diff options
Diffstat (limited to 'fs/ecryptfs/crypto.c')
| -rw-r--r-- | fs/ecryptfs/crypto.c | 1659 |
1 files changed, 1659 insertions, 0 deletions
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c new file mode 100644 index 000000000000..ed35a9712fa1 --- /dev/null +++ b/fs/ecryptfs/crypto.c @@ -0,0 +1,1659 @@ +/** + * eCryptfs: Linux filesystem encryption layer + * + * Copyright (C) 1997-2004 Erez Zadok + * Copyright (C) 2001-2004 Stony Brook University + * Copyright (C) 2004-2006 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) +{ + int rc = 0; + struct scatterlist sg; + + mutex_lock(&crypt_stat->cs_md5_tfm_mutex); + sg_init_one(&sg, (u8 *)src, len); + if (!crypt_stat->md5_tfm) { + crypt_stat->md5_tfm = + crypto_alloc_tfm("md5", CRYPTO_TFM_REQ_MAY_SLEEP); + if (!crypt_stat->md5_tfm) { + rc = -ENOMEM; + ecryptfs_printk(KERN_ERR, "Error attempting to " + "allocate crypto context\n"); + goto out; + } + } + crypto_digest_init(crypt_stat->md5_tfm); + crypto_digest_update(crypt_stat->md5_tfm, &sg, 1); + crypto_digest_final(crypt_stat->md5_tfm, dst); + mutex_unlock(&crypt_stat->cs_md5_tfm_mutex); +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_md5_tfm_mutex); + ECRYPTFS_SET_FLAG(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_tfm(crypt_stat->tfm); + if (crypt_stat->md5_tfm) + crypto_free_tfm(crypt_stat->md5_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_tfm(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) +{ + int rc = 0; + + BUG_ON(!crypt_stat || !crypt_stat->tfm + || !ECRYPTFS_CHECK_FLAG(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_cipher_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_cipher_encrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, iv); + 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 { + rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, + lower_inode, + lower_page_idx); + if (rc) { + 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 (!ECRYPTFS_CHECK_FLAG(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 (!ECRYPTFS_CHECK_FLAG(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, + SLAB_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) +{ + int rc = 0; + + /* Consider doing this once, when the file is opened */ + mutex_lock(&crypt_stat->cs_tfm_mutex); + rc = crypto_cipher_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_cipher_decrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, + iv); + 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) +{ + 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); + crypt_stat->tfm = crypto_alloc_tfm(crypt_stat->cipher, + ECRYPTFS_DEFAULT_CHAINING_MODE + | CRYPTO_TFM_REQ_WEAK_KEY); + mutex_unlock(&crypt_stat->cs_tfm_mutex); + if (!crypt_stat->tfm) { + ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): " + "Error initializing cipher [%s]\n", + crypt_stat->cipher); + goto out; + } + 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; + 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 (!ECRYPTFS_CHECK_FLAG(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); + ECRYPTFS_SET_FLAG(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); + ECRYPTFS_SET_FLAG(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_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_set_default_sizes(crypt_stat); + strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER); + crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES; + ECRYPTFS_CLEAR_FLAG(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"); + ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED); + ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID); + 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 + */ +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} +}; + +/** + * 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) { + ECRYPTFS_SET_FLAG(crypt_stat->flags, + ecryptfs_flag_map[i].local_flag); + } else + ECRYPTFS_CLEAR_FLAG(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 (ECRYPTFS_CHECK_FLAG(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 + */ +int ecryptfs_read_header_region(char *data, struct dentry *dentry, + struct vfsmount *mnt) +{ + struct file *file; + mm_segment_t oldfs; + int rc; + + mnt = mntget(mnt); + file = dentry_open(dentry, mnt, O_RDONLY); + if (IS_ERR(file)) { + ecryptfs_printk(KERN_DEBUG, "Error opening file to " + "read header region\n"); + mntput(mnt); + rc = PTR_ERR(file); + goto out; + } + 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 = file->f_op->read(file, (char __user *)data, + ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos); + set_fs(oldfs); + fput(file); + rc = 0; +out: + return rc; +} + +static void +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 + */ +int ecryptfs_write_headers_virt(char *page_virt, + 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; + 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); + return rc; +} + +/** + * ecryptfs_write_headers + * @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_headers(struct dentry *ecryptfs_dentry, + struct file *lower_file) +{ + mm_segment_t oldfs; + struct ecryptfs_crypt_stat *crypt_stat; + char *page_virt; + int current_header_page; + int header_pages; + int rc = 0; + + crypt_stat = &ecryptfs_inode_to_private( + ecryptfs_dentry->d_inode)->crypt_stat; + if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags, + ECRYPTFS_ENCRYPTED))) { + if (!ECRYPTFS_CHECK_FLAG(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_alloc(ecryptfs_header_cache_0, SLAB_USER); + if (!page_virt) { + ecryptfs_printk(KERN_ERR, "Out of memory\n"); + rc = -ENOMEM; + goto out; + } + memset(page_virt, 0, PAGE_CACHE_SIZE); + rc = ecryptfs_write_headers_virt(page_virt, 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; + } + ecryptfs_printk(KERN_DEBUG, + "Writing key packet set to underlying file\n"); + lower_file->f_pos = 0; + oldfs = get_fs(); + set_fs(get_ds()); + ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" + "write() w/ header page; lower_file->f_pos = " + "[0x%.16x]\n", lower_file->f_pos); + lower_file->f_op->write(lower_file, (char __user *)page_virt, + PAGE_CACHE_SIZE, &lower_file->f_pos); + 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) { + ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->" + "write() w/ zero'd page; lower_file->f_pos = " + "[0x%.16x]\n", lower_file->f_pos); + lower_file->f_op->write(lower_file, (char __user *)page_virt, + PAGE_CACHE_SIZE, &lower_file->f_pos); + current_header_page++; + } + set_fs(oldfs); + ecryptfs_printk(KERN_DEBUG, + "Done writing key packet set to underlying file.\n"); +out_free: + kmem_cache_free(ecryptfs_header_cache_0, page_virt); +out: + return rc; +} + +static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat, + char *virt, int *bytes_read) +{ + 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 ((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 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); + 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_headers + * + * Returns zero if valid headers found and parsed; non-zero otherwise + */ +int ecryptfs_read_headers(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; + + /* Read the first page from the underlying file */ + page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_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); + if (rc) { + ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not " + "found\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. + * @tfm: Crypto context set by this function + * @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_tfm **tfm, struct crypto_tfm **key_tfm, + char *cipher_name, size_t key_size) +{ + char dummy_key[ECRYPTFS_MAX_KEY_BYTES]; + int rc; + + *tfm = *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; + } + *tfm = crypto_alloc_tfm(cipher_name, (ECRYPTFS_DEFAULT_CHAINING_MODE + | CRYPTO_TFM_REQ_WEAK_KEY)); + if (!(*tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Unable to allocate crypto cipher with name " + "[%s]\n", cipher_name); + goto out; + } + *key_tfm = crypto_alloc_tfm(cipher_name, CRYPTO_TFM_REQ_WEAK_KEY); + if (!(*key_tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Unable to allocate crypto cipher with name " + "[%s]\n", cipher_name); + goto out; + } + if (key_size < crypto_tfm_alg_min_keysize(*tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Request key size is [%Zd]; minimum key size " + "supported by cipher [%s] is [%d]\n", key_size, + cipher_name, crypto_tfm_alg_min_keysize(*tfm)); + goto out; + } + if (key_size < crypto_tfm_alg_min_keysize(*key_tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Request key size is [%Zd]; minimum key size " + "supported by cipher [%s] is [%d]\n", key_size, + cipher_name, crypto_tfm_alg_min_keysize(*key_tfm)); + goto out; + } + if (key_size > crypto_tfm_alg_max_keysize(*tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Request key size is [%Zd]; maximum key size " + "supported by cipher [%s] is [%d]\n", key_size, + cipher_name, crypto_tfm_alg_min_keysize(*tfm)); + goto out; + } + if (key_size > crypto_tfm_alg_max_keysize(*key_tfm)) { + rc = -EINVAL; + printk(KERN_ERR "Request key size is [%Zd]; maximum key size " + "supported by cipher [%s] is [%d]\n", key_size, + cipher_name, crypto_tfm_alg_min_keysize(*key_tfm)); + goto out; + } + get_random_bytes(dummy_key, key_size); + rc = crypto_cipher_setkey(*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; + } + rc = crypto_cipher_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; +} |