[PATCH net-next v18 09/25] ovpn: implement packet processing

Antonio Quartulli
2025-01-13T09:31:17Z

This change implements encryption/decryption and
encapsulation/decapsulation of OpenVPN packets.

Support for generic crypto state is added along with
a wrapper for the AEAD crypto kernel API.

Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
drivers/net/Kconfig | 4 +
drivers/net/ovpn/Makefile | 3 +
drivers/net/ovpn/bind.c | 9 +-
drivers/net/ovpn/crypto.c | 152 +++++++++++++++++
drivers/net/ovpn/crypto.h | 139 ++++++++++++++++
drivers/net/ovpn/crypto_aead.c | 365 +++++++++++++++++++++++++++++++++++++++++
drivers/net/ovpn/crypto_aead.h | 31 ++++
drivers/net/ovpn/io.c | 149 +++++++++++++++--
drivers/net/ovpn/io.h | 3 +
drivers/net/ovpn/peer.c | 29 ++++
drivers/net/ovpn/peer.h | 5 +
drivers/net/ovpn/pktid.c | 129 +++++++++++++++
drivers/net/ovpn/pktid.h | 87 ++++++++++
drivers/net/ovpn/proto.h | 32 ++++
drivers/net/ovpn/skb.h | 4 +
15 files changed, 1124 insertions(+), 17 deletions(-)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index b18ff941944e2e92aa769d1ebbc3d1782611fc06..51d77f3c0848c3c9425b586c6a90cff99a744390 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -121,6 +121,10 @@ config OVPN
depends on IPV6 || !IPV6
select DST_CACHE
select NET_UDP_TUNNEL
+ select CRYPTO
+ select CRYPTO_AES
+ select CRYPTO_GCM
+ select CRYPTO_CHACHA20POLY1305
help
This module enhances the performance of the OpenVPN userspace software
by offloading the data channel processing to kernelspace.
diff --git a/drivers/net/ovpn/Makefile b/drivers/net/ovpn/Makefile
index 56bddc9bef83e0befde6af3c3565bb91731d7b22..ccdaeced1982c851475657860a005ff2b9dfbd13 100644
--- a/drivers/net/ovpn/Makefile
+++ b/drivers/net/ovpn/Makefile
@@ -8,10 +8,13 @@

obj-$(CONFIG_OVPN) := ovpn.o
ovpn-y += bind.o
+ovpn-y += crypto.o
+ovpn-y += crypto_aead.o
ovpn-y += main.o
ovpn-y += io.o
ovpn-y += netlink.o
ovpn-y += netlink-gen.o
ovpn-y += peer.o
+ovpn-y += pktid.o
ovpn-y += socket.o
ovpn-y += udp.o
diff --git a/drivers/net/ovpn/bind.c b/drivers/net/ovpn/bind.c
index b4d2ccec2ceddf43bc445b489cc62a578ef0ad0a..c8ca340cca936a357409e9458807f27831511975 100644
--- a/drivers/net/ovpn/bind.c
+++ b/drivers/net/ovpn/bind.c
@@ -48,11 +48,8 @@ struct ovpn_bind *ovpn_bind_from_sockaddr(const struct sockaddr_storage *ss)
*/
void ovpn_bind_reset(struct ovpn_peer *peer, struct ovpn_bind *new)
{
- struct ovpn_bind *old;
+ lockdep_assert_held(&peer->lock);

- spin_lock_bh(&peer->lock);
- old = rcu_replace_pointer(peer->bind, new, true);
- spin_unlock_bh(&peer->lock);
-
- kfree_rcu(old, rcu);
+ kfree_rcu(rcu_replace_pointer(peer->bind, new,
+ lockdep_is_held(&peer->lock)), rcu);
}
diff --git a/drivers/net/ovpn/crypto.c b/drivers/net/ovpn/crypto.c
new file mode 100644
index 0000000000000000000000000000000000000000..fabc19994ba34260753911ac7d3e50b643b9b89f
--- /dev/null
+++ b/drivers/net/ovpn/crypto.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 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 "ovpnstruct.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);
+ }
+}
+
+/* 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);
+}
+
+/* this swap is not atomic, but there will be a very short time frame where the
+ * old_secondary key won't be available. This should not be a big deal as most
+ * likely both peers are already using the new primary at this point.
+ */
+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 */
+ 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);
+}
diff --git a/drivers/net/ovpn/crypto.h b/drivers/net/ovpn/crypto.h
new file mode 100644
index 0000000000000000000000000000000000000000..33eb5bea59dc68110abfc5e940ffd841ac706388
--- /dev/null
+++ b/drivers/net/ovpn/crypto.h
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 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 = 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);
+
+#endif /* _NET_OVPN_OVPNCRYPTO_H_ */
diff --git a/drivers/net/ovpn/crypto_aead.c b/drivers/net/ovpn/crypto_aead.c
new file mode 100644
index 0000000000000000000000000000000000000000..03e35fa819e203efed4e79ac04f2be6040252312
--- /dev/null
+++ b/drivers/net/ovpn/crypto_aead.c
@@ -0,0 +1,365 @@
+// SPDX-License-Identifier: GPL-2.0
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ * Author: James Yonan <james@openvpn.net>
+ * Antonio Quartulli <antonio@openvpn.net>
+ */
+
+#include <crypto/aead.h>
+#include <linux/skbuff.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <net/udp.h>
+
+#include "ovpnstruct.h"
+#include "main.h"
+#include "io.h"
+#include "pktid.h"
+#include "crypto_aead.h"
+#include "crypto.h"
+#include "peer.h"
+#include "proto.h"
+#include "skb.h"
+
+#define OVPN_AUTH_TAG_SIZE 16
+#define OVPN_AAD_SIZE (OVPN_OPCODE_SIZE + OVPN_NONCE_WIRE_SIZE)
+
+#define ALG_NAME_AES "gcm(aes)"
+#define ALG_NAME_CHACHAPOLY "rfc7539(chacha20,poly1305)"
+
+static int ovpn_aead_encap_overhead(const struct ovpn_crypto_key_slot *ks)
+{
+ return OVPN_OPCODE_SIZE + /* OP header size */
+ sizeof(u32) + /* Packet ID */
+ crypto_aead_authsize(ks->encrypt); /* Auth Tag */
+}
+
+int ovpn_aead_encrypt(struct ovpn_peer *peer, struct ovpn_crypto_key_slot *ks,
+ struct sk_buff *skb)
+{
+ const unsigned int tag_size = crypto_aead_authsize(ks->encrypt);
+ struct aead_request *req;
+ struct sk_buff *trailer;
+ struct scatterlist *sg;
+ u8 iv[OVPN_NONCE_SIZE];
+ int nfrags, ret;
+ u32 pktid, op;
+
+ ovpn_skb_cb(skb)->peer = peer;
+ ovpn_skb_cb(skb)->ks = ks;
+
+ /* Sample AEAD header format:
+ * 48000001 00000005 7e7046bd 444a7e28 cc6387b1 64a4d6c1 380275a...
+ * [ OP32 ] [seq # ] [ auth tag ] [ payload ... ]
+ * [4-byte
+ * IV head]
+ */
+
+ /* check that there's enough headroom in the skb for packet
+ * encapsulation
+ */
+ if (unlikely(skb_cow_head(skb, OVPN_HEAD_ROOM)))
+ return -ENOBUFS;
+
+ /* get number of skb frags and ensure that packet data is writable */
+ nfrags = skb_cow_data(skb, 0, &trailer);
+ if (unlikely(nfrags < 0))
+ return nfrags;
+
+ if (unlikely(nfrags + 2 > (MAX_SKB_FRAGS + 2)))
+ return -ENOSPC;
+
+ ovpn_skb_cb(skb)->sg = kmalloc(sizeof(*ovpn_skb_cb(skb)->sg) *
+ (nfrags + 2), GFP_ATOMIC);
+ if (unlikely(!ovpn_skb_cb(skb)->sg))
+ return -ENOMEM;
+
+ sg = ovpn_skb_cb(skb)->sg;
+
+ /* sg table:
+ * 0: op, wire nonce (AD, len=OVPN_OP_SIZE_V2+OVPN_NONCE_WIRE_SIZE),
+ * 1, 2, 3, ..., n: payload,
+ * n+1: auth_tag (len=tag_size)
+ */
+ sg_init_table(sg, nfrags + 2);
+
+ /* build scatterlist to encrypt packet payload */
+ ret = skb_to_sgvec_nomark(skb, sg + 1, 0, skb->len);
+ if (unlikely(nfrags != ret)) {
+ ret = -EINVAL;
+ goto free_sg;
+ }
+
+ /* append auth_tag onto scatterlist */
+ __skb_push(skb, tag_size);
+ sg_set_buf(sg + nfrags + 1, skb->data, tag_size);
+
+ /* obtain packet ID, which is used both as a first
+ * 4 bytes of nonce and last 4 bytes of associated data.
+ */
+ ret = ovpn_pktid_xmit_next(&ks->pid_xmit, &pktid);
+ if (unlikely(ret < 0))
+ goto free_sg;
+
+ /* concat 4 bytes packet id and 8 bytes nonce tail into 12 bytes
+ * nonce
+ */
+ ovpn_pktid_aead_write(pktid, ks->nonce_tail_xmit, iv);
+
+ /* make space for packet id and push it to the front */
+ __skb_push(skb, OVPN_NONCE_WIRE_SIZE);
+ memcpy(skb->data, iv, OVPN_NONCE_WIRE_SIZE);
+
+ /* add packet op as head of additional data */
+ op = ovpn_opcode_compose(OVPN_DATA_V2, ks->key_id, peer->id);
+ __skb_push(skb, OVPN_OPCODE_SIZE);
+ BUILD_BUG_ON(sizeof(op) != OVPN_OPCODE_SIZE);
+ *((__force __be32 *)skb->data) = htonl(op);
+
+ /* AEAD Additional data */
+ sg_set_buf(sg, skb->data, OVPN_AAD_SIZE);
+
+ req = aead_request_alloc(ks->encrypt, GFP_ATOMIC);
+ if (unlikely(!req)) {
+ ret = -ENOMEM;
+ goto free_sg;
+ }
+
+ ovpn_skb_cb(skb)->req = req;
+
+ /* setup async crypto operation */
+ aead_request_set_tfm(req, ks->encrypt);
+ aead_request_set_callback(req, 0, ovpn_encrypt_post, skb);
+ aead_request_set_crypt(req, sg, sg,
+ skb->len - ovpn_aead_encap_overhead(ks), iv);
+ aead_request_set_ad(req, OVPN_AAD_SIZE);
+
+ /* encrypt it */
+ return crypto_aead_encrypt(req);
+free_sg:
+ kfree(ovpn_skb_cb(skb)->sg);
+ ovpn_skb_cb(skb)->sg = NULL;
+ return ret;
+}
+
+int ovpn_aead_decrypt(struct ovpn_peer *peer, struct ovpn_crypto_key_slot *ks,
+ struct sk_buff *skb)
+{
+ const unsigned int tag_size = crypto_aead_authsize(ks->decrypt);
+ int ret, payload_len, nfrags;
+ unsigned int payload_offset;
+ struct aead_request *req;
+ struct sk_buff *trailer;
+ struct scatterlist *sg;
+ u8 iv[OVPN_NONCE_SIZE];
+
+ payload_offset = OVPN_AAD_SIZE + tag_size;
+ payload_len = skb->len - payload_offset;
+
+ ovpn_skb_cb(skb)->payload_offset = payload_offset;
+ ovpn_skb_cb(skb)->peer = peer;
+ ovpn_skb_cb(skb)->ks = ks;
+
+ /* sanity check on packet size, payload size must be >= 0 */
+ if (unlikely(payload_len < 0))
+ return -EINVAL;
+
+ /* Prepare the skb data buffer to be accessed up until the auth tag.
+ * This is required because this area is directly mapped into the sg
+ * list.
+ */
+ if (unlikely(!pskb_may_pull(skb, payload_offset)))
+ return -ENODATA;
+
+ /* get number of skb frags and ensure that packet data is writable */
+ nfrags = skb_cow_data(skb, 0, &trailer);
+ if (unlikely(nfrags < 0))
+ return nfrags;
+
+ if (unlikely(nfrags + 2 > (MAX_SKB_FRAGS + 2)))
+ return -ENOSPC;
+
+ ovpn_skb_cb(skb)->sg = kmalloc(sizeof(*ovpn_skb_cb(skb)->sg) *
+ (nfrags + 2), GFP_ATOMIC);
+ if (unlikely(!ovpn_skb_cb(skb)->sg))
+ return -ENOMEM;
+
+ sg = ovpn_skb_cb(skb)->sg;
+
+ /* sg table:
+ * 0: op, wire nonce (AD, len=OVPN_OPCODE_SIZE+OVPN_NONCE_WIRE_SIZE),
+ * 1, 2, 3, ..., n: payload,
+ * n+1: auth_tag (len=tag_size)
+ */
+ sg_init_table(sg, nfrags + 2);
+
+ /* packet op is head of additional data */
+ sg_set_buf(sg, skb->data, OVPN_AAD_SIZE);
+
+ /* build scatterlist to decrypt packet payload */
+ ret = skb_to_sgvec_nomark(skb, sg + 1, payload_offset, payload_len);
+ if (unlikely(nfrags != ret)) {
+ ret = -EINVAL;
+ goto free_sg;
+ }
+
+ /* append auth_tag onto scatterlist */
+ sg_set_buf(sg + nfrags + 1, skb->data + OVPN_AAD_SIZE, tag_size);
+
+ /* copy nonce into IV buffer */
+ memcpy(iv, skb->data + OVPN_OPCODE_SIZE, OVPN_NONCE_WIRE_SIZE);
+ memcpy(iv + OVPN_NONCE_WIRE_SIZE, ks->nonce_tail_recv,
+ OVPN_NONCE_TAIL_SIZE);
+
+ req = aead_request_alloc(ks->decrypt, GFP_ATOMIC);
+ if (unlikely(!req)) {
+ ret = -ENOMEM;
+ goto free_sg;
+ }
+
+ ovpn_skb_cb(skb)->req = req;
+
+ /* setup async crypto operation */
+ aead_request_set_tfm(req, ks->decrypt);
+ aead_request_set_callback(req, 0, ovpn_decrypt_post, skb);
+ aead_request_set_crypt(req, sg, sg, payload_len + tag_size, iv);
+
+ aead_request_set_ad(req, OVPN_AAD_SIZE);
+
+ /* decrypt it */
+ return crypto_aead_decrypt(req);
+free_sg:
+ kfree(ovpn_skb_cb(skb)->sg);
+ ovpn_skb_cb(skb)->sg = NULL;
+ return ret;
+}
+
+/* Initialize a struct crypto_aead object */
+struct crypto_aead *ovpn_aead_init(const char *title, const char *alg_name,
+ const unsigned char *key,
+ unsigned int keylen)
+{
+ struct crypto_aead *aead;
+ int ret;
+
+ aead = crypto_alloc_aead(alg_name, 0, 0);
+ if (IS_ERR(aead)) {
+ ret = PTR_ERR(aead);
+ pr_err("%s crypto_alloc_aead failed, err=%d\n", title, ret);
+ aead = NULL;
+ goto error;
+ }
+
+ ret = crypto_aead_setkey(aead, key, keylen);
+ if (ret) {
+ pr_err("%s crypto_aead_setkey size=%u failed, err=%d\n", title,
+ keylen, ret);
+ goto error;
+ }
+
+ ret = crypto_aead_setauthsize(aead, OVPN_AUTH_TAG_SIZE);
+ if (ret) {
+ pr_err("%s crypto_aead_setauthsize failed, err=%d\n", title,
+ ret);
+ goto error;
+ }
+
+ /* basic AEAD assumption */
+ if (crypto_aead_ivsize(aead) != OVPN_NONCE_SIZE) {
+ pr_err("%s IV size must be %d\n", title, OVPN_NONCE_SIZE);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ pr_debug("********* Cipher %s (%s)\n", alg_name, title);
+ pr_debug("*** IV size=%u\n", crypto_aead_ivsize(aead));
+ pr_debug("*** req size=%u\n", crypto_aead_reqsize(aead));
+ pr_debug("*** block size=%u\n", crypto_aead_blocksize(aead));
+ pr_debug("*** auth size=%u\n", crypto_aead_authsize(aead));
+ pr_debug("*** alignmask=0x%x\n", crypto_aead_alignmask(aead));
+
+ return aead;
+
+error:
+ crypto_free_aead(aead);
+ return ERR_PTR(ret);
+}
+
+void ovpn_aead_crypto_key_slot_destroy(struct ovpn_crypto_key_slot *ks)
+{
+ if (!ks)
+ return;
+
+ crypto_free_aead(ks->encrypt);
+ crypto_free_aead(ks->decrypt);
+ kfree(ks);
+}
+
+struct ovpn_crypto_key_slot *
+ovpn_aead_crypto_key_slot_new(const struct ovpn_key_config *kc)
+{
+ struct ovpn_crypto_key_slot *ks = NULL;
+ const char *alg_name;
+ int ret;
+
+ /* validate crypto alg */
+ switch (kc->cipher_alg) {
+ case OVPN_CIPHER_ALG_AES_GCM:
+ alg_name = ALG_NAME_AES;
+ break;
+ case OVPN_CIPHER_ALG_CHACHA20_POLY1305:
+ alg_name = ALG_NAME_CHACHAPOLY;
+ break;
+ default:
+ return ERR_PTR(-EOPNOTSUPP);
+ }
+
+ if (kc->encrypt.nonce_tail_size != OVPN_NONCE_TAIL_SIZE ||
+ kc->decrypt.nonce_tail_size != OVPN_NONCE_TAIL_SIZE)
+ return ERR_PTR(-EINVAL);
+
+ /* build the key slot */
+ ks = kmalloc(sizeof(*ks), GFP_KERNEL);
+ if (!ks)
+ return ERR_PTR(-ENOMEM);
+
+ ks->encrypt = NULL;
+ ks->decrypt = NULL;
+ kref_init(&ks->refcount);
+ ks->key_id = kc->key_id;
+
+ ks->encrypt = ovpn_aead_init("encrypt", alg_name,
+ kc->encrypt.cipher_key,
+ kc->encrypt.cipher_key_size);
+ if (IS_ERR(ks->encrypt)) {
+ ret = PTR_ERR(ks->encrypt);
+ ks->encrypt = NULL;
+ goto destroy_ks;
+ }
+
+ ks->decrypt = ovpn_aead_init("decrypt", alg_name,
+ kc->decrypt.cipher_key,
+ kc->decrypt.cipher_key_size);
+ if (IS_ERR(ks->decrypt)) {
+ ret = PTR_ERR(ks->decrypt);
+ ks->decrypt = NULL;
+ goto destroy_ks;
+ }
+
+ memcpy(ks->nonce_tail_xmit, kc->encrypt.nonce_tail,
+ OVPN_NONCE_TAIL_SIZE);
+ memcpy(ks->nonce_tail_recv, kc->decrypt.nonce_tail,
+ OVPN_NONCE_TAIL_SIZE);
+
+ /* init packet ID generation/validation */
+ ovpn_pktid_xmit_init(&ks->pid_xmit);
+ ovpn_pktid_recv_init(&ks->pid_recv);
+
+ return ks;
+
+destroy_ks:
+ ovpn_aead_crypto_key_slot_destroy(ks);
+ return ERR_PTR(ret);
+}
diff --git a/drivers/net/ovpn/crypto_aead.h b/drivers/net/ovpn/crypto_aead.h
new file mode 100644
index 0000000000000000000000000000000000000000..77ee8141599bc06b0dc664c5b0a4dae660a89238
--- /dev/null
+++ b/drivers/net/ovpn/crypto_aead.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ * Author: James Yonan <james@openvpn.net>
+ * Antonio Quartulli <antonio@openvpn.net>
+ */
+
+#ifndef _NET_OVPN_OVPNAEAD_H_
+#define _NET_OVPN_OVPNAEAD_H_
+
+#include "crypto.h"
+
+#include <asm/types.h>
+#include <linux/skbuff.h>
+
+struct crypto_aead *ovpn_aead_init(const char *title, const char *alg_name,
+ const unsigned char *key,
+ unsigned int keylen);
+
+int ovpn_aead_encrypt(struct ovpn_peer *peer, struct ovpn_crypto_key_slot *ks,
+ struct sk_buff *skb);
+int ovpn_aead_decrypt(struct ovpn_peer *peer, struct ovpn_crypto_key_slot *ks,
+ struct sk_buff *skb);
+
+struct ovpn_crypto_key_slot *
+ovpn_aead_crypto_key_slot_new(const struct ovpn_key_config *kc);
+void ovpn_aead_crypto_key_slot_destroy(struct ovpn_crypto_key_slot *ks);
+
+#endif /* _NET_OVPN_OVPNAEAD_H_ */
diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c
index 9f5c6b06c79681048f750fce89e9683da41ea642..124292a49cd251a3b5021dc8828813941c187e54 100644
--- a/drivers/net/ovpn/io.c
+++ b/drivers/net/ovpn/io.c
@@ -7,6 +7,7 @@
* Antonio Quartulli <antonio@openvpn.net>
*/

+#include <crypto/aead.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/gro_cells.h>
@@ -15,6 +16,9 @@
#include "ovpnstruct.h"
#include "peer.h"
#include "io.h"
+#include "bind.h"
+#include "crypto.h"
+#include "crypto_aead.h"
#include "netlink.h"
#include "proto.h"
#include "udp.h"
@@ -44,7 +48,7 @@ static void ovpn_netdev_write(struct ovpn_peer *peer, struct sk_buff *skb)
skb_set_queue_mapping(skb, 0);
skb_scrub_packet(skb, true);

- skb_reset_network_header(skb);
+ /* network header reset in ovpn_decrypt_post() */
skb_reset_transport_header(skb);
skb_reset_inner_headers(skb);

@@ -56,33 +60,140 @@ static void ovpn_netdev_write(struct ovpn_peer *peer, struct sk_buff *skb)
dev_sw_netstats_rx_add(peer->ovpn->dev, pkt_len);
}

-static void ovpn_decrypt_post(struct sk_buff *skb, int ret)
+void ovpn_decrypt_post(void *data, int ret)
{
- struct ovpn_peer *peer = ovpn_skb_cb(skb)->peer;
+ struct ovpn_crypto_key_slot *ks;
+ unsigned int payload_offset = 0;
+ struct sk_buff *skb = data;
+ struct ovpn_peer *peer;
+ __be16 proto;
+ __be32 *pid;
+
+ /* crypto is happening asynchronously. this function will be called
+ * again later by the crypto callback with a proper return code
+ */
+ if (unlikely(ret == -EINPROGRESS))
+ return;
+
+ payload_offset = ovpn_skb_cb(skb)->payload_offset;
+ ks = ovpn_skb_cb(skb)->ks;
+ peer = ovpn_skb_cb(skb)->peer;
+
+ /* crypto is done, cleanup skb CB and its members */
+
+ if (likely(ovpn_skb_cb(skb)->sg))
+ kfree(ovpn_skb_cb(skb)->sg);
+
+ if (likely(ovpn_skb_cb(skb)->req))
+ aead_request_free(ovpn_skb_cb(skb)->req);

if (unlikely(ret < 0))
goto drop;

+ /* PID sits after the op */
+ pid = (__force __be32 *)(skb->data + OVPN_OPCODE_SIZE);
+ ret = ovpn_pktid_recv(&ks->pid_recv, ntohl(*pid), 0);
+ if (unlikely(ret < 0)) {
+ net_err_ratelimited("%s: PKT ID RX error for peer %u: %d\n",
+ netdev_name(peer->ovpn->dev), peer->id,
+ ret);
+ goto drop;
+ }
+
+ /* point to encapsulated IP packet */
+ __skb_pull(skb, payload_offset);
+
+ /* check if this is a valid datapacket that has to be delivered to the
+ * ovpn interface
+ */
+ skb_reset_network_header(skb);
+ proto = ovpn_ip_check_protocol(skb);
+ if (unlikely(!proto)) {
+ /* check if null packet */
+ if (unlikely(!pskb_may_pull(skb, 1))) {
+ net_info_ratelimited("%s: NULL packet received from peer %u\n",
+ netdev_name(peer->ovpn->dev),
+ peer->id);
+ goto drop;
+ }
+
+ net_info_ratelimited("%s: unsupported protocol received from peer %u\n",
+ netdev_name(peer->ovpn->dev), peer->id);
+ goto drop;
+ }
+ skb->protocol = proto;
+
+ /* perform Reverse Path Filtering (RPF) */
+ if (unlikely(!ovpn_peer_check_by_src(peer->ovpn, skb, peer))) {
+ if (skb->protocol == htons(ETH_P_IPV6))
+ net_dbg_ratelimited("%s: RPF dropped packet from peer %u, src: %pI6c\n",
+ netdev_name(peer->ovpn->dev),
+ peer->id, &ipv6_hdr(skb)->saddr);
+ else
+ net_dbg_ratelimited("%s: RPF dropped packet from peer %u, src: %pI4\n",
+ netdev_name(peer->ovpn->dev),
+ peer->id, &ip_hdr(skb)->saddr);
+ goto drop;
+ }
+
ovpn_netdev_write(peer, skb);
/* skb is passed to upper layer - don't free it */
skb = NULL;
drop:
if (unlikely(skb))
dev_core_stats_rx_dropped_inc(peer->ovpn->dev);
- ovpn_peer_put(peer);
+ if (likely(peer))
+ ovpn_peer_put(peer);
+ if (likely(ks))
+ ovpn_crypto_key_slot_put(ks);
kfree_skb(skb);
}

/* RX path entry point: decrypt packet and forward it to the device */
void ovpn_recv(struct ovpn_peer *peer, struct sk_buff *skb)
{
- ovpn_skb_cb(skb)->peer = peer;
- ovpn_decrypt_post(skb, 0);
+ struct ovpn_crypto_key_slot *ks;
+ u8 key_id;
+
+ /* get the key slot matching the key ID in the received packet */
+ key_id = ovpn_key_id_from_skb(skb);
+ ks = ovpn_crypto_key_id_to_slot(&peer->crypto, key_id);
+ if (unlikely(!ks)) {
+ net_info_ratelimited("%s: no available key for peer %u, key-id: %u\n",
+ netdev_name(peer->ovpn->dev), peer->id,
+ key_id);
+ dev_core_stats_rx_dropped_inc(peer->ovpn->dev);
+ kfree_skb(skb);
+ ovpn_peer_put(peer);
+ return;
+ }
+
+ memset(ovpn_skb_cb(skb), 0, sizeof(struct ovpn_cb));
+ ovpn_decrypt_post(skb, ovpn_aead_decrypt(peer, ks, skb));
}

-static void ovpn_encrypt_post(struct sk_buff *skb, int ret)
+void ovpn_encrypt_post(void *data, int ret)
{
- struct ovpn_peer *peer = ovpn_skb_cb(skb)->peer;
+ struct ovpn_crypto_key_slot *ks;
+ struct sk_buff *skb = data;
+ struct ovpn_peer *peer;
+
+ /* encryption is happening asynchronously. This function will be
+ * called later by the crypto callback with a proper return value
+ */
+ if (unlikely(ret == -EINPROGRESS))
+ return;
+
+ ks = ovpn_skb_cb(skb)->ks;
+ peer = ovpn_skb_cb(skb)->peer;
+
+ /* crypto is done, cleanup skb CB and its members */
+
+ if (likely(ovpn_skb_cb(skb)->sg))
+ kfree(ovpn_skb_cb(skb)->sg);
+
+ if (likely(ovpn_skb_cb(skb)->req))
+ aead_request_free(ovpn_skb_cb(skb)->req);

if (unlikely(ret < 0))
goto err;
@@ -102,13 +213,28 @@ static void ovpn_encrypt_post(struct sk_buff *skb, int ret)
err:
if (unlikely(skb))
dev_core_stats_tx_dropped_inc(peer->ovpn->dev);
- ovpn_peer_put(peer);
+ if (likely(peer))
+ ovpn_peer_put(peer);
+ if (likely(ks))
+ ovpn_crypto_key_slot_put(ks);
kfree_skb(skb);
}

static bool ovpn_encrypt_one(struct ovpn_peer *peer, struct sk_buff *skb)
{
- ovpn_skb_cb(skb)->peer = peer;
+ struct ovpn_crypto_key_slot *ks;
+
+ if (unlikely(skb->ip_summed == CHECKSUM_PARTIAL &&
+ skb_checksum_help(skb))) {
+ net_warn_ratelimited("%s: cannot compute checksum for outgoing packet for peer %u\n",
+ netdev_name(peer->ovpn->dev), peer->id);
+ return false;
+ }
+
+ /* get primary key to be used for encrypting data */
+ ks = ovpn_crypto_key_slot_primary(&peer->crypto);
+ if (unlikely(!ks))
+ return false;

/* take a reference to the peer because the crypto code may run async.
* ovpn_encrypt_post() will release it upon completion
@@ -118,7 +244,8 @@ static bool ovpn_encrypt_one(struct ovpn_peer *peer, struct sk_buff *skb)
return false;
}

- ovpn_encrypt_post(skb, 0);
+ memset(ovpn_skb_cb(skb), 0, sizeof(struct ovpn_cb));
+ ovpn_encrypt_post(skb, ovpn_aead_encrypt(peer, ks, skb));
return true;
}

diff --git a/drivers/net/ovpn/io.h b/drivers/net/ovpn/io.h
index b3830b787e16f3bdcaaff94e5bbe89be3e1006fe..5f9c7eba37b132bcf8c0ebad60af9171e46bf3e8 100644
--- a/drivers/net/ovpn/io.h
+++ b/drivers/net/ovpn/io.h
@@ -23,4 +23,7 @@ netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev);

void ovpn_recv(struct ovpn_peer *peer, struct sk_buff *skb);

+void ovpn_encrypt_post(void *data, int ret);
+void ovpn_decrypt_post(void *data, int ret);
+
#endif /* _NET_OVPN_OVPN_H_ */
diff --git a/drivers/net/ovpn/peer.c b/drivers/net/ovpn/peer.c
index 0bcdfaee773cedcecdbd43030dcefb7234541f52..b2a8a816e8b1d455f5917035b6ef34f771132158 100644
--- a/drivers/net/ovpn/peer.c
+++ b/drivers/net/ovpn/peer.c
@@ -12,6 +12,8 @@

#include "ovpnstruct.h"
#include "bind.h"
+#include "pktid.h"
+#include "crypto.h"
#include "io.h"
#include "main.h"
#include "netlink.h"
@@ -42,6 +44,7 @@ struct ovpn_peer *ovpn_peer_new(struct ovpn_priv *ovpn, u32 id)
peer->vpn_addrs.ipv6 = in6addr_any;

RCU_INIT_POINTER(peer->bind, NULL);
+ ovpn_crypto_state_init(&peer->crypto);
spin_lock_init(&peer->lock);
kref_init(&peer->refcount);

@@ -80,7 +83,10 @@ static void ovpn_peer_release_rcu(struct rcu_head *head)
*/
static void ovpn_peer_release(struct ovpn_peer *peer)
{
+ ovpn_crypto_state_release(&peer->crypto);
+ spin_lock_bh(&peer->lock);
ovpn_bind_reset(peer, NULL);
+ spin_unlock_bh(&peer->lock);
netdev_put(peer->ovpn->dev, &peer->dev_tracker);
call_rcu(&peer->rcu, ovpn_peer_release_rcu);
}
@@ -322,6 +328,29 @@ struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_priv *ovpn,
return peer;
}

+/**
+ * ovpn_peer_check_by_src - check that skb source is routed via peer
+ * @ovpn: the openvpn instance to search
+ * @skb: the packet to extract source address from
+ * @peer: the peer to check against the source address
+ *
+ * Return: true if the peer is matching or false otherwise
+ */
+bool ovpn_peer_check_by_src(struct ovpn_priv *ovpn, struct sk_buff *skb,
+ struct ovpn_peer *peer)
+{
+ bool match = false;
+
+ if (ovpn->mode == OVPN_MODE_P2P) {
+ /* in P2P mode, no matter the destination, packets are always
+ * sent to the single peer listening on the other side
+ */
+ match = (peer == rcu_access_pointer(ovpn->peer));
+ }
+
+ return match;
+}
+
/**
* ovpn_peer_add_p2p - add peer to related tables in a P2P instance
* @ovpn: the instance to add the peer to
diff --git a/drivers/net/ovpn/peer.h b/drivers/net/ovpn/peer.h
index 9591b4ced0f564014f85464c4cd94032369e9d02..275ec57a384f537cc5fbb675a8b5b3d6bc895caf 100644
--- a/drivers/net/ovpn/peer.h
+++ b/drivers/net/ovpn/peer.h
@@ -12,6 +12,7 @@

#include <net/dst_cache.h>

+#include "crypto.h"
#include "socket.h"

/**
@@ -23,6 +24,7 @@
* @vpn_addrs.ipv4: IPv4 assigned to peer on the tunnel
* @vpn_addrs.ipv6: IPv6 assigned to peer on the tunnel
* @sock: the socket being used to talk to this peer
+ * @crypto: the crypto configuration (ciphers, keys, etc..)
* @dst_cache: cache for dst_entry used to send to peer
* @bind: remote peer binding
* @delete_reason: why peer was deleted (i.e. timeout, transport error, ..)
@@ -40,6 +42,7 @@ struct ovpn_peer {
struct in6_addr ipv6;
} vpn_addrs;
struct ovpn_socket *sock;
+ struct ovpn_crypto_state crypto;
struct dst_cache dst_cache;
struct ovpn_bind __rcu *bind;
enum ovpn_del_peer_reason delete_reason;
@@ -82,5 +85,7 @@ struct ovpn_peer *ovpn_peer_get_by_transp_addr(struct ovpn_priv *ovpn,
struct ovpn_peer *ovpn_peer_get_by_id(struct ovpn_priv *ovpn, u32 peer_id);
struct ovpn_peer *ovpn_peer_get_by_dst(struct ovpn_priv *ovpn,
struct sk_buff *skb);
+bool ovpn_peer_check_by_src(struct ovpn_priv *ovpn, struct sk_buff *skb,
+ struct ovpn_peer *peer);

#endif /* _NET_OVPN_OVPNPEER_H_ */
diff --git a/drivers/net/ovpn/pktid.c b/drivers/net/ovpn/pktid.c
new file mode 100644
index 0000000000000000000000000000000000000000..0707a0489863d710fee05915007e4747f5bb4fa5
--- /dev/null
+++ b/drivers/net/ovpn/pktid.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ * Author: Antonio Quartulli <antonio@openvpn.net>
+ * James Yonan <james@openvpn.net>
+ */
+
+#include <linux/atomic.h>
+#include <linux/jiffies.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/types.h>
+
+#include "ovpnstruct.h"
+#include "main.h"
+#include "pktid.h"
+
+void ovpn_pktid_xmit_init(struct ovpn_pktid_xmit *pid)
+{
+ atomic64_set(&pid->seq_num, 1);
+}
+
+void ovpn_pktid_recv_init(struct ovpn_pktid_recv *pr)
+{
+ memset(pr, 0, sizeof(*pr));
+ spin_lock_init(&pr->lock);
+}
+
+/* Packet replay detection.
+ * Allows ID backtrack of up to REPLAY_WINDOW_SIZE - 1.
+ */
+int ovpn_pktid_recv(struct ovpn_pktid_recv *pr, u32 pkt_id, u32 pkt_time)
+{
+ const unsigned long now = jiffies;
+ int ret;
+
+ /* ID must not be zero */
+ if (unlikely(pkt_id == 0))
+ return -EINVAL;
+
+ spin_lock_bh(&pr->lock);
+
+ /* expire backtracks at or below pr->id after PKTID_RECV_EXPIRE time */
+ if (unlikely(time_after_eq(now, pr->expire)))
+ pr->id_floor = pr->id;
+
+ /* time changed? */
+ if (unlikely(pkt_time != pr->time)) {
+ if (pkt_time > pr->time) {
+ /* time moved forward, accept */
+ pr->base = 0;
+ pr->extent = 0;
+ pr->id = 0;
+ pr->time = pkt_time;
+ pr->id_floor = 0;
+ } else {
+ /* time moved backward, reject */
+ ret = -ETIME;
+ goto out;
+ }
+ }
+
+ if (likely(pkt_id == pr->id + 1)) {
+ /* well-formed ID sequence (incremented by 1) */
+ pr->base = REPLAY_INDEX(pr->base, -1);
+ pr->history[pr->base / 8] |= (1 << (pr->base % 8));
+ if (pr->extent < REPLAY_WINDOW_SIZE)
+ ++pr->extent;
+ pr->id = pkt_id;
+ } else if (pkt_id > pr->id) {
+ /* ID jumped forward by more than one */
+ const unsigned int delta = pkt_id - pr->id;
+
+ if (delta < REPLAY_WINDOW_SIZE) {
+ unsigned int i;
+
+ pr->base = REPLAY_INDEX(pr->base, -delta);
+ pr->history[pr->base / 8] |= (1 << (pr->base % 8));
+ pr->extent += delta;
+ if (pr->extent > REPLAY_WINDOW_SIZE)
+ pr->extent = REPLAY_WINDOW_SIZE;
+ for (i = 1; i < delta; ++i) {
+ unsigned int newb = REPLAY_INDEX(pr->base, i);
+
+ pr->history[newb / 8] &= ~BIT(newb % 8);
+ }
+ } else {
+ pr->base = 0;
+ pr->extent = REPLAY_WINDOW_SIZE;
+ memset(pr->history, 0, sizeof(pr->history));
+ pr->history[0] = 1;
+ }
+ pr->id = pkt_id;
+ } else {
+ /* ID backtrack */
+ const unsigned int delta = pr->id - pkt_id;
+
+ if (delta > pr->max_backtrack)
+ pr->max_backtrack = delta;
+ if (delta < pr->extent) {
+ if (pkt_id > pr->id_floor) {
+ const unsigned int ri = REPLAY_INDEX(pr->base,
+ delta);
+ u8 *p = &pr->history[ri / 8];
+ const u8 mask = (1 << (ri % 8));
+
+ if (*p & mask) {
+ ret = -EINVAL;
+ goto out;
+ }
+ *p |= mask;
+ } else {
+ ret = -EINVAL;
+ goto out;
+ }
+ } else {
+ ret = -EINVAL;
+ goto out;
+ }
+ }
+
+ pr->expire = now + PKTID_RECV_EXPIRE;
+ ret = 0;
+out:
+ spin_unlock_bh(&pr->lock);
+ return ret;
+}
diff --git a/drivers/net/ovpn/pktid.h b/drivers/net/ovpn/pktid.h
new file mode 100644
index 0000000000000000000000000000000000000000..ab38c59b6174074b8deb23e3e9ce47e96016ba94
--- /dev/null
+++ b/drivers/net/ovpn/pktid.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OpenVPN data channel offload
+ *
+ * Copyright (C) 2020-2024 OpenVPN, Inc.
+ *
+ * Author: Antonio Quartulli <antonio@openvpn.net>
+ * James Yonan <james@openvpn.net>
+ */
+
+#ifndef _NET_OVPN_OVPNPKTID_H_
+#define _NET_OVPN_OVPNPKTID_H_
+
+#include "proto.h"
+
+/* If no packets received for this length of time, set a backtrack floor
+ * at highest received packet ID thus far.
+ */
+#define PKTID_RECV_EXPIRE (30 * HZ)
+
+/* Packet-ID state for transmitter */
+struct ovpn_pktid_xmit {
+ atomic64_t seq_num;
+};
+
+/* replay window sizing in bytes = 2^REPLAY_WINDOW_ORDER */
+#define REPLAY_WINDOW_ORDER 8
+
+#define REPLAY_WINDOW_BYTES BIT(REPLAY_WINDOW_ORDER)
+#define REPLAY_WINDOW_SIZE (REPLAY_WINDOW_BYTES * 8)
+#define REPLAY_INDEX(base, i) (((base) + (i)) & (REPLAY_WINDOW_SIZE - 1))
+
+/* Packet-ID state for receiver.
+ * Other than lock member, can be zeroed to initialize.
+ */
+struct ovpn_pktid_recv {
+ /* "sliding window" bitmask of recent packet IDs received */
+ u8 history[REPLAY_WINDOW_BYTES];
+ /* bit position of deque base in history */
+ unsigned int base;
+ /* extent (in bits) of deque in history */
+ unsigned int extent;
+ /* expiration of history in jiffies */
+ unsigned long expire;
+ /* highest sequence number received */
+ u32 id;
+ /* highest time stamp received */
+ u32 time;
+ /* we will only accept backtrack IDs > id_floor */
+ u32 id_floor;
+ unsigned int max_backtrack;
+ /* protects entire pktd ID state */
+ spinlock_t lock;
+};
+
+/* Get the next packet ID for xmit */
+static inline int ovpn_pktid_xmit_next(struct ovpn_pktid_xmit *pid, u32 *pktid)
+{
+ const s64 seq_num = atomic64_fetch_add_unless(&pid->seq_num, 1,
+ 0x100000000LL);
+ /* when the 32bit space is over, we return an error because the packet
+ * ID is used to create the cipher IV and we do not want to reuse the
+ * same value more than once
+ */
+ if (unlikely(seq_num == 0x100000000LL))
+ return -ERANGE;
+
+ *pktid = (u32)seq_num;
+
+ return 0;
+}
+
+/* Write 12-byte AEAD IV to dest */
+static inline void ovpn_pktid_aead_write(const u32 pktid,
+ const u8 nt[],
+ unsigned char *dest)
+{
+ *(__force __be32 *)(dest) = htonl(pktid);
+ BUILD_BUG_ON(4 + OVPN_NONCE_TAIL_SIZE != OVPN_NONCE_SIZE);
+ memcpy(dest + 4, nt, OVPN_NONCE_TAIL_SIZE);
+}
+
+void ovpn_pktid_xmit_init(struct ovpn_pktid_xmit *pid);
+void ovpn_pktid_recv_init(struct ovpn_pktid_recv *pr);
+
+int ovpn_pktid_recv(struct ovpn_pktid_recv *pr, u32 pkt_id, u32 pkt_time);
+
+#endif /* _NET_OVPN_OVPNPKTID_H_ */
diff --git a/drivers/net/ovpn/proto.h b/drivers/net/ovpn/proto.h
index 34a812869b2e92e8bab0ebb87d46b67c3bbccf9f..9809e6cf752db4722659d201d58f221d83def2b8 100644
--- a/drivers/net/ovpn/proto.h
+++ b/drivers/net/ovpn/proto.h
@@ -83,4 +83,36 @@ static inline u32 ovpn_peer_id_from_skb(const struct sk_buff *skb, u16 offset)
return FIELD_GET(OVPN_OPCODE_PEERID_MASK, opcode);
}

+/**
+ * ovpn_key_id_from_skb - extract key ID from the skb head
+ * @skb: the packet to extract the key ID code from
+ *
+ * Note: this function assumes that the skb head was pulled enough
+ * to access the first byte.
+ *
+ * Return: the key ID
+ */
+static inline u8 ovpn_key_id_from_skb(const struct sk_buff *skb)
+{
+ u32 opcode = be32_to_cpu(*(__be32 *)skb->data);
+
+ return FIELD_GET(OVPN_OPCODE_KEYID_MASK, opcode);
+}
+
+/**
+ * ovpn_opcode_compose - combine OP code, key ID and peer ID to wire format
+ * @opcode: the OP code
+ * @key_id: the key ID
+ * @peer_id: the peer ID
+ *
+ * Return: a 4 bytes integer obtained combining all input values following the
+ * OpenVPN wire format. This integer can then be written to the packet header.
+ */
+static inline u32 ovpn_opcode_compose(u8 opcode, u8 key_id, u32 peer_id)
+{
+ return FIELD_PREP(OVPN_OPCODE_PKTTYPE_MASK, opcode) |
+ FIELD_PREP(OVPN_OPCODE_KEYID_MASK, key_id) |
+ FIELD_PREP(OVPN_OPCODE_PEERID_MASK, peer_id);
+}
+
#endif /* _NET_OVPN_OVPNPROTO_H_ */
diff --git a/drivers/net/ovpn/skb.h b/drivers/net/ovpn/skb.h
index af7b1f5b0ee6033ce980978667c3ee99a90e1d1b..fd19cc3081227e01c4c1ef25155de614b2dc2795 100644
--- a/drivers/net/ovpn/skb.h
+++ b/drivers/net/ovpn/skb.h
@@ -20,6 +20,10 @@

struct ovpn_cb {
struct ovpn_peer *peer;
+ struct ovpn_crypto_key_slot *ks;
+ struct aead_request *req;
+ struct scatterlist *sg;
+ unsigned int payload_offset;
};

static inline struct ovpn_cb *ovpn_skb_cb(struct sk_buff *skb)

--
2.45.2