Re: [PATCH net-next v24 09/23] ovpn: implement packet processing

Hi Antonio,

On Tue, 18 Mar 2025 02:40:44 +0100, Antonio Quartulli wrote:

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 | 392 +++++++++++++++++++++++++++++++++++++++++ drivers/net/ovpn/crypto_aead.h | 27 +++ 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 | 5 + 15 files changed, 1148 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 164f2058ea8e6dc5b9287afb59758a268b2f8b56..38c9fdca0e2e8e4af3c369ceb3971b58ab52d77b 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 d4a1aeed12c99c71eaf5e8e9fc9c0fe61af6aaac..24d2788a277e674bde80b5aac9407c6528b108e5 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..db243cb48142f4a20aaf7a29eadda1b19ea344a7 --- /dev/null +++ b/drivers/net/ovpn/crypto.c @@ -0,0 +1,152 @@ +// SPDX-License-Identifier: GPL-2.0 +/* OpenVPN data channel offload

• • Copyright (C) 2020-2025 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);
  

• }

+}

+/* 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 */
• 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);

+} diff --git a/drivers/net/ovpn/crypto.h b/drivers/net/ovpn/crypto.h new file mode 100644 index 0000000000000000000000000000000000000000..5155791b87df7cccc76a011fa751686180074982 --- /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) 2020-2025 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);

+#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..e87e33f49c3088a21f7032e9fd9b2bb0aa50ef83 --- /dev/null +++ b/drivers/net/ovpn/crypto_aead.c @@ -0,0 +1,392 @@ +// 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 <crypto/aead.h> +#include <linux/skbuff.h> +#include <net/ip.h> +#include <net/ipv6.h> +#include <net/udp.h>

+#include "ovpnpriv.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;
• int nfrags, ret;
• u32 pktid, op;
• u8 *iv;
• 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;
  

• /* sg may be required by async crypto */
• 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;
  

• /* iv may be required by async crypto */
• ovpn_skb_cb(skb)->iv = kmalloc(OVPN_NONCE_SIZE, GFP_ATOMIC);
• if (unlikely(!ovpn_skb_cb(skb)->iv)) {

• ret = -ENOMEM;
  

• goto free_sg;
  

• }
• iv = ovpn_skb_cb(skb)->iv;
• /* 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_iv;
  

• }
• 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_iv:

• kfree(ovpn_skb_cb(skb)->iv);
• ovpn_skb_cb(skb)->iv = NULL;

+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;
• 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;
  

• /* sg may be required by async crypto */
• 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);
• /* iv may be required by async crypto */
• ovpn_skb_cb(skb)->iv = kmalloc(OVPN_NONCE_SIZE, GFP_ATOMIC);
• if (unlikely(!ovpn_skb_cb(skb)->iv)) {

• ret = -ENOMEM;
  

• goto free_sg;
  

• }
• iv = ovpn_skb_cb(skb)->iv;
• /* 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_iv;
  

• }
• 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_iv:

• kfree(ovpn_skb_cb(skb)->iv);
• ovpn_skb_cb(skb)->iv = NULL;

+free_sg:

• kfree(ovpn_skb_cb(skb)->sg);
• ovpn_skb_cb(skb)->sg = NULL;
• return ret;

+}

+/* Initialize a struct crypto_aead object */ +static 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..40c056558add3b9d17fda5c43eb858cb44c95945 --- /dev/null +++ b/drivers/net/ovpn/crypto_aead.h @@ -0,0 +1,27 @@ +/* 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_OVPNAEAD_H_ +#define _NET_OVPN_OVPNAEAD_H_

+#include "crypto.h"

+#include <asm/types.h> +#include <linux/skbuff.h>

+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 46ad27e8eb8425f810c7d2b6c63984ea008d90fa..f8113f160148c5953c40f69a87a3ed7ce62abacb 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 "ovpnpriv.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);

@@ -56,34 +60,147 @@ 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)->iv))

• kfree(ovpn_skb_cb(skb)->iv);
  

NULL check before kfree is unnecessary, as kfree(NULL) is a noop.

• 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);
  

Likewise.

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_socket *sock;
• 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)->iv))

• kfree(ovpn_skb_cb(skb)->iv);
  

• 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; @@ -110,23 +227,33 @@ 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;
• /* 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 */ if (unlikely(!ovpn_peer_hold(peer))) { DEBUG_NET_WARN_ON_ONCE(1);

• ovpn_crypto_key_slot_put(ks);
  

  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 1cfa66873a2d4840ce57e337f8b4e8143e8b8e79..5143104b2c4b896a030ec4a8c8aea7015f40ef02 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 10eabd62ae7237162a36a333b41c748901a7d888..23eaab1b465b8b88a84cf9f1039621923b640b47 100644 --- a/drivers/net/ovpn/peer.c +++ b/drivers/net/ovpn/peer.c @@ -12,6 +12,8 @@ #include "ovpnpriv.h" #include "bind.h" +#include "pktid.h" +#include "crypto.h" #include "io.h" #include "main.h" #include "netlink.h" @@ -56,6 +58,7 @@ 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);

@@ -94,7 +97,10 @@ 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); call_rcu(&peer->rcu, ovpn_peer_release_rcu); netdev_put(peer->ovpn->dev, &peer->dev_tracker);

} @@ -326,6 +332,29 @@ 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 fef04311c1593db4ccfa3c417487b3d4faaae9d7..a9113a969f94d66fa17208d563d0bbd255c23fa9 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 __rcu *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..2e73d1c1ec8b6c4fe2fc10ebc1a4f3008362df21 --- /dev/null +++ b/drivers/net/ovpn/pktid.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +/* OpenVPN data channel offload

• • Copyright (C) 2020-2025 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 "ovpnpriv.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..0e5fd91d488359f675f500a7368027f7a148f5c6 --- /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) 2020-2025 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;

pktid is 32-bit so atomic_t should be enough (see below).

+};

+/* 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;
  

You may use a 32-bit atomic_t, instead of checking if it equals 0x1_00000000, check if it wraparounds to zero. Additionally, you don't need full memory ordering as you just want an incrementing value:

int seq_num = atomic_fetch_inc_relaxed(&pid->seq_num);

if (unlikely(!seq_num)) ...

• *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 591b97a9925fd9b91f996d6d591fac41b1aa6148..b7322c7c515e5c0744719e11ca81fece3ca28569 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 9db7a9adebdb4cc493f162f89fb2e9c6301fa213..bd3cbcfc770d2c28d234fcdd081b4d02e6496ea0 100644 --- a/drivers/net/ovpn/skb.h +++ b/drivers/net/ovpn/skb.h @@ -20,6 +20,11 @@ struct ovpn_cb { struct ovpn_peer *peer;

• struct ovpn_crypto_key_slot *ks;
• struct aead_request *req;
• struct scatterlist *sg;
• u8 *iv;
• unsigned int payload_offset;

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

-- 2.48.1

-- Qingfang