netfilter: nf_tables: fix mismatch in big-endian system

Currently, there are two different methods to store an u16 integer to
the u32 data register. For example:
  u32 *dest = &regs->data[priv->dreg];
  1. *dest = 0; *(u16 *) dest = val_u16;
  2. *dest = val_u16;

For method 1, the u16 value will be stored like this, either in
big-endian or little-endian system:
  0          15           31
  +-+-+-+-+-+-+-+-+-+-+-+-+
  |   Value   |     0     |
  +-+-+-+-+-+-+-+-+-+-+-+-+

For method 2, in little-endian system, the u16 value will be the same
as listed above. But in big-endian system, the u16 value will be stored
like this:
  0          15           31
  +-+-+-+-+-+-+-+-+-+-+-+-+
  |     0     |   Value   |
  +-+-+-+-+-+-+-+-+-+-+-+-+

So later we use "memcmp(&regs->data[priv->sreg], data, 2);" to do
compare in nft_cmp, nft_lookup expr ..., method 2 will get the wrong
result in big-endian system, as 0~15 bits will always be zero.

For the similar reason, when loading an u16 value from the u32 data
register, we should use "*(u16 *) sreg;" instead of "(u16)*sreg;",
the 2nd method will get the wrong value in the big-endian system.

So introduce some wrapper functions to store/load an u8 or u16
integer to/from the u32 data register, and use them in the right
place.

Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

7 files changed, 51 insertions, 47 deletions

diff --git a/net/ipv4/netfilter/nft_masq_ipv4.c b/net/ipv4/netfilter/nft_masq_ipv4.c
index a0ea8aad1bf1..f18677277119 100644
--- a/net/ipv4/netfilter/nft_masq_ipv4.c
+++ b/net/ipv4/netfilter/nft_masq_ipv4.c
@@ -26,10 +26,10 @@ static void nft_masq_ipv4_eval(const struct nft_expr *expr,
         memset(&range, 0, sizeof(range));
         range.flags = priv->flags;
         if (priv->sreg_proto_min) {
-                range.min_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_min];
-                range.max_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_max];
+                range.min_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_min]);
+                range.max_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_max]);
         }
         regs->verdict.code = nf_nat_masquerade_ipv4(pkt->skb, nft_hook(pkt),
                                                     &range, nft_out(pkt));
diff --git a/net/ipv4/netfilter/nft_redir_ipv4.c b/net/ipv4/netfilter/nft_redir_ipv4.c
index 1650ed23c15d..5120be1d3118 100644
--- a/net/ipv4/netfilter/nft_redir_ipv4.c
+++ b/net/ipv4/netfilter/nft_redir_ipv4.c
@@ -26,10 +26,10 @@ static void nft_redir_ipv4_eval(const struct nft_expr *expr,
 
         memset(&mr, 0, sizeof(mr));
         if (priv->sreg_proto_min) {
-                mr.range[0].min.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_min];
-                mr.range[0].max.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_max];
+                mr.range[0].min.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_min]);
+                mr.range[0].max.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_max]);
                 mr.range[0].flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
         }
 
diff --git a/net/ipv6/netfilter/nft_masq_ipv6.c b/net/ipv6/netfilter/nft_masq_ipv6.c
index 6c5b5b1830a7..4146536e9c15 100644
--- a/net/ipv6/netfilter/nft_masq_ipv6.c
+++ b/net/ipv6/netfilter/nft_masq_ipv6.c
@@ -27,10 +27,10 @@ static void nft_masq_ipv6_eval(const struct nft_expr *expr,
         memset(&range, 0, sizeof(range));
         range.flags = priv->flags;
         if (priv->sreg_proto_min) {
-                range.min_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_min];
-                range.max_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_max];
+                range.min_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_min]);
+                range.max_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_max]);
         }
         regs->verdict.code = nf_nat_masquerade_ipv6(pkt->skb, &range,
                                                     nft_out(pkt));
diff --git a/net/ipv6/netfilter/nft_redir_ipv6.c b/net/ipv6/netfilter/nft_redir_ipv6.c
index f5ac080fc084..a27e424f690d 100644
--- a/net/ipv6/netfilter/nft_redir_ipv6.c
+++ b/net/ipv6/netfilter/nft_redir_ipv6.c
@@ -26,10 +26,10 @@ static void nft_redir_ipv6_eval(const struct nft_expr *expr,
 
         memset(&range, 0, sizeof(range));
         if (priv->sreg_proto_min) {
-                range.min_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_min],
-                range.max_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_max],
+                range.min_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_min]);
+                range.max_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_max]);
                 range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
         }
 
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index bf548a7a71ec..91585b5e5307 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -83,7 +83,7 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
 
         switch (priv->key) {
         case NFT_CT_DIRECTION:
-                *dest = CTINFO2DIR(ctinfo);
+                nft_reg_store8(dest, CTINFO2DIR(ctinfo));
                 return;
         case NFT_CT_STATUS:
                 *dest = ct->status;
@@ -151,20 +151,22 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
                 return;
         }
         case NFT_CT_L3PROTOCOL:
-                *dest = nf_ct_l3num(ct);
+                nft_reg_store8(dest, nf_ct_l3num(ct));
                 return;
         case NFT_CT_PROTOCOL:
-                *dest = nf_ct_protonum(ct);
+                nft_reg_store8(dest, nf_ct_protonum(ct));
                 return;
 #ifdef CONFIG_NF_CONNTRACK_ZONES
         case NFT_CT_ZONE: {
                 const struct nf_conntrack_zone *zone = nf_ct_zone(ct);
+                u16 zoneid;
 
                 if (priv->dir < IP_CT_DIR_MAX)
-                        *dest = nf_ct_zone_id(zone, priv->dir);
+                        zoneid = nf_ct_zone_id(zone, priv->dir);
                 else
-                        *dest = zone->id;
+                        zoneid = zone->id;
 
+                nft_reg_store16(dest, zoneid);
                 return;
         }
 #endif
@@ -183,10 +185,10 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
                        nf_ct_l3num(ct) == NFPROTO_IPV4 ? 4 : 16);
                 return;
         case NFT_CT_PROTO_SRC:
-                *dest = (__force __u16)tuple->src.u.all;
+                nft_reg_store16(dest, (__force u16)tuple->src.u.all);
                 return;
         case NFT_CT_PROTO_DST:
-                *dest = (__force __u16)tuple->dst.u.all;
+                nft_reg_store16(dest, (__force u16)tuple->dst.u.all);
                 return;
         default:
                 break;
@@ -205,7 +207,7 @@ static void nft_ct_set_zone_eval(const struct nft_expr *expr,
         const struct nft_ct *priv = nft_expr_priv(expr);
         struct sk_buff *skb = pkt->skb;
         enum ip_conntrack_info ctinfo;
-        u16 value = regs->data[priv->sreg];
+        u16 value = nft_reg_load16(&regs->data[priv->sreg]);
         struct nf_conn *ct;
 
         ct = nf_ct_get(skb, &ctinfo);
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index e1f5ca9b423b..7b60e01f38ff 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -45,16 +45,15 @@ void nft_meta_get_eval(const struct nft_expr *expr,
                 *dest = skb->len;
                 break;
         case NFT_META_PROTOCOL:
-                *dest = 0;
-                *(__be16 *)dest = skb->protocol;
+                nft_reg_store16(dest, (__force u16)skb->protocol);
                 break;
         case NFT_META_NFPROTO:
-                *dest = nft_pf(pkt);
+                nft_reg_store8(dest, nft_pf(pkt));
                 break;
         case NFT_META_L4PROTO:
                 if (!pkt->tprot_set)
                         goto err;
-                *dest = pkt->tprot;
+                nft_reg_store8(dest, pkt->tprot);
                 break;
         case NFT_META_PRIORITY:
                 *dest = skb->priority;
@@ -85,14 +84,12 @@ void nft_meta_get_eval(const struct nft_expr *expr,
         case NFT_META_IIFTYPE:
                 if (in == NULL)
                         goto err;
-                *dest = 0;
-                *(u16 *)dest = in->type;
+                nft_reg_store16(dest, in->type);
                 break;
         case NFT_META_OIFTYPE:
                 if (out == NULL)
                         goto err;
-                *dest = 0;
-                *(u16 *)dest = out->type;
+                nft_reg_store16(dest, out->type);
                 break;
         case NFT_META_SKUID:
                 sk = skb_to_full_sk(skb);
@@ -142,19 +139,19 @@ void nft_meta_get_eval(const struct nft_expr *expr,
 #endif
         case NFT_META_PKTTYPE:
                 if (skb->pkt_type != PACKET_LOOPBACK) {
-                        *dest = skb->pkt_type;
+                        nft_reg_store8(dest, skb->pkt_type);
                         break;
                 }
 
                 switch (nft_pf(pkt)) {
                 case NFPROTO_IPV4:
                         if (ipv4_is_multicast(ip_hdr(skb)->daddr))
-                                *dest = PACKET_MULTICAST;
+                                nft_reg_store8(dest, PACKET_MULTICAST);
                         else
-                                *dest = PACKET_BROADCAST;
+                                nft_reg_store8(dest, PACKET_BROADCAST);
                         break;
                 case NFPROTO_IPV6:
-                        *dest = PACKET_MULTICAST;
+                        nft_reg_store8(dest, PACKET_MULTICAST);
                         break;
                 case NFPROTO_NETDEV:
                         switch (skb->protocol) {
@@ -168,14 +165,14 @@ void nft_meta_get_eval(const struct nft_expr *expr,
                                         goto err;
 
                                 if (ipv4_is_multicast(iph->daddr))
-                                        *dest = PACKET_MULTICAST;
+                                        nft_reg_store8(dest, PACKET_MULTICAST);
                                 else
-                                        *dest = PACKET_BROADCAST;
+                                        nft_reg_store8(dest, PACKET_BROADCAST);
 
                                 break;
                         }
                         case htons(ETH_P_IPV6):
-                                *dest = PACKET_MULTICAST;
+                                nft_reg_store8(dest, PACKET_MULTICAST);
                                 break;
                         default:
                                 WARN_ON_ONCE(1);
@@ -230,7 +227,9 @@ void nft_meta_set_eval(const struct nft_expr *expr,
 {
         const struct nft_meta *meta = nft_expr_priv(expr);
         struct sk_buff *skb = pkt->skb;
-        u32 value = regs->data[meta->sreg];
+        u32 *sreg = &regs->data[meta->sreg];
+        u32 value = *sreg;
+        u8 pkt_type;
 
         switch (meta->key) {
         case NFT_META_MARK:
@@ -240,9 +239,12 @@ void nft_meta_set_eval(const struct nft_expr *expr,
                 skb->priority = value;
                 break;
         case NFT_META_PKTTYPE:
-                if (skb->pkt_type != value &&
-                    skb_pkt_type_ok(value) && skb_pkt_type_ok(skb->pkt_type))
-                        skb->pkt_type = value;
+                pkt_type = nft_reg_load8(sreg);
+
+                if (skb->pkt_type != pkt_type &&
+                    skb_pkt_type_ok(pkt_type) &&
+                    skb_pkt_type_ok(skb->pkt_type))
+                        skb->pkt_type = pkt_type;
                 break;
         case NFT_META_NFTRACE:
                 skb->nf_trace = !!value;
diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index 19a7bf3236f9..439e0bd152a0 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -65,10 +65,10 @@ static void nft_nat_eval(const struct nft_expr *expr,
         }
 
         if (priv->sreg_proto_min) {
-                range.min_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_min];
-                range.max_proto.all =
-                        *(__be16 *)&regs->data[priv->sreg_proto_max];
+                range.min_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_min]);
+                range.max_proto.all = (__force __be16)nft_reg_load16(
+                        &regs->data[priv->sreg_proto_max]);
                 range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
         }