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>
111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Unstable XFRM 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/xfrm.h>
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/* bpf_xfrm_info - XFRM metadata information
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*
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* Members:
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* @if_id - XFRM if_id:
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* Transmit: if_id to be used in policy and state lookups
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* Receive: if_id of the state matched for the incoming packet
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* @link - Underlying device ifindex:
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* Transmit: used as the underlying device in VRF routing
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* Receive: the device on which the packet had been received
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*/
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struct bpf_xfrm_info {
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u32 if_id;
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int link;
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};
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__bpf_kfunc_start_defs();
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/* bpf_skb_get_xfrm_info - Get XFRM metadata
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*
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* Parameters:
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* @skb_ctx - Pointer to ctx (__sk_buff) in TC program
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* Cannot be NULL
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* @to - Pointer to memory to which the metadata will be copied
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* Cannot be NULL
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*/
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__bpf_kfunc int bpf_skb_get_xfrm_info(struct __sk_buff *skb_ctx, struct bpf_xfrm_info *to)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct xfrm_md_info *info;
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info = skb_xfrm_md_info(skb);
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if (!info)
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return -EINVAL;
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to->if_id = info->if_id;
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to->link = info->link;
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return 0;
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}
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/* bpf_skb_get_xfrm_info - Set XFRM metadata
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*
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* Parameters:
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* @skb_ctx - Pointer to ctx (__sk_buff) in TC program
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* Cannot be NULL
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* @from - Pointer to memory from which the metadata will be copied
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* Cannot be NULL
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*/
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__bpf_kfunc int bpf_skb_set_xfrm_info(struct __sk_buff *skb_ctx, const struct bpf_xfrm_info *from)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct metadata_dst *md_dst;
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struct xfrm_md_info *info;
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if (unlikely(skb_metadata_dst(skb)))
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return -EINVAL;
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if (!xfrm_bpf_md_dst) {
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struct metadata_dst __percpu *tmp;
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tmp = metadata_dst_alloc_percpu(0, METADATA_XFRM, GFP_ATOMIC);
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if (!tmp)
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return -ENOMEM;
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if (cmpxchg(&xfrm_bpf_md_dst, NULL, tmp))
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metadata_dst_free_percpu(tmp);
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}
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md_dst = this_cpu_ptr(xfrm_bpf_md_dst);
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info = &md_dst->u.xfrm_info;
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info->if_id = from->if_id;
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info->link = from->link;
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skb_dst_force(skb);
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info->dst_orig = skb_dst(skb);
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dst_hold((struct dst_entry *)md_dst);
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skb_dst_set(skb, (struct dst_entry *)md_dst);
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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(xfrm_ifc_kfunc_set)
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BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info)
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BTF_ID_FLAGS(func, bpf_skb_set_xfrm_info)
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BTF_KFUNCS_END(xfrm_ifc_kfunc_set)
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static const struct btf_kfunc_id_set xfrm_interface_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &xfrm_ifc_kfunc_set,
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};
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int __init register_xfrm_interface_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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&xfrm_interface_kfunc_set);
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}
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