116239Sjkh// SPDX-License-Identifier: GPL-2.0-or-later 24Srgrimes/* 3509Srgrimes * eCryptfs: Linux filesystem encryption layer 450477Speter * 54Srgrimes * Copyright (C) 2007 International Business Machines Corp. 6509Srgrimes * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> 7509Srgrimes */ 84Srgrimes 94Srgrimes#include <linux/fs.h> 104Srgrimes#include <linux/pagemap.h> 114Srgrimes#include <linux/sched/signal.h> 124Srgrimes 134Srgrimes#include "ecryptfs_kernel.h" 144Srgrimes 154Srgrimes/** 164Srgrimes * ecryptfs_write_lower 174Srgrimes * @ecryptfs_inode: The eCryptfs inode 184Srgrimes * @data: Data to write 1930640Speter * @offset: Byte offset in the lower file to which to write the data 2046822Speter * @size: Number of bytes from @data to write at @offset in the lower 2130640Speter * file 2246842Speter * 2346842Speter * Write data to the lower file. 2442368Speter * 2527674Sphk * Returns bytes written on success; less than zero on error 2627674Sphk */ 2752651Smarcelint ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, 282056Swollman loff_t offset, size_t size) 292056Swollman{ 302056Swollman struct file *lower_file; 314Srgrimes ssize_t rc; 322056Swollman 3352651Smarcel lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; 342056Swollman if (!lower_file) 354Srgrimes return -EIO; 364836Sdg rc = kernel_write(lower_file, data, size, &offset); 3718518Sbde mark_inode_dirty_sync(ecryptfs_inode); 387627Snate return rc; 397627Snate} 407627Snate 417627Snate/** 427627Snate * ecryptfs_write_lower_page_segment 437627Snate * @ecryptfs_inode: The eCryptfs inode 4445821Speter * @page_for_lower: The page containing the data to be written to the 45712Swollman * lower file 4638714Sjb * @offset_in_page: The offset in the @page_for_lower from which to 4739537Sbde * start writing the data 4839537Sbde * @size: The amount of data from @page_for_lower to write to the 4939537Sbde * lower file 5039537Sbde * 5148308Speter * Determines the byte offset in the file for the given page and 5239169Sjkh * offset within the page, maps the page, and makes the call to write 5338714Sjb * the contents of @page_for_lower to the lower inode. 5439537Sbde * 5539537Sbde * Returns zero on success; non-zero otherwise 5638714Sjb */ 5738714Sjbint ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, 5838714Sjb struct page *page_for_lower, 5938714Sjb size_t offset_in_page, size_t size) 6038714Sjb{ 6138714Sjb char *virt; 6244670Sdg loff_t offset; 6327065Sbde int rc; 6420395Sbde 6527065Sbde offset = ((((loff_t)page_for_lower->index) << PAGE_SHIFT) 6620395Sbde + offset_in_page); 6720395Sbde virt = kmap_local_page(page_for_lower); 6820395Sbde rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); 6920395Sbde if (rc > 0) 7020395Sbde rc = 0; 714Srgrimes kunmap_local(virt); 7251898Sbde return rc; 7351898Sbde} 7451898Sbde 7551898Sbde/** 764Srgrimes * ecryptfs_write 7737580Sbde * @ecryptfs_inode: The eCryptfs file into which to write 7839537Sbde * @data: Virtual address where data to write is located 7937580Sbde * @offset: Offset in the eCryptfs file at which to begin writing the 802408Sbde * data from @data 8142771Speter * @size: The number of bytes to write from @data 8242771Speter * 8339537Sbde * Write an arbitrary amount of data to an arbitrary location in the 8425985Sjdp * eCryptfs inode page cache. This is done on a page-by-page, and then 8525985Sjdp * by an extent-by-extent, basis; individual extents are encrypted and 8625985Sjdp * written to the lower page cache (via VFS writes). This function 872408Sbde * takes care of all the address translation to locations in the lower 8813031Sbde * filesystem; it also handles truncate events, writing out zeros 895908Sbde * where necessary. 905908Sbde * 915908Sbde * Returns zero on success; non-zero otherwise 9245661Speter */ 9340907Speterint ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, 9425985Sjdp size_t size) 9538714Sjb{ 9625537Sdfr struct page *ecryptfs_page; 9735514Simp struct ecryptfs_crypt_stat *crypt_stat; 9838714Sjb char *ecryptfs_page_virt; 9925537Sdfr loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode); 10045661Speter loff_t data_offset = 0; 10138714Sjb loff_t pos; 10241976Smsmith int rc = 0; 10342450Sjdp 10439818Speter crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; 10539818Speter /* 10635514Simp * if we are writing beyond current size, then start pos 10738714Sjb * at the current size - we'll fill in zeros from there. 10839818Speter */ 10925083Sjdp if (offset > ecryptfs_file_size) 1104Srgrimes pos = ecryptfs_file_size; 1115327Sgibbs else 1125327Sgibbs pos = offset; 1134Srgrimes while (pos < (offset + size)) { 1144Srgrimes pgoff_t ecryptfs_page_idx = (pos >> PAGE_SHIFT); 1154Srgrimes size_t start_offset_in_page = (pos & ~PAGE_MASK); 1164Srgrimes size_t num_bytes = (PAGE_SIZE - start_offset_in_page); 11711918Sdg loff_t total_remaining_bytes = ((offset + size) - pos); 11811918Sdg 11938778Snsouch if (fatal_signal_pending(current)) { 12038778Snsouch rc = -EINTR; 1216802Sgibbs break; 1226802Sgibbs } 12346822Speter 12446822Speter if (num_bytes > total_remaining_bytes) 12546842Speter num_bytes = total_remaining_bytes; 12646842Speter if (pos < offset) { 12746842Speter /* remaining zeros to write, up to destination offset */ 12846842Speter loff_t total_remaining_zeros = (offset - pos); 12946842Speter 13046842Speter if (num_bytes > total_remaining_zeros) 13146842Speter num_bytes = total_remaining_zeros; 13246842Speter } 13346842Speter ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_inode, 13446842Speter ecryptfs_page_idx); 13546842Speter if (IS_ERR(ecryptfs_page)) { 13646842Speter rc = PTR_ERR(ecryptfs_page); 13746842Speter printk(KERN_ERR "%s: Error getting page at " 13848300Sphk "index [%ld] from eCryptfs inode " 13946822Speter "mapping; rc = [%d]\n", __func__, 14046822Speter ecryptfs_page_idx, rc); 14146822Speter goto out; 14246822Speter } 14346822Speter ecryptfs_page_virt = kmap_local_page(ecryptfs_page); 14441592Simp 14544367Sdt /* 14641592Simp * pos: where we're now writing, offset: where the request was 14741592Simp * If current pos is before request, we are filling zeros 1484Srgrimes * If we are at or beyond request, we are writing the *data* 14942450Sjdp * If we're in a fresh page beyond eof, zero it in either case 15045424Sgrog */ 15145424Sgrog if (pos < offset || !start_offset_in_page) { 15237581Sbde /* We are extending past the previous end of the file. 1534Srgrimes * Fill in zero values to the end of the page */ 154715Swollman memset(((char *)ecryptfs_page_virt 15537580Sbde + start_offset_in_page), 0, 156715Swollman PAGE_SIZE - start_offset_in_page); 157715Swollman } 158715Swollman 1594Srgrimes /* pos >= offset, we are now writing the data request */ 16037581Sbde if (pos >= offset) { 1615908Sbde memcpy(((char *)ecryptfs_page_virt 1625908Sbde + start_offset_in_page), 1635908Sbde (data + data_offset), num_bytes); 1644Srgrimes data_offset += num_bytes; 1654Srgrimes } 1664Srgrimes kunmap_local(ecryptfs_page_virt); 1674Srgrimes flush_dcache_page(ecryptfs_page); 1682464Sbde SetPageUptodate(ecryptfs_page); 1692408Sbde unlock_page(ecryptfs_page); 1704Srgrimes if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) 17139818Speter rc = ecryptfs_encrypt_page(ecryptfs_page); 17239818Speter else 17339818Speter rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, 17439818Speter ecryptfs_page, 17542450Sjdp start_offset_in_page, 17639818Speter data_offset); 17742450Sjdp put_page(ecryptfs_page); 17839818Speter if (rc) { 17939818Speter printk(KERN_ERR "%s: Error encrypting " 18039818Speter "page; rc = [%d]\n", __func__, rc); 18143174Speter goto out; 18243174Speter } 18342771Speter pos += num_bytes; 18425083Sjdp } 18525083Sjdp if (pos > ecryptfs_file_size) { 18642771Speter i_size_write(ecryptfs_inode, pos); 18725083Sjdp if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { 18825083Sjdp int rc2; 18942771Speter 19042839Speter rc2 = ecryptfs_write_inode_size_to_metadata( 19125985Sjdp ecryptfs_inode); 1922408Sbde if (rc2) { 1932408Sbde printk(KERN_ERR "Problem with " 1942408Sbde "ecryptfs_write_inode_size_to_metadata; " 195649Snate "rc = [%d]\n", rc2); 1963863Sbde if (!rc) 1974Srgrimes rc = rc2; 19837581Sbde goto out; 19939537Sbde } 2004Srgrimes } 2013863Sbde } 20239169Sjkhout: 2033863Sbde return rc; 20442771Speter} 20525202Speter 2065327Sgibbs/** 20714924Speter * ecryptfs_read_lower 20839537Sbde * @data: The read data is stored here by this function 20939537Sbde * @offset: Byte offset in the lower file from which to read the data 21039537Sbde * @size: Number of bytes to read from @offset of the lower file and 21139537Sbde * store into @data 21214331Speter * @ecryptfs_inode: The eCryptfs inode 21315679Swosch * 2144Srgrimes * Read @size bytes of data at byte offset @offset from the lower 21532924Seivind * inode into memory location @data. 21632924Seivind * 21732924Seivind * Returns bytes read on success; 0 on EOF; less than zero on error 2184Srgrimes */ 21946822Speterint ecryptfs_read_lower(char *data, loff_t offset, size_t size, 2204Srgrimes struct inode *ecryptfs_inode) 22146822Speter{ 2224Srgrimes struct file *lower_file; 2234Srgrimes lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; 2244Srgrimes if (!lower_file) 2254Srgrimes return -EIO; 2264Srgrimes return kernel_read(lower_file, data, size, &offset); 22748440Sjkh} 22848440Sjkh 22948440Sjkh/** 23048440Sjkh * ecryptfs_read_lower_page_segment 2314Srgrimes * @page_for_ecryptfs: The page into which data for eCryptfs will be 23245661Speter * written 23345661Speter * @page_index: Page index in @page_for_ecryptfs from which to start 23445661Speter * writing 23515558Sjoerg * @offset_in_page: Offset in @page_for_ecryptfs from which to start 23615558Sjoerg * writing 23745424Sgrog * @size: The number of bytes to write into @page_for_ecryptfs 23845424Sgrog * @ecryptfs_inode: The eCryptfs inode 23945424Sgrog * 24032924Seivind * Determines the byte offset in the file for the given page and 24131846Sbde * offset within the page, maps the page, and makes the call to read 24245424Sgrog * the contents of @page_for_ecryptfs from the lower inode. 24345424Sgrog * 24446842Speter * Returns zero on success; non-zero otherwise 24546842Speter */ 24630912Sguidoint ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, 24713321Sphk pgoff_t page_index, 24845661Speter size_t offset_in_page, size_t size, 24945661Speter struct inode *ecryptfs_inode) 2502627Swollman{ 25146726Speter char *virt; 25246726Speter loff_t offset; 25346726Speter int rc; 25446726Speter 25537581Sbde offset = ((((loff_t)page_index) << PAGE_SHIFT) + offset_in_page); 25637581Sbde virt = kmap_local_page(page_for_ecryptfs); 2574Srgrimes rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); 25837581Sbde if (rc > 0) 25937581Sbde rc = 0; 26037581Sbde kunmap_local(virt); 261509Srgrimes flush_dcache_page(page_for_ecryptfs); 2624Srgrimes return rc; 2634Srgrimes} 2644Srgrimes