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Commit f68b2e05 authored by Vlad Yasevich's avatar Vlad Yasevich
Browse files

sctp: Fix SCTP_MAXSEG socket option to comply to spec. 



We had a bug that we never stored the user-defined value for
MAXSEG when setting the value on an association.  Thus future
PMTU events ended up re-writing the frag point and increasing
it past user limit.  Additionally, when setting the option on
the socket/endpoint, we effect all current associations, which
is against spec.

Now, we store the user 'maxseg' value along with the computed
'frag_point'.  We inherit 'maxseg' from the socket at association
creation and use it as an upper limit for 'frag_point' when its
set.

Signed-off-by: default avatarVlad Yasevich <vladislav.yasevich@hp.com>
parent cb95ea32

include/net/sctp/sctp.h

+4 −3
Original line number Diff line number Diff line
@@ -486,15 +486,16 @@ static inline __s32 sctp_jitter(__u32 rto) 
}



/* Break down data chunks at this point.  */

static inline int sctp_frag_point(const struct sctp_sock *sp, int pmtu)

static inline int sctp_frag_point(const struct sctp_association *asoc, int pmtu)

{

	struct sctp_sock *sp = sctp_sk(asoc->base.sk);

	int frag = pmtu;



	frag -= sp->pf->af->net_header_len;

	frag -= sizeof(struct sctphdr) + sizeof(struct sctp_data_chunk);



	if (sp->user_frag)

		frag = min_t(int, frag, sp->user_frag);

	if (asoc->user_frag)

		frag = min_t(int, frag, asoc->user_frag);



	frag = min_t(int, frag, SCTP_MAX_CHUNK_LEN);

include/net/sctp/structs.h

+1 −0
Original line number Diff line number Diff line
@@ -1763,6 +1763,7 @@ struct sctp_association { 


	/* The message size at which SCTP fragmentation will occur. */

	__u32 frag_point;

	__u32 user_frag;



	/* Counter used to count INIT errors. */

	int init_err_counter;

net/sctp/associola.c

+3 −3
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ static struct sctp_association *sctp_association_init(struct sctp_association *a 
	asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)

					* 1000;

	asoc->frag_point = 0;

	asoc->user_frag = sp->user_frag;



	/* Set the association max_retrans and RTO values from the

	 * socket values.
@@ -674,7 +675,7 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc, 
			  "%d\n", asoc, asoc->pathmtu);

	peer->pmtu_pending = 0;



	asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);

	asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);



	/* The asoc->peer.port might not be meaningful yet, but

	 * initialize the packet structure anyway.
@@ -1330,9 +1331,8 @@ void sctp_assoc_sync_pmtu(struct sctp_association *asoc) 
	}



	if (pmtu) {

		struct sctp_sock *sp = sctp_sk(asoc->base.sk);

		asoc->pathmtu = pmtu;

		asoc->frag_point = sctp_frag_point(sp, pmtu);

		asoc->frag_point = sctp_frag_point(asoc, pmtu);

	}



	SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",

net/sctp/socket.c

+3 −8
Original line number Diff line number Diff line
@@ -2243,7 +2243,7 @@ static int sctp_apply_peer_addr_params(struct sctp_paddrparams *params, 
			sctp_assoc_sync_pmtu(asoc);

		} else if (asoc) {

			asoc->pathmtu = params->spp_pathmtu;

			sctp_frag_point(sp, params->spp_pathmtu);

			sctp_frag_point(asoc, params->spp_pathmtu);

		} else {

			sp->pathmtu = params->spp_pathmtu;

		}
@@ -2880,15 +2880,10 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, int optl 
			val -= sizeof(struct sctphdr) +

					sizeof(struct sctp_data_chunk);

		}



		asoc->frag_point = val;

		asoc->user_frag = val;

		asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);

	} else {

		sp->user_frag = val;



		/* Update the frag_point of the existing associations. */

		list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {

			asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);

		}

	}



	return 0;