netfilter: xt_nfacct: Fix alignment mismatch in xt_nfacct_match_info

When running a 64-bit kernel with a 32-bit iptables binary, the size of
the xt_nfacct_match_info struct diverges.

    kernel: sizeof(struct xt_nfacct_match_info) : 40
    iptables: sizeof(struct xt_nfacct_match_info)) : 36

Trying to append nfacct related rules results in an unhelpful message.
Although it is suggested to look for more information in dmesg, nothing
can be found there.

    # iptables -A <chain> -m nfacct --nfacct-name <acct-object>
    iptables: Invalid argument. Run `dmesg' for more information.

This patch fixes the memory misalignment by enforcing 8-byte alignment
within the struct's first revision. This solution is often used in many
other uapi netfilter headers.

Signed-off-by: Juliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/uapi/linux/netfilter/xt_nfacct.h b/include/uapi/linux/netfilter/xt_nfacct.h
index 5c8a4d7..b5123ab 100644 (file)
--- a/include/uapi/linux/netfilter/xt_nfacct.h
+++ b/include/uapi/linux/netfilter/xt_nfacct.h
@@ -11,4 +11,9 @@ struct xt_nfacct_match_info {
        struct nf_acct  *nfacct;
 };
 
+struct xt_nfacct_match_info_v1 {
+       char            name[NFACCT_NAME_MAX];
+       struct nf_acct  *nfacct __attribute__((aligned(8)));
+};
+
 #endif /* _XT_NFACCT_MATCH_H */

diff --git a/net/netfilter/xt_nfacct.c b/net/netfilter/xt_nfacct.c
index d0ab1ad..5aab6df 100644 (file)
--- a/net/netfilter/xt_nfacct.c
+++ b/net/netfilter/xt_nfacct.c
@@ -54,25 +54,39 @@ nfacct_mt_destroy(const struct xt_mtdtor_param *par)
        nfnl_acct_put(info->nfacct);
 }
 
-static struct xt_match nfacct_mt_reg __read_mostly = {
-       .name       = "nfacct",
-       .family     = NFPROTO_UNSPEC,
-       .checkentry = nfacct_mt_checkentry,
-       .match      = nfacct_mt,
-       .destroy    = nfacct_mt_destroy,
-       .matchsize  = sizeof(struct xt_nfacct_match_info),
-       .usersize   = offsetof(struct xt_nfacct_match_info, nfacct),
-       .me         = THIS_MODULE,
+static struct xt_match nfacct_mt_reg[] __read_mostly = {
+       {
+               .name       = "nfacct",
+               .revision   = 0,
+               .family     = NFPROTO_UNSPEC,
+               .checkentry = nfacct_mt_checkentry,
+               .match      = nfacct_mt,
+               .destroy    = nfacct_mt_destroy,
+               .matchsize  = sizeof(struct xt_nfacct_match_info),
+               .usersize   = offsetof(struct xt_nfacct_match_info, nfacct),
+               .me         = THIS_MODULE,
+       },
+       {
+               .name       = "nfacct",
+               .revision   = 1,
+               .family     = NFPROTO_UNSPEC,
+               .checkentry = nfacct_mt_checkentry,
+               .match      = nfacct_mt,
+               .destroy    = nfacct_mt_destroy,
+               .matchsize  = sizeof(struct xt_nfacct_match_info_v1),
+               .usersize   = offsetof(struct xt_nfacct_match_info_v1, nfacct),
+               .me         = THIS_MODULE,
+       },
 };
 
 static int __init nfacct_mt_init(void)
 {
-       return xt_register_match(&nfacct_mt_reg);
+       return xt_register_matches(nfacct_mt_reg, ARRAY_SIZE(nfacct_mt_reg));
 }
 
 static void __exit nfacct_mt_exit(void)
 {
-       xt_unregister_match(&nfacct_mt_reg);
+       xt_unregister_matches(nfacct_mt_reg, ARRAY_SIZE(nfacct_mt_reg));
 }
 
 module_init(nfacct_mt_init);