fs: add FS_XFLAG_VERITY for fs-verity files

fs-verity introduced inode flag for inodes with enabled fs-verity on
them. This patch adds FS_XFLAG_VERITY file attribute which can be
retrieved with FS_IOC_FSGETXATTR ioctl() and file_getattr() syscall.

This flag is read-only and can not be set with corresponding set ioctl()
and file_setattr(). The FS_IOC_SETFLAGS requires file to be opened for
writing which is not allowed for verity files. The FS_IOC_FSSETXATTR and
file_setattr() clears this flag from the user input.

As this is now common flag for both flag interfaces (flags/xflags) add
it to overlapping flags list to exclude it from overwrite.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://patch.msgid.link/20260126115658.27656-2-aalbersh@kernel.org
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 412cf11e329852a97ab946b5fa4647b7b120706b..22b49b295d1f97e669f3de4dd0a8c8e82e6f8b81 100644 (file)
--- a/Documentation/filesystems/fsverity.rst
+++ b/Documentation/filesystems/fsverity.rst
@@ -341,6 +341,22 @@ the file has fs-verity enabled.  This can perform better than
 FS_IOC_GETFLAGS and FS_IOC_MEASURE_VERITY because it doesn't require
 opening the file, and opening verity files can be expensive.
 
+FS_IOC_FSGETXATTR
+-----------------
+
+Since Linux v7.0, the FS_IOC_FSGETXATTR ioctl sets FS_XFLAG_VERITY (0x00020000)
+in the returned flags when the file has verity enabled. Note that this attribute
+cannot be set with FS_IOC_FSSETXATTR as enabling verity requires input
+parameters. See FS_IOC_ENABLE_VERITY.
+
+file_getattr
+------------
+
+Since Linux v7.0, the file_getattr() syscall sets FS_XFLAG_VERITY (0x00020000)
+in the returned flags when the file has verity enabled. Note that this attribute
+cannot be set with file_setattr() as enabling verity requires input parameters.
+See FS_IOC_ENABLE_VERITY.
+
 .. _accessing_verity_files:
 
 Accessing verity files

diff --git a/fs/file_attr.c b/fs/file_attr.c
index f3704881c1265e176fb2a1639061a64cdd56a34c..dfde8740181714d34309034b8de0b4b3fa9a5895 100644 (file)
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -36,6 +36,8 @@ void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags)
                fa->flags |= FS_DAX_FL;
        if (fa->fsx_xflags & FS_XFLAG_PROJINHERIT)
                fa->flags |= FS_PROJINHERIT_FL;
+       if (fa->fsx_xflags & FS_XFLAG_VERITY)
+               fa->flags |= FS_VERITY_FL;
 }
 EXPORT_SYMBOL(fileattr_fill_xflags);
 
@@ -66,6 +68,8 @@ void fileattr_fill_flags(struct file_kattr *fa, u32 flags)
                fa->fsx_xflags |= FS_XFLAG_DAX;
        if (fa->flags & FS_PROJINHERIT_FL)
                fa->fsx_xflags |= FS_XFLAG_PROJINHERIT;
+       if (fa->flags & FS_VERITY_FL)
+               fa->fsx_xflags |= FS_XFLAG_VERITY;
 }
 EXPORT_SYMBOL(fileattr_fill_flags);
 

diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h
index f89dcfad3f8f36b4d2c48a8300d08d9d4c35ef0f..3780904a63a6c760f3ad684a72361001bf1bf2c9 100644 (file)
--- a/include/linux/fileattr.h
+++ b/include/linux/fileattr.h
@@ -7,16 +7,16 @@
 #define FS_COMMON_FL \
        (FS_SYNC_FL | FS_IMMUTABLE_FL | FS_APPEND_FL | \
         FS_NODUMP_FL | FS_NOATIME_FL | FS_DAX_FL | \
-        FS_PROJINHERIT_FL)
+        FS_PROJINHERIT_FL | FS_VERITY_FL)
 
 #define FS_XFLAG_COMMON \
        (FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND | \
         FS_XFLAG_NODUMP | FS_XFLAG_NOATIME | FS_XFLAG_DAX | \
-        FS_XFLAG_PROJINHERIT)
+        FS_XFLAG_PROJINHERIT | FS_XFLAG_VERITY)
 
 /* Read-only inode flags */
 #define FS_XFLAG_RDONLY_MASK \
-       (FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR)
+       (FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR | FS_XFLAG_VERITY)
 
 /* Flags to indicate valid value of fsx_ fields */
 #define FS_XFLAG_VALUES_MASK \

diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 66ca526cf786c761eb5bab1175e519f7f32cd764..70b2b661f42cb6e585436b6f5f00c7c977c15cdb 100644 (file)
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -253,6 +253,7 @@ struct file_attr {
 #define FS_XFLAG_FILESTREAM    0x00004000      /* use filestream allocator */
 #define FS_XFLAG_DAX           0x00008000      /* use DAX for IO */
 #define FS_XFLAG_COWEXTSIZE    0x00010000      /* CoW extent size allocator hint */
+#define FS_XFLAG_VERITY                0x00020000      /* fs-verity enabled */
 #define FS_XFLAG_HASATTR       0x80000000      /* no DIFLAG for this   */
 
 /* the read-only stuff doesn't really belong here, but any other place is