ioctl(fm, &ap.args, &outarg);
 341         err = transferred;
 342         if (transferred < 0)
 343                 goto out;
 344
 345         /* did it ask for retry? */
 346         if (outarg.flags & FUSE_IOCTL_RETRY) {
 347                 void *vaddr;
 348
 349                 /* no retry if in restricted mode */
 350                 err = -EIO;
 351                 if (!(flags & FUSE_IOCTL_UNRESTRICTED))
 352                         goto out;
 353
 354                 in_iovs = outarg.in_iovs;
 355                 out_iovs = outarg.out_iovs;
 356
 357                 /*
 358                  * Make sure things are in boundary, separate checks
 359                  * are to protect against overflow.
 360                  */
 361                 err = -ENOMEM;
 362                 if (in_iovs > FUSE_IOCTL_MAX_IOV ||
 363                     out_iovs > FUSE_IOCTL_MAX_IOV ||
 364                     in_iovs + out_iovs > FUSE_IOCTL_MAX_IOV)
 365                         goto out;
 366
 367                 vaddr = kmap_local_page(ap.pages[0]);
 368                 err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
 369                                             transferred, in_iovs + out_iovs,
 370                                             (flags & FUSE_IOCTL_COMPAT) != 0);
 371                 kunmap_local(vaddr);
 372                 if (err)
 373                         goto out;
 374
 375                 in_iov = iov_page;
 376                 out_iov = in_iov + in_iovs;
 377
 378                 err = fuse_verify_ioctl_iov(fm->fc, in_iov, in_iovs);
 379                 if (err)
 380                         goto out;
 381
 382                 err = fuse_verify_ioctl_iov(fm->fc, out_iov, out_iovs);
 383                 if (err)
 384                         goto out;
 385
 386                 goto retry;
 387         }
 388
 389         err = -EIO;
 390         if (transferred > inarg.out_size)
 391                 goto out;
 392
 393         err = -EFAULT;
 394         iov_iter_init(&ii, ITER_DEST, out_iov, out_iovs, transferred);
 395         for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
 396                 c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
 397                 if (c != PAGE_SIZE && iov_iter_count(&ii))
 398                         goto out;
 399         }
 400         err = 0;
 401  out:
 402         free_page((unsigned long) iov_page);
 403         while (ap.num_pages)
 404                 __free_page(ap.pages[--ap.num_pages]);
 405         kfree(ap.pages);
 406
 407         return err ? err : outarg.result;
 408 }
 409 EXPORT_SYMBOL_GPL(fuse_do_ioctl);
 410
 411 long fuse_ioctl_common(struct file *file, unsigned int cmd,
 412                        unsigned long arg, unsigned int flags)
 413 {
 414         struct inode *inode = file_inode(file);
 415         struct fuse_conn *fc = get_fuse_conn(inode);
 416
 417         if (!fuse_allow_current_process(fc))
 418                 return -EACCES;
 419
 420         if (fuse_is_bad(inode))
 421                 return -EIO;
 422
 423         return fuse_do_ioctl(file, cmd, arg, flags);
 424 }
 425
 426 long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 427 {
 428         return fuse_ioctl_common(file, cmd, arg, 0);
 429 }
 430
 431 long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
 432                             unsigned long arg)
 433 {
 434         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_COMPAT);
 435 }
 436
 437 static int fuse_priv_ioctl(struct inode *inode, struct fuse_file *ff,
 438                            unsigned int cmd, void *ptr, size_t size)
 439 {
 440         struct fuse_mount *fm = ff->fm;
 441         struct fuse_ioctl_in inarg;
 442         struct fuse_ioctl_out outarg;
 443         FUSE_ARGS(args);
 444         int err;
 445
 446         memset(&inarg, 0, sizeof(inarg));
 447         inarg.fh = ff->fh;
 448         inarg.cmd = cmd;
 449
 450 #if BITS_PER_LONG == 32
 451         inarg.flags |= FUSE_IOCTL_32BIT;
 452 #endif
 453         if (S_ISDIR(inode->i_mode))
 454                 inarg.flags |= FUSE_IOCTL_DIR;
 455
 456         if (_IOC_DIR(cmd) & _IOC_READ)
 457                 inarg.out_size = size;
 458         if (_IOC_DIR(cmd) & _IOC_WRITE)
 459                 inarg.in_size = size;
 460
 461         args.opcode = FUSE_IOCTL;
 462         args.nodeid = ff->nodeid;
 463         args.in_numargs = 2;
 464         args.in_args[0].size = sizeof(inarg);
 465         args.in_args[0].value = &inarg;
 466         args.in_args[1].size = inarg.in_size;
 467         args.in_args[1].value = ptr;
 468         args.out_numargs = 2;
 469         args.out_args[1].size = inarg.out_size;
 470         args.out_args[1].value = ptr;
 471
 472         err = fuse_send_ioctl(fm, &args, &outarg);
 473         if (!err) {
 474                 if (outarg.result < 0)
 475                         err = outarg.result;
 476                 else if (outarg.flags & FUSE_IOCTL_RETRY)
 477                         err = -EIO;
 478         }
 479         return err;
 480 }
 481
 482 static struct fuse_file *fuse_priv_ioctl_prepare(struct inode *inode)
 483 {
 484         struct fuse_mount *fm = get_fuse_mount(inode);
 485         bool isdir = S_ISDIR(inode->i_mode);
 486
 487         if (!fuse_allow_current_process(fm->fc))
 488                 return ERR_PTR(-EACCES);
 489
 490         if (fuse_is_bad(inode))
 491                 return ERR_PTR(-EIO);
 492
 493         if (!S_ISREG(inode->i_mode) && !isdir)
 494                 return ERR_PTR(-ENOTTY);
 495
 496         return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
 497 }
 498
 499 static void fuse_priv_ioctl_cleanup(struct inode *inode, struct fuse_file *ff)
 500 {
 501         fuse_file_release(inode, ff, O_RDONLY, NULL, S_ISDIR(inode->i_mode));
 502 }
 503
 504 int fuse_fileattr_get(struct dentry *dentry, struct fileattr *fa)
 505 {
 506         struct inode *inode = d_inode(dentry);
 507         struct fuse_file *ff;
 508         unsigned int flags;
 509         struct fsxattr xfa;
 510         int err;
 511
 512         ff = fuse_priv_ioctl_prepare(inode);
 513         if (IS_ERR(ff))
 514                 return PTR_ERR(ff);
 515
 516         if (fa->flags_valid) {
 517                 err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
 518                                       &flags, sizeof(flags));
 519                 if (err)
 520                         goto cleanup;
 521
 522                 fileattr_fill_flags(fa, flags);
 523         } else {
 524                 err = fuse_priv_ioctl(inode, ff, FS_IOC_FSGETXATTR,
 525                                       &xfa, sizeof(xfa));
 526                 if (err)
 527                         goto cleanup;
 528
 529                 fileattr_fill_xflags(fa, xfa.fsx_xflags);
 530                 fa->fsx_extsize = xfa.fsx_extsize;
 531                 fa->fsx_nextents = xfa.fsx_nextents;
 532                 fa->fsx_projid = xfa.fsx_projid;
 533                 fa->fsx_cowextsize = xfa.fsx_cowextsize;
 534         }
 535 cleanup:
 536         fuse_priv_ioctl_cleanup(inode, ff);
 537
 538         return err;
 539 }
 540
 541 int fuse_fileattr_set(struct mnt_idmap *idmap,
 542                       struct dentry *dentry, struct fileattr *fa)
 543 {
 544         struct inode *inode = d_inode(dentry);
 545         struct fuse_file *ff;
 546         unsigned int flags = fa->flags;
 547         struct fsxattr xfa;
 548         int err;
 549
 550         ff = fuse_priv_ioctl_prepare(inode);
 551         if (IS_ERR(ff))
 552                 return PTR_ERR(ff);
 553
 554         if (fa->flags_valid) {
 555                 err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
 556                                       &flags, sizeof(flags));
 557                 if (err)
 558                         goto cleanup;
 559         } else {
 560                 memset(&xfa, 0, sizeof(xfa));
 561                 xfa.fsx_xflags = fa->fsx_xflags;
 562                 xfa.fsx_extsize = fa->fsx_extsize;
 563                 xfa.fsx_nextents = fa->fsx_nextents;
 564                 xfa.fsx_projid = fa->fsx_projid;
 565                 xfa.fsx_cowextsize = fa->fsx_cowextsize;
 566
 567                 err = fuse_priv_ioctl(inode, ff, FS_IOC_FSSETXATTR,
 568                                       &xfa, sizeof(xfa));
 569         }
 570
 571 cleanup:
 572         fuse_priv_ioctl_cleanup(inode, ff);
 573
 574         return err;
 575 }