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// SPDX-License-Identifier: GPL-2.0
/* OpenVPN data channel offload
*
* Copyright (C) 2020-2025 OpenVPN, Inc.
*
* Author: James Yonan <james@openvpn.net>
* Antonio Quartulli <antonio@openvpn.net>
*/
#include <linux/types.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <uapi/linux/ovpn.h>
#include "ovpnpriv.h"
#include "main.h"
#include "pktid.h"
#include "crypto_aead.h"
#include "crypto.h"
static void ovpn_ks_destroy_rcu(struct rcu_head *head)
{
struct ovpn_crypto_key_slot *ks;
ks = container_of(head, struct ovpn_crypto_key_slot, rcu);
ovpn_aead_crypto_key_slot_destroy(ks);
}
void ovpn_crypto_key_slot_release(struct kref *kref)
{
struct ovpn_crypto_key_slot *ks;
ks = container_of(kref, struct ovpn_crypto_key_slot, refcount);
call_rcu(&ks->rcu, ovpn_ks_destroy_rcu);
}
/* can only be invoked when all peer references have been dropped (i.e. RCU
* release routine)
*/
void ovpn_crypto_state_release(struct ovpn_crypto_state *cs)
{
struct ovpn_crypto_key_slot *ks;
ks = rcu_access_pointer(cs->slots[0]);
if (ks) {
RCU_INIT_POINTER(cs->slots[0], NULL);
ovpn_crypto_key_slot_put(ks);
}
ks = rcu_access_pointer(cs->slots[1]);
if (ks) {
RCU_INIT_POINTER(cs->slots[1], NULL);
ovpn_crypto_key_slot_put(ks);
}
}
/* removes the key matching the specified id from the crypto context */
bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id)
{
struct ovpn_crypto_key_slot *ks = NULL;
spin_lock_bh(&cs->lock);
if (rcu_access_pointer(cs->slots[0])->key_id == key_id) {
ks = rcu_replace_pointer(cs->slots[0], NULL,
lockdep_is_held(&cs->lock));
} else if (rcu_access_pointer(cs->slots[1])->key_id == key_id) {
ks = rcu_replace_pointer(cs->slots[1], NULL,
lockdep_is_held(&cs->lock));
}
spin_unlock_bh(&cs->lock);
if (ks)
ovpn_crypto_key_slot_put(ks);
/* let the caller know if a key was actually killed */
return ks;
}
/* Reset the ovpn_crypto_state object in a way that is atomic
* to RCU readers.
*/
int ovpn_crypto_state_reset(struct ovpn_crypto_state *cs,
const struct ovpn_peer_key_reset *pkr)
{
struct ovpn_crypto_key_slot *old = NULL, *new;
u8 idx;
if (pkr->slot != OVPN_KEY_SLOT_PRIMARY &&
pkr->slot != OVPN_KEY_SLOT_SECONDARY)
return -EINVAL;
new = ovpn_aead_crypto_key_slot_new(&pkr->key);
if (IS_ERR(new))
return PTR_ERR(new);
spin_lock_bh(&cs->lock);
idx = cs->primary_idx;
switch (pkr->slot) {
case OVPN_KEY_SLOT_PRIMARY:
old = rcu_replace_pointer(cs->slots[idx], new,
lockdep_is_held(&cs->lock));
break;
case OVPN_KEY_SLOT_SECONDARY:
old = rcu_replace_pointer(cs->slots[!idx], new,
lockdep_is_held(&cs->lock));
break;
}
spin_unlock_bh(&cs->lock);
if (old)
ovpn_crypto_key_slot_put(old);
return 0;
}
void ovpn_crypto_key_slot_delete(struct ovpn_crypto_state *cs,
enum ovpn_key_slot slot)
{
struct ovpn_crypto_key_slot *ks = NULL;
u8 idx;
if (slot != OVPN_KEY_SLOT_PRIMARY &&
slot != OVPN_KEY_SLOT_SECONDARY) {
pr_warn("Invalid slot to release: %u\n", slot);
return;
}
spin_lock_bh(&cs->lock);
idx = cs->primary_idx;
switch (slot) {
case OVPN_KEY_SLOT_PRIMARY:
ks = rcu_replace_pointer(cs->slots[idx], NULL,
lockdep_is_held(&cs->lock));
break;
case OVPN_KEY_SLOT_SECONDARY:
ks = rcu_replace_pointer(cs->slots[!idx], NULL,
lockdep_is_held(&cs->lock));
break;
}
spin_unlock_bh(&cs->lock);
if (!ks) {
pr_debug("Key slot already released: %u\n", slot);
return;
}
pr_debug("deleting key slot %u, key_id=%u\n", slot, ks->key_id);
ovpn_crypto_key_slot_put(ks);
}
void ovpn_crypto_key_slots_swap(struct ovpn_crypto_state *cs)
{
const struct ovpn_crypto_key_slot *old_primary, *old_secondary;
u8 idx;
spin_lock_bh(&cs->lock);
idx = cs->primary_idx;
old_primary = rcu_dereference_protected(cs->slots[idx],
lockdep_is_held(&cs->lock));
old_secondary = rcu_dereference_protected(cs->slots[!idx],
lockdep_is_held(&cs->lock));
/* perform real swap by switching the index of the primary key */
WRITE_ONCE(cs->primary_idx, !cs->primary_idx);
pr_debug("key swapped: (old primary) %d <-> (new primary) %d\n",
old_primary ? old_primary->key_id : -1,
old_secondary ? old_secondary->key_id : -1);
spin_unlock_bh(&cs->lock);
}
/**
* ovpn_crypto_config_get - populate keyconf object with non-sensible key data
* @cs: the crypto state to extract the key data from
* @slot: the specific slot to inspect
* @keyconf: the output object to populate
*
* Return: 0 on success or a negative error code otherwise
*/
int ovpn_crypto_config_get(struct ovpn_crypto_state *cs,
enum ovpn_key_slot slot,
struct ovpn_key_config *keyconf)
{
struct ovpn_crypto_key_slot *ks;
int idx;
switch (slot) {
case OVPN_KEY_SLOT_PRIMARY:
idx = cs->primary_idx;
break;
case OVPN_KEY_SLOT_SECONDARY:
idx = !cs->primary_idx;
break;
default:
return -EINVAL;
}
rcu_read_lock();
ks = rcu_dereference(cs->slots[idx]);
if (!ks) {
rcu_read_unlock();
return -ENOENT;
}
keyconf->cipher_alg = ovpn_aead_crypto_alg(ks);
keyconf->key_id = ks->key_id;
rcu_read_unlock();
return 0;
}
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