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
12static 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 */
38static 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(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 */
71static 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
85static 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(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 */
167long 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(fm->fc->max_pages, GFP_KERNEL, &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(ap.descs, 0, 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(in_iov, in_iovs);
234	inarg.out_size = out_size = iov_length(out_iov, 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(&ii, ITER_SOURCE, in_iov, in_iovs, in_size);
268		for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
269			c = copy_page_from_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
270			if (c != PAGE_SIZE && iov_iter_count(&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, &ap.args, &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(ap.pages[0]);
308		err = fuse_copy_ioctl_iovec(fm->fc, iov_page, vaddr,
309					    transferred, in_iovs + out_iovs,
310					    (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(fm->fc, in_iov, in_iovs);
319		if (err)
320			goto out;
321
322		err = fuse_verify_ioctl_iov(fm->fc, out_iov, 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(&ii, ITER_DEST, out_iov, out_iovs, transferred);
335	for (i = 0; iov_iter_count(&ii) && !WARN_ON(i >= ap.num_pages); i++) {
336		c = copy_page_to_iter(ap.pages[i], 0, PAGE_SIZE, &ii);
337		if (c != PAGE_SIZE && iov_iter_count(&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(ap.pages);
346
347	return err ? err : outarg.result;
348}
349EXPORT_SYMBOL_GPL(fuse_do_ioctl);
350
351long fuse_ioctl_common(struct file *file, unsigned int cmd,
352		       unsigned long arg, unsigned int flags)
353{
354	struct inode *inode = file_inode(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
366long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
367{
368	return fuse_ioctl_common(file, cmd, arg, 0);
369}
370
371long 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
377static 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, &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
422static 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(fm->fc))
428		return ERR_PTR(-EACCES);
429
430	if (fuse_is_bad(inode))
431		return ERR_PTR(-EIO);
432
433	if (!S_ISREG(inode->i_mode) && !isdir)
434		return ERR_PTR(-ENOTTY);
435
436	return fuse_file_open(fm, get_node_id(inode), O_RDONLY, isdir);
437}
438
439static 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
444int 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(ff))
454		return PTR_ERR(ff);
455
456	if (fa->flags_valid) {
457		err = fuse_priv_ioctl(inode, ff, FS_IOC_GETFLAGS,
458				      &flags, 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				      &xfa, sizeof(xfa));
466		if (err)
467			goto cleanup;
468
469		fileattr_fill_xflags(fa, 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	}
475cleanup:
476	fuse_priv_ioctl_cleanup(inode, ff);
477
478	return err;
479}
480
481int 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(ff))
492		return PTR_ERR(ff);
493
494	if (fa->flags_valid) {
495		err = fuse_priv_ioctl(inode, ff, FS_IOC_SETFLAGS,
496				      &flags, 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				      &xfa, sizeof(xfa));
509	}
510
511cleanup:
512	fuse_priv_ioctl_cleanup(inode, ff);
513
514	return err;
515}
516