Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b4fe0ec8 authored by Markos Chandras's avatar Markos Chandras Committed by Ralf Baechle
Browse files

MIPS: bpf: Fix PKT_TYPE case for big-endian cores 



The skb->pkt_type field is defined as follows:

u8 pkt_type:3,
   fclone:2,
   ipvs_property:1,
   peeked:1,
   nf_trace:1

resulting to the following layout in big-endian systems

[pkt_type][fclone][ipvs_propery][peeked][nf_trace]
^                                                ^
|                                                |
LSB                                             MSB

As a result, the existing code did not work because it was trying to
match pkt_type == 7 whereas in reality it is 7<<5 on big-endian
systems.

This has been fixed in the interpreter in
0dcceabb
"net: filter: fix SKF_AD_PKTTYPE extension on big-endian"

The fix is to look for 7<<5 on big-endian systems for the pkt_type
field, and shift by 5 so the packet type will be at the lower 3 bits
of the A register.

Signed-off-by: default avatarMarkos Chandras <markos.chandras@imgtec.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: netdev@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7132/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 95782bf4

arch/mips/net/bpf_jit.c

+10 −2
Original line number Original line Diff line number Diff line
@@ -751,13 +751,17 @@ static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset) 
	return (u64)err << 32 | ntohl(ret);

	return (u64)err << 32 | ntohl(ret);

}

}





#ifdef __BIG_ENDIAN_BITFIELD

#define PKT_TYPE_MAX	(7 << 5)

#else

#define PKT_TYPE_MAX	7

#define PKT_TYPE_MAX	7

#endif

static int pkt_type_offset(void)

static int pkt_type_offset(void)

{

{

	struct sk_buff skb_probe = {

	struct sk_buff skb_probe = {

		.pkt_type = ~0,

		.pkt_type = ~0,

	};

	};

	char *ct = (char *)&skb_probe;

	u8 *ct = (u8 *)&skb_probe;

	unsigned int off;

	unsigned int off;





	for (off = 0; off < sizeof(struct sk_buff); off++) {

	for (off = 0; off < sizeof(struct sk_buff); off++) {
@@ -1320,6 +1324,10 @@ static int build_body(struct jit_ctx *ctx) 
			emit_load_byte(r_tmp, r_skb, off, ctx);

			emit_load_byte(r_tmp, r_skb, off, ctx);

			/* Keep only the last 3 bits */

			/* Keep only the last 3 bits */

			emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx);

			emit_andi(r_A, r_tmp, PKT_TYPE_MAX, ctx);

#ifdef __BIG_ENDIAN_BITFIELD

			/* Get the actual packet type to the lower 3 bits */

			emit_srl(r_A, r_A, 5, ctx);

#endif

			break;

			break;

		case BPF_ANC | SKF_AD_QUEUE:

		case BPF_ANC | SKF_AD_QUEUE:

			ctx->flags |= SEEN_SKB | SEEN_A;

			ctx->flags |= SEEN_SKB | SEEN_A;