1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
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> |
7 | */ |
8 | |
9 | #include <linux/fs.h> |
10 | #include <linux/pagemap.h> |
11 | #include <linux/sched/signal.h> |
12 | |
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 | * |
25 | * Returns bytes written on success; less than zero on error |
26 | */ |
27 | int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, |
28 | loff_t offset, size_t size) |
29 | { |
30 | struct file *lower_file; |
31 | ssize_t rc; |
32 | |
33 | lower_file = ecryptfs_inode_to_private(inode: ecryptfs_inode)->lower_file; |
34 | if (!lower_file) |
35 | return -EIO; |
36 | rc = kernel_write(lower_file, data, size, &offset); |
37 | mark_inode_dirty_sync(inode: 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 | |
65 | offset = ((((loff_t)page_for_lower->index) << PAGE_SHIFT) |
66 | + offset_in_page); |
67 | virt = kmap_local_page(page: page_for_lower); |
68 | rc = ecryptfs_write_lower(ecryptfs_inode, data: virt, offset, size); |
69 | if (rc > 0) |
70 | rc = 0; |
71 | kunmap_local(virt); |
72 | return rc; |
73 | } |
74 | |
75 | /** |
76 | * ecryptfs_write |
77 | * @ecryptfs_inode: The eCryptfs file into which to write |
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 | */ |
93 | int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, |
94 | size_t size) |
95 | { |
96 | struct page *ecryptfs_page; |
97 | struct ecryptfs_crypt_stat *crypt_stat; |
98 | char *ecryptfs_page_virt; |
99 | loff_t ecryptfs_file_size = i_size_read(inode: ecryptfs_inode); |
100 | loff_t data_offset = 0; |
101 | loff_t pos; |
102 | int rc = 0; |
103 | |
104 | crypt_stat = &ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat; |
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 | */ |
109 | if (offset > ecryptfs_file_size) |
110 | pos = ecryptfs_file_size; |
111 | else |
112 | pos = offset; |
113 | while (pos < (offset + size)) { |
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); |
117 | loff_t total_remaining_bytes = ((offset + size) - pos); |
118 | |
119 | if (fatal_signal_pending(current)) { |
120 | rc = -EINTR; |
121 | break; |
122 | } |
123 | |
124 | if (num_bytes > total_remaining_bytes) |
125 | num_bytes = total_remaining_bytes; |
126 | if (pos < offset) { |
127 | /* remaining zeros to write, up to destination offset */ |
128 | loff_t total_remaining_zeros = (offset - pos); |
129 | |
130 | if (num_bytes > total_remaining_zeros) |
131 | num_bytes = total_remaining_zeros; |
132 | } |
133 | ecryptfs_page = ecryptfs_get_locked_page(inode: ecryptfs_inode, |
134 | index: ecryptfs_page_idx); |
135 | if (IS_ERR(ptr: ecryptfs_page)) { |
136 | rc = PTR_ERR(ptr: ecryptfs_page); |
137 | printk(KERN_ERR "%s: Error getting page at " |
138 | "index [%ld] from eCryptfs inode " |
139 | "mapping; rc = [%d]\n" , __func__, |
140 | ecryptfs_page_idx, rc); |
141 | goto out; |
142 | } |
143 | ecryptfs_page_virt = kmap_local_page(page: ecryptfs_page); |
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, |
156 | PAGE_SIZE - start_offset_in_page); |
157 | } |
158 | |
159 | /* pos >= offset, we are now writing the data request */ |
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; |
165 | } |
166 | kunmap_local(ecryptfs_page_virt); |
167 | flush_dcache_page(page: ecryptfs_page); |
168 | SetPageUptodate(ecryptfs_page); |
169 | unlock_page(page: ecryptfs_page); |
170 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) |
171 | rc = ecryptfs_encrypt_page(page: ecryptfs_page); |
172 | else |
173 | rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, |
174 | page_for_lower: ecryptfs_page, |
175 | offset_in_page: start_offset_in_page, |
176 | size: data_offset); |
177 | put_page(page: ecryptfs_page); |
178 | if (rc) { |
179 | printk(KERN_ERR "%s: Error encrypting " |
180 | "page; rc = [%d]\n" , __func__, rc); |
181 | goto out; |
182 | } |
183 | pos += num_bytes; |
184 | } |
185 | if (pos > ecryptfs_file_size) { |
186 | i_size_write(inode: ecryptfs_inode, i_size: pos); |
187 | if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { |
188 | int rc2; |
189 | |
190 | rc2 = ecryptfs_write_inode_size_to_metadata( |
191 | ecryptfs_inode); |
192 | if (rc2) { |
193 | printk(KERN_ERR "Problem with " |
194 | "ecryptfs_write_inode_size_to_metadata; " |
195 | "rc = [%d]\n" , rc2); |
196 | if (!rc) |
197 | rc = rc2; |
198 | goto out; |
199 | } |
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 | * |
217 | * Returns bytes read on success; 0 on EOF; less than zero on error |
218 | */ |
219 | int ecryptfs_read_lower(char *data, loff_t offset, size_t size, |
220 | struct inode *ecryptfs_inode) |
221 | { |
222 | struct file *lower_file; |
223 | lower_file = ecryptfs_inode_to_private(inode: ecryptfs_inode)->lower_file; |
224 | if (!lower_file) |
225 | return -EIO; |
226 | return kernel_read(lower_file, data, size, &offset); |
227 | } |
228 | |
229 | /** |
230 | * ecryptfs_read_lower_page_segment |
231 | * @page_for_ecryptfs: The page into which data for eCryptfs will be |
232 | * written |
233 | * @page_index: Page index in @page_for_ecryptfs from which to start |
234 | * writing |
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 | |
255 | offset = ((((loff_t)page_index) << PAGE_SHIFT) + offset_in_page); |
256 | virt = kmap_local_page(page: page_for_ecryptfs); |
257 | rc = ecryptfs_read_lower(data: virt, offset, size, ecryptfs_inode); |
258 | if (rc > 0) |
259 | rc = 0; |
260 | kunmap_local(virt); |
261 | flush_dcache_page(page: page_for_ecryptfs); |
262 | return rc; |
263 | } |
264 | |