Commit 0dcceabb authored Jun 05, 2014 by Alexei Starovoitov Committed by David S. Miller Jun 05, 2014

net: filter: fix SKF_AD_PKTTYPE extension on big-endian



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: bd4cf0ed ("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>

parent 78c8dbb6

net/core/filter.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -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: