[PATCH 06/11] fs/ntfs3: add 'ugm' mount option to control storing uid/gid/mode in xattrs

[Konstantin Komarov]

On file creation ntfs3 stores the owner, group, mode and device
number in the WSL extended attributes $LXUID, $LXGID, $LXMOD and
$LXDEV, and may also write a POSIX ACL. These attributes are
meaningless to Windows, and the packed size of the EAs is recorded in
the directory entry as well, so every created file carries them.

Add a 'ugm' mount option controlling this. It is enabled by default,
preserving the current behaviour; mount with 'ugm=0' to create files
without the WSL attributes.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
---
 fs/ntfs3/inode.c   |  2 +-
 fs/ntfs3/ntfs_fs.h |  1 +
 fs/ntfs3/super.c   | 13 ++++++++++++-
 fs/ntfs3/xattr.c   |  7 +++++++
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index a3b2daaecb4d..7593a93466d9 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -1836,7 +1836,7 @@ int ntfs_create_inode(struct mnt_idmap *idmap, struct inode *dir,
 		inode->i_flags |= S_NOSEC;
 	}
 
-	if (!S_ISLNK(mode)) {
+	if (!S_ISLNK(mode) && sbi->options->ugm) {
 		/*
 		 * ntfs_init_acl and ntfs_save_wsl_perm update extended attribute.
 		 * The packed size of extended attribute is stored in direntry too.
diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index 9321b2608e84..90ccfde951dc 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -111,6 +111,7 @@ struct ntfs_mount_options {
 	unsigned nocase : 1; /* case insensitive. */
 	unsigned delalloc : 1; /* delay allocation. */
 	unsigned ads : 1; /* ads support. */
+	unsigned ugm : 1; /* store user/group/mode in xattr. */
 };
 
 /* Special value to unpack and deallocate. */
diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 7fd83027007b..cf67d34568d8 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -275,6 +275,8 @@ enum Opt {
 	Opt_delalloc_bool,
 	Opt_ads,
 	Opt_ads_bool,
+	Opt_ugm,
+	Opt_ugm_bool,
 	Opt_err,
 };
 
@@ -303,6 +305,8 @@ static const struct fs_parameter_spec ntfs_fs_parameters[] = {
 	fsparam_bool("delalloc",	Opt_delalloc_bool),
 	fsparam_flag("ads",		Opt_ads),
 	fsparam_bool("ads",		Opt_ads_bool),
+	fsparam_flag("ugm",		Opt_ugm),
+	fsparam_bool("ugm",		Opt_ugm_bool),
 	{}
 };
 // clang-format on
@@ -345,7 +349,7 @@ static int ntfs_fs_parse_param(struct fs_context *fc,
 		pr_err("ntfs3: unknown option \"%s\". Use uid,gid,umask,"
 		       "dmask,fmask,sys_immutable,discard,force,sparse,"
 		       "nohidden,hide_dot_files,windows_names,showmeta,acl,"
-		       "iocharset,prealloc,nocase,delalloc,ads",
+		       "iocharset,prealloc,nocase,delalloc,ads,ugm",
 		       param->key);
 		return -ENOPARAM;
 	}
@@ -443,6 +447,12 @@ static int ntfs_fs_parse_param(struct fs_context *fc,
 	case Opt_ads_bool:
 		opts->ads = result.boolean;
 		break;
+	case Opt_ugm:
+		opts->ugm = 1;
+		break;
+	case Opt_ugm_bool:
+		opts->ugm = result.boolean;
+		break;
 	default:
 		/* Should not be here unless we forget add case. */
 		return -EINVAL;
@@ -1905,6 +1915,7 @@ static int ntfs_init_fs_context(struct fs_context *fc)
 	opts->fs_fmask_inv = opts->fs_dmask_inv = ~current_umask();
 	opts->prealloc = 1;
 	opts->ads = 1;
+	opts->ugm = 1;
 
 #ifdef CONFIG_NTFS3_FS_POSIX_ACL
 	/* Set the default value 'acl' */
diff --git a/fs/ntfs3/xattr.c b/fs/ntfs3/xattr.c
index 2cf45bdd93d5..d6ad06415318 100644
--- a/fs/ntfs3/xattr.c
+++ b/fs/ntfs3/xattr.c
@@ -1015,6 +1015,13 @@ int ntfs_save_wsl_perm(struct inode *inode, __le32 *ea_size)
 	__le32 value;
 	struct ntfs_inode *ni = ntfs_i(inode);
 
+	if (!ni->mi.sbi->options->ugm) {
+		/* Do not save uid/gid/mode/dev in xattr. */
+		if (ea_size)
+			*ea_size = 0;
+		return 0;
+	}
+
 	ni_lock(ni);
 	value = cpu_to_le32(i_uid_read(inode));
 	err = ntfs_set_ea(inode, "$LXUID", sizeof("$LXUID") - 1, &value,
-- 
2.43.0