Changeset 92093 in vbox for trunk

Timestamp:

Oct 27, 2021 8:18:16 AM (3 years ago)

Author:

vboxsync

Message:

Devices/Network/NAT: Add option to disallow traffic from the guest to reach the host's loopback interface, bugref:9896

Location:

trunk/src/VBox/Devices/Network

Files:

• DrvNAT.cpp (modified) (3 diffs)
• slirp/ip_icmp.c (modified) (1 diff)
• slirp/libslirp.h (modified) (1 diff)
• slirp/slirp.c (modified) (3 diffs)
• slirp/slirp_state.h (modified) (1 diff)
• slirp/tcp_input.c (modified) (1 diff)
• slirp/udp.c (modified) (1 diff)

trunk/src/VBox/Devices/Network/DrvNAT.cpp

@@ -1599 +1599 @@
                                   "|ICMPCacheLimit"
                                   "|SoMaxConnection"
+                                  "|LocalhostReachable"
 //#ifdef VBOX_WITH_DNSMAPPING_IN_HOSTRESOLVER
                                   "|HostResolverMappings"
@@ -1626 +1627 @@
     int iIcmpCacheLimit = 100;
     GET_S32(rc, pDrvIns, pCfg, "ICMPCacheLimit", iIcmpCacheLimit);
+    bool fLocalhostReachable = false;
+    GET_BOOL(rc, pDrvIns, pCfg, "LocalhostReachable", fLocalhostReachable);
 
     i32AliasMode |= (i32MainAliasMode & 0x1 ? 0x1 : 0);
@@ -1666 +1669 @@
     rc = slirp_init(&pThis->pNATState, RT_H2N_U32(Network.u), Netmask.u,
                     fPassDomain, !!fUseHostResolver, i32AliasMode,
-                    iIcmpCacheLimit, pThis);
+                    iIcmpCacheLimit, fLocalhostReachable, pThis);
     if (RT_SUCCESS(rc))
     {

trunk/src/VBox/Devices/Network/slirp/ip_icmp.c

@@ -481 +481 @@
                 || CTL_CHECK(dst, CTL_TFTP))
             {
+                /* Don't reply to ping requests for the hosts loopback interface if it is disabled. */
+                if (   CTL_CHECK(dst, CTL_ALIAS)
+                    && !pData->fLocalhostReachable)
+                    goto done;
+
                 uint8_t echo_reply = ICMP_ECHOREPLY;
                 m_copyback(pData, m, hlen + RT_OFFSETOF(struct icmp, icmp_type),

trunk/src/VBox/Devices/Network/slirp/libslirp.h

@@ -47 +47 @@
 #endif
 
-int slirp_init(PNATState *, uint32_t, uint32_t, bool, bool, int, int, void *);
+int slirp_init(PNATState *, uint32_t, uint32_t, bool, bool, int, int, bool, void *);
 void slirp_register_statistics(PNATState pData, PPDMDRVINS pDrvIns);
 void slirp_deregister_statistics(PNATState pData, PPDMDRVINS pDrvIns);

trunk/src/VBox/Devices/Network/slirp/slirp.c

@@ -299 +299 @@
 int slirp_init(PNATState *ppData, uint32_t u32NetAddr, uint32_t u32Netmask,
                bool fPassDomain, bool fUseHostResolver, int i32AliasMode,
-               int iIcmpCacheLimit, void *pvUser)
+               int iIcmpCacheLimit, bool fLocalhostReachable, void *pvUser)
 {
     int rc;
@@ -316 +316 @@
     pData->fUseHostResolver = fUseHostResolver;
     pData->fUseHostResolverPermanent = fUseHostResolver;
+    pData->fLocalhostReachable = fLocalhostReachable;
     pData->pvUser = pvUser;
     pData->netmask = u32Netmask;
@@ -1353 +1354 @@
                 || CTL_CHECK(ip4TargetAddress, CTL_TFTP))
             {
+#if 0 /* Dropping ARP requests destined for CTL_ALIAS breaks all outgoing traffic completely, so don't do that... */
+                /* Don't reply to ARP requests for the hosts loopback interface if it is disabled. */
+                if (   CTL_CHECK(ip4TargetAddress, CTL_ALIAS)
+                    && !pData->fLocalhostReachable)
+                    break;
+#endif
                 slirp_update_guest_addr_guess(pData, *(uint32_t *)pARPHeader->ar_sip, "arp request");
                 arp_output(pData, pEtherHeader->h_source, pARPHeader, ip4TargetAddress);

trunk/src/VBox/Devices/Network/slirp/slirp_state.h

@@ -287 +287 @@
     /* this field control behaviour of DHCP server */
     bool fUseDnsProxy;
+    /** Flag whether the guest can contact services on the host's
+     * loopback interface (127.0.0.1/localhost). */
+    bool fLocalhostReachable;
 
     LIST_HEAD(RT_NOTHING, libalias) instancehead;

trunk/src/VBox/Devices/Network/slirp/tcp_input.c

@@ -502 +502 @@
     }
     LogFlowFunc(("(leave) findso: %R[natsock]\n", so));
+
+    /*
+     * Check whether the packet is targeting CTL_ALIAS and drop it if the connection wasn't
+     * initiated by localhost (so == NULL), see @bugref{9896}.
+     */
+    if (   (RT_N2H_U32(ti->ti_dst.s_addr) & ~pData->netmask) == CTL_ALIAS
+        && !pData->fLocalhostReachable
+        && !so)
+    {
+        LogFlowFunc(("Packet for CTL_ALIAS and fLocalhostReachable=false so=NULL -> drop\n"));
+        goto drop;
+    }
 
     /*

trunk/src/VBox/Devices/Network/slirp/udp.c

@@ -233 +233 @@
 
     /*
+     * Drop UDP packets destind for CTL_ALIAS (i.e. the hosts loopback interface)
+     * if it is disabled.
+     */
+    if (   CTL_CHECK(ip->ip_dst.s_addr, CTL_ALIAS)
+        && !pData->fLocalhostReachable)
+        goto done_free_mbuf;
+
+    /*
      * Locate pcb for datagram.
      */