[IPV6]: Disallow RH0 by default.

A security issue is emerging.  Disallow Routing Header Type 0 by default
as we have been doing for IPv4.
Note: We allow RH2 by default because it is harmless.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 58 insertions, 6 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index d3aae1f9b4c1..702d1d8dd04a 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -851,6 +851,15 @@ accept_redirects - BOOLEAN
         Functional default: enabled if local forwarding is disabled.
                             disabled if local forwarding is enabled.
 
+accept_source_route - INTEGER
+        Accept source routing (routing extension header).
+
+        > 0: Accept routing header.
+        = 0: Accept only routing header type 2.
+        < 0: Do not accept routing header.
+
+        Default: 0
+
 autoconf - BOOLEAN
         Autoconfigure addresses using Prefix Information in Router 
         Advertisements.
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index f8241130f5ea..713eb5eaa81f 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -177,6 +177,7 @@ struct ipv6_devconf {
 #endif
 #endif
         __s32           proxy_ndp;
+        __s32           accept_source_route;
         void            *sysctl;
 };
 
@@ -205,6 +206,8 @@ enum {
         DEVCONF_RTR_PROBE_INTERVAL,
         DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN,
         DEVCONF_PROXY_NDP,
+        __DEVCONF_OPTIMISTIC_DAD,
+        DEVCONF_ACCEPT_SOURCE_ROUTE,
         DEVCONF_MAX
 };
 
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 2c5fb38d9392..9a8970bf99a6 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -580,6 +580,7 @@ enum {
         NET_IPV6_RTR_PROBE_INTERVAL=21,
         NET_IPV6_ACCEPT_RA_RT_INFO_MAX_PLEN=22,
         NET_IPV6_PROXY_NDP=23,
+        NET_IPV6_ACCEPT_SOURCE_ROUTE=25,
         __NET_IPV6_MAX
 };
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 7552663aa125..452a82ce4796 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -172,6 +172,7 @@ struct ipv6_devconf ipv6_devconf __read_mostly = {
 #endif
 #endif
         .proxy_ndp              = 0,
+        .accept_source_route    = 0,    /* we do not accept RH0 by default. */
 };
 
 static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
@@ -203,6 +204,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = {
 #endif
 #endif
         .proxy_ndp              = 0,
+        .accept_source_route    = 0,    /* we do not accept RH0 by default. */
 };
 
 /* IPv6 Wildcard Address and Loopback Address defined by RFC2553 */
@@ -3356,6 +3358,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
 #endif
 #endif
         array[DEVCONF_PROXY_NDP] = cnf->proxy_ndp;
+        array[DEVCONF_ACCEPT_SOURCE_ROUTE] = cnf->accept_source_route;
 }
 
 static inline size_t inet6_if_nlmsg_size(void)
@@ -3884,6 +3887,14 @@ static struct addrconf_sysctl_table
                         .proc_handler   =       &proc_dointvec,
                 },
                 {
+                        .ctl_name       =       NET_IPV6_ACCEPT_SOURCE_ROUTE,
+                        .procname       =       "accept_source_route",
+                        .data           =       &ipv6_devconf.accept_source_route,
+                        .maxlen         =       sizeof(int),
+                        .mode           =       0644,
+                        .proc_handler   =       &proc_dointvec,
+                },
+                {
                         .ctl_name       =       0,      /* sentinel */
                 }
         },
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 28e0c6568272..6ed6a8cd6a68 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -362,10 +362,27 @@ static int ipv6_rthdr_rcv(struct sk_buff **skbp)
         struct inet6_skb_parm *opt = IP6CB(skb);
         struct in6_addr *addr = NULL;
         struct in6_addr daddr;
+        struct inet6_dev *idev;
         int n, i;
-
         struct ipv6_rt_hdr *hdr;
         struct rt0_hdr *rthdr;
+        int accept_source_route = ipv6_devconf.accept_source_route;
+
+        if (accept_source_route < 0 ||
+            ((idev = in6_dev_get(skb->dev)) == NULL)) {
+                kfree_skb(skb);
+                return -1;
+        }
+        if (idev->cnf.accept_source_route < 0) {
+                in6_dev_put(idev);
+                kfree_skb(skb);
+                return -1;
+        }
+
+        if (accept_source_route > idev->cnf.accept_source_route)
+                accept_source_route = idev->cnf.accept_source_route;
+
+        in6_dev_put(idev);
 
         if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
             !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
@@ -377,6 +394,22 @@ static int ipv6_rthdr_rcv(struct sk_buff **skbp)
 
         hdr = (struct ipv6_rt_hdr *) skb->h.raw;
 
+        switch (hdr->type) {
+#ifdef CONFIG_IPV6_MIP6
+                break;
+#endif
+        case IPV6_SRCRT_TYPE_0:
+                if (accept_source_route <= 0)
+                        break;
+                kfree_skb(skb);
+                return -1;
+        default:
+                IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
+                                 IPSTATS_MIB_INHDRERRORS);
+                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
+                return -1;
+        }
+
         if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr) ||
             skb->pkt_type != PACKET_HOST) {
                 IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
@@ -434,11 +467,6 @@ looped_back:
                 }
                 break;
 #endif
-        default:
-                IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
-                                 IPSTATS_MIB_INHDRERRORS);
-                icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
-                return -1;
         }
 
         /*