Re: [PATCH nf-next 1/1] netfilter: ctlink: Return error directly when create expect without help

[Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>]

On Tue, Mar 28, 2017 at 09:52:52AM +0800, gfree.wind@xxxxxxxxxxx wrote:
> From: Gao Feng <fgao@xxxxxxxxxx>
> 
> The expect check func "__nf_ct_expect_check" asks the master_help is
> necessary. So it is unnecessary to go ahead in ctnetlink_alloc_expect
> when there is no help.
> 
> Actually the commit bc01befdcf3e ("netfilter: ctnetlink: add support
> for user-space expectation helpers") permits ctlink create one expect
> even though there is no master help. But the latter commit 3d058d7bc2c5
> ("netfilter: rework user-space expectation helper support") disables
> it again.

Probably reject this upfront if no nfct_help(ct) is there.

See patch attached.

commit 543b8a39eaacef70822f23f8e8de336c18761c40
Author: Gao Feng <fgao@xxxxxxxxxx>
Date:   Tue Mar 28 09:52:52 2017 +0800

    netfilter: ctnetlink: Expectations must have a conntrack helper area
    
    The expect check function __nf_ct_expect_check() asks the master_help
    is necessary. So it is unnecessary to go ahead in ctnetlink_alloc_expect
    when there is no help.
    
    Actually the commit bc01befdcf3e ("netfilter: ctnetlink: add support
    for user-space expectation helpers") permits ctnetlink create one expect
    even though there is no master help. But the latter commit 3d058d7bc2c5
    ("netfilter: rework user-space expectation helper support") disables
    it again.
    
    Signed-off-by: Gao Feng <fgao@xxxxxxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index ecdc324c7785..cd0a6d270ebe 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -3038,6 +3038,10 @@ ctnetlink_alloc_expect(const struct nlattr * const cda[], struct nf_conn *ct,
 	struct nf_conn_help *help;
 	int err;
 
+	help = nfct_help(ct);
+	if (!help)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	if (cda[CTA_EXPECT_CLASS] && helper) {
 		class = ntohl(nla_get_be32(cda[CTA_EXPECT_CLASS]));
 		if (class > helper->expect_class_max)
@@ -3047,26 +3051,11 @@ ctnetlink_alloc_expect(const struct nlattr * const cda[], struct nf_conn *ct,
 	if (!exp)
 		return ERR_PTR(-ENOMEM);
 
-	help = nfct_help(ct);
-	if (!help) {
-		if (!cda[CTA_EXPECT_TIMEOUT]) {
-			err = -EINVAL;
-			goto err_out;
-		}
-		exp->timeout.expires =
-		  jiffies + ntohl(nla_get_be32(cda[CTA_EXPECT_TIMEOUT])) * HZ;
-
-		exp->flags = NF_CT_EXPECT_USERSPACE;
-		if (cda[CTA_EXPECT_FLAGS]) {
-			exp->flags |=
-				ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS]));
-		}
+	if (cda[CTA_EXPECT_FLAGS]) {
+		exp->flags = ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS]));
+		exp->flags &= ~NF_CT_EXPECT_USERSPACE;
 	} else {
-		if (cda[CTA_EXPECT_FLAGS]) {
-			exp->flags = ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS]));
-			exp->flags &= ~NF_CT_EXPECT_USERSPACE;
-		} else
-			exp->flags = 0;
+		exp->flags = 0;
 	}
 	if (cda[CTA_EXPECT_FN]) {
 		const char *name = nla_data(cda[CTA_EXPECT_FN]);