Re: [PATCH 21/29] xfs: add fs-verity support

Darrick J. Wong
2024-03-14T17:06:21Z

On Wed, Mar 13, 2024 at 10:58:03AM -0700, Darrick J. Wong wrote:
> From: Andrey Albershteyn <aalbersh@redhat.com>
>
> Add integration with fs-verity. The XFS store fs-verity metadata in
> the extended file attributes. The metadata consist of verity
> descriptor and Merkle tree blocks.
>
> The descriptor is stored under "vdesc" extended attribute. The
> Merkle tree blocks are stored under binary indexes which are offsets
> into the Merkle tree.
>
> When fs-verity is enabled on an inode, the XFS_IVERITY_CONSTRUCTION
> flag is set meaning that the Merkle tree is being build. The
> initialization ends with storing of verity descriptor and setting
> inode on-disk flag (XFS_DIFLAG2_VERITY).
>
> The verification on read is done in read path of iomap.
>
> Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> [djwong: replace caching implementation with an xarray, other cleanups]
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>

I started writing more of userspace (xfs_db decoding of verity xattrs,
repair/scrub support) so I think I want to make one more change to this.

This change shortens the key structure name, puts a proper namespace on
the merkleoff field to match everything else in the ondisk structs, and
checks it via xfs_ondisk.h.

--D

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 3280fbc3027ec..c2f1b38683646 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -1593,7 +1593,7 @@ xfs_attr_namecheck(

if (flags & XFS_ATTR_VERITY) {
/* Merkle tree pages are stored under u64 indexes */
- if (length == sizeof(struct xfs_fsverity_merkle_key))
+ if (length == sizeof(struct xfs_verity_merkle_key))
return true;

/* Verity descriptor blocks are held in a named attribute. */
diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h
index 6e3b08d4ad74a..e55e437c47ae3 100644
--- a/fs/xfs/libxfs/xfs_da_format.h
+++ b/fs/xfs/libxfs/xfs_da_format.h
@@ -923,10 +923,10 @@ struct xfs_parent_name_rec {
* fs-verity attribute name format
*
* Merkle tree blocks are stored under extended attributes of the inode. The
- * name of the attributes are offsets into merkle tree.
+ * name of the attributes are byte offsets into merkle tree.
*/
-struct xfs_fsverity_merkle_key {
- __be64 merkleoff;
+struct xfs_verity_merkle_key {
+ __be64 bk_merkleoff;
};

/* ondisk xattr name used for the fsverity descriptor */
diff --git a/fs/xfs/libxfs/xfs_ondisk.h b/fs/xfs/libxfs/xfs_ondisk.h
index e4e0e5203ec16..118e993c7d2f3 100644
--- a/fs/xfs/libxfs/xfs_ondisk.h
+++ b/fs/xfs/libxfs/xfs_ondisk.h
@@ -206,8 +206,9 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_VALUE(XFS_DQ_BIGTIME_EXPIRY_MAX << XFS_DQ_BIGTIME_SHIFT,
16299260424LL);

- /* fs-verity descriptor xattr name */
- XFS_CHECK_VALUE(sizeof(XFS_VERITY_DESCRIPTOR_NAME), 6);
+ /* fs-verity xattrs */
+ XFS_CHECK_STRUCT_SIZE(struct xfs_verity_merkle_key, 8);
+ XFS_CHECK_VALUE(sizeof(XFS_VERITY_DESCRIPTOR_NAME), 6);
}

#endif /* __XFS_ONDISK_H */
diff --git a/fs/xfs/xfs_verity.c b/fs/xfs/xfs_verity.c
index 82340c9130494..dca3b68445343 100644
--- a/fs/xfs/xfs_verity.c
+++ b/fs/xfs/xfs_verity.c
@@ -201,20 +201,20 @@ xfs_verity_cache_store(
}

static inline void
-xfs_fsverity_merkle_key_to_disk(
- struct xfs_fsverity_merkle_key *key,
+xfs_verity_merkle_key_to_disk(
+ struct xfs_verity_merkle_key *key,
u64 offset)
{
- key->merkleoff = cpu_to_be64(offset);
+ key->bk_merkleoff = cpu_to_be64(offset);
}

static inline u64
-xfs_fsverity_merkle_key_from_disk(
+xfs_verity_merkle_key_from_disk(
void *attr_name)
{
- struct xfs_fsverity_merkle_key *key = attr_name;
+ struct xfs_verity_merkle_key *key = attr_name;

- return be64_to_cpu(key->merkleoff);
+ return be64_to_cpu(key->bk_merkleoff);
}

static int
@@ -272,7 +272,7 @@ xfs_drop_merkle_tree(
u64 merkle_tree_size,
unsigned int tree_blocksize)
{
- struct xfs_fsverity_merkle_key name;
+ struct xfs_verity_merkle_key name;
int error = 0;
u64 offset = 0;
struct xfs_da_args args = {
@@ -281,7 +281,7 @@ xfs_drop_merkle_tree(
.attr_filter = XFS_ATTR_VERITY,
.op_flags = XFS_DA_OP_REMOVE,
.name = (const uint8_t *)&name,
- .namelen = sizeof(struct xfs_fsverity_merkle_key),
+ .namelen = sizeof(struct xfs_verity_merkle_key),
/* NULL value make xfs_attr_set remove the attr */
.value = NULL,
};
@@ -290,7 +290,7 @@ xfs_drop_merkle_tree(
return 0;

for (offset = 0; offset < merkle_tree_size; offset += tree_blocksize) {
- xfs_fsverity_merkle_key_to_disk(&name, offset);
+ xfs_verity_merkle_key_to_disk(&name, offset);
error = xfs_attr_set(&args);
if (error)
return error;
@@ -372,12 +372,12 @@ xfs_verity_read_merkle(
struct fsverity_blockbuf *block)
{
struct xfs_inode *ip = XFS_I(req->inode);
- struct xfs_fsverity_merkle_key name;
+ struct xfs_verity_merkle_key name;
struct xfs_da_args args = {
.dp = ip,
.attr_filter = XFS_ATTR_VERITY,
.name = (const uint8_t *)&name,
- .namelen = sizeof(struct xfs_fsverity_merkle_key),
+ .namelen = sizeof(struct xfs_verity_merkle_key),
.valuelen = block->size,
};
struct xfs_merkle_blob *mk, *new_mk;
@@ -386,7 +386,7 @@ xfs_verity_read_merkle(

ASSERT(block->offset >> req->log_blocksize <= ULONG_MAX);

- xfs_fsverity_merkle_key_to_disk(&name, block->offset);
+ xfs_verity_merkle_key_to_disk(&name, block->offset);

/* Is the block already cached? */
mk = xfs_verity_cache_load(ip, key);
@@ -399,7 +399,7 @@ xfs_verity_read_merkle(
args.value = new_mk->data;

/* Read the block in from disk and try to store it in the cache. */
- xfs_fsverity_merkle_key_to_disk(&name, block->offset);
+ xfs_verity_merkle_key_to_disk(&name, block->offset);

error = xfs_attr_get(&args);
if (error)
@@ -440,19 +440,18 @@ xfs_verity_write_merkle(
unsigned int size)
{
struct xfs_inode *ip = XFS_I(inode);
- struct xfs_fsverity_merkle_key name;
+ struct xfs_verity_merkle_key name;
struct xfs_da_args args = {
.dp = ip,
.whichfork = XFS_ATTR_FORK,
.attr_filter = XFS_ATTR_VERITY,
- .namelen = sizeof(struct xfs_fsverity_merkle_key),
+ .name = (const uint8_t *)&name,
+ .namelen = sizeof(struct xfs_verity_merkle_key),
.value = (void *)buf,
.valuelen = size,
};

- xfs_fsverity_merkle_key_to_disk(&name, pos);
- args.name = (const uint8_t *)&name.merkleoff;
-
+ xfs_verity_merkle_key_to_disk(&name, pos);
return xfs_attr_set(&args);
}