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1a59d1b8 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
09d02efa | 2 | /* |
da0102a1 MH |
3 | * eCryptfs: Linux filesystem encryption layer |
4 | * | |
5 | * Copyright (C) 2007 International Business Machines Corp. | |
6 | * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> | |
da0102a1 MH |
7 | */ |
8 | ||
9 | #include <linux/fs.h> | |
10 | #include <linux/pagemap.h> | |
174cd4b1 IM |
11 | #include <linux/sched/signal.h> |
12 | ||
da0102a1 MH |
13 | #include "ecryptfs_kernel.h" |
14 | ||
15 | /** | |
16 | * ecryptfs_write_lower | |
17 | * @ecryptfs_inode: The eCryptfs inode | |
18 | * @data: Data to write | |
19 | * @offset: Byte offset in the lower file to which to write the data | |
20 | * @size: Number of bytes from @data to write at @offset in the lower | |
21 | * file | |
22 | * | |
23 | * Write data to the lower file. | |
24 | * | |
96a7b9c2 | 25 | * Returns bytes written on success; less than zero on error |
da0102a1 MH |
26 | */ |
27 | int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, | |
28 | loff_t offset, size_t size) | |
29 | { | |
f61500e0 | 30 | struct file *lower_file; |
96a7b9c2 | 31 | ssize_t rc; |
da0102a1 | 32 | |
f61500e0 TH |
33 | lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; |
34 | if (!lower_file) | |
35 | return -EIO; | |
e13ec939 | 36 | rc = kernel_write(lower_file, data, size, &offset); |
da0102a1 MH |
37 | mark_inode_dirty_sync(ecryptfs_inode); |
38 | return rc; | |
39 | } | |
40 | ||
41 | /** | |
42 | * ecryptfs_write_lower_page_segment | |
43 | * @ecryptfs_inode: The eCryptfs inode | |
44 | * @page_for_lower: The page containing the data to be written to the | |
45 | * lower file | |
46 | * @offset_in_page: The offset in the @page_for_lower from which to | |
47 | * start writing the data | |
48 | * @size: The amount of data from @page_for_lower to write to the | |
49 | * lower file | |
50 | * | |
51 | * Determines the byte offset in the file for the given page and | |
52 | * offset within the page, maps the page, and makes the call to write | |
53 | * the contents of @page_for_lower to the lower inode. | |
54 | * | |
55 | * Returns zero on success; non-zero otherwise | |
56 | */ | |
57 | int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, | |
58 | struct page *page_for_lower, | |
59 | size_t offset_in_page, size_t size) | |
60 | { | |
61 | char *virt; | |
62 | loff_t offset; | |
63 | int rc; | |
64 | ||
09cbfeaf | 65 | offset = ((((loff_t)page_for_lower->index) << PAGE_SHIFT) |
d6a13c17 | 66 | + offset_in_page); |
da0102a1 MH |
67 | virt = kmap(page_for_lower); |
68 | rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); | |
96a7b9c2 TH |
69 | if (rc > 0) |
70 | rc = 0; | |
da0102a1 MH |
71 | kunmap(page_for_lower); |
72 | return rc; | |
73 | } | |
74 | ||
75 | /** | |
76 | * ecryptfs_write | |
48c1e44a | 77 | * @ecryptfs_inode: The eCryptfs file into which to write |
da0102a1 MH |
78 | * @data: Virtual address where data to write is located |
79 | * @offset: Offset in the eCryptfs file at which to begin writing the | |
80 | * data from @data | |
81 | * @size: The number of bytes to write from @data | |
82 | * | |
83 | * Write an arbitrary amount of data to an arbitrary location in the | |
84 | * eCryptfs inode page cache. This is done on a page-by-page, and then | |
85 | * by an extent-by-extent, basis; individual extents are encrypted and | |
86 | * written to the lower page cache (via VFS writes). This function | |
87 | * takes care of all the address translation to locations in the lower | |
88 | * filesystem; it also handles truncate events, writing out zeros | |
89 | * where necessary. | |
90 | * | |
91 | * Returns zero on success; non-zero otherwise | |
92 | */ | |
48c1e44a | 93 | int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, |
da0102a1 MH |
94 | size_t size) |
95 | { | |
96 | struct page *ecryptfs_page; | |
13a791b4 | 97 | struct ecryptfs_crypt_stat *crypt_stat; |
da0102a1 | 98 | char *ecryptfs_page_virt; |
13a791b4 | 99 | loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); |
da0102a1 MH |
100 | loff_t data_offset = 0; |
101 | loff_t pos; | |
102 | int rc = 0; | |
103 | ||
13a791b4 | 104 | crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; |
7a3f595c ES |
105 | /* |
106 | * if we are writing beyond current size, then start pos | |
107 | * at the current size - we'll fill in zeros from there. | |
108 | */ | |
da0102a1 MH |
109 | if (offset > ecryptfs_file_size) |
110 | pos = ecryptfs_file_size; | |
111 | else | |
112 | pos = offset; | |
113 | while (pos < (offset + size)) { | |
09cbfeaf KS |
114 | pgoff_t ecryptfs_page_idx = (pos >> PAGE_SHIFT); |
115 | size_t start_offset_in_page = (pos & ~PAGE_MASK); | |
116 | size_t num_bytes = (PAGE_SIZE - start_offset_in_page); | |
684a3ff7 | 117 | loff_t total_remaining_bytes = ((offset + size) - pos); |
da0102a1 | 118 | |
5e6f0d76 TH |
119 | if (fatal_signal_pending(current)) { |
120 | rc = -EINTR; | |
121 | break; | |
122 | } | |
123 | ||
da0102a1 MH |
124 | if (num_bytes > total_remaining_bytes) |
125 | num_bytes = total_remaining_bytes; | |
126 | if (pos < offset) { | |
7a3f595c | 127 | /* remaining zeros to write, up to destination offset */ |
684a3ff7 | 128 | loff_t total_remaining_zeros = (offset - pos); |
da0102a1 MH |
129 | |
130 | if (num_bytes > total_remaining_zeros) | |
131 | num_bytes = total_remaining_zeros; | |
132 | } | |
02bd9799 | 133 | ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, |
16a72c45 | 134 | ecryptfs_page_idx); |
da0102a1 MH |
135 | if (IS_ERR(ecryptfs_page)) { |
136 | rc = PTR_ERR(ecryptfs_page); | |
137 | printk(KERN_ERR "%s: Error getting page at " | |
138 | "index [%ld] from eCryptfs inode " | |
18d1dbf1 | 139 | "mapping; rc = [%d]\n", __func__, |
da0102a1 MH |
140 | ecryptfs_page_idx, rc); |
141 | goto out; | |
142 | } | |
465c9343 | 143 | ecryptfs_page_virt = kmap_atomic(ecryptfs_page); |
7a3f595c ES |
144 | |
145 | /* | |
146 | * pos: where we're now writing, offset: where the request was | |
147 | * If current pos is before request, we are filling zeros | |
148 | * If we are at or beyond request, we are writing the *data* | |
149 | * If we're in a fresh page beyond eof, zero it in either case | |
150 | */ | |
151 | if (pos < offset || !start_offset_in_page) { | |
152 | /* We are extending past the previous end of the file. | |
153 | * Fill in zero values to the end of the page */ | |
154 | memset(((char *)ecryptfs_page_virt | |
155 | + start_offset_in_page), 0, | |
09cbfeaf | 156 | PAGE_SIZE - start_offset_in_page); |
7a3f595c ES |
157 | } |
158 | ||
159 | /* pos >= offset, we are now writing the data request */ | |
da0102a1 MH |
160 | if (pos >= offset) { |
161 | memcpy(((char *)ecryptfs_page_virt | |
162 | + start_offset_in_page), | |
163 | (data + data_offset), num_bytes); | |
164 | data_offset += num_bytes; | |
da0102a1 | 165 | } |
465c9343 | 166 | kunmap_atomic(ecryptfs_page_virt); |
da0102a1 | 167 | flush_dcache_page(ecryptfs_page); |
16a72c45 MH |
168 | SetPageUptodate(ecryptfs_page); |
169 | unlock_page(ecryptfs_page); | |
13a791b4 TH |
170 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) |
171 | rc = ecryptfs_encrypt_page(ecryptfs_page); | |
172 | else | |
173 | rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, | |
174 | ecryptfs_page, | |
175 | start_offset_in_page, | |
176 | data_offset); | |
09cbfeaf | 177 | put_page(ecryptfs_page); |
da0102a1 MH |
178 | if (rc) { |
179 | printk(KERN_ERR "%s: Error encrypting " | |
18d1dbf1 | 180 | "page; rc = [%d]\n", __func__, rc); |
da0102a1 MH |
181 | goto out; |
182 | } | |
da0102a1 MH |
183 | pos += num_bytes; |
184 | } | |
5e6f0d76 TH |
185 | if (pos > ecryptfs_file_size) { |
186 | i_size_write(ecryptfs_inode, pos); | |
13a791b4 | 187 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { |
5e6f0d76 TH |
188 | int rc2; |
189 | ||
190 | rc2 = ecryptfs_write_inode_size_to_metadata( | |
13a791b4 | 191 | ecryptfs_inode); |
5e6f0d76 | 192 | if (rc2) { |
13a791b4 TH |
193 | printk(KERN_ERR "Problem with " |
194 | "ecryptfs_write_inode_size_to_metadata; " | |
5e6f0d76 TH |
195 | "rc = [%d]\n", rc2); |
196 | if (!rc) | |
197 | rc = rc2; | |
13a791b4 TH |
198 | goto out; |
199 | } | |
da0102a1 MH |
200 | } |
201 | } | |
202 | out: | |
203 | return rc; | |
204 | } | |
205 | ||
206 | /** | |
207 | * ecryptfs_read_lower | |
208 | * @data: The read data is stored here by this function | |
209 | * @offset: Byte offset in the lower file from which to read the data | |
210 | * @size: Number of bytes to read from @offset of the lower file and | |
211 | * store into @data | |
212 | * @ecryptfs_inode: The eCryptfs inode | |
213 | * | |
214 | * Read @size bytes of data at byte offset @offset from the lower | |
215 | * inode into memory location @data. | |
216 | * | |
96a7b9c2 | 217 | * Returns bytes read on success; 0 on EOF; less than zero on error |
da0102a1 MH |
218 | */ |
219 | int ecryptfs_read_lower(char *data, loff_t offset, size_t size, | |
220 | struct inode *ecryptfs_inode) | |
221 | { | |
f61500e0 | 222 | struct file *lower_file; |
f61500e0 TH |
223 | lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; |
224 | if (!lower_file) | |
225 | return -EIO; | |
bdd1d2d3 | 226 | return kernel_read(lower_file, data, size, &offset); |
da0102a1 MH |
227 | } |
228 | ||
229 | /** | |
230 | * ecryptfs_read_lower_page_segment | |
231 | * @page_for_ecryptfs: The page into which data for eCryptfs will be | |
232 | * written | |
09d02efa LJ |
233 | * @page_index: Page index in @page_for_ecryptfs from which to start |
234 | * writing | |
da0102a1 MH |
235 | * @offset_in_page: Offset in @page_for_ecryptfs from which to start |
236 | * writing | |
237 | * @size: The number of bytes to write into @page_for_ecryptfs | |
238 | * @ecryptfs_inode: The eCryptfs inode | |
239 | * | |
240 | * Determines the byte offset in the file for the given page and | |
241 | * offset within the page, maps the page, and makes the call to read | |
242 | * the contents of @page_for_ecryptfs from the lower inode. | |
243 | * | |
244 | * Returns zero on success; non-zero otherwise | |
245 | */ | |
246 | int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, | |
247 | pgoff_t page_index, | |
248 | size_t offset_in_page, size_t size, | |
249 | struct inode *ecryptfs_inode) | |
250 | { | |
251 | char *virt; | |
252 | loff_t offset; | |
253 | int rc; | |
254 | ||
09cbfeaf | 255 | offset = ((((loff_t)page_index) << PAGE_SHIFT) + offset_in_page); |
da0102a1 MH |
256 | virt = kmap(page_for_ecryptfs); |
257 | rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); | |
96a7b9c2 TH |
258 | if (rc > 0) |
259 | rc = 0; | |
da0102a1 | 260 | kunmap(page_for_ecryptfs); |
16a72c45 | 261 | flush_dcache_page(page_for_ecryptfs); |
da0102a1 MH |
262 | return rc; |
263 | } |