lwtunnel: Validate RTA_ENCAP_TYPE attribute length

lwtunnel_valid_encap_type_attr is used to validate encap attributes
within a multipath route. Add length validation checking to the type.

lwtunnel_valid_encap_type_attr is called converting attributes to
fib{6,}_config struct which means it is used before fib_get_nhs,
ip6_route_multipath_add, and ip6_route_multipath_del - other
locations that use rtnh_ok and then nla_get_u16 on RTA_ENCAP_TYPE
attribute.

Fixes: 9ed59592e3e3 ("lwtunnel: fix autoload of lwt modules")

Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 2820aca..9ccd64e 100644 (file)
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -197,6 +197,10 @@ int lwtunnel_valid_encap_type_attr(struct nlattr *attr, int remaining,
                        nla_entype = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
 
                        if (nla_entype) {
+                               if (nla_len(nla_entype) < sizeof(u16)) {
+                                       NL_SET_ERR_MSG(extack, "Invalid RTA_ENCAP_TYPE");
+                                       return -EINVAL;
+                               }
                                encap_type = nla_get_u16(nla_entype);
 
                                if (lwtunnel_valid_encap_type(encap_type,

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 36bc429..92c29ab 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -740,6 +740,9 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
                        }
 
                        fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
+                       /* RTA_ENCAP_TYPE length checked in
+                        * lwtunnel_valid_encap_type_attr
+                        */
                        nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
                        if (nla)
                                fib_cfg.fc_encap_type = nla_get_u16(nla);

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index b311c0b..d2ff8a7 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5287,6 +5287,10 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
                                r_cfg.fc_flags |= RTF_GATEWAY;
                        }
                        r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
+
+                       /* RTA_ENCAP_TYPE length checked in
+                        * lwtunnel_valid_encap_type_attr
+                        */
                        nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
                        if (nla)
                                r_cfg.fc_encap_type = nla_get_u16(nla);