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net: filter: fix SKF_AD_PKTTYPE extension on big-endian

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BPF classic->internal converter broke SKF_AD_PKTTYPE extension, since
pkt_type_offset() was failing to find skb->pkt_type field which is defined as:
__u8 pkt_type:3,
     fclone:2,
     ipvs_property:1,
     peeked:1,
     nf_trace:1;

Fix it by searching for 3 most significant bits and shift them by 5 at run-time

Fixes: bd4cf0ed33 ("net: filter: rework/optimize internal BPF interpreter's instruction set")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-06-05 14:39:36 -07:00 committed by David S. Miller
parent 78c8dbb652
commit 0dcceabb0c
1 changed files with 11 additions and 0 deletions
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11
net/core/filter.c
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@ -578,7 +578,11 @@ EXPORT_SYMBOL_GPL(sk_run_filter_int_skb);
* 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, };
@ -685,6 +689,13 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
insn->code = BPF_ALU | BPF_AND | BPF_K;
insn->a_reg = A_REG;
insn->imm = PKT_TYPE_MAX;
#ifdef __BIG_ENDIAN_BITFIELD
insn++;
insn->code = BPF_ALU | BPF_RSH | BPF_K;
insn->a_reg = A_REG;
insn->imm = 5;
#endif
break;
case SKF_AD_OFF + SKF_AD_IFINDEX: