2 * linux/fs/f2fs/crypto_fname.c
4 * Copied from linux/fs/ext4/crypto.c
6 * Copyright (C) 2015, Google, Inc.
7 * Copyright (C) 2015, Motorola Mobility
9 * This contains functions for filename crypto management in f2fs
11 * Written by Uday Savagaonkar, 2014.
13 * Adjust f2fs dentry structure
16 * This has not yet undergone a rigorous security audit.
18 #include <crypto/hash.h>
19 #include <crypto/sha.h>
20 #include <keys/encrypted-type.h>
21 #include <keys/user-type.h>
22 #include <linux/crypto.h>
23 #include <linux/gfp.h>
24 #include <linux/kernel.h>
25 #include <linux/key.h>
26 #include <linux/list.h>
27 #include <linux/mempool.h>
28 #include <linux/random.h>
29 #include <linux/scatterlist.h>
30 #include <linux/spinlock_types.h>
31 #include <linux/f2fs_fs.h>
32 #include <linux/ratelimit.h>
35 #include "f2fs_crypto.h"
39 * f2fs_dir_crypt_complete() -
41 static void f2fs_dir_crypt_complete(struct crypto_async_request *req, int res)
43 struct f2fs_completion_result *ecr = req->data;
45 if (res == -EINPROGRESS)
48 complete(&ecr->completion);
51 bool f2fs_valid_filenames_enc_mode(uint32_t mode)
53 return (mode == F2FS_ENCRYPTION_MODE_AES_256_CTS);
56 static unsigned max_name_len(struct inode *inode)
58 return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
63 * f2fs_fname_encrypt() -
65 * This function encrypts the input filename, and returns the length of the
66 * ciphertext. Errors are returned as negative numbers. We trust the caller to
67 * allocate sufficient memory to oname string.
69 static int f2fs_fname_encrypt(struct inode *inode,
70 const struct qstr *iname, struct f2fs_str *oname)
73 struct ablkcipher_request *req = NULL;
74 DECLARE_F2FS_COMPLETION_RESULT(ecr);
75 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
76 struct crypto_ablkcipher *tfm = ci->ci_ctfm;
78 char iv[F2FS_CRYPTO_BLOCK_SIZE];
79 struct scatterlist src_sg, dst_sg;
80 int padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
81 char *workbuf, buf[32], *alloc_buf = NULL;
82 unsigned lim = max_name_len(inode);
84 if (iname->len <= 0 || iname->len > lim)
87 ciphertext_len = (iname->len < F2FS_CRYPTO_BLOCK_SIZE) ?
88 F2FS_CRYPTO_BLOCK_SIZE : iname->len;
89 ciphertext_len = f2fs_fname_crypto_round_up(ciphertext_len, padding);
90 ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
92 if (ciphertext_len <= sizeof(buf)) {
95 alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
101 /* Allocate request */
102 req = ablkcipher_request_alloc(tfm, GFP_NOFS);
104 printk_ratelimited(KERN_ERR
105 "%s: crypto_request_alloc() failed\n", __func__);
109 ablkcipher_request_set_callback(req,
110 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
111 f2fs_dir_crypt_complete, &ecr);
114 memcpy(workbuf, iname->name, iname->len);
115 if (iname->len < ciphertext_len)
116 memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
119 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
121 /* Create encryption request */
122 sg_init_one(&src_sg, workbuf, ciphertext_len);
123 sg_init_one(&dst_sg, oname->name, ciphertext_len);
124 ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
125 res = crypto_ablkcipher_encrypt(req);
126 if (res == -EINPROGRESS || res == -EBUSY) {
127 BUG_ON(req->base.data != &ecr);
128 wait_for_completion(&ecr.completion);
132 ablkcipher_request_free(req);
134 printk_ratelimited(KERN_ERR
135 "%s: Error (error code %d)\n", __func__, res);
137 oname->len = ciphertext_len;
142 * f2fs_fname_decrypt()
143 * This function decrypts the input filename, and returns
144 * the length of the plaintext.
145 * Errors are returned as negative numbers.
146 * We trust the caller to allocate sufficient memory to oname string.
148 static int f2fs_fname_decrypt(struct inode *inode,
149 const struct f2fs_str *iname, struct f2fs_str *oname)
151 struct ablkcipher_request *req = NULL;
152 DECLARE_F2FS_COMPLETION_RESULT(ecr);
153 struct scatterlist src_sg, dst_sg;
154 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
155 struct crypto_ablkcipher *tfm = ci->ci_ctfm;
157 char iv[F2FS_CRYPTO_BLOCK_SIZE];
158 unsigned lim = max_name_len(inode);
160 if (iname->len <= 0 || iname->len > lim)
163 /* Allocate request */
164 req = ablkcipher_request_alloc(tfm, GFP_NOFS);
166 printk_ratelimited(KERN_ERR
167 "%s: crypto_request_alloc() failed\n", __func__);
170 ablkcipher_request_set_callback(req,
171 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
172 f2fs_dir_crypt_complete, &ecr);
175 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
177 /* Create decryption request */
178 sg_init_one(&src_sg, iname->name, iname->len);
179 sg_init_one(&dst_sg, oname->name, oname->len);
180 ablkcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
181 res = crypto_ablkcipher_decrypt(req);
182 if (res == -EINPROGRESS || res == -EBUSY) {
183 BUG_ON(req->base.data != &ecr);
184 wait_for_completion(&ecr.completion);
187 ablkcipher_request_free(req);
189 printk_ratelimited(KERN_ERR
190 "%s: Error in f2fs_fname_decrypt (error code %d)\n",
195 oname->len = strnlen(oname->name, iname->len);
199 static const char *lookup_table =
200 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
203 * f2fs_fname_encode_digest() -
205 * Encodes the input digest using characters from the set [a-zA-Z0-9_+].
206 * The encoded string is roughly 4/3 times the size of the input string.
208 static int digest_encode(const char *src, int len, char *dst)
210 int i = 0, bits = 0, ac = 0;
214 ac += (((unsigned char) src[i]) << bits);
217 *cp++ = lookup_table[ac & 0x3f];
224 *cp++ = lookup_table[ac & 0x3f];
228 static int digest_decode(const char *src, int len, char *dst)
230 int i = 0, bits = 0, ac = 0;
235 p = strchr(lookup_table, src[i]);
236 if (p == NULL || src[i] == 0)
238 ac += (p - lookup_table) << bits;
253 * f2fs_fname_crypto_round_up() -
255 * Return: The next multiple of block size
257 u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize)
259 return ((size + blksize - 1) / blksize) * blksize;
263 * f2fs_fname_crypto_alloc_obuff() -
265 * Allocates an output buffer that is sufficient for the crypto operation
266 * specified by the context and the direction.
268 int f2fs_fname_crypto_alloc_buffer(struct inode *inode,
269 u32 ilen, struct f2fs_str *crypto_str)
273 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
276 padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
277 if (padding < F2FS_CRYPTO_BLOCK_SIZE)
278 padding = F2FS_CRYPTO_BLOCK_SIZE;
279 olen = f2fs_fname_crypto_round_up(ilen, padding);
280 crypto_str->len = olen;
281 if (olen < F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
282 olen = F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
283 /* Allocated buffer can hold one more character to null-terminate the
285 crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
286 if (!(crypto_str->name))
292 * f2fs_fname_crypto_free_buffer() -
294 * Frees the buffer allocated for crypto operation.
296 void f2fs_fname_crypto_free_buffer(struct f2fs_str *crypto_str)
300 kfree(crypto_str->name);
301 crypto_str->name = NULL;
305 * f2fs_fname_disk_to_usr() - converts a filename from disk space to user space
307 int f2fs_fname_disk_to_usr(struct inode *inode,
309 const struct f2fs_str *iname,
310 struct f2fs_str *oname)
312 const struct qstr qname = FSTR_TO_QSTR(iname);
316 if (is_dot_dotdot(&qname)) {
317 oname->name[0] = '.';
318 oname->name[iname->len - 1] = '.';
319 oname->len = iname->len;
323 if (F2FS_I(inode)->i_crypt_info)
324 return f2fs_fname_decrypt(inode, iname, oname);
326 if (iname->len <= F2FS_FNAME_CRYPTO_DIGEST_SIZE) {
327 ret = digest_encode(iname->name, iname->len, oname->name);
332 memcpy(buf, hash, 4);
333 memset(buf + 4, 0, 4);
336 memcpy(buf + 8, iname->name + iname->len - 16, 16);
337 oname->name[0] = '_';
338 ret = digest_encode(buf, 24, oname->name + 1);
339 oname->len = ret + 1;
344 * f2fs_fname_usr_to_disk() - converts a filename from user space to disk space
346 int f2fs_fname_usr_to_disk(struct inode *inode,
347 const struct qstr *iname,
348 struct f2fs_str *oname)
351 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
353 if (is_dot_dotdot(iname)) {
354 oname->name[0] = '.';
355 oname->name[iname->len - 1] = '.';
356 oname->len = iname->len;
361 res = f2fs_fname_encrypt(inode, iname, oname);
364 /* Without a proper key, a user is not allowed to modify the filenames
365 * in a directory. Consequently, a user space name cannot be mapped to
366 * a disk-space name */
370 int f2fs_fname_setup_filename(struct inode *dir, const struct qstr *iname,
371 int lookup, struct f2fs_filename *fname)
373 struct f2fs_crypt_info *ci;
374 int ret = 0, bigname = 0;
376 memset(fname, 0, sizeof(struct f2fs_filename));
377 fname->usr_fname = iname;
379 if (!f2fs_encrypted_inode(dir) || is_dot_dotdot(iname)) {
380 fname->disk_name.name = (unsigned char *)iname->name;
381 fname->disk_name.len = iname->len;
384 ret = f2fs_get_encryption_info(dir);
387 ci = F2FS_I(dir)->i_crypt_info;
389 ret = f2fs_fname_crypto_alloc_buffer(dir, iname->len,
393 ret = f2fs_fname_encrypt(dir, iname, &fname->crypto_buf);
396 fname->disk_name.name = fname->crypto_buf.name;
397 fname->disk_name.len = fname->crypto_buf.len;
403 /* We don't have the key and we are doing a lookup; decode the
406 if (iname->name[0] == '_')
408 if ((bigname && (iname->len != 33)) ||
409 (!bigname && (iname->len > 43)))
412 fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
413 if (fname->crypto_buf.name == NULL)
415 ret = digest_decode(iname->name + bigname, iname->len - bigname,
416 fname->crypto_buf.name);
421 fname->crypto_buf.len = ret;
423 memcpy(&fname->hash, fname->crypto_buf.name, 4);
425 fname->disk_name.name = fname->crypto_buf.name;
426 fname->disk_name.len = fname->crypto_buf.len;
430 f2fs_fname_crypto_free_buffer(&fname->crypto_buf);
434 void f2fs_fname_free_filename(struct f2fs_filename *fname)
436 kfree(fname->crypto_buf.name);
437 fname->crypto_buf.name = NULL;
438 fname->usr_fname = NULL;
439 fname->disk_name.name = NULL;