[PATCH v2 20/23] xfs: add fs-verity support

Andrey Albershteyn
2023-04-04T14:55:53Z

Add integration with fs-verity. The XFS store fs-verity metadata in
the extended attributes. The metadata consist of verity descriptor
and Merkle tree blocks.

The descriptor is stored under "verity_descriptor" extended
attribute. The Merkle tree blocks are stored under binary indexes.

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 iomap. Based on the inode verity
flag the IOMAP_F_READ_VERITY is set in xfs_read_iomap_begin() to let
iomap know that verification is needed.

Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
---
fs/xfs/Makefile | 1 +
fs/xfs/libxfs/xfs_attr.c | 13 +++
fs/xfs/xfs_inode.h | 3 +-
fs/xfs/xfs_iomap.c | 3 +
fs/xfs/xfs_ondisk.h | 4 +
fs/xfs/xfs_super.c | 8 ++
fs/xfs/xfs_verity.c | 214 +++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_verity.h | 19 ++++
8 files changed, 264 insertions(+), 1 deletion(-)
create mode 100644 fs/xfs/xfs_verity.c
create mode 100644 fs/xfs/xfs_verity.h

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 92d88dc3c9f7..76174770d91a 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -130,6 +130,7 @@ xfs-$(CONFIG_XFS_POSIX_ACL) += xfs_acl.o
xfs-$(CONFIG_SYSCTL) += xfs_sysctl.o
xfs-$(CONFIG_COMPAT) += xfs_ioctl32.o
xfs-$(CONFIG_EXPORTFS_BLOCK_OPS) += xfs_pnfs.o
+xfs-$(CONFIG_FS_VERITY) += xfs_verity.o

# notify failure
ifeq ($(CONFIG_MEMORY_FAILURE),y)
diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 298b74245267..39d9038fbeee 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -26,6 +26,7 @@
#include "xfs_trace.h"
#include "xfs_attr_item.h"
#include "xfs_xattr.h"
+#include "xfs_verity.h"

struct kmem_cache *xfs_attr_intent_cache;

@@ -1635,6 +1636,18 @@ xfs_attr_namecheck(
return xfs_verify_pptr(mp, (struct xfs_parent_name_rec *)name);
}

+ if (flags & XFS_ATTR_VERITY) {
+ /* Merkle tree pages are stored under u64 indexes */
+ if (length == sizeof(__be64))
+ return true;
+
+ /* Verity descriptor blocks are held in a named attribute. */
+ if (length == XFS_VERITY_DESCRIPTOR_NAME_LEN)
+ return true;
+
+ return false;
+ }
+
return xfs_str_attr_namecheck(name, length);
}

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 69d21e42c10a..a95f28cb049f 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -324,7 +324,8 @@ static inline bool xfs_inode_has_large_extent_counts(struct xfs_inode *ip)
* inactivation completes, both flags will be cleared and the inode is a
* plain old IRECLAIMABLE inode.
*/
-#define XFS_INACTIVATING (1 << 13)
+#define XFS_INACTIVATING (1 << 13)
+#define XFS_IVERITY_CONSTRUCTION (1 << 14) /* merkle tree construction */

/* All inode state flags related to inode reclaim. */
#define XFS_ALL_IRECLAIM_FLAGS (XFS_IRECLAIMABLE | \
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index e0f3c5d709f6..0adde39f02a5 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -143,6 +143,9 @@ xfs_bmbt_to_iomap(
(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
iomap->flags |= IOMAP_F_DIRTY;

+ if (fsverity_active(VFS_I(ip)))
+ iomap->flags |= IOMAP_F_READ_VERITY;
+
iomap->validity_cookie = sequence_cookie;
iomap->folio_ops = &xfs_iomap_folio_ops;
return 0;
diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
index 9737b5a9f405..7fe88ccda519 100644
--- a/fs/xfs/xfs_ondisk.h
+++ b/fs/xfs/xfs_ondisk.h
@@ -189,6 +189,10 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_VALUE(XFS_DQ_BIGTIME_EXPIRY_MIN << XFS_DQ_BIGTIME_SHIFT, 4);
XFS_CHECK_VALUE(XFS_DQ_BIGTIME_EXPIRY_MAX << XFS_DQ_BIGTIME_SHIFT,
16299260424LL);
+
+ /* fs-verity descriptor xattr name */
+ XFS_CHECK_VALUE(strlen(XFS_VERITY_DESCRIPTOR_NAME),
+ XFS_VERITY_DESCRIPTOR_NAME_LEN);
}

#endif /* __XFS_ONDISK_H */
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index d40de32362b1..b6e99ed3b187 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -30,6 +30,7 @@
#include "xfs_filestream.h"
#include "xfs_quota.h"
#include "xfs_sysfs.h"
+#include "xfs_verity.h"
#include "xfs_ondisk.h"
#include "xfs_rmap_item.h"
#include "xfs_refcount_item.h"
@@ -1489,6 +1490,9 @@ xfs_fs_fill_super(
sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP | QTYPE_MASK_PRJ;
#endif
sb->s_op = &xfs_super_operations;
+#ifdef CONFIG_FS_VERITY
+ sb->s_vop = &xfs_verity_ops;
+#endif

/*
* Delay mount work if the debug hook is set. This is debug
@@ -1685,6 +1689,10 @@ xfs_fs_fill_super(
xfs_warn(mp,
"EXPERIMENTAL Large extent counts feature in use. Use at your own risk!");

+ if (xfs_has_verity(mp))
+ xfs_alert(mp,
+ "EXPERIMENTAL fs-verity feature in use. Use at your own risk!");
+
error = xfs_mountfs(mp);
if (error)
goto out_filestream_unmount;
diff --git a/fs/xfs/xfs_verity.c b/fs/xfs/xfs_verity.c
new file mode 100644
index 000000000000..a9874ff4efcd
--- /dev/null
+++ b/fs/xfs/xfs_verity.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Red Hat, Inc.
+ */
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_attr.h"
+#include "xfs_verity.h"
+#include "xfs_bmap_util.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+
+static int
+xfs_get_verity_descriptor(
+ struct inode *inode,
+ void *buf,
+ size_t buf_size)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ int error = 0;
+ struct xfs_da_args args = {
+ .dp = ip,
+ .attr_filter = XFS_ATTR_VERITY,
+ .name = (const uint8_t *)XFS_VERITY_DESCRIPTOR_NAME,
+ .namelen = XFS_VERITY_DESCRIPTOR_NAME_LEN,
+ .value = buf,
+ .valuelen = buf_size,
+ };
+
+ /*
+ * The fact that (returned attribute size) == (provided buf_size) is
+ * checked by xfs_attr_copy_value() (returns -ERANGE)
+ */
+ error = xfs_attr_get(&args);
+ if (error)
+ return error;
+
+ return args.valuelen;
+}
+
+static int
+xfs_begin_enable_verity(
+ struct file *filp)
+{
+ struct inode *inode = file_inode(filp);
+ struct xfs_inode *ip = XFS_I(inode);
+ int error = 0;
+
+ ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+
+ if (IS_DAX(inode))
+ return -EINVAL;
+
+ if (xfs_iflags_test(ip, XFS_IVERITY_CONSTRUCTION))
+ return -EBUSY;
+ xfs_iflags_set(ip, XFS_IVERITY_CONSTRUCTION);
+
+ return error;
+}
+
+static int
+xfs_end_enable_verity(
+ struct file *filp,
+ const void *desc,
+ size_t desc_size,
+ u64 merkle_tree_size)
+{
+ struct inode *inode = file_inode(filp);
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+ struct xfs_trans *tp;
+ struct xfs_da_args args = {
+ .dp = ip,
+ .whichfork = XFS_ATTR_FORK,
+ .attr_filter = XFS_ATTR_VERITY,
+ .attr_flags = XATTR_CREATE,
+ .name = (const uint8_t *)XFS_VERITY_DESCRIPTOR_NAME,
+ .namelen = XFS_VERITY_DESCRIPTOR_NAME_LEN,
+ .value = (void *)desc,
+ .valuelen = desc_size,
+ };
+ int error = 0;
+
+ ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+
+ /* fs-verity failed, just cleanup */
+ if (desc == NULL)
+ goto out;
+
+ error = xfs_attr_set(&args);
+ if (error)
+ goto out;
+
+ /* Set fsverity inode flag */
+ error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_ichange,
+ 0, 0, false, &tp);
+ if (error)
+ goto out;
+
+ /*
+ * Ensure that we've persisted the verity information before we enable
+ * it on the inode and tell the caller we have sealed the inode.
+ */
+ ip->i_diflags2 |= XFS_DIFLAG2_VERITY;
+
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ xfs_trans_set_sync(tp);
+
+ error = xfs_trans_commit(tp);
+ xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+ if (!error)
+ inode->i_flags |= S_VERITY;
+
+out:
+ xfs_iflags_clear(ip, XFS_IVERITY_CONSTRUCTION);
+ return error;
+}
+
+static struct page *
+xfs_read_merkle_tree_page(
+ struct inode *inode,
+ pgoff_t index,
+ unsigned long num_ra_pages,
+ u8 log_blocksize)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ struct page *page = NULL;
+ __be64 name = cpu_to_be64(index << PAGE_SHIFT);
+ uint32_t bs = 1 << log_blocksize;
+ struct xfs_da_args args = {
+ .dp = ip,
+ .attr_filter = XFS_ATTR_VERITY,
+ .op_flags = XFS_DA_OP_BUFFER,
+ .name = (const uint8_t *)&name,
+ .namelen = sizeof(__be64),
+ .valuelen = bs,
+ };
+ int error = 0;
+
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ return ERR_PTR(-ENOMEM);
+
+ error = xfs_attr_get(&args);
+ if (error) {
+ kmem_free(args.value);
+ xfs_buf_rele(args.bp);
+ put_page(page);
+ return ERR_PTR(-EFAULT);
+ }
+
+ if (args.bp->b_flags & XBF_VERITY_CHECKED)
+ SetPageChecked(page);
+
+ page->private = (unsigned long)args.bp;
+ memcpy(page_address(page), args.value, args.valuelen);
+
+ kmem_free(args.value);
+ return page;
+}
+
+static int
+xfs_write_merkle_tree_block(
+ struct inode *inode,
+ const void *buf,
+ u64 pos,
+ unsigned int size)
+{
+ struct xfs_inode *ip = XFS_I(inode);
+ __be64 name = cpu_to_be64(pos);
+ struct xfs_da_args args = {
+ .dp = ip,
+ .whichfork = XFS_ATTR_FORK,
+ .attr_filter = XFS_ATTR_VERITY,
+ .attr_flags = XATTR_CREATE,
+ .name = (const uint8_t *)&name,
+ .namelen = sizeof(__be64),
+ .value = (void *)buf,
+ .valuelen = size,
+ };
+
+ return xfs_attr_set(&args);
+}
+
+static void
+xfs_drop_page(
+ struct page *page)
+{
+ struct xfs_buf *buf = (struct xfs_buf *)page->private;
+
+ ASSERT(buf != NULL);
+
+ if (PageChecked(page))
+ buf->b_flags |= XBF_VERITY_CHECKED;
+
+ xfs_buf_rele(buf);
+ put_page(page);
+}
+
+const struct fsverity_operations xfs_verity_ops = {
+ .begin_enable_verity = &xfs_begin_enable_verity,
+ .end_enable_verity = &xfs_end_enable_verity,
+ .get_verity_descriptor = &xfs_get_verity_descriptor,
+ .read_merkle_tree_page = &xfs_read_merkle_tree_page,
+ .write_merkle_tree_block = &xfs_write_merkle_tree_block,
+ .drop_page = &xfs_drop_page,
+};
diff --git a/fs/xfs/xfs_verity.h b/fs/xfs/xfs_verity.h
new file mode 100644
index 000000000000..ae5d87ca32a8
--- /dev/null
+++ b/fs/xfs/xfs_verity.h
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Red Hat, Inc.
+ */
+#ifndef __XFS_VERITY_H__
+#define __XFS_VERITY_H__
+
+#include <linux/fsverity.h>
+
+#define XFS_VERITY_DESCRIPTOR_NAME "verity_descriptor"
+#define XFS_VERITY_DESCRIPTOR_NAME_LEN 17
+
+#ifdef CONFIG_FS_VERITY
+extern const struct fsverity_operations xfs_verity_ops;
+#else
+#define xfs_verity_ops NULL
+#endif /* CONFIG_FS_VERITY */
+
+#endif /* __XFS_VERITY_H__ */
--
2.38.4