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netfilter: nf_tables: fix mismatch in big-endian system

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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 <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
This commit is contained in:
Liping Zhang 2017-03-08 22:54:18 +08:00 • committed by Pablo Neira Ayuso
commit 10596608c4
8 changed files with 80 additions and 47 deletions
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8
net/ipv6/netfilter/nft_masq_ipv6.c
View file

@ -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));

8
net/ipv6/netfilter/nft_redir_ipv6.c
View file

@ -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;
}