Merge branch 'mpr-len-checks'

David Ahern says: ==================== net: Length checks for attributes within multipath routes Add length checks for attributes within a multipath route (attributes within RTA_MULTIPATH). Motivated by the syzbot report in patch 1 and then expanded to other attributes as noted by Ido. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
mariux64 · Dec 31, 2021 · 4760aba · 4760aba
2 parents 74c78b4 + 8bda81a
commit 4760aba
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Showing 3 changed files with 76 additions and 8 deletions.
diff --git 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
@@ -662,6 +662,19 @@ static int fib_count_nexthops(struct rtnexthop *rtnh, int remaining,
 	return nhs;
 }
 
+static int fib_gw_from_attr(__be32 *gw, struct nlattr *nla,
+			    struct netlink_ext_ack *extack)
+{
+	if (nla_len(nla) < sizeof(*gw)) {
+		NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_GATEWAY");
+		return -EINVAL;
+	}
+
+	*gw = nla_get_in_addr(nla);
+
+	return 0;
+}
+
 /* only called when fib_nh is integrated into fib_info */
 static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 		       int remaining, struct fib_config *cfg,
@@ -704,7 +717,11 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 				return -EINVAL;
 			}
 			if (nla) {
-				fib_cfg.fc_gw4 = nla_get_in_addr(nla);
+				ret = fib_gw_from_attr(&fib_cfg.fc_gw4, nla,
+						       extack);
+				if (ret)
+					goto errout;
+
 				if (fib_cfg.fc_gw4)
 					fib_cfg.fc_gw_family = AF_INET;
 			} else if (nlav) {
@@ -714,10 +731,18 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 			}
 
 			nla = nla_find(attrs, attrlen, RTA_FLOW);
-			if (nla)
+			if (nla) {
+				if (nla_len(nla) < sizeof(u32)) {
+					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+					return -EINVAL;
+				}
 				fib_cfg.fc_flow = nla_get_u32(nla);
+			}
 
 			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);
@@ -902,6 +927,7 @@ int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 		attrlen = rtnh_attrlen(rtnh);
 		if (attrlen > 0) {
 			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);
+			int err;
 
 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 			nlav = nla_find(attrs, attrlen, RTA_VIA);
@@ -912,12 +938,17 @@ int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 			}
 
 			if (nla) {
+				__be32 gw;
+
+				err = fib_gw_from_attr(&gw, nla, extack);
+				if (err)
+					return err;
+
 				if (nh->fib_nh_gw_family != AF_INET ||
-				    nla_get_in_addr(nla) != nh->fib_nh_gw4)
+				    gw != nh->fib_nh_gw4)
 					return 1;
 			} else if (nlav) {
 				struct fib_config cfg2;
-				int err;
 
 				err = fib_gw_from_via(&cfg2, nlav, extack);
 				if (err)
@@ -940,8 +971,14 @@ int fib_nh_match(struct net *net, struct fib_config *cfg, struct fib_info *fi,
 
 #ifdef CONFIG_IP_ROUTE_CLASSID
 			nla = nla_find(attrs, attrlen, RTA_FLOW);
-			if (nla && nla_get_u32(nla) != nh->nh_tclassid)
-				return 1;
+			if (nla) {
+				if (nla_len(nla) < sizeof(u32)) {
+					NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+					return -EINVAL;
+				}
+				if (nla_get_u32(nla) != nh->nh_tclassid)
+					return 1;
+			}
 #endif
 		}
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
@@ -5224,6 +5224,19 @@ static bool ip6_route_mpath_should_notify(const struct fib6_info *rt)
 	return should_notify;
 }
 
+static int fib6_gw_from_attr(struct in6_addr *gw, struct nlattr *nla,
+			     struct netlink_ext_ack *extack)
+{
+	if (nla_len(nla) < sizeof(*gw)) {
+		NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_GATEWAY");
+		return -EINVAL;
+	}
+
+	*gw = nla_get_in6_addr(nla);
+
+	return 0;
+}
+
 static int ip6_route_multipath_add(struct fib6_config *cfg,
 				   struct netlink_ext_ack *extack)
 {
@@ -5264,10 +5277,20 @@ static int ip6_route_multipath_add(struct fib6_config *cfg,
 
 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 			if (nla) {
-				r_cfg.fc_gateway = nla_get_in6_addr(nla);
+				int ret;
+
+				ret = fib6_gw_from_attr(&r_cfg.fc_gateway, nla,
+							extack);
+				if (ret)
+					return ret;
+
 				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);
@@ -5434,7 +5457,11 @@ static int ip6_route_multipath_del(struct fib6_config *cfg,
 
 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
 			if (nla) {
-				nla_memcpy(&r_cfg.fc_gateway, nla, 16);
+				err = fib6_gw_from_attr(&r_cfg.fc_gateway, nla,
+							extack);
+				if (err)
+					return err;
+
 				r_cfg.fc_flags |= RTF_GATEWAY;
 			}
 		}