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

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Message-ID: <3dca88d7-7037-4721-aae7-35970e97be21@openvpn.net>
Date: Fri, 7 Feb 2025 14:13:40 +0100
From: Antonio Quartulli <antonio@...nvpn.net>
To: Sabrina Dubroca <sd@...asysnail.net>
Cc: netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Donald Hunter <donald.hunter@...il.com>, Shuah Khan <shuah@...nel.org>,
 ryazanov.s.a@...il.com, Andrew Lunn <andrew+netdev@...n.ch>,
 Simon Horman <horms@...nel.org>, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, Xiao Liang <shaw.leon@...il.com>
Subject: 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:
>> +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.