Commit 9bb05349 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Andrii Nakryiko
Browse files

bpf: Add hwtstamp field for the sockops prog 



The bpf-tc prog has already been able to access the
skb_hwtstamps(skb)->hwtstamp.  This patch extends the same hwtstamp
access to the sockops prog.

In sockops, the skb is also available to the bpf prog during
the BPF_SOCK_OPS_PARSE_HDR_OPT_CB event.  There is a use case
that the hwtstamp will be useful to the sockops prog to better
measure the one-way-delay when the sender has put the tx
timestamp in the tcp header option.

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221107230420.4192307-2-martin.lau@linux.dev
parent e4c9cf0c

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -6445,6 +6445,7 @@ struct bpf_sock_ops { 
				 * the outgoing header has not

				 * been written yet.

				 */

	__u64 skb_hwtstamp;

};



/* Definitions for bpf_sock_ops_cb_flags */

net/core/filter.c

+31 −8
Original line number Diff line number Diff line
@@ -8925,6 +8925,10 @@ static bool sock_ops_is_valid_access(int off, int size, 
			bpf_ctx_record_field_size(info, size_default);

			return bpf_ctx_narrow_access_ok(off, size,

							size_default);

		case offsetof(struct bpf_sock_ops, skb_hwtstamp):

			if (size != sizeof(__u64))

				return false;

			break;

		default:

			if (size != size_default)

				return false;
@@ -9108,21 +9112,21 @@ static struct bpf_insn *bpf_convert_tstamp_type_read(const struct bpf_insn *si, 
	return insn;

}



static struct bpf_insn *bpf_convert_shinfo_access(const struct bpf_insn *si,

static struct bpf_insn *bpf_convert_shinfo_access(__u8 dst_reg, __u8 skb_reg,

						  struct bpf_insn *insn)

{

	/* si->dst_reg = skb_shinfo(SKB); */

#ifdef NET_SKBUFF_DATA_USES_OFFSET

	*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end),

			      BPF_REG_AX, si->src_reg,

			      BPF_REG_AX, skb_reg,

			      offsetof(struct sk_buff, end));

	*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, head),

			      si->dst_reg, si->src_reg,

			      dst_reg, skb_reg,

			      offsetof(struct sk_buff, head));

	*insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX);

	*insn++ = BPF_ALU64_REG(BPF_ADD, dst_reg, BPF_REG_AX);

#else

	*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, end),

			      si->dst_reg, si->src_reg,

			      dst_reg, skb_reg,

			      offsetof(struct sk_buff, end));

#endif
@@ -9515,7 +9519,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
		break;



	case offsetof(struct __sk_buff, gso_segs):

		insn = bpf_convert_shinfo_access(si, insn);

		insn = bpf_convert_shinfo_access(si->dst_reg, si->src_reg, insn);

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct skb_shared_info, gso_segs),

				      si->dst_reg, si->dst_reg,

				      bpf_target_off(struct skb_shared_info,
@@ -9523,7 +9527,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
						     target_size));

		break;

	case offsetof(struct __sk_buff, gso_size):

		insn = bpf_convert_shinfo_access(si, insn);

		insn = bpf_convert_shinfo_access(si->dst_reg, si->src_reg, insn);

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct skb_shared_info, gso_size),

				      si->dst_reg, si->dst_reg,

				      bpf_target_off(struct skb_shared_info,
@@ -9550,7 +9554,7 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
		BUILD_BUG_ON(sizeof_field(struct skb_shared_hwtstamps, hwtstamp) != 8);

		BUILD_BUG_ON(offsetof(struct skb_shared_hwtstamps, hwtstamp) != 0);



		insn = bpf_convert_shinfo_access(si, insn);

		insn = bpf_convert_shinfo_access(si->dst_reg, si->src_reg, insn);

		*insn++ = BPF_LDX_MEM(BPF_DW,

				      si->dst_reg, si->dst_reg,

				      bpf_target_off(struct skb_shared_info,
@@ -10400,6 +10404,25 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, 
						       tcp_flags),

				      si->dst_reg, si->dst_reg, off);

		break;

	case offsetof(struct bpf_sock_ops, skb_hwtstamp): {

		struct bpf_insn *jmp_on_null_skb;



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_sock_ops_kern,

						       skb),

				      si->dst_reg, si->src_reg,

				      offsetof(struct bpf_sock_ops_kern,

					       skb));

		/* Reserve one insn to test skb == NULL */

		jmp_on_null_skb = insn++;

		insn = bpf_convert_shinfo_access(si->dst_reg, si->dst_reg, insn);

		*insn++ = BPF_LDX_MEM(BPF_DW, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct skb_shared_info,

						     hwtstamps, 8,

						     target_size));

		*jmp_on_null_skb = BPF_JMP_IMM(BPF_JEQ, si->dst_reg, 0,

					       insn - jmp_on_null_skb - 1);

		break;

	}

	}

	return insn - insn_buf;

}

tools/include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -6445,6 +6445,7 @@ struct bpf_sock_ops { 
				 * the outgoing header has not

				 * been written yet.

				 */

	__u64 skb_hwtstamp;

};



/* Definitions for bpf_sock_ops_cb_flags */