From dcf67740f22d31be685d7172f05b289c8243ea12 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 16 Apr 2017 01:29:15 +0200 Subject: netfilter: helper: add build-time asserts for helper data size add a 32 byte scratch area in the helper struct instead of relying on variable sized helpers plus compile-time asserts to let us know if 32 bytes aren't enough anymore. Not having variable sized helpers will later allow to add BUILD_BUG_ON for the total size of conntrack extensions -- the helper extension is the only one that doesn't have a fixed size. The (useless!) NF_CT_HELPER_BUILD_BUG_ON(0); are added so that in case someone adds a new helper and copy-pastes from one that doesn't store private data at least some indication that this macro should be used somehow is there... Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack_helper.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/net') diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h index 15d746558665..29539ed1008f 100644 --- a/include/net/netfilter/nf_conntrack_helper.h +++ b/include/net/netfilter/nf_conntrack_helper.h @@ -66,9 +66,12 @@ struct nf_conn_help { u8 expecting[NF_CT_MAX_EXPECT_CLASSES]; /* private helper information. */ - char data[]; + char data[32] __aligned(8); }; +#define NF_CT_HELPER_BUILD_BUG_ON(structsize) \ + BUILD_BUG_ON((structsize) > FIELD_SIZEOF(struct nf_conn_help, data)) + struct nf_conntrack_helper *__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum); -- cgit v1.2.1