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authorMartin KaFai Lau <kafai@fb.com>2022-03-02 11:56:34 -0800
committerDavid S. Miller <davem@davemloft.net>2022-03-03 14:38:49 +0000
commit8d21ec0e46ed6e39994accff8eb4f2be3d2e76b5 (patch)
treedae6bf8337a46b99796c22b7dae6265a3053701b /tools/include
parent7449197d600d30d038b1ce6285ab4747096eac7f (diff)
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 <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'tools/include')
-rw-r--r--tools/include/uapi/linux/bpf.h41
1 files changed, 40 insertions, 1 deletions
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;
};