diff options
author | Patrick McHardy <kaber@trash.net> | 2014-04-12 11:17:57 (GMT) |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2014-04-14 08:38:02 (GMT) |
commit | b855d416dc17061ebb271ea7ef1201d100531770 (patch) | |
tree | c021bbfd8d0f1e47675fbe1bbce9889c7f0ecf96 /include | |
parent | ee214d54bf3d51259adf8917e26dc84df1cab05a (diff) | |
download | linux-b855d416dc17061ebb271ea7ef1201d100531770.tar.xz |
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 <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/net/netfilter/nf_tables_core.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h index cf2b7ae..a75fc8e 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); |