From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 17/20] netfilter: nfnetlink: Remove VLA usage
Date: Sat, 2 Jun 2018 02:22:56 +0200 [thread overview]
Message-ID: <20180602002259.4024-18-pablo@netfilter.org> (raw)
In-Reply-To: <20180602002259.4024-1-pablo@netfilter.org>
From: Kees Cook <keescook@chromium.org>
In the quest to remove all stack VLA usage from the kernel[1], this
allocates the maximum size expected for all possible attrs and adds
sanity-checks at both registration and usage to make sure nothing
gets out of sync.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/netfilter/nfnetlink.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 261820627711..4d0da7042aff 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -38,6 +38,8 @@ MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
rcu_dereference_protected(table[(id)].subsys, \
lockdep_nfnl_is_held((id)))
+#define NFNL_MAX_ATTR_COUNT 32
+
static struct {
struct mutex mutex;
const struct nfnetlink_subsystem __rcu *subsys;
@@ -77,6 +79,13 @@ EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
{
+ u8 cb_id;
+
+ /* Sanity-check attr_count size to avoid stack buffer overflow. */
+ for (cb_id = 0; cb_id < n->cb_count; cb_id++)
+ if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
+ return -EINVAL;
+
nfnl_lock(n->subsys_id);
if (table[n->subsys_id].subsys) {
nfnl_unlock(n->subsys_id);
@@ -186,11 +195,17 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
{
int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
- struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
+ struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
struct nlattr *attr = (void *)nlh + min_len;
int attrlen = nlh->nlmsg_len - min_len;
__u8 subsys_id = NFNL_SUBSYS_ID(type);
+ /* Sanity-check NFNL_MAX_ATTR_COUNT */
+ if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
+ rcu_read_unlock();
+ return -ENOMEM;
+ }
+
err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen,
ss->cb[cb_id].policy, extack);
if (err < 0) {
@@ -387,10 +402,16 @@ static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
{
int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
- struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
+ struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
struct nlattr *attr = (void *)nlh + min_len;
int attrlen = nlh->nlmsg_len - min_len;
+ /* Sanity-check NFTA_MAX_ATTR */
+ if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
+ err = -ENOMEM;
+ goto ack;
+ }
+
err = nla_parse(cda, ss->cb[cb_id].attr_count, attr,
attrlen, ss->cb[cb_id].policy, NULL);
if (err < 0)
--
2.11.0
next prev parent reply other threads:[~2018-06-02 0:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-02 0:22 [PATCH 00/20] Netfilter/IPVS updates for net-next Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 01/20] netfilter: add includes to nf_socket.h Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 02/20] netfilter: nat: merge ipv4/ipv6 masquerade code into main nat module Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 03/20] netfilter: nat: merge nf_nat_redirect into nf_nat Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 04/20] netfilter: nfnetlink: allow commit to fail Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 05/20] netfilter: nf_tables: remove synchronize_rcu in commit phase Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 06/20] netfilter: nat: make symbol nat_hook static Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 07/20] netfilter: nft_compat: use call_rcu for nfnl_compat_get Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 08/20] netfilter: nf_tables: fix endian mismatch in return type Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 09/20] netfilter: nf_tables: fail batch if fatal signal is pending Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 10/20] netfilter: nf_tables: use call_rcu in netlink dumps Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 11/20] netfilter: nf_tables: remove unused variables Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 12/20] netfilter: fix ptr_ret.cocci warnings Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 13/20] netfilter: nf_tables: add support for native socket matching Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 14/20] netfilter: nf_tables: Add audit support to log statement Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 15/20] netfilter: nf_tables: fix chain dependency validation Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 16/20] netfilter: nf_flow_table: attach dst to skbs Pablo Neira Ayuso
2018-06-02 0:22 ` Pablo Neira Ayuso [this message]
2018-06-02 0:22 ` [PATCH 18/20] netfilter: nft_fwd_netdev: allow to forward packets via neighbour layer Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 19/20] ipvs: add full ipv6 support to nfct Pablo Neira Ayuso
2018-06-02 0:22 ` [PATCH 20/20] ipvs: add ipv6 support to ftp Pablo Neira Ayuso
2018-06-02 13:04 ` [PATCH 00/20] Netfilter/IPVS updates for net-next David Miller
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