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Message-ID: <53A04BAE.8090709@gmail.com>
Date: Tue, 17 Jun 2014 10:07:42 -0400
From: Vlad Yasevich <vyasevich@...il.com>
To: Geir Ola Vaagland <geirola@...il.com>, netdev@...r.kernel.org
CC: linux-sctp@...r.kernel.org
Subject: Re: [PATCH net-next 2/6] Support for SCTP_RCVINFO ancillary data
On 06/17/2014 07:57 AM, Geir Ola Vaagland wrote:
> CC: Vlad Yasevich <vyasevich@...il.com>
> Signed-off-by: Geir Ola Vaagland <geirola@...il.com>
> ---
> include/net/sctp/ulpevent.h | 2 +
> include/uapi/linux/sctp.h | 23 ++++++++++++
> net/sctp/socket.c | 6 +++
> net/sctp/ulpevent.c | 91 +++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 122 insertions(+)
>
> diff --git a/include/net/sctp/ulpevent.h b/include/net/sctp/ulpevent.h
> index 27b9f5c..2f42831 100644
> --- a/include/net/sctp/ulpevent.h
> +++ b/include/net/sctp/ulpevent.h
> @@ -131,6 +131,8 @@ struct sctp_ulpevent *sctp_ulpevent_make_sender_dry_event(
>
> void sctp_ulpevent_read_sndrcvinfo(const struct sctp_ulpevent *event,
> struct msghdr *);
> +void sctp_ulpevent_read_rcvinfo(const struct sctp_ulpevent *event,
> + struct msghdr *);
Gah... This whole file doesn't conform to coding style. :(
Please make this change conform to style standards, and we can clean up the
file later.
> __u16 sctp_ulpevent_get_notification_type(const struct sctp_ulpevent *event);
>
> /* Is this event type enabled? */
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index a7db3b3..7e8736b 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -158,6 +158,27 @@ struct sctp_sndrcvinfo {
> };
>
> /*
> + * 5.3.5 SCTP Receive Information Structure (SCTP_RCVINFO)
> + *
> + * This cmsghdr structure specifies SCTP options for sendmsg().
> + *
> + * cmsg_level cmsg_type cmsg_data[]
> + * ------------ ------------ -------------------
> + * IPPROTO_SCTP SCTP_RCVINFO struct sctp_rcvinfo
> + *
> + */
> +struct sctp_rcvinfo {
> + __u16 rcv_sid;
> + __u16 rcv_ssn;
> + __u16 rcv_flags;
> + __u32 rcv_ppid;
> + __u32 rcv_tsn;
> + __u32 rcv_cumtsn;
> + __u32 rcv_context;
> + sctp_assoc_t rcv_assoc_id;
> +};
> +
> +/*
> * sinfo_flags: 16 bits (unsigned integer)
> *
> * This field may contain any of the following flags and is composed of
> @@ -184,6 +205,8 @@ typedef enum sctp_cmsg_type {
> #define SCTP_INIT SCTP_INIT
> SCTP_SNDRCV, /* 5.2.2 SCTP Header Information Structure */
> #define SCTP_SNDRCV SCTP_SNDRCV
> + SCTP_RCVINFO,
> +#define SCTP_RCVINFO SCTP_RCVINFO
> } sctp_cmsg_t;
>
> /*
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 1f3281b..aee161b 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -2094,6 +2094,12 @@ static int sctp_recvmsg(struct kiocb *iocb, struct sock *sk,
> sp->pf->skb_msgname(skb, msg->msg_name, addr_len);
> }
>
> +
> + /* Check if SCTP_RCVINFO should be included */
> + if(sp->recvrcvinfo){
> + sctp_ulpevent_read_rcvinfo(event, msg);
> + }
> +
> /* Check if we allow SCTP_SNDRCVINFO. */
> if (sp->subscribe.sctp_data_io_event)
> sctp_ulpevent_read_sndrcvinfo(event, msg);
> diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
> index 81089ed..d1b9a02 100644
> --- a/net/sctp/ulpevent.c
> +++ b/net/sctp/ulpevent.c
> @@ -900,6 +900,97 @@ __u16 sctp_ulpevent_get_notification_type(const struct sctp_ulpevent *event)
> return notification->sn_header.sn_type;
> }
>
> +void sctp_ulpevent_read_rcvinfo(const struct sctp_ulpevent *event,
> + struct msghdr *msghdr)
> +{
> + struct sctp_rcvinfo rinfo;
> +
> + if (sctp_ulpevent_is_notification(event)){
> + return;
> + }
> +
As David Laight mentioned, the spec defines sctp_rcvinfo with a hole in it.
To prevent passing kernel stack data to user space, you need to zero-out the
data first.
-vlad
> + /* Sockets API Extensions for SCTP
> + * Section 5.3.5 SCTP Receive Information Structure (SCTP_SNDRCV)
> + *
> + * rcv_sid: 16 bits (unsigned integer)
> + *
> + * The SCTP stack places the message's stream number in this
> + * value.
> + */
> + rinfo.rcv_sid = event->stream;
> +
> + /* rcv_ssn: 16 bits (unsigned integer)
> + * This value contains the stream sequence number that the
> + * remote endpoint placed in the DATA chunk. For fragmented
> + * messages, this is the same number for all deliveries of the
> + * message (if more than one recvmsg() is needed to read
> + * the message)
> + */
> + rinfo.rcv_ssn = event->ssn;
> +
> +
> + /* rcv_ppid: 32 bits (unsigned integer)
> + *
> + * This value is the same information that was passed by the
> + * upper layer in the peer application. Please note that the SCTP
> + * stack performs no byte order modification of this field.
> + * For example, if the DATA chunk has to contain a given
> + * value in network byte order, the SCTP user has to perform the
> + * ntohl() computation.
> + */
> + rinfo.rcv_ppid = event->ppid;
> +
> + /* rcv_flags: 16 bits (unsigned integer)
> + *
> + * This field may contain any of the following flags and is composed of
> + * a bitwise OR of these values.
> + *
> + * recvmsg() flags:
> + *
> + * SCTP_UNORDERED - This flag is present when the message was sent
> + * non-ordered.
> + */
> +
> + rinfo.rcv_flags = event->flags;
> +
> + /* rcv_tsn: 32 bits (unsigned integer)
> + *
> + * This field holds a TSN that was assigned to one of the SCTP
> + * DATA chunks.
> + */
> + rinfo.rcv_tsn = event->tsn;
> +
> + /* rcv_cumtsn: 32 bits (unsigned integer)
> + *
> + * This field will hold the current cumulative TSN as known
> + * by the underlying SCTP layer.
> + */
> + rinfo.rcv_cumtsn = event->cumtsn;
> +
> + /* rcv_assoc_id: sizeof (sctp_assoc_t)
> + *
> + * The association handle field, sinfo_assoc_id, holds the identifier
> + * for the association announced in the COMMUNICATION_UP notification.
> + * All notifications for a given association have the same identifier.
> + * Ignored for one-to-one style sockets.
> + */
> + rinfo.rcv_assoc_id = sctp_assoc2id(event->asoc);
> +
> + /* rcv_context: 32 bits (unsigned integer)
> + *
> + * This value is an opaque 32-bit context datum that was
> + * set by the user with the SCTP_CONTEXT socket option. This
> + * value is passed back to the upper layer if an error occurs on
> + * the send of a message and is retrieved with each undelivered
> + * message.
> + */
> + rinfo.rcv_context = event->asoc->default_rcv_context;
> +
> + put_cmsg(msghdr, IPPROTO_SCTP, SCTP_RCVINFO,
> + sizeof(struct sctp_rcvinfo), (void *)&rinfo);
> +}
> +
> +
> /* Copy out the sndrcvinfo into a msghdr. */
> void sctp_ulpevent_read_sndrcvinfo(const struct sctp_ulpevent *event,
> struct msghdr *msghdr)
>
--
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