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6f3189f38a
This commit marks kfuncs as such inside the .BTF_ids section. The upshot of these annotations is that we'll be able to automatically generate kfunc prototypes for downstream users. The process is as follows: 1. In source, use BTF_KFUNCS_START/END macro pair to mark kfuncs 2. During build, pahole injects into BTF a "bpf_kfunc" BTF_DECL_TAG for each function inside BTF_KFUNCS sets 3. At runtime, vmlinux or module BTF is made available in sysfs 4. At runtime, bpftool (or similar) can look at provided BTF and generate appropriate prototypes for functions with "bpf_kfunc" tag To ensure future kfunc are similarly tagged, we now also return error inside kfunc registration for untagged kfuncs. For vmlinux kfuncs, we also WARN(), as initcall machinery does not handle errors. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Acked-by: Benjamin Tissoires <bentiss@kernel.org> Link: https://lore.kernel.org/r/e55150ceecbf0a5d961e608941165c0bee7bc943.1706491398.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov <ast@kernel.org>
118 lines
3.0 KiB
C
118 lines
3.0 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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__bpf_kfunc_start_defs();
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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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__bpf_kfunc_end_defs();
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BTF_KFUNCS_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_KFUNCS_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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