[PATCH 1/2] cifs: Extend ->set_EA() callback to allow operate on reparse point

[PATCH 1/2] cifs: Extend ->set_EA() callback to allow operate on reparse point

[Pali Rohár]

Upcoming changes for setting EAs needs to operate on the reparse point
itself. This change extend >set_EA() callback with a new boolean parameter
to allow it.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/smb/client/cifsglob.h  |  1 +
 fs/smb/client/cifsproto.h |  3 ++-
 fs/smb/client/cifssmb.c   | 20 +++++++++++++++++++-
 fs/smb/client/smb2ops.c   |  6 ++++--
 fs/smb/client/xattr.c     |  3 ++-
 5 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index fffb1b2dc09f..6a84d5eae578 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -571,6 +571,7 @@ struct smb_version_operations {
 			const unsigned char *, const unsigned char *, char *,
 			size_t, struct cifs_sb_info *);
 	int (*set_EA)(const unsigned int, struct cifs_tcon *, const char *,
+			bool open_reparse_point,
 			const char *, const void *, const __u16,
 			const struct nls_table *, struct cifs_sb_info *);
 	struct smb_ntsd * (*get_acl)(struct cifs_sb_info *cifssb, struct inode *ino,
diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index 4fbd42b98703..e449b33d9bdc 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -567,7 +567,8 @@ extern ssize_t CIFSSMBQAllEAs(const unsigned int xid, struct cifs_tcon *tcon,
 			const unsigned char *ea_name, char *EAData,
 			size_t bufsize, struct cifs_sb_info *cifs_sb);
 extern int CIFSSMBSetEA(const unsigned int xid, struct cifs_tcon *tcon,
-		const char *fileName, const char *ea_name,
+		const char *fileName, bool open_reparse_point,
+		const char *ea_name,
 		const void *ea_value, const __u16 ea_value_len,
 		const struct nls_table *nls_codepage,
 		struct cifs_sb_info *cifs_sb);
diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c
index 54183d7dcc85..44b3f7be0f58 100644
--- a/fs/smb/client/cifssmb.c
+++ b/fs/smb/client/cifssmb.c
@@ -2885,6 +2885,7 @@ struct inode *cifs_create_reparse_inode(struct cifs_open_info_data *data,
 			rc = CIFSSMBSetEA(xid,
 					  tcon,
 					  full_path,
+					  true /* open reparse point */,
 					  &ea->ea_data[0],
 					  &ea->ea_data[ea->ea_name_length+1],
 					  le16_to_cpu(ea->ea_value_length),
@@ -5961,7 +5962,8 @@ CIFSSMBQAllEAs(const unsigned int xid, struct cifs_tcon *tcon,
 
 int
 CIFSSMBSetEA(const unsigned int xid, struct cifs_tcon *tcon,
-	     const char *fileName, const char *ea_name, const void *ea_value,
+	     const char *fileName, bool open_reparse_point,
+	     const char *ea_name, const void *ea_value,
 	     const __u16 ea_value_len, const struct nls_table *nls_codepage,
 	     struct cifs_sb_info *cifs_sb)
 {
@@ -5974,6 +5976,22 @@ CIFSSMBSetEA(const unsigned int xid, struct cifs_tcon *tcon,
 	__u16 params, param_offset, byte_count, offset, count;
 	int remap = cifs_remap(cifs_sb);
 
+	/*
+	 * On NT systems which supports reparse points, the TRANS2_SET_PATH_INFORMATION
+	 * operates on the reparse point itself and not the path location where reparse
+	 * point redirects. So the behavior of TRANS2_SET_PATH_INFORMATION is as if the
+	 * path was opened with OPEN_REPARSE_POINT flag. Hence this SMB1 SetEA function
+	 * implements only the behavior of "open_reparse_point=true" parameter.
+	 *
+	 * TODO: Implement "open_reparse_point=false" support for SMB1 SetEA. For this
+	 * is needed to call NT OPEN without OPEN_REPARSE_POINT flag and then call
+	 * TRANS2_SET_FILE_INFORMATION.
+	 *
+	 * On systems which do not support reparse points, the behavior of of both
+	 * "open_reparse_point=true" and "open_reparse_point=false" is same.
+	 */
+	(void)open_reparse_point;
+
 	cifs_dbg(FYI, "In SetEA\n");
 SetEARetry:
 	rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index b2aa802c7521..7ce8472a90dd 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -1155,7 +1155,8 @@ smb2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
 
 static int
 smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
-	    const char *path, const char *ea_name, const void *ea_value,
+	    const char *path, bool open_reparse_point,
+	    const char *ea_name, const void *ea_value,
 	    const __u16 ea_value_len, const struct nls_table *nls_codepage,
 	    struct cifs_sb_info *cifs_sb)
 {
@@ -1256,7 +1257,8 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 		.path = path,
 		.desired_access = FILE_WRITE_EA,
 		.disposition = FILE_OPEN,
-		.create_options = cifs_create_options(cifs_sb, 0),
+		.create_options = cifs_create_options(cifs_sb,
+				open_reparse_point ? OPEN_REPARSE_POINT : 0),
 		.fid = &fid,
 		.replay = !!(retries),
 	};
diff --git a/fs/smb/client/xattr.c b/fs/smb/client/xattr.c
index b88fa04f5792..26193249dbd8 100644
--- a/fs/smb/client/xattr.c
+++ b/fs/smb/client/xattr.c
@@ -155,7 +155,8 @@ static int cifs_xattr_set(const struct xattr_handler *handler,
 
 		if (pTcon->ses->server->ops->set_EA) {
 			rc = pTcon->ses->server->ops->set_EA(xid, pTcon,
-				full_path, name, value, (__u16)size,
+				full_path, false /* open reparse point */,
+				name, value, (__u16)size,
 				cifs_sb->local_nls, cifs_sb);
 			if (rc == 0)
 				inode_set_ctime_current(inode);
-- 
2.20.1

[PATCH 2/2] cifs: Create native Window socket file compatible also with WSL subsystem

[Pali Rohár]

After creating a native socket via the IO_REPARSE_TAG_AF_UNIX reparse
point, try to set also the WSL EA $LXMOD.

This makes the native Win32 / NT socket file recognized also under
WSL subsystem. WSL subsystem uses same reparse point tag but requires also
to be EA $LXMOD set.

Fixes: 45a99d5d1173 ("cifs: Add support for creating native Windows sockets")
Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/smb/client/reparse.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index ee4af153e7af..74a36957e8cb 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -381,7 +381,7 @@ static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
 
 static int create_native_socket(const unsigned int xid, struct inode *inode,
 				struct dentry *dentry, struct cifs_tcon *tcon,
-				const char *full_path)
+				const char *full_path, umode_t mode)
 {
 	struct reparse_data_buffer buf = {
 		.ReparseTag = cpu_to_le32(IO_REPARSE_TAG_AF_UNIX),
@@ -395,6 +395,8 @@ static int create_native_socket(const unsigned int xid, struct inode *inode,
 		.iov_base = &buf,
 		.iov_len = sizeof(buf),
 	};
+	const __le64 xattr_mode_val = cpu_to_le64(mode);
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	struct inode *new;
 	int rc = 0;
 
@@ -405,6 +407,28 @@ static int create_native_socket(const unsigned int xid, struct inode *inode,
 		d_instantiate(dentry, new);
 	else
 		rc = PTR_ERR(new);
+
+	/*
+	 * Try to set also optional WSL EA $LXMOD but ignore errors.
+	 * WSL socket and native Win32/NT sockets uses same reparse point
+	 * tag IO_REPARSE_TAG_AF_UNIX. WSL subsystem additionally requires
+	 * EA $LXMOD to be set with the S_IFSOCK value. So setting this EA
+	 * allows native socket to be recognized also by WSL subsystem.
+	 * Note that setting of both EAs and reparse points is not supported
+	 * by NTFS filesystem on Windows 8 / Windows Server 2012 and always
+	 * fails. So ignore failures from this set_EA call.
+	 */
+#ifdef CONFIG_CIFS_XATTR
+	if (!rc && tcon->ses->server->ops->set_EA &&
+	    (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_EXTENDED_ATTRIBUTES))
+		tcon->ses->server->ops->set_EA(xid, tcon, full_path,
+					       true /* open reparse point */,
+					       SMB2_WSL_XATTR_MODE,
+					       &xattr_mode_val,
+					       SMB2_WSL_XATTR_MODE_SIZE,
+					       cifs_sb->local_nls, cifs_sb);
+#endif
+
 	cifs_free_open_info(&data);
 	return rc;
 }
@@ -714,7 +738,7 @@ int mknod_reparse(unsigned int xid, struct inode *inode,
 	struct smb3_fs_context *ctx = CIFS_SB(inode->i_sb)->ctx;
 
 	if (S_ISSOCK(mode) && !ctx->nonativesocket && ctx->reparse_type != CIFS_REPARSE_TYPE_NONE)
-		return create_native_socket(xid, inode, dentry, tcon, full_path);
+		return create_native_socket(xid, inode, dentry, tcon, full_path, mode);
 
 	switch (ctx->reparse_type) {
 	case CIFS_REPARSE_TYPE_NFS:
-- 
2.20.1

Re: [PATCH 2/2] cifs: Create native Window socket file compatible also with WSL subsystem

[Pali Rohár]

Hello, I would like to remind this change.

On Saturday 12 July 2025 18:10:12 Pali Rohár wrote:
> After creating a native socket via the IO_REPARSE_TAG_AF_UNIX reparse
> point, try to set also the WSL EA $LXMOD.
> 
> This makes the native Win32 / NT socket file recognized also under
> WSL subsystem. WSL subsystem uses same reparse point tag but requires also
> to be EA $LXMOD set.
> 
> Fixes: 45a99d5d1173 ("cifs: Add support for creating native Windows sockets")
> Signed-off-by: Pali Rohár <pali@kernel.org>
> ---
>  fs/smb/client/reparse.c | 28 ++++++++++++++++++++++++++--
>  1 file changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
> index ee4af153e7af..74a36957e8cb 100644
> --- a/fs/smb/client/reparse.c
> +++ b/fs/smb/client/reparse.c
> @@ -381,7 +381,7 @@ static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
>  
>  static int create_native_socket(const unsigned int xid, struct inode *inode,
>  				struct dentry *dentry, struct cifs_tcon *tcon,
> -				const char *full_path)
> +				const char *full_path, umode_t mode)
>  {
>  	struct reparse_data_buffer buf = {
>  		.ReparseTag = cpu_to_le32(IO_REPARSE_TAG_AF_UNIX),
> @@ -395,6 +395,8 @@ static int create_native_socket(const unsigned int xid, struct inode *inode,
>  		.iov_base = &buf,
>  		.iov_len = sizeof(buf),
>  	};
> +	const __le64 xattr_mode_val = cpu_to_le64(mode);
> +	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
>  	struct inode *new;
>  	int rc = 0;
>  
> @@ -405,6 +407,28 @@ static int create_native_socket(const unsigned int xid, struct inode *inode,
>  		d_instantiate(dentry, new);
>  	else
>  		rc = PTR_ERR(new);
> +
> +	/*
> +	 * Try to set also optional WSL EA $LXMOD but ignore errors.
> +	 * WSL socket and native Win32/NT sockets uses same reparse point
> +	 * tag IO_REPARSE_TAG_AF_UNIX. WSL subsystem additionally requires
> +	 * EA $LXMOD to be set with the S_IFSOCK value. So setting this EA
> +	 * allows native socket to be recognized also by WSL subsystem.
> +	 * Note that setting of both EAs and reparse points is not supported
> +	 * by NTFS filesystem on Windows 8 / Windows Server 2012 and always
> +	 * fails. So ignore failures from this set_EA call.
> +	 */
> +#ifdef CONFIG_CIFS_XATTR
> +	if (!rc && tcon->ses->server->ops->set_EA &&
> +	    (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_EXTENDED_ATTRIBUTES))
> +		tcon->ses->server->ops->set_EA(xid, tcon, full_path,
> +					       true /* open reparse point */,
> +					       SMB2_WSL_XATTR_MODE,
> +					       &xattr_mode_val,
> +					       SMB2_WSL_XATTR_MODE_SIZE,
> +					       cifs_sb->local_nls, cifs_sb);
> +#endif
> +
>  	cifs_free_open_info(&data);
>  	return rc;
>  }
> @@ -714,7 +738,7 @@ int mknod_reparse(unsigned int xid, struct inode *inode,
>  	struct smb3_fs_context *ctx = CIFS_SB(inode->i_sb)->ctx;
>  
>  	if (S_ISSOCK(mode) && !ctx->nonativesocket && ctx->reparse_type != CIFS_REPARSE_TYPE_NONE)
> -		return create_native_socket(xid, inode, dentry, tcon, full_path);
> +		return create_native_socket(xid, inode, dentry, tcon, full_path, mode);
>  
>  	switch (ctx->reparse_type) {
>  	case CIFS_REPARSE_TYPE_NFS:
> -- 
> 2.20.1
>