/** * eCryptfs: Linux filesystem encryption layer * In-kernel key management code. Includes functions to parse and * write authentication token-related packets with the underlying * file. * * Copyright (C) 2004-2006 International Business Machines Corp. * Author(s): Michael A. Halcrow * Michael C. Thompson * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA * 02111-1307, USA. */ #include #include #include #include #include #include #include #include #include "ecryptfs_kernel.h" /** * request_key returned an error instead of a valid key address; * determine the type of error, make appropriate log entries, and * return an error code. */ int process_request_key_err(long err_code) { int rc = 0; switch (err_code) { case ENOKEY: ecryptfs_printk(KERN_WARNING, "No key\n"); rc = -ENOENT; break; case EKEYEXPIRED: ecryptfs_printk(KERN_WARNING, "Key expired\n"); rc = -ETIME; break; case EKEYREVOKED: ecryptfs_printk(KERN_WARNING, "Key revoked\n"); rc = -EINVAL; break; default: ecryptfs_printk(KERN_WARNING, "Unknown error code: " "[0x%.16x]\n", err_code); rc = -EINVAL; } return rc; } static void wipe_auth_tok_list(struct list_head *auth_tok_list_head) { struct list_head *walker; struct ecryptfs_auth_tok_list_item *auth_tok_list_item; walker = auth_tok_list_head->next; while (walker != auth_tok_list_head) { auth_tok_list_item = list_entry(walker, struct ecryptfs_auth_tok_list_item, list); walker = auth_tok_list_item->list.next; memset(auth_tok_list_item, 0, sizeof(struct ecryptfs_auth_tok_list_item)); kmem_cache_free(ecryptfs_auth_tok_list_item_cache, auth_tok_list_item); } } struct kmem_cache *ecryptfs_auth_tok_list_item_cache; /** * parse_packet_length * @data: Pointer to memory containing length at offset * @size: This function writes the decoded size to this memory * address; zero on error * @length_size: The number of bytes occupied by the encoded length * * Returns Zero on success */ static int parse_packet_length(unsigned char *data, size_t *size, size_t *length_size) { int rc = 0; (*length_size) = 0; (*size) = 0; if (data[0] < 192) { /* One-byte length */ (*size) = data[0]; (*length_size) = 1; } else if (data[0] < 224) { /* Two-byte length */ (*size) = ((data[0] - 192) * 256); (*size) += (data[1] + 192); (*length_size) = 2; } else if (data[0] == 255) { /* Five-byte length; we're not supposed to see this */ ecryptfs_printk(KERN_ERR, "Five-byte packet length not " "supported\n"); rc = -EINVAL; goto out; } else { ecryptfs_printk(KERN_ERR, "Error parsing packet length\n"); rc = -EINVAL; goto out; } out: return rc; } /** * write_packet_length * @dest: The byte array target into which to write the * length. Must have at least 5 bytes allocated. * @size: The length to write. * @packet_size_length: The number of bytes used to encode the * packet length is written to this address. * * Returns zero on success; non-zero on error. */ static int write_packet_length(char *dest, size_t size, size_t *packet_size_length) { int rc = 0; if (size < 192) { dest[0] = size; (*packet_size_length) = 1; } else if (size < 65536) { dest[0] = (((size - 192) / 256) + 192); dest[1] = ((size - 192) % 256); (*packet_size_length) = 2; } else { rc = -EINVAL; ecryptfs_printk(KERN_WARNING, "Unsupported packet size: [%d]\n", size); } return rc; } /** * parse_tag_3_packet * @crypt_stat: The cryptographic context to modify based on packet * contents. * @data: The raw bytes of the packet. * @auth_tok_list: eCryptfs parses packets into authentication tokens; * a new authentication token will be placed at the end * of this list for this packet. * @new_auth_tok: Pointer to a pointer to memory that this function * allocates; sets the memory address of the pointer to * NULL on error. This object is added to the * auth_tok_list. * @packet_size: This function writes the size of the parsed packet * into this memory location; zero on error. * @max_packet_size: maximum number of bytes to parse * * Returns zero on success; non-zero on error. */ static int parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat, unsigned char *data, struct list_head *auth_tok_list, struct ecryptfs_auth_tok **new_auth_tok, size_t *packet_size, size_t max_packet_size) { int rc = 0; size_t body_size; struct ecryptfs_auth_tok_list_item *auth_tok_list_item; size_t length_size; (*packet_size) = 0; (*new_auth_tok) = NULL; /* we check that: * one byte for the Tag 3 ID flag * two bytes for the body size * do not exceed the maximum_packet_size */ if (unlikely((*packet_size) + 3 > max_packet_size)) { ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); rc = -EINVAL; goto out; } /* check for Tag 3 identifyer - one byte */ if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) { ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n", ECRYPTFS_TAG_3_PACKET_TYPE); rc = -EINVAL; goto out; } /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or * at end of function upon failure */ auth_tok_list_item = kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL); if (!auth_tok_list_item) { ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n"); rc = -ENOMEM; goto out; } memset(auth_tok_list_item, 0, sizeof(struct ecryptfs_auth_tok_list_item)); (*new_auth_tok) = &auth_tok_list_item->auth_tok; /* check for body size - one to two bytes */ rc = parse_packet_length(&data[(*packet_size)], &body_size, &length_size); if (rc) { ecryptfs_printk(KERN_WARNING, "Error parsing packet length; " "rc = [%d]\n", rc); goto out_free; } if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) { ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n", body_size); rc = -EINVAL; goto out_free; } (*packet_size) += length_size; /* now we know the length of the remainting Tag 3 packet size: * 5 fix bytes for: version string, cipher, S2K ID, hash algo, * number of hash iterations * ECRYPTFS_SALT_SIZE bytes for salt * body_size bytes minus the stuff above is the encrypted key size */ if (unlikely((*packet_size) + body_size > max_packet_size)) { ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); rc = -EINVAL; goto out_free; } /* There are 5 characters of additional information in the * packet */ (*new_auth_tok)->session_key.encrypted_key_size = body_size - (0x05 + ECRYPTFS_SALT_SIZE); ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n", (*new_auth_tok)->session_key.encrypted_key_size); /* Version 4 (from RFC2440) - one byte */ if (unlikely(data[(*packet_size)++] != 0x04)) { ecryptfs_printk(KERN_DEBUG, "Unknown version number " "[%d]\n", data[(*packet_size) - 1]); rc = -EINVAL; goto out_free; } /* cipher - one byte */ ecryptfs_cipher_code_to_string(crypt_stat->cipher, (u16)data[(*packet_size)]); /* A little extra work to differentiate among the AES key * sizes; see RFC2440 */ switch(data[(*packet_size)++]) { case RFC2440_CIPHER_AES_192: crypt_stat->key_size = 24; break; default: crypt_stat->key_size = (*new_auth_tok)->session_key.encrypted_key_size; } ecryptfs_init_crypt_ctx(crypt_stat); /* S2K identifier 3 (from RFC2440) */ if (unlikely(data[(*packet_size)++] != 0x03)) { ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently " "supported\n"); rc = -ENOSYS; goto out_free; } /* TODO: finish the hash mapping */ /* hash algorithm - one byte */ switch (data[(*packet_size)++]) { case 0x01: /* See RFC2440 for these numbers and their mappings */ /* Choose MD5 */ /* salt - ECRYPTFS_SALT_SIZE bytes */ memcpy((*new_auth_tok)->token.password.salt, &data[(*packet_size)], ECRYPTFS_SALT_SIZE); (*packet_size) += ECRYPTFS_SALT_SIZE; /* This conversion was taken straight from RFC2440 */ /* number of hash iterations - one byte */ (*new_auth_tok)->token.password.hash_iterations = ((u32) 16 + (data[(*packet_size)] & 15)) << ((data[(*packet_size)] >> 4) + 6); (*packet_size)++; /* encrypted session key - * (body_size-5-ECRYPTFS_SALT_SIZE) bytes */ memcpy((*new_auth_tok)->session_key.encrypted_key, &data[(*packet_size)], (*new_auth_tok)->session_key.encrypted_key_size); (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size; (*new_auth_tok)->session_key.flags &= ~ECRYPTFS_CONTAINS_DECRYPTED_KEY; (*new_auth_tok)->session_key.flags |= ECRYPTFS_CONTAINS_ENCRYPTED_KEY; (*new_auth_tok)->token.password.hash_algo = 0x01; break; default: ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: " "[%d]\n", data[(*packet_size) - 1]); rc = -ENOSYS; goto out_free; } (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD; /* TODO: Parametarize; we might actually want userspace to * decrypt the session key. */ ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags, ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT); ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags, ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT); list_add(&auth_tok_list_item->list, auth_tok_list); goto out; out_free: (*new_auth_tok) = NULL; memset(auth_tok_list_item, 0, sizeof(struct ecryptfs_auth_tok_list_item)); kmem_cache_free(ecryptfs_auth_tok_list_item_cache, auth_tok_list_item); out: if (rc) (*packet_size) = 0; return rc; } /** * parse_tag_11_packet * @data: The raw bytes of the packet * @contents: This function writes the data contents of the literal * packet into this memory location * @max_contents_bytes: The maximum number of bytes that this function * is allowed to write into contents * @tag_11_contents_size: This function writes the size of the parsed * contents into this memory location; zero on * error * @packet_size: This function writes the size of the parsed packet * into this memory location; zero on error * @max_packet_size: maximum number of bytes to parse * * Returns zero on success; non-zero on error. */ static int parse_tag_11_packet(unsigned char *data, unsigned char *contents, size_t max_contents_bytes, size_t *tag_11_contents_size, size_t *packet_size, size_t max_packet_size) { int rc = 0; size_t body_size; size_t length_size; (*packet_size) = 0; (*tag_11_contents_size) = 0; /* check that: * one byte for the Tag 11 ID flag * two bytes for the Tag 11 length * do not exceed the maximum_packet_size */ if (unlikely((*packet_size) + 3 > max_packet_size)) { ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); rc = -EINVAL; goto out; } /* check for Tag 11 identifyer - one byte */ if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) { ecryptfs_printk(KERN_WARNING, "Invalid tag 11 packet format\n"); rc = -EINVAL; goto out; } /* get Tag 11 content length - one or two bytes */ rc = parse_packet_length(&data[(*packet_size)], &body_size, &length_size); if (rc) { ecryptfs_printk(KERN_WARNING, "Invalid tag 11 packet format\n"); goto out; } (*packet_size) += length_size; if (body_size < 13) { ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n", body_size); rc = -EINVAL; goto out; } /* We have 13 bytes of surrounding packet values */ (*tag_11_contents_size) = (body_size - 13); /* now we know the length of the remainting Tag 11 packet size: * 14 fix bytes for: special flag one, special flag two, * 12 skipped bytes * body_size bytes minus the stuff above is the Tag 11 content */ /* FIXME why is the body size one byte smaller than the actual * size of the body? * this seems to be an error here as well as in * write_tag_11_packet() */ if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) { ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n"); rc = -EINVAL; goto out; } /* special flag one - one byte */ if (data[(*packet_size)++] != 0x62) { ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n"); rc = -EINVAL; goto out; } /* special flag two - one byte */ if (data[(*packet_size)++] != 0x08) { ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n"); rc = -EINVAL; goto out; } /* skip the next 12 bytes */ (*packet_size) += 12; /* We don't care about the filename or * the timestamp */ /* get the Tag 11 contents - tag_11_contents_size bytes */ memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size)); (*packet_size) += (*tag_11_contents_size); out: if (rc) { (*packet_size) = 0; (*tag_11_contents_size) = 0; } return rc; } /** * decrypt_session_key - Decrypt the session key with the given auth_tok. * * Returns Zero on success; non-zero error otherwise. */ static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok, struct ecryptfs_crypt_stat *crypt_stat) { struct ecryptfs_password *password_s_ptr; struct scatterlist src_sg[2], dst_sg[2]; struct mutex *tfm_mutex = NULL; /* TODO: Use virt_to_scatterlist for these */ char *encrypted_session_key; char *session_key; struct blkcipher_desc desc = { .flags = CRYPTO_TFM_REQ_MAY_SLEEP }; int rc = 0; password_s_ptr = &auth_tok->token.password; if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags, ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) ecryptfs_printk(KERN_DEBUG, "Session key encryption key " "set; skipping key generation\n"); ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])" ":\n", password_s_ptr->session_key_encryption_key_bytes); if (ecryptfs_verbosity > 0) ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key, password_s_ptr-> session_key_encryption_key_bytes); if (!strcmp(crypt_stat->cipher, crypt_stat->mount_crypt_stat->global_default_cipher_name) && crypt_stat->mount_crypt_stat->global_key_tfm) { desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm; tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; } else { char *full_alg_name; rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, crypt_stat->cipher, "ecb"); if (rc) goto out; desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC); kfree(full_alg_name); if (IS_ERR(desc.tfm)) { rc = PTR_ERR(desc.tfm); printk(KERN_ERR "Error allocating crypto context; " "rc = [%d]\n", rc); goto out; } crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY); } if (tfm_mutex) mutex_lock(tfm_mutex); rc = crypto_blkcipher_setkey(desc.tfm, password_s_ptr->session_key_encryption_key, crypt_stat->key_size); if (rc < 0) { printk(KERN_ERR "Error setting key for crypto context\n"); rc = -EINVAL; goto out_free_tfm; } /* TODO: virt_to_scatterlist */ encrypted_session_key = (char *)__get_free_page(GFP_KERNEL); if (!encrypted_session_key) { ecryptfs_printk(KERN_ERR, "Out of memory\n"); rc = -ENOMEM; goto out_free_tfm; } session_key = (char *)__get_free_page(GFP_KERNEL); if (!session_key) { kfree(encrypted_session_key); ecryptfs_printk(KERN_ERR, "Out of memory\n"); rc = -ENOMEM; goto out_free_tfm; } memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key, auth_tok->session_key.encrypted_key_size); src_sg[0].page = virt_to_page(encrypted_session_key); src_sg[0].offset = 0; BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE); src_sg[0].length = auth_tok->session_key.encrypted_key_size; dst_sg[0].page = virt_to_page(session_key); dst_sg[0].offset = 0; auth_tok->session_key.decrypted_key_size = auth_tok->session_key.encrypted_key_size; dst_sg[0].length = auth_tok->session_key.encrypted_key_size; rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg, auth_tok->session_key.encrypted_key_size); if (rc) { printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc); goto out_free_memory; } auth_tok->session_key.decrypted_key_size = auth_tok->session_key.encrypted_key_size; memcpy(auth_tok->session_key.decrypted_key, session_key, auth_tok->session_key.decrypted_key_size); auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY; memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key, auth_tok->session_key.decrypted_key_size); ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n"); if (ecryptfs_verbosity > 0) ecryptfs_dump_hex(crypt_stat->key, crypt_stat->key_size); out_free_memory: memset(encrypted_session_key, 0, PAGE_CACHE_SIZE); free_page((unsigned long)encrypted_session_key); memset(session_key, 0, PAGE_CACHE_SIZE); free_page((unsigned long)session_key); out_free_tfm: if (tfm_mutex) mutex_unlock(tfm_mutex); else crypto_free_blkcipher(desc.tfm); out: return rc; } /** * ecryptfs_parse_packet_set * @dest: The header page in memory * @version: Version of file format, to guide parsing behavior * * Get crypt_stat to have the file's session key if the requisite key * is available to decrypt the session key. * * Returns Zero if a valid authentication token was retrieved and * processed; negative value for file not encrypted or for error * conditions. */ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat, unsigned char *src, struct dentry *ecryptfs_dentry) { size_t i = 0; int rc = 0; size_t found_auth_tok = 0; size_t next_packet_is_auth_tok_packet; char sig[ECRYPTFS_SIG_SIZE_HEX]; struct list_head auth_tok_list; struct list_head *walker; struct ecryptfs_auth_tok *chosen_auth_tok = NULL; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = &ecryptfs_superblock_to_private( ecryptfs_dentry->d_sb)->mount_crypt_stat; struct ecryptfs_auth_tok *candidate_auth_tok = NULL; size_t packet_size; struct ecryptfs_auth_tok *new_auth_tok; unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE]; size_t tag_11_contents_size; size_t tag_11_packet_size; INIT_LIST_HEAD(&auth_tok_list); /* Parse the header to find as many packets as we can, these will be * added the our &auth_tok_list */ next_packet_is_auth_tok_packet = 1; while (next_packet_is_auth_tok_packet) { size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i); switch (src[i]) { case ECRYPTFS_TAG_3_PACKET_TYPE: rc = parse_tag_3_packet(crypt_stat, (unsigned char *)&src[i], &auth_tok_list, &new_auth_tok, &packet_size, max_packet_size); if (rc) { ecryptfs_printk(KERN_ERR, "Error parsing " "tag 3 packet\n"); rc = -EIO; goto out_wipe_list; } i += packet_size; rc = parse_tag_11_packet((unsigned char *)&src[i], sig_tmp_space, ECRYPTFS_SIG_SIZE, &tag_11_contents_size, &tag_11_packet_size, max_packet_size); if (rc) { ecryptfs_printk(KERN_ERR, "No valid " "(ecryptfs-specific) literal " "packet containing " "authentication token " "signature found after " "tag 3 packet\n"); rc = -EIO; goto out_wipe_list; } i += tag_11_packet_size; if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) { ecryptfs_printk(KERN_ERR, "Expected " "signature of size [%d]; " "read size [%d]\n", ECRYPTFS_SIG_SIZE, tag_11_contents_size); rc = -EIO; goto out_wipe_list; } ecryptfs_to_hex(new_auth_tok->token.password.signature, sig_tmp_space, tag_11_contents_size); new_auth_tok->token.password.signature[ ECRYPTFS_PASSWORD_SIG_SIZE] = '\0'; ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED); break; case ECRYPTFS_TAG_11_PACKET_TYPE: ecryptfs_printk(KERN_WARNING, "Invalid packet set " "(Tag 11 not allowed by itself)\n"); rc = -EIO; goto out_wipe_list; break; default: ecryptfs_printk(KERN_DEBUG, "No packet at offset " "[%d] of the file header; hex value of " "character is [0x%.2x]\n", i, src[i]); next_packet_is_auth_tok_packet = 0; } } if (list_empty(&auth_tok_list)) { rc = -EINVAL; /* Do not support non-encrypted files in * the 0.1 release */ goto out; } /* If we have a global auth tok, then we should try to use * it */ if (mount_crypt_stat->global_auth_tok) { memcpy(sig, mount_crypt_stat->global_auth_tok_sig, ECRYPTFS_SIG_SIZE_HEX); chosen_auth_tok = mount_crypt_stat->global_auth_tok; } else BUG(); /* We should always have a global auth tok in * the 0.1 release */ /* Scan list to see if our chosen_auth_tok works */ list_for_each(walker, &auth_tok_list) { struct ecryptfs_auth_tok_list_item *auth_tok_list_item; auth_tok_list_item = list_entry(walker, struct ecryptfs_auth_tok_list_item, list); candidate_auth_tok = &auth_tok_list_item->auth_tok; if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Considering cadidate auth tok:\n"); ecryptfs_dump_auth_tok(candidate_auth_tok); } /* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */ if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD && !strncmp(candidate_auth_tok->token.password.signature, sig, ECRYPTFS_SIG_SIZE_HEX)) { found_auth_tok = 1; goto leave_list; /* TODO: Transfer the common salt into the * crypt_stat salt */ } } leave_list: if (!found_auth_tok) { ecryptfs_printk(KERN_ERR, "Could not find authentication " "token on temporary list for sig [%.*s]\n", ECRYPTFS_SIG_SIZE_HEX, sig); rc = -EIO; goto out_wipe_list; } else { memcpy(&(candidate_auth_tok->token.password), &(chosen_auth_tok->token.password), sizeof(struct ecryptfs_password)); rc = decrypt_session_key(candidate_auth_tok, crypt_stat); if (rc) { ecryptfs_printk(KERN_ERR, "Error decrypting the " "session key\n"); goto out_wipe_list; } rc = ecryptfs_compute_root_iv(crypt_stat); if (rc) { ecryptfs_printk(KERN_ERR, "Error computing " "the root IV\n"); goto out_wipe_list; } } rc = ecryptfs_init_crypt_ctx(crypt_stat); if (rc) { ecryptfs_printk(KERN_ERR, "Error initializing crypto " "context for cipher [%s]; rc = [%d]\n", crypt_stat->cipher, rc); } out_wipe_list: wipe_auth_tok_list(&auth_tok_list); out: return rc; } /** * write_tag_11_packet * @dest: Target into which Tag 11 packet is to be written * @max: Maximum packet length * @contents: Byte array of contents to copy in * @contents_length: Number of bytes in contents * @packet_length: Length of the Tag 11 packet written; zero on error * * Returns zero on success; non-zero on error. */ static int write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length, size_t *packet_length) { int rc = 0; size_t packet_size_length; (*packet_length) = 0; if ((13 + contents_length) > max) { rc = -EINVAL; ecryptfs_printk(KERN_ERR, "Packet length larger than " "maximum allowable\n"); goto out; } /* General packet header */ /* Packet tag */ dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE; /* Packet length */ rc = write_packet_length(&dest[(*packet_length)], (13 + contents_length), &packet_size_length); if (rc) { ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet " "header; cannot generate packet length\n"); goto out; } (*packet_length) += packet_size_length; /* Tag 11 specific */ /* One-octet field that describes how the data is formatted */ dest[(*packet_length)++] = 0x62; /* binary data */ /* One-octet filename length followed by filename */ dest[(*packet_length)++] = 8; memcpy(&dest[(*packet_length)], "_CONSOLE", 8); (*packet_length) += 8; /* Four-octet number indicating modification date */ memset(&dest[(*packet_length)], 0x00, 4); (*packet_length) += 4; /* Remainder is literal data */ memcpy(&dest[(*packet_length)], contents, contents_length); (*packet_length) += contents_length; out: if (rc) (*packet_length) = 0; return rc; } /** * write_tag_3_packet * @dest: Buffer into which to write the packet * @max: Maximum number of bytes that can be written * @auth_tok: Authentication token * @crypt_stat: The cryptographic context * @key_rec: encrypted key * @packet_size: This function will write the number of bytes that end * up constituting the packet; set to zero on error * * Returns zero on success; non-zero on error. */ static int write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok, struct ecryptfs_crypt_stat *crypt_stat, struct ecryptfs_key_record *key_rec, size_t *packet_size) { size_t i; size_t signature_is_valid = 0; size_t encrypted_session_key_valid = 0; char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES]; struct scatterlist dest_sg[2]; struct scatterlist src_sg[2]; struct mutex *tfm_mutex = NULL; size_t key_rec_size; size_t packet_size_length; size_t cipher_code; struct blkcipher_desc desc = { .tfm = NULL, .flags = CRYPTO_TFM_REQ_MAY_SLEEP }; int rc = 0; (*packet_size) = 0; /* Check for a valid signature on the auth_tok */ for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++) signature_is_valid |= auth_tok->token.password.signature[i]; if (!signature_is_valid) BUG(); ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature, ECRYPTFS_SIG_SIZE); encrypted_session_key_valid = 0; for (i = 0; i < crypt_stat->key_size; i++) encrypted_session_key_valid |= auth_tok->session_key.encrypted_key[i]; if (encrypted_session_key_valid) { memcpy((*key_rec).enc_key, auth_tok->session_key.encrypted_key, auth_tok->session_key.encrypted_key_size); goto encrypted_session_key_set; } if (auth_tok->session_key.encrypted_key_size == 0) auth_tok->session_key.encrypted_key_size = crypt_stat->key_size; if (crypt_stat->key_size == 24 && strcmp("aes", crypt_stat->cipher) == 0) { memset((crypt_stat->key + 24), 0, 8); auth_tok->session_key.encrypted_key_size = 32; } (*key_rec).enc_key_size = auth_tok->session_key.encrypted_key_size; if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags, ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) { ecryptfs_printk(KERN_DEBUG, "Using previously generated " "session key encryption key of size [%d]\n", auth_tok->token.password. session_key_encryption_key_bytes); memcpy(session_key_encryption_key, auth_tok->token.password.session_key_encryption_key, crypt_stat->key_size); ecryptfs_printk(KERN_DEBUG, "Cached session key " "encryption key: \n"); if (ecryptfs_verbosity > 0) ecryptfs_dump_hex(session_key_encryption_key, 16); } if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n"); ecryptfs_dump_hex(session_key_encryption_key, 16); } rc = virt_to_scatterlist(crypt_stat->key, (*key_rec).enc_key_size, src_sg, 2); if (!rc) { ecryptfs_printk(KERN_ERR, "Error generating scatterlist " "for crypt_stat session key\n"); rc = -ENOMEM; goto out; } rc = virt_to_scatterlist((*key_rec).enc_key, (*key_rec).enc_key_size, dest_sg, 2); if (!rc) { ecryptfs_printk(KERN_ERR, "Error generating scatterlist " "for crypt_stat encrypted session key\n"); rc = -ENOMEM; goto out; } if (!strcmp(crypt_stat->cipher, crypt_stat->mount_crypt_stat->global_default_cipher_name) && crypt_stat->mount_crypt_stat->global_key_tfm) { desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm; tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; } else { char *full_alg_name; rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, crypt_stat->cipher, "ecb"); if (rc) goto out; desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC); kfree(full_alg_name); if (IS_ERR(desc.tfm)) { rc = PTR_ERR(desc.tfm); ecryptfs_printk(KERN_ERR, "Could not initialize crypto " "context for cipher [%s]; rc = [%d]\n", crypt_stat->cipher, rc); goto out; } crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY); } if (tfm_mutex) mutex_lock(tfm_mutex); rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key, crypt_stat->key_size); if (rc < 0) { if (tfm_mutex) mutex_unlock(tfm_mutex); ecryptfs_printk(KERN_ERR, "Error setting key for crypto " "context; rc = [%d]\n", rc); goto out; } rc = 0; ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n", crypt_stat->key_size); rc = crypto_blkcipher_encrypt(&desc, dest_sg, src_sg, (*key_rec).enc_key_size); if (rc) { printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc); goto out; } if (tfm_mutex) mutex_unlock(tfm_mutex); ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n"); if (ecryptfs_verbosity > 0) ecryptfs_dump_hex((*key_rec).enc_key, (*key_rec).enc_key_size); encrypted_session_key_set: /* Now we have a valid key_rec. Append it to the * key_rec set. */ key_rec_size = (sizeof(struct ecryptfs_key_record) - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES + ((*key_rec).enc_key_size)); /* TODO: Include a packet size limit as a parameter to this * function once we have multi-packet headers (for versions * later than 0.1 */ if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) { ecryptfs_printk(KERN_ERR, "Keyset too large\n"); rc = -EINVAL; goto out; } /* TODO: Packet size limit */ /* We have 5 bytes of surrounding packet data */ if ((0x05 + ECRYPTFS_SALT_SIZE + (*key_rec).enc_key_size) >= max) { ecryptfs_printk(KERN_ERR, "Authentication token is too " "large\n"); rc = -EINVAL; goto out; } /* This format is inspired by OpenPGP; see RFC 2440 * packet tag 3 */ dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE; /* ver+cipher+s2k+hash+salt+iter+enc_key */ rc = write_packet_length(&dest[(*packet_size)], (0x05 + ECRYPTFS_SALT_SIZE + (*key_rec).enc_key_size), &packet_size_length); if (rc) { ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet " "header; cannot generate packet length\n"); goto out; } (*packet_size) += packet_size_length; dest[(*packet_size)++] = 0x04; /* version 4 */ cipher_code = ecryptfs_code_for_cipher_string(crypt_stat); if (cipher_code == 0) { ecryptfs_printk(KERN_WARNING, "Unable to generate code for " "cipher [%s]\n", crypt_stat->cipher); rc = -EINVAL; goto out; } dest[(*packet_size)++] = cipher_code; dest[(*packet_size)++] = 0x03; /* S2K */ dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */ memcpy(&dest[(*packet_size)], auth_tok->token.password.salt, ECRYPTFS_SALT_SIZE); (*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */ dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */ memcpy(&dest[(*packet_size)], (*key_rec).enc_key, (*key_rec).enc_key_size); (*packet_size) += (*key_rec).enc_key_size; out: if (desc.tfm && !tfm_mutex) crypto_free_blkcipher(desc.tfm); if (rc) (*packet_size) = 0; return rc; } /** * ecryptfs_generate_key_packet_set * @dest: Virtual address from which to write the key record set * @crypt_stat: The cryptographic context from which the * authentication tokens will be retrieved * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat * for the global parameters * @len: The amount written * @max: The maximum amount of data allowed to be written * * Generates a key packet set and writes it to the virtual address * passed in. * * Returns zero on success; non-zero on error. */ int ecryptfs_generate_key_packet_set(char *dest_base, struct ecryptfs_crypt_stat *crypt_stat, struct dentry *ecryptfs_dentry, size_t *len, size_t max) { int rc = 0; struct ecryptfs_auth_tok *auth_tok; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = &ecryptfs_superblock_to_private( ecryptfs_dentry->d_sb)->mount_crypt_stat; size_t written; struct ecryptfs_key_record key_rec; (*len) = 0; if (mount_crypt_stat->global_auth_tok) { auth_tok = mount_crypt_stat->global_auth_tok; if (auth_tok->token_type == ECRYPTFS_PASSWORD) { rc = write_tag_3_packet((dest_base + (*len)), max, auth_tok, crypt_stat, &key_rec, &written); if (rc) { ecryptfs_printk(KERN_WARNING, "Error " "writing tag 3 packet\n"); goto out; } (*len) += written; /* Write auth tok signature packet */ rc = write_tag_11_packet( (dest_base + (*len)), (max - (*len)), key_rec.sig, ECRYPTFS_SIG_SIZE, &written); if (rc) { ecryptfs_printk(KERN_ERR, "Error writing " "auth tok signature packet\n"); goto out; } (*len) += written; } else { ecryptfs_printk(KERN_WARNING, "Unsupported " "authentication token type\n"); rc = -EINVAL; goto out; } if (rc) { ecryptfs_printk(KERN_WARNING, "Error writing " "authentication token packet with sig " "= [%s]\n", mount_crypt_stat->global_auth_tok_sig); rc = -EIO; goto out; } } else BUG(); if (likely((max - (*len)) > 0)) { dest_base[(*len)] = 0x00; } else { ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n"); rc = -EIO; } out: if (rc) (*len) = 0; return rc; }