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/* SPDX-License-Identifier: GPL-2.0-only */
/* OpenVPN data channel offload
*
* Copyright (C) 2020-2025 OpenVPN, Inc.
*
* Author: James Yonan <james@openvpn.net>
* Antonio Quartulli <antonio@openvpn.net>
*/
#ifndef _NET_OVPN_OVPNCRYPTO_H_
#define _NET_OVPN_OVPNCRYPTO_H_
#include "pktid.h"
#include "proto.h"
/* info needed for both encrypt and decrypt directions */
struct ovpn_key_direction {
const u8 *cipher_key;
size_t cipher_key_size;
const u8 *nonce_tail; /* only needed for GCM modes */
size_t nonce_tail_size; /* only needed for GCM modes */
};
/* all info for a particular symmetric key (primary or secondary) */
struct ovpn_key_config {
enum ovpn_cipher_alg cipher_alg;
u8 key_id;
struct ovpn_key_direction encrypt;
struct ovpn_key_direction decrypt;
};
/* used to pass settings from netlink to the crypto engine */
struct ovpn_peer_key_reset {
enum ovpn_key_slot slot;
struct ovpn_key_config key;
};
struct ovpn_crypto_key_slot {
u8 key_id;
struct crypto_aead *encrypt;
struct crypto_aead *decrypt;
u8 nonce_tail_xmit[OVPN_NONCE_TAIL_SIZE];
u8 nonce_tail_recv[OVPN_NONCE_TAIL_SIZE];
struct ovpn_pktid_recv pid_recv ____cacheline_aligned_in_smp;
struct ovpn_pktid_xmit pid_xmit ____cacheline_aligned_in_smp;
struct kref refcount;
struct rcu_head rcu;
};
struct ovpn_crypto_state {
struct ovpn_crypto_key_slot __rcu *slots[2];
u8 primary_idx;
/* protects primary and secondary slots */
spinlock_t lock;
};
static inline bool ovpn_crypto_key_slot_hold(struct ovpn_crypto_key_slot *ks)
{
return kref_get_unless_zero(&ks->refcount);
}
static inline void ovpn_crypto_state_init(struct ovpn_crypto_state *cs)
{
RCU_INIT_POINTER(cs->slots[0], NULL);
RCU_INIT_POINTER(cs->slots[1], NULL);
cs->primary_idx = 0;
spin_lock_init(&cs->lock);
}
static inline struct ovpn_crypto_key_slot *
ovpn_crypto_key_id_to_slot(const struct ovpn_crypto_state *cs, u8 key_id)
{
struct ovpn_crypto_key_slot *ks;
u8 idx;
if (unlikely(!cs))
return NULL;
rcu_read_lock();
idx = READ_ONCE(cs->primary_idx);
ks = rcu_dereference(cs->slots[idx]);
if (ks && ks->key_id == key_id) {
if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
ks = NULL;
goto out;
}
ks = rcu_dereference(cs->slots[!idx]);
if (ks && ks->key_id == key_id) {
if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
ks = NULL;
goto out;
}
/* when both key slots are occupied but no matching key ID is found, ks
* has to be reset to NULL to avoid carrying a stale pointer
*/
ks = NULL;
out:
rcu_read_unlock();
return ks;
}
static inline struct ovpn_crypto_key_slot *
ovpn_crypto_key_slot_primary(const struct ovpn_crypto_state *cs)
{
struct ovpn_crypto_key_slot *ks;
rcu_read_lock();
ks = rcu_dereference(cs->slots[cs->primary_idx]);
if (unlikely(ks && !ovpn_crypto_key_slot_hold(ks)))
ks = NULL;
rcu_read_unlock();
return ks;
}
void ovpn_crypto_key_slot_release(struct kref *kref);
static inline void ovpn_crypto_key_slot_put(struct ovpn_crypto_key_slot *ks)
{
kref_put(&ks->refcount, ovpn_crypto_key_slot_release);
}
int ovpn_crypto_state_reset(struct ovpn_crypto_state *cs,
const struct ovpn_peer_key_reset *pkr);
void ovpn_crypto_key_slot_delete(struct ovpn_crypto_state *cs,
enum ovpn_key_slot slot);
void ovpn_crypto_state_release(struct ovpn_crypto_state *cs);
void ovpn_crypto_key_slots_swap(struct ovpn_crypto_state *cs);
int ovpn_crypto_config_get(struct ovpn_crypto_state *cs,
enum ovpn_key_slot slot,
struct ovpn_key_config *keyconf);
bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id);
#endif /* _NET_OVPN_OVPNCRYPTO_H_ */
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