net: sctp: implement rfc6458, 5.3.6. SCTP_NXTINFO cmsg support
This patch implements section 5.3.6. of RFC6458, that is, support
for 'SCTP Next Receive Information Structure' (SCTP_NXTINFO) which
is placed into ancillary data cmsghdr structure for each recvmsg()
call, if this information is already available when delivering the
current message.
This option can be enabled/disabled via setsockopt(2) on SOL_SCTP
level by setting an int value with 1/0 for SCTP_RECVNXTINFO in
user space applications as per RFC6458, section 8.1.30.
The sctp_nxtinfo structure is defined as per RFC as below ...
struct sctp_nxtinfo {
uint16_t nxt_sid;
uint16_t nxt_flags;
uint32_t nxt_ppid;
uint32_t nxt_length;
sctp_assoc_t nxt_assoc_id;
};
... and provided under cmsg_level IPPROTO_SCTP, cmsg_type
SCTP_NXTINFO, while cmsg_data[] contains struct sctp_nxtinfo.
Joint work with Daniel Borkmann.
Signed-off-by: Geir Ola Vaagland <geirola@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 9c19388..9bca87e 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2060,8 +2060,6 @@
* flags - flags sent or received with the user message, see Section
* 5 for complete description of the flags.
*/
-static struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int, int *);
-
static int sctp_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t len, int noblock,
int flags, int *addr_len)
@@ -2112,6 +2110,9 @@
sp->pf->skb_msgname(skb, msg->msg_name, addr_len);
}
+ /* Check if we allow SCTP_NXTINFO. */
+ if (sp->recvnxtinfo)
+ sctp_ulpevent_read_nxtinfo(event, msg, sk);
/* Check if we allow SCTP_RCVINFO. */
if (sp->recvrcvinfo)
sctp_ulpevent_read_rcvinfo(event, msg);
@@ -3611,6 +3612,22 @@
return 0;
}
+static int sctp_setsockopt_recvnxtinfo(struct sock *sk,
+ char __user *optval,
+ unsigned int optlen)
+{
+ int val;
+
+ if (optlen < sizeof(int))
+ return -EINVAL;
+ if (get_user(val, (int __user *) optval))
+ return -EFAULT;
+
+ sctp_sk(sk)->recvnxtinfo = (val == 0) ? 0 : 1;
+
+ return 0;
+}
+
/* API 6.2 setsockopt(), getsockopt()
*
* Applications use setsockopt() and getsockopt() to set or retrieve
@@ -3765,6 +3782,9 @@
case SCTP_RECVRCVINFO:
retval = sctp_setsockopt_recvrcvinfo(sk, optval, optlen);
break;
+ case SCTP_RECVNXTINFO:
+ retval = sctp_setsockopt_recvnxtinfo(sk, optval, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
@@ -4012,6 +4032,7 @@
sp->nodelay = 0;
sp->recvrcvinfo = 0;
+ sp->recvnxtinfo = 0;
/* Enable by default. */
sp->v4mapped = 1;
@@ -5814,6 +5835,26 @@
return 0;
}
+static int sctp_getsockopt_recvnxtinfo(struct sock *sk, int len,
+ char __user *optval,
+ int __user *optlen)
+{
+ int val = 0;
+
+ if (len < sizeof(int))
+ return -EINVAL;
+
+ len = sizeof(int);
+ if (sctp_sk(sk)->recvnxtinfo)
+ val = 1;
+ if (put_user(len, optlen))
+ return -EFAULT;
+ if (copy_to_user(optval, &val, len))
+ return -EFAULT;
+
+ return 0;
+}
+
static int sctp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
{
@@ -5960,6 +6001,9 @@
case SCTP_RECVRCVINFO:
retval = sctp_getsockopt_recvrcvinfo(sk, len, optval, optlen);
break;
+ case SCTP_RECVNXTINFO:
+ retval = sctp_getsockopt_recvnxtinfo(sk, len, optval, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
@@ -6602,8 +6646,8 @@
* Note: This is pretty much the same routine as in core/datagram.c
* with a few changes to make lksctp work.
*/
-static struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags,
- int noblock, int *err)
+struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags,
+ int noblock, int *err)
{
int error;
struct sk_buff *skb;
