From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- fs/ubifs/auth.c | 546 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 546 insertions(+) create mode 100644 fs/ubifs/auth.c (limited to 'fs/ubifs/auth.c') diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c new file mode 100644 index 000000000..e564d5ff8 --- /dev/null +++ b/fs/ubifs/auth.c @@ -0,0 +1,546 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file is part of UBIFS. + * + * Copyright (C) 2018 Pengutronix, Sascha Hauer + */ + +/* + * This file implements various helper functions for UBIFS authentication support + */ + +#include +#include +#include +#include +#include +#include + +#include "ubifs.h" + +/** + * ubifs_node_calc_hash - calculate the hash of a UBIFS node + * @c: UBIFS file-system description object + * @node: the node to calculate a hash for + * @hash: the returned hash + * + * Returns 0 for success or a negative error code otherwise. + */ +int __ubifs_node_calc_hash(const struct ubifs_info *c, const void *node, + u8 *hash) +{ + const struct ubifs_ch *ch = node; + + return crypto_shash_tfm_digest(c->hash_tfm, node, le32_to_cpu(ch->len), + hash); +} + +/** + * ubifs_hash_calc_hmac - calculate a HMAC from a hash + * @c: UBIFS file-system description object + * @hash: the node to calculate a HMAC for + * @hmac: the returned HMAC + * + * Returns 0 for success or a negative error code otherwise. + */ +static int ubifs_hash_calc_hmac(const struct ubifs_info *c, const u8 *hash, + u8 *hmac) +{ + return crypto_shash_tfm_digest(c->hmac_tfm, hash, c->hash_len, hmac); +} + +/** + * ubifs_prepare_auth_node - Prepare an authentication node + * @c: UBIFS file-system description object + * @node: the node to calculate a hash for + * @inhash: input hash of previous nodes + * + * This function prepares an authentication node for writing onto flash. + * It creates a HMAC from the given input hash and writes it to the node. + * + * Returns 0 for success or a negative error code otherwise. + */ +int ubifs_prepare_auth_node(struct ubifs_info *c, void *node, + struct shash_desc *inhash) +{ + struct ubifs_auth_node *auth = node; + u8 hash[UBIFS_HASH_ARR_SZ]; + int err; + + { + SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm); + + hash_desc->tfm = c->hash_tfm; + ubifs_shash_copy_state(c, inhash, hash_desc); + + err = crypto_shash_final(hash_desc, hash); + if (err) + return err; + } + + err = ubifs_hash_calc_hmac(c, hash, auth->hmac); + if (err) + return err; + + auth->ch.node_type = UBIFS_AUTH_NODE; + ubifs_prepare_node(c, auth, ubifs_auth_node_sz(c), 0); + return 0; +} + +static struct shash_desc *ubifs_get_desc(const struct ubifs_info *c, + struct crypto_shash *tfm) +{ + struct shash_desc *desc; + int err; + + if (!ubifs_authenticated(c)) + return NULL; + + desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(tfm), GFP_KERNEL); + if (!desc) + return ERR_PTR(-ENOMEM); + + desc->tfm = tfm; + + err = crypto_shash_init(desc); + if (err) { + kfree(desc); + return ERR_PTR(err); + } + + return desc; +} + +/** + * __ubifs_hash_get_desc - get a descriptor suitable for hashing a node + * @c: UBIFS file-system description object + * + * This function returns a descriptor suitable for hashing a node. Free after use + * with kfree. + */ +struct shash_desc *__ubifs_hash_get_desc(const struct ubifs_info *c) +{ + return ubifs_get_desc(c, c->hash_tfm); +} + +/** + * ubifs_bad_hash - Report hash mismatches + * @c: UBIFS file-system description object + * @node: the node + * @hash: the expected hash + * @lnum: the LEB @node was read from + * @offs: offset in LEB @node was read from + * + * This function reports a hash mismatch when a node has a different hash than + * expected. + */ +void ubifs_bad_hash(const struct ubifs_info *c, const void *node, const u8 *hash, + int lnum, int offs) +{ + int len = min(c->hash_len, 20); + int cropped = len != c->hash_len; + const char *cont = cropped ? "..." : ""; + + u8 calc[UBIFS_HASH_ARR_SZ]; + + __ubifs_node_calc_hash(c, node, calc); + + ubifs_err(c, "hash mismatch on node at LEB %d:%d", lnum, offs); + ubifs_err(c, "hash expected: %*ph%s", len, hash, cont); + ubifs_err(c, "hash calculated: %*ph%s", len, calc, cont); +} + +/** + * __ubifs_node_check_hash - check the hash of a node against given hash + * @c: UBIFS file-system description object + * @node: the node + * @expected: the expected hash + * + * This function calculates a hash over a node and compares it to the given hash. + * Returns 0 if both hashes are equal or authentication is disabled, otherwise a + * negative error code is returned. + */ +int __ubifs_node_check_hash(const struct ubifs_info *c, const void *node, + const u8 *expected) +{ + u8 calc[UBIFS_HASH_ARR_SZ]; + int err; + + err = __ubifs_node_calc_hash(c, node, calc); + if (err) + return err; + + if (ubifs_check_hash(c, expected, calc)) + return -EPERM; + + return 0; +} + +/** + * ubifs_sb_verify_signature - verify the signature of a superblock + * @c: UBIFS file-system description object + * @sup: The superblock node + * + * To support offline signed images the superblock can be signed with a + * PKCS#7 signature. The signature is placed directly behind the superblock + * node in an ubifs_sig_node. + * + * Returns 0 when the signature can be successfully verified or a negative + * error code if not. + */ +int ubifs_sb_verify_signature(struct ubifs_info *c, + const struct ubifs_sb_node *sup) +{ + int err; + struct ubifs_scan_leb *sleb; + struct ubifs_scan_node *snod; + const struct ubifs_sig_node *signode; + + sleb = ubifs_scan(c, UBIFS_SB_LNUM, UBIFS_SB_NODE_SZ, c->sbuf, 0); + if (IS_ERR(sleb)) { + err = PTR_ERR(sleb); + return err; + } + + if (sleb->nodes_cnt == 0) { + ubifs_err(c, "Unable to find signature node"); + err = -EINVAL; + goto out_destroy; + } + + snod = list_first_entry(&sleb->nodes, struct ubifs_scan_node, list); + + if (snod->type != UBIFS_SIG_NODE) { + ubifs_err(c, "Signature node is of wrong type"); + err = -EINVAL; + goto out_destroy; + } + + signode = snod->node; + + if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) { + ubifs_err(c, "invalid signature len %d", le32_to_cpu(signode->len)); + err = -EINVAL; + goto out_destroy; + } + + if (le32_to_cpu(signode->type) != UBIFS_SIGNATURE_TYPE_PKCS7) { + ubifs_err(c, "Signature type %d is not supported\n", + le32_to_cpu(signode->type)); + err = -EINVAL; + goto out_destroy; + } + + err = verify_pkcs7_signature(sup, sizeof(struct ubifs_sb_node), + signode->sig, le32_to_cpu(signode->len), + NULL, VERIFYING_UNSPECIFIED_SIGNATURE, + NULL, NULL); + + if (err) + ubifs_err(c, "Failed to verify signature"); + else + ubifs_msg(c, "Successfully verified super block signature"); + +out_destroy: + ubifs_scan_destroy(sleb); + + return err; +} + +/** + * ubifs_init_authentication - initialize UBIFS authentication support + * @c: UBIFS file-system description object + * + * This function returns 0 for success or a negative error code otherwise. + */ +int ubifs_init_authentication(struct ubifs_info *c) +{ + struct key *keyring_key; + const struct user_key_payload *ukp; + int err; + char hmac_name[CRYPTO_MAX_ALG_NAME]; + + if (!c->auth_hash_name) { + ubifs_err(c, "authentication hash name needed with authentication"); + return -EINVAL; + } + + c->auth_hash_algo = match_string(hash_algo_name, HASH_ALGO__LAST, + c->auth_hash_name); + if ((int)c->auth_hash_algo < 0) { + ubifs_err(c, "Unknown hash algo %s specified", + c->auth_hash_name); + return -EINVAL; + } + + snprintf(hmac_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)", + c->auth_hash_name); + + keyring_key = request_key(&key_type_logon, c->auth_key_name, NULL); + + if (IS_ERR(keyring_key)) { + ubifs_err(c, "Failed to request key: %ld", + PTR_ERR(keyring_key)); + return PTR_ERR(keyring_key); + } + + down_read(&keyring_key->sem); + + if (keyring_key->type != &key_type_logon) { + ubifs_err(c, "key type must be logon"); + err = -ENOKEY; + goto out; + } + + ukp = user_key_payload_locked(keyring_key); + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + err = -EKEYREVOKED; + goto out; + } + + c->hash_tfm = crypto_alloc_shash(c->auth_hash_name, 0, 0); + if (IS_ERR(c->hash_tfm)) { + err = PTR_ERR(c->hash_tfm); + ubifs_err(c, "Can not allocate %s: %d", + c->auth_hash_name, err); + goto out; + } + + c->hash_len = crypto_shash_digestsize(c->hash_tfm); + if (c->hash_len > UBIFS_HASH_ARR_SZ) { + ubifs_err(c, "hash %s is bigger than maximum allowed hash size (%d > %d)", + c->auth_hash_name, c->hash_len, UBIFS_HASH_ARR_SZ); + err = -EINVAL; + goto out_free_hash; + } + + c->hmac_tfm = crypto_alloc_shash(hmac_name, 0, 0); + if (IS_ERR(c->hmac_tfm)) { + err = PTR_ERR(c->hmac_tfm); + ubifs_err(c, "Can not allocate %s: %d", hmac_name, err); + goto out_free_hash; + } + + c->hmac_desc_len = crypto_shash_digestsize(c->hmac_tfm); + if (c->hmac_desc_len > UBIFS_HMAC_ARR_SZ) { + ubifs_err(c, "hmac %s is bigger than maximum allowed hmac size (%d > %d)", + hmac_name, c->hmac_desc_len, UBIFS_HMAC_ARR_SZ); + err = -EINVAL; + goto out_free_hmac; + } + + err = crypto_shash_setkey(c->hmac_tfm, ukp->data, ukp->datalen); + if (err) + goto out_free_hmac; + + c->authenticated = true; + + c->log_hash = ubifs_hash_get_desc(c); + if (IS_ERR(c->log_hash)) { + err = PTR_ERR(c->log_hash); + goto out_free_hmac; + } + + err = 0; + +out_free_hmac: + if (err) + crypto_free_shash(c->hmac_tfm); +out_free_hash: + if (err) + crypto_free_shash(c->hash_tfm); +out: + up_read(&keyring_key->sem); + key_put(keyring_key); + + return err; +} + +/** + * __ubifs_exit_authentication - release resource + * @c: UBIFS file-system description object + * + * This function releases the authentication related resources. + */ +void __ubifs_exit_authentication(struct ubifs_info *c) +{ + if (!ubifs_authenticated(c)) + return; + + crypto_free_shash(c->hmac_tfm); + crypto_free_shash(c->hash_tfm); + kfree(c->log_hash); +} + +/** + * ubifs_node_calc_hmac - calculate the HMAC of a UBIFS node + * @c: UBIFS file-system description object + * @node: the node to insert a HMAC into. + * @len: the length of the node + * @ofs_hmac: the offset in the node where the HMAC is inserted + * @hmac: returned HMAC + * + * This function calculates a HMAC of a UBIFS node. The HMAC is expected to be + * embedded into the node, so this area is not covered by the HMAC. Also not + * covered is the UBIFS_NODE_MAGIC and the CRC of the node. + */ +static int ubifs_node_calc_hmac(const struct ubifs_info *c, const void *node, + int len, int ofs_hmac, void *hmac) +{ + SHASH_DESC_ON_STACK(shash, c->hmac_tfm); + int hmac_len = c->hmac_desc_len; + int err; + + ubifs_assert(c, ofs_hmac > 8); + ubifs_assert(c, ofs_hmac + hmac_len < len); + + shash->tfm = c->hmac_tfm; + + err = crypto_shash_init(shash); + if (err) + return err; + + /* behind common node header CRC up to HMAC begin */ + err = crypto_shash_update(shash, node + 8, ofs_hmac - 8); + if (err < 0) + return err; + + /* behind HMAC, if any */ + if (len - ofs_hmac - hmac_len > 0) { + err = crypto_shash_update(shash, node + ofs_hmac + hmac_len, + len - ofs_hmac - hmac_len); + if (err < 0) + return err; + } + + return crypto_shash_final(shash, hmac); +} + +/** + * __ubifs_node_insert_hmac - insert a HMAC into a UBIFS node + * @c: UBIFS file-system description object + * @node: the node to insert a HMAC into. + * @len: the length of the node + * @ofs_hmac: the offset in the node where the HMAC is inserted + * + * This function inserts a HMAC at offset @ofs_hmac into the node given in + * @node. + * + * This function returns 0 for success or a negative error code otherwise. + */ +int __ubifs_node_insert_hmac(const struct ubifs_info *c, void *node, int len, + int ofs_hmac) +{ + return ubifs_node_calc_hmac(c, node, len, ofs_hmac, node + ofs_hmac); +} + +/** + * __ubifs_node_verify_hmac - verify the HMAC of UBIFS node + * @c: UBIFS file-system description object + * @node: the node to insert a HMAC into. + * @len: the length of the node + * @ofs_hmac: the offset in the node where the HMAC is inserted + * + * This function verifies the HMAC at offset @ofs_hmac of the node given in + * @node. Returns 0 if successful or a negative error code otherwise. + */ +int __ubifs_node_verify_hmac(const struct ubifs_info *c, const void *node, + int len, int ofs_hmac) +{ + int hmac_len = c->hmac_desc_len; + u8 *hmac; + int err; + + hmac = kmalloc(hmac_len, GFP_NOFS); + if (!hmac) + return -ENOMEM; + + err = ubifs_node_calc_hmac(c, node, len, ofs_hmac, hmac); + if (err) { + kfree(hmac); + return err; + } + + err = crypto_memneq(hmac, node + ofs_hmac, hmac_len); + + kfree(hmac); + + if (!err) + return 0; + + return -EPERM; +} + +int __ubifs_shash_copy_state(const struct ubifs_info *c, struct shash_desc *src, + struct shash_desc *target) +{ + u8 *state; + int err; + + state = kmalloc(crypto_shash_descsize(src->tfm), GFP_NOFS); + if (!state) + return -ENOMEM; + + err = crypto_shash_export(src, state); + if (err) + goto out; + + err = crypto_shash_import(target, state); + +out: + kfree(state); + + return err; +} + +/** + * ubifs_hmac_wkm - Create a HMAC of the well known message + * @c: UBIFS file-system description object + * @hmac: The HMAC of the well known message + * + * This function creates a HMAC of a well known message. This is used + * to check if the provided key is suitable to authenticate a UBIFS + * image. This is only a convenience to the user to provide a better + * error message when the wrong key is provided. + * + * This function returns 0 for success or a negative error code otherwise. + */ +int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac) +{ + SHASH_DESC_ON_STACK(shash, c->hmac_tfm); + int err; + const char well_known_message[] = "UBIFS"; + + if (!ubifs_authenticated(c)) + return 0; + + shash->tfm = c->hmac_tfm; + + err = crypto_shash_init(shash); + if (err) + return err; + + err = crypto_shash_update(shash, well_known_message, + sizeof(well_known_message) - 1); + if (err < 0) + return err; + + err = crypto_shash_final(shash, hmac); + if (err) + return err; + return 0; +} + +/* + * ubifs_hmac_zero - test if a HMAC is zero + * @c: UBIFS file-system description object + * @hmac: the HMAC to test + * + * This function tests if a HMAC is zero and returns true if it is + * and false otherwise. + */ +bool ubifs_hmac_zero(struct ubifs_info *c, const u8 *hmac) +{ + return !memchr_inv(hmac, 0, c->hmac_desc_len); +} -- cgit v1.2.3