From b3a5db109e0670d6d168e9cd9de4d272a68f7c35 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 16 Apr 2017 01:29:19 +0200 Subject: [PATCH] netfilter: conntrack: use u8 for extension sizes again commit 223b02d923ecd7c84cf9780bb3686f455d279279 ("netfilter: nf_conntrack: reserve two bytes for nf_ct_ext->len") had to increase size of the extension offsets because total size of the extensions had increased to a point where u8 did overflow. 3 years later we've managed to diet extensions a bit and we no longer need u16. Furthermore we can now add a compile-time assertion for this problem. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack_extend.h | 4 +-- net/netfilter/nf_conntrack_core.c | 33 +++++++++++++++++++++ 2 files changed, 35 insertions(+), 2 deletions(-) diff --git a/include/net/netfilter/nf_conntrack_extend.h b/include/net/netfilter/nf_conntrack_extend.h index 4ec645c8b647..5fc908dc9f32 100644 --- a/include/net/netfilter/nf_conntrack_extend.h +++ b/include/net/netfilter/nf_conntrack_extend.h @@ -43,8 +43,8 @@ enum nf_ct_ext_id { /* Extensions: optional stuff which isn't permanently in struct. */ struct nf_ct_ext { struct rcu_head rcu; - u16 offset[NF_CT_EXT_NUM]; - u16 len; + u8 offset[NF_CT_EXT_NUM]; + u8 len; char data[0]; }; diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 03150f60714d..62368b05cef5 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1804,12 +1804,45 @@ EXPORT_SYMBOL_GPL(nf_conntrack_set_hashsize); module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint, &nf_conntrack_htable_size, 0600); +static unsigned int total_extension_size(void) +{ + /* remember to add new extensions below */ + BUILD_BUG_ON(NF_CT_EXT_NUM > 9); + + return sizeof(struct nf_ct_ext) + + sizeof(struct nf_conn_help) +#if IS_ENABLED(CONFIG_NF_NAT) + + sizeof(struct nf_conn_nat) +#endif + + sizeof(struct nf_conn_seqadj) + + sizeof(struct nf_conn_acct) +#ifdef CONFIG_NF_CONNTRACK_EVENTS + + sizeof(struct nf_conntrack_ecache) +#endif +#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP + + sizeof(struct nf_conn_tstamp) +#endif +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + + sizeof(struct nf_conn_timeout) +#endif +#ifdef CONFIG_NF_CONNTRACK_LABELS + + sizeof(struct nf_conn_labels) +#endif +#if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY) + + sizeof(struct nf_conn_synproxy) +#endif + ; +}; + int nf_conntrack_init_start(void) { int max_factor = 8; int ret = -ENOMEM; int i; + /* struct nf_ct_ext uses u8 to store offsets/size */ + BUILD_BUG_ON(total_extension_size() > 255u); + seqcount_init(&nf_conntrack_generation); for (i = 0; i < CONNTRACK_LOCKS; i++) -- 2.20.1