Re: [PATCH] smb: client: fix multiuser mount with krb5

On Tue, Aug 25, 2026 at 4:59 AM Paulo Alcantara <[email protected]> wrote:
>
> Customer reported that they could no longer mount their SMB shares
> with multiuser mount option and krb5.  Turned out that the client
> wasn't duplicating username option when creating multiuser
> connections, therefore failing to retrieve credentials as
> cifs.upcall(8) couldn't find them in keytab.
>
> Fix this by duplicating username option (if set) from original fs
> context before creating multiuser connections with krb5.
>
> Reproducer:
>
>   ```
>   $ ktutil
>   ktutil:  add_entry -password -p testuser -k 1 -e aes256-cts
>   Password for [email protected]:
>   ktutil:  write_kt /etc/krb5.keytab
>   ktutil:  quit
>   $ klist -ke
>   Keytab name: FILE:/etc/krb5.keytab
>   KVNO Principal
>    ---- ----------------------------------------------------------------
>      1 [email protected] (aes256-cts-hmac-sha1-96)
>   $ mount.cifs //w22-root2/scratch /mnt/1 -o \
>         uid=1000,sec=krb5,[email protected],multiuser
>   mount error(13): Permission denied
>   Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and
>   kernel log messages (dmesg)
>   ```
>
> Reported-by: Jacob Shivers <[email protected]>
> Fixes: 12b4c5d98cd7 ("smb: client: fix krb5 mount with username option")
> Signed-off-by: Paulo Alcantara <[email protected]>
> Cc: Ronnie Sahlberg <[email protected]>
> Cc: Shyam Prasad N <[email protected]>
> Cc: Tom Talpey <[email protected]>
> Cc: Bharath SM <[email protected]>
> Cc: Namjae Jeon <[email protected]>
> Cc: [email protected]
Reviewed-by: Namjae Jeon <[email protected]>
Thanks.