From: Florian Westphal <fw@xxxxxxxxx>
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 <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
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++)
--
2.1.4
--
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