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