From bf12be1cc851cface331b0e74713a6bb1cb046b0 Mon Sep 17 00:00:00 2001 From: Michael Halcrow Date: Tue, 16 Oct 2007 01:28:11 -0700 Subject: [PATCH] eCryptfs: convert mmap functions to use persistent file Convert readpage, prepare_write, and commit_write to use read_write.c routines. Remove sync_page; I cannot think of a good reason for implementing that in eCryptfs. Signed-off-by: Michael Halcrow Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ecryptfs/mmap.c | 199 +++++++++++++++++++++++---------------------- 1 file changed, 103 insertions(+), 96 deletions(-) diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index 60e635eddc..9bc707df3b 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -266,10 +266,79 @@ static void set_header_info(char *page_virt, save_num_header_extents_at_front; } +/** + * ecryptfs_copy_up_encrypted_with_header + * @page: Sort of a ``virtual'' representation of the encrypted lower + * file. The actual lower file does not have the metadata in + * the header. This is locked. + * @crypt_stat: The eCryptfs inode's cryptographic context + * + * The ``view'' is the version of the file that userspace winds up + * seeing, with the header information inserted. + */ +static int +ecryptfs_copy_up_encrypted_with_header(struct page *page, + struct ecryptfs_crypt_stat *crypt_stat) +{ + loff_t extent_num_in_page = 0; + loff_t num_extents_per_page = (PAGE_CACHE_SIZE + / crypt_stat->extent_size); + int rc = 0; + + while (extent_num_in_page < num_extents_per_page) { + loff_t view_extent_num = ((page->index * num_extents_per_page) + + extent_num_in_page); + + if (view_extent_num < crypt_stat->num_header_extents_at_front) { + /* This is a header extent */ + char *page_virt; + + page_virt = kmap_atomic(page, KM_USER0); + memset(page_virt, 0, PAGE_CACHE_SIZE); + /* TODO: Support more than one header extent */ + if (view_extent_num == 0) { + rc = ecryptfs_read_xattr_region( + page_virt, page->mapping->host); + set_header_info(page_virt, crypt_stat); + } + kunmap_atomic(page_virt, KM_USER0); + flush_dcache_page(page); + if (rc) { + ClearPageUptodate(page); + printk(KERN_ERR "%s: Error reading xattr " + "region; rc = [%d]\n", __FUNCTION__, rc); + goto out; + } + SetPageUptodate(page); + } else { + /* This is an encrypted data extent */ + loff_t lower_offset = + ((view_extent_num - + crypt_stat->num_header_extents_at_front) + * crypt_stat->extent_size); + + rc = ecryptfs_read_lower_page_segment( + page, (lower_offset >> PAGE_CACHE_SHIFT), + (lower_offset & ~PAGE_CACHE_MASK), + crypt_stat->extent_size, page->mapping->host); + if (rc) { + printk(KERN_ERR "%s: Error attempting to read " + "extent at offset [%lld] in the lower " + "file; rc = [%d]\n", __FUNCTION__, + lower_offset, rc); + goto out; + } + } + extent_num_in_page++; + } +out: + return rc; +} + /** * ecryptfs_readpage - * @file: This is an ecryptfs file - * @page: ecryptfs associated page to stick the read data into + * @file: An eCryptfs file + * @page: Page from eCryptfs inode mapping into which to stick the read data * * Read in a page, decrypting if necessary. * @@ -277,59 +346,35 @@ static void set_header_info(char *page_virt, */ static int ecryptfs_readpage(struct file *file, struct page *page) { + struct ecryptfs_crypt_stat *crypt_stat = + &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat; 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 || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED) || (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; - } + rc = ecryptfs_read_lower_page_segment(page, page->index, 0, + PAGE_CACHE_SIZE, + page->mapping->host); } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) { if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) { - int num_pages_in_header_region = - (crypt_stat->extent_size - / PAGE_CACHE_SIZE); - - if (page->index < num_pages_in_header_region) { - char *page_virt; - - page_virt = kmap_atomic(page, KM_USER0); - memset(page_virt, 0, PAGE_CACHE_SIZE); - if (page->index == 0) { - rc = ecryptfs_read_xattr_region( - page_virt, page->mapping->host); - set_header_info(page_virt, crypt_stat); - } - kunmap_atomic(page_virt, KM_USER0); - flush_dcache_page(page); - if (rc) { - printk(KERN_ERR "Error reading xattr " - "region\n"); - goto out; - } - } else { - rc = ecryptfs_do_readpage( - file, page, - (page->index - - num_pages_in_header_region)); - if (rc) { - printk(KERN_ERR "Error reading page; " - "rc = [%d]\n", rc); - goto out; - } + rc = ecryptfs_copy_up_encrypted_with_header(page, + crypt_stat); + if (rc) { + printk(KERN_ERR "%s: Error attempting to copy " + "the encrypted content from the lower " + "file whilst inserting the metadata " + "from the xattr into the header; rc = " + "[%d]\n", __FUNCTION__, rc); + goto out; } + } else { - rc = ecryptfs_do_readpage(file, page, page->index); + rc = ecryptfs_read_lower_page_segment( + page, page->index, 0, PAGE_CACHE_SIZE, + page->mapping->host); if (rc) { printk(KERN_ERR "Error reading page; rc = " "[%d]\n", rc); @@ -344,10 +389,7 @@ static int ecryptfs_readpage(struct file *file, struct page *page) 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); @@ -403,9 +445,12 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page, 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); + rc = ecryptfs_read_lower_page_segment(page, page->index, 0, + PAGE_CACHE_SIZE, + page->mapping->host); if (page->index != 0) { - loff_t end_of_prev_pg_pos = page_offset(page) - 1; + loff_t end_of_prev_pg_pos = + (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1); if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) { rc = ecryptfs_truncate(file->f_path.dentry, @@ -633,18 +678,11 @@ static int ecryptfs_commit_write(struct file *file, struct page *page, unsigned from, unsigned to) { loff_t pos; - struct inode *inode; - struct inode *lower_inode; - struct file *lower_file; - struct ecryptfs_crypt_stat *crypt_stat; + struct inode *ecryptfs_inode = page->mapping->host; + struct ecryptfs_crypt_stat *crypt_stat = + &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->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 (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); @@ -654,6 +692,7 @@ static int ecryptfs_commit_write(struct file *file, struct page *page, ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page" "(page w/ index = [0x%.16x], to = [%d])\n", page->index, to); + /* Fills in zeros if 'to' goes beyond inode size */ rc = fill_zeros_to_end_of_page(page, to); if (rc) { ecryptfs_printk(KERN_WARNING, "Error attempting to fill " @@ -667,25 +706,17 @@ static int ecryptfs_commit_write(struct file *file, struct page *page, "index [0x%.16x])\n", page->index); goto out; } - inode->i_blocks = lower_inode->i_blocks; - pos = page_offset(page) + to; - if (pos > i_size_read(inode)) { - i_size_write(inode, pos); + pos = (page->index << PAGE_CACHE_SHIFT) + to; + if (pos > i_size_read(ecryptfs_inode)) { + i_size_write(ecryptfs_inode, pos); ecryptfs_printk(KERN_DEBUG, "Expanded file size to " - "[0x%.16x]\n", i_size_read(inode)); + "[0x%.16x]\n", i_size_read(ecryptfs_inode)); } - rc = ecryptfs_write_inode_size_to_metadata(inode); + rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode); if (rc) printk(KERN_ERR "Error writing inode size to metadata; " "rc = [%d]\n", rc); - lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME; - mark_inode_dirty_sync(inode); out: - if (rc < 0) - ClearPageUptodate(page); - else - SetPageUptodate(page); - mutex_unlock(&lower_inode->i_mutex); return rc; } @@ -751,34 +782,10 @@ static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t 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; - } - if (lower_page->mapping->a_ops->sync_page) - 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, }; -- 2.39.5