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c50e96099e
Add two new kfuncs that allow a BPF tc-hook, installed on an ipip device in collect-metadata mode, to control FOU encap parameters on a per-packet level. The set of kfuncs is registered with the fou module. The bpf_skb_set_fou_encap kfunc is supposed to be used in tandem and after a successful call to the bpf_skb_set_tunnel_key bpf-helper. UDP source and destination ports can be controlled by passing a struct bpf_fou_encap. A source port of zero will auto-assign a source port. enum bpf_fou_encap_type is used to specify if the egress path should FOU or GUE encap the packet. On the ingress path bpf_skb_get_fou_encap can be used to read UDP source and destination ports from the receiver's point of view and allows for packet multiplexing across different destination ports within a single BPF program and ipip device. Signed-off-by: Christian Ehrig <cehrig@cloudflare.com> Link: https://lore.kernel.org/r/e17c94a646b63e78ce0dbf3f04b2c33dc948a32d.1680874078.git.cehrig@cloudflare.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Unstable Fou Helpers for TC-BPF hook
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*
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* These are called from SCHED_CLS BPF programs. Note that it is
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* allowed to break compatibility for these functions since the interface they
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* are exposed through to BPF programs is explicitly unstable.
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*/
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#include <linux/bpf.h>
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#include <linux/btf_ids.h>
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#include <net/dst_metadata.h>
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#include <net/fou.h>
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struct bpf_fou_encap {
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__be16 sport;
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__be16 dport;
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};
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enum bpf_fou_encap_type {
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FOU_BPF_ENCAP_FOU,
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FOU_BPF_ENCAP_GUE,
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};
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__diag_push();
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__diag_ignore_all("-Wmissing-prototypes",
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"Global functions as their definitions will be in BTF");
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/* bpf_skb_set_fou_encap - Set FOU encap parameters
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*
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* This function allows for using GUE or FOU encapsulation together with an
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* ipip device in collect-metadata mode.
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*
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* It is meant to be used in BPF tc-hooks and after a call to the
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* bpf_skb_set_tunnel_key helper, responsible for setting IP addresses.
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*
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* Parameters:
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* @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
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* @encap Pointer to a `struct bpf_fou_encap` storing UDP src and
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* dst ports. If sport is set to 0 the kernel will auto-assign a
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* port. This is similar to using `encap-sport auto`.
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* Cannot be NULL
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* @type Encapsulation type for the packet. Their definitions are
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* specified in `enum bpf_fou_encap_type`
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*/
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__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,
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struct bpf_fou_encap *encap, int type)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct ip_tunnel_info *info = skb_tunnel_info(skb);
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if (unlikely(!encap))
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return -EINVAL;
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if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX)))
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return -EINVAL;
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switch (type) {
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case FOU_BPF_ENCAP_FOU:
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info->encap.type = TUNNEL_ENCAP_FOU;
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break;
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case FOU_BPF_ENCAP_GUE:
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info->encap.type = TUNNEL_ENCAP_GUE;
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break;
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default:
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info->encap.type = TUNNEL_ENCAP_NONE;
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}
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if (info->key.tun_flags & TUNNEL_CSUM)
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info->encap.flags |= TUNNEL_ENCAP_FLAG_CSUM;
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info->encap.sport = encap->sport;
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info->encap.dport = encap->dport;
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return 0;
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}
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/* bpf_skb_get_fou_encap - Get FOU encap parameters
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*
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* This function allows for reading encap metadata from a packet received
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* on an ipip device in collect-metadata mode.
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*
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* Parameters:
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* @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
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* @encap Pointer to a struct bpf_fou_encap storing UDP source and
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* destination port. Cannot be NULL
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*/
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__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
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struct bpf_fou_encap *encap)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct ip_tunnel_info *info = skb_tunnel_info(skb);
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if (unlikely(!info))
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return -EINVAL;
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encap->sport = info->encap.sport;
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encap->dport = info->encap.dport;
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return 0;
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}
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__diag_pop()
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BTF_SET8_START(fou_kfunc_set)
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BTF_ID_FLAGS(func, bpf_skb_set_fou_encap)
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BTF_ID_FLAGS(func, bpf_skb_get_fou_encap)
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BTF_SET8_END(fou_kfunc_set)
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static const struct btf_kfunc_id_set fou_bpf_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &fou_kfunc_set,
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};
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int register_fou_bpf(void)
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{
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return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
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&fou_bpf_kfunc_set);
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}
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