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Date:      Sat, 12 Sep 2009 19:50:04 GMT
From:      dfilter@FreeBSD.ORG (dfilter service)
To:        freebsd-net@FreeBSD.org
Subject:   Re: kern/138690: commit references a PR
Message-ID:  <200909121950.n8CJo4bA080455@freefall.freebsd.org>
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The following reply was made to PR kern/138690; it has been noted by GNATS.

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: kern/138690: commit references a PR
Date: Sat, 12 Sep 2009 19:46:12 +0000 (UTC)

 Author: bms
 Date: Sat Sep 12 19:45:55 2009
 New Revision: 197132
 URL: http://svn.freebsd.org/changeset/base/197132
 
 Log:
   Tighten input checking in inp_join_group():
    * Don't try to use the source address, when its family is unspecified.
    * If we get a join without a source, on an existing inclusive
      mode group, this is an error, as it would change the filter mode.
   
   Fix a problem with the handling of in_mfilter for new memberships:
    * Do not rely on imf being NULL; it is explicitly initialized to a
      non-NULL pointer when constructing a membership.
    * Explicitly initialize *imf to EX mode when the source address
      is unspecified.
   
   This fixes a problem with in_mfilter slot recycling in the join path.
   
   PR:		138690
   Submitted by:	Stef Walter
   MFC after:	5 days
 
 Modified:
   head/sys/netinet/in_mcast.c
 
 Modified: head/sys/netinet/in_mcast.c
 ==============================================================================
 --- head/sys/netinet/in_mcast.c	Sat Sep 12 19:27:54 2009	(r197131)
 +++ head/sys/netinet/in_mcast.c	Sat Sep 12 19:45:55 2009	(r197132)
 @@ -1957,11 +1957,6 @@ inp_join_group(struct inpcb *inp, struct
  	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0)
  		return (EADDRNOTAVAIL);
  
 -	/*
 -	 * MCAST_JOIN_SOURCE on an exclusive membership is an error.
 -	 * On an existing inclusive membership, it just adds the
 -	 * source to the filter list.
 -	 */
  	imo = inp_findmoptions(inp);
  	idx = imo_match_group(imo, ifp, &gsa->sa);
  	if (idx == -1) {
 @@ -1969,15 +1964,33 @@ inp_join_group(struct inpcb *inp, struct
  	} else {
  		inm = imo->imo_membership[idx];
  		imf = &imo->imo_mfilters[idx];
 -		if (ssa->ss.ss_family != AF_UNSPEC &&
 -		    imf->imf_st[1] != MCAST_INCLUDE) {
 -			error = EINVAL;
 -			goto out_inp_locked;
 -		}
 -		lims = imo_match_source(imo, idx, &ssa->sa);
 -		if (lims != NULL) {
 -			error = EADDRNOTAVAIL;
 -			goto out_inp_locked;
 +		if (ssa->ss.ss_family != AF_UNSPEC) {
 +			/*
 +			 * MCAST_JOIN_SOURCE on an exclusive membership
 +			 * is an error. On an existing inclusive membership,
 +			 * it just adds the source to the filter list.
 +			 */
 +			if (imf->imf_st[1] != MCAST_INCLUDE) {
 +				error = EINVAL;
 +				goto out_inp_locked;
 +			}
 +			/* Throw out duplicates. */
 +			lims = imo_match_source(imo, idx, &ssa->sa);
 +			if (lims != NULL) {
 +				error = EADDRNOTAVAIL;
 +				goto out_inp_locked;
 +			}
 +		} else {
 +			/*
 +			 * MCAST_JOIN_GROUP on an existing inclusive
 +			 * membership is an error; if you want to change
 +			 * filter mode, you must use the userland API
 +			 * setsourcefilter().
 +			 */
 +			if (imf->imf_st[1] == MCAST_INCLUDE) {
 +				error = EINVAL;
 +				goto out_inp_locked;
 +			}
  		}
  	}
  
 @@ -2010,7 +2023,8 @@ inp_join_group(struct inpcb *inp, struct
  	/*
  	 * Graft new source into filter list for this inpcb's
  	 * membership of the group. The in_multi may not have
 -	 * been allocated yet if this is a new membership.
 +	 * been allocated yet if this is a new membership, however,
 +	 * the in_mfilter slot will be allocated and must be initialized.
  	 */
  	if (ssa->ss.ss_family != AF_UNSPEC) {
  		/* Membership starts in IN mode */
 @@ -2027,6 +2041,12 @@ inp_join_group(struct inpcb *inp, struct
  			error = ENOMEM;
  			goto out_imo_free;
  		}
 +	} 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);
 +		}
  	}
  
  	/*
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