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authorPablo Neira Ayuso <pablo@netfilter.org>2020-01-21 16:07:00 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2020-01-24 20:54:28 +0100
commit826035498ec14b77b62a44f0cb6b94d45530db6f (patch)
tree22dcb670215ae5c943d1fcd2ba8780bb1dbca885
parentc83de17dd6308fb74696923e5245de0e3c427206 (diff)
downloadlinux-826035498ec14b77b62a44f0cb6b94d45530db6f.tar.gz
netfilter: nf_tables: add __nft_chain_type_get()
This new helper function validates that unknown family and chain type coming from userspace do not trigger an out-of-bound array access. Bail out in case __nft_chain_type_get() returns NULL from nft_chain_parse_hook(). Fixes: 9370761c56b6 ("netfilter: nf_tables: convert built-in tables/chains to chain types") Reported-by: syzbot+156a04714799b1d480bc@syzkaller.appspotmail.com Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
-rw-r--r--net/netfilter/nf_tables_api.c29
1 files changed, 21 insertions, 8 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 65f51a2e9c2a..4aa01c1253b1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -553,14 +553,27 @@ static inline u64 nf_tables_alloc_handle(struct nft_table *table)
static const struct nft_chain_type *chain_type[NFPROTO_NUMPROTO][NFT_CHAIN_T_MAX];
static const struct nft_chain_type *
+__nft_chain_type_get(u8 family, enum nft_chain_types type)
+{
+ if (family >= NFPROTO_NUMPROTO ||
+ type >= NFT_CHAIN_T_MAX)
+ return NULL;
+
+ return chain_type[family][type];
+}
+
+static const struct nft_chain_type *
__nf_tables_chain_type_lookup(const struct nlattr *nla, u8 family)
{
+ const struct nft_chain_type *type;
int i;
for (i = 0; i < NFT_CHAIN_T_MAX; i++) {
- if (chain_type[family][i] != NULL &&
- !nla_strcmp(nla, chain_type[family][i]->name))
- return chain_type[family][i];
+ type = __nft_chain_type_get(family, i);
+ if (!type)
+ continue;
+ if (!nla_strcmp(nla, type->name))
+ return type;
}
return NULL;
}
@@ -1162,11 +1175,8 @@ static void nf_tables_table_destroy(struct nft_ctx *ctx)
void nft_register_chain_type(const struct nft_chain_type *ctype)
{
- if (WARN_ON(ctype->family >= NFPROTO_NUMPROTO))
- return;
-
nfnl_lock(NFNL_SUBSYS_NFTABLES);
- if (WARN_ON(chain_type[ctype->family][ctype->type] != NULL)) {
+ if (WARN_ON(__nft_chain_type_get(ctype->family, ctype->type))) {
nfnl_unlock(NFNL_SUBSYS_NFTABLES);
return;
}
@@ -1768,7 +1778,10 @@ static int nft_chain_parse_hook(struct net *net,
hook->num = ntohl(nla_get_be32(ha[NFTA_HOOK_HOOKNUM]));
hook->priority = ntohl(nla_get_be32(ha[NFTA_HOOK_PRIORITY]));
- type = chain_type[family][NFT_CHAIN_T_DEFAULT];
+ type = __nft_chain_type_get(family, NFT_CHAIN_T_DEFAULT);
+ if (!type)
+ return -EOPNOTSUPP;
+
if (nla[NFTA_CHAIN_TYPE]) {
type = nf_tables_chain_type_lookup(net, nla[NFTA_CHAIN_TYPE],
family, autoload);