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netfilter: guarantee 8 byte minalign for template addresses

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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 <fengguang.wu@intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2017-01-23 18:21:58 +01:00 committed by Pablo Neira Ayuso
parent c74454fadd
commit 3032230920
2 changed files with 26 additions and 5 deletions
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2
include/net/netfilter/nf_conntrack.h
View File

@ -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)

29
net/netfilter/nf_conntrack_core.c
View File

@ -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);