[PATCH 4.9 56/58] netfilter: nf_tables: fix mismatch in big-endian system

From: Greg Kroah-Hartman
Date: Mon Feb 18 2019 - 09:29:03 EST

4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Liping Zhang <zlpnobody@xxxxxxxxx>

commit 10596608c4d62cb8c1c2b806debcbd32fe657e71 upstream.

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@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/net/netfilter/nf_tables.h | 29 ++++++++++++++++++++++++
net/ipv4/netfilter/nft_masq_ipv4.c | 8 +++---
net/ipv4/netfilter/nft_redir_ipv4.c | 8 +++---
net/ipv6/netfilter/nft_masq_ipv6.c | 8 +++---
net/ipv6/netfilter/nft_redir_ipv6.c | 8 +++---
net/netfilter/nft_ct.c | 10 ++++----
net/netfilter/nft_meta.c | 42 ++++++++++++++++++------------------
net/netfilter/nft_nat.c | 8 +++---
8 files changed, 76 insertions(+), 45 deletions(-)

--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -87,6 +87,35 @@ struct nft_regs {
};
};

+/* Store/load an u16 or u8 integer to/from the u32 data register.
+ *
+ * Note, when using concatenations, register allocation happens at 32-bit
+ * level. So for store instruction, pad the rest part with zero to avoid
+ * garbage values.
+ */
+
+static inline void nft_reg_store16(u32 *dreg, u16 val)
+{
+ *dreg = 0;
+ *(u16 *)dreg = val;
+}
+
+static inline void nft_reg_store8(u32 *dreg, u8 val)
+{
+ *dreg = 0;
+ *(u8 *)dreg = val;
+}
+
+static inline u16 nft_reg_load16(u32 *sreg)
+{
+ return *(u16 *)sreg;
+}
+
+static inline u8 nft_reg_load8(u32 *sreg)
+{
+ return *(u8 *)sreg;
+}
+
static inline void nft_data_copy(u32 *dst, const struct nft_data *src,
unsigned int len)
{
--- 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 str
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, pkt->hook,
&range, pkt->out);
--- 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 st

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;
}

--- 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 str
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, pkt->out);
}
--- 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 st

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;
}

--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -77,7 +77,7 @@ static void nft_ct_get_eval(const struct

switch (priv->key) {
case NFT_CT_DIRECTION:
- *dest = CTINFO2DIR(ctinfo);
+ nft_reg_store8(dest, CTINFO2DIR(ctinfo));
return;
case NFT_CT_STATUS:
*dest = ct->status;
@@ -129,10 +129,10 @@ static void nft_ct_get_eval(const struct
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;
default:
break;
@@ -149,10 +149,10 @@ static void nft_ct_get_eval(const struct
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;
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -45,16 +45,15 @@ void nft_meta_get_eval(const struct nft_
*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 = pkt->pf;
+ nft_reg_store8(dest, pkt->pf);
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_
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);
@@ -142,22 +139,22 @@ void nft_meta_get_eval(const struct nft_
#endif
case NFT_META_PKTTYPE:
if (skb->pkt_type != PACKET_LOOPBACK) {
- *dest = skb->pkt_type;
+ nft_reg_store8(dest, skb->pkt_type);
break;
}

switch (pkt->pf) {
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:
if (ipv6_hdr(skb)->daddr.s6_addr[0] == 0xFF)
- *dest = PACKET_MULTICAST;
+ nft_reg_store8(dest, PACKET_MULTICAST);
else
- *dest = PACKET_BROADCAST;
+ nft_reg_store8(dest, PACKET_BROADCAST);
break;
case NFPROTO_NETDEV:
switch (skb->protocol) {
@@ -171,14 +168,14 @@ void nft_meta_get_eval(const struct nft_
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);
@@ -233,7 +230,9 @@ void nft_meta_set_eval(const struct nft_
{
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:
@@ -243,9 +242,12 @@ void nft_meta_set_eval(const struct nft_
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;
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -65,10 +65,10 @@ static void nft_nat_eval(const struct nf
}

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;
}