Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 1 | /* |
| 2 | * This contains functions for filename crypto management |
| 3 | * |
| 4 | * Copyright (C) 2015, Google, Inc. |
| 5 | * Copyright (C) 2015, Motorola Mobility |
| 6 | * |
| 7 | * Written by Uday Savagaonkar, 2014. |
| 8 | * Modified by Jaegeuk Kim, 2015. |
| 9 | * |
| 10 | * This has not yet undergone a rigorous security audit. |
| 11 | */ |
| 12 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 13 | #include <linux/scatterlist.h> |
| 14 | #include <linux/ratelimit.h> |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 15 | #include "fscrypt_private.h" |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 16 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 17 | /** |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 18 | * fname_encrypt() - encrypt a filename |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 19 | * |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 20 | * The caller must have allocated sufficient memory for the @oname string. |
| 21 | * |
| 22 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 23 | */ |
| 24 | static int fname_encrypt(struct inode *inode, |
| 25 | const struct qstr *iname, struct fscrypt_str *oname) |
| 26 | { |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 27 | struct skcipher_request *req = NULL; |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 28 | DECLARE_CRYPTO_WAIT(wait); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 29 | struct fscrypt_info *ci = inode->i_crypt_info; |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 30 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 31 | int res = 0; |
| 32 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 33 | struct scatterlist sg; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 34 | int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 35 | unsigned int lim; |
| 36 | unsigned int cryptlen; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 37 | |
| 38 | lim = inode->i_sb->s_cop->max_namelen(inode); |
| 39 | if (iname->len <= 0 || iname->len > lim) |
| 40 | return -EIO; |
| 41 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 42 | /* |
| 43 | * Copy the filename to the output buffer for encrypting in-place and |
| 44 | * pad it with the needed number of NUL bytes. |
| 45 | */ |
| 46 | cryptlen = max_t(unsigned int, iname->len, FS_CRYPTO_BLOCK_SIZE); |
| 47 | cryptlen = round_up(cryptlen, padding); |
| 48 | cryptlen = min(cryptlen, lim); |
| 49 | memcpy(oname->name, iname->name, iname->len); |
| 50 | memset(oname->name + iname->len, 0, cryptlen - iname->len); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 51 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 52 | /* Initialize the IV */ |
| 53 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 54 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 55 | /* Set up the encryption request */ |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 56 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 57 | if (!req) { |
| 58 | printk_ratelimited(KERN_ERR |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 59 | "%s: skcipher_request_alloc() failed\n", __func__); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 60 | return -ENOMEM; |
| 61 | } |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 62 | skcipher_request_set_callback(req, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 63 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 64 | crypto_req_done, &wait); |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 65 | sg_init_one(&sg, oname->name, cryptlen); |
| 66 | skcipher_request_set_crypt(req, &sg, &sg, cryptlen, iv); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 67 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 68 | /* Do the encryption */ |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 69 | res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 70 | skcipher_request_free(req); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 71 | if (res < 0) { |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 72 | printk_ratelimited(KERN_ERR |
| 73 | "%s: Error (error code %d)\n", __func__, res); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 74 | return res; |
| 75 | } |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 76 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 77 | oname->len = cryptlen; |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 78 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 79 | } |
| 80 | |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 81 | /** |
| 82 | * fname_decrypt() - decrypt a filename |
| 83 | * |
| 84 | * The caller must have allocated sufficient memory for the @oname string. |
| 85 | * |
| 86 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 87 | */ |
| 88 | static int fname_decrypt(struct inode *inode, |
| 89 | const struct fscrypt_str *iname, |
| 90 | struct fscrypt_str *oname) |
| 91 | { |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 92 | struct skcipher_request *req = NULL; |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 93 | DECLARE_CRYPTO_WAIT(wait); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 94 | struct scatterlist src_sg, dst_sg; |
| 95 | struct fscrypt_info *ci = inode->i_crypt_info; |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 96 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 97 | int res = 0; |
| 98 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
| 99 | unsigned lim; |
| 100 | |
| 101 | lim = inode->i_sb->s_cop->max_namelen(inode); |
| 102 | if (iname->len <= 0 || iname->len > lim) |
| 103 | return -EIO; |
| 104 | |
| 105 | /* Allocate request */ |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 106 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 107 | if (!req) { |
| 108 | printk_ratelimited(KERN_ERR |
| 109 | "%s: crypto_request_alloc() failed\n", __func__); |
| 110 | return -ENOMEM; |
| 111 | } |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 112 | skcipher_request_set_callback(req, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 113 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 114 | crypto_req_done, &wait); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 115 | |
| 116 | /* Initialize IV */ |
| 117 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
| 118 | |
| 119 | /* Create decryption request */ |
| 120 | sg_init_one(&src_sg, iname->name, iname->len); |
| 121 | sg_init_one(&dst_sg, oname->name, oname->len); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 122 | skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 123 | res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 124 | skcipher_request_free(req); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 125 | if (res < 0) { |
| 126 | printk_ratelimited(KERN_ERR |
| 127 | "%s: Error (error code %d)\n", __func__, res); |
| 128 | return res; |
| 129 | } |
| 130 | |
| 131 | oname->len = strnlen(oname->name, iname->len); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 132 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 133 | } |
| 134 | |
| 135 | static const char *lookup_table = |
| 136 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; |
| 137 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 138 | #define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) |
| 139 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 140 | /** |
| 141 | * digest_encode() - |
| 142 | * |
| 143 | * Encodes the input digest using characters from the set [a-zA-Z0-9_+]. |
| 144 | * The encoded string is roughly 4/3 times the size of the input string. |
| 145 | */ |
| 146 | static int digest_encode(const char *src, int len, char *dst) |
| 147 | { |
| 148 | int i = 0, bits = 0, ac = 0; |
| 149 | char *cp = dst; |
| 150 | |
| 151 | while (i < len) { |
| 152 | ac += (((unsigned char) src[i]) << bits); |
| 153 | bits += 8; |
| 154 | do { |
| 155 | *cp++ = lookup_table[ac & 0x3f]; |
| 156 | ac >>= 6; |
| 157 | bits -= 6; |
| 158 | } while (bits >= 6); |
| 159 | i++; |
| 160 | } |
| 161 | if (bits) |
| 162 | *cp++ = lookup_table[ac & 0x3f]; |
| 163 | return cp - dst; |
| 164 | } |
| 165 | |
| 166 | static int digest_decode(const char *src, int len, char *dst) |
| 167 | { |
| 168 | int i = 0, bits = 0, ac = 0; |
| 169 | const char *p; |
| 170 | char *cp = dst; |
| 171 | |
| 172 | while (i < len) { |
| 173 | p = strchr(lookup_table, src[i]); |
| 174 | if (p == NULL || src[i] == 0) |
| 175 | return -2; |
| 176 | ac += (p - lookup_table) << bits; |
| 177 | bits += 6; |
| 178 | if (bits >= 8) { |
| 179 | *cp++ = ac & 0xff; |
| 180 | ac >>= 8; |
| 181 | bits -= 8; |
| 182 | } |
| 183 | i++; |
| 184 | } |
| 185 | if (ac) |
| 186 | return -1; |
| 187 | return cp - dst; |
| 188 | } |
| 189 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 190 | u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 191 | { |
| 192 | int padding = 32; |
| 193 | struct fscrypt_info *ci = inode->i_crypt_info; |
| 194 | |
| 195 | if (ci) |
| 196 | padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); |
Eric Biggers | 55be314 | 2016-09-30 01:46:18 -0400 | [diff] [blame] | 197 | ilen = max(ilen, (u32)FS_CRYPTO_BLOCK_SIZE); |
| 198 | return round_up(ilen, padding); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 199 | } |
| 200 | EXPORT_SYMBOL(fscrypt_fname_encrypted_size); |
| 201 | |
| 202 | /** |
| 203 | * fscrypt_fname_crypto_alloc_obuff() - |
| 204 | * |
| 205 | * Allocates an output buffer that is sufficient for the crypto operation |
| 206 | * specified by the context and the direction. |
| 207 | */ |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 208 | int fscrypt_fname_alloc_buffer(const struct inode *inode, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 209 | u32 ilen, struct fscrypt_str *crypto_str) |
| 210 | { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 211 | u32 olen = fscrypt_fname_encrypted_size(inode, ilen); |
| 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))); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 215 | |
| 216 | crypto_str->len = olen; |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 217 | olen = max(olen, max_encoded_len); |
| 218 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 219 | /* |
| 220 | * Allocated buffer can hold one more character to null-terminate the |
| 221 | * string |
| 222 | */ |
| 223 | crypto_str->name = kmalloc(olen + 1, GFP_NOFS); |
| 224 | if (!(crypto_str->name)) |
| 225 | return -ENOMEM; |
| 226 | return 0; |
| 227 | } |
| 228 | EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); |
| 229 | |
| 230 | /** |
| 231 | * fscrypt_fname_crypto_free_buffer() - |
| 232 | * |
| 233 | * Frees the buffer allocated for crypto operation. |
| 234 | */ |
| 235 | void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) |
| 236 | { |
| 237 | if (!crypto_str) |
| 238 | return; |
| 239 | kfree(crypto_str->name); |
| 240 | crypto_str->name = NULL; |
| 241 | } |
| 242 | EXPORT_SYMBOL(fscrypt_fname_free_buffer); |
| 243 | |
| 244 | /** |
| 245 | * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user |
| 246 | * space |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 247 | * |
| 248 | * The caller must have allocated sufficient memory for the @oname string. |
| 249 | * |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 250 | * If the key is available, we'll decrypt the disk name; otherwise, we'll encode |
| 251 | * it for presentation. Short names are directly base64-encoded, while long |
| 252 | * names are encoded in fscrypt_digested_name format. |
| 253 | * |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 254 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 255 | */ |
| 256 | int fscrypt_fname_disk_to_usr(struct inode *inode, |
| 257 | u32 hash, u32 minor_hash, |
| 258 | const struct fscrypt_str *iname, |
| 259 | struct fscrypt_str *oname) |
| 260 | { |
| 261 | const struct qstr qname = FSTR_TO_QSTR(iname); |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 262 | struct fscrypt_digested_name digested_name; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 263 | |
| 264 | if (fscrypt_is_dot_dotdot(&qname)) { |
| 265 | oname->name[0] = '.'; |
| 266 | oname->name[iname->len - 1] = '.'; |
| 267 | oname->len = iname->len; |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 268 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 269 | } |
| 270 | |
| 271 | if (iname->len < FS_CRYPTO_BLOCK_SIZE) |
| 272 | return -EUCLEAN; |
| 273 | |
| 274 | if (inode->i_crypt_info) |
| 275 | return fname_decrypt(inode, iname, oname); |
| 276 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 277 | if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 278 | oname->len = digest_encode(iname->name, iname->len, |
| 279 | oname->name); |
| 280 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 281 | } |
| 282 | if (hash) { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 283 | digested_name.hash = hash; |
| 284 | digested_name.minor_hash = minor_hash; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 285 | } else { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 286 | digested_name.hash = 0; |
| 287 | digested_name.minor_hash = 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 288 | } |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 289 | memcpy(digested_name.digest, |
| 290 | FSCRYPT_FNAME_DIGEST(iname->name, iname->len), |
| 291 | FSCRYPT_FNAME_DIGEST_SIZE); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 292 | oname->name[0] = '_'; |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 293 | oname->len = 1 + digest_encode((const char *)&digested_name, |
| 294 | sizeof(digested_name), oname->name + 1); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 295 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 296 | } |
| 297 | EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); |
| 298 | |
| 299 | /** |
| 300 | * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk |
| 301 | * space |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 302 | * |
| 303 | * The caller must have allocated sufficient memory for the @oname string. |
| 304 | * |
| 305 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 306 | */ |
| 307 | int fscrypt_fname_usr_to_disk(struct inode *inode, |
| 308 | const struct qstr *iname, |
| 309 | struct fscrypt_str *oname) |
| 310 | { |
| 311 | if (fscrypt_is_dot_dotdot(iname)) { |
| 312 | oname->name[0] = '.'; |
| 313 | oname->name[iname->len - 1] = '.'; |
| 314 | oname->len = iname->len; |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 315 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 316 | } |
| 317 | if (inode->i_crypt_info) |
| 318 | return fname_encrypt(inode, iname, oname); |
| 319 | /* |
| 320 | * Without a proper key, a user is not allowed to modify the filenames |
| 321 | * in a directory. Consequently, a user space name cannot be mapped to |
| 322 | * a disk-space name |
| 323 | */ |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 324 | return -ENOKEY; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 325 | } |
| 326 | EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); |
| 327 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 328 | /** |
| 329 | * fscrypt_setup_filename() - prepare to search a possibly encrypted directory |
| 330 | * @dir: the directory that will be searched |
| 331 | * @iname: the user-provided filename being searched for |
| 332 | * @lookup: 1 if we're allowed to proceed without the key because it's |
| 333 | * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot |
| 334 | * proceed without the key because we're going to create the dir_entry. |
| 335 | * @fname: the filename information to be filled in |
| 336 | * |
| 337 | * Given a user-provided filename @iname, this function sets @fname->disk_name |
| 338 | * to the name that would be stored in the on-disk directory entry, if possible. |
| 339 | * If the directory is unencrypted this is simply @iname. Else, if we have the |
| 340 | * directory's encryption key, then @iname is the plaintext, so we encrypt it to |
| 341 | * get the disk_name. |
| 342 | * |
| 343 | * Else, for keyless @lookup operations, @iname is the presented ciphertext, so |
| 344 | * we decode it to get either the ciphertext disk_name (for short names) or the |
| 345 | * fscrypt_digested_name (for long names). Non-@lookup operations will be |
| 346 | * impossible in this case, so we fail them with ENOKEY. |
| 347 | * |
| 348 | * If successful, fscrypt_free_filename() must be called later to clean up. |
| 349 | * |
| 350 | * Return: 0 on success, -errno on failure |
| 351 | */ |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 352 | int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, |
| 353 | int lookup, struct fscrypt_name *fname) |
| 354 | { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 355 | int ret; |
| 356 | int digested; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 357 | |
| 358 | memset(fname, 0, sizeof(struct fscrypt_name)); |
| 359 | fname->usr_fname = iname; |
| 360 | |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 361 | if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) { |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 362 | fname->disk_name.name = (unsigned char *)iname->name; |
| 363 | fname->disk_name.len = iname->len; |
| 364 | return 0; |
| 365 | } |
Eric Biggers | 2984e52 | 2017-02-21 15:07:11 -0800 | [diff] [blame] | 366 | ret = fscrypt_get_encryption_info(dir); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 367 | if (ret && ret != -EOPNOTSUPP) |
| 368 | return ret; |
| 369 | |
| 370 | if (dir->i_crypt_info) { |
| 371 | ret = fscrypt_fname_alloc_buffer(dir, iname->len, |
| 372 | &fname->crypto_buf); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 373 | if (ret) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 374 | return ret; |
| 375 | ret = fname_encrypt(dir, iname, &fname->crypto_buf); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 376 | if (ret) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 377 | goto errout; |
| 378 | fname->disk_name.name = fname->crypto_buf.name; |
| 379 | fname->disk_name.len = fname->crypto_buf.len; |
| 380 | return 0; |
| 381 | } |
| 382 | if (!lookup) |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 383 | return -ENOKEY; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 384 | |
| 385 | /* |
| 386 | * We don't have the key and we are doing a lookup; decode the |
| 387 | * user-supplied name |
| 388 | */ |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 389 | if (iname->name[0] == '_') { |
| 390 | if (iname->len != |
| 391 | 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))) |
| 392 | return -ENOENT; |
| 393 | digested = 1; |
| 394 | } else { |
| 395 | if (iname->len > |
| 396 | BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)) |
| 397 | return -ENOENT; |
| 398 | digested = 0; |
| 399 | } |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 400 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 401 | fname->crypto_buf.name = |
| 402 | kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE, |
| 403 | sizeof(struct fscrypt_digested_name)), |
| 404 | GFP_KERNEL); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 405 | if (fname->crypto_buf.name == NULL) |
| 406 | return -ENOMEM; |
| 407 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 408 | ret = digest_decode(iname->name + digested, iname->len - digested, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 409 | fname->crypto_buf.name); |
| 410 | if (ret < 0) { |
| 411 | ret = -ENOENT; |
| 412 | goto errout; |
| 413 | } |
| 414 | fname->crypto_buf.len = ret; |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 415 | if (digested) { |
| 416 | const struct fscrypt_digested_name *n = |
| 417 | (const void *)fname->crypto_buf.name; |
| 418 | fname->hash = n->hash; |
| 419 | fname->minor_hash = n->minor_hash; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 420 | } else { |
| 421 | fname->disk_name.name = fname->crypto_buf.name; |
| 422 | fname->disk_name.len = fname->crypto_buf.len; |
| 423 | } |
| 424 | return 0; |
| 425 | |
| 426 | errout: |
| 427 | fscrypt_fname_free_buffer(&fname->crypto_buf); |
| 428 | return ret; |
| 429 | } |
| 430 | EXPORT_SYMBOL(fscrypt_setup_filename); |