From 303223092081963513494b4377fa1ac9e362ed4b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 23 Jan 2017 18:21:58 +0100 Subject: [PATCH] netfilter: guarantee 8 byte minalign for template addresses The next change will merge skb->nfct pointer and skb->nfctinfo status bits into single skb->_nfct (unsigned long) area. For this to work nf_conn addresses must always be aligned at least on an 8 byte boundary since we will need the lower 3bits to store nfctinfo. Conntrack templates are allocated via kmalloc. kbuild test robot reported BUILD_BUG_ON failed: NFCT_INFOMASK >= ARCH_KMALLOC_MINALIGN on v1 of this patchset, so not all platforms meet this requirement. Do manual alignment if needed, the alignment offset is stored in the nf_conn entry protocol area. This works because templates are not handed off to L4 protocol trackers. Reported-by: kbuild test robot Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_conntrack.h | 2 ++ net/netfilter/nf_conntrack_core.c | 29 +++++++++++++++++++++++----- 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index d704aed11684..06d3d2d24fe0 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -163,6 +163,8 @@ void nf_conntrack_alter_reply(struct nf_conn *ct, int nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple, const struct nf_conn *ignored_conntrack); +#define NFCT_INFOMASK 7UL + /* Return conntrack_info and tuple hash for given skb. */ static inline struct nf_conn * nf_ct_get(const struct sk_buff *skb, enum ip_conntrack_info *ctinfo) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index c9bd10747864..768968fba7f6 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -350,16 +350,31 @@ static void nf_ct_del_from_dying_or_unconfirmed_list(struct nf_conn *ct) spin_unlock(&pcpu->lock); } +#define NFCT_ALIGN(len) (((len) + NFCT_INFOMASK) & ~NFCT_INFOMASK) + /* Released via destroy_conntrack() */ struct nf_conn *nf_ct_tmpl_alloc(struct net *net, const struct nf_conntrack_zone *zone, gfp_t flags) { - struct nf_conn *tmpl; + struct nf_conn *tmpl, *p; - tmpl = kzalloc(sizeof(*tmpl), flags); - if (tmpl == NULL) - return NULL; + if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK) { + tmpl = kzalloc(sizeof(*tmpl) + NFCT_INFOMASK, flags); + if (!tmpl) + return NULL; + + p = tmpl; + tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p); + if (tmpl != p) { + tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p); + tmpl->proto.tmpl_padto = (char *)tmpl - (char *)p; + } + } else { + tmpl = kzalloc(sizeof(*tmpl), flags); + if (!tmpl) + return NULL; + } tmpl->status = IPS_TEMPLATE; write_pnet(&tmpl->ct_net, net); @@ -374,7 +389,11 @@ void nf_ct_tmpl_free(struct nf_conn *tmpl) { nf_ct_ext_destroy(tmpl); nf_ct_ext_free(tmpl); - kfree(tmpl); + + if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK) + kfree((char *)tmpl - tmpl->proto.tmpl_padto); + else + kfree(tmpl); } EXPORT_SYMBOL_GPL(nf_ct_tmpl_free);