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

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

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

1 files changed, 39 insertions, 4 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index e258a00b4a3d..cd027639df2f 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2063,13 +2063,49 @@ static const struct nla_policy devconf_ipv4_policy[NETCONFA_MAX+1] = {
         [NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN]  = { .len = sizeof(int) },
 };
 
+static int inet_netconf_valid_get_req(struct sk_buff *skb,
+                                      const struct nlmsghdr *nlh,
+                                      struct nlattr **tb,
+                                      struct netlink_ext_ack *extack)
+{
+        int i, err;
+
+        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(struct netconfmsg))) {
+                NL_SET_ERR_MSG(extack, "ipv4: Invalid header for netconf get request");
+                return -EINVAL;
+        }
+
+        if (!netlink_strict_get_check(skb))
+                return nlmsg_parse(nlh, sizeof(struct netconfmsg), tb,
+                                   NETCONFA_MAX, devconf_ipv4_policy, extack);
+
+        err = nlmsg_parse_strict(nlh, sizeof(struct netconfmsg), tb,
+                                 NETCONFA_MAX, devconf_ipv4_policy, extack);
+        if (err)
+                return err;
+
+        for (i = 0; i <= NETCONFA_MAX; i++) {
+                if (!tb[i])
+                        continue;
+
+                switch (i) {
+                case NETCONFA_IFINDEX:
+                        break;
+                default:
+                        NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in netconf get request");
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
 static int inet_netconf_get_devconf(struct sk_buff *in_skb,
                                     struct nlmsghdr *nlh,
                                     struct netlink_ext_ack *extack)
 {
         struct net *net = sock_net(in_skb->sk);
         struct nlattr *tb[NETCONFA_MAX+1];
-        struct netconfmsg *ncm;
         struct sk_buff *skb;
         struct ipv4_devconf *devconf;
         struct in_device *in_dev;
@@ -2077,9 +2113,8 @@ static int inet_netconf_get_devconf(struct sk_buff *in_skb,
         int ifindex;
         int err;
 
-        err = nlmsg_parse(nlh, sizeof(*ncm), tb, NETCONFA_MAX,
-                          devconf_ipv4_policy, extack);
-        if (err < 0)
+        err = inet_netconf_valid_get_req(in_skb, nlh, tb, extack);
+        if (err)
                 goto errout;
 
         err = -EINVAL;