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

On 05/02/2025 22:50, Sabrina Dubroca wrote:

Hi Antonio,

Another one I should have spotted a long time ago :(

better late than never (I think..)

2025-01-13, 10:31:28 +0100, Antonio Quartulli wrote:

quoted

+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];

You'll have to kmalloc this as well, it gets passed to the crypto API
and with async crypto, it'll be used after ovpn_aead_encrypt has
returned.

[...]

quoted

+	/* 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);

                                                                         ^^
passed here

quoted

+	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];

And same here.

(maybe something for the todolist: ovpn could copy the alloc trick
from esp_alloc_tmp, like I did for macsec_alloc_req -- not required,
but could be nice to avoid many small allocs and all their failure
checks)

Ouch, you're right. I will pre-allocate iv as well, like I do for sg.

And thanks for the hints, I'll add that to my todo.

Cheers,


-- 
Antonio Quartulli
OpenVPN Inc.