~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/ecryptfs/read_write.c

Version: ~ [ linux-5.16-rc3 ] ~ [ linux-5.15.5 ] ~ [ linux-5.14.21 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.82 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.162 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.218 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.256 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.291 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.293 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /**
  2  * eCryptfs: Linux filesystem encryption layer
  3  *
  4  * Copyright (C) 2007 International Business Machines Corp.
  5  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  6  *
  7  * This program is free software; you can redistribute it and/or
  8  * modify it under the terms of the GNU General Public License as
  9  * published by the Free Software Foundation; either version 2 of the
 10  * License, or (at your option) any later version.
 11  *
 12  * This program is distributed in the hope that it will be useful, but
 13  * WITHOUT ANY WARRANTY; without even the implied warranty of
 14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 15  * General Public License for more details.
 16  *
 17  * You should have received a copy of the GNU General Public License
 18  * along with this program; if not, write to the Free Software
 19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 20  * 02111-1307, USA.
 21  */
 22 
 23 #include <linux/fs.h>
 24 #include <linux/pagemap.h>
 25 #include "ecryptfs_kernel.h"
 26 
 27 /**
 28  * ecryptfs_write_lower
 29  * @ecryptfs_inode: The eCryptfs inode
 30  * @data: Data to write
 31  * @offset: Byte offset in the lower file to which to write the data
 32  * @size: Number of bytes from @data to write at @offset in the lower
 33  *        file
 34  *
 35  * Write data to the lower file.
 36  *
 37  * Returns bytes written on success; less than zero on error
 38  */
 39 int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
 40                          loff_t offset, size_t size)
 41 {
 42         struct file *lower_file;
 43         ssize_t rc;
 44 
 45         lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
 46         if (!lower_file)
 47                 return -EIO;
 48         rc = kernel_write(lower_file, data, size, offset);
 49         mark_inode_dirty_sync(ecryptfs_inode);
 50         return rc;
 51 }
 52 
 53 /**
 54  * ecryptfs_write_lower_page_segment
 55  * @ecryptfs_inode: The eCryptfs inode
 56  * @page_for_lower: The page containing the data to be written to the
 57  *                  lower file
 58  * @offset_in_page: The offset in the @page_for_lower from which to
 59  *                  start writing the data
 60  * @size: The amount of data from @page_for_lower to write to the
 61  *        lower file
 62  *
 63  * Determines the byte offset in the file for the given page and
 64  * offset within the page, maps the page, and makes the call to write
 65  * the contents of @page_for_lower to the lower inode.
 66  *
 67  * Returns zero on success; non-zero otherwise
 68  */
 69 int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
 70                                       struct page *page_for_lower,
 71                                       size_t offset_in_page, size_t size)
 72 {
 73         char *virt;
 74         loff_t offset;
 75         int rc;
 76 
 77         offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
 78                   + offset_in_page);
 79         virt = kmap(page_for_lower);
 80         rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
 81         if (rc > 0)
 82                 rc = 0;
 83         kunmap(page_for_lower);
 84         return rc;
 85 }
 86 
 87 /**
 88  * ecryptfs_write
 89  * @ecryptfs_inode: The eCryptfs file into which to write
 90  * @data: Virtual address where data to write is located
 91  * @offset: Offset in the eCryptfs file at which to begin writing the
 92  *          data from @data
 93  * @size: The number of bytes to write from @data
 94  *
 95  * Write an arbitrary amount of data to an arbitrary location in the
 96  * eCryptfs inode page cache. This is done on a page-by-page, and then
 97  * by an extent-by-extent, basis; individual extents are encrypted and
 98  * written to the lower page cache (via VFS writes). This function
 99  * takes care of all the address translation to locations in the lower
100  * filesystem; it also handles truncate events, writing out zeros
101  * where necessary.
102  *
103  * Returns zero on success; non-zero otherwise
104  */
105 int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
106                    size_t size)
107 {
108         struct page *ecryptfs_page;
109         struct ecryptfs_crypt_stat *crypt_stat;
110         char *ecryptfs_page_virt;
111         loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
112         loff_t data_offset = 0;
113         loff_t pos;
114         int rc = 0;
115 
116         crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
117         /*
118          * if we are writing beyond current size, then start pos
119          * at the current size - we'll fill in zeros from there.
120          */
121         if (offset > ecryptfs_file_size)
122                 pos = ecryptfs_file_size;
123         else
124                 pos = offset;
125         while (pos < (offset + size)) {
126                 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
127                 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
128                 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
129                 loff_t total_remaining_bytes = ((offset + size) - pos);
130 
131                 if (fatal_signal_pending(current)) {
132                         rc = -EINTR;
133                         break;
134                 }
135 
136                 if (num_bytes > total_remaining_bytes)
137                         num_bytes = total_remaining_bytes;
138                 if (pos < offset) {
139                         /* remaining zeros to write, up to destination offset */
140                         loff_t total_remaining_zeros = (offset - pos);
141 
142                         if (num_bytes > total_remaining_zeros)
143                                 num_bytes = total_remaining_zeros;
144                 }
145                 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode,
146                                                          ecryptfs_page_idx);
147                 if (IS_ERR(ecryptfs_page)) {
148                         rc = PTR_ERR(ecryptfs_page);
149                         printk(KERN_ERR "%s: Error getting page at "
150                                "index [%ld] from eCryptfs inode "
151                                "mapping; rc = [%d]\n", __func__,
152                                ecryptfs_page_idx, rc);
153                         goto out;
154                 }
155                 ecryptfs_page_virt = kmap_atomic(ecryptfs_page);
156 
157                 /*
158                  * pos: where we're now writing, offset: where the request was
159                  * If current pos is before request, we are filling zeros
160                  * If we are at or beyond request, we are writing the *data*
161                  * If we're in a fresh page beyond eof, zero it in either case
162                  */
163                 if (pos < offset || !start_offset_in_page) {
164                         /* We are extending past the previous end of the file.
165                          * Fill in zero values to the end of the page */
166                         memset(((char *)ecryptfs_page_virt
167                                 + start_offset_in_page), 0,
168                                 PAGE_CACHE_SIZE - start_offset_in_page);
169                 }
170 
171                 /* pos >= offset, we are now writing the data request */
172                 if (pos >= offset) {
173                         memcpy(((char *)ecryptfs_page_virt
174                                 + start_offset_in_page),
175                                (data + data_offset), num_bytes);
176                         data_offset += num_bytes;
177                 }
178                 kunmap_atomic(ecryptfs_page_virt);
179                 flush_dcache_page(ecryptfs_page);
180                 SetPageUptodate(ecryptfs_page);
181                 unlock_page(ecryptfs_page);
182                 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
183                         rc = ecryptfs_encrypt_page(ecryptfs_page);
184                 else
185                         rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
186                                                 ecryptfs_page,
187                                                 start_offset_in_page,
188                                                 data_offset);
189                 page_cache_release(ecryptfs_page);
190                 if (rc) {
191                         printk(KERN_ERR "%s: Error encrypting "
192                                "page; rc = [%d]\n", __func__, rc);
193                         goto out;
194                 }
195                 pos += num_bytes;
196         }
197         if (pos > ecryptfs_file_size) {
198                 i_size_write(ecryptfs_inode, pos);
199                 if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) {
200                         int rc2;
201 
202                         rc2 = ecryptfs_write_inode_size_to_metadata(
203                                                                 ecryptfs_inode);
204                         if (rc2) {
205                                 printk(KERN_ERR "Problem with "
206                                        "ecryptfs_write_inode_size_to_metadata; "
207                                        "rc = [%d]\n", rc2);
208                                 if (!rc)
209                                         rc = rc2;
210                                 goto out;
211                         }
212                 }
213         }
214 out:
215         return rc;
216 }
217 
218 /**
219  * ecryptfs_read_lower
220  * @data: The read data is stored here by this function
221  * @offset: Byte offset in the lower file from which to read the data
222  * @size: Number of bytes to read from @offset of the lower file and
223  *        store into @data
224  * @ecryptfs_inode: The eCryptfs inode
225  *
226  * Read @size bytes of data at byte offset @offset from the lower
227  * inode into memory location @data.
228  *
229  * Returns bytes read on success; 0 on EOF; less than zero on error
230  */
231 int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
232                         struct inode *ecryptfs_inode)
233 {
234         struct file *lower_file;
235         lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file;
236         if (!lower_file)
237                 return -EIO;
238         return kernel_read(lower_file, offset, data, size);
239 }
240 
241 /**
242  * ecryptfs_read_lower_page_segment
243  * @page_for_ecryptfs: The page into which data for eCryptfs will be
244  *                     written
245  * @offset_in_page: Offset in @page_for_ecryptfs from which to start
246  *                  writing
247  * @size: The number of bytes to write into @page_for_ecryptfs
248  * @ecryptfs_inode: The eCryptfs inode
249  *
250  * Determines the byte offset in the file for the given page and
251  * offset within the page, maps the page, and makes the call to read
252  * the contents of @page_for_ecryptfs from the lower inode.
253  *
254  * Returns zero on success; non-zero otherwise
255  */
256 int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
257                                      pgoff_t page_index,
258                                      size_t offset_in_page, size_t size,
259                                      struct inode *ecryptfs_inode)
260 {
261         char *virt;
262         loff_t offset;
263         int rc;
264 
265         offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
266         virt = kmap(page_for_ecryptfs);
267         rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
268         if (rc > 0)
269                 rc = 0;
270         kunmap(page_for_ecryptfs);
271         flush_dcache_page(page_for_ecryptfs);
272         return rc;
273 }
274 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp