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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