[PATCH v2 14/23] xfs: add attribute type for fs-verity

[Andrey Albershteyn]

The Merkle tree blocks and descriptor are stored in the extended
attributes of the inode. Add new attribute type for fs-verity
metadata. Add XFS_ATTR_INTERNAL_MASK to skip parent pointer and
fs-verity attributes as those are only for internal use. While we're
at it add a few comments in relevant places that internally visible
attributes are not suppose to be handled via interface defined in
xfs_xattr.c.

Signed-off-by: Andrey Albershteyn <aalbersh at redhat.com>
---
 fs/xfs/libxfs/xfs_da_format.h  | 10 +++++++++-
 fs/xfs/libxfs/xfs_log_format.h |  1 +
 fs/xfs/xfs_ioctl.c             |  5 +++++
 fs/xfs/xfs_trace.h             |  1 +
 fs/xfs/xfs_xattr.c             |  9 +++++++++
 5 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_da_format.h b/fs/xfs/libxfs/xfs_da_format.h
index 75b13807145d..2b5967befc2e 100644
--- a/fs/xfs/libxfs/xfs_da_format.h
+++ b/fs/xfs/libxfs/xfs_da_format.h
@@ -689,14 +689,22 @@ struct xfs_attr3_leafblock {
 #define	XFS_ATTR_ROOT_BIT	1	/* limit access to trusted attrs */
 #define	XFS_ATTR_SECURE_BIT	2	/* limit access to secure attrs */
 #define	XFS_ATTR_PARENT_BIT	3	/* parent pointer attrs */
+#define	XFS_ATTR_VERITY_BIT	4	/* verity merkle tree and descriptor */
 #define	XFS_ATTR_INCOMPLETE_BIT	7	/* attr in middle of create/delete */
 #define XFS_ATTR_LOCAL		(1u << XFS_ATTR_LOCAL_BIT)
 #define XFS_ATTR_ROOT		(1u << XFS_ATTR_ROOT_BIT)
 #define XFS_ATTR_SECURE		(1u << XFS_ATTR_SECURE_BIT)
 #define XFS_ATTR_PARENT		(1u << XFS_ATTR_PARENT_BIT)
+#define XFS_ATTR_VERITY		(1u << XFS_ATTR_VERITY_BIT)
 #define XFS_ATTR_INCOMPLETE	(1u << XFS_ATTR_INCOMPLETE_BIT)
 #define XFS_ATTR_NSP_ONDISK_MASK \
-			(XFS_ATTR_ROOT | XFS_ATTR_SECURE | XFS_ATTR_PARENT)
+			(XFS_ATTR_ROOT | XFS_ATTR_SECURE | XFS_ATTR_PARENT | \
+			 XFS_ATTR_VERITY)
+
+/*
+ * Internal attributes not exposed to the user
+ */
+#define XFS_ATTR_INTERNAL_MASK (XFS_ATTR_PARENT | XFS_ATTR_VERITY)
 
 /*
  * Alignment for namelist and valuelist entries (since they are mixed
diff --git a/fs/xfs/libxfs/xfs_log_format.h b/fs/xfs/libxfs/xfs_log_format.h
index 727b5a858028..678eacb7925c 100644
--- a/fs/xfs/libxfs/xfs_log_format.h
+++ b/fs/xfs/libxfs/xfs_log_format.h
@@ -968,6 +968,7 @@ struct xfs_icreate_log {
 #define XFS_ATTRI_FILTER_MASK		(XFS_ATTR_ROOT | \
 					 XFS_ATTR_SECURE | \
 					 XFS_ATTR_PARENT | \
+					 XFS_ATTR_VERITY | \
 					 XFS_ATTR_INCOMPLETE)
 
 /*
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 55bb01173cde..3d6d680b6cf3 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -351,6 +351,11 @@ static unsigned int
 xfs_attr_filter(
 	u32			ioc_flags)
 {
+	/*
+	 * Only externally visible attributes should be specified here.
+	 * Internally used attributes (such as parent pointers or fs-verity)
+	 * should not be exposed to userspace.
+	 */
 	if (ioc_flags & XFS_IOC_ATTR_ROOT)
 		return XFS_ATTR_ROOT;
 	if (ioc_flags & XFS_IOC_ATTR_SECURE)
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 9c0006c55fec..e842b9d145cb 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -79,6 +79,7 @@ struct xfs_perag;
 #define XFS_ATTR_FILTER_FLAGS \
 	{ XFS_ATTR_ROOT,	"ROOT" }, \
 	{ XFS_ATTR_SECURE,	"SECURE" }, \
+	{ XFS_ATTR_VERITY,	"VERITY" }, \
 	{ XFS_ATTR_INCOMPLETE,	"INCOMPLETE" }
 
 DECLARE_EVENT_CLASS(xfs_attr_list_class,
diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
index 7b9a0ed1b11f..5a71797fbd44 100644
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -20,6 +20,12 @@
 
 #include <linux/posix_acl_xattr.h>
 
+/*
+ * This file defines interface to work with externally visible extended
+ * attributes, such as those in system or security namespaces. This interface
+ * should not be used for internally used attributes (consider xfs_attr.c).
+ */
+
 /*
  * Get permission to use log-assisted atomic exchange of file extents.
  *
@@ -234,6 +240,9 @@ xfs_xattr_put_listent(
 
 	ASSERT(context->count >= 0);
 
+	if (flags & XFS_ATTR_INTERNAL_MASK)
+		return;
+
 	if (flags & XFS_ATTR_ROOT) {
 #ifdef CONFIG_XFS_POSIX_ACL
 		if (namelen == SGI_ACL_FILE_SIZE &&
-- 
2.38.4