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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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89d3c0e461
IV wrap-around is cryptographically dangerous for a number of ciphers, therefore kill the key and inform userspace (via netlink) should the IV space go exhausted. Userspace has two ways of deciding when the key has to be renewed before exhausting the IV space: 1) time based approach: after X seconds/minutes userspace generates a new key and sends it to the kernel. This is based on guestimate and normally default timer value works well. 2) packet count based approach: after X packets/bytes userspace generates a new key and sends it to the kernel. Userspace keeps track of the amount of traffic by periodically polling GET_PEER and fetching the VPN/LINK stats. Signed-off-by: Antonio Quartulli <antonio@openvpn.net> Link: https://patch.msgid.link/20250415-b4-ovpn-v26-20-577f6097b964@openvpn.net Reviewed-by: Sabrina Dubroca <sd@queasysnail.net> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
145 lines
3.5 KiB
C
145 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* OpenVPN data channel offload
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*
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* Copyright (C) 2020-2025 OpenVPN, Inc.
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*
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* Author: James Yonan <james@openvpn.net>
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* Antonio Quartulli <antonio@openvpn.net>
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*/
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#ifndef _NET_OVPN_OVPNCRYPTO_H_
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#define _NET_OVPN_OVPNCRYPTO_H_
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#include "pktid.h"
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#include "proto.h"
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/* info needed for both encrypt and decrypt directions */
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struct ovpn_key_direction {
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const u8 *cipher_key;
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size_t cipher_key_size;
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const u8 *nonce_tail; /* only needed for GCM modes */
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size_t nonce_tail_size; /* only needed for GCM modes */
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};
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/* all info for a particular symmetric key (primary or secondary) */
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struct ovpn_key_config {
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enum ovpn_cipher_alg cipher_alg;
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u8 key_id;
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struct ovpn_key_direction encrypt;
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struct ovpn_key_direction decrypt;
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};
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/* used to pass settings from netlink to the crypto engine */
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struct ovpn_peer_key_reset {
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enum ovpn_key_slot slot;
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struct ovpn_key_config key;
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};
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struct ovpn_crypto_key_slot {
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u8 key_id;
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struct crypto_aead *encrypt;
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struct crypto_aead *decrypt;
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u8 nonce_tail_xmit[OVPN_NONCE_TAIL_SIZE];
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u8 nonce_tail_recv[OVPN_NONCE_TAIL_SIZE];
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struct ovpn_pktid_recv pid_recv ____cacheline_aligned_in_smp;
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struct ovpn_pktid_xmit pid_xmit ____cacheline_aligned_in_smp;
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struct kref refcount;
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struct rcu_head rcu;
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};
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struct ovpn_crypto_state {
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struct ovpn_crypto_key_slot __rcu *slots[2];
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u8 primary_idx;
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/* protects primary and secondary slots */
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spinlock_t lock;
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};
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static inline bool ovpn_crypto_key_slot_hold(struct ovpn_crypto_key_slot *ks)
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{
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return kref_get_unless_zero(&ks->refcount);
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}
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static inline void ovpn_crypto_state_init(struct ovpn_crypto_state *cs)
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{
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RCU_INIT_POINTER(cs->slots[0], NULL);
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RCU_INIT_POINTER(cs->slots[1], NULL);
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cs->primary_idx = 0;
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spin_lock_init(&cs->lock);
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}
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static inline struct ovpn_crypto_key_slot *
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ovpn_crypto_key_id_to_slot(const struct ovpn_crypto_state *cs, u8 key_id)
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{
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struct ovpn_crypto_key_slot *ks;
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u8 idx;
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if (unlikely(!cs))
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return NULL;
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rcu_read_lock();
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idx = READ_ONCE(cs->primary_idx);
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ks = rcu_dereference(cs->slots[idx]);
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if (ks && ks->key_id == key_id) {
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if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
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ks = NULL;
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goto out;
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}
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ks = rcu_dereference(cs->slots[!idx]);
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if (ks && ks->key_id == key_id) {
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if (unlikely(!ovpn_crypto_key_slot_hold(ks)))
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ks = NULL;
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goto out;
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}
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/* when both key slots are occupied but no matching key ID is found, ks
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* has to be reset to NULL to avoid carrying a stale pointer
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*/
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ks = NULL;
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out:
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rcu_read_unlock();
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return ks;
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}
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static inline struct ovpn_crypto_key_slot *
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ovpn_crypto_key_slot_primary(const struct ovpn_crypto_state *cs)
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{
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struct ovpn_crypto_key_slot *ks;
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rcu_read_lock();
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ks = rcu_dereference(cs->slots[cs->primary_idx]);
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if (unlikely(ks && !ovpn_crypto_key_slot_hold(ks)))
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ks = NULL;
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rcu_read_unlock();
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return ks;
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}
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void ovpn_crypto_key_slot_release(struct kref *kref);
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static inline void ovpn_crypto_key_slot_put(struct ovpn_crypto_key_slot *ks)
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{
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kref_put(&ks->refcount, ovpn_crypto_key_slot_release);
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}
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int ovpn_crypto_state_reset(struct ovpn_crypto_state *cs,
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const struct ovpn_peer_key_reset *pkr);
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void ovpn_crypto_key_slot_delete(struct ovpn_crypto_state *cs,
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enum ovpn_key_slot slot);
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void ovpn_crypto_state_release(struct ovpn_crypto_state *cs);
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void ovpn_crypto_key_slots_swap(struct ovpn_crypto_state *cs);
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int ovpn_crypto_config_get(struct ovpn_crypto_state *cs,
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enum ovpn_key_slot slot,
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struct ovpn_key_config *keyconf);
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bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id);
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#endif /* _NET_OVPN_OVPNCRYPTO_H_ */
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