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> |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 15 | #include <crypto/skcipher.h> |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 16 | #include "fscrypt_private.h" |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 17 | |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 18 | static 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 | } |
| 28 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 29 | /** |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 30 | * fname_encrypt() - encrypt a filename |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 31 | * |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 32 | * The output buffer must be at least as large as the input buffer. |
| 33 | * Any extra space is filled with NUL padding before encryption. |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 34 | * |
| 35 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 36 | */ |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 37 | int fname_encrypt(struct inode *inode, const struct qstr *iname, |
| 38 | u8 *out, unsigned int olen) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 39 | { |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 40 | struct skcipher_request *req = NULL; |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 41 | DECLARE_CRYPTO_WAIT(wait); |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 42 | struct crypto_skcipher *tfm = inode->i_crypt_info->ci_ctfm; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 43 | int res = 0; |
| 44 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 45 | struct scatterlist sg; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 46 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 47 | /* |
| 48 | * Copy the filename to the output buffer for encrypting in-place and |
| 49 | * pad it with the needed number of NUL bytes. |
| 50 | */ |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 51 | if (WARN_ON(olen < iname->len)) |
| 52 | return -ENOBUFS; |
| 53 | memcpy(out, iname->name, iname->len); |
| 54 | memset(out + iname->len, 0, olen - iname->len); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 55 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 56 | /* Initialize the IV */ |
| 57 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 58 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 59 | /* Set up the encryption request */ |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 60 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 61 | if (!req) { |
| 62 | printk_ratelimited(KERN_ERR |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 63 | "%s: skcipher_request_alloc() failed\n", __func__); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 64 | return -ENOMEM; |
| 65 | } |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 66 | skcipher_request_set_callback(req, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 67 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 68 | crypto_req_done, &wait); |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 69 | sg_init_one(&sg, out, olen); |
| 70 | skcipher_request_set_crypt(req, &sg, &sg, olen, iv); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 71 | |
Eric Biggers | 3c7018e | 2016-11-13 20:35:52 -0500 | [diff] [blame] | 72 | /* Do the encryption */ |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 73 | res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 74 | skcipher_request_free(req); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 75 | if (res < 0) { |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 76 | printk_ratelimited(KERN_ERR |
| 77 | "%s: Error (error code %d)\n", __func__, res); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 78 | return res; |
| 79 | } |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 80 | |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 81 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 82 | } |
| 83 | |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 84 | /** |
| 85 | * fname_decrypt() - decrypt a filename |
| 86 | * |
| 87 | * The caller must have allocated sufficient memory for the @oname string. |
| 88 | * |
| 89 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 90 | */ |
| 91 | static int fname_decrypt(struct inode *inode, |
| 92 | const struct fscrypt_str *iname, |
| 93 | struct fscrypt_str *oname) |
| 94 | { |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 95 | struct skcipher_request *req = NULL; |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 96 | DECLARE_CRYPTO_WAIT(wait); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 97 | struct scatterlist src_sg, dst_sg; |
| 98 | struct fscrypt_info *ci = inode->i_crypt_info; |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 99 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 100 | int res = 0; |
| 101 | char iv[FS_CRYPTO_BLOCK_SIZE]; |
| 102 | unsigned lim; |
| 103 | |
| 104 | lim = inode->i_sb->s_cop->max_namelen(inode); |
| 105 | if (iname->len <= 0 || iname->len > lim) |
| 106 | return -EIO; |
| 107 | |
| 108 | /* Allocate request */ |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 109 | req = skcipher_request_alloc(tfm, GFP_NOFS); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 110 | if (!req) { |
| 111 | printk_ratelimited(KERN_ERR |
| 112 | "%s: crypto_request_alloc() failed\n", __func__); |
| 113 | return -ENOMEM; |
| 114 | } |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 115 | skcipher_request_set_callback(req, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 116 | CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 117 | crypto_req_done, &wait); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 118 | |
| 119 | /* Initialize IV */ |
| 120 | memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); |
| 121 | |
| 122 | /* Create decryption request */ |
| 123 | sg_init_one(&src_sg, iname->name, iname->len); |
| 124 | sg_init_one(&dst_sg, oname->name, oname->len); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 125 | skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 126 | res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait); |
Linus Torvalds | d407574 | 2016-03-21 11:03:02 -0700 | [diff] [blame] | 127 | skcipher_request_free(req); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 128 | if (res < 0) { |
| 129 | printk_ratelimited(KERN_ERR |
| 130 | "%s: Error (error code %d)\n", __func__, res); |
| 131 | return res; |
| 132 | } |
| 133 | |
| 134 | oname->len = strnlen(oname->name, iname->len); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 135 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 136 | } |
| 137 | |
| 138 | static const char *lookup_table = |
| 139 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; |
| 140 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 141 | #define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) |
| 142 | |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 143 | /** |
| 144 | * digest_encode() - |
| 145 | * |
| 146 | * Encodes the input digest using characters from the set [a-zA-Z0-9_+]. |
| 147 | * The encoded string is roughly 4/3 times the size of the input string. |
| 148 | */ |
| 149 | static int digest_encode(const char *src, int len, char *dst) |
| 150 | { |
| 151 | int i = 0, bits = 0, ac = 0; |
| 152 | char *cp = dst; |
| 153 | |
| 154 | while (i < len) { |
| 155 | ac += (((unsigned char) src[i]) << bits); |
| 156 | bits += 8; |
| 157 | do { |
| 158 | *cp++ = lookup_table[ac & 0x3f]; |
| 159 | ac >>= 6; |
| 160 | bits -= 6; |
| 161 | } while (bits >= 6); |
| 162 | i++; |
| 163 | } |
| 164 | if (bits) |
| 165 | *cp++ = lookup_table[ac & 0x3f]; |
| 166 | return cp - dst; |
| 167 | } |
| 168 | |
| 169 | static int digest_decode(const char *src, int len, char *dst) |
| 170 | { |
| 171 | int i = 0, bits = 0, ac = 0; |
| 172 | const char *p; |
| 173 | char *cp = dst; |
| 174 | |
| 175 | while (i < len) { |
| 176 | p = strchr(lookup_table, src[i]); |
| 177 | if (p == NULL || src[i] == 0) |
| 178 | return -2; |
| 179 | ac += (p - lookup_table) << bits; |
| 180 | bits += 6; |
| 181 | if (bits >= 8) { |
| 182 | *cp++ = ac & 0xff; |
| 183 | ac >>= 8; |
| 184 | bits -= 8; |
| 185 | } |
| 186 | i++; |
| 187 | } |
| 188 | if (ac) |
| 189 | return -1; |
| 190 | return cp - dst; |
| 191 | } |
| 192 | |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 193 | bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, |
| 194 | u32 max_len, u32 *encrypted_len_ret) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 195 | { |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 196 | int padding = 4 << (inode->i_crypt_info->ci_flags & |
| 197 | FS_POLICY_FLAGS_PAD_MASK); |
| 198 | u32 encrypted_len; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 199 | |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 200 | if (orig_len > max_len) |
| 201 | return false; |
| 202 | encrypted_len = max(orig_len, (u32)FS_CRYPTO_BLOCK_SIZE); |
| 203 | encrypted_len = round_up(encrypted_len, padding); |
| 204 | *encrypted_len_ret = min(encrypted_len, max_len); |
| 205 | return true; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 206 | } |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 207 | |
| 208 | /** |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 209 | * fscrypt_fname_alloc_buffer - allocate a buffer for presented filenames |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 210 | * |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 211 | * Allocate a buffer that is large enough to hold any decrypted or encoded |
| 212 | * filename (null-terminated), for the given maximum encrypted filename length. |
| 213 | * |
| 214 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 215 | */ |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 216 | int fscrypt_fname_alloc_buffer(const struct inode *inode, |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 217 | u32 max_encrypted_len, |
| 218 | struct fscrypt_str *crypto_str) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 219 | { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 220 | const u32 max_encoded_len = |
| 221 | max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE), |
| 222 | 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))); |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 223 | u32 max_presented_len; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 224 | |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 225 | max_presented_len = max(max_encoded_len, max_encrypted_len); |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 226 | |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 227 | crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS); |
| 228 | if (!crypto_str->name) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 229 | return -ENOMEM; |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 230 | crypto_str->len = max_presented_len; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 231 | return 0; |
| 232 | } |
| 233 | EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); |
| 234 | |
| 235 | /** |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 236 | * fscrypt_fname_free_buffer - free the buffer for presented filenames |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 237 | * |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 238 | * Free the buffer allocated by fscrypt_fname_alloc_buffer(). |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 239 | */ |
| 240 | void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) |
| 241 | { |
| 242 | if (!crypto_str) |
| 243 | return; |
| 244 | kfree(crypto_str->name); |
| 245 | crypto_str->name = NULL; |
| 246 | } |
| 247 | EXPORT_SYMBOL(fscrypt_fname_free_buffer); |
| 248 | |
| 249 | /** |
| 250 | * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user |
| 251 | * space |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 252 | * |
| 253 | * The caller must have allocated sufficient memory for the @oname string. |
| 254 | * |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 255 | * If the key is available, we'll decrypt the disk name; otherwise, we'll encode |
| 256 | * it for presentation. Short names are directly base64-encoded, while long |
| 257 | * names are encoded in fscrypt_digested_name format. |
| 258 | * |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 259 | * Return: 0 on success, -errno on failure |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 260 | */ |
| 261 | int fscrypt_fname_disk_to_usr(struct inode *inode, |
| 262 | u32 hash, u32 minor_hash, |
| 263 | const struct fscrypt_str *iname, |
| 264 | struct fscrypt_str *oname) |
| 265 | { |
| 266 | const struct qstr qname = FSTR_TO_QSTR(iname); |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 267 | struct fscrypt_digested_name digested_name; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 268 | |
| 269 | if (fscrypt_is_dot_dotdot(&qname)) { |
| 270 | oname->name[0] = '.'; |
| 271 | oname->name[iname->len - 1] = '.'; |
| 272 | oname->len = iname->len; |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 273 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 274 | } |
| 275 | |
| 276 | if (iname->len < FS_CRYPTO_BLOCK_SIZE) |
| 277 | return -EUCLEAN; |
| 278 | |
| 279 | if (inode->i_crypt_info) |
| 280 | return fname_decrypt(inode, iname, oname); |
| 281 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 282 | if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 283 | oname->len = digest_encode(iname->name, iname->len, |
| 284 | oname->name); |
| 285 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 286 | } |
| 287 | if (hash) { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 288 | digested_name.hash = hash; |
| 289 | digested_name.minor_hash = minor_hash; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 290 | } else { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 291 | digested_name.hash = 0; |
| 292 | digested_name.minor_hash = 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 293 | } |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 294 | memcpy(digested_name.digest, |
| 295 | FSCRYPT_FNAME_DIGEST(iname->name, iname->len), |
| 296 | FSCRYPT_FNAME_DIGEST_SIZE); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 297 | oname->name[0] = '_'; |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 298 | oname->len = 1 + digest_encode((const char *)&digested_name, |
| 299 | sizeof(digested_name), oname->name + 1); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 300 | return 0; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 301 | } |
| 302 | EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); |
| 303 | |
| 304 | /** |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 305 | * fscrypt_setup_filename() - prepare to search a possibly encrypted directory |
| 306 | * @dir: the directory that will be searched |
| 307 | * @iname: the user-provided filename being searched for |
| 308 | * @lookup: 1 if we're allowed to proceed without the key because it's |
| 309 | * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot |
| 310 | * proceed without the key because we're going to create the dir_entry. |
| 311 | * @fname: the filename information to be filled in |
| 312 | * |
| 313 | * Given a user-provided filename @iname, this function sets @fname->disk_name |
| 314 | * to the name that would be stored in the on-disk directory entry, if possible. |
| 315 | * If the directory is unencrypted this is simply @iname. Else, if we have the |
| 316 | * directory's encryption key, then @iname is the plaintext, so we encrypt it to |
| 317 | * get the disk_name. |
| 318 | * |
| 319 | * Else, for keyless @lookup operations, @iname is the presented ciphertext, so |
| 320 | * we decode it to get either the ciphertext disk_name (for short names) or the |
| 321 | * fscrypt_digested_name (for long names). Non-@lookup operations will be |
| 322 | * impossible in this case, so we fail them with ENOKEY. |
| 323 | * |
| 324 | * If successful, fscrypt_free_filename() must be called later to clean up. |
| 325 | * |
| 326 | * Return: 0 on success, -errno on failure |
| 327 | */ |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 328 | int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, |
| 329 | int lookup, struct fscrypt_name *fname) |
| 330 | { |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 331 | int ret; |
| 332 | int digested; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 333 | |
| 334 | memset(fname, 0, sizeof(struct fscrypt_name)); |
| 335 | fname->usr_fname = iname; |
| 336 | |
Jaegeuk Kim | 8dec074 | 2017-06-22 12:14:40 -0700 | [diff] [blame] | 337 | if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) { |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 338 | fname->disk_name.name = (unsigned char *)iname->name; |
| 339 | fname->disk_name.len = iname->len; |
| 340 | return 0; |
| 341 | } |
Eric Biggers | 2984e52 | 2017-02-21 15:07:11 -0800 | [diff] [blame] | 342 | ret = fscrypt_get_encryption_info(dir); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 343 | if (ret && ret != -EOPNOTSUPP) |
| 344 | return ret; |
| 345 | |
| 346 | if (dir->i_crypt_info) { |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 347 | if (!fscrypt_fname_encrypted_size(dir, iname->len, |
| 348 | dir->i_sb->s_cop->max_namelen(dir), |
| 349 | &fname->crypto_buf.len)) |
| 350 | return -ENAMETOOLONG; |
| 351 | fname->crypto_buf.name = kmalloc(fname->crypto_buf.len, |
| 352 | GFP_NOFS); |
| 353 | if (!fname->crypto_buf.name) |
| 354 | return -ENOMEM; |
| 355 | |
| 356 | ret = fname_encrypt(dir, iname, fname->crypto_buf.name, |
| 357 | fname->crypto_buf.len); |
Eric Biggers | ef1eb3a | 2016-09-15 17:25:55 -0400 | [diff] [blame] | 358 | if (ret) |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 359 | goto errout; |
| 360 | fname->disk_name.name = fname->crypto_buf.name; |
| 361 | fname->disk_name.len = fname->crypto_buf.len; |
| 362 | return 0; |
| 363 | } |
| 364 | if (!lookup) |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 365 | return -ENOKEY; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 366 | |
| 367 | /* |
| 368 | * We don't have the key and we are doing a lookup; decode the |
| 369 | * user-supplied name |
| 370 | */ |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 371 | if (iname->name[0] == '_') { |
| 372 | if (iname->len != |
| 373 | 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))) |
| 374 | return -ENOENT; |
| 375 | digested = 1; |
| 376 | } else { |
| 377 | if (iname->len > |
| 378 | BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)) |
| 379 | return -ENOENT; |
| 380 | digested = 0; |
| 381 | } |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 382 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 383 | fname->crypto_buf.name = |
| 384 | kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE, |
| 385 | sizeof(struct fscrypt_digested_name)), |
| 386 | GFP_KERNEL); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 387 | if (fname->crypto_buf.name == NULL) |
| 388 | return -ENOMEM; |
| 389 | |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 390 | ret = digest_decode(iname->name + digested, iname->len - digested, |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 391 | fname->crypto_buf.name); |
| 392 | if (ret < 0) { |
| 393 | ret = -ENOENT; |
| 394 | goto errout; |
| 395 | } |
| 396 | fname->crypto_buf.len = ret; |
Hyojun Kim | 63da420 | 2017-10-06 17:10:08 -0700 | [diff] [blame] | 397 | if (digested) { |
| 398 | const struct fscrypt_digested_name *n = |
| 399 | (const void *)fname->crypto_buf.name; |
| 400 | fname->hash = n->hash; |
| 401 | fname->minor_hash = n->minor_hash; |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 402 | } else { |
| 403 | fname->disk_name.name = fname->crypto_buf.name; |
| 404 | fname->disk_name.len = fname->crypto_buf.len; |
| 405 | } |
| 406 | return 0; |
| 407 | |
| 408 | errout: |
Jaegeuk Kim | d919765 | 2018-01-05 10:44:52 -0800 | [diff] [blame] | 409 | kfree(fname->crypto_buf.name); |
Jaegeuk Kim | 0b81d07 | 2015-05-15 16:26:10 -0700 | [diff] [blame] | 410 | return ret; |
| 411 | } |
| 412 | EXPORT_SYMBOL(fscrypt_setup_filename); |