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Date: Thu, 17 May 2012 01:26:57 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: Hans Schillstrom <hans.schillstrom@...csson.com>
Cc: kaber@...sh.net, jengelh@...ozas.de,
netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
dan.carpenter@...cle.com, hans@...illstrom.com
Subject: Re: [PATCH] netfilter: xt_HMARK: fix endian bugs and warnings
On Wed, May 16, 2012 at 05:00:42PM +0200, Hans Schillstrom wrote:
> A mix of u32 and __be32 causes endian warning.
> The hash value produced is now the same for big and little endian machines.
> i.e. a mix of Big and Little endian in a cluster is now possible.
>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Hans Schillstrom <hans.schillstrom@...csson.com>
> ---
> include/linux/netfilter/xt_HMARK.h | 5 ++-
> net/netfilter/xt_HMARK.c | 68 ++++++++++++++++++++---------------
> 2 files changed, 42 insertions(+), 31 deletions(-)
>
> diff --git a/include/linux/netfilter/xt_HMARK.h b/include/linux/netfilter/xt_HMARK.h
> index abb1650..8b6307a 100644
> --- a/include/linux/netfilter/xt_HMARK.h
> +++ b/include/linux/netfilter/xt_HMARK.h
> @@ -24,10 +24,11 @@ enum {
>
> union hmark_ports {
> struct {
> - __u16 src;
> - __u16 dst;
> + __be16 src;
> + __be16 dst;
> } p16;
> __u32 v32;
> + __be32 b32;
> };
>
> struct xt_hmark_info {
> diff --git a/net/netfilter/xt_HMARK.c b/net/netfilter/xt_HMARK.c
> index 32fbd73..7bb7b5e 100644
> --- a/net/netfilter/xt_HMARK.c
> +++ b/net/netfilter/xt_HMARK.c
> @@ -32,13 +32,13 @@ MODULE_ALIAS("ipt_HMARK");
> MODULE_ALIAS("ip6t_HMARK");
>
> struct hmark_tuple {
> - u32 src;
> - u32 dst;
> + __be32 src;
> + __be32 dst;
> union hmark_ports uports;
> uint8_t proto;
> };
>
> -static inline u32 hmark_addr6_mask(const __u32 *addr32, const __u32 *mask)
> +static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask)
> {
> return (addr32[0] & mask[0]) ^
> (addr32[1] & mask[1]) ^
> @@ -46,8 +46,8 @@ static inline u32 hmark_addr6_mask(const __u32 *addr32, const __u32 *mask)
> (addr32[3] & mask[3]);
> }
>
> -static inline u32
> -hmark_addr_mask(int l3num, const __u32 *addr32, const __u32 *mask)
> +static inline __be32
> +hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask)
> {
> switch (l3num) {
> case AF_INET:
> @@ -58,6 +58,25 @@ hmark_addr_mask(int l3num, const __u32 *addr32, const __u32 *mask)
> return 0;
> }
>
> +static inline void hmark_port_order(union hmark_ports *uports,
comestical change, better call this hmark_swap_ports
> + const struct xt_hmark_info *info)
> +{
> + union hmark_ports hp;
> +
> + hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
> + hp.v32 = ntohl(hp.b32);
> + /* Make it endian safe into jhash() */
> +#if defined(__LITTLE_ENDIAN)
> + if ((__force u16) uports->p16.dst >
> + (__force u16) uports->p16.src)
> +#else
> + if ((__force u16) uports->p16.src >
> + (__force u16) uports->p16.dst)
> +#endif
This ifdef is ugly. I prefer if you use ntohs the ports and store
the values in some local variable, then compare and swap if required.
Just like you do with the IPv4 address.
> + swap(hp.p16.src, hp.p16.dst);
> + uports->v32 = hp.v32;
> +}
> +
> static int
> hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
> const struct xt_hmark_info *info)
> @@ -74,10 +93,10 @@ hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
> otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
> rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
>
> - t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.all,
> - info->src_mask.all);
> - t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.all,
> - info->dst_mask.all);
> + t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.ip6,
> + info->src_mask.ip6);
> + t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6,
> + info->dst_mask.ip6);
>
> if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
> return 0;
> @@ -86,10 +105,7 @@ hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
> if (t->proto != IPPROTO_ICMP) {
> t->uports.p16.src = otuple->src.u.all;
> t->uports.p16.dst = rtuple->src.u.all;
> - t->uports.v32 = (t->uports.v32 & info->port_mask.v32) |
> - info->port_set.v32;
> - if (t->uports.p16.dst < t->uports.p16.src)
> - swap(t->uports.p16.dst, t->uports.p16.src);
> + hmark_port_order(&t->uports, info);
> }
>
> return 0;
> @@ -102,11 +118,13 @@ static inline u32
> hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
> {
> u32 hash;
> + u32 src = ntohl(t->src);
> + u32 dst = ntohl(t->dst);
>
> - if (t->dst < t->src)
> - swap(t->src, t->dst);
> + if (dst < src)
> + swap(src, dst);
>
> - hash = jhash_3words(t->src, t->dst, t->uports.v32, info->hashrnd);
> + hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
> hash = hash ^ (t->proto & info->proto_mask);
>
> return (((u64)hash * info->hmodulus) >> 32) + info->hoffset;
> @@ -125,12 +143,7 @@ hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
> nhoff += protoff;
> if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0)
> return;
> -
> - t->uports.v32 = (t->uports.v32 & info->port_mask.v32) |
> - info->port_set.v32;
> -
> - if (t->uports.p16.dst < t->uports.p16.src)
> - swap(t->uports.p16.dst, t->uports.p16.src);
> + hmark_port_order(&t->uports, info);
> }
>
> #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
> @@ -178,8 +191,8 @@ hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t,
> return -1;
> }
> noicmp:
> - t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.all);
> - t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.all);
> + t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.ip6);
> + t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6);
>
> if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
> return 0;
> @@ -255,11 +268,8 @@ hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t,
> }
> }
>
> - t->src = (__force u32) ip->saddr;
> - t->dst = (__force u32) ip->daddr;
> -
> - t->src &= info->src_mask.ip;
> - t->dst &= info->dst_mask.ip;
> + t->src = ip->saddr & info->src_mask.ip;
> + t->dst = ip->daddr & info->dst_mask.ip;
>
> if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
> return 0;
> --
> 1.7.2.3
>
> --
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