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14#include <linux/scatterlist.h>
15#include <crypto/skcipher.h>
16#include "fscrypt_private.h"
17
18static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
19{
20 if (str->len == 1 && str->name[0] == '.')
21 return true;
22
23 if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
24 return true;
25
26 return false;
27}
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36
37int fname_encrypt(struct inode *inode, const struct qstr *iname,
38 u8 *out, unsigned int olen)
39{
40 struct skcipher_request *req = NULL;
41 DECLARE_CRYPTO_WAIT(wait);
42 struct fscrypt_info *ci = inode->i_crypt_info;
43 struct crypto_skcipher *tfm = ci->ci_ctfm;
44 union fscrypt_iv iv;
45 struct scatterlist sg;
46 int res;
47
48
49
50
51
52 if (WARN_ON(olen < iname->len))
53 return -ENOBUFS;
54 memcpy(out, iname->name, iname->len);
55 memset(out + iname->len, 0, olen - iname->len);
56
57
58 fscrypt_generate_iv(&iv, 0, ci);
59
60
61 req = skcipher_request_alloc(tfm, GFP_NOFS);
62 if (!req)
63 return -ENOMEM;
64 skcipher_request_set_callback(req,
65 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
66 crypto_req_done, &wait);
67 sg_init_one(&sg, out, olen);
68 skcipher_request_set_crypt(req, &sg, &sg, olen, &iv);
69
70
71 res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
72 skcipher_request_free(req);
73 if (res < 0) {
74 fscrypt_err(inode->i_sb,
75 "Filename encryption failed for inode %lu: %d",
76 inode->i_ino, res);
77 return res;
78 }
79
80 return 0;
81}
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89
90static int fname_decrypt(struct inode *inode,
91 const struct fscrypt_str *iname,
92 struct fscrypt_str *oname)
93{
94 struct skcipher_request *req = NULL;
95 DECLARE_CRYPTO_WAIT(wait);
96 struct scatterlist src_sg, dst_sg;
97 struct fscrypt_info *ci = inode->i_crypt_info;
98 struct crypto_skcipher *tfm = ci->ci_ctfm;
99 union fscrypt_iv iv;
100 int res;
101
102
103 req = skcipher_request_alloc(tfm, GFP_NOFS);
104 if (!req)
105 return -ENOMEM;
106 skcipher_request_set_callback(req,
107 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
108 crypto_req_done, &wait);
109
110
111 fscrypt_generate_iv(&iv, 0, ci);
112
113
114 sg_init_one(&src_sg, iname->name, iname->len);
115 sg_init_one(&dst_sg, oname->name, oname->len);
116 skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv);
117 res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
118 skcipher_request_free(req);
119 if (res < 0) {
120 fscrypt_err(inode->i_sb,
121 "Filename decryption failed for inode %lu: %d",
122 inode->i_ino, res);
123 return res;
124 }
125
126 oname->len = strnlen(oname->name, iname->len);
127 return 0;
128}
129
130static const char *lookup_table =
131 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
132
133#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
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140
141static int digest_encode(const char *src, int len, char *dst)
142{
143 int i = 0, bits = 0, ac = 0;
144 char *cp = dst;
145
146 while (i < len) {
147 ac += (((unsigned char) src[i]) << bits);
148 bits += 8;
149 do {
150 *cp++ = lookup_table[ac & 0x3f];
151 ac >>= 6;
152 bits -= 6;
153 } while (bits >= 6);
154 i++;
155 }
156 if (bits)
157 *cp++ = lookup_table[ac & 0x3f];
158 return cp - dst;
159}
160
161static int digest_decode(const char *src, int len, char *dst)
162{
163 int i = 0, bits = 0, ac = 0;
164 const char *p;
165 char *cp = dst;
166
167 while (i < len) {
168 p = strchr(lookup_table, src[i]);
169 if (p == NULL || src[i] == 0)
170 return -2;
171 ac += (p - lookup_table) << bits;
172 bits += 6;
173 if (bits >= 8) {
174 *cp++ = ac & 0xff;
175 ac >>= 8;
176 bits -= 8;
177 }
178 i++;
179 }
180 if (ac)
181 return -1;
182 return cp - dst;
183}
184
185bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
186 u32 max_len, u32 *encrypted_len_ret)
187{
188 int padding = 4 << (inode->i_crypt_info->ci_flags &
189 FS_POLICY_FLAGS_PAD_MASK);
190 u32 encrypted_len;
191
192 if (orig_len > max_len)
193 return false;
194 encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE);
195 encrypted_len = round_up(encrypted_len, padding);
196 *encrypted_len_ret = min(encrypted_len, max_len);
197 return true;
198}
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207
208int fscrypt_fname_alloc_buffer(const struct inode *inode,
209 u32 max_encrypted_len,
210 struct fscrypt_str *crypto_str)
211{
212 const u32 max_encoded_len =
213 max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE),
214 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)));
215 u32 max_presented_len;
216
217 max_presented_len = max(max_encoded_len, max_encrypted_len);
218
219 crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS);
220 if (!crypto_str->name)
221 return -ENOMEM;
222 crypto_str->len = max_presented_len;
223 return 0;
224}
225EXPORT_SYMBOL(fscrypt_fname_alloc_buffer);
226
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230
231
232void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
233{
234 if (!crypto_str)
235 return;
236 kfree(crypto_str->name);
237 crypto_str->name = NULL;
238}
239EXPORT_SYMBOL(fscrypt_fname_free_buffer);
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253int fscrypt_fname_disk_to_usr(struct inode *inode,
254 u32 hash, u32 minor_hash,
255 const struct fscrypt_str *iname,
256 struct fscrypt_str *oname)
257{
258 const struct qstr qname = FSTR_TO_QSTR(iname);
259 struct fscrypt_digested_name digested_name;
260
261 if (fscrypt_is_dot_dotdot(&qname)) {
262 oname->name[0] = '.';
263 oname->name[iname->len - 1] = '.';
264 oname->len = iname->len;
265 return 0;
266 }
267
268 if (iname->len < FS_CRYPTO_BLOCK_SIZE)
269 return -EUCLEAN;
270
271 if (fscrypt_has_encryption_key(inode))
272 return fname_decrypt(inode, iname, oname);
273
274 if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) {
275 oname->len = digest_encode(iname->name, iname->len,
276 oname->name);
277 return 0;
278 }
279 if (hash) {
280 digested_name.hash = hash;
281 digested_name.minor_hash = minor_hash;
282 } else {
283 digested_name.hash = 0;
284 digested_name.minor_hash = 0;
285 }
286 memcpy(digested_name.digest,
287 FSCRYPT_FNAME_DIGEST(iname->name, iname->len),
288 FSCRYPT_FNAME_DIGEST_SIZE);
289 oname->name[0] = '_';
290 oname->len = 1 + digest_encode((const char *)&digested_name,
291 sizeof(digested_name), oname->name + 1);
292 return 0;
293}
294EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
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320int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
321 int lookup, struct fscrypt_name *fname)
322{
323 int ret;
324 int digested;
325
326 memset(fname, 0, sizeof(struct fscrypt_name));
327 fname->usr_fname = iname;
328
329 if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) {
330 fname->disk_name.name = (unsigned char *)iname->name;
331 fname->disk_name.len = iname->len;
332 return 0;
333 }
334 ret = fscrypt_get_encryption_info(dir);
335 if (ret)
336 return ret;
337
338 if (fscrypt_has_encryption_key(dir)) {
339 if (!fscrypt_fname_encrypted_size(dir, iname->len,
340 dir->i_sb->s_cop->max_namelen,
341 &fname->crypto_buf.len))
342 return -ENAMETOOLONG;
343 fname->crypto_buf.name = kmalloc(fname->crypto_buf.len,
344 GFP_NOFS);
345 if (!fname->crypto_buf.name)
346 return -ENOMEM;
347
348 ret = fname_encrypt(dir, iname, fname->crypto_buf.name,
349 fname->crypto_buf.len);
350 if (ret)
351 goto errout;
352 fname->disk_name.name = fname->crypto_buf.name;
353 fname->disk_name.len = fname->crypto_buf.len;
354 return 0;
355 }
356 if (!lookup)
357 return -ENOKEY;
358 fname->is_ciphertext_name = true;
359
360
361
362
363
364 if (iname->name[0] == '_') {
365 if (iname->len !=
366 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name)))
367 return -ENOENT;
368 digested = 1;
369 } else {
370 if (iname->len >
371 BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE))
372 return -ENOENT;
373 digested = 0;
374 }
375
376 fname->crypto_buf.name =
377 kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE,
378 sizeof(struct fscrypt_digested_name)),
379 GFP_KERNEL);
380 if (fname->crypto_buf.name == NULL)
381 return -ENOMEM;
382
383 ret = digest_decode(iname->name + digested, iname->len - digested,
384 fname->crypto_buf.name);
385 if (ret < 0) {
386 ret = -ENOENT;
387 goto errout;
388 }
389 fname->crypto_buf.len = ret;
390 if (digested) {
391 const struct fscrypt_digested_name *n =
392 (const void *)fname->crypto_buf.name;
393 fname->hash = n->hash;
394 fname->minor_hash = n->minor_hash;
395 } else {
396 fname->disk_name.name = fname->crypto_buf.name;
397 fname->disk_name.len = fname->crypto_buf.len;
398 }
399 return 0;
400
401errout:
402 kfree(fname->crypto_buf.name);
403 return ret;
404}
405EXPORT_SYMBOL(fscrypt_setup_filename);
406