[Qemu-devel] [PATCH 1/9] slirp: Fix restricted mode

[Jan Kiszka]

This aligns the code to what the documentation claims: Allow everything
but requests that would have to be routed outside of the virtual LAN.

So we need to drop the unneeded IP-level filter, allow TFTP requests,
and add the missing protocol-level filter to ICMP.

CC: Gleb Natapov <g...@redhat.com>
Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---
 slirp/ip_icmp.c  |    2 ++
 slirp/ip_input.c |   21 ---------------------
 slirp/udp.c      |    8 ++++----
 3 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
index 751a8e2..0cd129c 100644
--- a/slirp/ip_icmp.c
+++ b/slirp/ip_icmp.c
@@ -101,6 +101,8 @@ icmp_input(struct mbuf *m, int hlen)
     ip->ip_len += hlen;                     /* since ip_input subtracts this */
     if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
       icmp_reflect(m);
+    } else if (slirp->restricted) {
+        goto freeit;
     } else {
       struct socket *so;
       struct sockaddr_in addr;
diff --git a/slirp/ip_input.c b/slirp/ip_input.c
index 768ab0c..2ff6adb 100644
--- a/slirp/ip_input.c
+++ b/slirp/ip_input.c
@@ -118,27 +118,6 @@ ip_input(struct mbuf *m)
                goto bad;
        }
 
-    if (slirp->restricted) {
-        if ((ip->ip_dst.s_addr & slirp->vnetwork_mask.s_addr) ==
-            slirp->vnetwork_addr.s_addr) {
-            if (ip->ip_dst.s_addr == 0xffffffff && ip->ip_p != IPPROTO_UDP)
-                goto bad;
-        } else {
-            uint32_t inv_mask = ~slirp->vnetwork_mask.s_addr;
-            struct ex_list *ex_ptr;
-
-            if ((ip->ip_dst.s_addr & inv_mask) == inv_mask) {
-                goto bad;
-            }
-            for (ex_ptr = slirp->exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
-                if (ex_ptr->ex_addr.s_addr == ip->ip_dst.s_addr)
-                    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/slirp/udp.c b/slirp/udp.c
index 02b3793..f1a9a10 100644
--- a/slirp/udp.c
+++ b/slirp/udp.c
@@ -125,10 +125,6 @@ udp_input(register struct mbuf *m, int iphlen)
             goto bad;
         }
 
-        if (slirp->restricted) {
-            goto bad;
-        }
-
         /*
          *  handle TFTP
          */
@@ -137,6 +133,10 @@ udp_input(register struct mbuf *m, int iphlen)
             goto bad;
         }
 
+        if (slirp->restricted) {
+            goto bad;
+        }
+
        /*
         * Locate pcb for datagram.
         */
-- 
1.7.1