[PATCH 4.19 062/103] netfilter: nf_tables: remove WARN and add NLA_STRING upper limits

Greg Kroah-Hartman
2020-01-22T09:44:01Z

From: Florian Westphal <fw@strlen.de>

commit 9332d27d7918182add34e8043f6a754530fdd022 upstream.

This WARN can trigger because some of the names fed to the module
autoload function can be of arbitrary length.

Remove the WARN and add limits for all NLA_STRING attributes.

Reported-by: syzbot+0e63ae76d117ae1c3a01@syzkaller.appspotmail.com
Fixes: 452238e8d5ffd8 ("netfilter: nf_tables: add and use helper for module autoload")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/netfilter/nf_tables_api.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -24,6 +24,8 @@
#include <net/net_namespace.h>
#include <net/sock.h>

+#define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-"))
+
static LIST_HEAD(nf_tables_expressions);
static LIST_HEAD(nf_tables_objects);
static LIST_HEAD(nf_tables_flowtables);
@@ -504,7 +506,7 @@ static void nft_request_module(struct ne
va_start(args, fmt);
ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
va_end(args);
- if (WARN(ret >= MODULE_NAME_LEN, "truncated: '%s' (len %d)", module_name, ret))
+ if (ret >= MODULE_NAME_LEN)
return;

mutex_unlock(&net->nft.commit_mutex);
@@ -1129,7 +1131,8 @@ static const struct nla_policy nft_chain
.len = NFT_CHAIN_MAXNAMELEN - 1 },
[NFTA_CHAIN_HOOK] = { .type = NLA_NESTED },
[NFTA_CHAIN_POLICY] = { .type = NLA_U32 },
- [NFTA_CHAIN_TYPE] = { .type = NLA_STRING },
+ [NFTA_CHAIN_TYPE] = { .type = NLA_STRING,
+ .len = NFT_MODULE_AUTOLOAD_LIMIT },
[NFTA_CHAIN_COUNTERS] = { .type = NLA_NESTED },
};

@@ -2012,7 +2015,8 @@ static const struct nft_expr_type *nft_e
}

static const struct nla_policy nft_expr_policy[NFTA_EXPR_MAX + 1] = {
- [NFTA_EXPR_NAME] = { .type = NLA_STRING },
+ [NFTA_EXPR_NAME] = { .type = NLA_STRING,
+ .len = NFT_MODULE_AUTOLOAD_LIMIT },
[NFTA_EXPR_DATA] = { .type = NLA_NESTED },
};

@@ -3796,7 +3800,8 @@ static const struct nla_policy nft_set_e
[NFTA_SET_ELEM_USERDATA] = { .type = NLA_BINARY,
.len = NFT_USERDATA_MAXLEN },
[NFTA_SET_ELEM_EXPR] = { .type = NLA_NESTED },
- [NFTA_SET_ELEM_OBJREF] = { .type = NLA_STRING },
+ [NFTA_SET_ELEM_OBJREF] = { .type = NLA_STRING,
+ .len = NFT_OBJ_MAXNAMELEN - 1 },
};

static const struct nla_policy nft_set_elem_list_policy[NFTA_SET_ELEM_LIST_MAX + 1] = {