1// SPDX-License-Identifier: GPL-2.0-only
  2/* Unstable XFRM state BPF helpers.
  3 *
  4 * Note that it is allowed to break compatibility for these functions since the
  5 * interface they are exposed through to BPF programs is explicitly unstable.
  6 */
  7
  8#include <linux/bpf.h>
  9#include <linux/btf.h>
 10#include <linux/btf_ids.h>
 11#include <net/xdp.h>
 12#include <net/xfrm.h>
 13
 14/* bpf_xfrm_state_opts - Options for XFRM state lookup helpers
 15 *
 16 * Members:
 17 * @error      - Out parameter, set for any errors encountered
 18 *		 Values:
 19 *		   -EINVAL - netns_id is less than -1
 20 *		   -EINVAL - opts__sz isn't BPF_XFRM_STATE_OPTS_SZ
 21 *		   -ENONET - No network namespace found for netns_id
 22 *		   -ENOENT - No xfrm_state found
 23 * @netns_id	- Specify the network namespace for lookup
 24 *		 Values:
 25 *		   BPF_F_CURRENT_NETNS (-1)
 26 *		     Use namespace associated with ctx
 27 *		   [0, S32_MAX]
 28 *		     Network Namespace ID
 29 * @mark	- XFRM mark to match on
 30 * @daddr	- Destination address to match on
 31 * @spi		- Security parameter index to match on
 32 * @proto	- IP protocol to match on (eg. IPPROTO_ESP)
 33 * @family	- Protocol family to match on (AF_INET/AF_INET6)
 34 */
 35struct bpf_xfrm_state_opts {
 36	s32 error;
 37	s32 netns_id;
 38	u32 mark;
 39	xfrm_address_t daddr;
 40	__be32 spi;
 41	u8 proto;
 42	u16 family;
 43};
 44
 45enum {
 46	BPF_XFRM_STATE_OPTS_SZ = sizeof(struct bpf_xfrm_state_opts),
 47};
 48
 49__bpf_kfunc_start_defs();
 50
 51/* bpf_xdp_get_xfrm_state - Get XFRM state
 52 *
 53 * A `struct xfrm_state *`, if found, must be released with a corresponding
 54 * bpf_xdp_xfrm_state_release.
 55 *
 56 * Parameters:
 57 * @ctx	- Pointer to ctx (xdp_md) in XDP program
 58 *		    Cannot be NULL
 59 * @opts	- Options for lookup (documented above)
 60 *		    Cannot be NULL
 61 * @opts__sz	- Length of the bpf_xfrm_state_opts structure
 62 *		    Must be BPF_XFRM_STATE_OPTS_SZ
 63 */
 64__bpf_kfunc struct xfrm_state *
 65bpf_xdp_get_xfrm_state(struct xdp_md *ctx, struct bpf_xfrm_state_opts *opts, u32 opts__sz)
 66{
 67	struct xdp_buff *xdp = (struct xdp_buff *)ctx;
 68	struct net *net = dev_net(xdp->rxq->dev);
 69	struct xfrm_state *x;
 70
 71	if (!opts || opts__sz < sizeof(opts->error))
 72		return NULL;
 73
 74	if (opts__sz != BPF_XFRM_STATE_OPTS_SZ) {
 75		opts->error = -EINVAL;
 76		return NULL;
 77	}
 78
 79	if (unlikely(opts->netns_id < BPF_F_CURRENT_NETNS)) {
 80		opts->error = -EINVAL;
 81		return NULL;
 82	}
 83
 84	if (opts->netns_id >= 0) {
 85		net = get_net_ns_by_id(net, opts->netns_id);
 86		if (unlikely(!net)) {
 87			opts->error = -ENONET;
 88			return NULL;
 89		}
 90	}
 91
 92	x = xfrm_state_lookup(net, opts->mark, &opts->daddr, opts->spi,
 93			      opts->proto, opts->family);
 94
 95	if (opts->netns_id >= 0)
 96		put_net(net);
 97	if (!x)
 98		opts->error = -ENOENT;
 99
100	return x;
101}
102
103/* bpf_xdp_xfrm_state_release - Release acquired xfrm_state object
104 *
105 * This must be invoked for referenced PTR_TO_BTF_ID, and the verifier rejects
106 * the program if any references remain in the program in all of the explored
107 * states.
108 *
109 * Parameters:
110 * @x		- Pointer to referenced xfrm_state object, obtained using
111 *		  bpf_xdp_get_xfrm_state.
112 */
113__bpf_kfunc void bpf_xdp_xfrm_state_release(struct xfrm_state *x)
114{
115	xfrm_state_put(x);
116}
117
118__bpf_kfunc_end_defs();
119
120BTF_KFUNCS_START(xfrm_state_kfunc_set)
121BTF_ID_FLAGS(func, bpf_xdp_get_xfrm_state, KF_RET_NULL | KF_ACQUIRE)
122BTF_ID_FLAGS(func, bpf_xdp_xfrm_state_release, KF_RELEASE)
123BTF_KFUNCS_END(xfrm_state_kfunc_set)
124
125static const struct btf_kfunc_id_set xfrm_state_xdp_kfunc_set = {
126	.owner = THIS_MODULE,
127	.set   = &xfrm_state_kfunc_set,
128};
129
130int __init register_xfrm_state_bpf(void)
131{
132	return register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP,
133					 &xfrm_state_xdp_kfunc_set);
134}