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1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * file.c - operations for regular (text) files.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
20 *
21 * Based on sysfs:
22 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
23 *
24 * configfs Copyright (C) 2005 Oracle. All rights reserved.
25 */
26
27#include <linux/fs.h>
28#include <linux/module.h>
29#include <linux/slab.h>
30#include <linux/mutex.h>
31#include <linux/vmalloc.h>
32#include <asm/uaccess.h>
33
34#include <linux/configfs.h>
35#include "configfs_internal.h"
36
37/*
38 * A simple attribute can only be 4096 characters. Why 4k? Because the
39 * original code limited it to PAGE_SIZE. That's a bad idea, though,
40 * because an attribute of 16k on ia64 won't work on x86. So we limit to
41 * 4k, our minimum common page size.
42 */
43#define SIMPLE_ATTR_SIZE 4096
44
45struct configfs_buffer {
46 size_t count;
47 loff_t pos;
48 char * page;
49 struct configfs_item_operations * ops;
50 struct mutex mutex;
51 int needs_read_fill;
52 bool read_in_progress;
53 bool write_in_progress;
54 char *bin_buffer;
55 int bin_buffer_size;
56};
57
58
59/**
60 * fill_read_buffer - allocate and fill buffer from item.
61 * @dentry: dentry pointer.
62 * @buffer: data buffer for file.
63 *
64 * Allocate @buffer->page, if it hasn't been already, then call the
65 * config_item's show() method to fill the buffer with this attribute's
66 * data.
67 * This is called only once, on the file's first read.
68 */
69static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
70{
71 struct configfs_attribute * attr = to_attr(dentry);
72 struct config_item * item = to_item(dentry->d_parent);
73 int ret = 0;
74 ssize_t count;
75
76 if (!buffer->page)
77 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
78 if (!buffer->page)
79 return -ENOMEM;
80
81 count = attr->show(item, buffer->page);
82
83 buffer->needs_read_fill = 0;
84 BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
85 if (count >= 0)
86 buffer->count = count;
87 else
88 ret = count;
89 return ret;
90}
91
92/**
93 * configfs_read_file - read an attribute.
94 * @file: file pointer.
95 * @buf: buffer to fill.
96 * @count: number of bytes to read.
97 * @ppos: starting offset in file.
98 *
99 * Userspace wants to read an attribute file. The attribute descriptor
100 * is in the file's ->d_fsdata. The target item is in the directory's
101 * ->d_fsdata.
102 *
103 * We call fill_read_buffer() to allocate and fill the buffer from the
104 * item's show() method exactly once (if the read is happening from
105 * the beginning of the file). That should fill the entire buffer with
106 * all the data the item has to offer for that attribute.
107 * We then call flush_read_buffer() to copy the buffer to userspace
108 * in the increments specified.
109 */
110
111static ssize_t
112configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
113{
114 struct configfs_buffer * buffer = file->private_data;
115 ssize_t retval = 0;
116
117 mutex_lock(&buffer->mutex);
118 if (buffer->needs_read_fill) {
119 if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
120 goto out;
121 }
122 pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
123 __func__, count, *ppos, buffer->page);
124 retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
125 buffer->count);
126out:
127 mutex_unlock(&buffer->mutex);
128 return retval;
129}
130
131/**
132 * configfs_read_bin_file - read a binary attribute.
133 * @file: file pointer.
134 * @buf: buffer to fill.
135 * @count: number of bytes to read.
136 * @ppos: starting offset in file.
137 *
138 * Userspace wants to read a binary attribute file. The attribute
139 * descriptor is in the file's ->d_fsdata. The target item is in the
140 * directory's ->d_fsdata.
141 *
142 * We check whether we need to refill the buffer. If so we will
143 * call the attributes' attr->read() twice. The first time we
144 * will pass a NULL as a buffer pointer, which the attributes' method
145 * will use to return the size of the buffer required. If no error
146 * occurs we will allocate the buffer using vmalloc and call
147 * attr->read() again passing that buffer as an argument.
148 * Then we just copy to user-space using simple_read_from_buffer.
149 */
150
151static ssize_t
152configfs_read_bin_file(struct file *file, char __user *buf,
153 size_t count, loff_t *ppos)
154{
155 struct configfs_buffer *buffer = file->private_data;
156 struct dentry *dentry = file->f_path.dentry;
157 struct config_item *item = to_item(dentry->d_parent);
158 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
159 ssize_t retval = 0;
160 ssize_t len = min_t(size_t, count, PAGE_SIZE);
161
162 mutex_lock(&buffer->mutex);
163
164 /* we don't support switching read/write modes */
165 if (buffer->write_in_progress) {
166 retval = -ETXTBSY;
167 goto out;
168 }
169 buffer->read_in_progress = 1;
170
171 if (buffer->needs_read_fill) {
172 /* perform first read with buf == NULL to get extent */
173 len = bin_attr->read(item, NULL, 0);
174 if (len <= 0) {
175 retval = len;
176 goto out;
177 }
178
179 /* do not exceed the maximum value */
180 if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
181 retval = -EFBIG;
182 goto out;
183 }
184
185 buffer->bin_buffer = vmalloc(len);
186 if (buffer->bin_buffer == NULL) {
187 retval = -ENOMEM;
188 goto out;
189 }
190 buffer->bin_buffer_size = len;
191
192 /* perform second read to fill buffer */
193 len = bin_attr->read(item, buffer->bin_buffer, len);
194 if (len < 0) {
195 retval = len;
196 vfree(buffer->bin_buffer);
197 buffer->bin_buffer_size = 0;
198 buffer->bin_buffer = NULL;
199 goto out;
200 }
201
202 buffer->needs_read_fill = 0;
203 }
204
205 retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
206 buffer->bin_buffer_size);
207out:
208 mutex_unlock(&buffer->mutex);
209 return retval;
210}
211
212
213/**
214 * fill_write_buffer - copy buffer from userspace.
215 * @buffer: data buffer for file.
216 * @buf: data from user.
217 * @count: number of bytes in @userbuf.
218 *
219 * Allocate @buffer->page if it hasn't been already, then
220 * copy the user-supplied buffer into it.
221 */
222
223static int
224fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
225{
226 int error;
227
228 if (!buffer->page)
229 buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
230 if (!buffer->page)
231 return -ENOMEM;
232
233 if (count >= SIMPLE_ATTR_SIZE)
234 count = SIMPLE_ATTR_SIZE - 1;
235 error = copy_from_user(buffer->page,buf,count);
236 buffer->needs_read_fill = 1;
237 /* if buf is assumed to contain a string, terminate it by \0,
238 * so e.g. sscanf() can scan the string easily */
239 buffer->page[count] = 0;
240 return error ? -EFAULT : count;
241}
242
243
244/**
245 * flush_write_buffer - push buffer to config_item.
246 * @dentry: dentry to the attribute
247 * @buffer: data buffer for file.
248 * @count: number of bytes
249 *
250 * Get the correct pointers for the config_item and the attribute we're
251 * dealing with, then call the store() method for the attribute,
252 * passing the buffer that we acquired in fill_write_buffer().
253 */
254
255static int
256flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
257{
258 struct configfs_attribute * attr = to_attr(dentry);
259 struct config_item * item = to_item(dentry->d_parent);
260
261 return attr->store(item, buffer->page, count);
262}
263
264
265/**
266 * configfs_write_file - write an attribute.
267 * @file: file pointer
268 * @buf: data to write
269 * @count: number of bytes
270 * @ppos: starting offset
271 *
272 * Similar to configfs_read_file(), though working in the opposite direction.
273 * We allocate and fill the data from the user in fill_write_buffer(),
274 * then push it to the config_item in flush_write_buffer().
275 * There is no easy way for us to know if userspace is only doing a partial
276 * write, so we don't support them. We expect the entire buffer to come
277 * on the first write.
278 * Hint: if you're writing a value, first read the file, modify only the
279 * the value you're changing, then write entire buffer back.
280 */
281
282static ssize_t
283configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
284{
285 struct configfs_buffer * buffer = file->private_data;
286 ssize_t len;
287
288 mutex_lock(&buffer->mutex);
289 len = fill_write_buffer(buffer, buf, count);
290 if (len > 0)
291 len = flush_write_buffer(file->f_path.dentry, buffer, len);
292 if (len > 0)
293 *ppos += len;
294 mutex_unlock(&buffer->mutex);
295 return len;
296}
297
298/**
299 * configfs_write_bin_file - write a binary attribute.
300 * @file: file pointer
301 * @buf: data to write
302 * @count: number of bytes
303 * @ppos: starting offset
304 *
305 * Writing to a binary attribute file is similar to a normal read.
306 * We buffer the consecutive writes (binary attribute files do not
307 * support lseek) in a continuously growing buffer, but we don't
308 * commit until the close of the file.
309 */
310
311static ssize_t
312configfs_write_bin_file(struct file *file, const char __user *buf,
313 size_t count, loff_t *ppos)
314{
315 struct configfs_buffer *buffer = file->private_data;
316 struct dentry *dentry = file->f_path.dentry;
317 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
318 void *tbuf = NULL;
319 ssize_t len;
320
321 mutex_lock(&buffer->mutex);
322
323 /* we don't support switching read/write modes */
324 if (buffer->read_in_progress) {
325 len = -ETXTBSY;
326 goto out;
327 }
328 buffer->write_in_progress = 1;
329
330 /* buffer grows? */
331 if (*ppos + count > buffer->bin_buffer_size) {
332
333 if (bin_attr->cb_max_size &&
334 *ppos + count > bin_attr->cb_max_size) {
335 len = -EFBIG;
336 }
337
338 tbuf = vmalloc(*ppos + count);
339 if (tbuf == NULL) {
340 len = -ENOMEM;
341 goto out;
342 }
343
344 /* copy old contents */
345 if (buffer->bin_buffer) {
346 memcpy(tbuf, buffer->bin_buffer,
347 buffer->bin_buffer_size);
348 vfree(buffer->bin_buffer);
349 }
350
351 /* clear the new area */
352 memset(tbuf + buffer->bin_buffer_size, 0,
353 *ppos + count - buffer->bin_buffer_size);
354 buffer->bin_buffer = tbuf;
355 buffer->bin_buffer_size = *ppos + count;
356 }
357
358 len = simple_write_to_buffer(buffer->bin_buffer,
359 buffer->bin_buffer_size, ppos, buf, count);
360 if (len > 0)
361 *ppos += len;
362out:
363 mutex_unlock(&buffer->mutex);
364 return len;
365}
366
367static int check_perm(struct inode * inode, struct file * file, int type)
368{
369 struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
370 struct configfs_attribute * attr = to_attr(file->f_path.dentry);
371 struct configfs_bin_attribute *bin_attr = NULL;
372 struct configfs_buffer * buffer;
373 struct configfs_item_operations * ops = NULL;
374 int error = 0;
375
376 if (!item || !attr)
377 goto Einval;
378
379 if (type & CONFIGFS_ITEM_BIN_ATTR)
380 bin_attr = to_bin_attr(file->f_path.dentry);
381
382 /* Grab the module reference for this attribute if we have one */
383 if (!try_module_get(attr->ca_owner)) {
384 error = -ENODEV;
385 goto Done;
386 }
387
388 if (item->ci_type)
389 ops = item->ci_type->ct_item_ops;
390 else
391 goto Eaccess;
392
393 /* File needs write support.
394 * The inode's perms must say it's ok,
395 * and we must have a store method.
396 */
397 if (file->f_mode & FMODE_WRITE) {
398 if (!(inode->i_mode & S_IWUGO))
399 goto Eaccess;
400
401 if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
402 goto Eaccess;
403
404 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
405 goto Eaccess;
406 }
407
408 /* File needs read support.
409 * The inode's perms must say it's ok, and we there
410 * must be a show method for it.
411 */
412 if (file->f_mode & FMODE_READ) {
413 if (!(inode->i_mode & S_IRUGO))
414 goto Eaccess;
415
416 if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
417 goto Eaccess;
418
419 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
420 goto Eaccess;
421 }
422
423 /* No error? Great, allocate a buffer for the file, and store it
424 * it in file->private_data for easy access.
425 */
426 buffer = kzalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
427 if (!buffer) {
428 error = -ENOMEM;
429 goto Enomem;
430 }
431 mutex_init(&buffer->mutex);
432 buffer->needs_read_fill = 1;
433 buffer->read_in_progress = 0;
434 buffer->write_in_progress = 0;
435 buffer->ops = ops;
436 file->private_data = buffer;
437 goto Done;
438
439 Einval:
440 error = -EINVAL;
441 goto Done;
442 Eaccess:
443 error = -EACCES;
444 Enomem:
445 module_put(attr->ca_owner);
446 Done:
447 if (error && item)
448 config_item_put(item);
449 return error;
450}
451
452static int configfs_release(struct inode *inode, struct file *filp)
453{
454 struct config_item * item = to_item(filp->f_path.dentry->d_parent);
455 struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
456 struct module * owner = attr->ca_owner;
457 struct configfs_buffer * buffer = filp->private_data;
458
459 if (item)
460 config_item_put(item);
461 /* After this point, attr should not be accessed. */
462 module_put(owner);
463
464 if (buffer) {
465 if (buffer->page)
466 free_page((unsigned long)buffer->page);
467 mutex_destroy(&buffer->mutex);
468 kfree(buffer);
469 }
470 return 0;
471}
472
473static int configfs_open_file(struct inode *inode, struct file *filp)
474{
475 return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
476}
477
478static int configfs_open_bin_file(struct inode *inode, struct file *filp)
479{
480 return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
481}
482
483static int configfs_release_bin_file(struct inode *inode, struct file *filp)
484{
485 struct configfs_buffer *buffer = filp->private_data;
486 struct dentry *dentry = filp->f_path.dentry;
487 struct config_item *item = to_item(dentry->d_parent);
488 struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
489 ssize_t len = 0;
490 int ret;
491
492 buffer->read_in_progress = 0;
493
494 if (buffer->write_in_progress) {
495 buffer->write_in_progress = 0;
496
497 len = bin_attr->write(item, buffer->bin_buffer,
498 buffer->bin_buffer_size);
499
500 /* vfree on NULL is safe */
501 vfree(buffer->bin_buffer);
502 buffer->bin_buffer = NULL;
503 buffer->bin_buffer_size = 0;
504 buffer->needs_read_fill = 1;
505 }
506
507 ret = configfs_release(inode, filp);
508 if (len < 0)
509 return len;
510 return ret;
511}
512
513
514const struct file_operations configfs_file_operations = {
515 .read = configfs_read_file,
516 .write = configfs_write_file,
517 .llseek = generic_file_llseek,
518 .open = configfs_open_file,
519 .release = configfs_release,
520};
521
522const struct file_operations configfs_bin_file_operations = {
523 .read = configfs_read_bin_file,
524 .write = configfs_write_bin_file,
525 .llseek = NULL, /* bin file is not seekable */
526 .open = configfs_open_bin_file,
527 .release = configfs_release_bin_file,
528};
529
530/**
531 * configfs_create_file - create an attribute file for an item.
532 * @item: item we're creating for.
533 * @attr: atrribute descriptor.
534 */
535
536int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
537{
538 struct dentry *dir = item->ci_dentry;
539 struct configfs_dirent *parent_sd = dir->d_fsdata;
540 umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
541 int error = 0;
542
543 inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
544 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
545 CONFIGFS_ITEM_ATTR);
546 inode_unlock(d_inode(dir));
547
548 return error;
549}
550
551/**
552 * configfs_create_bin_file - create a binary attribute file for an item.
553 * @item: item we're creating for.
554 * @attr: atrribute descriptor.
555 */
556
557int configfs_create_bin_file(struct config_item *item,
558 const struct configfs_bin_attribute *bin_attr)
559{
560 struct dentry *dir = item->ci_dentry;
561 struct configfs_dirent *parent_sd = dir->d_fsdata;
562 umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
563 int error = 0;
564
565 inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
566 error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
567 CONFIGFS_ITEM_BIN_ATTR);
568 inode_unlock(dir->d_inode);
569
570 return error;
571}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * file.c - operations for regular (text) files.
4 *
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>
13#include <linux/slab.h>
14#include <linux/mutex.h>
15#include <linux/vmalloc.h>
16#include <linux/uaccess.h>
17#include <linux/uio.h>
18#include <linux/configfs.h>
19#include "configfs_internal.h"
20
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
28
29struct configfs_buffer {
30 size_t count;
31 loff_t pos;
32 char * page;
33 struct configfs_item_operations * ops;
34 struct mutex mutex;
35 int needs_read_fill;
36 bool read_in_progress;
37 bool write_in_progress;
38 char *bin_buffer;
39 int bin_buffer_size;
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 };
47};
48
49static 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}
55
56static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
57{
58 struct configfs_fragment *frag = to_frag(file);
59 ssize_t count = -ENOENT;
60
61 if (!buffer->page)
62 buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
63 if (!buffer->page)
64 return -ENOMEM;
65
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
71 if (count < 0)
72 return count;
73 if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
74 return -EIO;
75 buffer->needs_read_fill = 0;
76 buffer->count = count;
77 return 0;
78}
79
80static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
81{
82 struct file *file = iocb->ki_filp;
83 struct configfs_buffer *buffer = file->private_data;
84 ssize_t retval = 0;
85
86 mutex_lock(&buffer->mutex);
87 if (buffer->needs_read_fill) {
88 retval = fill_read_buffer(file, buffer);
89 if (retval)
90 goto out;
91 }
92 pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
93 __func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
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);
98 iocb->ki_pos += retval;
99 if (retval == 0)
100 retval = -EFAULT;
101out:
102 mutex_unlock(&buffer->mutex);
103 return retval;
104}
105
106static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
107{
108 struct file *file = iocb->ki_filp;
109 struct configfs_fragment *frag = to_frag(file);
110 struct configfs_buffer *buffer = file->private_data;
111 ssize_t retval = 0;
112 ssize_t len;
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 }
121 buffer->read_in_progress = true;
122
123 if (buffer->needs_read_fill) {
124 /* perform first read with buf == NULL to get extent */
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);
131 if (len <= 0) {
132 retval = len;
133 goto out;
134 }
135
136 /* do not exceed the maximum value */
137 if (buffer->cb_max_size && len > buffer->cb_max_size) {
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 */
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);
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
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);
172 iocb->ki_pos += retval;
173 if (retval == 0)
174 retval = -EFAULT;
175out:
176 mutex_unlock(&buffer->mutex);
177 return retval;
178}
179
180/* Fill @buffer with data coming from @from. */
181static int fill_write_buffer(struct configfs_buffer *buffer,
182 struct iov_iter *from)
183{
184 int copied;
185
186 if (!buffer->page)
187 buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
188 if (!buffer->page)
189 return -ENOMEM;
190
191 copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
192 buffer->needs_read_fill = 1;
193 /* if buf is assumed to contain a string, terminate it by \0,
194 * so e.g. sscanf() can scan the string easily */
195 buffer->page[copied] = 0;
196 return copied ? : -EFAULT;
197}
198
199static int
200flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t count)
201{
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;
210}
211
212
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.
219 */
220static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
221{
222 struct file *file = iocb->ki_filp;
223 struct configfs_buffer *buffer = file->private_data;
224 int len;
225
226 mutex_lock(&buffer->mutex);
227 len = fill_write_buffer(buffer, from);
228 if (len > 0)
229 len = flush_write_buffer(file, buffer, len);
230 if (len > 0)
231 iocb->ki_pos += len;
232 mutex_unlock(&buffer->mutex);
233 return len;
234}
235
236static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
237 struct iov_iter *from)
238{
239 struct file *file = iocb->ki_filp;
240 struct configfs_buffer *buffer = file->private_data;
241 void *tbuf = NULL;
242 size_t end_offset;
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 }
252 buffer->write_in_progress = true;
253
254 /* buffer grows? */
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) {
258 len = -EFBIG;
259 goto out;
260 }
261
262 tbuf = vmalloc(end_offset);
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,
277 end_offset - buffer->bin_buffer_size);
278 buffer->bin_buffer = tbuf;
279 buffer->bin_buffer_size = end_offset;
280 }
281
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;
285out:
286 mutex_unlock(&buffer->mutex);
287 return len ? : -EFAULT;
288}
289
290static int __configfs_open_file(struct inode *inode, struct file *file, int type)
291{
292 struct dentry *dentry = file->f_path.dentry;
293 struct configfs_fragment *frag = to_frag(file);
294 struct configfs_attribute *attr;
295 struct configfs_buffer *buffer;
296 int error;
297
298 error = -ENOMEM;
299 buffer = kzalloc(sizeof(struct configfs_buffer), GFP_KERNEL);
300 if (!buffer)
301 goto out;
302
303 error = -ENOENT;
304 down_read(&frag->frag_sem);
305 if (unlikely(frag->frag_dead))
306 goto out_free_buffer;
307
308 error = -EINVAL;
309 buffer->item = to_item(dentry->d_parent);
310 if (!buffer->item)
311 goto out_free_buffer;
312
313 attr = to_attr(dentry);
314 if (!attr)
315 goto out_free_buffer;
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 }
323
324 buffer->owner = attr->ca_owner;
325 /* Grab the module reference for this attribute if we have one */
326 error = -ENODEV;
327 if (!try_module_get(buffer->owner))
328 goto out_free_buffer;
329
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;
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) {
341 if (!(inode->i_mode & S_IWUGO))
342 goto out_put_module;
343 if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
344 goto out_put_module;
345 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->write)
346 goto out_put_module;
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) {
354 if (!(inode->i_mode & S_IRUGO))
355 goto out_put_module;
356 if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
357 goto out_put_module;
358 if ((type & CONFIGFS_ITEM_BIN_ATTR) && !buffer->bin_attr->read)
359 goto out_put_module;
360 }
361
362 mutex_init(&buffer->mutex);
363 buffer->needs_read_fill = 1;
364 buffer->read_in_progress = false;
365 buffer->write_in_progress = false;
366 file->private_data = buffer;
367 up_read(&frag->frag_sem);
368 return 0;
369
370out_put_module:
371 module_put(buffer->owner);
372out_free_buffer:
373 up_read(&frag->frag_sem);
374 kfree(buffer);
375out:
376 return error;
377}
378
379static int configfs_release(struct inode *inode, struct file *filp)
380{
381 struct configfs_buffer *buffer = filp->private_data;
382
383 module_put(buffer->owner);
384 if (buffer->page)
385 free_page((unsigned long)buffer->page);
386 mutex_destroy(&buffer->mutex);
387 kfree(buffer);
388 return 0;
389}
390
391static int configfs_open_file(struct inode *inode, struct file *filp)
392{
393 return __configfs_open_file(inode, filp, CONFIGFS_ITEM_ATTR);
394}
395
396static int configfs_open_bin_file(struct inode *inode, struct file *filp)
397{
398 return __configfs_open_file(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
399}
400
401static int configfs_release_bin_file(struct inode *inode, struct file *file)
402{
403 struct configfs_buffer *buffer = file->private_data;
404
405 if (buffer->write_in_progress) {
406 struct configfs_fragment *frag = to_frag(file);
407
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);
416 }
417
418 vfree(buffer->bin_buffer);
419
420 configfs_release(inode, file);
421 return 0;
422}
423
424
425const struct file_operations configfs_file_operations = {
426 .read_iter = configfs_read_iter,
427 .write_iter = configfs_write_iter,
428 .llseek = generic_file_llseek,
429 .open = configfs_open_file,
430 .release = configfs_release,
431};
432
433const struct file_operations configfs_bin_file_operations = {
434 .read_iter = configfs_bin_read_iter,
435 .write_iter = configfs_bin_write_iter,
436 .llseek = NULL, /* bin file is not seekable */
437 .open = configfs_open_bin_file,
438 .release = configfs_release_bin_file,
439};
440
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
447int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
448{
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;
453
454 inode_lock_nested(d_inode(dir), I_MUTEX_NORMAL);
455 error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode,
456 CONFIGFS_ITEM_ATTR, parent_sd->s_frag);
457 inode_unlock(d_inode(dir));
458
459 return error;
460}
461
462/**
463 * configfs_create_bin_file - create a binary attribute file for an item.
464 * @item: item we're creating for.
465 * @bin_attr: atrribute descriptor.
466 */
467
468int 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
476 inode_lock_nested(dir->d_inode, I_MUTEX_NORMAL);
477 error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
478 CONFIGFS_ITEM_BIN_ATTR, parent_sd->s_frag);
479 inode_unlock(dir->d_inode);
480
481 return error;
482}