diff options
Diffstat (limited to 'fs/ecryptfs/keystore.c')
| -rw-r--r-- | fs/ecryptfs/keystore.c | 1061 |
1 files changed, 1061 insertions, 0 deletions
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c new file mode 100644 index 0000000000000..ba454785a0c58 --- /dev/null +++ b/fs/ecryptfs/keystore.c @@ -0,0 +1,1061 @@ +/** + * 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 <mhalcrow@us.ibm.com> + * Michael C. Thompson <mcthomps@us.ibm.com> + * + * 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 <linux/string.h> +#include <linux/sched.h> +#include <linux/syscalls.h> +#include <linux/pagemap.h> +#include <linux/key.h> +#include <linux/random.h> +#include <linux/crypto.h> +#include <linux/scatterlist.h> +#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, SLAB_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) +{ + int rc = 0; + struct ecryptfs_password *password_s_ptr; + struct crypto_tfm *tfm = NULL; + 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; + + 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) { + tfm = crypt_stat->mount_crypt_stat->global_key_tfm; + tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; + } else { + tfm = crypto_alloc_tfm(crypt_stat->cipher, + CRYPTO_TFM_REQ_WEAK_KEY); + if (!tfm) { + printk(KERN_ERR "Error allocating crypto context\n"); + rc = -ENOMEM; + goto out; + } + } + if (password_s_ptr->session_key_encryption_key_bytes + < crypto_tfm_alg_min_keysize(tfm)) { + printk(KERN_WARNING "Session key encryption key is [%d] bytes; " + "minimum keysize for selected cipher is [%d] bytes.\n", + password_s_ptr->session_key_encryption_key_bytes, + crypto_tfm_alg_min_keysize(tfm)); + rc = -EINVAL; + goto out; + } + if (tfm_mutex) + mutex_lock(tfm_mutex); + crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key, + crypt_stat->key_size); + /* 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; + /* 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_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); + 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_tfm(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) +{ + int rc = 0; + + 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 crypto_tfm *tfm = NULL; + struct mutex *tfm_mutex = NULL; + size_t key_rec_size; + size_t packet_size_length; + size_t cipher_code; + + (*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) { + tfm = crypt_stat->mount_crypt_stat->global_key_tfm; + tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex; + } else + tfm = crypto_alloc_tfm(crypt_stat->cipher, 0); + if (!tfm) { + ecryptfs_printk(KERN_ERR, "Could not initialize crypto " + "context for cipher [%s]\n", + crypt_stat->cipher); + rc = -EINVAL; + goto out; + } + if (tfm_mutex) + mutex_lock(tfm_mutex); + rc = crypto_cipher_setkey(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\n"); + goto out; + } + rc = 0; + ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n", + crypt_stat->key_size); + crypto_cipher_encrypt(tfm, dest_sg, src_sg, + (*key_rec).enc_key_size); + 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 (tfm && !tfm_mutex) + crypto_free_tfm(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; +} |