[PATCH net-next v2 06/14] net: ipv4: netconf: perform strict checks also for doit handlers

[Jakub Kicinski]

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

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 net/ipv4/devinet.c | 43 +++++++++++++++++++++++++++++++++++++++----
 1 file 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;
-- 
2.19.2