netfilter: xt_HMARK: fix endianness and provide consistent hashing

This patch addresses two issues:

a) Fix usage of u32 and __be32 that causes endianess warnings via sparse.
b) Ensure consistent hashing in a cluster that is composed of big and
   little endian systems. Thus, we obtain the same hash mark in an
   heterogeneous cluster.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 46 insertions, 31 deletions

diff --git a/include/linux/netfilter/xt_HMARK.h b/include/linux/netfilter/xt_HMARK.h
index abb1650940d2..826fc5807577 100644
--- a/include/linux/netfilter/xt_HMARK.h
+++ b/include/linux/netfilter/xt_HMARK.h
@@ -27,7 +27,12 @@ union hmark_ports {
                 __u16   src;
                 __u16   dst;
         } p16;
+        struct {
+                __be16  src;
+                __be16  dst;
+        } b16;
         __u32   v32;
+        __be32  b32;
 };
 
 struct xt_hmark_info {
diff --git a/net/netfilter/xt_HMARK.c b/net/netfilter/xt_HMARK.c
index 0a96a43108ed..1686ca1b53a1 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;
+        u8                      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 +58,22 @@ hmark_addr_mask(int l3num, const __u32 *addr32, const __u32 *mask)
         return 0;
 }
 
+static inline void hmark_swap_ports(union hmark_ports *uports,
+                                    const struct xt_hmark_info *info)
+{
+        union hmark_ports hp;
+        u16 src, dst;
+
+        hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
+        src = ntohs(hp.b16.src);
+        dst = ntohs(hp.b16.dst);
+
+        if (dst > src)
+                uports->v32 = (dst << 16) | src;
+        else
+                uports->v32 = (src << 16) | dst;
+}
+
 static int
 hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
                     const struct xt_hmark_info *info)
@@ -74,22 +90,19 @@ 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;
 
         t->proto = nf_ct_protonum(ct);
         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);
+                t->uports.b16.src = otuple->src.u.all;
+                t->uports.b16.dst = rtuple->src.u.all;
+                hmark_swap_ports(&t->uports, info);
         }
 
         return 0;
@@ -98,15 +111,19 @@ hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
 #endif
 }
 
+/* This hash function is endian independent, to ensure consistent hashing if
+ * the cluster is composed of big and little endian systems. */
 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;
@@ -126,11 +143,7 @@ hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
         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_swap_ports(&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;