android_kernel_xiaomi_sm8350/fs/ecryptfs/mmap.c

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/**
* 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) 2004-2007 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"
/**
* ecryptfs_get_locked_page
*
* Get one page from cache or lower f/s, return error otherwise.
*
* Returns locked and up-to-date page (if ok), with increased
* refcnt.
*/
struct page *ecryptfs_get_locked_page(struct file *file, loff_t index)
{
struct dentry *dentry;
struct inode *inode;
struct address_space *mapping;
struct page *page;
dentry = file->f_path.dentry;
inode = dentry->d_inode;
mapping = inode->i_mapping;
page = read_mapping_page(mapping, index, (void *)file);
if (!IS_ERR(page))
lock_page(page);
return page;
}
/**
* 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)
{
int rc;
rc = ecryptfs_encrypt_page(page);
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;
}
/**
* 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
*/
static void set_header_info(char *page_virt,
struct ecryptfs_crypt_stat *crypt_stat)
{
size_t written;
size_t save_num_header_bytes_at_front =
crypt_stat->num_header_bytes_at_front;
crypt_stat->num_header_bytes_at_front =
ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
crypt_stat->num_header_bytes_at_front =
save_num_header_bytes_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 = ((((loff_t)page->index)
* num_extents_per_page)
+ extent_num_in_page);
size_t num_header_extents_at_front =
(crypt_stat->num_header_bytes_at_front
/ crypt_stat->extent_size);
if (view_extent_num < 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) {
printk(KERN_ERR "%s: Error reading xattr "
"region; rc = [%d]\n", __FUNCTION__, rc);
goto out;
}
} else {
/* This is an encrypted data extent */
loff_t lower_offset =
((view_extent_num * crypt_stat->extent_size)
- crypt_stat->num_header_bytes_at_front);
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: An eCryptfs file
* @page: Page from eCryptfs inode mapping into which to stick the read data
*
* 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)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
int rc = 0;
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_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) {
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_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);
goto out;
}
}
} else {
rc = ecryptfs_decrypt_page(page);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error decrypting page; "
"rc = [%d]\n", rc);
goto out;
}
}
out:
if (rc)
ClearPageUptodate(page);
else
SetPageUptodate(page);
ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
page->index);
unlock_page(page);
return rc;
}
/**
* Called with lower inode mutex held.
*/
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;
if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
goto out;
end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
if (to > end_byte_in_page)
end_byte_in_page = to;
Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user Simplify page cache zeroing of segments of pages through 3 functions zero_user_segments(page, start1, end1, start2, end2) Zeros two segments of the page. It takes the position where to start and end the zeroing which avoids length calculations and makes code clearer. zero_user_segment(page, start, end) Same for a single segment. zero_user(page, start, length) Length variant for the case where we know the length. We remove the zero_user_page macro. Issues: 1. Its a macro. Inline functions are preferable. 2. The KM_USER0 macro is only defined for HIGHMEM. Having to treat this special case everywhere makes the code needlessly complex. The parameter for zeroing is always KM_USER0 except in one single case that we open code. Avoiding KM_USER0 makes a lot of code not having to be dealing with the special casing for HIGHMEM anymore. Dealing with kmap is only necessary for HIGHMEM configurations. In those configurations we use KM_USER0 like we do for a series of other functions defined in highmem.h. Since KM_USER0 is depends on HIGHMEM the existing zero_user_page function could not be a macro. zero_user_* functions introduced here can be be inline because that constant is not used when these functions are called. Also extract the flushing of the caches to be outside of the kmap. [akpm@linux-foundation.org: fix nfs and ntfs build] [akpm@linux-foundation.org: fix ntfs build some more] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 01:28:29 -05:00
zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
out:
return 0;
}
/**
* ecryptfs_prepare_write
* @file: The eCryptfs file
* @page: The eCryptfs page
* @from: The start byte from which we will write
* @to: The end byte to which we will write
*
* This function must zero any hole we create
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
loff_t prev_page_end_size;
int rc = 0;
if (!PageUptodate(page)) {
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(
file->f_path.dentry->d_inode)->crypt_stat;
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
|| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
rc = ecryptfs_read_lower_page_segment(
page, page->index, 0, PAGE_CACHE_SIZE,
page->mapping->host);
if (rc) {
printk(KERN_ERR "%s: Error attemping to read "
"lower page segment; rc = [%d]\n",
__FUNCTION__, rc);
ClearPageUptodate(page);
goto out;
} else
SetPageUptodate(page);
} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
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);
ClearPageUptodate(page);
goto out;
}
SetPageUptodate(page);
} else {
rc = ecryptfs_read_lower_page_segment(
page, page->index, 0, PAGE_CACHE_SIZE,
page->mapping->host);
if (rc) {
printk(KERN_ERR "%s: Error reading "
"page; rc = [%d]\n",
__FUNCTION__, rc);
ClearPageUptodate(page);
goto out;
}
SetPageUptodate(page);
}
} else {
rc = ecryptfs_decrypt_page(page);
if (rc) {
printk(KERN_ERR "%s: Error decrypting page "
"at index [%ld]; rc = [%d]\n",
__FUNCTION__, page->index, rc);
ClearPageUptodate(page);
goto out;
}
SetPageUptodate(page);
}
}
prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
/* If creating a page or more of holes, zero them out via truncate.
* Note, this will increase i_size. */
if (page->index != 0) {
if (prev_page_end_size > i_size_read(page->mapping->host)) {
rc = ecryptfs_truncate(file->f_path.dentry,
prev_page_end_size);
if (rc) {
printk(KERN_ERR "%s: Error on attempt to "
"truncate to (higher) offset [%lld];"
" rc = [%d]\n", __FUNCTION__,
prev_page_end_size, rc);
goto out;
}
}
}
/* Writing to a new page, and creating a small hole from start
* of page? Zero it out. */
if ((i_size_read(page->mapping->host) == prev_page_end_size)
&& (from != 0))
Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user Simplify page cache zeroing of segments of pages through 3 functions zero_user_segments(page, start1, end1, start2, end2) Zeros two segments of the page. It takes the position where to start and end the zeroing which avoids length calculations and makes code clearer. zero_user_segment(page, start, end) Same for a single segment. zero_user(page, start, length) Length variant for the case where we know the length. We remove the zero_user_page macro. Issues: 1. Its a macro. Inline functions are preferable. 2. The KM_USER0 macro is only defined for HIGHMEM. Having to treat this special case everywhere makes the code needlessly complex. The parameter for zeroing is always KM_USER0 except in one single case that we open code. Avoiding KM_USER0 makes a lot of code not having to be dealing with the special casing for HIGHMEM anymore. Dealing with kmap is only necessary for HIGHMEM configurations. In those configurations we use KM_USER0 like we do for a series of other functions defined in highmem.h. Since KM_USER0 is depends on HIGHMEM the existing zero_user_page function could not be a macro. zero_user_* functions introduced here can be be inline because that constant is not used when these functions are called. Also extract the flushing of the caches to be outside of the kmap. [akpm@linux-foundation.org: fix nfs and ntfs build] [akpm@linux-foundation.org: fix ntfs build some more] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: <linux-ext4@vger.kernel.org> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Cc: Steven French <sfrench@us.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 01:28:29 -05:00
zero_user(page, 0, PAGE_CACHE_SIZE);
out:
return rc;
}
/**
* 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.
*/
static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
{
u64 file_size;
char *file_size_virt;
int rc;
file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
if (!file_size_virt) {
rc = -ENOMEM;
goto out;
}
file_size = (u64)i_size_read(ecryptfs_inode);
file_size = cpu_to_be64(file_size);
memcpy(file_size_virt, &file_size, sizeof(u64));
rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
sizeof(u64));
kfree(file_size_virt);
if (rc)
printk(KERN_ERR "%s: Error writing file size to header; "
"rc = [%d]\n", __FUNCTION__, rc);
out:
return rc;
}
struct kmem_cache *ecryptfs_xattr_cache;
static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
{
ssize_t size;
void *xattr_virt;
struct dentry *lower_dentry =
ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
struct inode *lower_inode = lower_dentry->d_inode;
u64 file_size;
int rc;
if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
printk(KERN_WARNING
"No support for setting xattr in lower filesystem\n");
rc = -ENOSYS;
goto out;
}
xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
if (!xattr_virt) {
printk(KERN_ERR "Out of memory whilst attempting to write "
"inode size to xattr\n");
rc = -ENOMEM;
goto out;
}
mutex_lock(&lower_inode->i_mutex);
size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
xattr_virt, PAGE_CACHE_SIZE);
if (size < 0)
size = 8;
file_size = (u64)i_size_read(ecryptfs_inode);
file_size = cpu_to_be64(file_size);
memcpy(xattr_virt, &file_size, sizeof(u64));
rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
xattr_virt, size, 0);
mutex_unlock(&lower_inode->i_mutex);
if (rc)
printk(KERN_ERR "Error whilst attempting to write inode size "
"to lower file xattr; rc = [%d]\n", rc);
kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
out:
return rc;
}
int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat;
crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
else
return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
}
/**
* 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)
{
loff_t pos;
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;
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);
crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
} 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);
/* 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 "
"zeros in page with index = [0x%.16x]\n",
page->index);
goto out;
}
rc = ecryptfs_encrypt_page(page);
if (rc) {
ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
"index [0x%.16x])\n", page->index);
goto out;
}
pos = (((loff_t)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(ecryptfs_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);
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;
}
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,
};