Add slirp_restrict option (Gleb Natapov)

Add "slirp firewall" to permit connection only to vmchannel addresses.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6241 c046a42c-6fe2-441c-8c8c-71466251a162

7 files changed, 57 insertions, 14 deletions

diff --git a/bootp.c b/bootp.c
index 49f1019..5bf59d7 100644
--- a/bootp.c
+++ b/bootp.c
@@ -219,16 +219,18 @@ static void bootp_reply(struct bootp_t *bp)
         *q++ = 0xff;
         *q++ = 0x00;
 
-        *q++ = RFC1533_GATEWAY;
-        *q++ = 4;
-        memcpy(q, &saddr.sin_addr, 4);
-        q += 4;
-
-        *q++ = RFC1533_DNS;
-        *q++ = 4;
-        dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
-        memcpy(q, &dns_addr, 4);
-        q += 4;
+        if (!slirp_restrict) {
+            *q++ = RFC1533_GATEWAY;
+            *q++ = 4;
+            memcpy(q, &saddr.sin_addr, 4);
+            q += 4;
+
+            *q++ = RFC1533_DNS;
+            *q++ = 4;
+            dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
+            memcpy(q, &dns_addr, 4);
+            q += 4;
+        }
 
         *q++ = RFC2132_LEASE_TIME;
         *q++ = 4;
diff --git a/ip_input.c b/ip_input.c
index 38210b3..a2afc53 100644
--- a/ip_input.c
+++ b/ip_input.c
@@ -132,6 +132,27 @@ void ip_input(m) struct mbuf *m;
         STAT(ipstat.ips_tooshort++);
         goto bad;
     }
+
+    if (slirp_restrict) {
+        if (memcmp(&ip->ip_dst.s_addr, &special_addr, 3)) {
+            if (ip->ip_dst.s_addr == 0xffffffff && ip->ip_p != IPPROTO_UDP)
+                goto bad;
+        } else {
+            int host = ntohl(ip->ip_dst.s_addr) & 0xff;
+            struct ex_list *ex_ptr;
+
+            if (host == 0xff)
+                goto bad;
+
+            for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
+                if (ex_ptr->ex_addr == host)
+                    break;
+
+            if (!ex_ptr)
+                goto bad;
+        }
+    }
+
     /* Should drop packet if mbuf too long? hmmm... */
     if (m->m_len > ip->ip_len)
         m_adj(m, ip->ip_len - m->m_len);
diff --git a/libslirp.h b/libslirp.h
index 24cc8b0..3356bdd 100644
--- a/libslirp.h
+++ b/libslirp.h
@@ -5,7 +5,7 @@
 extern "C" {
 #endif
 
-void slirp_init(void);
+void slirp_init(int restrict, char *special_ip);
 
 void slirp_select_fill(int *pnfds, fd_set *readfds, fd_set *writefds,
                        fd_set *xfds);
diff --git a/main.h b/main.h
index b02c879..c534c8b 100644
--- a/main.h
+++ b/main.h
@@ -44,6 +44,8 @@ extern int towrite_max;
 extern int ppp_exit;
 extern int tcp_keepintvl;
 extern uint8_t client_ethaddr[6];
+extern char *slirp_special_ip;
+extern int slirp_restrict;
 
 #define PROTO_SLIP 0x1
 #ifdef USE_PPP
diff --git a/slirp.c b/slirp.c
index 490ab26..3104fd9 100644
--- a/slirp.c
+++ b/slirp.c
@@ -46,6 +46,8 @@ static struct in_addr client_ipaddr;
 
 static const uint8_t zero_ethaddr[6] = { 0, 0, 0, 0, 0, 0 };
 
+char *slirp_special_ip = CTL_SPECIAL;
+int slirp_restrict;
 int do_slowtimo;
 int link_up;
 struct timeval tt;
@@ -164,7 +166,7 @@ static void slirp_cleanup(void)
 }
 #endif
 
-void slirp_init(void)
+void slirp_init(int restrict, char *special_ip)
 {
     //    debug_init("/tmp/slirp.log", DEBUG_DEFAULT);
 
@@ -177,6 +179,7 @@ void slirp_init(void)
 #endif
 
     link_up = 1;
+    slirp_restrict = restrict;
 
     if_init();
     ip_init();
@@ -192,7 +195,10 @@ void slirp_init(void)
         fprintf(stderr, "Warning: No DNS servers found\n");
     }
 
-    inet_aton(CTL_SPECIAL, &special_addr);
+    if (special_ip)
+        slirp_special_ip = special_ip;
+
+    inet_aton(slirp_special_ip, &special_addr);
     alias_addr.s_addr = special_addr.s_addr | htonl(CTL_ALIAS);
     getouraddr();
 }
diff --git a/tcp_input.c b/tcp_input.c
index 41a3316..e22b460 100644
--- a/tcp_input.c
+++ b/tcp_input.c
@@ -255,6 +255,7 @@ struct socket *inso;
     u_long tiwin;
     int ret;
     /*	int ts_present = 0; */
+    struct ex_list *ex_ptr;
 
     DEBUG_CALL("tcp_input");
     DEBUG_ARGS((dfd, " m = %8lx  iphlen = %2d  inso = %lx\n", (long)m, iphlen,
@@ -365,6 +366,15 @@ struct socket *inso;
     m->m_data += sizeof(struct tcpiphdr) + off - sizeof(struct tcphdr);
     m->m_len -= sizeof(struct tcpiphdr) + off - sizeof(struct tcphdr);
 
+    if (slirp_restrict) {
+        for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
+            if (ex_ptr->ex_fport == ti->ti_dport &&
+                (ntohl(ti->ti_dst.s_addr) & 0xff) == ex_ptr->ex_addr)
+                break;
+
+        if (!ex_ptr)
+            goto drop;
+    }
     /*
      * Locate pcb for segment.
      */
@@ -645,7 +655,6 @@ findso:
 #endif
                 {
                     /* May be an add exec */
-                    struct ex_list *ex_ptr;
                     for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next) {
                         if (ex_ptr->ex_fport == so->so_fport &&
                             lastbyte == ex_ptr->ex_addr) {
diff --git a/udp.c b/udp.c
index c97d07d..033bd2f 100644
--- a/udp.c
+++ b/udp.c
@@ -155,6 +155,9 @@ int iphlen;
         goto bad;
     }
 
+    if (slirp_restrict)
+        goto bad;
+
     /*
      *  handle TFTP
      */