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Date: Mon, 7 Nov 2022 15:04:18 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: bpf@...r.kernel.org
Cc: 'Alexei Starovoitov ' <ast@...nel.org>,
'Andrii Nakryiko ' <andrii@...nel.org>,
'Daniel Borkmann ' <daniel@...earbox.net>,
netdev@...r.kernel.org, kernel-team@...a.com
Subject: [PATCH v2 bpf-next 1/3] bpf: Add hwtstamp field for the sockops prog
From: Martin KaFai Lau <martin.lau@...nel.org>
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: Martin KaFai Lau <martin.lau@...nel.org>
---
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 39 +++++++++++++++++++++++++++-------
tools/include/uapi/linux/bpf.h | 1 +
3 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 94659f6b3395..fb4c911d2a03 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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 */
diff --git a/net/core/filter.c b/net/core/filter.c
index cb3b635e35be..cd667cdbdb26 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 94659f6b3395..fb4c911d2a03 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -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 */
--
2.30.2
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