Commit | Line | Data |
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328970de | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
fa60ce2c | 2 | /* |
7063fbf2 JB |
3 | * file.c - operations for regular (text) files. |
4 | * | |
7063fbf2 JB |
5 | * Based on sysfs: |
6 | * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel | |
7 | * | |
8 | * configfs Copyright (C) 2005 Oracle. All rights reserved. | |
9 | */ | |
10 | ||
11 | #include <linux/fs.h> | |
12 | #include <linux/module.h> | |
7063fbf2 | 13 | #include <linux/slab.h> |
6d748924 | 14 | #include <linux/mutex.h> |
03607ace | 15 | #include <linux/vmalloc.h> |
7c0f6ba6 | 16 | #include <linux/uaccess.h> |
7fe1e79b | 17 | #include <linux/uio.h> |
7063fbf2 JB |
18 | #include <linux/configfs.h> |
19 | #include "configfs_internal.h" | |
20 | ||
b23cdde4 JB |
21 | /* |
22 | * A simple attribute can only be 4096 characters. Why 4k? Because the | |
23 | * original code limited it to PAGE_SIZE. That's a bad idea, though, | |
24 | * because an attribute of 16k on ia64 won't work on x86. So we limit to | |
25 | * 4k, our minimum common page size. | |
26 | */ | |
27 | #define SIMPLE_ATTR_SIZE 4096 | |
7063fbf2 JB |
28 | |
29 | struct configfs_buffer { | |
30 | size_t count; | |
31 | loff_t pos; | |
32 | char * page; | |
33 | struct configfs_item_operations * ops; | |
6d748924 | 34 | struct mutex mutex; |
7063fbf2 | 35 | int needs_read_fill; |
03607ace PA |
36 | bool read_in_progress; |
37 | bool write_in_progress; | |
38 | char *bin_buffer; | |
39 | int bin_buffer_size; | |
ff4dd081 AV |
40 | int cb_max_size; |
41 | struct config_item *item; | |
42 | struct module *owner; | |
43 | union { | |
44 | struct configfs_attribute *attr; | |
45 | struct configfs_bin_attribute *bin_attr; | |
46 | }; | |
7063fbf2 JB |
47 | }; |
48 | ||
b0841eef AV |
49 | static inline struct configfs_fragment *to_frag(struct file *file) |
50 | { | |
51 | struct configfs_dirent *sd = file->f_path.dentry->d_fsdata; | |
52 | ||
53 | return sd->s_frag; | |
54 | } | |
7063fbf2 | 55 | |
b0841eef | 56 | static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer) |
7063fbf2 | 57 | { |
b0841eef AV |
58 | struct configfs_fragment *frag = to_frag(file); |
59 | ssize_t count = -ENOENT; | |
7063fbf2 JB |
60 | |
61 | if (!buffer->page) | |
62 | buffer->page = (char *) get_zeroed_page(GFP_KERNEL); | |
63 | if (!buffer->page) | |
64 | return -ENOMEM; | |
65 | ||
b0841eef AV |
66 | down_read(&frag->frag_sem); |
67 | if (!frag->frag_dead) | |
68 | count = buffer->attr->show(buffer->item, buffer->page); | |
69 | up_read(&frag->frag_sem); | |
70 | ||
ff4dd081 AV |
71 | if (count < 0) |
72 | return count; | |
73 | if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE)) | |
74 | return -EIO; | |
ff4dd081 AV |
75 | buffer->needs_read_fill = 0; |
76 | buffer->count = count; | |
77 | return 0; | |
7063fbf2 JB |
78 | } |
79 | ||
7fe1e79b | 80 | static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to) |
7063fbf2 | 81 | { |
7fe1e79b | 82 | struct file *file = iocb->ki_filp; |
ff4dd081 | 83 | struct configfs_buffer *buffer = file->private_data; |
7063fbf2 JB |
84 | ssize_t retval = 0; |
85 | ||
6d748924 | 86 | mutex_lock(&buffer->mutex); |
7063fbf2 | 87 | if (buffer->needs_read_fill) { |
b0841eef | 88 | retval = fill_read_buffer(file, buffer); |
ff4dd081 | 89 | if (retval) |
7063fbf2 JB |
90 | goto out; |
91 | } | |
7fe1e79b BVA |
92 | pr_debug("%s: count = %zd, pos = %lld, buf = %s\n", |
93 | __func__, iov_iter_count(to), iocb->ki_pos, buffer->page); | |
420405ec BVA |
94 | if (iocb->ki_pos >= buffer->count) |
95 | goto out; | |
96 | retval = copy_to_iter(buffer->page + iocb->ki_pos, | |
97 | buffer->count - iocb->ki_pos, to); | |
7fe1e79b BVA |
98 | iocb->ki_pos += retval; |
99 | if (retval == 0) | |
100 | retval = -EFAULT; | |
7063fbf2 | 101 | out: |
6d748924 | 102 | mutex_unlock(&buffer->mutex); |
7063fbf2 JB |
103 | return retval; |
104 | } | |
105 | ||
7fe1e79b | 106 | static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to) |
03607ace | 107 | { |
7fe1e79b | 108 | struct file *file = iocb->ki_filp; |
b0841eef | 109 | struct configfs_fragment *frag = to_frag(file); |
03607ace | 110 | struct configfs_buffer *buffer = file->private_data; |
03607ace | 111 | ssize_t retval = 0; |
7fe1e79b | 112 | ssize_t len; |
03607ace PA |
113 | |
114 | mutex_lock(&buffer->mutex); | |
115 | ||
116 | /* we don't support switching read/write modes */ | |
117 | if (buffer->write_in_progress) { | |
118 | retval = -ETXTBSY; | |
119 | goto out; | |
120 | } | |
3f6928c3 | 121 | buffer->read_in_progress = true; |
03607ace PA |
122 | |
123 | if (buffer->needs_read_fill) { | |
124 | /* perform first read with buf == NULL to get extent */ | |
b0841eef AV |
125 | down_read(&frag->frag_sem); |
126 | if (!frag->frag_dead) | |
127 | len = buffer->bin_attr->read(buffer->item, NULL, 0); | |
128 | else | |
129 | len = -ENOENT; | |
130 | up_read(&frag->frag_sem); | |
03607ace PA |
131 | if (len <= 0) { |
132 | retval = len; | |
133 | goto out; | |
134 | } | |
135 | ||
136 | /* do not exceed the maximum value */ | |
ff4dd081 | 137 | if (buffer->cb_max_size && len > buffer->cb_max_size) { |
03607ace PA |
138 | retval = -EFBIG; |
139 | goto out; | |
140 | } | |
141 | ||
142 | buffer->bin_buffer = vmalloc(len); | |
143 | if (buffer->bin_buffer == NULL) { | |
144 | retval = -ENOMEM; | |
145 | goto out; | |
146 | } | |
147 | buffer->bin_buffer_size = len; | |
148 | ||
149 | /* perform second read to fill buffer */ | |
b0841eef AV |
150 | down_read(&frag->frag_sem); |
151 | if (!frag->frag_dead) | |
152 | len = buffer->bin_attr->read(buffer->item, | |
153 | buffer->bin_buffer, len); | |
154 | else | |
155 | len = -ENOENT; | |
156 | up_read(&frag->frag_sem); | |
03607ace PA |
157 | if (len < 0) { |
158 | retval = len; | |
159 | vfree(buffer->bin_buffer); | |
160 | buffer->bin_buffer_size = 0; | |
161 | buffer->bin_buffer = NULL; | |
162 | goto out; | |
163 | } | |
164 | ||
165 | buffer->needs_read_fill = 0; | |
166 | } | |
167 | ||
420405ec BVA |
168 | if (iocb->ki_pos >= buffer->bin_buffer_size) |
169 | goto out; | |
170 | retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos, | |
171 | buffer->bin_buffer_size - iocb->ki_pos, to); | |
7fe1e79b BVA |
172 | iocb->ki_pos += retval; |
173 | if (retval == 0) | |
174 | retval = -EFAULT; | |
03607ace PA |
175 | out: |
176 | mutex_unlock(&buffer->mutex); | |
177 | return retval; | |
178 | } | |
179 | ||
769f5267 BVA |
180 | /* Fill @buffer with data coming from @from. */ |
181 | static int fill_write_buffer(struct configfs_buffer *buffer, | |
7fe1e79b | 182 | struct iov_iter *from) |
7063fbf2 | 183 | { |
7fe1e79b | 184 | int copied; |
7063fbf2 JB |
185 | |
186 | if (!buffer->page) | |
ff05d1c4 | 187 | buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0); |
7063fbf2 JB |
188 | if (!buffer->page) |
189 | return -ENOMEM; | |
190 | ||
769f5267 | 191 | copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from); |
7063fbf2 | 192 | buffer->needs_read_fill = 1; |
ff05d1c4 JB |
193 | /* if buf is assumed to contain a string, terminate it by \0, |
194 | * so e.g. sscanf() can scan the string easily */ | |
769f5267 | 195 | buffer->page[copied] = 0; |
7fe1e79b | 196 | return copied ? : -EFAULT; |
7063fbf2 JB |
197 | } |
198 | ||
7063fbf2 | 199 | static int |
b0841eef | 200 | flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t count) |
7063fbf2 | 201 | { |
b0841eef AV |
202 | struct configfs_fragment *frag = to_frag(file); |
203 | int res = -ENOENT; | |
204 | ||
205 | down_read(&frag->frag_sem); | |
206 | if (!frag->frag_dead) | |
207 | res = buffer->attr->store(buffer->item, buffer->page, count); | |
208 | up_read(&frag->frag_sem); | |
209 | return res; | |
7063fbf2 JB |
210 | } |
211 | ||
212 | ||
44b9a000 CH |
213 | /* |
214 | * There is no easy way for us to know if userspace is only doing a partial | |
215 | * write, so we don't support them. We expect the entire buffer to come on the | |
216 | * first write. | |
217 | * Hint: if you're writing a value, first read the file, modify only the value | |
218 | * you're changing, then write entire buffer back. | |
7063fbf2 | 219 | */ |
7fe1e79b | 220 | static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from) |
7063fbf2 | 221 | { |
7fe1e79b | 222 | struct file *file = iocb->ki_filp; |
ff4dd081 | 223 | struct configfs_buffer *buffer = file->private_data; |
769f5267 | 224 | int len; |
7063fbf2 | 225 | |
6d748924 | 226 | mutex_lock(&buffer->mutex); |
769f5267 | 227 | len = fill_write_buffer(buffer, from); |
3d0f89bb | 228 | if (len > 0) |
b0841eef | 229 | len = flush_write_buffer(file, buffer, len); |
3d0f89bb | 230 | if (len > 0) |
7fe1e79b | 231 | iocb->ki_pos += len; |
6d748924 | 232 | mutex_unlock(&buffer->mutex); |
3d0f89bb | 233 | return len; |
7063fbf2 JB |
234 | } |
235 | ||
7fe1e79b BVA |
236 | static ssize_t configfs_bin_write_iter(struct kiocb *iocb, |
237 | struct iov_iter *from) | |
03607ace | 238 | { |
7fe1e79b | 239 | struct file *file = iocb->ki_filp; |
03607ace | 240 | struct configfs_buffer *buffer = file->private_data; |
03607ace | 241 | void *tbuf = NULL; |
7fe1e79b | 242 | size_t end_offset; |
03607ace PA |
243 | ssize_t len; |
244 | ||
245 | mutex_lock(&buffer->mutex); | |
246 | ||
247 | /* we don't support switching read/write modes */ | |
248 | if (buffer->read_in_progress) { | |
249 | len = -ETXTBSY; | |
250 | goto out; | |
251 | } | |
3f6928c3 | 252 | buffer->write_in_progress = true; |
03607ace PA |
253 | |
254 | /* buffer grows? */ | |
7fe1e79b BVA |
255 | end_offset = iocb->ki_pos + iov_iter_count(from); |
256 | if (end_offset > buffer->bin_buffer_size) { | |
257 | if (buffer->cb_max_size && end_offset > buffer->cb_max_size) { | |
03607ace | 258 | len = -EFBIG; |
42857cf5 | 259 | goto out; |
03607ace PA |
260 | } |
261 | ||
7fe1e79b | 262 | tbuf = vmalloc(end_offset); |
03607ace PA |
263 | if (tbuf == NULL) { |
264 | len = -ENOMEM; | |
265 | goto out; | |
266 | } | |
267 | ||
268 | /* copy old contents */ | |
269 | if (buffer->bin_buffer) { | |
270 | memcpy(tbuf, buffer->bin_buffer, | |
271 | buffer->bin_buffer_size); | |
272 | vfree(buffer->bin_buffer); | |
273 | } | |
274 | ||
275 | /* clear the new area */ | |
276 | memset(tbuf + buffer->bin_buffer_size, 0, | |
7fe1e79b | 277 | end_offset - buffer->bin_buffer_size); |
03607ace | 278 | buffer->bin_buffer = tbuf; |
7fe1e79b | 279 | buffer->bin_buffer_size = end_offset; |
03607ace PA |
280 | } |
281 | ||
420405ec BVA |
282 | len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos, |
283 | buffer->bin_buffer_size - iocb->ki_pos, from); | |
284 | iocb->ki_pos += len; | |
03607ace PA |
285 | out: |
286 | mutex_unlock(&buffer->mutex); | |
7fe1e79b | 287 | return len ? : -EFAULT; |
03607ace PA |
288 | } |
289 | ||
ff4dd081 | 290 | static int __configfs_open_file(struct inode *inode, struct file *file, int type) |
7063fbf2 | 291 | { |
ff4dd081 | 292 | struct dentry *dentry = file->f_path.dentry; |
b0841eef | 293 | struct configfs_fragment *frag = to_frag(file); |
ff4dd081 AV |
294 | struct configfs_attribute *attr; |
295 | struct configfs_buffer *buffer; | |
296 | int error; | |
7063fbf2 | 297 | |
ff4dd081 AV |
298 | error = -ENOMEM; |
299 | buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL); | |
300 | if (!buffer) | |
301 | goto out; | |
7063fbf2 | 302 | |
b0841eef AV |
303 | error = -ENOENT; |
304 | down_read(&frag->frag_sem); | |
305 | if (unlikely(frag->frag_dead)) | |
306 | goto out_free_buffer; | |
307 | ||
ff4dd081 | 308 | error = -EINVAL; |
b0841eef | 309 | buffer->item = to_item(dentry->d_parent); |
ff4dd081 AV |
310 | if (!buffer->item) |
311 | goto out_free_buffer; | |
312 | ||
313 | attr = to_attr(dentry); | |
314 | if (!attr) | |
14fbbc82 | 315 | goto out_free_buffer; |
ff4dd081 AV |
316 | |
317 | if (type & CONFIGFS_ITEM_BIN_ATTR) { | |
318 | buffer->bin_attr = to_bin_attr(dentry); | |
319 | buffer->cb_max_size = buffer->bin_attr->cb_max_size; | |
320 | } else { | |
321 | buffer->attr = attr; | |
322 | } | |
03607ace | 323 | |
ff4dd081 | 324 | buffer->owner = attr->ca_owner; |
7063fbf2 | 325 | /* Grab the module reference for this attribute if we have one */ |
ff4dd081 AV |
326 | error = -ENODEV; |
327 | if (!try_module_get(buffer->owner)) | |
14fbbc82 | 328 | goto out_free_buffer; |
7063fbf2 | 329 | |
ff4dd081 AV |
330 | error = -EACCES; |
331 | if (!buffer->item->ci_type) | |
332 | goto out_put_module; | |
333 | ||
334 | buffer->ops = buffer->item->ci_type->ct_item_ops; | |
7063fbf2 JB |
335 | |
336 | /* File needs write support. | |
337 | * The inode's perms must say it's ok, | |
338 | * and we must have a store method. | |
339 | */ | |
340 | if (file->f_mode & FMODE_WRITE) { | |
03607ace | 341 | if (!(inode->i_mode & S_IWUGO)) |
ff4dd081 | 342 | goto out_put_module; |
03607ace | 343 | if ((type & CONFIGFS_ITEM_ATTR) && !attr->store) |
ff4dd081 AV |
344 | goto out_put_module; |
345 | if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write) | |
346 | goto out_put_module; | |
7063fbf2 JB |
347 | } |
348 | ||
349 | /* File needs read support. | |
350 | * The inode's perms must say it's ok, and we there | |
351 | * must be a show method for it. | |
352 | */ | |
353 | if (file->f_mode & FMODE_READ) { | |
03607ace | 354 | if (!(inode->i_mode & S_IRUGO)) |
ff4dd081 | 355 | goto out_put_module; |
03607ace | 356 | if ((type & CONFIGFS_ITEM_ATTR) && !attr->show) |
ff4dd081 AV |
357 | goto out_put_module; |
358 | if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read) | |
359 | goto out_put_module; | |
7063fbf2 JB |
360 | } |
361 | ||
6d748924 | 362 | mutex_init(&buffer->mutex); |
559c9ac3 | 363 | buffer->needs_read_fill = 1; |
3f6928c3 TM |
364 | buffer->read_in_progress = false; |
365 | buffer->write_in_progress = false; | |
559c9ac3 | 366 | file->private_data = buffer; |
b0841eef | 367 | up_read(&frag->frag_sem); |
ff4dd081 | 368 | return 0; |
7063fbf2 | 369 | |
ff4dd081 AV |
370 | out_put_module: |
371 | module_put(buffer->owner); | |
ff4dd081 | 372 | out_free_buffer: |
b0841eef | 373 | up_read(&frag->frag_sem); |
ff4dd081 AV |
374 | kfree(buffer); |
375 | out: | |
7063fbf2 JB |
376 | return error; |
377 | } | |
378 | ||
03607ace | 379 | static int configfs_release(struct inode *inode, struct file *filp) |
7063fbf2 | 380 | { |
ff4dd081 AV |
381 | struct configfs_buffer *buffer = filp->private_data; |
382 | ||
ff4dd081 AV |
383 | module_put(buffer->owner); |
384 | if (buffer->page) | |
385 | free_page((unsigned long)buffer->page); | |
386 | mutex_destroy(&buffer->mutex); | |
387 | kfree(buffer); | |
7063fbf2 JB |
388 | return 0; |
389 | } | |
390 | ||
03607ace PA |
391 | static int configfs_open_file(struct inode *inode, struct file *filp) |
392 | { | |
ff4dd081 | 393 | return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR); |
03607ace PA |
394 | } |
395 | ||
396 | static int configfs_open_bin_file(struct inode *inode, struct file *filp) | |
397 | { | |
ff4dd081 | 398 | return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR); |
03607ace PA |
399 | } |
400 | ||
ff4dd081 | 401 | static int configfs_release_bin_file(struct inode *inode, struct file *file) |
03607ace | 402 | { |
ff4dd081 | 403 | struct configfs_buffer *buffer = file->private_data; |
03607ace | 404 | |
03607ace | 405 | if (buffer->write_in_progress) { |
b0841eef | 406 | struct configfs_fragment *frag = to_frag(file); |
03607ace | 407 | |
b0841eef AV |
408 | down_read(&frag->frag_sem); |
409 | if (!frag->frag_dead) { | |
410 | /* result of ->release() is ignored */ | |
411 | buffer->bin_attr->write(buffer->item, | |
412 | buffer->bin_buffer, | |
413 | buffer->bin_buffer_size); | |
414 | } | |
415 | up_read(&frag->frag_sem); | |
03607ace PA |
416 | } |
417 | ||
3c252b08 | 418 | vfree(buffer->bin_buffer); |
3c252b08 | 419 | |
ff4dd081 AV |
420 | configfs_release(inode, file); |
421 | return 0; | |
03607ace PA |
422 | } |
423 | ||
424 | ||
4b6f5d20 | 425 | const struct file_operations configfs_file_operations = { |
7fe1e79b BVA |
426 | .read_iter = configfs_read_iter, |
427 | .write_iter = configfs_write_iter, | |
7063fbf2 JB |
428 | .llseek = generic_file_llseek, |
429 | .open = configfs_open_file, | |
430 | .release = configfs_release, | |
431 | }; | |
432 | ||
03607ace | 433 | const struct file_operations configfs_bin_file_operations = { |
7fe1e79b BVA |
434 | .read_iter = configfs_bin_read_iter, |
435 | .write_iter = configfs_bin_write_iter, | |
03607ace PA |
436 | .llseek = NULL, /* bin file is not seekable */ |
437 | .open = configfs_open_bin_file, | |
438 | .release = configfs_release_bin_file, | |
439 | }; | |
440 | ||
7063fbf2 JB |
441 | /** |
442 | * configfs_create_file - create an attribute file for an item. | |
443 | * @item: item we're creating for. | |
444 | * @attr: atrribute descriptor. | |
445 | */ | |
446 | ||
447 | int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr) | |
448 | { | |
28444a2b AV |
449 | struct dentry *dir = item->ci_dentry; |
450 | struct configfs_dirent *parent_sd = dir->d_fsdata; | |
451 | umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG; | |
452 | int error = 0; | |
7063fbf2 | 453 | |
5955102c | 454 | inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL); |
28444a2b | 455 | error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, |
47320fbe | 456 | CONFIGFS_ITEM_ATTR, parent_sd->s_frag); |
5955102c | 457 | inode_unlock(d_inode(dir)); |
28444a2b AV |
458 | |
459 | return error; | |
7063fbf2 JB |
460 | } |
461 | ||
03607ace PA |
462 | /** |
463 | * configfs_create_bin_file - create a binary attribute file for an item. | |
464 | * @item: item we're creating for. | |
dd33f1f7 | 465 | * @bin_attr: atrribute descriptor. |
03607ace PA |
466 | */ |
467 | ||
468 | int configfs_create_bin_file(struct config_item *item, | |
469 | const struct configfs_bin_attribute *bin_attr) | |
470 | { | |
471 | struct dentry *dir = item->ci_dentry; | |
472 | struct configfs_dirent *parent_sd = dir->d_fsdata; | |
473 | umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG; | |
474 | int error = 0; | |
475 | ||
5955102c | 476 | inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL); |
03607ace | 477 | error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode, |
47320fbe | 478 | CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag); |
5955102c | 479 | inode_unlock(dir->d_inode); |
03607ace PA |
480 | |
481 | return error; | |
482 | } |