[PATCH 4.14 159/217] netfilter: nft_compat: explicitly reject ERROR and standard target

Greg Kroah-Hartman
2018-08-23T08:31:00Z

From: Florian Westphal <fw@strlen.de>

[ Upstream commit 21d5e078192d244df3d6049f9464fff2f72cfd68 ]

iptables-nft never requests these, but make this explicitly illegal.
If it were quested, kernel could oops as ->eval is NULL, furthermore,
the builtin targets have no owning module so its possible to rmmod
eb/ip/ip6_tables module even if they would be loaded.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/nft_compat.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

--- a/net/netfilter/nft_compat.c
+++ b/net/netfilter/nft_compat.c
@@ -825,10 +825,18 @@ nft_target_select_ops(const struct nft_c
rev = ntohl(nla_get_be32(tb[NFTA_TARGET_REV]));
family = ctx->afi->family;

+ if (strcmp(tg_name, XT_ERROR_TARGET) == 0 ||
+ strcmp(tg_name, XT_STANDARD_TARGET) == 0 ||
+ strcmp(tg_name, "standard") == 0)
+ return ERR_PTR(-EINVAL);
+
/* Re-use the existing target if it's already loaded. */
list_for_each_entry(nft_target, &nft_target_list, head) {
struct xt_target *target = nft_target->ops.data;

+ if (!target->target)
+ continue;
+
if (nft_target_cmp(target, tg_name, rev, family))
return &nft_target->ops;
}
@@ -837,6 +845,11 @@ nft_target_select_ops(const struct nft_c
if (IS_ERR(target))
return ERR_PTR(-ENOENT);

+ if (!target->target) {
+ err = -EINVAL;
+ goto err;
+ }
+
if (target->targetsize > nla_len(tb[NFTA_TARGET_INFO])) {
err = -EINVAL;
goto err;