Commit f64c4ace authored by Vadim Fedorenko's avatar Vadim Fedorenko Committed by Daniel Borkmann
Browse files

bpf: Add hardware timestamp field to __sk_buff 



BPF programs may want to know hardware timestamps if NIC supports
such timestamping.

Expose this data as hwtstamp field of __sk_buff the same way as
gso_segs/gso_size. This field could be accessed from the same
programs as tstamp field, but it's read-only field. Explicit test
to deny access to padding data is added to bpf_skb_is_valid_access.

Also update BPF_PROG_TEST_RUN tests of the feature.

Signed-off-by: default avatarVadim Fedorenko <vfedorenko@novek.ru>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210909220409.8804-2-vfedorenko@novek.ru
parent e876a036

include/uapi/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -5284,6 +5284,8 @@ struct __sk_buff { 
	__u32 gso_segs;

	__bpf_md_ptr(struct bpf_sock *, sk);

	__u32 gso_size;

	__u32 :32;		/* Padding, future use. */

	__u64 hwtstamp;

};



struct bpf_tunnel_key {

net/core/filter.c

+21 −0
Original line number Diff line number Diff line
@@ -7765,6 +7765,10 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type 
		break;

	case bpf_ctx_range_ptr(struct __sk_buff, flow_keys):

		return false;

	case bpf_ctx_range(struct __sk_buff, hwtstamp):

		if (type == BPF_WRITE || size != sizeof(__u64))

			return false;

		break;

	case bpf_ctx_range(struct __sk_buff, tstamp):

		if (size != sizeof(__u64))

			return false;
@@ -7774,6 +7778,9 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type 
			return false;

		info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;

		break;

	case offsetofend(struct __sk_buff, gso_size) ... offsetof(struct __sk_buff, hwtstamp) - 1:

		/* Explicitly prohibit access to padding in __sk_buff. */

		return false;

	default:

		/* Only narrow read access allowed for now. */

		if (type == BPF_WRITE) {
@@ -7802,6 +7809,7 @@ static bool sk_filter_is_valid_access(int off, int size, 
	case bpf_ctx_range_till(struct __sk_buff, family, local_port):

	case bpf_ctx_range(struct __sk_buff, tstamp):

	case bpf_ctx_range(struct __sk_buff, wire_len):

	case bpf_ctx_range(struct __sk_buff, hwtstamp):

		return false;

	}
@@ -7872,6 +7880,7 @@ static bool lwt_is_valid_access(int off, int size, 
	case bpf_ctx_range(struct __sk_buff, data_meta):

	case bpf_ctx_range(struct __sk_buff, tstamp):

	case bpf_ctx_range(struct __sk_buff, wire_len):

	case bpf_ctx_range(struct __sk_buff, hwtstamp):

		return false;

	}
@@ -8373,6 +8382,7 @@ static bool sk_skb_is_valid_access(int off, int size, 
	case bpf_ctx_range(struct __sk_buff, data_meta):

	case bpf_ctx_range(struct __sk_buff, tstamp):

	case bpf_ctx_range(struct __sk_buff, wire_len):

	case bpf_ctx_range(struct __sk_buff, hwtstamp):

		return false;

	}
@@ -8884,6 +8894,17 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		break;

	case offsetof(struct __sk_buff, hwtstamp):

		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_LDX_MEM(BPF_DW,

				      si->dst_reg, si->dst_reg,

				      bpf_target_off(struct skb_shared_info,

						     hwtstamps, 8,

						     target_size));

		break;

	}



	return insn - insn_buf;

tools/include/uapi/linux/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -5284,6 +5284,8 @@ struct __sk_buff { 
	__u32 gso_segs;

	__bpf_md_ptr(struct bpf_sock *, sk);

	__u32 gso_size;

	__u32 :32;		/* Padding, future use. */

	__u64 hwtstamp;

};



struct bpf_tunnel_key {