/** * eCryptfs: Linux filesystem encryption layer * * Copyright (C) 1997-2004 Erez Zadok * Copyright (C) 2001-2004 Stony Brook University * Copyright (C) 2004-2007 International Business Machines Corp. * Author(s): Michael A. Halcrow <mahalcro@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/fs.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/random.h> #include <linux/compiler.h> #include <linux/key.h> #include <linux/namei.h> #include <linux/crypto.h> #include <linux/file.h> #include <linux/scatterlist.h> #include "ecryptfs_kernel.h" static int ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, struct page *dst_page, int dst_offset, struct page *src_page, int src_offset, int size, unsigned char *iv); static int ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, struct page *dst_page, int dst_offset, struct page *src_page, int src_offset, int size, unsigned char *iv); /** * ecryptfs_to_hex * @dst: Buffer to take hex character representation of contents of * src; must be at least of size (src_size * 2) * @src: Buffer to be converted to a hex string respresentation * @src_size: number of bytes to convert */ void ecryptfs_to_hex(char *dst, char *src, size_t src_size) { int x; for (x = 0; x < src_size; x++) sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]); } /** * ecryptfs_from_hex * @dst: Buffer to take the bytes from src hex; must be at least of * size (src_size / 2) * @src: Buffer to be converted from a hex string respresentation to raw value * @dst_size: size of dst buffer, or number of hex characters pairs to convert */ void ecryptfs_from_hex(char *dst, char *src, int dst_size) { int x; char tmp[3] = { 0, }; for (x = 0; x < dst_size; x++) { tmp[0] = src[x * 2]; tmp[1] = src[x * 2 + 1]; dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16); } } /** * ecryptfs_calculate_md5 - calculates the md5 of @src * @dst: Pointer to 16 bytes of allocated memory * @crypt_stat: Pointer to crypt_stat struct for the current inode * @src: Data to be md5'd * @len: Length of @src * * Uses the allocated crypto context that crypt_stat references to * generate the MD5 sum of the contents of src. */ static int ecryptfs_calculate_md5(char *dst, struct ecryptfs_crypt_stat *crypt_stat, char *src, int len) { struct scatterlist sg; struct hash_desc desc = { .tfm = crypt_stat->hash_tfm, .flags = CRYPTO_TFM_REQ_MAY_SLEEP }; int rc = 0; mutex_lock(&crypt_stat->cs_hash_tfm_mutex); sg_init_one(&sg, (u8 *)src, len); if (!desc.tfm) { desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0, CRYPTO_ALG_ASYNC); if (IS_ERR(desc.tfm)) { rc = PTR_ERR(desc.tfm); ecryptfs_printk(KERN_ERR, "Error attempting to " "allocate crypto context; rc = [%d]\n", rc); goto out; } crypt_stat->hash_tfm = desc.tfm; } crypto_hash_init(&desc); crypto_hash_update(&desc, &sg, len); crypto_hash_final(&desc, dst); mutex_unlock(&crypt_stat->cs_hash_tfm_mutex); out: return rc; } int ecryptfs_crypto_api_algify_cipher_name(char **algified_name, char *cipher_name, char *chaining_modifier) { int cipher_name_len = strlen(cipher_name); int chaining_modifier_len = strlen(chaining_modifier); int algified_name_len; int rc; algified_name_len = (chaining_modifier_len + cipher_name_len + 3); (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL); if (!(*algified_name)) { rc = -ENOMEM; goto out; } snprintf((*algified_name), algified_name_len, "%s(%s)", chaining_modifier, cipher_name); rc = 0; out: return rc; } /** * ecryptfs_derive_iv * @iv: destination for the derived iv vale * @crypt_stat: Pointer to crypt_stat struct for the current inode * @offset: Offset of the page whose's iv we are to derive * * Generate the initialization vector from the given root IV and page * offset. * * Returns zero on success; non-zero on error. */ static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat, pgoff_t offset) { int rc = 0; char dst[MD5_DIGEST_SIZE]; char src[ECRYPTFS_MAX_IV_BYTES + 16]; if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "root iv:\n"); ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes); } /* TODO: It is probably secure to just cast the least * significant bits of the root IV into an unsigned long and * add the offset to that rather than go through all this * hashing business. -Halcrow */ memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes); memset((src + crypt_stat->iv_bytes), 0, 16); snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset); if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "source:\n"); ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16)); } rc = ecryptfs_calculate_md5(dst, crypt_stat, src, (crypt_stat->iv_bytes + 16)); if (rc) { ecryptfs_printk(KERN_WARNING, "Error attempting to compute " "MD5 while generating IV for a page\n"); goto out; } memcpy(iv, dst, crypt_stat->iv_bytes); if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "derived iv:\n"); ecryptfs_dump_hex(iv, crypt_stat->iv_bytes); } out: return rc; } /** * ecryptfs_init_crypt_stat * @crypt_stat: Pointer to the crypt_stat struct to initialize. * * Initialize the crypt_stat structure. */ void ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) { memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); mutex_init(&crypt_stat->cs_mutex); mutex_init(&crypt_stat->cs_tfm_mutex); mutex_init(&crypt_stat->cs_hash_tfm_mutex); crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED; } /** * ecryptfs_destruct_crypt_stat * @crypt_stat: Pointer to the crypt_stat struct to initialize. * * Releases all memory associated with a crypt_stat struct. */ void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat) { if (crypt_stat->tfm) crypto_free_blkcipher(crypt_stat->tfm); if (crypt_stat->hash_tfm) crypto_free_hash(crypt_stat->hash_tfm); memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat)); } void ecryptfs_destruct_mount_crypt_stat( struct ecryptfs_mount_crypt_stat *mount_crypt_stat) { if (mount_crypt_stat->global_auth_tok_key) key_put(mount_crypt_stat->global_auth_tok_key); if (mount_crypt_stat->global_key_tfm) crypto_free_blkcipher(mount_crypt_stat->global_key_tfm); memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat)); } /** * virt_to_scatterlist * @addr: Virtual address * @size: Size of data; should be an even multiple of the block size * @sg: Pointer to scatterlist array; set to NULL to obtain only * the number of scatterlist structs required in array * @sg_size: Max array size * * Fills in a scatterlist array with page references for a passed * virtual address. * * Returns the number of scatterlist structs in array used */ int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg, int sg_size) { int i = 0; struct page *pg; int offset; int remainder_of_page; while (size > 0 && i < sg_size) { pg = virt_to_page(addr); offset = offset_in_page(addr); if (sg) { sg[i].page = pg; sg[i].offset = offset; } remainder_of_page = PAGE_CACHE_SIZE - offset; if (size >= remainder_of_page) { if (sg) sg[i].length = remainder_of_page; addr += remainder_of_page; size -= remainder_of_page; } else { if (sg) sg[i].length = size; addr += size; size = 0; } i++; } if (size > 0) return -ENOMEM; return i; } /** * encrypt_scatterlist * @crypt_stat: Pointer to the crypt_stat struct to initialize. * @dest_sg: Destination of encrypted data * @src_sg: Data to be encrypted * @size: Length of data to be encrypted * @iv: iv to use during encryption * * Returns the number of bytes encrypted; negative value on error */ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, struct scatterlist *dest_sg, struct scatterlist *src_sg, int size, unsigned char *iv) { struct blkcipher_desc desc = { .tfm = crypt_stat->tfm, .info = iv, .flags = CRYPTO_TFM_REQ_MAY_SLEEP }; int rc = 0; BUG_ON(!crypt_stat || !crypt_stat->tfm || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)); if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n", crypt_stat->key_size); ecryptfs_dump_hex(crypt_stat->key, crypt_stat->key_size); } /* Consider doing this once, when the file is opened */ mutex_lock(&crypt_stat->cs_tfm_mutex); rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key, crypt_stat->key_size); if (rc) { ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", rc); mutex_unlock(&crypt_stat->cs_tfm_mutex); rc = -EINVAL; goto out; } ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size); crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size); mutex_unlock(&crypt_stat->cs_tfm_mutex); out: return rc; } static void ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx, int *byte_offset, struct ecryptfs_crypt_stat *crypt_stat, unsigned long extent_num) { unsigned long lower_extent_num; int extents_occupied_by_headers_at_front; int bytes_occupied_by_headers_at_front; int extent_offset; int extents_per_page; bytes_occupied_by_headers_at_front = ( crypt_stat->header_extent_size * crypt_stat->num_header_extents_at_front ); extents_occupied_by_headers_at_front = ( bytes_occupied_by_headers_at_front / crypt_stat->extent_size ); lower_extent_num = extents_occupied_by_headers_at_front + extent_num; extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; (*lower_page_idx) = lower_extent_num / extents_per_page; extent_offset = lower_extent_num % extents_per_page; (*byte_offset) = extent_offset * crypt_stat->extent_size; ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = " "[%d]\n", crypt_stat->header_extent_size); ecryptfs_printk(KERN_DEBUG, " * crypt_stat->" "num_header_extents_at_front = [%d]\n", crypt_stat->num_header_extents_at_front); ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_" "front = [%d]\n", extents_occupied_by_headers_at_front); ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n", lower_extent_num); ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n", extents_per_page); ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n", (*lower_page_idx)); ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n", extent_offset); ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n", (*byte_offset)); } static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx, struct page *lower_page, struct inode *lower_inode, int byte_offset_in_page, int bytes_to_write) { int rc = 0; if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { rc = ecryptfs_commit_lower_page(lower_page, lower_inode, ctx->param.lower_file, byte_offset_in_page, bytes_to_write); if (rc) { ecryptfs_printk(KERN_ERR, "Error calling lower " "commit; rc = [%d]\n", rc); goto out; } } else { rc = ecryptfs_writepage_and_release_lower_page(lower_page, lower_inode, ctx->param.wbc); if (rc) { ecryptfs_printk(KERN_ERR, "Error calling lower " "writepage(); rc = [%d]\n", rc); goto out; } } out: return rc; } static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx, struct page **lower_page, struct inode *lower_inode, unsigned long lower_page_idx, int byte_offset_in_page) { int rc = 0; if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) { /* TODO: Limit this to only the data extents that are * needed */ rc = ecryptfs_get_lower_page(lower_page, lower_inode, ctx->param.lower_file, lower_page_idx, byte_offset_in_page, (PAGE_CACHE_SIZE - byte_offset_in_page)); if (rc) { ecryptfs_printk( KERN_ERR, "Error attempting to grab, map, " "and prepare_write lower page with index " "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc); goto out; } } else { *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_idx); if (!(*lower_page)) { rc = -EINVAL; ecryptfs_printk( KERN_ERR, "Error attempting to grab and map " "lower page with index [0x%.16x]; rc = [%d]\n", lower_page_idx, rc); goto out; } } out: return rc; } /** * ecryptfs_encrypt_page * @ctx: The context of the page * * Encrypt an eCryptfs page. This is done on a per-extent basis. Note * that eCryptfs pages may straddle the lower pages -- for instance, * if the file was created on a machine with an 8K page size * (resulting in an 8K header), and then the file is copied onto a * host with a 32K page size, then when reading page 0 of the eCryptfs * file, 24K of page 0 of the lower file will be read and decrypted, * and then 8K of page 1 of the lower file will be read and decrypted. * * The actual operations performed on each page depends on the * contents of the ecryptfs_page_crypt_context struct. * * Returns zero on success; negative on error */ int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx) { char extent_iv[ECRYPTFS_MAX_IV_BYTES]; unsigned long base_extent; unsigned long extent_offset = 0; unsigned long lower_page_idx = 0; unsigned long prior_lower_page_idx = 0; struct page *lower_page; struct inode *lower_inode; struct ecryptfs_inode_info *inode_info; struct ecryptfs_crypt_stat *crypt_stat; int rc = 0; int lower_byte_offset = 0; int orig_byte_offset = 0; int num_extents_per_page; #define ECRYPTFS_PAGE_STATE_UNREAD 0 #define ECRYPTFS_PAGE_STATE_READ 1 #define ECRYPTFS_PAGE_STATE_MODIFIED 2 #define ECRYPTFS_PAGE_STATE_WRITTEN 3 int page_state; lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host); inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host); crypt_stat = &inode_info->crypt_stat; if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode, ctx->param.lower_file); if (rc) ecryptfs_printk(KERN_ERR, "Error attempting to copy " "page at index [0x%.16x]\n", ctx->page->index); goto out; } num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; base_extent = (ctx->page->index * num_extents_per_page); page_state = ECRYPTFS_PAGE_STATE_UNREAD; while (extent_offset < num_extents_per_page) { ecryptfs_extent_to_lwr_pg_idx_and_offset( &lower_page_idx, &lower_byte_offset, crypt_stat, (base_extent + extent_offset)); if (prior_lower_page_idx != lower_page_idx && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) { rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, orig_byte_offset, (PAGE_CACHE_SIZE - orig_byte_offset)); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting " "to write out page; rc = [%d]" "\n", rc); goto out; } page_state = ECRYPTFS_PAGE_STATE_WRITTEN; } if (page_state == ECRYPTFS_PAGE_STATE_UNREAD || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) { rc = ecryptfs_read_in_page(ctx, &lower_page, lower_inode, lower_page_idx, lower_byte_offset); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting " "to read in lower page with " "index [0x%.16x]; rc = [%d]\n", lower_page_idx, rc); goto out; } orig_byte_offset = lower_byte_offset; prior_lower_page_idx = lower_page_idx; page_state = ECRYPTFS_PAGE_STATE_READ; } BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED || page_state == ECRYPTFS_PAGE_STATE_READ)); rc = ecryptfs_derive_iv(extent_iv, crypt_stat, (base_extent + extent_offset)); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting to " "derive IV for extent [0x%.16x]; " "rc = [%d]\n", (base_extent + extent_offset), rc); goto out; } if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Encrypting extent " "with iv:\n"); ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " "encryption:\n"); ecryptfs_dump_hex((char *) (page_address(ctx->page) + (extent_offset * crypt_stat->extent_size)), 8); } rc = ecryptfs_encrypt_page_offset( crypt_stat, lower_page, lower_byte_offset, ctx->page, (extent_offset * crypt_stat->extent_size), crypt_stat->extent_size, extent_iv); ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; " "rc = [%d]\n", (base_extent + extent_offset), rc); if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " "encryption:\n"); ecryptfs_dump_hex((char *)(page_address(lower_page) + lower_byte_offset), 8); } page_state = ECRYPTFS_PAGE_STATE_MODIFIED; extent_offset++; } BUG_ON(orig_byte_offset != 0); rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0, (lower_byte_offset + crypt_stat->extent_size)); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting to write out " "page; rc = [%d]\n", rc); goto out; } out: return rc; } /** * ecryptfs_decrypt_page * @file: The ecryptfs file * @page: The page in ecryptfs to decrypt * * Decrypt an eCryptfs page. This is done on a per-extent basis. Note * that eCryptfs pages may straddle the lower pages -- for instance, * if the file was created on a machine with an 8K page size * (resulting in an 8K header), and then the file is copied onto a * host with a 32K page size, then when reading page 0 of the eCryptfs * file, 24K of page 0 of the lower file will be read and decrypted, * and then 8K of page 1 of the lower file will be read and decrypted. * * Returns zero on success; negative on error */ int ecryptfs_decrypt_page(struct file *file, struct page *page) { char extent_iv[ECRYPTFS_MAX_IV_BYTES]; unsigned long base_extent; unsigned long extent_offset = 0; unsigned long lower_page_idx = 0; unsigned long prior_lower_page_idx = 0; struct page *lower_page; char *lower_page_virt = NULL; struct inode *lower_inode; struct ecryptfs_crypt_stat *crypt_stat; int rc = 0; int byte_offset; int num_extents_per_page; int page_state; crypt_stat = &(ecryptfs_inode_to_private( page->mapping->host)->crypt_stat); lower_inode = ecryptfs_inode_to_lower(page->mapping->host); if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { rc = ecryptfs_do_readpage(file, page, page->index); if (rc) ecryptfs_printk(KERN_ERR, "Error attempting to copy " "page at index [0x%.16x]\n", page->index); goto out; } num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size; base_extent = (page->index * num_extents_per_page); lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache, GFP_KERNEL); if (!lower_page_virt) { rc = -ENOMEM; ecryptfs_printk(KERN_ERR, "Error getting page for encrypted " "lower page(s)\n"); goto out; } lower_page = virt_to_page(lower_page_virt); page_state = ECRYPTFS_PAGE_STATE_UNREAD; while (extent_offset < num_extents_per_page) { ecryptfs_extent_to_lwr_pg_idx_and_offset( &lower_page_idx, &byte_offset, crypt_stat, (base_extent + extent_offset)); if (prior_lower_page_idx != lower_page_idx || page_state == ECRYPTFS_PAGE_STATE_UNREAD) { rc = ecryptfs_do_readpage(file, lower_page, lower_page_idx); if (rc) { ecryptfs_printk(KERN_ERR, "Error reading " "lower encrypted page; rc = " "[%d]\n", rc); goto out; } prior_lower_page_idx = lower_page_idx; page_state = ECRYPTFS_PAGE_STATE_READ; } rc = ecryptfs_derive_iv(extent_iv, crypt_stat, (base_extent + extent_offset)); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting to " "derive IV for extent [0x%.16x]; rc = " "[%d]\n", (base_extent + extent_offset), rc); goto out; } if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Decrypting extent " "with iv:\n"); ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes); ecryptfs_printk(KERN_DEBUG, "First 8 bytes before " "decryption:\n"); ecryptfs_dump_hex((lower_page_virt + byte_offset), 8); } rc = ecryptfs_decrypt_page_offset(crypt_stat, page, (extent_offset * crypt_stat->extent_size), lower_page, byte_offset, crypt_stat->extent_size, extent_iv); if (rc != crypt_stat->extent_size) { ecryptfs_printk(KERN_ERR, "Error attempting to " "decrypt extent [0x%.16x]\n", (base_extent + extent_offset)); goto out; } rc = 0; if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "First 8 bytes after " "decryption:\n"); ecryptfs_dump_hex((char *)(page_address(page) + byte_offset), 8); } extent_offset++; } out: if (lower_page_virt) kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt); return rc; } /** * decrypt_scatterlist * * Returns the number of bytes decrypted; negative value on error */ static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat, struct scatterlist *dest_sg, struct scatterlist *src_sg, int size, unsigned char *iv) { struct blkcipher_desc desc = { .tfm = crypt_stat->tfm, .info = iv, .flags = CRYPTO_TFM_REQ_MAY_SLEEP }; int rc = 0; /* Consider doing this once, when the file is opened */ mutex_lock(&crypt_stat->cs_tfm_mutex); rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key, crypt_stat->key_size); if (rc) { ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n", rc); mutex_unlock(&crypt_stat->cs_tfm_mutex); rc = -EINVAL; goto out; } ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size); rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size); mutex_unlock(&crypt_stat->cs_tfm_mutex); if (rc) { ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n", rc); goto out; } rc = size; out: return rc; } /** * ecryptfs_encrypt_page_offset * * Returns the number of bytes encrypted */ static int ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, struct page *dst_page, int dst_offset, struct page *src_page, int src_offset, int size, unsigned char *iv) { struct scatterlist src_sg, dst_sg; src_sg.page = src_page; src_sg.offset = src_offset; src_sg.length = size; dst_sg.page = dst_page; dst_sg.offset = dst_offset; dst_sg.length = size; return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); } /** * ecryptfs_decrypt_page_offset * * Returns the number of bytes decrypted */ static int ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat, struct page *dst_page, int dst_offset, struct page *src_page, int src_offset, int size, unsigned char *iv) { struct scatterlist src_sg, dst_sg; src_sg.page = src_page; src_sg.offset = src_offset; src_sg.length = size; dst_sg.page = dst_page; dst_sg.offset = dst_offset; dst_sg.length = size; return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv); } #define ECRYPTFS_MAX_SCATTERLIST_LEN 4 /** * ecryptfs_init_crypt_ctx * @crypt_stat: Uninitilized crypt stats structure * * Initialize the crypto context. * * TODO: Performance: Keep a cache of initialized cipher contexts; * only init if needed */ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat) { char *full_alg_name; int rc = -EINVAL; if (!crypt_stat->cipher) { ecryptfs_printk(KERN_ERR, "No cipher specified\n"); goto out; } ecryptfs_printk(KERN_DEBUG, "Initializing cipher [%s]; strlen = [%d]; " "key_size_bits = [%d]\n", crypt_stat->cipher, (int)strlen(crypt_stat->cipher), crypt_stat->key_size << 3); if (crypt_stat->tfm) { rc = 0; goto out; } mutex_lock(&crypt_stat->cs_tfm_mutex); rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, crypt_stat->cipher, "cbc"); if (rc) goto out; crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC); kfree(full_alg_name); if (IS_ERR(crypt_stat->tfm)) { rc = PTR_ERR(crypt_stat->tfm); ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " "Error initializing cipher [%s]\n", crypt_stat->cipher); mutex_unlock(&crypt_stat->cs_tfm_mutex); goto out; } crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY); mutex_unlock(&crypt_stat->cs_tfm_mutex); rc = 0; out: return rc; } static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat) { int extent_size_tmp; crypt_stat->extent_mask = 0xFFFFFFFF; crypt_stat->extent_shift = 0; if (crypt_stat->extent_size == 0) return; extent_size_tmp = crypt_stat->extent_size; while ((extent_size_tmp & 0x01) == 0) { extent_size_tmp >>= 1; crypt_stat->extent_mask <<= 1; crypt_stat->extent_shift++; } } void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat) { /* Default values; may be overwritten as we are parsing the * packets. */ crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE; set_extent_mask_and_shift(crypt_stat); crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES; if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) { crypt_stat->header_extent_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE; } else crypt_stat->header_extent_size = PAGE_CACHE_SIZE; if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) crypt_stat->num_header_extents_at_front = 0; else crypt_stat->num_header_extents_at_front = 1; } /** * ecryptfs_compute_root_iv * @crypt_stats * * On error, sets the root IV to all 0's. */ int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat) { int rc = 0; char dst[MD5_DIGEST_SIZE]; BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE); BUG_ON(crypt_stat->iv_bytes <= 0); if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { rc = -EINVAL; ecryptfs_printk(KERN_WARNING, "Session key not valid; " "cannot generate root IV\n"); goto out; } rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key, crypt_stat->key_size); if (rc) { ecryptfs_printk(KERN_WARNING, "Error attempting to compute " "MD5 while generating root IV\n"); goto out; } memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes); out: if (rc) { memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes); crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING; } return rc; } static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat) { get_random_bytes(crypt_stat->key, crypt_stat->key_size); crypt_stat->flags |= ECRYPTFS_KEY_VALID; ecryptfs_compute_root_iv(crypt_stat); if (unlikely(ecryptfs_verbosity > 0)) { ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n"); ecryptfs_dump_hex(crypt_stat->key, crypt_stat->key_size); } } /** * ecryptfs_copy_mount_wide_flags_to_inode_flags * * This function propagates the mount-wide flags to individual inode * flags. */ static void ecryptfs_copy_mount_wide_flags_to_inode_flags( struct ecryptfs_crypt_stat *crypt_stat, struct ecryptfs_mount_crypt_stat *mount_crypt_stat) { if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR; if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED; } /** * ecryptfs_set_default_crypt_stat_vals * @crypt_stat * * Default values in the event that policy does not override them. */ static void ecryptfs_set_default_crypt_stat_vals( struct ecryptfs_crypt_stat *crypt_stat, struct ecryptfs_mount_crypt_stat *mount_crypt_stat) { ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, mount_crypt_stat); ecryptfs_set_default_sizes(crypt_stat); strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER); crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES; crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID); crypt_stat->file_version = ECRYPTFS_FILE_VERSION; crypt_stat->mount_crypt_stat = mount_crypt_stat; } /** * ecryptfs_new_file_context * @ecryptfs_dentry * * If the crypto context for the file has not yet been established, * this is where we do that. Establishing a new crypto context * involves the following decisions: * - What cipher to use? * - What set of authentication tokens to use? * Here we just worry about getting enough information into the * authentication tokens so that we know that they are available. * We associate the available authentication tokens with the new file * via the set of signatures in the crypt_stat struct. Later, when * the headers are actually written out, we may again defer to * userspace to perform the encryption of the session key; for the * foreseeable future, this will be the case with public key packets. * * Returns zero on success; non-zero otherwise */ /* Associate an authentication token(s) with the file */ int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry) { int rc = 0; struct ecryptfs_crypt_stat *crypt_stat = &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = &ecryptfs_superblock_to_private( ecryptfs_dentry->d_sb)->mount_crypt_stat; int cipher_name_len; ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat); /* See if there are mount crypt options */ if (mount_crypt_stat->global_auth_tok) { ecryptfs_printk(KERN_DEBUG, "Initializing context for new " "file using mount_crypt_stat\n"); crypt_stat->flags |= ECRYPTFS_ENCRYPTED; crypt_stat->flags |= ECRYPTFS_KEY_VALID; ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, mount_crypt_stat); memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++], mount_crypt_stat->global_auth_tok_sig, ECRYPTFS_SIG_SIZE_HEX); cipher_name_len = strlen(mount_crypt_stat->global_default_cipher_name); memcpy(crypt_stat->cipher, mount_crypt_stat->global_default_cipher_name, cipher_name_len); crypt_stat->cipher[cipher_name_len] = '\0'; crypt_stat->key_size = mount_crypt_stat->global_default_cipher_key_size; ecryptfs_generate_new_key(crypt_stat); } else /* We should not encounter this scenario since we * should detect lack of global_auth_tok at mount time * TODO: Applies to 0.1 release only; remove in future * release */ BUG(); rc = ecryptfs_init_crypt_ctx(crypt_stat); if (rc) ecryptfs_printk(KERN_ERR, "Error initializing cryptographic " "context for cipher [%s]: rc = [%d]\n", crypt_stat->cipher, rc); return rc; } /** * contains_ecryptfs_marker - check for the ecryptfs marker * @data: The data block in which to check * * Returns one if marker found; zero if not found */ static int contains_ecryptfs_marker(char *data) { u32 m_1, m_2; memcpy(&m_1, data, 4); m_1 = be32_to_cpu(m_1); memcpy(&m_2, (data + 4), 4); m_2 = be32_to_cpu(m_2); if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2) return 1; ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; " "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2, MAGIC_ECRYPTFS_MARKER); ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = " "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER)); return 0; } struct ecryptfs_flag_map_elem { u32 file_flag; u32 local_flag; }; /* Add support for additional flags by adding elements here. */ static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = { {0x00000001, ECRYPTFS_ENABLE_HMAC}, {0x00000002, ECRYPTFS_ENCRYPTED}, {0x00000004, ECRYPTFS_METADATA_IN_XATTR} }; /** * ecryptfs_process_flags * @crypt_stat * @page_virt: Source data to be parsed * @bytes_read: Updated with the number of bytes read * * Returns zero on success; non-zero if the flag set is invalid */ static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat, char *page_virt, int *bytes_read) { int rc = 0; int i; u32 flags; memcpy(&flags, page_virt, 4); flags = be32_to_cpu(flags); for (i = 0; i < ((sizeof(ecryptfs_flag_map) / sizeof(struct ecryptfs_flag_map_elem))); i++) if (flags & ecryptfs_flag_map[i].file_flag) { crypt_stat->flags |= ecryptfs_flag_map[i].local_flag; } else crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag); /* Version is in top 8 bits of the 32-bit flag vector */ crypt_stat->file_version = ((flags >> 24) & 0xFF); (*bytes_read) = 4; return rc; } /** * write_ecryptfs_marker * @page_virt: The pointer to in a page to begin writing the marker * @written: Number of bytes written * * Marker = 0x3c81b7f5 */ static void write_ecryptfs_marker(char *page_virt, size_t *written) { u32 m_1, m_2; get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER); m_1 = cpu_to_be32(m_1); memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); m_2 = cpu_to_be32(m_2); memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2)); (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; } static void write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat, size_t *written) { u32 flags = 0; int i; for (i = 0; i < ((sizeof(ecryptfs_flag_map) / sizeof(struct ecryptfs_flag_map_elem))); i++) if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag) flags |= ecryptfs_flag_map[i].file_flag; /* Version is in top 8 bits of the 32-bit flag vector */ flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000); flags = cpu_to_be32(flags); memcpy(page_virt, &flags, 4); (*written) = 4; } struct ecryptfs_cipher_code_str_map_elem { char cipher_str[16]; u16 cipher_code; }; /* Add support for additional ciphers by adding elements here. The * cipher_code is whatever OpenPGP applicatoins use to identify the * ciphers. List in order of probability. */ static struct ecryptfs_cipher_code_str_map_elem ecryptfs_cipher_code_str_map[] = { {"aes",RFC2440_CIPHER_AES_128 }, {"blowfish", RFC2440_CIPHER_BLOWFISH}, {"des3_ede", RFC2440_CIPHER_DES3_EDE}, {"cast5", RFC2440_CIPHER_CAST_5}, {"twofish", RFC2440_CIPHER_TWOFISH}, {"cast6", RFC2440_CIPHER_CAST_6}, {"aes", RFC2440_CIPHER_AES_192}, {"aes", RFC2440_CIPHER_AES_256} }; /** * ecryptfs_code_for_cipher_string * @str: The string representing the cipher name * * Returns zero on no match, or the cipher code on match */ u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat) { int i; u16 code = 0; struct ecryptfs_cipher_code_str_map_elem *map = ecryptfs_cipher_code_str_map; if (strcmp(crypt_stat->cipher, "aes") == 0) { switch (crypt_stat->key_size) { case 16: code = RFC2440_CIPHER_AES_128; break; case 24: code = RFC2440_CIPHER_AES_192; break; case 32: code = RFC2440_CIPHER_AES_256; } } else { for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){ code = map[i].cipher_code; break; } } return code; } /** * ecryptfs_cipher_code_to_string * @str: Destination to write out the cipher name * @cipher_code: The code to convert to cipher name string * * Returns zero on success */ int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code) { int rc = 0; int i; str[0] = '\0'; for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++) if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code) strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str); if (str[0] == '\0') { ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: " "[%d]\n", cipher_code); rc = -EINVAL; } return rc; } /** * ecryptfs_read_header_region * @data * @dentry * @nd * * Returns zero on success; non-zero otherwise */ static int ecryptfs_read_header_region(char *data, struct dentry *dentry, struct vfsmount *mnt) { struct file *lower_file; mm_segment_t oldfs; int rc; if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt, O_RDONLY))) { printk(KERN_ERR "Error opening lower_file to read header region\n"); goto out; } lower_file->f_pos = 0; oldfs = get_fs(); set_fs(get_ds()); /* For releases 0.1 and 0.2, all of the header information * fits in the first data extent-sized region. */ rc = lower_file->f_op->read(lower_file, (char __user *)data, ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos); set_fs(oldfs); if ((rc = ecryptfs_close_lower_file(lower_file))) { printk(KERN_ERR "Error closing lower_file\n"); goto out; } rc = 0; out: return rc; } int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry, struct vfsmount *mnt) { int rc; rc = ecryptfs_read_header_region(data, dentry, mnt); if (rc) goto out; if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES)) rc = -EINVAL; out: return rc; } void ecryptfs_write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat, size_t *written) { u32 header_extent_size; u16 num_header_extents_at_front; header_extent_size = (u32)crypt_stat->header_extent_size; num_header_extents_at_front = (u16)crypt_stat->num_header_extents_at_front; header_extent_size = cpu_to_be32(header_extent_size); memcpy(virt, &header_extent_size, 4); virt += 4; num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front); memcpy(virt, &num_header_extents_at_front, 2); (*written) = 6; } struct kmem_cache *ecryptfs_header_cache_0; struct kmem_cache *ecryptfs_header_cache_1; struct kmem_cache *ecryptfs_header_cache_2; /** * ecryptfs_write_headers_virt * @page_virt * @crypt_stat * @ecryptfs_dentry * * Format version: 1 * * Header Extent: * Octets 0-7: Unencrypted file size (big-endian) * Octets 8-15: eCryptfs special marker * Octets 16-19: Flags * Octet 16: File format version number (between 0 and 255) * Octets 17-18: Reserved * Octet 19: Bit 1 (lsb): Reserved * Bit 2: Encrypted? * Bits 3-8: Reserved * Octets 20-23: Header extent size (big-endian) * Octets 24-25: Number of header extents at front of file * (big-endian) * Octet 26: Begin RFC 2440 authentication token packet set * Data Extent 0: * Lower data (CBC encrypted) * Data Extent 1: * Lower data (CBC encrypted) * ... * * Returns zero on success */ static int ecryptfs_write_headers_virt(char *page_virt, size_t *size, struct ecryptfs_crypt_stat *crypt_stat, struct dentry *ecryptfs_dentry) { int rc; size_t written; size_t offset; offset = ECRYPTFS_FILE_SIZE_BYTES; write_ecryptfs_marker((page_virt + offset), &written); offset += written; write_ecryptfs_flags((page_virt + offset), crypt_stat, &written); offset += written; ecryptfs_write_header_metadata((page_virt + offset), crypt_stat, &written); offset += written; rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat, ecryptfs_dentry, &written, PAGE_CACHE_SIZE - offset); if (rc) ecryptfs_printk(KERN_WARNING, "Error generating key packet " "set; rc = [%d]\n", rc); if (size) { offset += written; *size = offset; } return rc; } static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat, struct file *lower_file, char *page_virt) { mm_segment_t oldfs; int current_header_page; int header_pages; ssize_t size; int rc = 0; lower_file->f_pos = 0; oldfs = get_fs(); set_fs(get_ds()); size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE, &lower_file->f_pos); if (size < 0) { rc = (int)size; printk(KERN_ERR "Error attempting to write lower page; " "rc = [%d]\n", rc); set_fs(oldfs); goto out; } header_pages = ((crypt_stat->header_extent_size * crypt_stat->num_header_extents_at_front) / PAGE_CACHE_SIZE); memset(page_virt, 0, PAGE_CACHE_SIZE); current_header_page = 1; while (current_header_page < header_pages) { size = vfs_write(lower_file, (char __user *)page_virt, PAGE_CACHE_SIZE, &lower_file->f_pos); if (size < 0) { rc = (int)size; printk(KERN_ERR "Error attempting to write lower page; " "rc = [%d]\n", rc); set_fs(oldfs); goto out; } current_header_page++; } set_fs(oldfs); out: return rc; } static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry, struct ecryptfs_crypt_stat *crypt_stat, char *page_virt, size_t size) { int rc; rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt, size, 0); return rc; } /** * ecryptfs_write_metadata * @lower_file: The lower file struct, which was returned from dentry_open * * Write the file headers out. This will likely involve a userspace * callout, in which the session key is encrypted with one or more * public keys and/or the passphrase necessary to do the encryption is * retrieved via a prompt. Exactly what happens at this point should * be policy-dependent. * * Returns zero on success; non-zero on error */ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry, struct file *lower_file) { struct ecryptfs_crypt_stat *crypt_stat; char *page_virt; size_t size; int rc = 0; crypt_stat = &ecryptfs_inode_to_private( ecryptfs_dentry->d_inode)->crypt_stat; if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { ecryptfs_printk(KERN_DEBUG, "Key is " "invalid; bailing out\n"); rc = -EINVAL; goto out; } } else { rc = -EINVAL; ecryptfs_printk(KERN_WARNING, "Called with crypt_stat->encrypted == 0\n"); goto out; } /* Released in this function */ page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER); if (!page_virt) { ecryptfs_printk(KERN_ERR, "Out of memory\n"); rc = -ENOMEM; goto out; } rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat, ecryptfs_dentry); if (unlikely(rc)) { ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n"); memset(page_virt, 0, PAGE_CACHE_SIZE); goto out_free; } if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, crypt_stat, page_virt, size); else rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file, page_virt); if (rc) { printk(KERN_ERR "Error writing metadata out to lower file; " "rc = [%d]\n", rc); goto out_free; } out_free: kmem_cache_free(ecryptfs_header_cache_0, page_virt); out: return rc; } #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat, char *virt, int *bytes_read, int validate_header_size) { int rc = 0; u32 header_extent_size; u16 num_header_extents_at_front; memcpy(&header_extent_size, virt, 4); header_extent_size = be32_to_cpu(header_extent_size); virt += 4; memcpy(&num_header_extents_at_front, virt, 2); num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front); crypt_stat->header_extent_size = (int)header_extent_size; crypt_stat->num_header_extents_at_front = (int)num_header_extents_at_front; (*bytes_read) = 6; if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE) && ((crypt_stat->header_extent_size * crypt_stat->num_header_extents_at_front) < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) { rc = -EINVAL; ecryptfs_printk(KERN_WARNING, "Invalid header extent size: " "[%d]\n", crypt_stat->header_extent_size); } return rc; } /** * set_default_header_data * * For version 0 file format; this function is only for backwards * compatibility for files created with the prior versions of * eCryptfs. */ static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat) { crypt_stat->header_extent_size = 4096; crypt_stat->num_header_extents_at_front = 1; } /** * ecryptfs_read_headers_virt * * Read/parse the header data. The header format is detailed in the * comment block for the ecryptfs_write_headers_virt() function. * * Returns zero on success */ static int ecryptfs_read_headers_virt(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat, struct dentry *ecryptfs_dentry, int validate_header_size) { int rc = 0; int offset; int bytes_read; ecryptfs_set_default_sizes(crypt_stat); crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private( ecryptfs_dentry->d_sb)->mount_crypt_stat; offset = ECRYPTFS_FILE_SIZE_BYTES; rc = contains_ecryptfs_marker(page_virt + offset); if (rc == 0) { rc = -EINVAL; goto out; } offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES; rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read); if (rc) { ecryptfs_printk(KERN_WARNING, "Error processing flags\n"); goto out; } if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) { ecryptfs_printk(KERN_WARNING, "File version is [%d]; only " "file version [%d] is supported by this " "version of eCryptfs\n", crypt_stat->file_version, ECRYPTFS_SUPPORTED_FILE_VERSION); rc = -EINVAL; goto out; } offset += bytes_read; if (crypt_stat->file_version >= 1) { rc = parse_header_metadata(crypt_stat, (page_virt + offset), &bytes_read, validate_header_size); if (rc) { ecryptfs_printk(KERN_WARNING, "Error reading header " "metadata; rc = [%d]\n", rc); } offset += bytes_read; } else set_default_header_data(crypt_stat); rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset), ecryptfs_dentry); out: return rc; } /** * ecryptfs_read_xattr_region * * Attempts to read the crypto metadata from the extended attribute * region of the lower file. */ int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry) { ssize_t size; int rc = 0; size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE); if (size < 0) { printk(KERN_DEBUG "Error attempting to read the [%s] " "xattr from the lower file; return value = [%zd]\n", ECRYPTFS_XATTR_NAME, size); rc = -EINVAL; goto out; } out: return rc; } int ecryptfs_read_and_validate_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry) { int rc; rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry); if (rc) goto out; if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) { printk(KERN_WARNING "Valid data found in [%s] xattr, but " "the marker is invalid\n", ECRYPTFS_XATTR_NAME); rc = -EINVAL; } out: return rc; } /** * ecryptfs_read_metadata * * Common entry point for reading file metadata. From here, we could * retrieve the header information from the header region of the file, * the xattr region of the file, or some other repostory that is * stored separately from the file itself. The current implementation * supports retrieving the metadata information from the file contents * and from the xattr region. * * Returns zero if valid headers found and parsed; non-zero otherwise */ int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry, struct file *lower_file) { int rc = 0; char *page_virt = NULL; mm_segment_t oldfs; ssize_t bytes_read; struct ecryptfs_crypt_stat *crypt_stat = &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat; struct ecryptfs_mount_crypt_stat *mount_crypt_stat = &ecryptfs_superblock_to_private( ecryptfs_dentry->d_sb)->mount_crypt_stat; ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat, mount_crypt_stat); /* Read the first page from the underlying file */ page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER); if (!page_virt) { rc = -ENOMEM; ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n"); goto out; } lower_file->f_pos = 0; oldfs = get_fs(); set_fs(get_ds()); bytes_read = lower_file->f_op->read(lower_file, (char __user *)page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos); set_fs(oldfs); if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) { rc = -EINVAL; goto out; } rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, ecryptfs_dentry, ECRYPTFS_VALIDATE_HEADER_SIZE); if (rc) { rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry); if (rc) { printk(KERN_DEBUG "Valid eCryptfs headers not found in " "file header region or xattr region\n"); rc = -EINVAL; goto out; } rc = ecryptfs_read_headers_virt(page_virt, crypt_stat, ecryptfs_dentry, ECRYPTFS_DONT_VALIDATE_HEADER_SIZE); if (rc) { printk(KERN_DEBUG "Valid eCryptfs headers not found in " "file xattr region either\n"); rc = -EINVAL; } if (crypt_stat->mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) { crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR; } else { printk(KERN_WARNING "Attempt to access file with " "crypto metadata only in the extended attribute " "region, but eCryptfs was mounted without " "xattr support enabled. eCryptfs will not treat " "this like an encrypted file.\n"); rc = -EINVAL; } } out: if (page_virt) { memset(page_virt, 0, PAGE_CACHE_SIZE); kmem_cache_free(ecryptfs_header_cache_1, page_virt); } return rc; } /** * ecryptfs_encode_filename - converts a plaintext file name to cipher text * @crypt_stat: The crypt_stat struct associated with the file anem to encode * @name: The plaintext name * @length: The length of the plaintext * @encoded_name: The encypted name * * Encrypts and encodes a filename into something that constitutes a * valid filename for a filesystem, with printable characters. * * We assume that we have a properly initialized crypto context, * pointed to by crypt_stat->tfm. * * TODO: Implement filename decoding and decryption here, in place of * memcpy. We are keeping the framework around for now to (1) * facilitate testing of the components needed to implement filename * encryption and (2) to provide a code base from which other * developers in the community can easily implement this feature. * * Returns the length of encoded filename; negative if error */ int ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat, const char *name, int length, char **encoded_name) { int error = 0; (*encoded_name) = kmalloc(length + 2, GFP_KERNEL); if (!(*encoded_name)) { error = -ENOMEM; goto out; } /* TODO: Filename encryption is a scheduled feature for a * future version of eCryptfs. This function is here only for * the purpose of providing a framework for other developers * to easily implement filename encryption. Hint: Replace this * memcpy() with a call to encrypt and encode the * filename, the set the length accordingly. */ memcpy((void *)(*encoded_name), (void *)name, length); (*encoded_name)[length] = '\0'; error = length + 1; out: return error; } /** * ecryptfs_decode_filename - converts the cipher text name to plaintext * @crypt_stat: The crypt_stat struct associated with the file * @name: The filename in cipher text * @length: The length of the cipher text name * @decrypted_name: The plaintext name * * Decodes and decrypts the filename. * * We assume that we have a properly initialized crypto context, * pointed to by crypt_stat->tfm. * * TODO: Implement filename decoding and decryption here, in place of * memcpy. We are keeping the framework around for now to (1) * facilitate testing of the components needed to implement filename * encryption and (2) to provide a code base from which other * developers in the community can easily implement this feature. * * Returns the length of decoded filename; negative if error */ int ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat, const char *name, int length, char **decrypted_name) { int error = 0; (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL); if (!(*decrypted_name)) { error = -ENOMEM; goto out; } /* TODO: Filename encryption is a scheduled feature for a * future version of eCryptfs. This function is here only for * the purpose of providing a framework for other developers * to easily implement filename encryption. Hint: Replace this * memcpy() with a call to decode and decrypt the * filename, the set the length accordingly. */ memcpy((void *)(*decrypted_name), (void *)name, length); (*decrypted_name)[length + 1] = '\0'; /* Only for convenience * in printing out the * string in debug * messages */ error = length; out: return error; } /** * ecryptfs_process_cipher - Perform cipher initialization. * @key_tfm: Crypto context for key material, set by this function * @cipher_name: Name of the cipher * @key_size: Size of the key in bytes * * Returns zero on success. Any crypto_tfm structs allocated here * should be released by other functions, such as on a superblock put * event, regardless of whether this function succeeds for fails. */ int ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name, size_t *key_size) { char dummy_key[ECRYPTFS_MAX_KEY_BYTES]; char *full_alg_name; int rc; *key_tfm = NULL; if (*key_size > ECRYPTFS_MAX_KEY_BYTES) { rc = -EINVAL; printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum " "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES); goto out; } rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name, "ecb"); if (rc) goto out; *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC); kfree(full_alg_name); if (IS_ERR(*key_tfm)) { rc = PTR_ERR(*key_tfm); printk(KERN_ERR "Unable to allocate crypto cipher with name " "[%s]; rc = [%d]\n", cipher_name, rc); goto out; } crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY); if (*key_size == 0) { struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm); *key_size = alg->max_keysize; } get_random_bytes(dummy_key, *key_size); rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size); if (rc) { printk(KERN_ERR "Error attempting to set key of size [%Zd] for " "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc); rc = -EINVAL; goto out; } out: return rc; }