Re: [PATCH v6 01/14] ksmbd: add the check to vaildate if stream protocol length exceeds maximum value

Namjae Jeon
2021-10-03T01:18:42Z

2021-10-02 22:11 GMT+09:00, Ralph Boehme <slow@samba.org>:
> From: Namjae Jeon <linkinjeon@kernel.org>
>
> This patch add MAX_STREAM_PROT_LEN macro and check if stream protocol
> length exceeds maximum value. opencode pdu size check in
> ksmbd_pdu_size_has_room().
>
> Cc: Tom Talpey <tom@talpey.com>
> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
> Cc: Ralph Böhme <slow@samba.org>
> Cc: Steve French <smfrench@gmail.com>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Acked-by: Hyunchul Lee <hyc.lee@gmail.com>
> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
> ---
> fs/ksmbd/connection.c | 9 +++++----
> fs/ksmbd/smb_common.c | 6 ------
> fs/ksmbd/smb_common.h | 4 ++--
> 3 files changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/fs/ksmbd/connection.c b/fs/ksmbd/connection.c
> index af086d35398a..e50353c50661 100644
> --- a/fs/ksmbd/connection.c
> +++ b/fs/ksmbd/connection.c
> @@ -296,10 +296,11 @@ int ksmbd_conn_handler_loop(void *p)
> pdu_size = get_rfc1002_len(hdr_buf);
> ksmbd_debug(CONN, "RFC1002 header %u bytes\n", pdu_size);
>
> - /* make sure we have enough to get to SMB header end */
> - if (!ksmbd_pdu_size_has_room(pdu_size)) {
> - ksmbd_debug(CONN, "SMB request too short (%u bytes)\n",
> - pdu_size);
> + /*
> + * Check if pdu size is valid (min : smb header size,
> + * max : 0x00FFFFFF).
> + */
> + if (pdu_size > MAX_STREAM_PROT_LEN) {
You changed this patch not to check header size check. I think that
this patch should be backed to original one. Because your patches are
clean-up patches, not fixes.
So you need to remove header size check here in "ksmbd: check PDU len
is at least header plus body size... ".

> continue;
> }
>
> diff --git a/fs/ksmbd/smb_common.c b/fs/ksmbd/smb_common.c
> index db8042a173d0..b6c4c7e960fa 100644
> --- a/fs/ksmbd/smb_common.c
> +++ b/fs/ksmbd/smb_common.c
> @@ -21,7 +21,6 @@ static const char basechars[43] =
> "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_-!@#$%";
> #define MAGIC_CHAR '~'
> #define PERIOD '.'
> #define mangle(V) ((char)(basechars[(V) % MANGLE_BASE]))
> -#define KSMBD_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb2_hdr))
>
> struct smb_protocol {
> int index;
> @@ -294,11 +293,6 @@ int ksmbd_init_smb_server(struct ksmbd_work *work)
> return 0;
> }
>
> -bool ksmbd_pdu_size_has_room(unsigned int pdu)
> -{
> - return (pdu >= KSMBD_MIN_SUPPORTED_HEADER_SIZE - 4);
> -}
> -
> int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int
> info_level,
> struct ksmbd_file *dir,
> struct ksmbd_dir_info *d_info,
> diff --git a/fs/ksmbd/smb_common.h b/fs/ksmbd/smb_common.h
> index 994abede27e9..6e79e7577f6b 100644
> --- a/fs/ksmbd/smb_common.h
> +++ b/fs/ksmbd/smb_common.h
> @@ -48,6 +48,8 @@
> #define CIFS_DEFAULT_IOSIZE (64 * 1024)
> #define MAX_CIFS_SMALL_BUFFER_SIZE 448 /* big enough for most */
>
> +#define MAX_STREAM_PROT_LEN 0x00FFFFFF
> +
> /* Responses when opening a file. */
> #define F_SUPERSEDED 0
> #define F_OPENED 1
> @@ -493,8 +495,6 @@ int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects,
> __le16 dialects_count);
>
> int ksmbd_init_smb_server(struct ksmbd_work *work);
>
> -bool ksmbd_pdu_size_has_room(unsigned int pdu);
> -
> struct ksmbd_kstat;
> int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work,
> int info_level,
> --
> 2.31.1
>
>