sctp: implement prsctp TTL policy

prsctp TTL policy is a policy to abandon chunks when they expire
at the specific time in local stack. It's similar with expires_at
in struct sctp_datamsg.

This patch uses sinfo->sinfo_timetolive to set the specific time for
TTL policy. sinfo->sinfo_timetolive is also used for msg->expires_at.
So if prsctp_enable or TTL policy is not enabled, msg->expires_at
still works as before.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -602,6 +602,16 @@ struct sctp_chunk {
 	/* This needs to be recoverable for SCTP_SEND_FAILED events. */
 	struct sctp_sndrcvinfo sinfo;
 
+	/* We use this field to record param for prsctp policies,
+	 * for TTL policy, it is the time_to_drop of this chunk,
+	 * for RTX policy, it is the max_sent_count of this chunk,
+	 * for PRIO policy, it is the priority of this chunk.
+	 */
+	unsigned long prsctp_param;
+
+	/* How many times this chunk have been sent, for prsctp RTX policy */
+	int sent_count;
+
 	/* Which association does this belong to?  */
 	struct sctp_association *asoc;
 

net/sctp/chunk.c

@@ -335,6 +335,8 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 /* Check whether this message has expired. */
 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 {
+	if (!chunk->asoc->prsctp_enable ||
+	    !SCTP_PR_POLICY(chunk->sinfo.sinfo_flags)) {
 		struct sctp_datamsg *msg = chunk->msg;
 
 		if (!msg->can_abandon)
@@ -346,6 +348,18 @@ int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 		return 0;
 	}
 
+	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
+	    time_after(jiffies, chunk->prsctp_param)) {
+		if (chunk->sent_count)
+			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
+		else
+			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
+		return 1;
+	}
+
+	return 0;
+}
+
 /* This chunk (and consequently entire message) has failed in its sending. */
 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
 {

net/sctp/output.c

@@ -316,6 +316,8 @@ static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet,
 		packet->has_data = 1;
 		/* timestamp the chunk for rtx purposes */
 		chunk->sent_at = jiffies;
+		/* Mainly used for prsctp RTX policy */
+		chunk->sent_count++;
 		break;
 	case SCTP_CID_COOKIE_ECHO:
 		packet->has_cookie_echo = 1;

net/sctp/sm_make_chunk.c

@@ -711,6 +711,17 @@ struct sctp_chunk *sctp_make_ecne(const struct sctp_association *asoc,
 	return retval;
 }
 
+static void sctp_set_prsctp_policy(struct sctp_chunk *chunk,
+				   const struct sctp_sndrcvinfo *sinfo)
+{
+	if (!chunk->asoc->prsctp_enable)
+		return;
+
+	if (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
+		chunk->prsctp_param =
+			jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
+}
+
 /* Make a DATA chunk for the given association from the provided
  * parameters.  However, do not populate the data payload.
  */
@@ -744,6 +755,7 @@ struct sctp_chunk *sctp_make_datafrag_empty(struct sctp_association *asoc,
 
 	retval->subh.data_hdr = sctp_addto_chunk(retval, sizeof(dp), &dp);
 	memcpy(&retval->sinfo, sinfo, sizeof(struct sctp_sndrcvinfo));
+	sctp_set_prsctp_policy(retval, sinfo);
 
 nodata:
 	return retval;

net/sctp/socket.c

@@ -7099,7 +7099,7 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
 
 			if (cmsgs->srinfo->sinfo_flags &
 			    ~(SCTP_UNORDERED | SCTP_ADDR_OVER |
-			      SCTP_SACK_IMMEDIATELY |
+			      SCTP_SACK_IMMEDIATELY | SCTP_PR_SCTP_MASK |
 			      SCTP_ABORT | SCTP_EOF))
 				return -EINVAL;
 			break;
@@ -7123,7 +7123,7 @@ static int sctp_msghdr_parse(const struct msghdr *msg, sctp_cmsgs_t *cmsgs)
 
 			if (cmsgs->sinfo->snd_flags &
 			    ~(SCTP_UNORDERED | SCTP_ADDR_OVER |
-			      SCTP_SACK_IMMEDIATELY |
+			      SCTP_SACK_IMMEDIATELY | SCTP_PR_SCTP_MASK |
 			      SCTP_ABORT | SCTP_EOF))
 				return -EINVAL;
 			break;