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/skcipher.h>
19 #include <keys/encrypted-type.h>
20 #include <keys/user-type.h>
21 #include <linux/gfp.h>
22 #include <linux/kernel.h>
23 #include <linux/key.h>
24 #include <linux/list.h>
25 #include <linux/mempool.h>
26 #include <linux/random.h>
27 #include <linux/scatterlist.h>
28 #include <linux/spinlock_types.h>
29 #include <linux/f2fs_fs.h>
30 #include <linux/ratelimit.h>
33 #include "f2fs_crypto.h"
37 * f2fs_dir_crypt_complete() -
39 static void f2fs_dir_crypt_complete(struct crypto_async_request *req, int res)
41 struct f2fs_completion_result *ecr = req->data;
43 if (res == -EINPROGRESS)
46 complete(&ecr->completion);
49 bool f2fs_valid_filenames_enc_mode(uint32_t mode)
51 return (mode == F2FS_ENCRYPTION_MODE_AES_256_CTS);
54 static unsigned max_name_len(struct inode *inode)
56 return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
61 * f2fs_fname_encrypt() -
63 * This function encrypts the input filename, and returns the length of the
64 * ciphertext. Errors are returned as negative numbers. We trust the caller to
65 * allocate sufficient memory to oname string.
67 static int f2fs_fname_encrypt(struct inode *inode,
68 const struct qstr *iname, struct f2fs_str *oname)
71 struct skcipher_request *req = NULL;
72 DECLARE_F2FS_COMPLETION_RESULT(ecr);
73 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
74 struct crypto_skcipher *tfm = ci->ci_ctfm;
76 char iv[F2FS_CRYPTO_BLOCK_SIZE];
77 struct scatterlist src_sg, dst_sg;
78 int padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
79 char *workbuf, buf[32], *alloc_buf = NULL;
80 unsigned lim = max_name_len(inode);
82 if (iname->len <= 0 || iname->len > lim)
85 ciphertext_len = (iname->len < F2FS_CRYPTO_BLOCK_SIZE) ?
86 F2FS_CRYPTO_BLOCK_SIZE : iname->len;
87 ciphertext_len = f2fs_fname_crypto_round_up(ciphertext_len, padding);
88 ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len;
90 if (ciphertext_len <= sizeof(buf)) {
93 alloc_buf = kmalloc(ciphertext_len, GFP_NOFS);
99 /* Allocate request */
100 req = skcipher_request_alloc(tfm, GFP_NOFS);
102 printk_ratelimited(KERN_ERR
103 "%s: crypto_request_alloc() failed\n", __func__);
107 skcipher_request_set_callback(req,
108 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
109 f2fs_dir_crypt_complete, &ecr);
112 memcpy(workbuf, iname->name, iname->len);
113 if (iname->len < ciphertext_len)
114 memset(workbuf + iname->len, 0, ciphertext_len - iname->len);
117 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
119 /* Create encryption request */
120 sg_init_one(&src_sg, workbuf, ciphertext_len);
121 sg_init_one(&dst_sg, oname->name, ciphertext_len);
122 skcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv);
123 res = crypto_skcipher_encrypt(req);
124 if (res == -EINPROGRESS || res == -EBUSY) {
125 BUG_ON(req->base.data != &ecr);
126 wait_for_completion(&ecr.completion);
130 skcipher_request_free(req);
132 printk_ratelimited(KERN_ERR
133 "%s: Error (error code %d)\n", __func__, res);
135 oname->len = ciphertext_len;
140 * f2fs_fname_decrypt()
141 * This function decrypts the input filename, and returns
142 * the length of the plaintext.
143 * Errors are returned as negative numbers.
144 * We trust the caller to allocate sufficient memory to oname string.
146 static int f2fs_fname_decrypt(struct inode *inode,
147 const struct f2fs_str *iname, struct f2fs_str *oname)
149 struct skcipher_request *req = NULL;
150 DECLARE_F2FS_COMPLETION_RESULT(ecr);
151 struct scatterlist src_sg, dst_sg;
152 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
153 struct crypto_skcipher *tfm = ci->ci_ctfm;
155 char iv[F2FS_CRYPTO_BLOCK_SIZE];
156 unsigned lim = max_name_len(inode);
158 if (iname->len <= 0 || iname->len > lim)
161 /* Allocate request */
162 req = skcipher_request_alloc(tfm, GFP_NOFS);
164 printk_ratelimited(KERN_ERR
165 "%s: crypto_request_alloc() failed\n", __func__);
168 skcipher_request_set_callback(req,
169 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
170 f2fs_dir_crypt_complete, &ecr);
173 memset(iv, 0, F2FS_CRYPTO_BLOCK_SIZE);
175 /* Create decryption request */
176 sg_init_one(&src_sg, iname->name, iname->len);
177 sg_init_one(&dst_sg, oname->name, oname->len);
178 skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv);
179 res = crypto_skcipher_decrypt(req);
180 if (res == -EINPROGRESS || res == -EBUSY) {
181 BUG_ON(req->base.data != &ecr);
182 wait_for_completion(&ecr.completion);
185 skcipher_request_free(req);
187 printk_ratelimited(KERN_ERR
188 "%s: Error in f2fs_fname_decrypt (error code %d)\n",
193 oname->len = strnlen(oname->name, iname->len);
197 static const char *lookup_table =
198 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
201 * f2fs_fname_encode_digest() -
203 * Encodes the input digest using characters from the set [a-zA-Z0-9_+].
204 * The encoded string is roughly 4/3 times the size of the input string.
206 static int digest_encode(const char *src, int len, char *dst)
208 int i = 0, bits = 0, ac = 0;
212 ac += (((unsigned char) src[i]) << bits);
215 *cp++ = lookup_table[ac & 0x3f];
222 *cp++ = lookup_table[ac & 0x3f];
226 static int digest_decode(const char *src, int len, char *dst)
228 int i = 0, bits = 0, ac = 0;
233 p = strchr(lookup_table, src[i]);
234 if (p == NULL || src[i] == 0)
236 ac += (p - lookup_table) << bits;
251 * f2fs_fname_crypto_round_up() -
253 * Return: The next multiple of block size
255 u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize)
257 return ((size + blksize - 1) / blksize) * blksize;
261 * f2fs_fname_crypto_alloc_obuff() -
263 * Allocates an output buffer that is sufficient for the crypto operation
264 * specified by the context and the direction.
266 int f2fs_fname_crypto_alloc_buffer(struct inode *inode,
267 u32 ilen, struct f2fs_str *crypto_str)
271 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
274 padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
275 if (padding < F2FS_CRYPTO_BLOCK_SIZE)
276 padding = F2FS_CRYPTO_BLOCK_SIZE;
277 olen = f2fs_fname_crypto_round_up(ilen, padding);
278 crypto_str->len = olen;
279 if (olen < F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
280 olen = F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
281 /* Allocated buffer can hold one more character to null-terminate the
283 crypto_str->name = kmalloc(olen + 1, GFP_NOFS);
284 if (!(crypto_str->name))
290 * f2fs_fname_crypto_free_buffer() -
292 * Frees the buffer allocated for crypto operation.
294 void f2fs_fname_crypto_free_buffer(struct f2fs_str *crypto_str)
298 kfree(crypto_str->name);
299 crypto_str->name = NULL;
303 * f2fs_fname_disk_to_usr() - converts a filename from disk space to user space
305 int f2fs_fname_disk_to_usr(struct inode *inode,
307 const struct f2fs_str *iname,
308 struct f2fs_str *oname)
310 const struct qstr qname = FSTR_TO_QSTR(iname);
314 if (is_dot_dotdot(&qname)) {
315 oname->name[0] = '.';
316 oname->name[iname->len - 1] = '.';
317 oname->len = iname->len;
321 if (F2FS_I(inode)->i_crypt_info)
322 return f2fs_fname_decrypt(inode, iname, oname);
324 if (iname->len <= F2FS_FNAME_CRYPTO_DIGEST_SIZE) {
325 ret = digest_encode(iname->name, iname->len, oname->name);
330 memcpy(buf, hash, 4);
331 memset(buf + 4, 0, 4);
334 memcpy(buf + 8, iname->name + iname->len - 16, 16);
335 oname->name[0] = '_';
336 ret = digest_encode(buf, 24, oname->name + 1);
337 oname->len = ret + 1;
342 * f2fs_fname_usr_to_disk() - converts a filename from user space to disk space
344 int f2fs_fname_usr_to_disk(struct inode *inode,
345 const struct qstr *iname,
346 struct f2fs_str *oname)
349 struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
351 if (is_dot_dotdot(iname)) {
352 oname->name[0] = '.';
353 oname->name[iname->len - 1] = '.';
354 oname->len = iname->len;
359 res = f2fs_fname_encrypt(inode, iname, oname);
362 /* Without a proper key, a user is not allowed to modify the filenames
363 * in a directory. Consequently, a user space name cannot be mapped to
364 * a disk-space name */
368 int f2fs_fname_setup_filename(struct inode *dir, const struct qstr *iname,
369 int lookup, struct f2fs_filename *fname)
371 struct f2fs_crypt_info *ci;
372 int ret = 0, bigname = 0;
374 memset(fname, 0, sizeof(struct f2fs_filename));
375 fname->usr_fname = iname;
377 if (!f2fs_encrypted_inode(dir) || is_dot_dotdot(iname)) {
378 fname->disk_name.name = (unsigned char *)iname->name;
379 fname->disk_name.len = iname->len;
382 ret = f2fs_get_encryption_info(dir);
385 ci = F2FS_I(dir)->i_crypt_info;
387 ret = f2fs_fname_crypto_alloc_buffer(dir, iname->len,
391 ret = f2fs_fname_encrypt(dir, iname, &fname->crypto_buf);
394 fname->disk_name.name = fname->crypto_buf.name;
395 fname->disk_name.len = fname->crypto_buf.len;
401 /* We don't have the key and we are doing a lookup; decode the
404 if (iname->name[0] == '_')
406 if ((bigname && (iname->len != 33)) ||
407 (!bigname && (iname->len > 43)))
410 fname->crypto_buf.name = kmalloc(32, GFP_KERNEL);
411 if (fname->crypto_buf.name == NULL)
413 ret = digest_decode(iname->name + bigname, iname->len - bigname,
414 fname->crypto_buf.name);
419 fname->crypto_buf.len = ret;
421 memcpy(&fname->hash, fname->crypto_buf.name, 4);
423 fname->disk_name.name = fname->crypto_buf.name;
424 fname->disk_name.len = fname->crypto_buf.len;
428 f2fs_fname_crypto_free_buffer(&fname->crypto_buf);
432 void f2fs_fname_free_filename(struct f2fs_filename *fname)
434 kfree(fname->crypto_buf.name);
435 fname->crypto_buf.name = NULL;
436 fname->usr_fname = NULL;
437 fname->disk_name.name = NULL;