1da0102a1SMichael Halcrow /** 2da0102a1SMichael Halcrow * eCryptfs: Linux filesystem encryption layer 3da0102a1SMichael Halcrow * 4da0102a1SMichael Halcrow * Copyright (C) 2007 International Business Machines Corp. 5da0102a1SMichael Halcrow * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> 6da0102a1SMichael Halcrow * 7da0102a1SMichael Halcrow * This program is free software; you can redistribute it and/or 8da0102a1SMichael Halcrow * modify it under the terms of the GNU General Public License as 9da0102a1SMichael Halcrow * published by the Free Software Foundation; either version 2 of the 10da0102a1SMichael Halcrow * License, or (at your option) any later version. 11da0102a1SMichael Halcrow * 12da0102a1SMichael Halcrow * This program is distributed in the hope that it will be useful, but 13da0102a1SMichael Halcrow * WITHOUT ANY WARRANTY; without even the implied warranty of 14da0102a1SMichael Halcrow * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15da0102a1SMichael Halcrow * General Public License for more details. 16da0102a1SMichael Halcrow * 17da0102a1SMichael Halcrow * You should have received a copy of the GNU General Public License 18da0102a1SMichael Halcrow * along with this program; if not, write to the Free Software 19da0102a1SMichael Halcrow * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 20da0102a1SMichael Halcrow * 02111-1307, USA. 21da0102a1SMichael Halcrow */ 22da0102a1SMichael Halcrow 23da0102a1SMichael Halcrow #include <linux/fs.h> 24da0102a1SMichael Halcrow #include <linux/pagemap.h> 25da0102a1SMichael Halcrow #include "ecryptfs_kernel.h" 26da0102a1SMichael Halcrow 27da0102a1SMichael Halcrow /** 28da0102a1SMichael Halcrow * ecryptfs_write_lower 29da0102a1SMichael Halcrow * @ecryptfs_inode: The eCryptfs inode 30da0102a1SMichael Halcrow * @data: Data to write 31da0102a1SMichael Halcrow * @offset: Byte offset in the lower file to which to write the data 32da0102a1SMichael Halcrow * @size: Number of bytes from @data to write at @offset in the lower 33da0102a1SMichael Halcrow * file 34da0102a1SMichael Halcrow * 35da0102a1SMichael Halcrow * Write data to the lower file. 36da0102a1SMichael Halcrow * 3796a7b9c2STyler Hicks * Returns bytes written on success; less than zero on error 38da0102a1SMichael Halcrow */ 39da0102a1SMichael Halcrow int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, 40da0102a1SMichael Halcrow loff_t offset, size_t size) 41da0102a1SMichael Halcrow { 42f61500e0STyler Hicks struct file *lower_file; 4396a7b9c2STyler Hicks ssize_t rc; 44da0102a1SMichael Halcrow 45f61500e0STyler Hicks lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; 46f61500e0STyler Hicks if (!lower_file) 47f61500e0STyler Hicks return -EIO; 487bb307e8SAl Viro rc = kernel_write(lower_file, data, size, offset); 49da0102a1SMichael Halcrow mark_inode_dirty_sync(ecryptfs_inode); 50da0102a1SMichael Halcrow return rc; 51da0102a1SMichael Halcrow } 52da0102a1SMichael Halcrow 53da0102a1SMichael Halcrow /** 54da0102a1SMichael Halcrow * ecryptfs_write_lower_page_segment 55da0102a1SMichael Halcrow * @ecryptfs_inode: The eCryptfs inode 56da0102a1SMichael Halcrow * @page_for_lower: The page containing the data to be written to the 57da0102a1SMichael Halcrow * lower file 58da0102a1SMichael Halcrow * @offset_in_page: The offset in the @page_for_lower from which to 59da0102a1SMichael Halcrow * start writing the data 60da0102a1SMichael Halcrow * @size: The amount of data from @page_for_lower to write to the 61da0102a1SMichael Halcrow * lower file 62da0102a1SMichael Halcrow * 63da0102a1SMichael Halcrow * Determines the byte offset in the file for the given page and 64da0102a1SMichael Halcrow * offset within the page, maps the page, and makes the call to write 65da0102a1SMichael Halcrow * the contents of @page_for_lower to the lower inode. 66da0102a1SMichael Halcrow * 67da0102a1SMichael Halcrow * Returns zero on success; non-zero otherwise 68da0102a1SMichael Halcrow */ 69da0102a1SMichael Halcrow int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, 70da0102a1SMichael Halcrow struct page *page_for_lower, 71da0102a1SMichael Halcrow size_t offset_in_page, size_t size) 72da0102a1SMichael Halcrow { 73da0102a1SMichael Halcrow char *virt; 74da0102a1SMichael Halcrow loff_t offset; 75da0102a1SMichael Halcrow int rc; 76da0102a1SMichael Halcrow 77*09cbfeafSKirill A. Shutemov offset = ((((loff_t)page_for_lower->index) << PAGE_SHIFT) 78d6a13c17SMichael Halcrow + offset_in_page); 79da0102a1SMichael Halcrow virt = kmap(page_for_lower); 80da0102a1SMichael Halcrow rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); 8196a7b9c2STyler Hicks if (rc > 0) 8296a7b9c2STyler Hicks rc = 0; 83da0102a1SMichael Halcrow kunmap(page_for_lower); 84da0102a1SMichael Halcrow return rc; 85da0102a1SMichael Halcrow } 86da0102a1SMichael Halcrow 87da0102a1SMichael Halcrow /** 88da0102a1SMichael Halcrow * ecryptfs_write 8948c1e44aSAl Viro * @ecryptfs_inode: The eCryptfs file into which to write 90da0102a1SMichael Halcrow * @data: Virtual address where data to write is located 91da0102a1SMichael Halcrow * @offset: Offset in the eCryptfs file at which to begin writing the 92da0102a1SMichael Halcrow * data from @data 93da0102a1SMichael Halcrow * @size: The number of bytes to write from @data 94da0102a1SMichael Halcrow * 95da0102a1SMichael Halcrow * Write an arbitrary amount of data to an arbitrary location in the 96da0102a1SMichael Halcrow * eCryptfs inode page cache. This is done on a page-by-page, and then 97da0102a1SMichael Halcrow * by an extent-by-extent, basis; individual extents are encrypted and 98da0102a1SMichael Halcrow * written to the lower page cache (via VFS writes). This function 99da0102a1SMichael Halcrow * takes care of all the address translation to locations in the lower 100da0102a1SMichael Halcrow * filesystem; it also handles truncate events, writing out zeros 101da0102a1SMichael Halcrow * where necessary. 102da0102a1SMichael Halcrow * 103da0102a1SMichael Halcrow * Returns zero on success; non-zero otherwise 104da0102a1SMichael Halcrow */ 10548c1e44aSAl Viro int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, 106da0102a1SMichael Halcrow size_t size) 107da0102a1SMichael Halcrow { 108da0102a1SMichael Halcrow struct page *ecryptfs_page; 10913a791b4STyler Hicks struct ecryptfs_crypt_stat *crypt_stat; 110da0102a1SMichael Halcrow char *ecryptfs_page_virt; 11113a791b4STyler Hicks loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); 112da0102a1SMichael Halcrow loff_t data_offset = 0; 113da0102a1SMichael Halcrow loff_t pos; 114da0102a1SMichael Halcrow int rc = 0; 115da0102a1SMichael Halcrow 11613a791b4STyler Hicks crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; 1177a3f595cSEric Sandeen /* 1187a3f595cSEric Sandeen * if we are writing beyond current size, then start pos 1197a3f595cSEric Sandeen * at the current size - we'll fill in zeros from there. 1207a3f595cSEric Sandeen */ 121da0102a1SMichael Halcrow if (offset > ecryptfs_file_size) 122da0102a1SMichael Halcrow pos = ecryptfs_file_size; 123da0102a1SMichael Halcrow else 124da0102a1SMichael Halcrow pos = offset; 125da0102a1SMichael Halcrow while (pos < (offset + size)) { 126*09cbfeafSKirill A. Shutemov pgoff_t ecryptfs_page_idx = (pos >> PAGE_SHIFT); 127*09cbfeafSKirill A. Shutemov size_t start_offset_in_page = (pos & ~PAGE_MASK); 128*09cbfeafSKirill A. Shutemov size_t num_bytes = (PAGE_SIZE - start_offset_in_page); 129684a3ff7SLi Wang loff_t total_remaining_bytes = ((offset + size) - pos); 130da0102a1SMichael Halcrow 1315e6f0d76STyler Hicks if (fatal_signal_pending(current)) { 1325e6f0d76STyler Hicks rc = -EINTR; 1335e6f0d76STyler Hicks break; 1345e6f0d76STyler Hicks } 1355e6f0d76STyler Hicks 136da0102a1SMichael Halcrow if (num_bytes > total_remaining_bytes) 137da0102a1SMichael Halcrow num_bytes = total_remaining_bytes; 138da0102a1SMichael Halcrow if (pos < offset) { 1397a3f595cSEric Sandeen /* remaining zeros to write, up to destination offset */ 140684a3ff7SLi Wang loff_t total_remaining_zeros = (offset - pos); 141da0102a1SMichael Halcrow 142da0102a1SMichael Halcrow if (num_bytes > total_remaining_zeros) 143da0102a1SMichael Halcrow num_bytes = total_remaining_zeros; 144da0102a1SMichael Halcrow } 14502bd9799SAl Viro ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, 146da0102a1SMichael Halcrow ecryptfs_page_idx); 147da0102a1SMichael Halcrow if (IS_ERR(ecryptfs_page)) { 148da0102a1SMichael Halcrow rc = PTR_ERR(ecryptfs_page); 149da0102a1SMichael Halcrow printk(KERN_ERR "%s: Error getting page at " 150da0102a1SMichael Halcrow "index [%ld] from eCryptfs inode " 15118d1dbf1SHarvey Harrison "mapping; rc = [%d]\n", __func__, 152da0102a1SMichael Halcrow ecryptfs_page_idx, rc); 153da0102a1SMichael Halcrow goto out; 154da0102a1SMichael Halcrow } 155465c9343SCong Wang ecryptfs_page_virt = kmap_atomic(ecryptfs_page); 1567a3f595cSEric Sandeen 1577a3f595cSEric Sandeen /* 1587a3f595cSEric Sandeen * pos: where we're now writing, offset: where the request was 1597a3f595cSEric Sandeen * If current pos is before request, we are filling zeros 1607a3f595cSEric Sandeen * If we are at or beyond request, we are writing the *data* 1617a3f595cSEric Sandeen * If we're in a fresh page beyond eof, zero it in either case 1627a3f595cSEric Sandeen */ 1637a3f595cSEric Sandeen if (pos < offset || !start_offset_in_page) { 1647a3f595cSEric Sandeen /* We are extending past the previous end of the file. 1657a3f595cSEric Sandeen * Fill in zero values to the end of the page */ 1667a3f595cSEric Sandeen memset(((char *)ecryptfs_page_virt 1677a3f595cSEric Sandeen + start_offset_in_page), 0, 168*09cbfeafSKirill A. Shutemov PAGE_SIZE - start_offset_in_page); 1697a3f595cSEric Sandeen } 1707a3f595cSEric Sandeen 1717a3f595cSEric Sandeen /* pos >= offset, we are now writing the data request */ 172da0102a1SMichael Halcrow if (pos >= offset) { 173da0102a1SMichael Halcrow memcpy(((char *)ecryptfs_page_virt 174da0102a1SMichael Halcrow + start_offset_in_page), 175da0102a1SMichael Halcrow (data + data_offset), num_bytes); 176da0102a1SMichael Halcrow data_offset += num_bytes; 177da0102a1SMichael Halcrow } 178465c9343SCong Wang kunmap_atomic(ecryptfs_page_virt); 179da0102a1SMichael Halcrow flush_dcache_page(ecryptfs_page); 18016a72c45SMichael Halcrow SetPageUptodate(ecryptfs_page); 18116a72c45SMichael Halcrow unlock_page(ecryptfs_page); 18213a791b4STyler Hicks if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) 1830216f7f7SMichael Halcrow rc = ecryptfs_encrypt_page(ecryptfs_page); 18413a791b4STyler Hicks else 18513a791b4STyler Hicks rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, 18613a791b4STyler Hicks ecryptfs_page, 18713a791b4STyler Hicks start_offset_in_page, 18813a791b4STyler Hicks data_offset); 189*09cbfeafSKirill A. Shutemov put_page(ecryptfs_page); 190da0102a1SMichael Halcrow if (rc) { 191da0102a1SMichael Halcrow printk(KERN_ERR "%s: Error encrypting " 19218d1dbf1SHarvey Harrison "page; rc = [%d]\n", __func__, rc); 193da0102a1SMichael Halcrow goto out; 194da0102a1SMichael Halcrow } 195da0102a1SMichael Halcrow pos += num_bytes; 196da0102a1SMichael Halcrow } 1975e6f0d76STyler Hicks if (pos > ecryptfs_file_size) { 1985e6f0d76STyler Hicks i_size_write(ecryptfs_inode, pos); 19913a791b4STyler Hicks if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { 2005e6f0d76STyler Hicks int rc2; 2015e6f0d76STyler Hicks 2025e6f0d76STyler Hicks rc2 = ecryptfs_write_inode_size_to_metadata( 20313a791b4STyler Hicks ecryptfs_inode); 2045e6f0d76STyler Hicks if (rc2) { 205da0102a1SMichael Halcrow printk(KERN_ERR "Problem with " 206da0102a1SMichael Halcrow "ecryptfs_write_inode_size_to_metadata; " 2075e6f0d76STyler Hicks "rc = [%d]\n", rc2); 2085e6f0d76STyler Hicks if (!rc) 2095e6f0d76STyler Hicks rc = rc2; 210da0102a1SMichael Halcrow goto out; 211da0102a1SMichael Halcrow } 212da0102a1SMichael Halcrow } 21313a791b4STyler Hicks } 214da0102a1SMichael Halcrow out: 215da0102a1SMichael Halcrow return rc; 216da0102a1SMichael Halcrow } 217da0102a1SMichael Halcrow 218da0102a1SMichael Halcrow /** 219da0102a1SMichael Halcrow * ecryptfs_read_lower 220da0102a1SMichael Halcrow * @data: The read data is stored here by this function 221da0102a1SMichael Halcrow * @offset: Byte offset in the lower file from which to read the data 222da0102a1SMichael Halcrow * @size: Number of bytes to read from @offset of the lower file and 223da0102a1SMichael Halcrow * store into @data 224da0102a1SMichael Halcrow * @ecryptfs_inode: The eCryptfs inode 225da0102a1SMichael Halcrow * 226da0102a1SMichael Halcrow * Read @size bytes of data at byte offset @offset from the lower 227da0102a1SMichael Halcrow * inode into memory location @data. 228da0102a1SMichael Halcrow * 22996a7b9c2STyler Hicks * Returns bytes read on success; 0 on EOF; less than zero on error 230da0102a1SMichael Halcrow */ 231da0102a1SMichael Halcrow int ecryptfs_read_lower(char *data, loff_t offset, size_t size, 232da0102a1SMichael Halcrow struct inode *ecryptfs_inode) 233da0102a1SMichael Halcrow { 234f61500e0STyler Hicks struct file *lower_file; 235f61500e0STyler Hicks lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; 236f61500e0STyler Hicks if (!lower_file) 237f61500e0STyler Hicks return -EIO; 23839dfe6c6SAl Viro return kernel_read(lower_file, offset, data, size); 239da0102a1SMichael Halcrow } 240da0102a1SMichael Halcrow 241da0102a1SMichael Halcrow /** 242da0102a1SMichael Halcrow * ecryptfs_read_lower_page_segment 243da0102a1SMichael Halcrow * @page_for_ecryptfs: The page into which data for eCryptfs will be 244da0102a1SMichael Halcrow * written 245da0102a1SMichael Halcrow * @offset_in_page: Offset in @page_for_ecryptfs from which to start 246da0102a1SMichael Halcrow * writing 247da0102a1SMichael Halcrow * @size: The number of bytes to write into @page_for_ecryptfs 248da0102a1SMichael Halcrow * @ecryptfs_inode: The eCryptfs inode 249da0102a1SMichael Halcrow * 250da0102a1SMichael Halcrow * Determines the byte offset in the file for the given page and 251da0102a1SMichael Halcrow * offset within the page, maps the page, and makes the call to read 252da0102a1SMichael Halcrow * the contents of @page_for_ecryptfs from the lower inode. 253da0102a1SMichael Halcrow * 254da0102a1SMichael Halcrow * Returns zero on success; non-zero otherwise 255da0102a1SMichael Halcrow */ 256da0102a1SMichael Halcrow int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, 257da0102a1SMichael Halcrow pgoff_t page_index, 258da0102a1SMichael Halcrow size_t offset_in_page, size_t size, 259da0102a1SMichael Halcrow struct inode *ecryptfs_inode) 260da0102a1SMichael Halcrow { 261da0102a1SMichael Halcrow char *virt; 262da0102a1SMichael Halcrow loff_t offset; 263da0102a1SMichael Halcrow int rc; 264da0102a1SMichael Halcrow 265*09cbfeafSKirill A. Shutemov offset = ((((loff_t)page_index) << PAGE_SHIFT) + offset_in_page); 266da0102a1SMichael Halcrow virt = kmap(page_for_ecryptfs); 267da0102a1SMichael Halcrow rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); 26896a7b9c2STyler Hicks if (rc > 0) 26996a7b9c2STyler Hicks rc = 0; 270da0102a1SMichael Halcrow kunmap(page_for_ecryptfs); 27116a72c45SMichael Halcrow flush_dcache_page(page_for_ecryptfs); 272da0102a1SMichael Halcrow return rc; 273da0102a1SMichael Halcrow } 274