netdev - Re: [PATCH net] net/route: remove ip route rtm_src_len, rtm_dst

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Message-ID: <20200111011835.GG2159@dhcp-12-139.nay.redhat.com>
Date:   Sat, 11 Jan 2020 09:18:35 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH net] net/route: remove ip route rtm_src_len, rtm_dst_len
 valid check

On Fri, Jan 10, 2020 at 02:48:03PM -0700, David Ahern wrote:
> On 1/10/20 1:24 AM, Hangbin Liu wrote:
> > In patch set e266afa9c7af ("Merge branch
> > 'net-use-strict-checks-in-doit-handlers'") we added a check for
> > rtm_src_len, rtm_dst_len, which will cause cmds like
> > "ip route get 192.0.2.0/24" failed.
> 
> kernel does not handle route gets for a range. Any output is specific to
> the prefix (192.0.2.0 in your example) so it seems to me the /24 request
> should fail.
> 

OK, so we should check all the range field if NETLINK_F_STRICT_CHK supplied,
like the following patch, right?


diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 87e979f2b74a..a681c5cfbf13 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3063,8 +3063,7 @@ static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
 					      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) ||
+	if (rtm->rtm_src_len || rtm->rtm_dst_len ||
 	    rtm->rtm_table || rtm->rtm_protocol ||
 	    rtm->rtm_scope || rtm->rtm_type) {
 		NL_SET_ERR_MSG(extack, "ipv4: Invalid values in header for route get request");
@@ -3083,12 +3082,6 @@ static int inet_rtm_valid_getroute_req(struct sk_buff *skb,
 	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;


Thanks
Hangbin