[PATCH v2] ksmbd: validate credit charge after validating SMB2 PDU body size

[PATCH v2] ksmbd: validate credit charge after validating SMB2 PDU body size

[Namjae Jeon]

From: Ralph Boehme <slow@samba.org>

smb2_validate_credit_charge() accesses fields in the SMB2 PDU body,
but until smb2_calc_size() is called the PDU has not yet been verified
to be large enough to access the PDU dynamic part length field.

Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Ralph Boehme <slow@samba.org>
---
 v2:
  - add goto statement not to skip to validate credit charge.
  - fix conflict with credit management patch.

 fs/ksmbd/smb2misc.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/ksmbd/smb2misc.c b/fs/ksmbd/smb2misc.c
index e7e441c8f050..030ca57c3784 100644
--- a/fs/ksmbd/smb2misc.c
+++ b/fs/ksmbd/smb2misc.c
@@ -400,26 +400,20 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 		}
 	}
 
-	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
-	    smb2_validate_credit_charge(work->conn, hdr)) {
-		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
-		return 1;
-	}
-
 	if (smb2_calc_size(hdr, &clc_len))
 		return 1;
 
 	if (len != clc_len) {
 		/* client can return one byte more due to implied bcc[0] */
 		if (clc_len == len + 1)
-			return 0;
+			goto validate_credit;
 
 		/*
 		 * Some windows servers (win2016) will pad also the final
 		 * PDU in a compound to 8 bytes.
 		 */
 		if (ALIGN(clc_len, 8) == len)
-			return 0;
+			goto validate_credit;
 
 		/*
 		 * windows client also pad up to 8 bytes when compounding.
@@ -432,7 +426,7 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 				    "cli req padded more than expected. Length %d not %d for cmd:%d mid:%llu\n",
 				    len, clc_len, command,
 				    le64_to_cpu(hdr->MessageId));
-			return 0;
+			goto validate_credit;
 		}
 
 		ksmbd_debug(SMB,
@@ -443,6 +437,13 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
 		return 1;
 	}
 
+validate_credit:
+	if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
+	    smb2_validate_credit_charge(work->conn, hdr)) {
+		work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
+		return 1;
+	}
+
 	return 0;
 }
 
-- 
2.25.1

Re: [PATCH v2] ksmbd: validate credit charge after validating SMB2 PDU body size

[Hyunchul Lee]

Acked-by: Hyunchul Lee <hyc.lee@gmail.com>

2021년 10월 15일 (금) 오후 5:19, Namjae Jeon <linkinjeon@kernel.org>님이 작성:
>
> From: Ralph Boehme <slow@samba.org>
>
> smb2_validate_credit_charge() accesses fields in the SMB2 PDU body,
> but until smb2_calc_size() is called the PDU has not yet been verified
> to be large enough to access the PDU dynamic part length field.
>
> Acked-by: Namjae Jeon <linkinjeon@kernel.org>
> Signed-off-by: Ralph Boehme <slow@samba.org>
> ---
>  v2:
>   - add goto statement not to skip to validate credit charge.
>   - fix conflict with credit management patch.
>
>  fs/ksmbd/smb2misc.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/fs/ksmbd/smb2misc.c b/fs/ksmbd/smb2misc.c
> index e7e441c8f050..030ca57c3784 100644
> --- a/fs/ksmbd/smb2misc.c
> +++ b/fs/ksmbd/smb2misc.c
> @@ -400,26 +400,20 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
>                 }
>         }
>
> -       if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
> -           smb2_validate_credit_charge(work->conn, hdr)) {
> -               work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
> -               return 1;
> -       }
> -
>         if (smb2_calc_size(hdr, &clc_len))
>                 return 1;
>
>         if (len != clc_len) {
>                 /* client can return one byte more due to implied bcc[0] */
>                 if (clc_len == len + 1)
> -                       return 0;
> +                       goto validate_credit;
>
>                 /*
>                  * Some windows servers (win2016) will pad also the final
>                  * PDU in a compound to 8 bytes.
>                  */
>                 if (ALIGN(clc_len, 8) == len)
> -                       return 0;
> +                       goto validate_credit;
>
>                 /*
>                  * windows client also pad up to 8 bytes when compounding.
> @@ -432,7 +426,7 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
>                                     "cli req padded more than expected. Length %d not %d for cmd:%d mid:%llu\n",
>                                     len, clc_len, command,
>                                     le64_to_cpu(hdr->MessageId));
> -                       return 0;
> +                       goto validate_credit;
>                 }
>
>                 ksmbd_debug(SMB,
> @@ -443,6 +437,13 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work)
>                 return 1;
>         }
>
> +validate_credit:
> +       if ((work->conn->vals->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU) &&
> +           smb2_validate_credit_charge(work->conn, hdr)) {
> +               work->conn->ops->set_rsp_status(work, STATUS_INVALID_PARAMETER);
> +               return 1;
> +       }
> +
>         return 0;
>  }
>
> --
> 2.25.1
>


-- 
Thanks,
Hyunchul