/** * eCryptfs: Linux filesystem encryption layer * This is where eCryptfs coordinates the symmetric encryption and * decryption of the file data as it passes between the lower * encrypted file and the upper decrypted file. * * Copyright (C) 1997-2003 Erez Zadok * Copyright (C) 2001-2003 Stony Brook University * Copyright (C) 2004-2006 International Business Machines Corp. * Author(s): Michael A. Halcrow <mahalcro@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/pagemap.h> #include <linux/writeback.h> #include <linux/page-flags.h> #include <linux/mount.h> #include <linux/file.h> #include <linux/crypto.h> #include <linux/scatterlist.h> #include "ecryptfs_kernel.h" struct kmem_cache *ecryptfs_lower_page_cache; /** * ecryptfs_get1page * * Get one page from cache or lower f/s, return error otherwise. * * Returns unlocked and up-to-date page (if ok), with increased * refcnt. */ static struct page *ecryptfs_get1page(struct file *file, int index) { struct page *page; struct dentry *dentry; struct inode *inode; struct address_space *mapping; dentry = file->f_path.dentry; inode = dentry->d_inode; mapping = inode->i_mapping; page = read_cache_page(mapping, index, (filler_t *)mapping->a_ops->readpage, (void *)file); if (IS_ERR(page)) goto out; wait_on_page_locked(page); out: return page; } static int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros); /** * ecryptfs_fill_zeros * @file: The ecryptfs file * @new_length: The new length of the data in the underlying file; * everything between the prior end of the file and the * new end of the file will be filled with zero's. * new_length must be greater than current length * * Function for handling lseek-ing past the end of the file. * * This function does not support shrinking, only growing a file. * * Returns zero on success; non-zero otherwise. */ int ecryptfs_fill_zeros(struct file *file, loff_t new_length) { int rc = 0; struct dentry *dentry = file->f_path.dentry; struct inode *inode = dentry->d_inode; pgoff_t old_end_page_index = 0; pgoff_t index = old_end_page_index; int old_end_pos_in_page = -1; pgoff_t new_end_page_index; int new_end_pos_in_page; loff_t cur_length = i_size_read(inode); if (cur_length != 0) { index = old_end_page_index = ((cur_length - 1) >> PAGE_CACHE_SHIFT); old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK); } new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT); new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK); ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; " "old_end_pos_in_page = [%d]; " "new_end_page_index = [0x%.16x]; " "new_end_pos_in_page = [%d]\n", old_end_page_index, old_end_pos_in_page, new_end_page_index, new_end_pos_in_page); if (old_end_page_index == new_end_page_index) { /* Start and end are in the same page; we just need to * set a portion of the existing page to zero's */ rc = write_zeros(file, index, (old_end_pos_in_page + 1), (new_end_pos_in_page - old_end_pos_in_page)); if (rc) ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " "index=[0x%.16x], " "old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - new_end_pos_in_page" "=[%d]" ")=[d]) returned [%d]\n", file, index, old_end_pos_in_page, new_end_pos_in_page, (PAGE_CACHE_SIZE - new_end_pos_in_page), rc); goto out; } /* Fill the remainder of the previous last page with zeros */ rc = write_zeros(file, index, (old_end_pos_in_page + 1), ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page)); if (rc) { ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " "index=[0x%.16x], old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) " "returned [%d]\n", file, index, old_end_pos_in_page, (PAGE_CACHE_SIZE - old_end_pos_in_page), rc); goto out; } index++; while (index < new_end_page_index) { /* Fill all intermediate pages with zeros */ rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE); if (rc) { ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], " "index=[0x%.16x], " "old_end_pos_in_page=[d], " "(PAGE_CACHE_SIZE - new_end_pos_in_page" "=[%d]" ")=[d]) returned [%d]\n", file, index, old_end_pos_in_page, new_end_pos_in_page, (PAGE_CACHE_SIZE - new_end_pos_in_page), rc); goto out; } index++; } /* Fill the portion at the beginning of the last new page with * zero's */ rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1)); if (rc) { ecryptfs_printk(KERN_ERR, "write_zeros(file=" "[%p], index=[0x%.16x], 0, " "new_end_pos_in_page=[%d]" "returned [%d]\n", file, index, new_end_pos_in_page, rc); goto out; } out: return rc; } /** * ecryptfs_writepage * @page: Page that is locked before this call is made * * Returns zero on success; non-zero otherwise */ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc) { struct ecryptfs_page_crypt_context ctx; int rc; ctx.page = page; ctx.mode = ECRYPTFS_WRITEPAGE_MODE; ctx.param.wbc = wbc; rc = ecryptfs_encrypt_page(&ctx); if (rc) { ecryptfs_printk(KERN_WARNING, "Error encrypting " "page (upper index [0x%.16x])\n", page->index); ClearPageUptodate(page); goto out; } SetPageUptodate(page); unlock_page(page); out: return rc; } /** * Reads the data from the lower file file at index lower_page_index * and copies that data into page. * * @param page Page to fill * @param lower_page_index Index of the page in the lower file to get */ int ecryptfs_do_readpage(struct file *file, struct page *page, pgoff_t lower_page_index) { int rc; struct dentry *dentry; struct file *lower_file; struct dentry *lower_dentry; struct inode *inode; struct inode *lower_inode; char *page_data; struct page *lower_page = NULL; char *lower_page_data; const struct address_space_operations *lower_a_ops; dentry = file->f_path.dentry; lower_file = ecryptfs_file_to_lower(file); lower_dentry = ecryptfs_dentry_to_lower(dentry); inode = dentry->d_inode; lower_inode = ecryptfs_inode_to_lower(inode); lower_a_ops = lower_inode->i_mapping->a_ops; lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index, (filler_t *)lower_a_ops->readpage, (void *)lower_file); if (IS_ERR(lower_page)) { rc = PTR_ERR(lower_page); lower_page = NULL; ecryptfs_printk(KERN_ERR, "Error reading from page cache\n"); goto out; } wait_on_page_locked(lower_page); page_data = (char *)kmap(page); if (!page_data) { rc = -ENOMEM; ecryptfs_printk(KERN_ERR, "Error mapping page\n"); goto out; } lower_page_data = (char *)kmap(lower_page); if (!lower_page_data) { rc = -ENOMEM; ecryptfs_printk(KERN_ERR, "Error mapping page\n"); kunmap(page); goto out; } memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE); kunmap(lower_page); kunmap(page); rc = 0; out: if (likely(lower_page)) page_cache_release(lower_page); if (rc == 0) SetPageUptodate(page); else ClearPageUptodate(page); return rc; } /** * ecryptfs_readpage * @file: This is an ecryptfs file * @page: ecryptfs associated page to stick the read data into * * Read in a page, decrypting if necessary. * * Returns zero on success; non-zero on error. */ static int ecryptfs_readpage(struct file *file, struct page *page) { int rc = 0; struct ecryptfs_crypt_stat *crypt_stat; BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode)); crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode) ->crypt_stat; if (!crypt_stat || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED) || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) { ecryptfs_printk(KERN_DEBUG, "Passing through unencrypted page\n"); rc = ecryptfs_do_readpage(file, page, page->index); if (rc) { ecryptfs_printk(KERN_ERR, "Error reading page; rc = " "[%d]\n", rc); goto out; } } else { rc = ecryptfs_decrypt_page(file, page); if (rc) { ecryptfs_printk(KERN_ERR, "Error decrypting page; " "rc = [%d]\n", rc); goto out; } } SetPageUptodate(page); out: if (rc) ClearPageUptodate(page); ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n", page->index); unlock_page(page); return rc; } static int fill_zeros_to_end_of_page(struct page *page, unsigned int to) { struct inode *inode = page->mapping->host; int end_byte_in_page; int rc = 0; char *page_virt; if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) { end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE; if (to > end_byte_in_page) end_byte_in_page = to; page_virt = kmap(page); if (!page_virt) { rc = -ENOMEM; ecryptfs_printk(KERN_WARNING, "Could not map page\n"); goto out; } memset((page_virt + end_byte_in_page), 0, (PAGE_CACHE_SIZE - end_byte_in_page)); kunmap(page); } out: return rc; } static int ecryptfs_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to) { int rc = 0; kmap(page); if (from == 0 && to == PAGE_CACHE_SIZE) goto out; /* If we are writing a full page, it will be up to date. */ if (!PageUptodate(page)) rc = ecryptfs_do_readpage(file, page, page->index); out: return rc; } int ecryptfs_grab_and_map_lower_page(struct page **lower_page, char **lower_virt, struct inode *lower_inode, unsigned long lower_page_index) { int rc = 0; (*lower_page) = grab_cache_page(lower_inode->i_mapping, lower_page_index); if (!(*lower_page)) { ecryptfs_printk(KERN_ERR, "grab_cache_page for " "lower_page_index = [0x%.16x] failed\n", lower_page_index); rc = -EINVAL; goto out; } if (lower_virt) (*lower_virt) = kmap((*lower_page)); else kmap((*lower_page)); out: return rc; } int ecryptfs_writepage_and_release_lower_page(struct page *lower_page, struct inode *lower_inode, struct writeback_control *wbc) { int rc = 0; rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc); if (rc) { ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); " "rc = [%d]\n", rc); goto out; } lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME; page_cache_release(lower_page); out: return rc; } static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page) { kunmap(lower_page); ecryptfs_printk(KERN_DEBUG, "Unlocking lower page with index = " "[0x%.16x]\n", lower_page->index); unlock_page(lower_page); page_cache_release(lower_page); } /** * ecryptfs_write_inode_size_to_header * * Writes the lower file size to the first 8 bytes of the header. * * Returns zero on success; non-zero on error. */ int ecryptfs_write_inode_size_to_header(struct file *lower_file, struct inode *lower_inode, struct inode *inode) { int rc = 0; struct page *header_page; char *header_virt; const struct address_space_operations *lower_a_ops; u64 file_size; rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt, lower_inode, 0); if (rc) { ecryptfs_printk(KERN_ERR, "grab_cache_page for header page " "failed\n"); goto out; } lower_a_ops = lower_inode->i_mapping->a_ops; rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8); file_size = (u64)i_size_read(inode); ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size); file_size = cpu_to_be64(file_size); memcpy(header_virt, &file_size, sizeof(u64)); rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8); if (rc < 0) ecryptfs_printk(KERN_ERR, "Error commiting header page " "write\n"); ecryptfs_unmap_and_release_lower_page(header_page); lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME; mark_inode_dirty_sync(inode); out: return rc; } int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode, struct file *lower_file, unsigned long lower_page_index, int byte_offset, int region_bytes) { int rc = 0; rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, lower_inode, lower_page_index); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting to grab and map " "lower page with index [0x%.16x]\n", lower_page_index); goto out; } rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file, (*lower_page), byte_offset, region_bytes); if (rc) { ecryptfs_printk(KERN_ERR, "prepare_write for " "lower_page_index = [0x%.16x] failed; rc = " "[%d]\n", lower_page_index, rc); } out: if (rc && (*lower_page)) { ecryptfs_unmap_and_release_lower_page(*lower_page); (*lower_page) = NULL; } return rc; } /** * ecryptfs_commit_lower_page * * Returns zero on success; non-zero on error */ int ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode, struct file *lower_file, int byte_offset, int region_size) { int rc = 0; rc = lower_inode->i_mapping->a_ops->commit_write( lower_file, lower_page, byte_offset, region_size); if (rc < 0) { ecryptfs_printk(KERN_ERR, "Error committing write; rc = [%d]\n", rc); } else rc = 0; ecryptfs_unmap_and_release_lower_page(lower_page); return rc; } /** * ecryptfs_copy_page_to_lower * * Used for plaintext pass-through; no page index interpolation * required. */ int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode, struct file *lower_file) { int rc = 0; struct page *lower_page; rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file, page->index, 0, PAGE_CACHE_SIZE); if (rc) { ecryptfs_printk(KERN_ERR, "Error attempting to get page " "at index [0x%.16x]\n", page->index); goto out; } /* TODO: aops */ memcpy((char *)page_address(lower_page), page_address(page), PAGE_CACHE_SIZE); rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file, 0, PAGE_CACHE_SIZE); if (rc) ecryptfs_printk(KERN_ERR, "Error attempting to commit page " "at index [0x%.16x]\n", page->index); out: return rc; } static int process_new_file(struct ecryptfs_crypt_stat *crypt_stat, struct file *file, struct inode *inode) { struct page *header_page; const struct address_space_operations *lower_a_ops; struct inode *lower_inode; struct file *lower_file; char *header_virt; int rc = 0; int current_header_page = 0; int header_pages; int more_header_data_to_be_written = 1; lower_inode = ecryptfs_inode_to_lower(inode); lower_file = ecryptfs_file_to_lower(file); lower_a_ops = lower_inode->i_mapping->a_ops; header_pages = ((crypt_stat->header_extent_size * crypt_stat->num_header_extents_at_front) / PAGE_CACHE_SIZE); BUG_ON(header_pages < 1); while (current_header_page < header_pages) { rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt, lower_inode, current_header_page); if (rc) { ecryptfs_printk(KERN_ERR, "grab_cache_page for " "header page [%d] failed; rc = [%d]\n", current_header_page, rc); goto out; } rc = lower_a_ops->prepare_write(lower_file, header_page, 0, PAGE_CACHE_SIZE); if (rc) { ecryptfs_printk(KERN_ERR, "Error preparing to write " "header page out; rc = [%d]\n", rc); goto out; } memset(header_virt, 0, PAGE_CACHE_SIZE); if (more_header_data_to_be_written) { rc = ecryptfs_write_headers_virt(header_virt, crypt_stat, file->f_dentry); if (rc) { ecryptfs_printk(KERN_WARNING, "Error " "generating header; rc = " "[%d]\n", rc); rc = -EIO; memset(header_virt, 0, PAGE_CACHE_SIZE); ecryptfs_unmap_and_release_lower_page( header_page); goto out; } if (current_header_page == 0) memset(header_virt, 0, 8); more_header_data_to_be_written = 0; } rc = lower_a_ops->commit_write(lower_file, header_page, 0, PAGE_CACHE_SIZE); ecryptfs_unmap_and_release_lower_page(header_page); if (rc < 0) { ecryptfs_printk(KERN_ERR, "Error commiting header page write; " "rc = [%d]\n", rc); break; } current_header_page++; } if (rc >= 0) { rc = 0; ecryptfs_printk(KERN_DEBUG, "lower_inode->i_blocks = " "[0x%.16x]\n", lower_inode->i_blocks); i_size_write(inode, 0); lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME; mark_inode_dirty_sync(inode); } ecryptfs_printk(KERN_DEBUG, "Clearing ECRYPTFS_NEW_FILE flag in " "crypt_stat at memory location [%p]\n", crypt_stat); ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE); out: return rc; } /** * ecryptfs_commit_write * @file: The eCryptfs file object * @page: The eCryptfs page * @from: Ignored (we rotate the page IV on each write) * @to: Ignored * * This is where we encrypt the data and pass the encrypted data to * the lower filesystem. In OpenPGP-compatible mode, we operate on * entire underlying packets. */ static int ecryptfs_commit_write(struct file *file, struct page *page, unsigned from, unsigned to) { struct ecryptfs_page_crypt_context ctx; loff_t pos; struct inode *inode; struct inode *lower_inode; struct file *lower_file; struct ecryptfs_crypt_stat *crypt_stat; int rc; inode = page->mapping->host; lower_inode = ecryptfs_inode_to_lower(inode); lower_file = ecryptfs_file_to_lower(file); mutex_lock(&lower_inode->i_mutex); crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode) ->crypt_stat; if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) { ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in " "crypt_stat at memory location [%p]\n", crypt_stat); rc = process_new_file(crypt_stat, file, inode); if (rc) { ecryptfs_printk(KERN_ERR, "Error processing new " "file; rc = [%d]\n", rc); goto out; } } else ecryptfs_printk(KERN_DEBUG, "Not a new file\n"); ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page" "(page w/ index = [0x%.16x], to = [%d])\n", page->index, to); rc = fill_zeros_to_end_of_page(page, to); if (rc) { ecryptfs_printk(KERN_WARNING, "Error attempting to fill " "zeros in page with index = [0x%.16x]\n", page->index); goto out; } ctx.page = page; ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE; ctx.param.lower_file = lower_file; rc = ecryptfs_encrypt_page(&ctx); if (rc) { ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper " "index [0x%.16x])\n", page->index); goto out; } rc = 0; inode->i_blocks = lower_inode->i_blocks; pos = (page->index << PAGE_CACHE_SHIFT) + to; if (pos > i_size_read(inode)) { i_size_write(inode, pos); ecryptfs_printk(KERN_DEBUG, "Expanded file size to " "[0x%.16x]\n", i_size_read(inode)); } ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode); lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME; mark_inode_dirty_sync(inode); out: kunmap(page); /* mapped in prior call (prepare_write) */ if (rc < 0) ClearPageUptodate(page); else SetPageUptodate(page); mutex_unlock(&lower_inode->i_mutex); return rc; } /** * write_zeros * @file: The ecryptfs file * @index: The index in which we are writing * @start: The position after the last block of data * @num_zeros: The number of zeros to write * * Write a specified number of zero's to a page. * * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE */ static int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros) { int rc = 0; struct page *tmp_page; tmp_page = ecryptfs_get1page(file, index); if (IS_ERR(tmp_page)) { ecryptfs_printk(KERN_ERR, "Error getting page at index " "[0x%.16x]\n", index); rc = PTR_ERR(tmp_page); goto out; } kmap(tmp_page); rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros); if (rc) { ecryptfs_printk(KERN_ERR, "Error preparing to write zero's " "to remainder of page at index [0x%.16x]\n", index); kunmap(tmp_page); page_cache_release(tmp_page); goto out; } memset(((char *)page_address(tmp_page) + start), 0, num_zeros); rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros); if (rc < 0) { ecryptfs_printk(KERN_ERR, "Error attempting to write zero's " "to remainder of page at index [0x%.16x]\n", index); kunmap(tmp_page); page_cache_release(tmp_page); goto out; } rc = 0; kunmap(tmp_page); page_cache_release(tmp_page); out: return rc; } static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block) { int rc = 0; struct inode *inode; struct inode *lower_inode; inode = (struct inode *)mapping->host; lower_inode = ecryptfs_inode_to_lower(inode); if (lower_inode->i_mapping->a_ops->bmap) rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping, block); return rc; } static void ecryptfs_sync_page(struct page *page) { struct inode *inode; struct inode *lower_inode; struct page *lower_page; inode = page->mapping->host; lower_inode = ecryptfs_inode_to_lower(inode); /* NOTE: Recently swapped with grab_cache_page(), since * sync_page() just makes sure that pending I/O gets done. */ lower_page = find_lock_page(lower_inode->i_mapping, page->index); if (!lower_page) { ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n"); return; } lower_page->mapping->a_ops->sync_page(lower_page); ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n", lower_page->index); unlock_page(lower_page); page_cache_release(lower_page); } struct address_space_operations ecryptfs_aops = { .writepage = ecryptfs_writepage, .readpage = ecryptfs_readpage, .prepare_write = ecryptfs_prepare_write, .commit_write = ecryptfs_commit_write, .bmap = ecryptfs_bmap, .sync_page = ecryptfs_sync_page, };