git: 989453da0589 - main - sctp: cleanup the SCTP_MAXSEG socket option.
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Date: Mon, 27 Dec 2021 22:43:40 UTC
The branch main has been updated by tuexen:
URL: https://cgit.FreeBSD.org/src/commit/?id=989453da0589b8dc5c1948fd81f986a37ea385eb
commit 989453da0589b8dc5c1948fd81f986a37ea385eb
Author: Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2021-12-27 22:40:31 +0000
Commit: Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2021-12-27 22:40:31 +0000
sctp: cleanup the SCTP_MAXSEG socket option.
This patch makes the handling of the SCTP_MAXSEG socket option
compliant with RFC 6458 (SCTP socket API) and fixes an issue
found by syzkaller.
Reported by: syzbot+a2791b89ab99121e3333@syzkaller.appspotmail.com
MFC after: 3 days
---
sys/netinet/sctp_constants.h | 2 -
sys/netinet/sctp_output.c | 93 ++++++++++++++++++++++++--------------------
sys/netinet/sctp_output.h | 2 +-
sys/netinet/sctp_pcb.c | 2 +-
sys/netinet/sctp_usrreq.c | 37 +++---------------
sys/netinet/sctputil.c | 2 +-
6 files changed, 59 insertions(+), 79 deletions(-)
diff --git a/sys/netinet/sctp_constants.h b/sys/netinet/sctp_constants.h
index 1ff3f3918ef6..66f2cca5ab6d 100644
--- a/sys/netinet/sctp_constants.h
+++ b/sys/netinet/sctp_constants.h
@@ -673,8 +673,6 @@ __FBSDID("$FreeBSD$");
/* amount peer is obligated to have in rwnd or I will abort */
#define SCTP_MIN_RWND 1500
-#define SCTP_DEFAULT_MAXSEGMENT 65535
-
#define SCTP_CHUNK_BUFFER_SIZE 512
#define SCTP_PARAM_BUFFER_SIZE 512
diff --git a/sys/netinet/sctp_output.c b/sys/netinet/sctp_output.c
index 65767f9f73a9..f6597bc6cbdc 100644
--- a/sys/netinet/sctp_output.c
+++ b/sys/netinet/sctp_output.c
@@ -6217,43 +6217,48 @@ sctp_prune_prsctp(struct sctp_tcb *stcb,
} /* if enabled in asoc */
}
-int
-sctp_get_frag_point(struct sctp_tcb *stcb,
- struct sctp_association *asoc)
+uint32_t
+sctp_get_frag_point(struct sctp_tcb *stcb)
{
- int siz, ovh;
+ struct sctp_association *asoc;
+ uint32_t frag_point, overhead;
- /*
- * For endpoints that have both v6 and v4 addresses we must reserve
- * room for the ipv6 header, for those that are only dealing with V4
- * we use a larger frag point.
- */
+ asoc = &stcb->asoc;
+ /* Consider IP header and SCTP common header. */
if (stcb->sctp_ep->sctp_flags & SCTP_PCB_FLAGS_BOUND_V6) {
- ovh = SCTP_MIN_OVERHEAD;
+ overhead = SCTP_MIN_OVERHEAD;
} else {
- ovh = SCTP_MIN_V4_OVERHEAD;
+ overhead = SCTP_MIN_V4_OVERHEAD;
}
- ovh += SCTP_DATA_CHUNK_OVERHEAD(stcb);
- if (stcb->asoc.sctp_frag_point > asoc->smallest_mtu)
- siz = asoc->smallest_mtu - ovh;
- else
- siz = (stcb->asoc.sctp_frag_point - ovh);
- /*
- * if (siz > (MCLBYTES-sizeof(struct sctp_data_chunk))) {
- */
- /* A data chunk MUST fit in a cluster */
- /* siz = (MCLBYTES - sizeof(struct sctp_data_chunk)); */
- /* } */
-
- /* adjust for an AUTH chunk if DATA requires auth */
- if (sctp_auth_is_required_chunk(SCTP_DATA, stcb->asoc.peer_auth_chunks))
- siz -= sctp_get_auth_chunk_len(stcb->asoc.peer_hmac_id);
+ /* Consider DATA/IDATA chunk header and AUTH header, if needed. */
+ if (asoc->idata_supported) {
+ overhead += sizeof(struct sctp_idata_chunk);
+ if (sctp_auth_is_required_chunk(SCTP_IDATA, asoc->peer_auth_chunks)) {
+ overhead += sctp_get_auth_chunk_len(asoc->peer_hmac_id);
+ }
+ } else {
+ overhead += sizeof(struct sctp_idata_chunk);
+ if (sctp_auth_is_required_chunk(SCTP_DATA, asoc->peer_auth_chunks)) {
+ overhead += sctp_get_auth_chunk_len(asoc->peer_hmac_id);
+ }
+ }
+ /* Consider padding. */
+ if (asoc->smallest_mtu % 4) {
+ overhead += (asoc->smallest_mtu % 4);
+ }
+ KASSERT(overhead % 4 == 0,
+ ("overhead (%u) not a multiple of 4", overhead));
+ KASSERT(asoc->smallest_mtu > overhead,
+ ("Association MTU (%u) too small for overhead (%u)",
+ asoc->smallest_mtu, overhead));
- if (siz % 4) {
- /* make it an even word boundary please */
- siz -= (siz % 4);
+ frag_point = asoc->smallest_mtu - overhead;
+ /* Honor MAXSEG socket option. */
+ if ((asoc->sctp_frag_point > 0) &&
+ (asoc->sctp_frag_point < frag_point)) {
+ frag_point = asoc->sctp_frag_point;
}
- return (siz);
+ return (frag_point);
}
static void
@@ -6571,7 +6576,8 @@ sctp_med_chunk_output(struct sctp_inpcb *inp,
int *num_out,
int *reason_code,
int control_only, int from_where,
- struct timeval *now, int *now_filled, int frag_point, int so_locked);
+ struct timeval *now, int *now_filled,
+ uint32_t frag_point, int so_locked);
static void
sctp_sendall_iterator(struct sctp_inpcb *inp, struct sctp_tcb *stcb, void *ptr,
@@ -6740,13 +6746,13 @@ sctp_sendall_iterator(struct sctp_inpcb *inp, struct sctp_tcb *stcb, void *ptr,
if (do_chunk_output)
sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_USR_SEND, SCTP_SO_NOT_LOCKED);
else if (added_control) {
- int num_out, reason, now_filled = 0;
struct timeval now;
- int frag_point;
+ int num_out, reason, now_filled = 0;
- frag_point = sctp_get_frag_point(stcb, &stcb->asoc);
(void)sctp_med_chunk_output(inp, stcb, &stcb->asoc, &num_out,
- &reason, 1, 1, &now, &now_filled, frag_point, SCTP_SO_NOT_LOCKED);
+ &reason, 1, 1, &now, &now_filled,
+ sctp_get_frag_point(stcb),
+ SCTP_SO_NOT_LOCKED);
}
no_chunk_output:
if (ret) {
@@ -7674,8 +7680,9 @@ out_of:
}
static void
-sctp_fill_outqueue(struct sctp_tcb *stcb, struct sctp_nets *net, int frag_point,
- int eeor_mode, int *quit_now, int so_locked)
+sctp_fill_outqueue(struct sctp_tcb *stcb, struct sctp_nets *net,
+ uint32_t frag_point, int eeor_mode, int *quit_now,
+ int so_locked)
{
struct sctp_association *asoc;
struct sctp_stream_out *strq;
@@ -7794,7 +7801,8 @@ sctp_med_chunk_output(struct sctp_inpcb *inp,
int *num_out,
int *reason_code,
int control_only, int from_where,
- struct timeval *now, int *now_filled, int frag_point, int so_locked)
+ struct timeval *now, int *now_filled,
+ uint32_t frag_point, int so_locked)
{
/**
* Ok this is the generic chunk service queue. we must do the
@@ -9975,7 +9983,7 @@ sctp_chunk_output(struct sctp_inpcb *inp,
struct timeval now;
int now_filled = 0;
int nagle_on;
- int frag_point = sctp_get_frag_point(stcb, &stcb->asoc);
+ uint32_t frag_point = sctp_get_frag_point(stcb);
int un_sent = 0;
int fr_done;
unsigned int tot_frs = 0;
@@ -13663,16 +13671,17 @@ skip_out_eof:
}
sctp_chunk_output(inp, stcb, SCTP_OUTPUT_FROM_USR_SEND, SCTP_SO_LOCKED);
} else if (some_on_control) {
- int num_out, reason, frag_point;
+ int num_out, reason;
/* Here we do control only */
if (hold_tcblock == 0) {
hold_tcblock = 1;
SCTP_TCB_LOCK(stcb);
}
- frag_point = sctp_get_frag_point(stcb, &stcb->asoc);
(void)sctp_med_chunk_output(inp, stcb, &stcb->asoc, &num_out,
- &reason, 1, 1, &now, &now_filled, frag_point, SCTP_SO_LOCKED);
+ &reason, 1, 1, &now, &now_filled,
+ sctp_get_frag_point(stcb),
+ SCTP_SO_LOCKED);
}
NET_EPOCH_EXIT(et);
SCTPDBG(SCTP_DEBUG_OUTPUT1, "USR Send complete qo:%d prw:%d unsent:%d tf:%d cooq:%d toqs:%d err:%d\n",
diff --git a/sys/netinet/sctp_output.h b/sys/netinet/sctp_output.h
index 7d2cdc4071d8..e6ee80c41f1a 100644
--- a/sys/netinet/sctp_output.h
+++ b/sys/netinet/sctp_output.h
@@ -117,7 +117,7 @@ void sctp_send_asconf(struct sctp_tcb *, struct sctp_nets *, int addr_locked);
void sctp_send_asconf_ack(struct sctp_tcb *);
-int sctp_get_frag_point(struct sctp_tcb *, struct sctp_association *);
+uint32_t sctp_get_frag_point(struct sctp_tcb *);
void sctp_toss_old_cookies(struct sctp_tcb *, struct sctp_association *);
diff --git a/sys/netinet/sctp_pcb.c b/sys/netinet/sctp_pcb.c
index b4a742c11629..7ad651ec377f 100644
--- a/sys/netinet/sctp_pcb.c
+++ b/sys/netinet/sctp_pcb.c
@@ -2422,7 +2422,7 @@ sctp_inpcb_alloc(struct socket *so, uint32_t vrf_id)
#endif
inp->sctp_associd_counter = 1;
inp->partial_delivery_point = SCTP_SB_LIMIT_RCV(so) >> SCTP_PARTIAL_DELIVERY_SHIFT;
- inp->sctp_frag_point = SCTP_DEFAULT_MAXSEGMENT;
+ inp->sctp_frag_point = 0;
inp->max_cwnd = 0;
inp->sctp_cmt_on_off = SCTP_BASE_SYSCTL(sctp_cmt_on_off);
inp->ecn_supported = (uint8_t)SCTP_BASE_SYSCTL(sctp_ecn_enable);
diff --git a/sys/netinet/sctp_usrreq.c b/sys/netinet/sctp_usrreq.c
index f218950feef9..bb84d3b7083f 100644
--- a/sys/netinet/sctp_usrreq.c
+++ b/sys/netinet/sctp_usrreq.c
@@ -2032,13 +2032,12 @@ flags_out:
case SCTP_MAXSEG:
{
struct sctp_assoc_value *av;
- int ovh;
SCTP_CHECK_AND_CAST(av, optval, struct sctp_assoc_value, *optsize);
SCTP_FIND_STCB(inp, stcb, av->assoc_id);
if (stcb) {
- av->assoc_value = sctp_get_frag_point(stcb, &stcb->asoc);
+ av->assoc_value = stcb->asoc.sctp_frag_point;
SCTP_TCB_UNLOCK(stcb);
} else {
if ((inp->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) ||
@@ -2046,15 +2045,7 @@ flags_out:
((inp->sctp_flags & SCTP_PCB_FLAGS_UDPTYPE) &&
(av->assoc_id == SCTP_FUTURE_ASSOC))) {
SCTP_INP_RLOCK(inp);
- if (inp->sctp_flags & SCTP_PCB_FLAGS_BOUND_V6) {
- ovh = SCTP_MED_OVERHEAD;
- } else {
- ovh = SCTP_MED_V4_OVERHEAD;
- }
- if (inp->sctp_frag_point >= SCTP_DEFAULT_MAXSEGMENT)
- av->assoc_value = 0;
- else
- av->assoc_value = inp->sctp_frag_point - ovh;
+ av->assoc_value = inp->sctp_frag_point;
SCTP_INP_RUNLOCK(inp);
} else {
SCTP_LTRACE_ERR_RET(inp, NULL, NULL, SCTP_FROM_SCTP_USRREQ, EINVAL);
@@ -2623,7 +2614,7 @@ flags_out:
stcb->asoc.cnt_on_all_streams);
sstat->sstat_instrms = stcb->asoc.streamincnt;
sstat->sstat_outstrms = stcb->asoc.streamoutcnt;
- sstat->sstat_fragmentation_point = sctp_get_frag_point(stcb, &stcb->asoc);
+ sstat->sstat_fragmentation_point = sctp_get_frag_point(stcb);
net = stcb->asoc.primary_destination;
if (net != NULL) {
memcpy(&sstat->sstat_primary.spinfo_address,
@@ -4977,22 +4968,12 @@ sctp_setopt(struct socket *so, int optname, void *optval, size_t optsize,
case SCTP_MAXSEG:
{
struct sctp_assoc_value *av;
- int ovh;
SCTP_CHECK_AND_CAST(av, optval, struct sctp_assoc_value, optsize);
SCTP_FIND_STCB(inp, stcb, av->assoc_id);
- if (inp->sctp_flags & SCTP_PCB_FLAGS_BOUND_V6) {
- ovh = SCTP_MED_OVERHEAD;
- } else {
- ovh = SCTP_MED_V4_OVERHEAD;
- }
if (stcb) {
- if (av->assoc_value) {
- stcb->asoc.sctp_frag_point = (av->assoc_value + ovh);
- } else {
- stcb->asoc.sctp_frag_point = SCTP_DEFAULT_MAXSEGMENT;
- }
+ stcb->asoc.sctp_frag_point = av->assoc_value;
SCTP_TCB_UNLOCK(stcb);
} else {
if ((inp->sctp_flags & SCTP_PCB_FLAGS_TCPTYPE) ||
@@ -5000,15 +4981,7 @@ sctp_setopt(struct socket *so, int optname, void *optval, size_t optsize,
((inp->sctp_flags & SCTP_PCB_FLAGS_UDPTYPE) &&
(av->assoc_id == SCTP_FUTURE_ASSOC))) {
SCTP_INP_WLOCK(inp);
- /*
- * FIXME MT: I think this is not in
- * tune with the API ID
- */
- if (av->assoc_value) {
- inp->sctp_frag_point = (av->assoc_value + ovh);
- } else {
- inp->sctp_frag_point = SCTP_DEFAULT_MAXSEGMENT;
- }
+ inp->sctp_frag_point = av->assoc_value;
SCTP_INP_WUNLOCK(inp);
} else {
SCTP_LTRACE_ERR_RET(inp, NULL, NULL, SCTP_FROM_SCTP_USRREQ, EINVAL);
diff --git a/sys/netinet/sctputil.c b/sys/netinet/sctputil.c
index 6c58ad47f274..df3768ca2a35 100644
--- a/sys/netinet/sctputil.c
+++ b/sys/netinet/sctputil.c
@@ -1248,7 +1248,7 @@ sctp_init_asoc(struct sctp_inpcb *inp, struct sctp_tcb *stcb,
asoc->my_rwnd = max(SCTP_SB_LIMIT_RCV(inp->sctp_socket), SCTP_MINIMAL_RWND);
asoc->peers_rwnd = SCTP_SB_LIMIT_RCV(inp->sctp_socket);
- asoc->smallest_mtu = inp->sctp_frag_point;
+ asoc->smallest_mtu = 0;
asoc->minrto = inp->sctp_ep.sctp_minrto;
asoc->maxrto = inp->sctp_ep.sctp_maxrto;