Re: [PATCH RESEND 06/11] cifs: Validate presence of EA $LXMOD for WSL reparse points

If this EA is missing, does Linux client still recognize it (not
talking about WSL just what Linux client would see)?

On Mon, Jul 6, 2026 at 1:51 PM Pali Rohár <[email protected]> wrote:
>
> S_DT part of xattr $LXMOD is mandatory for all WSL reparse points except the
> WSL symlink and Win32 socket. Microsoft WSL subsystem does not recognize
> them without xattr $LXMOD too, and treat such inodes as regular files.
>
> Fixes: ef201e8759d2 ("cifs: Validate EAs for WSL reparse points")
> Fixes: 78e26bec4d6d ("smb: client: parse uid, gid, mode and dev from WSL reparse points")
> Signed-off-by: Pali Rohár <[email protected]>
> ---
>  fs/smb/client/reparse.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
> index 49a6a0cc2b61..99e93b56374f 100644
> --- a/fs/smb/client/reparse.c
> +++ b/fs/smb/client/reparse.c
> @@ -1124,6 +1124,7 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
>  {
>         struct smb2_file_full_ea_info *ea;
>         bool ignore_missing_eas = false;
> +       bool have_xattr_mode = false;
>         bool have_xattr_dev = false;
>         umode_t reparse_mode_type = 0;
>         u32 next = 0;
> @@ -1183,6 +1184,7 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
>                         if (S_DT(reparse_mode_type) != S_DT(le32_to_cpu(*(__le32 *)v)))
>                                 return false;
>                         fattr->cf_mode = (umode_t)le32_to_cpu(*(__le32 *)v);
> +                       have_xattr_mode = true;
>                 } else if (!strncmp(name, SMB2_WSL_XATTR_DEV, nlen)) {
>                         fattr->cf_rdev = reparse_mkdev(v);
>                         have_xattr_dev = true;
> @@ -1194,6 +1196,16 @@ static bool wsl_to_fattr(struct cifs_open_info_data *data,
>         if (!have_xattr_dev && (tag == IO_REPARSE_TAG_LX_CHR || tag == IO_REPARSE_TAG_LX_BLK))
>                 return ignore_missing_eas;
>
> +       /*
> +        * S_DT part of xattr MODE is mandatory for all WSL reparse points except the WSL symlink.
> +        * Microsoft WSL does not recognize them without xattr MODE too (except the WSL symlink).
> +        * IO_REPARSE_TAG_AF_UNIX is here an exception because this reparse point is used by both
> +        * WSL subsystem and native NT/WinAPI subsystems. And NT/WinAPI creates AF UNIX socket
> +        * without the xattr MODE and recognize it also without the xattr MODE.
> +        */
> +       if (!have_xattr_mode && (tag != IO_REPARSE_TAG_AF_UNIX && tag != IO_REPARSE_TAG_LX_SYMLINK))
> +               return ignore_missing_eas;
> +
>         fattr->cf_mode |= reparse_mode_type;
>         return true;
>  }
> --
> 2.20.1
>
>


-- 
Thanks,

Steve