Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751379AbVKSEXU (ORCPT ); Fri, 18 Nov 2005 23:23:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751375AbVKSEXU (ORCPT ); Fri, 18 Nov 2005 23:23:20 -0500 Received: from c-67-182-200-232.hsd1.ut.comcast.net ([67.182.200.232]:28918 "EHLO sshock.homelinux.net") by vger.kernel.org with ESMTP id S1751358AbVKSEXR (ORCPT ); Fri, 18 Nov 2005 23:23:17 -0500 Date: Fri, 18 Nov 2005 21:23:15 -0700 From: Phillip Hellewell To: akpm@osdl.org Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, viro@ftp.linux.org.uk, mike@halcrow.us, mhalcrow@us.ibm.com, mcthomps@us.ibm.com, yoder1@us.ibm.com Subject: [PATCH 11/12: eCryptfs] Keystore Message-ID: <20051119042315.GK15747@sshock.rn.byu.edu> References: <20051119041130.GA15559@sshock.rn.byu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051119041130.GA15559@sshock.rn.byu.edu> X-URL: http://hellewell.homeip.net/ User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 28834 Lines: 840 eCryptfs keystore. Packet generation and parsing code. Authentication token management code. This file has been trimmed down considerably to support only mount-wide passphrases in the 0.1 release. Signed-off-by: Phillip Hellewell Signed-off-by: Michael Halcrow Signed-off-by: Michael Thompson --- keystore.c | 820 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 820 insertions(+) --- linux-2.6.15-rc1-mm1/fs/ecryptfs/keystore.c 1969-12-31 18:00:00.000000000 -0600 +++ linux-2.6.15-rc1-mm1-ecryptfs/fs/ecryptfs/keystore.c 2005-11-18 11:20:09.000000000 -0600 @@ -0,0 +1,820 @@ +/** + * 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) 2005 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(0, KERN_WARNING, "No key\n"); + rc = -ENOENT; + break; + case EKEYEXPIRED: + ecryptfs_printk(0, KERN_WARNING, "Key expired\n"); + rc = -ETIME; + break; + case EKEYREVOKED: + ecryptfs_printk(0, KERN_WARNING, "Key revoked\n"); + rc = -EINVAL; + break; + default: + ecryptfs_printk(0, KERN_WARNING, "Unknown error code: " + "[%lu]\n", err_code); + rc = -EINVAL; + } + return rc; +} + +static void ecryptfs_dump_auth_tok(struct ecryptfs_auth_tok *auth_tok) +{ + char salt[ECRYPTFS_SALT_SIZE * 2 + 1]; + char sig[ECRYPTFS_SIG_SIZE_HEX + 1]; + ecryptfs_printk(1, KERN_NOTICE, "Auth tok at mem loc [%p]:\n", + auth_tok); + ecryptfs_printk(1, KERN_NOTICE, " * instanceof = [%d]\n", + auth_tok->instanceof); + ecryptfs_printk(1, KERN_NOTICE, " * instantiated = [%d]\n", + auth_tok->instantiated); + switch (auth_tok->instanceof) { + case ECRYPTFS_PASSWORD: + ecryptfs_printk(1, KERN_NOTICE, " * password = [%s]\n", + auth_tok->token.password.password); + ecryptfs_printk(1, KERN_NOTICE, " * password_size = [%d]\n", + auth_tok->token.password.password_size); + ecryptfs_to_hex(salt, auth_tok->token.password.salt, + ECRYPTFS_SALT_SIZE); + salt[ECRYPTFS_SALT_SIZE * 2] = '\0'; + ecryptfs_printk(1, KERN_NOTICE, " * salt = [%s]\n", salt); + ecryptfs_printk(1, KERN_NOTICE, " * saltless = [%d]\n", + auth_tok->token.password.saltless); + memcpy(sig, auth_tok->token.password.signature, + ECRYPTFS_SIG_SIZE_HEX); + sig[ECRYPTFS_SIG_SIZE_HEX] = '\0'; + ecryptfs_printk(1, KERN_NOTICE, " * signature = [%s]\n", sig); + break; + case ECRYPTFS_PRIVATE_KEY: + ecryptfs_printk(1, KERN_NOTICE, " * (NO PRIVATE KEY SUPPORT " + "IN ECRYPTFS VERSION 0.1)\n"); + break; + default: + ecryptfs_printk(1, KERN_NOTICE, " * Unrecognized instanceof\n"); + } + ecryptfs_printk(1, KERN_NOTICE, " * session_key.flags = [0x%x]\n", + auth_tok->session_key.flags); + if (auth_tok->session_key.flags + & ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT) + ecryptfs_printk(1, KERN_NOTICE, + " * Userspace decrypt request set\n"); + if (auth_tok->session_key.flags + & ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT) + ecryptfs_printk(1, KERN_NOTICE, + " * Userspace encrypt request set\n"); + if (auth_tok->session_key.flags & ECRYPTFS_CONTAINS_DECRYPTED_KEY) { + ecryptfs_printk(1, KERN_NOTICE, " * Contains decrypted key\n"); + ecryptfs_printk(1, KERN_NOTICE, + " * session_key.decrypted_key_size = [0x%x]\n", + auth_tok->session_key.decrypted_key_size); + ecryptfs_printk(1, KERN_NOTICE, " * Decrypted session key " + "dump:\n"); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(auth_tok->session_key.decrypted_key, + ECRYPTFS_DEFAULT_KEY_BYTES); + } + if (auth_tok->session_key.flags & ECRYPTFS_CONTAINS_ENCRYPTED_KEY) { + ecryptfs_printk(1, KERN_NOTICE, " * Contains encrypted key\n"); + ecryptfs_printk(1, KERN_NOTICE, + " * session_key.encrypted_key_size = [0x%x]\n", + auth_tok->session_key.encrypted_key_size); + ecryptfs_printk(1, KERN_NOTICE, " * Encrypted session key " + "dump:\n"); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(auth_tok->session_key.encrypted_key, + auth_tok->session_key. + encrypted_key_size); + } +} + +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; + + ecryptfs_printk(1, KERN_NOTICE, "Enter\n"); + 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; + kmem_cache_free(ecryptfs_auth_tok_list_item_cache, + auth_tok_list_item); + } + ecryptfs_printk(1, KERN_NOTICE, "Exit\n"); +} + +kmem_cache_t *ecryptfs_auth_tok_list_item_cache; + +/** + * @return Zero on success + */ +static int parse_packet_length(unsigned char *data, int *offset, int *size) +{ + int rc = 0; + + if (data[(*offset)] < 192) { + /* One-byte length */ + (*size) = data[(*offset)++]; + } else if (data[(*offset)] < 224) { + /* Two-byte length */ + (*size) = ((data[(*offset)++] - 192) * 256); + (*size) += (data[(*offset)++] + 192); + } else if (data[(*offset)] == 255) { + /* Three-byte length; we're not supposed to see this */ + ecryptfs_printk(0, KERN_ERR, "Three-byte packet length not " + "supported\n"); + rc = -EINVAL; + goto out; + } else { + ecryptfs_printk(0, KERN_ERR, "Error parsing packet length\n"); + rc = -EINVAL; + goto out; + } +out: + return rc; +} + +static int write_packet_length(char *dest, int *dest_offset, int size) +{ + int rc = 0; + + if (size < 192) { + dest[(*dest_offset)] = size; + (*dest_offset)++; + } else if (size < 65536) { + dest[(*dest_offset)] = (((size - 192) / 256) + 192); + (*dest_offset)++; + dest[(*dest_offset)] = ((size - 192) % 256); + (*dest_offset)++; + } else { + rc = -EINVAL; + ecryptfs_printk(0, KERN_WARNING, + "Unsupported packet size: [%d]\n", size); + } + return rc; +} + +/** + * Passphrase packet. + * + * @return New offset in the packet set page; error value on error. + */ +static int +parse_tag_3_packet(struct ecryptfs_crypt_stats *crypt_stats, + unsigned char *data, struct list_head *auth_tok_list) +{ + int i = 0; + int rc = 0; + int body_size = 0; + struct ecryptfs_auth_tok *auth_tok; + struct ecryptfs_auth_tok_list_item *auth_tok_list_item; + + ecryptfs_printk(1, KERN_NOTICE, "Enter\n"); + if (data[i++] != 0x8c) { + ecryptfs_printk(0, KERN_ERR, "Enter w/ first byte != 0x8c\n"); + rc = -EINVAL; + goto out_no_mem; + } + /* 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, + SLAB_KERNEL); + if (!auth_tok_list_item) { + ecryptfs_printk(0, KERN_ERR, "Unable to allocate memory\n"); + rc = -ENOMEM; + goto out_no_mem; + } + auth_tok = &auth_tok_list_item->auth_tok; + memset(auth_tok, 0, sizeof(struct ecryptfs_auth_tok)); + /* TODO: Make *sure* it's encrypted; do this w/ policy tokens. + * Actually, this is probably not the right place to set this + * flag. If the eCryptfs marker matches, then we probably have + * a real tag 3 packet, and hence the file is most likely + * encrypted. */ + rc = parse_packet_length(data, &i, &body_size); + if (rc) + goto out; + auth_tok->session_key.encrypted_key_size = + body_size - (0x05 + ECRYPTFS_SALT_SIZE); + ecryptfs_printk(1, KERN_NOTICE, "Encrypted key size = [%d]\n", + auth_tok->session_key.encrypted_key_size); + if (data[i++] != 0x04) { + ecryptfs_printk(1, KERN_NOTICE, "Unknown version number " + "[%d]\n", data[i - 1]); + rc = -EINVAL; + goto out; + } + ecryptfs_cipher_code_to_string(crypt_stats->cipher, (u16)data[i]); + switch(data[i++]) { + case 0x07: + crypt_stats->key_size_bits = 128; + break; + case 0x08: + crypt_stats->key_size_bits = 192; + break; + case 0x09: + crypt_stats->key_size_bits = 256; + break; + } + ecryptfs_init_crypt_ctx(crypt_stats); + if (data[i++] != 0x03) { + ecryptfs_printk(0, KERN_ERR, "Only S2K ID 3 is currently " + "supported\n"); + rc = -ENOSYS; + goto out; + } + /* TODO: finish the hash mapping */ + switch (data[i++]) { + case 0x01: + /* Choose MD5 */ + memcpy(auth_tok->token.password.salt, &data[i], + ECRYPTFS_SALT_SIZE); + i += ECRYPTFS_SALT_SIZE; + auth_tok->token.password.hash_iterations = + ((u32) 16 + (data[i] & 15)) << ((data[i] >> 4) + 6); + i++; + memcpy(auth_tok->session_key.encrypted_key, &data[i], + auth_tok->session_key.encrypted_key_size); + i += auth_tok->session_key.encrypted_key_size; + auth_tok->session_key.flags &= ~ECRYPTFS_CONTAINS_DECRYPTED_KEY; + auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_ENCRYPTED_KEY; + auth_tok->token.password.hash_algo = 0x01; + break; + default: + ecryptfs_printk(0, KERN_ERR, "Unsupported hash algorithm: " + "[%d]\n", data[i - 1]); + rc = -ENOSYS; + goto out; + } + /* TODO: Use the keyring */ + auth_tok->uid = current->uid; + auth_tok->instanceof = ECRYPTFS_PASSWORD; + if (data[i++] != 0xed) { + ecryptfs_printk(0, KERN_ERR, "No (ecryptfs-specific) literal " + "packet containing authentication token " + "signature found after tag 3 packet\n"); + rc = -EINVAL; + goto out; + } + if (data[i++] != (ECRYPTFS_SIG_SIZE + 13)) { + ecryptfs_printk(0, KERN_ERR, "Unrecognizable packet\n"); + rc = -EINVAL; + goto out; + } + if (data[i++] != 0x62) { + ecryptfs_printk(0, KERN_ERR, "Unrecognizable packet\n"); + rc = -EINVAL; + goto out; + } + if (data[i++] != 0x08) { + ecryptfs_printk(0, KERN_ERR, "Unrecognizable packet\n"); + rc = -EINVAL; + goto out; + } + i += 12; /* We don't care about the filename or the timestamp */ + /* TODO: Parametarize; we might actually want userspace to + * decrypt the session key. */ + auth_tok->session_key.flags &= + ~ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT; + auth_tok->session_key.flags &= + ~ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT; + ecryptfs_to_hex(auth_tok->token.password.signature, &data[i], + ECRYPTFS_SIG_SIZE); + auth_tok->token.password.signature[ECRYPTFS_PASSWORD_SIG_SIZE] = '\0'; + rc = i; + list_add(&auth_tok_list_item->list, auth_tok_list); + crypt_stats->encrypted = 1; + goto out_success; +out: + kmem_cache_free(ecryptfs_auth_tok_list_item_cache, + auth_tok_list_item); +out_no_mem: +out_success: + ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc); + return rc; +} + +/** + * Decrypt the session key with the given auth_tok. + * + * TODO: Performance: This is a good candidate for optimization. + * + * @param auth_tok + * @return 0 on success; non-zero error otherwise + */ +static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok, + struct ecryptfs_crypt_stats *crypt_stats) +{ + int rc = 0; + struct ecryptfs_password *password_s_ptr; + struct crypto_tfm *tfm = NULL; + struct scatterlist src_sg[2], dst_sg[2]; + /* TODO: Use virt_to_scatterlist for these */ + char *encrypted_session_key; + char *session_key; + + password_s_ptr = &auth_tok->token.password; + if (password_s_ptr->session_key_encryption_key_set) + ecryptfs_printk(1, KERN_NOTICE, "Session key encryption key " + "set; skipping key generation\n"); + ecryptfs_printk(1, KERN_NOTICE, "Session key encryption key (size [%d])" + ":\n", password_s_ptr->session_key_encryption_key_size); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key, + password_s_ptr-> + session_key_encryption_key_size); + tfm = crypto_alloc_tfm(crypt_stats->cipher, 0); + if (!tfm) { + ecryptfs_printk(0, KERN_ERR, "Error allocating crypto " + "context\n"); + rc = -ENOMEM; + goto out; + } + crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key, + password_s_ptr->session_key_encryption_key_size); + /* TODO: virt_to_scatterlist */ + encrypted_session_key = (char *)__get_free_page(GFP_KERNEL); + if (!encrypted_session_key) { + ecryptfs_printk(0, KERN_ERR, "Out of memory\n"); + rc = -ENOMEM; + goto out; + } + session_key = (char *)__get_free_page(GFP_KERNEL); + if (!session_key) { + kfree(encrypted_session_key); + ecryptfs_printk(0, KERN_ERR, "Out of memory\n"); + rc = -ENOMEM; + goto out; + } + 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; + /* TODO: 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; + /* TODO: Handle error condition */ + crypto_cipher_decrypt(tfm, dst_sg, src_sg, + auth_tok->session_key.encrypted_key_size); + 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_stats->key, auth_tok->session_key.decrypted_key, + auth_tok->session_key.decrypted_key_size); + crypt_stats->key_valid = 1; + crypt_stats->key_size_bits = + auth_tok->session_key.decrypted_key_size * 8; + ecryptfs_printk(1, KERN_NOTICE, "Decrypted session key:\n"); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(crypt_stats->key, + crypt_stats->key_size_bits / 8); + free_page((unsigned long)encrypted_session_key); + free_page((unsigned long)session_key); +out: + if (tfm) + crypto_free_tfm(tfm); + return rc; +} + +/** + * N.B. This comment is applicable to 0.2 release (and later) only. + * Extract the authentication token signatures. eCryptfs expects this + * function to recover the symmetric key of the crypt_stats structure + * if at all possible, given the current packet set. Authentication + * tokens are composed of the tokens themselves and their descriptors. + * It is possible to have an authentication token object in the + * keyring that only has a descriptor and not a token component. Each + * eCryptfs file header contains a concatenation of descriptors. For + * each descriptor, this function assures that an authentication token + * object is instantiated in the keyring. This instantiation takes + * place in the request_key callout application. Thus, the callout + * application requires the complete descriptor. The crypt_stats + * object contains a set of descriptors that apply to this file. When + * the headers are written out, they are re-constructed from the set + * of authentication token descriptors. + * + * If at any point we have a problem parsing the packets, we will -EIO and + * just bail out. + * + * GOAL: Get crypt_stats to have the file's session key. + * + * @param dest The header page in memory + * @param version Version of file format, to guide parsing behavior + * @return 0 if a valid authentication token was retrieved and processed; + * negative value for file not encrypted or for error conditions + */ +int ecryptfs_parse_packet_set(unsigned char *dest, + struct ecryptfs_crypt_stats *crypt_stats, + struct dentry *ecryptfs_dentry, int version) +{ + int i = 0; + int rc = 0; + int found_auth_tok = 0; + int 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_stats *mount_crypt_stats = + &(ECRYPTFS_SUPERBLOCK_TO_PRIVATE( + ecryptfs_dentry->d_sb)->mount_crypt_stats); + struct ecryptfs_auth_tok *candidate_auth_tok = NULL; + + ecryptfs_printk(1, KERN_NOTICE, "Enter\n"); + ecryptfs_set_default_sizes(crypt_stats); + 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) + switch (dest[i]) { + case 0x8c: /* tag 3 packet; s2k */ + rc = parse_tag_3_packet(crypt_stats, + (unsigned char *)&dest[i], + &auth_tok_list); + if (rc != -EINVAL && rc != -ENOMEM) { + i += rc; + rc = 0; + } else { + ecryptfs_printk(0, KERN_ERR, "Error parsing " + "tag 3 packet\n"); + rc = -EIO; + goto out_wipe_list; + } + break; + default: + ecryptfs_printk(1, KERN_NOTICE, "No packet at offset " + "[%d] of the file header; hex value of " + "character is [0x%.2x]\n", i, dest[i]); + next_packet_is_auth_tok_packet = 0; + } + if (list_empty(&auth_tok_list)) { + rc = -EINVAL; /* Do not support non-encrypted files */ + goto out; + } + + /* If we have a global auth tok, then use it should be tried */ + if (mount_crypt_stats->global_auth_tok) { + memcpy(sig, mount_crypt_stats->global_auth_tok_sig, + ECRYPTFS_SIG_SIZE_HEX); + chosen_auth_tok = mount_crypt_stats->global_auth_tok; + } else + BUG(); /* This should not be the case in 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(1, KERN_NOTICE, + "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->instanceof == 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_stats salt */ + } + } +leave_list: + if (!found_auth_tok) { + ecryptfs_printk(0, KERN_ERR, "Could not find authentication " + "token on temporary list for sig [%.*s]\n", + ECRYPTFS_SIG_SIZE_HEX, sig); + goto out_wipe_list; + } else { + memcpy(&(candidate_auth_tok->token.password), + &(chosen_auth_tok->token.password), + sizeof(struct ecryptfs_password)); + decrypt_session_key(candidate_auth_tok, crypt_stats); + } + +out_wipe_list: + wipe_auth_tok_list(&auth_tok_list); +out: + ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc); + return rc; +} + +/** + * Write passphrase packet + * + * @param dest Buffer into which to write the packet + * @param max Maximum number of bytes that can be writtn + * @return Number of bytes written; 0 on error + */ +static int +write_tag_3_packet(char *dest, int dest_offset, int max, + struct ecryptfs_auth_tok *auth_tok, + struct ecryptfs_crypt_stats *crypt_stats) +{ + int rc = 0; + struct ecryptfs_key_record key_rec; + int i; + int signature_is_valid = 0; + int 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 crypto_tfm *tfm = NULL; + int key_rec_size; + int offset_save = 0; + + ecryptfs_printk(1, KERN_NOTICE, "Enter; dest_offset = [%d]\n", + dest_offset); + /* 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); + key_rec.enc_key_size_bits = crypt_stats->key_size_bits; + key_rec.type = ECRYPTFS_PACKET_SET_TYPE_PASSWORD; + + encrypted_session_key_valid = 0; + if (auth_tok->session_key.encrypted_key_size == 0) + auth_tok->session_key.encrypted_key_size = + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES; + for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++) + encrypted_session_key_valid |= + auth_tok->session_key.encrypted_key[i]; + if (auth_tok->session_key.encrypted_key_size == 0) { + ecryptfs_printk(0, KERN_WARNING, "auth_tok->session_key." + "encrypted_key_size == 0"); + auth_tok->session_key.encrypted_key_size = + ECRYPTFS_DEFAULT_KEY_BYTES; + } + 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->token.password.session_key_encryption_key_set) { + ecryptfs_printk(1, KERN_NOTICE, "Using previously generated " + "session key encryption key of size [%d]\n", + auth_tok->token.password. + session_key_encryption_key_size); + memcpy(session_key_encryption_key, + auth_tok->token.password.session_key_encryption_key, + auth_tok->token.password. + session_key_encryption_key_size); + ecryptfs_printk(1, KERN_NOTICE, + "Cached session key " "encryption key: \n"); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(session_key_encryption_key, 16); + goto session_key_encryption_key_set; + } + session_key_encryption_key_set: + if (unlikely(ecryptfs_verbosity > 0)) { + ecryptfs_printk(1, KERN_NOTICE, "Session key encryption key:" + "\n"); + ecryptfs_dump_hex(session_key_encryption_key, 16); + } + /* Encrypt the key with the key encryption key */ + /* Set up the scatterlists */ + rc = virt_to_scatterlist(crypt_stats->key, + crypt_stats->key_size_bits / 8, src_sg, 2); + if (!rc) { + ecryptfs_printk(0, KERN_ERR, "Error generating scatterlist " + "for crypt_stats session key\n"); + rc = -ENOMEM; + goto out; + } + rc = virt_to_scatterlist(key_rec.enc_key, + key_rec.enc_key_size_bits / 8, dest_sg, 2); + if (!rc) { + ecryptfs_printk(0, KERN_ERR, "Error generating scatterlist " + "for crypt_stats encrypted session key\n"); + rc = -ENOMEM; + goto out; + } + /* Initialize the key encryption context */ + ASSERT(crypt_stats->cipher); + if ((tfm = crypto_alloc_tfm(crypt_stats->cipher, 0)) == NULL) { + ecryptfs_printk(0, KERN_ERR, "Could not initialize crypto " + "context for cipher [%s]\n", + crypt_stats->cipher); + rc = 0; + goto out; + } + /* Set the key encryption key */ + rc = crypto_cipher_setkey(tfm, session_key_encryption_key, + ECRYPTFS_DEFAULT_KEY_BYTES); + if (rc < 0) { + ecryptfs_printk(0, KERN_ERR, "Error setting key for crypto " + "context\n"); + rc = 0; + goto out; + } + ecryptfs_printk(1, KERN_NOTICE, "Encrypting [%d] bytes of the key\n", + crypt_stats->key_size_bits / 8); + crypto_cipher_encrypt(tfm, dest_sg, src_sg, + crypt_stats->key_size_bits / 8); + + ecryptfs_printk(1, KERN_NOTICE, "This should be the encrypted key:\n"); + if (ecryptfs_verbosity > 0) + ecryptfs_dump_hex(key_rec.enc_key, + key_rec.enc_key_size_bits / 8); +encrypted_session_key_set: + /* Now we have a valid key_rec. Append it to the + * key_rec set. */ + key_rec_size = KEY_REC_SIZE(key_rec); + if ((dest_offset + key_rec_size) >= ECRYPTFS_MAX_KEYSET_SIZE) { + ecryptfs_printk(0, KERN_ERR, "Keyset too large\n"); + rc = 0; + goto out; + } + offset_save = dest_offset; + if ((dest_offset + 0x05 + ECRYPTFS_SALT_SIZE + + (key_rec.enc_key_size_bits / 8)) >= PAGE_CACHE_SIZE) { + ecryptfs_printk(0, KERN_ERR, "Too many authentication tokens; " + "cryptfs does not yet support this many\n"); + rc = 0; + goto out; + } + /* This format is inspired by OpenPGP; see RFC 2440 + * packet tag 3 */ + *(dest + (dest_offset++)) = 0x8c; /* tag 3 */ + /* ver+cipher+s2k+hash+salt+iter+enc_key */ + rc = write_packet_length(dest, &dest_offset, + (0x05 + ECRYPTFS_SALT_SIZE + + (key_rec.enc_key_size_bits / 8))); + *(dest + (dest_offset++)) = 0x04; /* version 4 */ + + rc = ecryptfs_code_for_cipher_string(crypt_stats->cipher); + if (rc == 0) { + ecryptfs_printk(0, KERN_WARNING, "Unable to generate code for " + "cipher [%s]\n", crypt_stats->cipher); + goto out; + } + if (rc == 0x07) { + switch (crypt_stats->key_size_bits) { + case 128: + break; + case 192: + rc = 0x08; /* AES-192 */ + break; + case 256: + rc = 0x09; /* AES-256 */ + break; + default: + rc = -EINVAL; + ecryptfs_printk(0, KERN_WARNING, "Unsupported AES key " + "size: [%d]\n", + crypt_stats->key_size_bits); + goto out; + } + } + *(dest + (dest_offset++)) = rc; + rc = 0; + *(dest + (dest_offset++)) = 0x03; /* S2K */ + *(dest + (dest_offset++)) = 0x01; /* MD5 (TODO) */ + memcpy((dest + dest_offset), auth_tok->token.password.salt, + ECRYPTFS_SALT_SIZE); + dest_offset += ECRYPTFS_SALT_SIZE; /* salt */ + *(dest + (dest_offset++)) = 0x60; /* hash iterations */ + memcpy((dest + dest_offset), key_rec.enc_key, + key_rec.enc_key_size_bits / 8); + dest_offset += (key_rec.enc_key_size_bits / 8); + /* Write auth tok signature packet */ + *(dest + (dest_offset++)) = 0xed; /* tag 11 */ + *(dest + (dest_offset++)) = ECRYPTFS_SIG_SIZE + 13; /* packet + * length */ + *(dest + (dest_offset++)) = 0x62; /* binary type */ + *(dest + (dest_offset++)) = 0x08; /* filename length */ + strncpy((dest + dest_offset), "_CONSOLE", 0x08); + dest_offset += 0x08; + memset((dest + dest_offset), 0, 4); + dest_offset += 4; + memcpy((dest + dest_offset), key_rec.sig, ECRYPTFS_SIG_SIZE); + dest_offset += ECRYPTFS_SIG_SIZE; + *(dest + (dest_offset)) = 0x00; /* NULL terminator */ + rc = dest_offset; +out: + if (tfm) + crypto_free_tfm(tfm); + ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc); + return rc; +} + +/** + * Generates a key packet set and writes it to the virtual address + * passed in. + * + * @param dest Page to which to write the key record set + * @param crypt_stats The cryptographic context from which the authentication + * tokens will be retrieved + * @param len The amount written + * @return Zero on success + */ +int +ecryptfs_generate_key_packet_set(char *dest_base, + struct ecryptfs_crypt_stats *crypt_stats, + struct dentry *ecryptfs_dentry, int *len) +{ + int rc = 0; + struct ecryptfs_auth_tok *auth_tok; + int dest_offset = 0; + struct ecryptfs_mount_crypt_stats *mount_crypt_stats = + &(ECRYPTFS_SUPERBLOCK_TO_PRIVATE( + ecryptfs_dentry->d_sb)->mount_crypt_stats); + int written; + + ecryptfs_printk(1, KERN_NOTICE, "Enter\n"); + (*len) = 0; + if (mount_crypt_stats->global_auth_tok) { + auth_tok = mount_crypt_stats->global_auth_tok; + switch (auth_tok->instanceof) { + case ECRYPTFS_PASSWORD: + written = write_tag_3_packet(dest_base, dest_offset, + PAGE_CACHE_SIZE, auth_tok, + crypt_stats); + break; + default: + ecryptfs_printk(0, KERN_WARNING, "Unknown " + "authentication token type [%d]\n", + auth_tok->instanceof); + rc = -EINVAL; + goto out; + } + if (written == 0) { + ecryptfs_printk(1, KERN_WARNING, "Error writing " + "authentication token packet with sig " + "= [%s]\n", + mount_crypt_stats->global_auth_tok_sig); + rc = -EIO; + goto out; + } else { + dest_offset += written; + (*len) += written; + } + } else + BUG(); + out: + ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc); + return rc; +} - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/