Convert all IPv4 and IPv6 multicast memberships into using a STAILQ

instead of a linear array.

The multicast memberships for the inpcb structure are protected by a
non-sleepable lock, INP_WLOCK(), which needs to be dropped when
calling the underlying possibly sleeping if_ioctl() method. When using
a linear array to keep track of multicast memberships, the computed
memory location of the multicast filter may suddenly change, due to
concurrent insertion or removal of elements in the linear array. This
in turn leads to various invalid memory access issues and kernel
panics.

To avoid this problem, put all multicast memberships on a STAILQ based
list. Then the memory location of the IPv4 and IPv6 multicast filters
become fixed during their lifetime and use after free and memory leak
issues are easier to track, for example by: vmstat -m | grep multi

All list manipulation has been factored into inline functions
including some macros, to easily allow for a future hash-list
implementation, if needed.

This patch has been tested by pho@ .

Differential Revision: https://reviews.freebsd.org/D20080
Reviewed by:	markj @
MFC after:	1 week
Sponsored by:	Mellanox Technologies

1 files changed, 163 insertions, 270 deletions

diff --git a/sys/netinet/in_mcast.c b/sys/netinet/in_mcast.c
index 2980c1a463ca..ac5c6a03ab54 100644
--- a/sys/netinet/in_mcast.c
+++ b/sys/netinet/in_mcast.c
@@ -94,7 +94,9 @@ static MALLOC_DEFINE(M_IPMSOURCE, "ip_msource",
 
 /*
  * Locking:
- * - Lock order is: Giant, INP_WLOCK, IN_MULTI_LIST_LOCK, IGMP_LOCK, IF_ADDR_LOCK.
+ *
+ * - Lock order is: Giant, IN_MULTI_LOCK, INP_WLOCK,
+ *   IN_MULTI_LIST_LOCK, IGMP_LOCK, IF_ADDR_LOCK.
  * - The IF_ADDR_LOCK is implicitly taken by inm_lookup() earlier, however
  *   it can be taken by code in net/if.c also.
  * - ip_moptions and in_mfilter are covered by the INP_WLOCK.
@@ -144,12 +146,11 @@ static int	imf_prune(struct in_mfilter *, const struct sockaddr_in *);
 static void	imf_purge(struct in_mfilter *);
 static void	imf_rollback(struct in_mfilter *);
 static void	imf_reap(struct in_mfilter *);
-static int	imo_grow(struct ip_moptions *);
-static size_t	imo_match_group(const struct ip_moptions *,
+static struct in_mfilter *
+		imo_match_group(const struct ip_moptions *,
 		    const struct ifnet *, const struct sockaddr *);
 static struct in_msource *
-		imo_match_source(const struct ip_moptions *, const size_t,
-		    const struct sockaddr *);
+		imo_match_source(struct in_mfilter *, const struct sockaddr *);
 static void	ims_merge(struct ip_msource *ims,
 		    const struct in_msource *lims, const int rollback);
 static int	in_getmulti(struct ifnet *, const struct in_addr *,
@@ -333,6 +334,26 @@ imf_init(struct in_mfilter *imf, const int st0, const int st1)
 	imf->imf_st[1] = st1;
 }
 
+struct in_mfilter *
+ip_mfilter_alloc(const int mflags, const int st0, const int st1)
+{
+	struct in_mfilter *imf;
+
+	imf = malloc(sizeof(*imf), M_INMFILTER, mflags);
+	if (imf != NULL)
+		imf_init(imf, st0, st1);
+
+	return (imf);
+}
+
+void
+ip_mfilter_free(struct in_mfilter *imf)
+{
+
+	imf_purge(imf);
+	free(imf, M_INMFILTER);
+}
+
 /*
  * Function for looking up an in_multi record for an IPv4 multicast address
  * on a given interface. ifp must be valid. If no record found, return NULL.
@@ -379,89 +400,30 @@ inm_lookup(struct ifnet *ifp, const struct in_addr ina)
 }
 
 /*
- * Resize the ip_moptions vector to the next power-of-two minus 1.
- * May be called with locks held; do not sleep.
- */
-static int
-imo_grow(struct ip_moptions *imo)
-{
-	struct in_multi		**nmships;
-	struct in_multi		**omships;
-	struct in_mfilter	 *nmfilters;
-	struct in_mfilter	 *omfilters;
-	size_t			  idx;
-	size_t			  newmax;
-	size_t			  oldmax;
-
-	nmships = NULL;
-	nmfilters = NULL;
-	omships = imo->imo_membership;
-	omfilters = imo->imo_mfilters;
-	oldmax = imo->imo_max_memberships;
-	newmax = ((oldmax + 1) * 2) - 1;
-
-	if (newmax <= IP_MAX_MEMBERSHIPS) {
-		nmships = (struct in_multi **)realloc(omships,
-		    sizeof(struct in_multi *) * newmax, M_IPMOPTS, M_NOWAIT);
-		nmfilters = (struct in_mfilter *)realloc(omfilters,
-		    sizeof(struct in_mfilter) * newmax, M_INMFILTER, M_NOWAIT);
-		if (nmships != NULL && nmfilters != NULL) {
-			/* Initialize newly allocated source filter heads. */
-			for (idx = oldmax; idx < newmax; idx++) {
-				imf_init(&nmfilters[idx], MCAST_UNDEFINED,
-				    MCAST_EXCLUDE);
-			}
-			imo->imo_max_memberships = newmax;
-			imo->imo_membership = nmships;
-			imo->imo_mfilters = nmfilters;
-		}
-	}
-
-	if (nmships == NULL || nmfilters == NULL) {
-		if (nmships != NULL)
-			free(nmships, M_IPMOPTS);
-		if (nmfilters != NULL)
-			free(nmfilters, M_INMFILTER);
-		return (ETOOMANYREFS);
-	}
-
-	return (0);
-}
-
-/*
  * Find an IPv4 multicast group entry for this ip_moptions instance
  * which matches the specified group, and optionally an interface.
  * Return its index into the array, or -1 if not found.
  */
-static size_t
+static struct in_mfilter *
 imo_match_group(const struct ip_moptions *imo, const struct ifnet *ifp,
     const struct sockaddr *group)
 {
 	const struct sockaddr_in *gsin;
-	struct in_multi	**pinm;
-	int		  idx;
-	int		  nmships;
+	struct in_mfilter *imf;
+	struct in_multi	*inm;
 
 	gsin = (const struct sockaddr_in *)group;
 
-	/* The imo_membership array may be lazy allocated. */
-	if (imo->imo_membership == NULL || imo->imo_num_memberships == 0)
-		return (-1);
-
-	nmships = imo->imo_num_memberships;
-	pinm = &imo->imo_membership[0];
-	for (idx = 0; idx < nmships; idx++, pinm++) {
-		if (*pinm == NULL)
+	IP_MFILTER_FOREACH(imf, &imo->imo_head) {
+		inm = imf->imf_inm;
+		if (inm == NULL)
 			continue;
-		if ((ifp == NULL || ((*pinm)->inm_ifp == ifp)) &&
-		    in_hosteq((*pinm)->inm_addr, gsin->sin_addr)) {
+		if ((ifp == NULL || (inm->inm_ifp == ifp)) &&
+		    in_hosteq(inm->inm_addr, gsin->sin_addr)) {
 			break;
 		}
 	}
-	if (idx >= nmships)
-		idx = -1;
-
-	return (idx);
+	return (imf);
 }
 
 /*
@@ -472,22 +434,13 @@ imo_match_group(const struct ip_moptions *imo, const struct ifnet *ifp,
  * it exists, which may not be the desired behaviour.
  */
 static struct in_msource *
-imo_match_source(const struct ip_moptions *imo, const size_t gidx,
-    const struct sockaddr *src)
+imo_match_source(struct in_mfilter *imf, const struct sockaddr *src)
 {
 	struct ip_msource	 find;
-	struct in_mfilter	*imf;
 	struct ip_msource	*ims;
 	const sockunion_t	*psa;
 
 	KASSERT(src->sa_family == AF_INET, ("%s: !AF_INET", __func__));
-	KASSERT(gidx != -1 && gidx < imo->imo_num_memberships,
-	    ("%s: invalid index %d\n", __func__, (int)gidx));
-
-	/* The imo_mfilters array may be lazy allocated. */
-	if (imo->imo_mfilters == NULL)
-		return (NULL);
-	imf = &imo->imo_mfilters[gidx];
 
 	/* Source trees are keyed in host byte order. */
 	psa = (const sockunion_t *)src;
@@ -507,14 +460,14 @@ int
 imo_multi_filter(const struct ip_moptions *imo, const struct ifnet *ifp,
     const struct sockaddr *group, const struct sockaddr *src)
 {
-	size_t gidx;
+	struct in_mfilter *imf;
 	struct in_msource *ims;
 	int mode;
 
 	KASSERT(ifp != NULL, ("%s: null ifp", __func__));
 
-	gidx = imo_match_group(imo, ifp, group);
-	if (gidx == -1)
+	imf = imo_match_group(imo, ifp, group);
+	if (imf == NULL)
 		return (MCAST_NOTGMEMBER);
 
 	/*
@@ -526,8 +479,8 @@ imo_multi_filter(const struct ip_moptions *imo, const struct ifnet *ifp,
 	 * NOTE: We are comparing group state here at IGMP t1 (now)
 	 * with socket-layer t0 (since last downcall).
 	 */
-	mode = imo->imo_mfilters[gidx].imf_st[1];
-	ims = imo_match_source(imo, gidx, src);
+	mode = imf->imf_st[1];
+	ims = imo_match_source(imf, src);
 
 	if ((ims == NULL && mode == MCAST_INCLUDE) ||
 	    (ims != NULL && ims->imsl_st[0] != mode))
@@ -1452,7 +1405,6 @@ inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 	struct ip_moptions		*imo;
 	struct in_msource		*ims;
 	struct in_multi			*inm;
-	size_t				 idx;
 	uint16_t			 fmode;
 	int				 error, doblock;
 
@@ -1531,20 +1483,18 @@ inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 	if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
 		return (EINVAL);
 
+	IN_MULTI_LOCK();
+
 	/*
 	 * Check if we are actually a member of this group.
 	 */
 	imo = inp_findmoptions(inp);
-	idx = imo_match_group(imo, ifp, &gsa->sa);
-	if (idx == -1 || imo->imo_mfilters == NULL) {
+	imf = imo_match_group(imo, ifp, &gsa->sa);
+	if (imf == NULL) {
 		error = EADDRNOTAVAIL;
 		goto out_inp_locked;
 	}
-
-	KASSERT(imo->imo_mfilters != NULL,
-	    ("%s: imo_mfilters not allocated", __func__));
-	imf = &imo->imo_mfilters[idx];
-	inm = imo->imo_membership[idx];
+	inm = imf->imf_inm;
 
 	/*
 	 * Attempting to use the delta-based API on an
@@ -1562,7 +1512,7 @@ inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 	 *  Asked to unblock, but nothing to unblock.
 	 * If adding a new block entry, allocate it.
 	 */
-	ims = imo_match_source(imo, idx, &ssa->sa);
+	ims = imo_match_source(imf, &ssa->sa);
 	if ((ims != NULL && doblock) || (ims == NULL && !doblock)) {
 		CTR3(KTR_IGMPV3, "%s: source 0x%08x %spresent", __func__,
 		    ntohl(ssa->sin.sin_addr.s_addr), doblock ? "" : "not ");
@@ -1593,14 +1543,13 @@ inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 	/*
 	 * Begin state merge transaction at IGMP layer.
 	 */
-	IN_MULTI_LOCK();
 	CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
 	IN_MULTI_LIST_LOCK();
 	error = inm_merge(inm, imf);
 	if (error) {
 		CTR1(KTR_IGMPV3, "%s: failed to merge inm state", __func__);
 		IN_MULTI_LIST_UNLOCK();
-		goto out_in_multi_locked;
+		goto out_imf_rollback;
 	}
 
 	CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
@@ -1609,9 +1558,6 @@ inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 	if (error)
 		CTR1(KTR_IGMPV3, "%s: failed igmp downcall", __func__);
 
-out_in_multi_locked:
-
-	IN_MULTI_UNLOCK();
 out_imf_rollback:
 	if (error)
 		imf_rollback(imf);
@@ -1622,6 +1568,7 @@ out_imf_rollback:
 
 out_inp_locked:
 	INP_WUNLOCK(inp);
+	IN_MULTI_UNLOCK();
 	return (error);
 }
 
@@ -1636,9 +1583,6 @@ static struct ip_moptions *
 inp_findmoptions(struct inpcb *inp)
 {
 	struct ip_moptions	 *imo;
-	struct in_multi		**immp;
-	struct in_mfilter	 *imfp;
-	size_t			  idx;
 
 	INP_WLOCK(inp);
 	if (inp->inp_moptions != NULL)
@@ -1647,29 +1591,16 @@ inp_findmoptions(struct inpcb *inp)
 	INP_WUNLOCK(inp);
 
 	imo = malloc(sizeof(*imo), M_IPMOPTS, M_WAITOK);
-	immp = malloc(sizeof(*immp) * IP_MIN_MEMBERSHIPS, M_IPMOPTS,
-	    M_WAITOK | M_ZERO);
-	imfp = malloc(sizeof(struct in_mfilter) * IP_MIN_MEMBERSHIPS,
-	    M_INMFILTER, M_WAITOK);
 
 	imo->imo_multicast_ifp = NULL;
 	imo->imo_multicast_addr.s_addr = INADDR_ANY;
 	imo->imo_multicast_vif = -1;
 	imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
 	imo->imo_multicast_loop = in_mcast_loop;
-	imo->imo_num_memberships = 0;
-	imo->imo_max_memberships = IP_MIN_MEMBERSHIPS;
-	imo->imo_membership = immp;
-
-	/* Initialize per-group source filters. */
-	for (idx = 0; idx < IP_MIN_MEMBERSHIPS; idx++)
-		imf_init(&imfp[idx], MCAST_UNDEFINED, MCAST_EXCLUDE);
-	imo->imo_mfilters = imfp;
+	STAILQ_INIT(&imo->imo_head);
 
 	INP_WLOCK(inp);
 	if (inp->inp_moptions != NULL) {
-		free(imfp, M_INMFILTER);
-		free(immp, M_IPMOPTS);
 		free(imo, M_IPMOPTS);
 		return (inp->inp_moptions);
 	}
@@ -1680,32 +1611,25 @@ inp_findmoptions(struct inpcb *inp)
 static void
 inp_gcmoptions(struct ip_moptions *imo)
 {
-	struct in_mfilter	*imf;
+	struct in_mfilter *imf;
 	struct in_multi *inm;
 	struct ifnet *ifp;
-	size_t			 idx, nmships;
-
-	nmships = imo->imo_num_memberships;
-	for (idx = 0; idx < nmships; ++idx) {
-		imf = imo->imo_mfilters ? &imo->imo_mfilters[idx] : NULL;
-		if (imf)
-			imf_leave(imf);
-		inm = imo->imo_membership[idx];
-		ifp = inm->inm_ifp;
-		if (ifp != NULL) {
-			CURVNET_SET(ifp->if_vnet);
-			(void)in_leavegroup(inm, imf);
-			CURVNET_RESTORE();
-		} else {
-			(void)in_leavegroup(inm, imf);
+
+	while ((imf = ip_mfilter_first(&imo->imo_head)) != NULL) {
+		ip_mfilter_remove(&imo->imo_head, imf);
+
+		imf_leave(imf);
+		if ((inm = imf->imf_inm) != NULL) {
+			if ((ifp = inm->inm_ifp) != NULL) {
+				CURVNET_SET(ifp->if_vnet);
+				(void)in_leavegroup(inm, imf);
+				CURVNET_RESTORE();
+			} else {
+				(void)in_leavegroup(inm, imf);
+			}
 		}
-		if (imf)
-			imf_purge(imf);
+		ip_mfilter_free(imf);
 	}
-
-	if (imo->imo_mfilters)
-		free(imo->imo_mfilters, M_INMFILTER);
-	free(imo->imo_membership, M_IPMOPTS);
 	free(imo, M_IPMOPTS);
 }
 
@@ -1741,7 +1665,7 @@ inp_get_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	struct sockaddr_storage	*ptss;
 	struct sockaddr_storage	*tss;
 	int			 error;
-	size_t			 idx, nsrcs, ncsrcs;
+	size_t			 nsrcs, ncsrcs;
 
 	INP_WLOCK_ASSERT(inp);
 
@@ -1768,12 +1692,11 @@ inp_get_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	 * Lookup group on the socket.
 	 */
 	gsa = (sockunion_t *)&msfr.msfr_group;
-	idx = imo_match_group(imo, ifp, &gsa->sa);
-	if (idx == -1 || imo->imo_mfilters == NULL) {
+	imf = imo_match_group(imo, ifp, &gsa->sa);
+	if (imf == NULL) {
 		INP_WUNLOCK(inp);
 		return (EADDRNOTAVAIL);
 	}
-	imf = &imo->imo_mfilters[idx];
 
 	/*
 	 * Ignore memberships which are in limbo.
@@ -2033,14 +1956,11 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 	struct ip_moptions		*imo;
 	struct in_multi			*inm;
 	struct in_msource		*lims;
-	size_t				 idx;
 	int				 error, is_new;
 
 	ifp = NULL;
-	imf = NULL;
 	lims = NULL;
 	error = 0;
-	is_new = 0;
 
 	memset(&gsr, 0, sizeof(struct group_source_req));
 	gsa = (sockunion_t *)&gsr.gsr_group;
@@ -2148,13 +2068,25 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0)
 		return (EADDRNOTAVAIL);
 
+	IN_MULTI_LOCK();
+
+	/*
+	 * Find the membership in the membership list.
+	 */
 	imo = inp_findmoptions(inp);
-	idx = imo_match_group(imo, ifp, &gsa->sa);
-	if (idx == -1) {
+	imf = imo_match_group(imo, ifp, &gsa->sa);
+	if (imf == NULL) {
 		is_new = 1;
+		inm = NULL;
+
+		if (ip_mfilter_count(&imo->imo_head) >= IP_MAX_MEMBERSHIPS) {
+			error = ENOMEM;
+			goto out_inp_locked;
+		}
 	} else {
-		inm = imo->imo_membership[idx];
-		imf = &imo->imo_mfilters[idx];
+		is_new = 0;
+		inm = imf->imf_inm;
+
 		if (ssa->ss.ss_family != AF_UNSPEC) {
 			/*
 			 * MCAST_JOIN_SOURCE_GROUP on an exclusive membership
@@ -2181,7 +2113,7 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 			 * full-state SSM API with the delta-based API,
 			 * which is discouraged in the relevant RFCs.
 			 */
-			lims = imo_match_source(imo, idx, &ssa->sa);
+			lims = imo_match_source(imf, &ssa->sa);
 			if (lims != NULL /*&&
 			    lims->imsl_st[1] == MCAST_INCLUDE*/) {
 				error = EADDRNOTAVAIL;
@@ -2214,27 +2146,6 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 	 */
 	INP_WLOCK_ASSERT(inp);
 
-	if (is_new) {
-		if (imo->imo_num_memberships == imo->imo_max_memberships) {
-			error = imo_grow(imo);
-			if (error)
-				goto out_inp_locked;
-		}
-		/*
-		 * Allocate the new slot upfront so we can deal with
-		 * grafting the new source filter in same code path
-		 * as for join-source on existing membership.
-		 */
-		idx = imo->imo_num_memberships;
-		imo->imo_membership[idx] = NULL;
-		imo->imo_num_memberships++;
-		KASSERT(imo->imo_mfilters != NULL,
-		    ("%s: imf_mfilters vector was not allocated", __func__));
-		imf = &imo->imo_mfilters[idx];
-		KASSERT(RB_EMPTY(&imf->imf_sources),
-		    ("%s: imf_sources not empty", __func__));
-	}
-
 	/*
 	 * Graft new source into filter list for this inpcb's
 	 * membership of the group. The in_multi may not have
@@ -2250,7 +2161,11 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 		/* Membership starts in IN mode */
 		if (is_new) {
 			CTR1(KTR_IGMPV3, "%s: new join w/source", __func__);
-			imf_init(imf, MCAST_UNDEFINED, MCAST_INCLUDE);
+			imf = ip_mfilter_alloc(M_NOWAIT, MCAST_UNDEFINED, MCAST_INCLUDE);
+			if (imf == NULL) {
+				error = ENOMEM;
+				goto out_inp_locked;
+			}
 		} else {
 			CTR2(KTR_IGMPV3, "%s: %s source", __func__, "allow");
 		}
@@ -2259,34 +2174,41 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 			CTR1(KTR_IGMPV3, "%s: merge imf state failed",
 			    __func__);
 			error = ENOMEM;
-			goto out_imo_free;
+			goto out_inp_locked;
 		}
 	} else {
 		/* No address specified; Membership starts in EX mode */
 		if (is_new) {
 			CTR1(KTR_IGMPV3, "%s: new join w/o source", __func__);
-			imf_init(imf, MCAST_UNDEFINED, MCAST_EXCLUDE);
+			imf = ip_mfilter_alloc(M_NOWAIT, MCAST_UNDEFINED, MCAST_EXCLUDE);
+			if (imf == NULL) {
+				error = ENOMEM;
+				goto out_inp_locked;
+			}
 		}
 	}
 
 	/*
 	 * Begin state merge transaction at IGMP layer.
 	 */
-	in_pcbref(inp);
-	INP_WUNLOCK(inp);
-	IN_MULTI_LOCK();
-
 	if (is_new) {
+		in_pcbref(inp);
+		INP_WUNLOCK(inp);
+
 		error = in_joingroup_locked(ifp, &gsa->sin.sin_addr, imf,
-		    &inm);
+		    &imf->imf_inm);
+
+		INP_WLOCK(inp);
+		if (in_pcbrele_wlocked(inp)) {
+			error = ENXIO;
+			goto out_inp_unlocked;
+		}
 		if (error) {
                         CTR1(KTR_IGMPV3, "%s: in_joingroup_locked failed", 
                             __func__);
-                        IN_MULTI_LIST_UNLOCK();
-			goto out_imo_free;
+			goto out_inp_locked;
 		}
-		inm_acquire(inm);
-		imo->imo_membership[idx] = inm;
+		inm_acquire(imf->imf_inm);
 	} else {
 		CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
 		IN_MULTI_LIST_LOCK();
@@ -2295,7 +2217,9 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 			CTR1(KTR_IGMPV3, "%s: failed to merge inm state",
 				 __func__);
 			IN_MULTI_LIST_UNLOCK();
-			goto out_in_multi_locked;
+			imf_rollback(imf);
+			imf_reap(imf);
+			goto out_inp_locked;
 		}
 		CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
 		error = igmp_change_state(inm);
@@ -2303,40 +2227,30 @@ inp_join_group(struct inpcb *inp, struct sockopt *sopt)
 		if (error) {
 			CTR1(KTR_IGMPV3, "%s: failed igmp downcall",
 			    __func__);
-			goto out_in_multi_locked;
+			imf_rollback(imf);
+			imf_reap(imf);
+			goto out_inp_locked;
 		}
 	}
+	if (is_new)
+		ip_mfilter_insert(&imo->imo_head, imf);
 
-out_in_multi_locked:
+	imf_commit(imf);
+	imf = NULL;
 
+out_inp_locked:
+	INP_WUNLOCK(inp);
+out_inp_unlocked:
 	IN_MULTI_UNLOCK();
-	INP_WLOCK(inp);
-	if (in_pcbrele_wlocked(inp))
-		return (ENXIO);
-	if (error) {
-		imf_rollback(imf);
-		if (is_new)
-			imf_purge(imf);
-		else
-			imf_reap(imf);
-	} else {
-		imf_commit(imf);
-	}
 
-out_imo_free:
-	if (error && is_new) {
-		inm = imo->imo_membership[idx];
-		if (inm != NULL) {
+	if (is_new && imf) {
+		if (imf->imf_inm != NULL) {
 			IN_MULTI_LIST_LOCK();
-			inm_release_deferred(inm);
+			inm_release_deferred(imf->imf_inm);
 			IN_MULTI_LIST_UNLOCK();
 		}
-		imo->imo_membership[idx] = NULL;
-		--imo->imo_num_memberships;
+		ip_mfilter_free(imf);
 	}
-
-out_inp_locked:
-	INP_WUNLOCK(inp);
 	return (error);
 }
 
@@ -2355,12 +2269,12 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 	struct ip_moptions		*imo;
 	struct in_msource		*ims;
 	struct in_multi			*inm;
-	size_t				 idx;
-	int				 error, is_final;
+	int				 error;
+	bool				 is_final;
 
 	ifp = NULL;
 	error = 0;
-	is_final = 1;
+	is_final = true;
 
 	memset(&gsr, 0, sizeof(struct group_source_req));
 	gsa = (sockunion_t *)&gsr.gsr_group;
@@ -2460,20 +2374,21 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 	if (!IN_MULTICAST(ntohl(gsa->sin.sin_addr.s_addr)))
 		return (EINVAL);
 
+	IN_MULTI_LOCK();
+
 	/*
-	 * Find the membership in the membership array.
+	 * Find the membership in the membership list.
 	 */
 	imo = inp_findmoptions(inp);
-	idx = imo_match_group(imo, ifp, &gsa->sa);
-	if (idx == -1) {
+	imf = imo_match_group(imo, ifp, &gsa->sa);
+	if (imf == NULL) {
 		error = EADDRNOTAVAIL;
 		goto out_inp_locked;
 	}
-	inm = imo->imo_membership[idx];
-	imf = &imo->imo_mfilters[idx];
+	inm = imf->imf_inm;
 
 	if (ssa->ss.ss_family != AF_UNSPEC)
-		is_final = 0;
+		is_final = false;
 
 	/*
 	 * Begin state merge transaction at socket layer.
@@ -2485,13 +2400,14 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 	 * MCAST_LEAVE_SOURCE_GROUP is only valid for inclusive memberships.
 	 */
 	if (is_final) {
+		ip_mfilter_remove(&imo->imo_head, imf);
 		imf_leave(imf);
 	} else {
 		if (imf->imf_st[0] == MCAST_EXCLUDE) {
 			error = EADDRNOTAVAIL;
 			goto out_inp_locked;
 		}
-		ims = imo_match_source(imo, idx, &ssa->sa);
+		ims = imo_match_source(imf, &ssa->sa);
 		if (ims == NULL) {
 			CTR3(KTR_IGMPV3, "%s: source 0x%08x %spresent",
 			    __func__, ntohl(ssa->sin.sin_addr.s_addr), "not ");
@@ -2510,17 +2426,7 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 	/*
 	 * Begin state merge transaction at IGMP layer.
 	 */
-	in_pcbref(inp);
-	INP_WUNLOCK(inp);
-	IN_MULTI_LOCK();
-
-	if (is_final) {
-		/*
-		 * Give up the multicast address record to which
-		 * the membership points.
-		 */
-		(void)in_leavegroup_locked(inm, imf);
-	} else {
+	if (!is_final) {
 		CTR1(KTR_IGMPV3, "%s: merge inm state", __func__);
 		IN_MULTI_LIST_LOCK();
 		error = inm_merge(inm, imf);
@@ -2528,7 +2434,9 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 			CTR1(KTR_IGMPV3, "%s: failed to merge inm state",
 			    __func__);
 			IN_MULTI_LIST_UNLOCK();
-			goto out_in_multi_locked;
+			imf_rollback(imf);
+			imf_reap(imf);
+			goto out_inp_locked;
 		}
 
 		CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
@@ -2537,38 +2445,27 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
 		if (error) {
 			CTR1(KTR_IGMPV3, "%s: failed igmp downcall",
 			    __func__);
+			imf_rollback(imf);
+			imf_reap(imf);
+			goto out_inp_locked;
 		}
 	}
-
-out_in_multi_locked:
-
-	IN_MULTI_UNLOCK();
-	INP_WLOCK(inp);
-	if (in_pcbrele_wlocked(inp))
-		return (ENXIO);
-
-	if (error)
-		imf_rollback(imf);
-	else
-		imf_commit(imf);
-
+	imf_commit(imf);
 	imf_reap(imf);
 
-	if (is_final) {
-		/* Remove the gap in the membership and filter array. */
-		KASSERT(RB_EMPTY(&imf->imf_sources),
-		    ("%s: imf_sources not empty", __func__));
-		for (++idx; idx < imo->imo_num_memberships; ++idx) {
-			imo->imo_membership[idx - 1] = imo->imo_membership[idx];
-			imo->imo_mfilters[idx - 1] = imo->imo_mfilters[idx];
-		}
-		imf_init(&imo->imo_mfilters[idx - 1], MCAST_UNDEFINED,
-		    MCAST_EXCLUDE);
-		imo->imo_num_memberships--;
-	}
-
 out_inp_locked:
 	INP_WUNLOCK(inp);
+
+	if (is_final && imf) {
+		/*
+		 * Give up the multicast address record to which
+		 * the membership points.
+		 */
+		(void) in_leavegroup_locked(imf->imf_inm, imf);
+		ip_mfilter_free(imf);
+	}
+
+	IN_MULTI_UNLOCK();
 	return (error);
 }
 
@@ -2658,7 +2555,6 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	struct in_mfilter	*imf;
 	struct ip_moptions	*imo;
 	struct in_multi		*inm;
-	size_t			 idx;
 	int			 error;
 
 	error = sooptcopyin(sopt, &msfr, sizeof(struct __msfilterreq),
@@ -2690,18 +2586,19 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	if (ifp == NULL)
 		return (EADDRNOTAVAIL);
 
+	IN_MULTI_LOCK();
+
 	/*
 	 * Take the INP write lock.
 	 * Check if this socket is a member of this group.
 	 */
 	imo = inp_findmoptions(inp);
-	idx = imo_match_group(imo, ifp, &gsa->sa);
-	if (idx == -1 || imo->imo_mfilters == NULL) {
+	imf = imo_match_group(imo, ifp, &gsa->sa);
+	if (imf == NULL) {
 		error = EADDRNOTAVAIL;
 		goto out_inp_locked;
 	}
-	inm = imo->imo_membership[idx];
-	imf = &imo->imo_mfilters[idx];
+	inm = imf->imf_inm;
 
 	/*
 	 * Begin state merge transaction at socket layer.
@@ -2778,7 +2675,6 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
 		goto out_imf_rollback;
 
 	INP_WLOCK_ASSERT(inp);
-	IN_MULTI_LOCK();
 
 	/*
 	 * Begin state merge transaction at IGMP layer.
@@ -2789,7 +2685,7 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	if (error) {
 		CTR1(KTR_IGMPV3, "%s: failed to merge inm state", __func__);
 		IN_MULTI_LIST_UNLOCK();
-		goto out_in_multi_locked;
+		goto out_imf_rollback;
 	}
 
 	CTR1(KTR_IGMPV3, "%s: doing igmp downcall", __func__);
@@ -2798,10 +2694,6 @@ inp_set_source_filters(struct inpcb *inp, struct sockopt *sopt)
 	if (error)
 		CTR1(KTR_IGMPV3, "%s: failed igmp downcall", __func__);
 
-out_in_multi_locked:
-
-	IN_MULTI_UNLOCK();
-
 out_imf_rollback:
 	if (error)
 		imf_rollback(imf);
@@ -2812,6 +2704,7 @@ out_imf_rollback:
 
 out_inp_locked:
 	INP_WUNLOCK(inp);
+	IN_MULTI_UNLOCK();
 	return (error);
 }