From 10596608c4d62cb8c1c2b806debcbd32fe657e71 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Wed, 8 Mar 2017 22:54:18 +0800 Subject: 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 = ®s->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(®s->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 Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/nf_tables.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'include/net/netfilter') diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 2aa8a9d..70c5ca0 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -103,6 +103,35 @@ 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) { -- cgit v1.1