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

Antonio Quartulli
2025-02-07T13:12:32Z

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:
>> +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.
>
> [...]
>> + /* 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
>
>
>> + 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.