Revision 6632fa8fcabacd75329bd2ea78cba5c43754639a authored by Masahiro Yamada on 24 April 2020, 16:15:02 UTC, committed by Masahiro Yamada on 12 May 2020, 04:28:32 UTC
'make ARCH=hexagon clean' emits an error message as follows: $ make ARCH=hexagon clean gcc: error: unrecognized command line option '-G0' You can suppress it by setting the correct CROSS_COMPILE=, but we should not require any compiler for cleaning. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Brian Cain <bcain@codeaurora.org>
1 parent 7e49afc
verity.c
// SPDX-License-Identifier: GPL-2.0
/*
* fs/f2fs/verity.c: fs-verity support for f2fs
*
* Copyright 2019 Google LLC
*/
/*
* Implementation of fsverity_operations for f2fs.
*
* Like ext4, f2fs stores the verity metadata (Merkle tree and
* fsverity_descriptor) past the end of the file, starting at the first 64K
* boundary beyond i_size. This approach works because (a) verity files are
* readonly, and (b) pages fully beyond i_size aren't visible to userspace but
* can be read/written internally by f2fs with only some relatively small
* changes to f2fs. Extended attributes cannot be used because (a) f2fs limits
* the total size of an inode's xattr entries to 4096 bytes, which wouldn't be
* enough for even a single Merkle tree block, and (b) f2fs encryption doesn't
* encrypt xattrs, yet the verity metadata *must* be encrypted when the file is
* because it contains hashes of the plaintext data.
*
* Using a 64K boundary rather than a 4K one keeps things ready for
* architectures with 64K pages, and it doesn't necessarily waste space on-disk
* since there can be a hole between i_size and the start of the Merkle tree.
*/
#include <linux/f2fs_fs.h>
#include "f2fs.h"
#include "xattr.h"
static inline loff_t f2fs_verity_metadata_pos(const struct inode *inode)
{
return round_up(inode->i_size, 65536);
}
/*
* Read some verity metadata from the inode. __vfs_read() can't be used because
* we need to read beyond i_size.
*/
static int pagecache_read(struct inode *inode, void *buf, size_t count,
loff_t pos)
{
while (count) {
size_t n = min_t(size_t, count,
PAGE_SIZE - offset_in_page(pos));
struct page *page;
void *addr;
page = read_mapping_page(inode->i_mapping, pos >> PAGE_SHIFT,
NULL);
if (IS_ERR(page))
return PTR_ERR(page);
addr = kmap_atomic(page);
memcpy(buf, addr + offset_in_page(pos), n);
kunmap_atomic(addr);
put_page(page);
buf += n;
pos += n;
count -= n;
}
return 0;
}
/*
* Write some verity metadata to the inode for FS_IOC_ENABLE_VERITY.
* kernel_write() can't be used because the file descriptor is readonly.
*/
static int pagecache_write(struct inode *inode, const void *buf, size_t count,
loff_t pos)
{
if (pos + count > inode->i_sb->s_maxbytes)
return -EFBIG;
while (count) {
size_t n = min_t(size_t, count,
PAGE_SIZE - offset_in_page(pos));
struct page *page;
void *fsdata;
void *addr;
int res;
res = pagecache_write_begin(NULL, inode->i_mapping, pos, n, 0,
&page, &fsdata);
if (res)
return res;
addr = kmap_atomic(page);
memcpy(addr + offset_in_page(pos), buf, n);
kunmap_atomic(addr);
res = pagecache_write_end(NULL, inode->i_mapping, pos, n, n,
page, fsdata);
if (res < 0)
return res;
if (res != n)
return -EIO;
buf += n;
pos += n;
count -= n;
}
return 0;
}
/*
* Format of f2fs verity xattr. This points to the location of the verity
* descriptor within the file data rather than containing it directly because
* the verity descriptor *must* be encrypted when f2fs encryption is used. But,
* f2fs encryption does not encrypt xattrs.
*/
struct fsverity_descriptor_location {
__le32 version;
__le32 size;
__le64 pos;
};
static int f2fs_begin_enable_verity(struct file *filp)
{
struct inode *inode = file_inode(filp);
int err;
if (f2fs_verity_in_progress(inode))
return -EBUSY;
if (f2fs_is_atomic_file(inode) || f2fs_is_volatile_file(inode))
return -EOPNOTSUPP;
/*
* Since the file was opened readonly, we have to initialize the quotas
* here and not rely on ->open() doing it. This must be done before
* evicting the inline data.
*/
err = dquot_initialize(inode);
if (err)
return err;
err = f2fs_convert_inline_inode(inode);
if (err)
return err;
set_inode_flag(inode, FI_VERITY_IN_PROGRESS);
return 0;
}
static int f2fs_end_enable_verity(struct file *filp, const void *desc,
size_t desc_size, u64 merkle_tree_size)
{
struct inode *inode = file_inode(filp);
u64 desc_pos = f2fs_verity_metadata_pos(inode) + merkle_tree_size;
struct fsverity_descriptor_location dloc = {
.version = cpu_to_le32(1),
.size = cpu_to_le32(desc_size),
.pos = cpu_to_le64(desc_pos),
};
int err = 0;
if (desc != NULL) {
/* Succeeded; write the verity descriptor. */
err = pagecache_write(inode, desc, desc_size, desc_pos);
/* Write all pages before clearing FI_VERITY_IN_PROGRESS. */
if (!err)
err = filemap_write_and_wait(inode->i_mapping);
}
/* If we failed, truncate anything we wrote past i_size. */
if (desc == NULL || err)
f2fs_truncate(inode);
clear_inode_flag(inode, FI_VERITY_IN_PROGRESS);
if (desc != NULL && !err) {
err = f2fs_setxattr(inode, F2FS_XATTR_INDEX_VERITY,
F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc),
NULL, XATTR_CREATE);
if (!err) {
file_set_verity(inode);
f2fs_set_inode_flags(inode);
f2fs_mark_inode_dirty_sync(inode, true);
}
}
return err;
}
static int f2fs_get_verity_descriptor(struct inode *inode, void *buf,
size_t buf_size)
{
struct fsverity_descriptor_location dloc;
int res;
u32 size;
u64 pos;
/* Get the descriptor location */
res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_VERITY,
F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc), NULL);
if (res < 0 && res != -ERANGE)
return res;
if (res != sizeof(dloc) || dloc.version != cpu_to_le32(1)) {
f2fs_warn(F2FS_I_SB(inode), "unknown verity xattr format");
return -EINVAL;
}
size = le32_to_cpu(dloc.size);
pos = le64_to_cpu(dloc.pos);
/* Get the descriptor */
if (pos + size < pos || pos + size > inode->i_sb->s_maxbytes ||
pos < f2fs_verity_metadata_pos(inode) || size > INT_MAX) {
f2fs_warn(F2FS_I_SB(inode), "invalid verity xattr");
return -EFSCORRUPTED;
}
if (buf_size) {
if (size > buf_size)
return -ERANGE;
res = pagecache_read(inode, buf, size, pos);
if (res)
return res;
}
return size;
}
/*
* Prefetch some pages from the file's Merkle tree.
*
* This is basically a stripped-down version of __do_page_cache_readahead()
* which works on pages past i_size.
*/
static void f2fs_merkle_tree_readahead(struct address_space *mapping,
pgoff_t start_index, unsigned long count)
{
LIST_HEAD(pages);
unsigned int nr_pages = 0;
struct page *page;
pgoff_t index;
struct blk_plug plug;
for (index = start_index; index < start_index + count; index++) {
page = xa_load(&mapping->i_pages, index);
if (!page || xa_is_value(page)) {
page = __page_cache_alloc(readahead_gfp_mask(mapping));
if (!page)
break;
page->index = index;
list_add(&page->lru, &pages);
nr_pages++;
}
}
blk_start_plug(&plug);
f2fs_mpage_readpages(mapping, &pages, NULL, nr_pages, true);
blk_finish_plug(&plug);
}
static struct page *f2fs_read_merkle_tree_page(struct inode *inode,
pgoff_t index,
unsigned long num_ra_pages)
{
struct page *page;
index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT;
page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED);
if (!page || !PageUptodate(page)) {
if (page)
put_page(page);
else if (num_ra_pages > 1)
f2fs_merkle_tree_readahead(inode->i_mapping, index,
num_ra_pages);
page = read_mapping_page(inode->i_mapping, index, NULL);
}
return page;
}
static int f2fs_write_merkle_tree_block(struct inode *inode, const void *buf,
u64 index, int log_blocksize)
{
loff_t pos = f2fs_verity_metadata_pos(inode) + (index << log_blocksize);
return pagecache_write(inode, buf, 1 << log_blocksize, pos);
}
const struct fsverity_operations f2fs_verityops = {
.begin_enable_verity = f2fs_begin_enable_verity,
.end_enable_verity = f2fs_end_enable_verity,
.get_verity_descriptor = f2fs_get_verity_descriptor,
.read_merkle_tree_page = f2fs_read_merkle_tree_page,
.write_merkle_tree_block = f2fs_write_merkle_tree_block,
};
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