149525e5eSSascha Hauer // SPDX-License-Identifier: GPL-2.0 249525e5eSSascha Hauer /* 349525e5eSSascha Hauer * This file is part of UBIFS. 449525e5eSSascha Hauer * 549525e5eSSascha Hauer * Copyright (C) 2018 Pengutronix, Sascha Hauer <s.hauer@pengutronix.de> 649525e5eSSascha Hauer */ 749525e5eSSascha Hauer 849525e5eSSascha Hauer /* 949525e5eSSascha Hauer * This file implements various helper functions for UBIFS authentication support 1049525e5eSSascha Hauer */ 1149525e5eSSascha Hauer 1249525e5eSSascha Hauer #include <linux/crypto.h> 13817aa094SSascha Hauer #include <linux/verification.h> 1449525e5eSSascha Hauer #include <crypto/hash.h> 1549525e5eSSascha Hauer #include <crypto/sha.h> 1649525e5eSSascha Hauer #include <crypto/algapi.h> 1749525e5eSSascha Hauer #include <keys/user-type.h> 18817aa094SSascha Hauer #include <keys/asymmetric-type.h> 1949525e5eSSascha Hauer 2049525e5eSSascha Hauer #include "ubifs.h" 2149525e5eSSascha Hauer 2249525e5eSSascha Hauer /** 2349525e5eSSascha Hauer * ubifs_node_calc_hash - calculate the hash of a UBIFS node 2449525e5eSSascha Hauer * @c: UBIFS file-system description object 2549525e5eSSascha Hauer * @node: the node to calculate a hash for 2649525e5eSSascha Hauer * @hash: the returned hash 2749525e5eSSascha Hauer * 2849525e5eSSascha Hauer * Returns 0 for success or a negative error code otherwise. 2949525e5eSSascha Hauer */ 3049525e5eSSascha Hauer int __ubifs_node_calc_hash(const struct ubifs_info *c, const void *node, 3149525e5eSSascha Hauer u8 *hash) 3249525e5eSSascha Hauer { 3349525e5eSSascha Hauer const struct ubifs_ch *ch = node; 3449525e5eSSascha Hauer SHASH_DESC_ON_STACK(shash, c->hash_tfm); 3549525e5eSSascha Hauer int err; 3649525e5eSSascha Hauer 3749525e5eSSascha Hauer shash->tfm = c->hash_tfm; 3849525e5eSSascha Hauer 3949525e5eSSascha Hauer err = crypto_shash_digest(shash, node, le32_to_cpu(ch->len), hash); 4049525e5eSSascha Hauer if (err < 0) 4149525e5eSSascha Hauer return err; 4249525e5eSSascha Hauer return 0; 4349525e5eSSascha Hauer } 4449525e5eSSascha Hauer 4549525e5eSSascha Hauer /** 4649525e5eSSascha Hauer * ubifs_hash_calc_hmac - calculate a HMAC from a hash 4749525e5eSSascha Hauer * @c: UBIFS file-system description object 4849525e5eSSascha Hauer * @hash: the node to calculate a HMAC for 4949525e5eSSascha Hauer * @hmac: the returned HMAC 5049525e5eSSascha Hauer * 5149525e5eSSascha Hauer * Returns 0 for success or a negative error code otherwise. 5249525e5eSSascha Hauer */ 5349525e5eSSascha Hauer static int ubifs_hash_calc_hmac(const struct ubifs_info *c, const u8 *hash, 5449525e5eSSascha Hauer u8 *hmac) 5549525e5eSSascha Hauer { 5649525e5eSSascha Hauer SHASH_DESC_ON_STACK(shash, c->hmac_tfm); 5749525e5eSSascha Hauer int err; 5849525e5eSSascha Hauer 5949525e5eSSascha Hauer shash->tfm = c->hmac_tfm; 6049525e5eSSascha Hauer 6149525e5eSSascha Hauer err = crypto_shash_digest(shash, hash, c->hash_len, hmac); 6249525e5eSSascha Hauer if (err < 0) 6349525e5eSSascha Hauer return err; 6449525e5eSSascha Hauer return 0; 6549525e5eSSascha Hauer } 6649525e5eSSascha Hauer 6749525e5eSSascha Hauer /** 6849525e5eSSascha Hauer * ubifs_prepare_auth_node - Prepare an authentication node 6949525e5eSSascha Hauer * @c: UBIFS file-system description object 7049525e5eSSascha Hauer * @node: the node to calculate a hash for 7149525e5eSSascha Hauer * @hash: input hash of previous nodes 7249525e5eSSascha Hauer * 7349525e5eSSascha Hauer * This function prepares an authentication node for writing onto flash. 7449525e5eSSascha Hauer * It creates a HMAC from the given input hash and writes it to the node. 7549525e5eSSascha Hauer * 7649525e5eSSascha Hauer * Returns 0 for success or a negative error code otherwise. 7749525e5eSSascha Hauer */ 7849525e5eSSascha Hauer int ubifs_prepare_auth_node(struct ubifs_info *c, void *node, 7949525e5eSSascha Hauer struct shash_desc *inhash) 8049525e5eSSascha Hauer { 8149525e5eSSascha Hauer struct ubifs_auth_node *auth = node; 8249525e5eSSascha Hauer u8 *hash; 8349525e5eSSascha Hauer int err; 8449525e5eSSascha Hauer 8549525e5eSSascha Hauer hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS); 8649525e5eSSascha Hauer if (!hash) 8749525e5eSSascha Hauer return -ENOMEM; 8849525e5eSSascha Hauer 89f4844b35SArnd Bergmann { 90f4844b35SArnd Bergmann SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm); 91f4844b35SArnd Bergmann 9249525e5eSSascha Hauer hash_desc->tfm = c->hash_tfm; 9349525e5eSSascha Hauer ubifs_shash_copy_state(c, inhash, hash_desc); 9449525e5eSSascha Hauer 9549525e5eSSascha Hauer err = crypto_shash_final(hash_desc, hash); 9649525e5eSSascha Hauer if (err) 9749525e5eSSascha Hauer goto out; 98f4844b35SArnd Bergmann } 9949525e5eSSascha Hauer 10049525e5eSSascha Hauer err = ubifs_hash_calc_hmac(c, hash, auth->hmac); 10149525e5eSSascha Hauer if (err) 10249525e5eSSascha Hauer goto out; 10349525e5eSSascha Hauer 10449525e5eSSascha Hauer auth->ch.node_type = UBIFS_AUTH_NODE; 10549525e5eSSascha Hauer ubifs_prepare_node(c, auth, ubifs_auth_node_sz(c), 0); 10649525e5eSSascha Hauer 10749525e5eSSascha Hauer err = 0; 10849525e5eSSascha Hauer out: 10949525e5eSSascha Hauer kfree(hash); 11049525e5eSSascha Hauer 11149525e5eSSascha Hauer return err; 11249525e5eSSascha Hauer } 11349525e5eSSascha Hauer 11449525e5eSSascha Hauer static struct shash_desc *ubifs_get_desc(const struct ubifs_info *c, 11549525e5eSSascha Hauer struct crypto_shash *tfm) 11649525e5eSSascha Hauer { 11749525e5eSSascha Hauer struct shash_desc *desc; 11849525e5eSSascha Hauer int err; 11949525e5eSSascha Hauer 12049525e5eSSascha Hauer if (!ubifs_authenticated(c)) 12149525e5eSSascha Hauer return NULL; 12249525e5eSSascha Hauer 12349525e5eSSascha Hauer desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL); 12449525e5eSSascha Hauer if (!desc) 12549525e5eSSascha Hauer return ERR_PTR(-ENOMEM); 12649525e5eSSascha Hauer 12749525e5eSSascha Hauer desc->tfm = tfm; 12849525e5eSSascha Hauer 12949525e5eSSascha Hauer err = crypto_shash_init(desc); 13049525e5eSSascha Hauer if (err) { 13149525e5eSSascha Hauer kfree(desc); 13249525e5eSSascha Hauer return ERR_PTR(err); 13349525e5eSSascha Hauer } 13449525e5eSSascha Hauer 13549525e5eSSascha Hauer return desc; 13649525e5eSSascha Hauer } 13749525e5eSSascha Hauer 13849525e5eSSascha Hauer /** 13949525e5eSSascha Hauer * __ubifs_hash_get_desc - get a descriptor suitable for hashing a node 14049525e5eSSascha Hauer * @c: UBIFS file-system description object 14149525e5eSSascha Hauer * 14249525e5eSSascha Hauer * This function returns a descriptor suitable for hashing a node. Free after use 14349525e5eSSascha Hauer * with kfree. 14449525e5eSSascha Hauer */ 14549525e5eSSascha Hauer struct shash_desc *__ubifs_hash_get_desc(const struct ubifs_info *c) 14649525e5eSSascha Hauer { 14749525e5eSSascha Hauer return ubifs_get_desc(c, c->hash_tfm); 14849525e5eSSascha Hauer } 14949525e5eSSascha Hauer 15049525e5eSSascha Hauer /** 15149525e5eSSascha Hauer * ubifs_bad_hash - Report hash mismatches 15249525e5eSSascha Hauer * @c: UBIFS file-system description object 15349525e5eSSascha Hauer * @node: the node 15449525e5eSSascha Hauer * @hash: the expected hash 15549525e5eSSascha Hauer * @lnum: the LEB @node was read from 15649525e5eSSascha Hauer * @offs: offset in LEB @node was read from 15749525e5eSSascha Hauer * 15849525e5eSSascha Hauer * This function reports a hash mismatch when a node has a different hash than 15949525e5eSSascha Hauer * expected. 16049525e5eSSascha Hauer */ 16149525e5eSSascha Hauer void ubifs_bad_hash(const struct ubifs_info *c, const void *node, const u8 *hash, 16249525e5eSSascha Hauer int lnum, int offs) 16349525e5eSSascha Hauer { 16449525e5eSSascha Hauer int len = min(c->hash_len, 20); 16549525e5eSSascha Hauer int cropped = len != c->hash_len; 16649525e5eSSascha Hauer const char *cont = cropped ? "..." : ""; 16749525e5eSSascha Hauer 16849525e5eSSascha Hauer u8 calc[UBIFS_HASH_ARR_SZ]; 16949525e5eSSascha Hauer 17049525e5eSSascha Hauer __ubifs_node_calc_hash(c, node, calc); 17149525e5eSSascha Hauer 17249525e5eSSascha Hauer ubifs_err(c, "hash mismatch on node at LEB %d:%d", lnum, offs); 17349525e5eSSascha Hauer ubifs_err(c, "hash expected: %*ph%s", len, hash, cont); 17449525e5eSSascha Hauer ubifs_err(c, "hash calculated: %*ph%s", len, calc, cont); 17549525e5eSSascha Hauer } 17649525e5eSSascha Hauer 17749525e5eSSascha Hauer /** 17849525e5eSSascha Hauer * __ubifs_node_check_hash - check the hash of a node against given hash 17949525e5eSSascha Hauer * @c: UBIFS file-system description object 18049525e5eSSascha Hauer * @node: the node 18149525e5eSSascha Hauer * @expected: the expected hash 18249525e5eSSascha Hauer * 18349525e5eSSascha Hauer * This function calculates a hash over a node and compares it to the given hash. 18449525e5eSSascha Hauer * Returns 0 if both hashes are equal or authentication is disabled, otherwise a 18549525e5eSSascha Hauer * negative error code is returned. 18649525e5eSSascha Hauer */ 18749525e5eSSascha Hauer int __ubifs_node_check_hash(const struct ubifs_info *c, const void *node, 18849525e5eSSascha Hauer const u8 *expected) 18949525e5eSSascha Hauer { 19049525e5eSSascha Hauer u8 calc[UBIFS_HASH_ARR_SZ]; 19149525e5eSSascha Hauer int err; 19249525e5eSSascha Hauer 19349525e5eSSascha Hauer err = __ubifs_node_calc_hash(c, node, calc); 19449525e5eSSascha Hauer if (err) 19549525e5eSSascha Hauer return err; 19649525e5eSSascha Hauer 19749525e5eSSascha Hauer if (ubifs_check_hash(c, expected, calc)) 19849525e5eSSascha Hauer return -EPERM; 19949525e5eSSascha Hauer 20049525e5eSSascha Hauer return 0; 20149525e5eSSascha Hauer } 20249525e5eSSascha Hauer 20349525e5eSSascha Hauer /** 204817aa094SSascha Hauer * ubifs_sb_verify_signature - verify the signature of a superblock 205817aa094SSascha Hauer * @c: UBIFS file-system description object 206817aa094SSascha Hauer * @sup: The superblock node 207817aa094SSascha Hauer * 208817aa094SSascha Hauer * To support offline signed images the superblock can be signed with a 209817aa094SSascha Hauer * PKCS#7 signature. The signature is placed directly behind the superblock 210817aa094SSascha Hauer * node in an ubifs_sig_node. 211817aa094SSascha Hauer * 212817aa094SSascha Hauer * Returns 0 when the signature can be successfully verified or a negative 213817aa094SSascha Hauer * error code if not. 214817aa094SSascha Hauer */ 215817aa094SSascha Hauer int ubifs_sb_verify_signature(struct ubifs_info *c, 216817aa094SSascha Hauer const struct ubifs_sb_node *sup) 217817aa094SSascha Hauer { 218817aa094SSascha Hauer int err; 219817aa094SSascha Hauer struct ubifs_scan_leb *sleb; 220817aa094SSascha Hauer struct ubifs_scan_node *snod; 221817aa094SSascha Hauer const struct ubifs_sig_node *signode; 222817aa094SSascha Hauer 223817aa094SSascha Hauer sleb = ubifs_scan(c, UBIFS_SB_LNUM, UBIFS_SB_NODE_SZ, c->sbuf, 0); 224817aa094SSascha Hauer if (IS_ERR(sleb)) { 225817aa094SSascha Hauer err = PTR_ERR(sleb); 226817aa094SSascha Hauer return err; 227817aa094SSascha Hauer } 228817aa094SSascha Hauer 229817aa094SSascha Hauer if (sleb->nodes_cnt == 0) { 230817aa094SSascha Hauer ubifs_err(c, "Unable to find signature node"); 231817aa094SSascha Hauer err = -EINVAL; 232817aa094SSascha Hauer goto out_destroy; 233817aa094SSascha Hauer } 234817aa094SSascha Hauer 235817aa094SSascha Hauer snod = list_first_entry(&sleb->nodes, struct ubifs_scan_node, list); 236817aa094SSascha Hauer 237817aa094SSascha Hauer if (snod->type != UBIFS_SIG_NODE) { 238817aa094SSascha Hauer ubifs_err(c, "Signature node is of wrong type"); 239817aa094SSascha Hauer err = -EINVAL; 240817aa094SSascha Hauer goto out_destroy; 241817aa094SSascha Hauer } 242817aa094SSascha Hauer 243817aa094SSascha Hauer signode = snod->node; 244817aa094SSascha Hauer 245817aa094SSascha Hauer if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) { 246817aa094SSascha Hauer ubifs_err(c, "invalid signature len %d", le32_to_cpu(signode->len)); 247817aa094SSascha Hauer err = -EINVAL; 248817aa094SSascha Hauer goto out_destroy; 249817aa094SSascha Hauer } 250817aa094SSascha Hauer 251817aa094SSascha Hauer if (le32_to_cpu(signode->type) != UBIFS_SIGNATURE_TYPE_PKCS7) { 252817aa094SSascha Hauer ubifs_err(c, "Signature type %d is not supported\n", 253817aa094SSascha Hauer le32_to_cpu(signode->type)); 254817aa094SSascha Hauer err = -EINVAL; 255817aa094SSascha Hauer goto out_destroy; 256817aa094SSascha Hauer } 257817aa094SSascha Hauer 258817aa094SSascha Hauer err = verify_pkcs7_signature(sup, sizeof(struct ubifs_sb_node), 259817aa094SSascha Hauer signode->sig, le32_to_cpu(signode->len), 260817aa094SSascha Hauer NULL, VERIFYING_UNSPECIFIED_SIGNATURE, 261817aa094SSascha Hauer NULL, NULL); 262817aa094SSascha Hauer 263817aa094SSascha Hauer if (err) 264817aa094SSascha Hauer ubifs_err(c, "Failed to verify signature"); 265817aa094SSascha Hauer else 266817aa094SSascha Hauer ubifs_msg(c, "Successfully verified super block signature"); 267817aa094SSascha Hauer 268817aa094SSascha Hauer out_destroy: 269817aa094SSascha Hauer ubifs_scan_destroy(sleb); 270817aa094SSascha Hauer 271817aa094SSascha Hauer return err; 272817aa094SSascha Hauer } 273817aa094SSascha Hauer 274817aa094SSascha Hauer /** 27549525e5eSSascha Hauer * ubifs_init_authentication - initialize UBIFS authentication support 27649525e5eSSascha Hauer * @c: UBIFS file-system description object 27749525e5eSSascha Hauer * 27849525e5eSSascha Hauer * This function returns 0 for success or a negative error code otherwise. 27949525e5eSSascha Hauer */ 28049525e5eSSascha Hauer int ubifs_init_authentication(struct ubifs_info *c) 28149525e5eSSascha Hauer { 28249525e5eSSascha Hauer struct key *keyring_key; 28349525e5eSSascha Hauer const struct user_key_payload *ukp; 28449525e5eSSascha Hauer int err; 28549525e5eSSascha Hauer char hmac_name[CRYPTO_MAX_ALG_NAME]; 28649525e5eSSascha Hauer 28749525e5eSSascha Hauer if (!c->auth_hash_name) { 28849525e5eSSascha Hauer ubifs_err(c, "authentication hash name needed with authentication"); 28949525e5eSSascha Hauer return -EINVAL; 29049525e5eSSascha Hauer } 29149525e5eSSascha Hauer 29249525e5eSSascha Hauer c->auth_hash_algo = match_string(hash_algo_name, HASH_ALGO__LAST, 29349525e5eSSascha Hauer c->auth_hash_name); 29449525e5eSSascha Hauer if ((int)c->auth_hash_algo < 0) { 29549525e5eSSascha Hauer ubifs_err(c, "Unknown hash algo %s specified", 29649525e5eSSascha Hauer c->auth_hash_name); 29749525e5eSSascha Hauer return -EINVAL; 29849525e5eSSascha Hauer } 29949525e5eSSascha Hauer 30049525e5eSSascha Hauer snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)", 30149525e5eSSascha Hauer c->auth_hash_name); 30249525e5eSSascha Hauer 30349525e5eSSascha Hauer keyring_key = request_key(&key_type_logon, c->auth_key_name, NULL); 30449525e5eSSascha Hauer 30549525e5eSSascha Hauer if (IS_ERR(keyring_key)) { 30649525e5eSSascha Hauer ubifs_err(c, "Failed to request key: %ld", 30749525e5eSSascha Hauer PTR_ERR(keyring_key)); 30849525e5eSSascha Hauer return PTR_ERR(keyring_key); 30949525e5eSSascha Hauer } 31049525e5eSSascha Hauer 31149525e5eSSascha Hauer down_read(&keyring_key->sem); 31249525e5eSSascha Hauer 31349525e5eSSascha Hauer if (keyring_key->type != &key_type_logon) { 31449525e5eSSascha Hauer ubifs_err(c, "key type must be logon"); 31549525e5eSSascha Hauer err = -ENOKEY; 31649525e5eSSascha Hauer goto out; 31749525e5eSSascha Hauer } 31849525e5eSSascha Hauer 31949525e5eSSascha Hauer ukp = user_key_payload_locked(keyring_key); 32049525e5eSSascha Hauer if (!ukp) { 32149525e5eSSascha Hauer /* key was revoked before we acquired its semaphore */ 32249525e5eSSascha Hauer err = -EKEYREVOKED; 32349525e5eSSascha Hauer goto out; 32449525e5eSSascha Hauer } 32549525e5eSSascha Hauer 3263d234b33SEric Biggers c->hash_tfm = crypto_alloc_shash(c->auth_hash_name, 0, 0); 32749525e5eSSascha Hauer if (IS_ERR(c->hash_tfm)) { 32849525e5eSSascha Hauer err = PTR_ERR(c->hash_tfm); 32949525e5eSSascha Hauer ubifs_err(c, "Can not allocate %s: %d", 33049525e5eSSascha Hauer c->auth_hash_name, err); 33149525e5eSSascha Hauer goto out; 33249525e5eSSascha Hauer } 33349525e5eSSascha Hauer 33449525e5eSSascha Hauer c->hash_len = crypto_shash_digestsize(c->hash_tfm); 33549525e5eSSascha Hauer if (c->hash_len > UBIFS_HASH_ARR_SZ) { 33649525e5eSSascha Hauer ubifs_err(c, "hash %s is bigger than maximum allowed hash size (%d > %d)", 33749525e5eSSascha Hauer c->auth_hash_name, c->hash_len, UBIFS_HASH_ARR_SZ); 33849525e5eSSascha Hauer err = -EINVAL; 33949525e5eSSascha Hauer goto out_free_hash; 34049525e5eSSascha Hauer } 34149525e5eSSascha Hauer 3423d234b33SEric Biggers c->hmac_tfm = crypto_alloc_shash(hmac_name, 0, 0); 34349525e5eSSascha Hauer if (IS_ERR(c->hmac_tfm)) { 34449525e5eSSascha Hauer err = PTR_ERR(c->hmac_tfm); 34549525e5eSSascha Hauer ubifs_err(c, "Can not allocate %s: %d", hmac_name, err); 34649525e5eSSascha Hauer goto out_free_hash; 34749525e5eSSascha Hauer } 34849525e5eSSascha Hauer 34949525e5eSSascha Hauer c->hmac_desc_len = crypto_shash_digestsize(c->hmac_tfm); 35049525e5eSSascha Hauer if (c->hmac_desc_len > UBIFS_HMAC_ARR_SZ) { 35149525e5eSSascha Hauer ubifs_err(c, "hmac %s is bigger than maximum allowed hmac size (%d > %d)", 35249525e5eSSascha Hauer hmac_name, c->hmac_desc_len, UBIFS_HMAC_ARR_SZ); 35349525e5eSSascha Hauer err = -EINVAL; 35449525e5eSSascha Hauer goto out_free_hash; 35549525e5eSSascha Hauer } 35649525e5eSSascha Hauer 35749525e5eSSascha Hauer err = crypto_shash_setkey(c->hmac_tfm, ukp->data, ukp->datalen); 35849525e5eSSascha Hauer if (err) 35949525e5eSSascha Hauer goto out_free_hmac; 36049525e5eSSascha Hauer 36149525e5eSSascha Hauer c->authenticated = true; 36249525e5eSSascha Hauer 36349525e5eSSascha Hauer c->log_hash = ubifs_hash_get_desc(c); 36449525e5eSSascha Hauer if (IS_ERR(c->log_hash)) 36549525e5eSSascha Hauer goto out_free_hmac; 36649525e5eSSascha Hauer 36749525e5eSSascha Hauer err = 0; 36849525e5eSSascha Hauer 36949525e5eSSascha Hauer out_free_hmac: 37049525e5eSSascha Hauer if (err) 37149525e5eSSascha Hauer crypto_free_shash(c->hmac_tfm); 37249525e5eSSascha Hauer out_free_hash: 37349525e5eSSascha Hauer if (err) 37449525e5eSSascha Hauer crypto_free_shash(c->hash_tfm); 37549525e5eSSascha Hauer out: 37649525e5eSSascha Hauer up_read(&keyring_key->sem); 37749525e5eSSascha Hauer key_put(keyring_key); 37849525e5eSSascha Hauer 37949525e5eSSascha Hauer return err; 38049525e5eSSascha Hauer } 38149525e5eSSascha Hauer 38249525e5eSSascha Hauer /** 38349525e5eSSascha Hauer * __ubifs_exit_authentication - release resource 38449525e5eSSascha Hauer * @c: UBIFS file-system description object 38549525e5eSSascha Hauer * 38649525e5eSSascha Hauer * This function releases the authentication related resources. 38749525e5eSSascha Hauer */ 38849525e5eSSascha Hauer void __ubifs_exit_authentication(struct ubifs_info *c) 38949525e5eSSascha Hauer { 39049525e5eSSascha Hauer if (!ubifs_authenticated(c)) 39149525e5eSSascha Hauer return; 39249525e5eSSascha Hauer 39349525e5eSSascha Hauer crypto_free_shash(c->hmac_tfm); 39449525e5eSSascha Hauer crypto_free_shash(c->hash_tfm); 39549525e5eSSascha Hauer kfree(c->log_hash); 39649525e5eSSascha Hauer } 39749525e5eSSascha Hauer 39849525e5eSSascha Hauer /** 39949525e5eSSascha Hauer * ubifs_node_calc_hmac - calculate the HMAC of a UBIFS node 40049525e5eSSascha Hauer * @c: UBIFS file-system description object 40149525e5eSSascha Hauer * @node: the node to insert a HMAC into. 40249525e5eSSascha Hauer * @len: the length of the node 40349525e5eSSascha Hauer * @ofs_hmac: the offset in the node where the HMAC is inserted 40449525e5eSSascha Hauer * @hmac: returned HMAC 40549525e5eSSascha Hauer * 40649525e5eSSascha Hauer * This function calculates a HMAC of a UBIFS node. The HMAC is expected to be 40749525e5eSSascha Hauer * embedded into the node, so this area is not covered by the HMAC. Also not 40849525e5eSSascha Hauer * covered is the UBIFS_NODE_MAGIC and the CRC of the node. 40949525e5eSSascha Hauer */ 41049525e5eSSascha Hauer static int ubifs_node_calc_hmac(const struct ubifs_info *c, const void *node, 41149525e5eSSascha Hauer int len, int ofs_hmac, void *hmac) 41249525e5eSSascha Hauer { 41349525e5eSSascha Hauer SHASH_DESC_ON_STACK(shash, c->hmac_tfm); 41449525e5eSSascha Hauer int hmac_len = c->hmac_desc_len; 41549525e5eSSascha Hauer int err; 41649525e5eSSascha Hauer 41749525e5eSSascha Hauer ubifs_assert(c, ofs_hmac > 8); 41849525e5eSSascha Hauer ubifs_assert(c, ofs_hmac + hmac_len < len); 41949525e5eSSascha Hauer 42049525e5eSSascha Hauer shash->tfm = c->hmac_tfm; 42149525e5eSSascha Hauer 42249525e5eSSascha Hauer err = crypto_shash_init(shash); 42349525e5eSSascha Hauer if (err) 42449525e5eSSascha Hauer return err; 42549525e5eSSascha Hauer 42649525e5eSSascha Hauer /* behind common node header CRC up to HMAC begin */ 42749525e5eSSascha Hauer err = crypto_shash_update(shash, node + 8, ofs_hmac - 8); 42849525e5eSSascha Hauer if (err < 0) 42949525e5eSSascha Hauer return err; 43049525e5eSSascha Hauer 43149525e5eSSascha Hauer /* behind HMAC, if any */ 43249525e5eSSascha Hauer if (len - ofs_hmac - hmac_len > 0) { 43349525e5eSSascha Hauer err = crypto_shash_update(shash, node + ofs_hmac + hmac_len, 43449525e5eSSascha Hauer len - ofs_hmac - hmac_len); 43549525e5eSSascha Hauer if (err < 0) 43649525e5eSSascha Hauer return err; 43749525e5eSSascha Hauer } 43849525e5eSSascha Hauer 43949525e5eSSascha Hauer return crypto_shash_final(shash, hmac); 44049525e5eSSascha Hauer } 44149525e5eSSascha Hauer 44249525e5eSSascha Hauer /** 44349525e5eSSascha Hauer * __ubifs_node_insert_hmac - insert a HMAC into a UBIFS node 44449525e5eSSascha Hauer * @c: UBIFS file-system description object 44549525e5eSSascha Hauer * @node: the node to insert a HMAC into. 44649525e5eSSascha Hauer * @len: the length of the node 44749525e5eSSascha Hauer * @ofs_hmac: the offset in the node where the HMAC is inserted 44849525e5eSSascha Hauer * 44949525e5eSSascha Hauer * This function inserts a HMAC at offset @ofs_hmac into the node given in 45049525e5eSSascha Hauer * @node. 45149525e5eSSascha Hauer * 45249525e5eSSascha Hauer * This function returns 0 for success or a negative error code otherwise. 45349525e5eSSascha Hauer */ 45449525e5eSSascha Hauer int __ubifs_node_insert_hmac(const struct ubifs_info *c, void *node, int len, 45549525e5eSSascha Hauer int ofs_hmac) 45649525e5eSSascha Hauer { 45749525e5eSSascha Hauer return ubifs_node_calc_hmac(c, node, len, ofs_hmac, node + ofs_hmac); 45849525e5eSSascha Hauer } 45949525e5eSSascha Hauer 46049525e5eSSascha Hauer /** 46149525e5eSSascha Hauer * __ubifs_node_verify_hmac - verify the HMAC of UBIFS node 46249525e5eSSascha Hauer * @c: UBIFS file-system description object 46349525e5eSSascha Hauer * @node: the node to insert a HMAC into. 46449525e5eSSascha Hauer * @len: the length of the node 46549525e5eSSascha Hauer * @ofs_hmac: the offset in the node where the HMAC is inserted 46649525e5eSSascha Hauer * 46749525e5eSSascha Hauer * This function verifies the HMAC at offset @ofs_hmac of the node given in 46849525e5eSSascha Hauer * @node. Returns 0 if successful or a negative error code otherwise. 46949525e5eSSascha Hauer */ 47049525e5eSSascha Hauer int __ubifs_node_verify_hmac(const struct ubifs_info *c, const void *node, 47149525e5eSSascha Hauer int len, int ofs_hmac) 47249525e5eSSascha Hauer { 47349525e5eSSascha Hauer int hmac_len = c->hmac_desc_len; 47449525e5eSSascha Hauer u8 *hmac; 47549525e5eSSascha Hauer int err; 47649525e5eSSascha Hauer 47749525e5eSSascha Hauer hmac = kmalloc(hmac_len, GFP_NOFS); 47849525e5eSSascha Hauer if (!hmac) 47949525e5eSSascha Hauer return -ENOMEM; 48049525e5eSSascha Hauer 48149525e5eSSascha Hauer err = ubifs_node_calc_hmac(c, node, len, ofs_hmac, hmac); 4827992e004SWenwen Wang if (err) { 4837992e004SWenwen Wang kfree(hmac); 48449525e5eSSascha Hauer return err; 4857992e004SWenwen Wang } 48649525e5eSSascha Hauer 48749525e5eSSascha Hauer err = crypto_memneq(hmac, node + ofs_hmac, hmac_len); 48849525e5eSSascha Hauer 48949525e5eSSascha Hauer kfree(hmac); 49049525e5eSSascha Hauer 49149525e5eSSascha Hauer if (!err) 49249525e5eSSascha Hauer return 0; 49349525e5eSSascha Hauer 49449525e5eSSascha Hauer return -EPERM; 49549525e5eSSascha Hauer } 49649525e5eSSascha Hauer 49749525e5eSSascha Hauer int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src, 49849525e5eSSascha Hauer struct shash_desc *target) 49949525e5eSSascha Hauer { 50049525e5eSSascha Hauer u8 *state; 50149525e5eSSascha Hauer int err; 50249525e5eSSascha Hauer 50349525e5eSSascha Hauer state = kmalloc(crypto_shash_descsize(src->tfm), GFP_NOFS); 50449525e5eSSascha Hauer if (!state) 50549525e5eSSascha Hauer return -ENOMEM; 50649525e5eSSascha Hauer 50749525e5eSSascha Hauer err = crypto_shash_export(src, state); 50849525e5eSSascha Hauer if (err) 50949525e5eSSascha Hauer goto out; 51049525e5eSSascha Hauer 51149525e5eSSascha Hauer err = crypto_shash_import(target, state); 51249525e5eSSascha Hauer 51349525e5eSSascha Hauer out: 51449525e5eSSascha Hauer kfree(state); 51549525e5eSSascha Hauer 51649525e5eSSascha Hauer return err; 51749525e5eSSascha Hauer } 51849525e5eSSascha Hauer 51949525e5eSSascha Hauer /** 52049525e5eSSascha Hauer * ubifs_hmac_wkm - Create a HMAC of the well known message 52149525e5eSSascha Hauer * @c: UBIFS file-system description object 52249525e5eSSascha Hauer * @hmac: The HMAC of the well known message 52349525e5eSSascha Hauer * 52449525e5eSSascha Hauer * This function creates a HMAC of a well known message. This is used 52549525e5eSSascha Hauer * to check if the provided key is suitable to authenticate a UBIFS 52649525e5eSSascha Hauer * image. This is only a convenience to the user to provide a better 52749525e5eSSascha Hauer * error message when the wrong key is provided. 52849525e5eSSascha Hauer * 52949525e5eSSascha Hauer * This function returns 0 for success or a negative error code otherwise. 53049525e5eSSascha Hauer */ 53149525e5eSSascha Hauer int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac) 53249525e5eSSascha Hauer { 53349525e5eSSascha Hauer SHASH_DESC_ON_STACK(shash, c->hmac_tfm); 53449525e5eSSascha Hauer int err; 53549525e5eSSascha Hauer const char well_known_message[] = "UBIFS"; 53649525e5eSSascha Hauer 53749525e5eSSascha Hauer if (!ubifs_authenticated(c)) 53849525e5eSSascha Hauer return 0; 53949525e5eSSascha Hauer 54049525e5eSSascha Hauer shash->tfm = c->hmac_tfm; 54149525e5eSSascha Hauer 54249525e5eSSascha Hauer err = crypto_shash_init(shash); 54349525e5eSSascha Hauer if (err) 54449525e5eSSascha Hauer return err; 54549525e5eSSascha Hauer 54649525e5eSSascha Hauer err = crypto_shash_update(shash, well_known_message, 54749525e5eSSascha Hauer sizeof(well_known_message) - 1); 54849525e5eSSascha Hauer if (err < 0) 54949525e5eSSascha Hauer return err; 55049525e5eSSascha Hauer 55149525e5eSSascha Hauer err = crypto_shash_final(shash, hmac); 55249525e5eSSascha Hauer if (err) 55349525e5eSSascha Hauer return err; 55449525e5eSSascha Hauer return 0; 55549525e5eSSascha Hauer } 556817aa094SSascha Hauer 557817aa094SSascha Hauer /* 558817aa094SSascha Hauer * ubifs_hmac_zero - test if a HMAC is zero 559817aa094SSascha Hauer * @c: UBIFS file-system description object 560817aa094SSascha Hauer * @hmac: the HMAC to test 561817aa094SSascha Hauer * 562817aa094SSascha Hauer * This function tests if a HMAC is zero and returns true if it is 563817aa094SSascha Hauer * and false otherwise. 564817aa094SSascha Hauer */ 565817aa094SSascha Hauer bool ubifs_hmac_zero(struct ubifs_info *c, const u8 *hmac) 566817aa094SSascha Hauer { 567817aa094SSascha Hauer return !memchr_inv(hmac, 0, c->hmac_desc_len); 568817aa094SSascha Hauer } 569