From 8d21ec0e46ed6e39994accff8eb4f2be3d2e76b5 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 2 Mar 2022 11:56:34 -0800 Subject: bpf: Add __sk_buff->delivery_time_type and bpf_skb_set_skb_delivery_time() * __sk_buff->delivery_time_type: This patch adds __sk_buff->delivery_time_type. It tells if the delivery_time is stored in __sk_buff->tstamp or not. It will be most useful for ingress to tell if the __sk_buff->tstamp has the (rcv) timestamp or delivery_time. If delivery_time_type is 0 (BPF_SKB_DELIVERY_TIME_NONE), it has the (rcv) timestamp. Two non-zero types are defined for the delivery_time_type, BPF_SKB_DELIVERY_TIME_MONO and BPF_SKB_DELIVERY_TIME_UNSPEC. For UNSPEC, it can only happen in egress because only mono delivery_time can be forwarded to ingress now. The clock of UNSPEC delivery_time can be deduced from the skb->sk->sk_clockid which is how the sch_etf doing it also. * Provide forwarded delivery_time to tc-bpf@ingress: With the help of the new delivery_time_type, the tc-bpf has a way to tell if the __sk_buff->tstamp has the (rcv) timestamp or the delivery_time. During bpf load time, the verifier will learn if the bpf prog has accessed the new __sk_buff->delivery_time_type. If it does, it means the tc-bpf@ingress is expecting the skb->tstamp could have the delivery_time. The kernel will then read the skb->tstamp as-is during bpf insn rewrite without checking the skb->mono_delivery_time. This is done by adding a new prog->delivery_time_access bit. The same goes for writing skb->tstamp. * bpf_skb_set_delivery_time(): The bpf_skb_set_delivery_time() helper is added to allow setting both delivery_time and the delivery_time_type at the same time. If the tc-bpf does not need to change the delivery_time_type, it can directly write to the __sk_buff->tstamp as the existing tc-bpf has already been doing. It will be most useful at ingress to change the __sk_buff->tstamp from the (rcv) timestamp to a mono delivery_time and then bpf_redirect_*(). bpf only has mono clock helper (bpf_ktime_get_ns), and the current known use case is the mono EDT for fq, and only mono delivery time can be kept during forward now, so bpf_skb_set_delivery_time() only supports setting BPF_SKB_DELIVERY_TIME_MONO. It can be extended later when use cases come up and the forwarding path also supports other clock bases. Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller --- tools/include/uapi/linux/bpf.h | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) (limited to 'tools/include') diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index afe3d0d7f5f2..4eebea830613 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -5086,6 +5086,37 @@ union bpf_attr { * Return * 0 on success, or a negative error in case of failure. On error * *dst* buffer is zeroed out. + * + * long bpf_skb_set_delivery_time(struct sk_buff *skb, u64 dtime, u32 dtime_type) + * Description + * Set a *dtime* (delivery time) to the __sk_buff->tstamp and also + * change the __sk_buff->delivery_time_type to *dtime_type*. + * + * When setting a delivery time (non zero *dtime*) to + * __sk_buff->tstamp, only BPF_SKB_DELIVERY_TIME_MONO *dtime_type* + * is supported. It is the only delivery_time_type that will be + * kept after bpf_redirect_*(). + * + * If there is no need to change the __sk_buff->delivery_time_type, + * the delivery time can be directly written to __sk_buff->tstamp + * instead. + * + * *dtime* 0 and *dtime_type* BPF_SKB_DELIVERY_TIME_NONE + * can be used to clear any delivery time stored in + * __sk_buff->tstamp. + * + * Only IPv4 and IPv6 skb->protocol are supported. + * + * This function is most useful when it needs to set a + * mono delivery time to __sk_buff->tstamp and then + * bpf_redirect_*() to the egress of an iface. For example, + * changing the (rcv) timestamp in __sk_buff->tstamp at + * ingress to a mono delivery time and then bpf_redirect_*() + * to sch_fq@phy-dev. + * Return + * 0 on success. + * **-EINVAL** for invalid input + * **-EOPNOTSUPP** for unsupported delivery_time_type and protocol */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -5280,6 +5311,7 @@ union bpf_attr { FN(xdp_load_bytes), \ FN(xdp_store_bytes), \ FN(copy_from_user_task), \ + FN(skb_set_delivery_time), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -5469,6 +5501,12 @@ union { \ __u64 :64; \ } __attribute__((aligned(8))) +enum { + BPF_SKB_DELIVERY_TIME_NONE, + BPF_SKB_DELIVERY_TIME_UNSPEC, + BPF_SKB_DELIVERY_TIME_MONO, +}; + /* user accessible mirror of in-kernel sk_buff. * new fields can only be added to the end of this structure */ @@ -5509,7 +5547,8 @@ struct __sk_buff { __u32 gso_segs; __bpf_md_ptr(struct bpf_sock *, sk); __u32 gso_size; - __u32 :32; /* Padding, future use. */ + __u8 delivery_time_type; + __u32 :24; /* Padding, future use. */ __u64 hwtstamp; }; -- cgit v1.2.3