1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*  OpenVPN data channel offload
3  *
4  *  Copyright (C) 2020-2025 OpenVPN, Inc.
5  *
6  *  Author:	James Yonan <james@openvpn.net>
7  *		Antonio Quartulli <antonio@openvpn.net>
8  */
9 
10 #ifndef _NET_OVPN_OVPNCRYPTO_H_
11 #define _NET_OVPN_OVPNCRYPTO_H_
12 
13 #include "pktid.h"
14 #include "proto.h"
15 
16 /* info needed for both encrypt and decrypt directions */
17 struct ovpn_key_direction {
18 	const u8 *cipher_key;
19 	size_t cipher_key_size;
20 	const u8 *nonce_tail; /* only needed for GCM modes */
21 	size_t nonce_tail_size; /* only needed for GCM modes */
22 };
23 
24 /* all info for a particular symmetric key (primary or secondary) */
25 struct ovpn_key_config {
26 	enum ovpn_cipher_alg cipher_alg;
27 	u8 key_id;
28 	struct ovpn_key_direction encrypt;
29 	struct ovpn_key_direction decrypt;
30 };
31 
32 /* used to pass settings from netlink to the crypto engine */
33 struct ovpn_peer_key_reset {
34 	enum ovpn_key_slot slot;
35 	struct ovpn_key_config key;
36 };
37 
38 struct ovpn_crypto_key_slot {
39 	u8 key_id;
40 
41 	struct crypto_aead *encrypt;
42 	struct crypto_aead *decrypt;
43 	u8 nonce_tail_xmit[OVPN_NONCE_TAIL_SIZE];
44 	u8 nonce_tail_recv[OVPN_NONCE_TAIL_SIZE];
45 
46 	struct ovpn_pktid_recv pid_recv ____cacheline_aligned_in_smp;
47 	struct ovpn_pktid_xmit pid_xmit ____cacheline_aligned_in_smp;
48 	struct kref refcount;
49 	struct rcu_head rcu;
50 };
51 
52 struct ovpn_crypto_state {
53 	struct ovpn_crypto_key_slot __rcu *slots[2];
54 	u8 primary_idx;
55 
56 	/* protects primary and secondary slots */
57 	spinlock_t lock;
58 };
59 
60 static inline bool ovpn_crypto_key_slot_hold(struct ovpn_crypto_key_slot *ks)
61 {
62 	return kref_get_unless_zero(&ks->refcount);
63 }
64 
65 static inline void ovpn_crypto_state_init(struct ovpn_crypto_state *cs)
66 {
67 	RCU_INIT_POINTER(cs->slots[0], NULL);
68 	RCU_INIT_POINTER(cs->slots[1], NULL);
69 	cs->primary_idx = 0;
70 	spin_lock_init(&cs->lock);
71 }
72 
73 static inline struct ovpn_crypto_key_slot *
74 ovpn_crypto_key_id_to_slot(const struct ovpn_crypto_state *cs, u8 key_id)
75 {
76 	struct ovpn_crypto_key_slot *ks;
77 	u8 idx;
78 
79 	if (unlikely(!cs))
80 		return NULL;
81 
82 	rcu_read_lock();
83 	idx = READ_ONCE(cs->primary_idx);
84 	ks = rcu_dereference(cs->slots[idx]);
85 	if (ks && ks->key_id == key_id) {
86 		if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
87 			ks = NULL;
88 		goto out;
89 	}
90 
91 	ks = rcu_dereference(cs->slots[!idx]);
92 	if (ks && ks->key_id == key_id) {
93 		if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
94 			ks = NULL;
95 		goto out;
96 	}
97 
98 	/* when both key slots are occupied but no matching key ID is found, ks
99 	 * has to be reset to NULL to avoid carrying a stale pointer
100 	 */
101 	ks = NULL;
102 out:
103 	rcu_read_unlock();
104 
105 	return ks;
106 }
107 
108 static inline struct ovpn_crypto_key_slot *
109 ovpn_crypto_key_slot_primary(const struct ovpn_crypto_state *cs)
110 {
111 	struct ovpn_crypto_key_slot *ks;
112 
113 	rcu_read_lock();
114 	ks = rcu_dereference(cs->slots[cs->primary_idx]);
115 	if (unlikely(ks && !ovpn_crypto_key_slot_hold(ks)))
116 		ks = NULL;
117 	rcu_read_unlock();
118 
119 	return ks;
120 }
121 
122 void ovpn_crypto_key_slot_release(struct kref *kref);
123 
124 static inline void ovpn_crypto_key_slot_put(struct ovpn_crypto_key_slot *ks)
125 {
126 	kref_put(&ks->refcount, ovpn_crypto_key_slot_release);
127 }
128 
129 int ovpn_crypto_state_reset(struct ovpn_crypto_state *cs,
130 			    const struct ovpn_peer_key_reset *pkr);
131 
132 void ovpn_crypto_key_slot_delete(struct ovpn_crypto_state *cs,
133 				 enum ovpn_key_slot slot);
134 
135 void ovpn_crypto_state_release(struct ovpn_crypto_state *cs);
136 
137 void ovpn_crypto_key_slots_swap(struct ovpn_crypto_state *cs);
138 
139 int ovpn_crypto_config_get(struct ovpn_crypto_state *cs,
140 			   enum ovpn_key_slot slot,
141 			   struct ovpn_key_config *keyconf);
142 
143 bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id);
144 
145 #endif /* _NET_OVPN_OVPNCRYPTO_H_ */
146