Author: eugen
Date: Sat Oct 27 04:53:25 2018
New Revision: 339807
URL: https://svnweb.freebsd.org/changeset/base/339807

Log:
  Prevent multicast code from panicing due to unprotected access to INADDR_HASH.
  
  PR:                   220078
  MFC after:            1 month
  Differential Revision:        https://reviews.freebsd.org/D12457
  Tested-by:            Cassiano Peixoto and others

Modified:
  head/sys/netinet/in_mcast.c

Modified: head/sys/netinet/in_mcast.c
==============================================================================
--- head/sys/netinet/in_mcast.c Sat Oct 27 04:45:28 2018        (r339806)
+++ head/sys/netinet/in_mcast.c Sat Oct 27 04:53:25 2018        (r339807)
@@ -1444,6 +1444,7 @@ static int
 inp_block_unblock_source(struct inpcb *inp, struct sockopt *sopt)
 {
        struct group_source_req          gsr;
+       struct rm_priotracker            in_ifa_tracker;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
@@ -1481,9 +1482,11 @@ inp_block_unblock_source(struct inpcb *inp, struct soc
                ssa->sin.sin_len = sizeof(struct sockaddr_in);
                ssa->sin.sin_addr = mreqs.imr_sourceaddr;
 
-               if (!in_nullhost(mreqs.imr_interface))
+               if (!in_nullhost(mreqs.imr_interface)) {
+                       IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(mreqs.imr_interface, ifp);
-
+                       IN_IFADDR_RUNLOCK(&in_ifa_tracker);
+               }
                if (sopt->sopt_name == IP_BLOCK_SOURCE)
                        doblock = 1;
 
@@ -1969,7 +1972,6 @@ inp_getmoptions(struct inpcb *inp, struct sockopt *sop
  *
  * Returns NULL if no ifp could be found.
  *
- * SMPng: TODO: Acquire the appropriate locks for INADDR_TO_IFP.
  * FUTURE: Implement IPv4 source-address selection.
  */
 static struct ifnet *
@@ -1987,7 +1989,9 @@ inp_lookup_mcast_ifp(const struct inpcb *inp,
 
        ifp = NULL;
        if (!in_nullhost(ina)) {
+               IN_IFADDR_RLOCK(&in_ifa_tracker);
                INADDR_TO_IFP(ina, ifp);
+               IN_IFADDR_RUNLOCK(&in_ifa_tracker);
        } else {
                fibnum = inp ? inp->inp_inc.inc_fibnum : 0;
                if (fib4_lookup_nh_basic(fibnum, gsin->sin_addr, 0, 0, &nh4)==0)
@@ -2332,6 +2336,7 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sop
 {
        struct group_source_req          gsr;
        struct ip_mreq_source            mreqs;
+       struct rm_priotracker            in_ifa_tracker;
        sockunion_t                     *gsa, *ssa;
        struct ifnet                    *ifp;
        struct in_mfilter               *imf;
@@ -2390,9 +2395,11 @@ inp_leave_group(struct inpcb *inp, struct sockopt *sop
                 * XXX NOTE WELL: The RFC 3678 API is preferred because
                 * using an IPv4 address as a key is racy.
                 */
-               if (!in_nullhost(mreqs.imr_interface))
+               if (!in_nullhost(mreqs.imr_interface)) {
+                       IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(mreqs.imr_interface, ifp);
-
+                       IN_IFADDR_RUNLOCK(&in_ifa_tracker);
+               }
                CTR3(KTR_IGMPV3, "%s: imr_interface = 0x%08x, ifp = %p",
                    __func__, ntohl(mreqs.imr_interface.s_addr), ifp);
 
@@ -2560,6 +2567,7 @@ out_inp_locked:
 static int
 inp_set_multicast_if(struct inpcb *inp, struct sockopt *sopt)
 {
+       struct rm_priotracker    in_ifa_tracker;
        struct in_addr           addr;
        struct ip_mreqn          mreqn;
        struct ifnet            *ifp;
@@ -2598,7 +2606,9 @@ inp_set_multicast_if(struct inpcb *inp, struct sockopt
                if (in_nullhost(addr)) {
                        ifp = NULL;
                } else {
+                       IN_IFADDR_RLOCK(&in_ifa_tracker);
                        INADDR_TO_IFP(addr, ifp);
+                       IN_IFADDR_RUNLOCK(&in_ifa_tracker);
                        if (ifp == NULL)
                                return (EADDRNOTAVAIL);
                }
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