linux-kernel - [PATCH AUTOSEL for 4.9 077/190] netfilter: nf_ct_helper: permit cthelpers with different names via nfnetlink

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180308045810.8041-77-alexander.levin@microsoft.com>
Date:   Thu, 8 Mar 2018 04:59:25 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Liping Zhang <zlpnobody@...il.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.9 077/190] netfilter: nf_ct_helper: permit
 cthelpers with different names via nfnetlink

From: Liping Zhang <zlpnobody@...il.com>

[ Upstream commit 66e5a6b18bd09d0431e97cd3c162e76c5c2aebba ]

cthelpers added via nfnetlink may have the same tuple, i.e. except for
the l3proto and l4proto, other fields are all zero. So even with the
different names, we will also fail to add them:
  # nfct helper add ssdp inet udp
  # nfct helper add tftp inet udp
  nfct v1.4.3: netlink error: File exists

So in order to avoid unpredictable behaviour, we should:
1. cthelpers can be selected by nft ct helper obj or xt_CT target, so
report error if duplicated { name, l3proto, l4proto } tuple exist.
2. cthelpers can be selected by nf_ct_tuple_src_mask_cmp when
nf_ct_auto_assign_helper is enabled, so also report error if duplicated
{ l3proto, l4proto, src-port } tuple exist.

Also note, if the cthelper is added from userspace, then the src-port will
always be zero, it's invalid for nf_ct_auto_assign_helper, so there's no
need to check the second point listed above.

Fixes: 893e093c786c ("netfilter: nf_ct_helper: bail out on duplicated helpers")
Signed-off-by: Liping Zhang <zlpnobody@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 net/netfilter/nf_conntrack_helper.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 6dc44d9b4190..92e69af41656 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -379,17 +379,33 @@ int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
 	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
 	unsigned int h = helper_hash(&me->tuple);
 	struct nf_conntrack_helper *cur;
-	int ret = 0;
+	int ret = 0, i;
 
 	BUG_ON(me->expect_policy == NULL);
 	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
 	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
 
 	mutex_lock(&nf_ct_helper_mutex);
-	hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
-		if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple, &mask)) {
-			ret = -EEXIST;
-			goto out;
+	for (i = 0; i < nf_ct_helper_hsize; i++) {
+		hlist_for_each_entry(cur, &nf_ct_helper_hash[i], hnode) {
+			if (!strcmp(cur->name, me->name) &&
+			    (cur->tuple.src.l3num == NFPROTO_UNSPEC ||
+			     cur->tuple.src.l3num == me->tuple.src.l3num) &&
+			    cur->tuple.dst.protonum == me->tuple.dst.protonum) {
+				ret = -EEXIST;
+				goto out;
+			}
+		}
+	}
+
+	/* avoid unpredictable behaviour for auto_assign_helper */
+	if (!(me->flags & NF_CT_HELPER_F_USERSPACE)) {
+		hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
+			if (nf_ct_tuple_src_mask_cmp(&cur->tuple, &me->tuple,
+						     &mask)) {
+				ret = -EEXIST;
+				goto out;
+			}
 		}
 	}
 	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
-- 
2.14.1