mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
555 lines
15 KiB
555 lines
15 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* |
|
* 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 <[email protected]> |
|
*/ |
|
|
|
#include <linux/pagemap.h> |
|
#include <linux/writeback.h> |
|
#include <linux/page-flags.h> |
|
#include <linux/mount.h> |
|
#include <linux/file.h> |
|
#include <linux/scatterlist.h> |
|
#include <linux/slab.h> |
|
#include <linux/xattr.h> |
|
#include <asm/unaligned.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 inode *inode, loff_t index) |
|
{ |
|
struct page *page = read_mapping_page(inode->i_mapping, index, NULL); |
|
if (!IS_ERR(page)) |
|
lock_page(page); |
|
return page; |
|
} |
|
|
|
/** |
|
* ecryptfs_writepage |
|
* @page: Page that is locked before this call is made |
|
* @wbc: Write-back control structure |
|
* |
|
* Returns zero on success; non-zero otherwise |
|
* |
|
* 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_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%.16lx])\n", page->index); |
|
ClearPageUptodate(page); |
|
goto out; |
|
} |
|
SetPageUptodate(page); |
|
out: |
|
unlock_page(page); |
|
return rc; |
|
} |
|
|
|
static void strip_xattr_flag(char *page_virt, |
|
struct ecryptfs_crypt_stat *crypt_stat) |
|
{ |
|
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) { |
|
size_t written; |
|
|
|
crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR; |
|
ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat, |
|
&written); |
|
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR; |
|
} |
|
} |
|
|
|
/* |
|
* 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 |
|
*/ |
|
|
|
/** |
|
* 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_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->metadata_size / 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); |
|
memset(page_virt, 0, PAGE_SIZE); |
|
/* TODO: Support more than one header extent */ |
|
if (view_extent_num == 0) { |
|
size_t written; |
|
|
|
rc = ecryptfs_read_xattr_region( |
|
page_virt, page->mapping->host); |
|
strip_xattr_flag(page_virt + 16, crypt_stat); |
|
ecryptfs_write_header_metadata(page_virt + 20, |
|
crypt_stat, |
|
&written); |
|
} |
|
kunmap_atomic(page_virt); |
|
flush_dcache_page(page); |
|
if (rc) { |
|
printk(KERN_ERR "%s: Error reading xattr " |
|
"region; rc = [%d]\n", __func__, rc); |
|
goto out; |
|
} |
|
} else { |
|
/* This is an encrypted data extent */ |
|
loff_t lower_offset = |
|
((view_extent_num * crypt_stat->extent_size) |
|
- crypt_stat->metadata_size); |
|
|
|
rc = ecryptfs_read_lower_page_segment( |
|
page, (lower_offset >> PAGE_SHIFT), |
|
(lower_offset & ~PAGE_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", __func__, |
|
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(page->mapping->host)->crypt_stat; |
|
int rc = 0; |
|
|
|
if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { |
|
rc = ecryptfs_read_lower_page_segment(page, page->index, 0, |
|
PAGE_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", __func__, rc); |
|
goto out; |
|
} |
|
|
|
} else { |
|
rc = ecryptfs_read_lower_page_segment( |
|
page, page->index, 0, PAGE_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%.16lx]\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_SIZE) != page->index) |
|
goto out; |
|
end_byte_in_page = i_size_read(inode) % PAGE_SIZE; |
|
if (to > end_byte_in_page) |
|
end_byte_in_page = to; |
|
zero_user_segment(page, end_byte_in_page, PAGE_SIZE); |
|
out: |
|
return 0; |
|
} |
|
|
|
/** |
|
* ecryptfs_write_begin |
|
* @file: The eCryptfs file |
|
* @mapping: The eCryptfs object |
|
* @pos: The file offset at which to start writing |
|
* @len: Length of the write |
|
* @flags: Various flags |
|
* @pagep: Pointer to return the page |
|
* @fsdata: Pointer to return fs data (unused) |
|
* |
|
* This function must zero any hole we create |
|
* |
|
* Returns zero on success; non-zero otherwise |
|
*/ |
|
static int ecryptfs_write_begin(struct file *file, |
|
struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned flags, |
|
struct page **pagep, void **fsdata) |
|
{ |
|
pgoff_t index = pos >> PAGE_SHIFT; |
|
struct page *page; |
|
loff_t prev_page_end_size; |
|
int rc = 0; |
|
|
|
page = grab_cache_page_write_begin(mapping, index, flags); |
|
if (!page) |
|
return -ENOMEM; |
|
*pagep = page; |
|
|
|
prev_page_end_size = ((loff_t)index << PAGE_SHIFT); |
|
if (!PageUptodate(page)) { |
|
struct ecryptfs_crypt_stat *crypt_stat = |
|
&ecryptfs_inode_to_private(mapping->host)->crypt_stat; |
|
|
|
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { |
|
rc = ecryptfs_read_lower_page_segment( |
|
page, index, 0, PAGE_SIZE, mapping->host); |
|
if (rc) { |
|
printk(KERN_ERR "%s: Error attempting to read " |
|
"lower page segment; rc = [%d]\n", |
|
__func__, 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", __func__, rc); |
|
ClearPageUptodate(page); |
|
goto out; |
|
} |
|
SetPageUptodate(page); |
|
} else { |
|
rc = ecryptfs_read_lower_page_segment( |
|
page, index, 0, PAGE_SIZE, |
|
mapping->host); |
|
if (rc) { |
|
printk(KERN_ERR "%s: Error reading " |
|
"page; rc = [%d]\n", |
|
__func__, rc); |
|
ClearPageUptodate(page); |
|
goto out; |
|
} |
|
SetPageUptodate(page); |
|
} |
|
} else { |
|
if (prev_page_end_size |
|
>= i_size_read(page->mapping->host)) { |
|
zero_user(page, 0, PAGE_SIZE); |
|
SetPageUptodate(page); |
|
} else if (len < PAGE_SIZE) { |
|
rc = ecryptfs_decrypt_page(page); |
|
if (rc) { |
|
printk(KERN_ERR "%s: Error decrypting " |
|
"page at index [%ld]; " |
|
"rc = [%d]\n", |
|
__func__, page->index, rc); |
|
ClearPageUptodate(page); |
|
goto out; |
|
} |
|
SetPageUptodate(page); |
|
} |
|
} |
|
} |
|
/* If creating a page or more of holes, zero them out via truncate. |
|
* Note, this will increase i_size. */ |
|
if (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", __func__, |
|
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(mapping->host) == prev_page_end_size) |
|
&& (pos != 0)) |
|
zero_user(page, 0, PAGE_SIZE); |
|
out: |
|
if (unlikely(rc)) { |
|
unlock_page(page); |
|
put_page(page); |
|
*pagep = NULL; |
|
} |
|
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) |
|
{ |
|
char *file_size_virt; |
|
int rc; |
|
|
|
file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL); |
|
if (!file_size_virt) { |
|
rc = -ENOMEM; |
|
goto out; |
|
} |
|
put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt); |
|
rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0, |
|
sizeof(u64)); |
|
kfree(file_size_virt); |
|
if (rc < 0) |
|
printk(KERN_ERR "%s: Error writing file size to header; " |
|
"rc = [%d]\n", __func__, rc); |
|
else |
|
rc = 0; |
|
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_path.dentry; |
|
struct inode *lower_inode = d_inode(lower_dentry); |
|
int rc; |
|
|
|
if (!(lower_inode->i_opflags & IOP_XATTR)) { |
|
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) { |
|
rc = -ENOMEM; |
|
goto out; |
|
} |
|
inode_lock(lower_inode); |
|
size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME, |
|
xattr_virt, PAGE_SIZE); |
|
if (size < 0) |
|
size = 8; |
|
put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt); |
|
rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode, |
|
ECRYPTFS_XATTR_NAME, xattr_virt, size, 0); |
|
inode_unlock(lower_inode); |
|
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; |
|
BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)); |
|
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_write_end |
|
* @file: The eCryptfs file object |
|
* @mapping: The eCryptfs object |
|
* @pos: The file position |
|
* @len: The length of the data (unused) |
|
* @copied: The amount of data copied |
|
* @page: The eCryptfs page |
|
* @fsdata: The fsdata (unused) |
|
*/ |
|
static int ecryptfs_write_end(struct file *file, |
|
struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned copied, |
|
struct page *page, void *fsdata) |
|
{ |
|
pgoff_t index = pos >> PAGE_SHIFT; |
|
unsigned from = pos & (PAGE_SIZE - 1); |
|
unsigned to = from + copied; |
|
struct inode *ecryptfs_inode = mapping->host; |
|
struct ecryptfs_crypt_stat *crypt_stat = |
|
&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; |
|
int rc; |
|
|
|
ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page" |
|
"(page w/ index = [0x%.16lx], to = [%d])\n", index, to); |
|
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) { |
|
rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0, |
|
to); |
|
if (!rc) { |
|
rc = copied; |
|
fsstack_copy_inode_size(ecryptfs_inode, |
|
ecryptfs_inode_to_lower(ecryptfs_inode)); |
|
} |
|
goto out; |
|
} |
|
if (!PageUptodate(page)) { |
|
if (copied < PAGE_SIZE) { |
|
rc = 0; |
|
goto out; |
|
} |
|
SetPageUptodate(page); |
|
} |
|
/* 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%.16lx]\n", index); |
|
goto out; |
|
} |
|
rc = ecryptfs_encrypt_page(page); |
|
if (rc) { |
|
ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper " |
|
"index [0x%.16lx])\n", index); |
|
goto out; |
|
} |
|
if (pos + copied > i_size_read(ecryptfs_inode)) { |
|
i_size_write(ecryptfs_inode, pos + copied); |
|
ecryptfs_printk(KERN_DEBUG, "Expanded file size to " |
|
"[0x%.16llx]\n", |
|
(unsigned long long)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); |
|
else |
|
rc = copied; |
|
out: |
|
unlock_page(page); |
|
put_page(page); |
|
return rc; |
|
} |
|
|
|
static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block) |
|
{ |
|
struct inode *lower_inode = ecryptfs_inode_to_lower(mapping->host); |
|
int ret = bmap(lower_inode, &block); |
|
|
|
if (ret) |
|
return 0; |
|
return block; |
|
} |
|
|
|
#include <linux/buffer_head.h> |
|
|
|
const struct address_space_operations ecryptfs_aops = { |
|
/* |
|
* XXX: This is pretty broken for multiple reasons: ecryptfs does not |
|
* actually use buffer_heads, and ecryptfs will crash without |
|
* CONFIG_BLOCK. But it matches the behavior before the default for |
|
* address_space_operations without the ->set_page_dirty method was |
|
* cleaned up, so this is the best we can do without maintainer |
|
* feedback. |
|
*/ |
|
#ifdef CONFIG_BLOCK |
|
.set_page_dirty = __set_page_dirty_buffers, |
|
#endif |
|
.writepage = ecryptfs_writepage, |
|
.readpage = ecryptfs_readpage, |
|
.write_begin = ecryptfs_write_begin, |
|
.write_end = ecryptfs_write_end, |
|
.bmap = ecryptfs_bmap, |
|
};
|
|
|