net: ipv4: ipmr: perform strict checks also for doit handlers

Make RTM_GETROUTE's doit handler use strict checks when
NETLINK_F_STRICT_CHK is set.

v2: - improve extack messages (DaveA).

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index ddbf8c9a1abb8e34d0d34f2903afea5ce5db96a7..fb99002c3d4e8523f2aa7926fee41ea8272bdb76 100644 (file)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -2467,6 +2467,61 @@ errout:
        rtnl_set_sk_err(net, RTNLGRP_IPV4_MROUTE_R, -ENOBUFS);
 }
 
+static int ipmr_rtm_valid_getroute_req(struct sk_buff *skb,
+                                      const struct nlmsghdr *nlh,
+                                      struct nlattr **tb,
+                                      struct netlink_ext_ack *extack)
+{
+       struct rtmsg *rtm;
+       int i, err;
+
+       if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
+               NL_SET_ERR_MSG(extack, "ipv4: Invalid header for multicast route get request");
+               return -EINVAL;
+       }
+
+       if (!netlink_strict_get_check(skb))
+               return nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX,
+                                  rtm_ipv4_policy, extack);
+
+       rtm = nlmsg_data(nlh);
+       if ((rtm->rtm_src_len && rtm->rtm_src_len != 32) ||
+           (rtm->rtm_dst_len && rtm->rtm_dst_len != 32) ||
+           rtm->rtm_tos || rtm->rtm_table || rtm->rtm_protocol ||
+           rtm->rtm_scope || rtm->rtm_type || rtm->rtm_flags) {
+               NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for multicast route get request");
+               return -EINVAL;
+       }
+
+       err = nlmsg_parse_strict(nlh, sizeof(*rtm), tb, RTA_MAX,
+                                rtm_ipv4_policy, extack);
+       if (err)
+               return err;
+
+       if ((tb[RTA_SRC] && !rtm->rtm_src_len) ||
+           (tb[RTA_DST] && !rtm->rtm_dst_len)) {
+               NL_SET_ERR_MSG(extack, "ipv4: rtm_src_len and rtm_dst_len must be 32 for IPv4");
+               return -EINVAL;
+       }
+
+       for (i = 0; i <= RTA_MAX; i++) {
+               if (!tb[i])
+                       continue;
+
+               switch (i) {
+               case RTA_SRC:
+               case RTA_DST:
+               case RTA_TABLE:
+                       break;
+               default:
+                       NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in multicast route get request");
+                       return -EINVAL;
+               }
+       }
+
+       return 0;
+}
+
 static int ipmr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
 {
@@ -2475,18 +2530,14 @@ static int ipmr_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
        struct sk_buff *skb = NULL;
        struct mfc_cache *cache;
        struct mr_table *mrt;
-       struct rtmsg *rtm;
        __be32 src, grp;
        u32 tableid;
        int err;
 
-       err = nlmsg_parse(nlh, sizeof(*rtm), tb, RTA_MAX,
-                         rtm_ipv4_policy, extack);
+       err = ipmr_rtm_valid_getroute_req(in_skb, nlh, tb, extack);
        if (err < 0)
                goto errout;
 
-       rtm = nlmsg_data(nlh);
-
        src = tb[RTA_SRC] ? nla_get_in_addr(tb[RTA_SRC]) : 0;
        grp = tb[RTA_DST] ? nla_get_in_addr(tb[RTA_DST]) : 0;
        tableid = tb[RTA_TABLE] ? nla_get_u32(tb[RTA_TABLE]) : 0;