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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>
135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Unstable XFRM state BPF helpers.
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*
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* Note that it is allowed to break compatibility for these functions since the
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* interface they 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.h>
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#include <linux/btf_ids.h>
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#include <net/xdp.h>
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#include <net/xfrm.h>
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/* bpf_xfrm_state_opts - Options for XFRM state lookup helpers
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*
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* Members:
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* @error - Out parameter, set for any errors encountered
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* Values:
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* -EINVAL - netns_id is less than -1
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* -EINVAL - opts__sz isn't BPF_XFRM_STATE_OPTS_SZ
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* -ENONET - No network namespace found for netns_id
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* -ENOENT - No xfrm_state found
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* @netns_id - Specify the network namespace for lookup
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* Values:
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* BPF_F_CURRENT_NETNS (-1)
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* Use namespace associated with ctx
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* [0, S32_MAX]
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* Network Namespace ID
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* @mark - XFRM mark to match on
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* @daddr - Destination address to match on
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* @spi - Security parameter index to match on
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* @proto - IP protocol to match on (eg. IPPROTO_ESP)
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* @family - Protocol family to match on (AF_INET/AF_INET6)
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*/
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struct bpf_xfrm_state_opts {
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s32 error;
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s32 netns_id;
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u32 mark;
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xfrm_address_t daddr;
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__be32 spi;
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u8 proto;
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u16 family;
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};
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enum {
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BPF_XFRM_STATE_OPTS_SZ = sizeof(struct bpf_xfrm_state_opts),
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};
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__bpf_kfunc_start_defs();
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/* bpf_xdp_get_xfrm_state - Get XFRM state
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*
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* A `struct xfrm_state *`, if found, must be released with a corresponding
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* bpf_xdp_xfrm_state_release.
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*
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* Parameters:
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* @ctx - Pointer to ctx (xdp_md) in XDP program
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* Cannot be NULL
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* @opts - Options for lookup (documented above)
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* Cannot be NULL
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* @opts__sz - Length of the bpf_xfrm_state_opts structure
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* Must be BPF_XFRM_STATE_OPTS_SZ
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*/
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__bpf_kfunc struct xfrm_state *
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bpf_xdp_get_xfrm_state(struct xdp_md *ctx, struct bpf_xfrm_state_opts *opts, u32 opts__sz)
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{
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struct xdp_buff *xdp = (struct xdp_buff *)ctx;
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struct net *net = dev_net(xdp->rxq->dev);
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struct xfrm_state *x;
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if (!opts || opts__sz < sizeof(opts->error))
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return NULL;
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if (opts__sz != BPF_XFRM_STATE_OPTS_SZ) {
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opts->error = -EINVAL;
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return NULL;
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}
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if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) {
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opts->error = -EINVAL;
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return NULL;
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}
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if (opts->netns_id >= 0) {
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net = get_net_ns_by_id(net, opts->netns_id);
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if (unlikely(!net)) {
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opts->error = -ENONET;
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return NULL;
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}
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}
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x = xfrm_state_lookup(net, opts->mark, &opts->daddr, opts->spi,
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opts->proto, opts->family);
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if (opts->netns_id >= 0)
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put_net(net);
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if (!x)
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opts->error = -ENOENT;
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return x;
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}
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/* bpf_xdp_xfrm_state_release - Release acquired xfrm_state object
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*
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* This must be invoked for referenced PTR_TO_BTF_ID, and the verifier rejects
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* the program if any references remain in the program in all of the explored
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* states.
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*
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* Parameters:
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* @x - Pointer to referenced xfrm_state object, obtained using
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* bpf_xdp_get_xfrm_state.
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*/
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__bpf_kfunc void bpf_xdp_xfrm_state_release(struct xfrm_state *x)
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{
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xfrm_state_put(x);
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}
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__bpf_kfunc_end_defs();
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BTF_KFUNCS_START(xfrm_state_kfunc_set)
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BTF_ID_FLAGS(func, bpf_xdp_get_xfrm_state, KF_RET_NULL | KF_ACQUIRE)
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BTF_ID_FLAGS(func, bpf_xdp_xfrm_state_release, KF_RELEASE)
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BTF_KFUNCS_END(xfrm_state_kfunc_set)
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static const struct btf_kfunc_id_set xfrm_state_xdp_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &xfrm_state_kfunc_set,
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};
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int __init register_xfrm_state_bpf(void)
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{
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return register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP,
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&xfrm_state_xdp_kfunc_set);
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}
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