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Commit 5ab4a6c8 authored by David L Stevens's avatar David L Stevens Committed by David S. Miller
Browse files

[IPV6] mcast: Fix multiple issues in MLDv2 reports. 



The below "jumbo" patch fixes the following problems in MLDv2.

1) Add necessary "ntohs" to recent "pskb_may_pull" check [breaks
        all nonzero source queries on little-endian (!)]

2) Add locking to source filter list [resend of prior patch]

3) fix "mld_marksources()" to
        a) send nothing when all queried sources are excluded
        b) send full exclude report when source queried sources are
                not excluded
        c) don't schedule a timer when there's nothing to report

NOTE: RFC 3810 specifies the source list should be saved and each
  source reported individually as an IS_IN. This is an obvious DOS
  path, requiring the host to store and then multicast as many sources
  as are queried (e.g., millions...). This alternative sends a full, 
  relevant report that's limited to number of sources present on the
  machine.

4) fix "add_grec()" to send empty-source records when it should
        The original check doesn't account for a non-empty source
        list with all sources inactive; the new code keeps that
        short-circuit case, and also generates the group header
        with an empty list if needed.

5) fix mca_crcount decrement to be after add_grec(), which needs
        its original value

These issues (other than item #1 ;-) ) were all found by Yan Zheng,
much thanks!

Signed-off-by: default avatarDavid L Stevens <dlstevens@us.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1b93ae64

include/net/if_inet6.h

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ struct ipv6_mc_socklist 
	struct in6_addr		addr;

	int			ifindex;

	struct ipv6_mc_socklist *next;

	rwlock_t		sflock;

	unsigned int		sfmode;		/* MCAST_{INCLUDE,EXCLUDE} */

	struct ip6_sf_socklist	*sflist;

};

net/ipv6/mcast.c

+110 −30
Original line number Diff line number Diff line
@@ -224,6 +224,7 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, struct in6_addr *addr) 


	mc_lst->ifindex = dev->ifindex;

	mc_lst->sfmode = MCAST_EXCLUDE;

	mc_lst->sflock = RW_LOCK_UNLOCKED;

	mc_lst->sflist = NULL;



	/*
@@ -360,6 +361,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk, 
	struct ip6_sf_socklist *psl;

	int i, j, rv;

	int leavegroup = 0;

	int pmclocked = 0;

	int err;



	if (pgsr->gsr_group.ss_family != AF_INET6 ||
@@ -403,6 +405,9 @@ int ip6_mc_source(int add, int omode, struct sock *sk, 
		pmc->sfmode = omode;

	}



	write_lock_bh(&pmc->sflock);

	pmclocked = 1;



	psl = pmc->sflist;

	if (!add) {

		if (!psl)
@@ -475,6 +480,8 @@ int ip6_mc_source(int add, int omode, struct sock *sk, 
	/* update the interface list */

	ip6_mc_add_src(idev, group, omode, 1, source, 1);

done:

	if (pmclocked)

		write_unlock_bh(&pmc->sflock);

	read_unlock_bh(&ipv6_sk_mc_lock);

	read_unlock_bh(&idev->lock);

	in6_dev_put(idev);
@@ -510,6 +517,8 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) 
	dev = idev->dev;



	err = 0;

	read_lock_bh(&ipv6_sk_mc_lock);



	if (gsf->gf_fmode == MCAST_INCLUDE && gsf->gf_numsrc == 0) {

		leavegroup = 1;

		goto done;
@@ -549,6 +558,8 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) 
		newpsl = NULL;

		(void) ip6_mc_add_src(idev, group, gsf->gf_fmode, 0, NULL, 0);

	}



	write_lock_bh(&pmc->sflock);

	psl = pmc->sflist;

	if (psl) {

		(void) ip6_mc_del_src(idev, group, pmc->sfmode,
@@ -558,8 +569,10 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) 
		(void) ip6_mc_del_src(idev, group, pmc->sfmode, 0, NULL, 0);

	pmc->sflist = newpsl;

	pmc->sfmode = gsf->gf_fmode;

	write_unlock_bh(&pmc->sflock);

	err = 0;

done:

	read_unlock_bh(&ipv6_sk_mc_lock);

	read_unlock_bh(&idev->lock);

	in6_dev_put(idev);

	dev_put(dev);
@@ -592,6 +605,11 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, 
	dev = idev->dev;



	err = -EADDRNOTAVAIL;

	/*

	 * changes to the ipv6_mc_list require the socket lock and

	 * a read lock on ip6_sk_mc_lock. We have the socket lock,

	 * so reading the list is safe.

	 */



	for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) {

		if (pmc->ifindex != gsf->gf_interface)
@@ -614,6 +632,10 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, 
	    copy_to_user(optval, gsf, GROUP_FILTER_SIZE(0))) {

		return -EFAULT;

	}

	/* changes to psl require the socket lock, a read lock on

	 * on ipv6_sk_mc_lock and a write lock on pmc->sflock. We

	 * have the socket lock, so reading here is safe.

	 */

	for (i=0; i<copycount; i++) {

		struct sockaddr_in6 *psin6;

		struct sockaddr_storage ss;
@@ -650,6 +672,7 @@ int inet6_mc_check(struct sock *sk, struct in6_addr *mc_addr, 
		read_unlock(&ipv6_sk_mc_lock);

		return 1;

	}

	read_lock(&mc->sflock);

	psl = mc->sflist;

	if (!psl) {

		rv = mc->sfmode == MCAST_EXCLUDE;
@@ -665,6 +688,7 @@ int inet6_mc_check(struct sock *sk, struct in6_addr *mc_addr, 
		if (mc->sfmode == MCAST_EXCLUDE && i < psl->sl_count)

			rv = 0;

	}

	read_unlock(&mc->sflock);

	read_unlock(&ipv6_sk_mc_lock);



	return rv;
@@ -1068,17 +1092,51 @@ static void igmp6_group_queried(struct ifmcaddr6 *ma, unsigned long resptime) 
	ma->mca_flags |= MAF_TIMER_RUNNING;

}



static void mld_marksources(struct ifmcaddr6 *pmc, int nsrcs,

/* mark EXCLUDE-mode sources */

static int mld_xmarksources(struct ifmcaddr6 *pmc, int nsrcs,

	struct in6_addr *srcs)

{

	struct ip6_sf_list *psf;

	int i, scount;



	scount = 0;

	for (psf=pmc->mca_sources; psf; psf=psf->sf_next) {

		if (scount == nsrcs)

			break;

		for (i=0; i<nsrcs; i++) {

			/* skip inactive filters */

			if (pmc->mca_sfcount[MCAST_INCLUDE] ||

			    pmc->mca_sfcount[MCAST_EXCLUDE] !=

			    psf->sf_count[MCAST_EXCLUDE])

				continue;

			if (ipv6_addr_equal(&srcs[i], &psf->sf_addr)) {

				scount++;

				break;

			}

		}

	}

	pmc->mca_flags &= ~MAF_GSQUERY;

	if (scount == nsrcs)	/* all sources excluded */

		return 0;

	return 1;

}



static int mld_marksources(struct ifmcaddr6 *pmc, int nsrcs,

	struct in6_addr *srcs)

{

	struct ip6_sf_list *psf;

	int i, scount;



	if (pmc->mca_sfmode == MCAST_EXCLUDE)

		return mld_xmarksources(pmc, nsrcs, srcs);



	/* mark INCLUDE-mode sources */



	scount = 0;

	for (psf=pmc->mca_sources; psf; psf=psf->sf_next) {

		if (scount == nsrcs)

			break;

		for (i=0; i<nsrcs; i++)

		for (i=0; i<nsrcs; i++) {

			if (ipv6_addr_equal(&srcs[i], &psf->sf_addr)) {

				psf->sf_gsresp = 1;

				scount++;
@@ -1086,6 +1144,13 @@ static void mld_marksources(struct ifmcaddr6 *pmc, int nsrcs, 
			}

		}

	}

	if (!scount) {

		pmc->mca_flags &= ~MAF_GSQUERY;

		return 0;

	}

	pmc->mca_flags |= MAF_GSQUERY;

	return 1;

}



int igmp6_event_query(struct sk_buff *skb)

{
@@ -1167,7 +1232,7 @@ int igmp6_event_query(struct sk_buff *skb) 
		/* mark sources to include, if group & source-specific */

		if (mlh2->nsrcs != 0) {

			if (!pskb_may_pull(skb, srcs_offset + 

				mlh2->nsrcs * sizeof(struct in6_addr))) {

			    ntohs(mlh2->nsrcs) * sizeof(struct in6_addr))) {

				in6_dev_put(idev);

				return -EINVAL;

			}
@@ -1203,9 +1268,8 @@ int igmp6_event_query(struct sk_buff *skb) 
				else

					ma->mca_flags &= ~MAF_GSQUERY;

			}

			if (ma->mca_flags & MAF_GSQUERY)

				mld_marksources(ma, ntohs(mlh2->nsrcs),

					mlh2->srcs);

			if (!(ma->mca_flags & MAF_GSQUERY) ||

			   mld_marksources(ma, ntohs(mlh2->nsrcs), mlh2->srcs))

				igmp6_group_queried(ma, max_delay);

			spin_unlock_bh(&ma->mca_lock);

			if (group_type != IPV6_ADDR_ANY)
@@ -1281,7 +1345,18 @@ static int is_in(struct ifmcaddr6 *pmc, struct ip6_sf_list *psf, int type, 
	case MLD2_MODE_IS_EXCLUDE:

		if (gdeleted || sdeleted)

			return 0;

		return !((pmc->mca_flags & MAF_GSQUERY) && !psf->sf_gsresp);

		if (!((pmc->mca_flags & MAF_GSQUERY) && !psf->sf_gsresp)) {

			if (pmc->mca_sfmode == MCAST_INCLUDE)

				return 1;

			/* don't include if this source is excluded

			 * in all filters

			 */

			if (psf->sf_count[MCAST_INCLUDE])

				return 0;

			return pmc->mca_sfcount[MCAST_EXCLUDE] ==

				psf->sf_count[MCAST_EXCLUDE];

		}

		return 0;

	case MLD2_CHANGE_TO_INCLUDE:

		if (gdeleted || sdeleted)

			return 0;
@@ -1450,7 +1525,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, 
	struct mld2_report *pmr;

	struct mld2_grec *pgr = NULL;

	struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list;

	int scount, first, isquery, truncate;

	int scount, stotal, first, isquery, truncate;



	if (pmc->mca_flags & MAF_NOREPORT)

		return skb;
@@ -1460,25 +1535,13 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, 
	truncate = type == MLD2_MODE_IS_EXCLUDE ||

		    type == MLD2_CHANGE_TO_EXCLUDE;



	stotal = scount = 0;



	psf_list = sdeleted ? &pmc->mca_tomb : &pmc->mca_sources;



	if (!*psf_list) {

		if (type == MLD2_ALLOW_NEW_SOURCES ||

		    type == MLD2_BLOCK_OLD_SOURCES)

			return skb;

		if (pmc->mca_crcount || isquery) {

			/* make sure we have room for group header and at

			 * least one source.

			 */

			if (skb && AVAILABLE(skb) < sizeof(struct mld2_grec)+

			    sizeof(struct in6_addr)) {

				mld_sendpack(skb);

				skb = NULL; /* add_grhead will get a new one */

			}

			skb = add_grhead(skb, pmc, type, &pgr);

		}

		return skb;

	}

	if (!*psf_list)

		goto empty_source;



	pmr = skb ? (struct mld2_report *)skb->h.raw : NULL;



	/* EX and TO_EX get a fresh packet, if needed */
@@ -1491,7 +1554,6 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, 
		}

	}

	first = 1;

	scount = 0;

	psf_prev = NULL;

	for (psf=*psf_list; psf; psf=psf_next) {

		struct in6_addr *psrc;
@@ -1525,7 +1587,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, 
		}

		psrc = (struct in6_addr *)skb_put(skb, sizeof(*psrc));

		*psrc = psf->sf_addr;

		scount++;

		scount++; stotal++;

		if ((type == MLD2_ALLOW_NEW_SOURCES ||

		     type == MLD2_BLOCK_OLD_SOURCES) && psf->sf_crcount) {

			psf->sf_crcount--;
@@ -1540,6 +1602,21 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, 
		}

		psf_prev = psf;

	}



empty_source:

	if (!stotal) {

		if (type == MLD2_ALLOW_NEW_SOURCES ||

		    type == MLD2_BLOCK_OLD_SOURCES)

			return skb;

		if (pmc->mca_crcount || isquery) {

			/* make sure we have room for group header */

			if (skb && AVAILABLE(skb) < sizeof(struct mld2_grec)) {

				mld_sendpack(skb);

				skb = NULL; /* add_grhead will get a new one */

			}

			skb = add_grhead(skb, pmc, type, &pgr);

		}

	}

	if (pgr)

		pgr->grec_nsrcs = htons(scount);
@@ -1621,11 +1698,11 @@ static void mld_send_cr(struct inet6_dev *idev) 
			skb = add_grec(skb, pmc, dtype, 1, 1);

		}

		if (pmc->mca_crcount) {

			pmc->mca_crcount--;

			if (pmc->mca_sfmode == MCAST_EXCLUDE) {

				type = MLD2_CHANGE_TO_INCLUDE;

				skb = add_grec(skb, pmc, type, 1, 0);

			}

			pmc->mca_crcount--;

			if (pmc->mca_crcount == 0) {

				mld_clear_zeros(&pmc->mca_tomb);

				mld_clear_zeros(&pmc->mca_sources);
@@ -1659,12 +1736,12 @@ static void mld_send_cr(struct inet6_dev *idev) 


		/* filter mode changes */

		if (pmc->mca_crcount) {

			pmc->mca_crcount--;

			if (pmc->mca_sfmode == MCAST_EXCLUDE)

				type = MLD2_CHANGE_TO_EXCLUDE;

			else

				type = MLD2_CHANGE_TO_INCLUDE;

			skb = add_grec(skb, pmc, type, 0, 0);

			pmc->mca_crcount--;

		}

		spin_unlock_bh(&pmc->mca_lock);

	}
@@ -2023,6 +2100,9 @@ static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml, 
{

	int err;



	/* callers have the socket lock and a write lock on ipv6_sk_mc_lock,

	 * so no other readers or writers of iml or its sflist

	 */

	if (iml->sflist == 0) {

		/* any-source empty exclude case */

		return ip6_mc_del_src(idev, &iml->addr, iml->sfmode, 0, NULL, 0);