Re: [PATCH v1 1/2] cifs: set server->cipher_type to AES-128-CCM for SMB3.0

[Steve French <smfrench@gmail.com>]

Added cc:stable

On Fri, May 21, 2021 at 10:19 AM Aurélien Aptel <aaptel@suse.com> wrote:
>
> From: Aurelien Aptel <aaptel@suse.com>
>
> SMB3.0 doesn't have encryption negotiate context but simply uses
> the SMB2_GLOBAL_CAP_ENCRYPTION flag.
>
> When that flag is present in the neg response cifs.ko uses AES-128-CCM
> which is the only cipher available in this context.
>
> cipher_type was set to the server cipher only when parsing encryption
> negotiate context (SMB3.1.1).
>
> For SMB3.0 it was set to 0. This means cipher_type value can be 0 or 1
> for AES-128-CCM.
>
> Fix this by checking for SMB3.0 and encryption capability and setting
> cipher_type appropriately.
>
> Signed-off-by: Aurelien Aptel <aaptel@suse.com>
> ---
>  fs/cifs/smb2pdu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 9f24eb88297a..c205f93e0a10 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -958,6 +958,13 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
>         /* Internal types */
>         server->capabilities |= SMB2_NT_FIND | SMB2_LARGE_FILES;
>
> +       /*
> +        * SMB3.0 supports only 1 cipher and doesn't have a encryption neg context
> +        * Set the cipher type manually.
> +        */
> +       if (server->dialect == SMB30_PROT_ID && (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION))
> +               server->cipher_type = SMB2_ENCRYPTION_AES128_CCM;
> +
>         security_blob = smb2_get_data_area_len(&blob_offset, &blob_length,
>                                                (struct smb2_sync_hdr *)rsp);
>         /*
> --
> 2.31.1
>


-- 
Thanks,

Steve