From b855d416dc17061ebb271ea7ef1201d100531770 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Sat, 12 Apr 2014 13:17:57 +0200 Subject: netfilter: nf_tables: fix nft_cmp_fast failure on big endian for size < 4 nft_cmp_fast is used for equality comparisions of size <= 4. For comparisions of size < 4 byte a mask is calculated that is applied to both the data from userspace (during initialization) and the register value (during runtime). Both values are stored using (in effect) memcpy to a memory area that is then interpreted as u32 by nft_cmp_fast. This works fine on little endian since smaller types have the same base address, however on big endian this is not true and the smaller types are interpreted as a big number with trailing zero bytes. The mask therefore must not include the lower bytes, but the higher bytes on big endian. Add a helper function that does a cpu_to_le32 to switch the bytes on big endian. Since we're dealing with a mask of just consequitive bits, this works out fine. Signed-off-by: Patrick McHardy Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables_core.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include') diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h index cf2b7ae2b9d8..a75fc8e27cd6 100644 --- a/include/net/netfilter/nf_tables_core.h +++ b/include/net/netfilter/nf_tables_core.h @@ -13,6 +13,16 @@ struct nft_cmp_fast_expr { u8 len; }; +/* Calculate the mask for the nft_cmp_fast expression. On big endian the + * mask needs to include the *upper* bytes when interpreting that data as + * something smaller than the full u32, therefore a cpu_to_le32 is done. + */ +static inline u32 nft_cmp_fast_mask(unsigned int len) +{ + return cpu_to_le32(~0U >> (FIELD_SIZEOF(struct nft_cmp_fast_expr, + data) * BITS_PER_BYTE - len)); +} + extern const struct nft_expr_ops nft_cmp_fast_ops; int nft_cmp_module_init(void); -- cgit