linux-kernel - Re: [PATCH] ksmbd: Fix to handle removal of rfc1002 header from smb

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Message-ID: <CAKYAXd81W9xERg0iOWm81hcfA1KsWj1TrUvsRP6nqJ_aZcgz0w@mail.gmail.com>
Date: Fri, 19 Dec 2025 00:55:25 +0900
From: Namjae Jeon <linkinjeon@...nel.org>
To: ChenXiaoSong <chenxiaosong.chenxiaosong@...ux.dev>
Cc: David Howells <dhowells@...hat.com>, Steve French <sfrench@...ba.org>, 
	Sergey Senozhatsky <senozhatsky@...omium.org>, Tom Talpey <tom@...pey.com>, 
	Paulo Alcantara <pc@...guebit.org>, Shyam Prasad N <sprasad@...rosoft.com>, linux-cifs@...r.kernel.org, 
	netfs@...ts.linux.dev, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ksmbd: Fix to handle removal of rfc1002 header from smb_hdr

On Fri, Dec 19, 2025 at 12:47 AM ChenXiaoSong
<chenxiaosong.chenxiaosong@...ux.dev> wrote:
>
> Hi David,
>
> Since the size of `struct smb_hdr` has changed, the value of
> `SMB1_MIN_SUPPORTED_HEADER_SIZE` should also be updated to
> `(sizeof(struct smb_hdr) + 4)`. `SMB1_MIN_SUPPORTED_HEADER_SIZE` is used
> in `ksmbd_conn_handler_loop()`.
Right. And there are other places that need to be changed as well, I
will check it.
Thanks!
>
> Thanks,
> ChenXiaoSong.
>
> On 12/18/25 11:09 PM, ChenXiaoSong wrote:
> > `ksmbd_conn_handler_loop()` calls `get_rfc1002_len()`. Does this need to
> > be updated as well?
> >
> > Thanks,
> > ChenXiaoSong.
> >
> > On 12/18/25 10:48 PM, David Howells wrote:
> >> Hi Namjae,
> >>
> >> Does this (untested) patch fix the problem for you?
> >>
> >> David
> >> ---
> >> The commit that removed the RFC1002 header from struct smb_hdr didn't
> >> also
> >> fix the places in ksmbd that use it in order to provide graceful
> >> rejection
> >> of SMB1 protocol requests.
> >>
> >> Fixes: 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr")
> >> Reported-by: Namjae Jeon <linkinjeon@...nel.org>
> >> Link: https://lore.kernel.org/r/
> >> CAKYAXd9Ju4MFkkH5Jxfi1mO0AWEr=R35M3vQ_Xa7Yw34JoNZ0A@...l.gmail.com/
> >> Signed-off-by: David Howells <dhowells@...hat.com>
> >> cc: Steve French <sfrench@...ba.org>
> >> cc: Sergey Senozhatsky <senozhatsky@...omium.org>
> >> cc: Tom Talpey <tom@...pey.com>
> >> cc: Paulo Alcantara <pc@...guebit.org>
> >> cc: Shyam Prasad N <sprasad@...rosoft.com>
> >> cc: linux-cifs@...r.kernel.org
> >> cc: netfs@...ts.linux.dev
> >> cc: linux-fsdevel@...r.kernel.org
> >> ---
> >>   fs/smb/server/server.c     |    2 +-
> >>   fs/smb/server/smb_common.c |   10 +++++-----
> >>   2 files changed, 6 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
> >> index 3cea16050e4f..bedc8390b6db 100644
> >> --- a/fs/smb/server/server.c
> >> +++ b/fs/smb/server/server.c
> >> @@ -95,7 +95,7 @@ static inline int check_conn_state(struct ksmbd_work
> >> *work)
> >>       if (ksmbd_conn_exiting(work->conn) ||
> >>           ksmbd_conn_need_reconnect(work->conn)) {
> >> -        rsp_hdr = work->response_buf;
> >> +        rsp_hdr = smb2_get_msg(work->response_buf);
> >>           rsp_hdr->Status.CifsError = STATUS_CONNECTION_DISCONNECTED;
> >>           return 1;
> >>       }
> >> diff --git a/fs/smb/server/smb_common.c b/fs/smb/server/smb_common.c
> >> index b23203a1c286..d6084580b59d 100644
> >> --- a/fs/smb/server/smb_common.c
> >> +++ b/fs/smb/server/smb_common.c
> >> @@ -140,7 +140,7 @@ int ksmbd_verify_smb_message(struct ksmbd_work *work)
> >>       if (smb2_hdr->ProtocolId == SMB2_PROTO_NUMBER)
> >>           return ksmbd_smb2_check_message(work);
> >> -    hdr = work->request_buf;
> >> +    hdr = smb2_get_msg(work->request_buf);
> >>       if (*(__le32 *)hdr->Protocol == SMB1_PROTO_NUMBER &&
> >>           hdr->Command == SMB_COM_NEGOTIATE) {
> >>           work->conn->outstanding_credits++;
> >> @@ -278,7 +278,6 @@ static int ksmbd_negotiate_smb_dialect(void *buf)
> >>                             req->DialectCount);
> >>       }
> >> -    proto = *(__le32 *)((struct smb_hdr *)buf)->Protocol;
> >>       if (proto == SMB1_PROTO_NUMBER) {
> >>           struct smb_negotiate_req *req;
> >> @@ -320,8 +319,8 @@ static u16 get_smb1_cmd_val(struct ksmbd_work *work)
> >>    */
> >>   static int init_smb1_rsp_hdr(struct ksmbd_work *work)
> >>   {
> >> -    struct smb_hdr *rsp_hdr = (struct smb_hdr *)work->response_buf;
> >> -    struct smb_hdr *rcv_hdr = (struct smb_hdr *)work->request_buf;
> >> +    struct smb_hdr *rsp_hdr = (struct smb_hdr *)smb2_get_msg(work-
> >> >response_buf);
> >> +    struct smb_hdr *rcv_hdr = (struct smb_hdr *)smb2_get_msg(work-
> >> >request_buf);
> >>       rsp_hdr->Command = SMB_COM_NEGOTIATE;
> >>       *(__le32 *)rsp_hdr->Protocol = SMB1_PROTO_NUMBER;
> >> @@ -412,9 +411,10 @@ static int init_smb1_server(struct ksmbd_conn *conn)
> >>   int ksmbd_init_smb_server(struct ksmbd_conn *conn)
> >>   {
> >> +    struct smb_hdr *rcv_hdr = (struct smb_hdr *)smb2_get_msg(conn-
> >> >request_buf);
> >>       __le32 proto;
> >> -    proto = *(__le32 *)((struct smb_hdr *)conn->request_buf)->Protocol;
> >> +    proto = *(__le32 *)rcv_hdr->Protocol;
> >>       if (conn->need_neg == false) {
> >>           if (proto == SMB1_PROTO_NUMBER)
> >>               return -EINVAL;
> >>
> >>
> >
>