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net: filter: constify detection of pkt_type_offset

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Currently we have 2 pkt_type_offset functions doing the same thing and
spread across the architecture files. Remove those and replace them
with a PKT_TYPE_OFFSET macro helper which gets the constant value from a
zero sized sk_buff member right in front of the bitfield with offsetof.
This new offset marker does not change size of struct sk_buff.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hannes Frederic Sowa
2014-09-12 14:04:43 +02:00
committed by David S. Miller
parent ac7a04c33d
commit 233577a220
4 changed files with 14 additions and 89 deletions
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31
net/core/filter.c
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@@ -87,30 +87,6 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
}
EXPORT_SYMBOL(sk_filter);
/* Helper to find the offset of pkt_type in sk_buff structure. We want
* to make sure its still a 3bit field starting at a byte boundary;
* taken from arch/x86/net/bpf_jit_comp.c.
*/
#ifdef __BIG_ENDIAN_BITFIELD
#define PKT_TYPE_MAX (7 << 5)
#else
#define PKT_TYPE_MAX 7
#endif
static unsigned int pkt_type_offset(void)
{
struct sk_buff skb_probe = { .pkt_type = ~0, };
u8 *ct = (u8 *) &skb_probe;
unsigned int off;
for (off = 0; off < sizeof(struct sk_buff); off++) {
if (ct[off] == PKT_TYPE_MAX)
return off;
}
pr_err_once("Please fix %s, as pkt_type couldn't be found!\n", __func__);
return -1;
}
static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
{
return skb_get_poff((struct sk_buff *)(unsigned long) ctx);
@@ -190,11 +166,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
break;
case SKF_AD_OFF + SKF_AD_PKTTYPE:
*insn = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX,
pkt_type_offset());
if (insn->off < 0)
return false;
insn++;
*insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX,
PKT_TYPE_OFFSET());
*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX);
#ifdef __BIG_ENDIAN_BITFIELD
insn++;