Re: [PATCH v2 06/25] tcp: authopt: Compute packet signatures

On 11/1/21 16:34, Leonard Crestez wrote: [..]

+static int skb_shash_frags(struct shash_desc *desc,

• 	   struct sk_buff *skb)
  

+{

• struct sk_buff *frag_iter;
• int err, i;
• for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {

• skb_frag_t *f = &skb_shinfo(skb)->frags[i];
  

• u32 p_off, p_len, copied;
  

• struct page *p;
  

• u8 *vaddr;
  

• skb_frag_foreach_page(f, skb_frag_off(f), skb_frag_size(f),
  

• 		      p, p_off, p_len, copied) {
  

• 	vaddr = kmap_atomic(p);
  

• 	err = crypto_shash_update(desc, vaddr + p_off, p_len);
  

• 	kunmap_atomic(vaddr);
  

• 	if (err)
  

• 		return err;
  

• }
  

• }
• skb_walk_frags(skb, frag_iter) {

• err = skb_shash_frags(desc, frag_iter);
  

• if (err)
  

• 	return err;
  

• }
• return 0;

+}

This seems quite sub-optimal: IIUC, shash should only be used for small amount of hashing. That's why tcp-md5 uses ahash with scatterlists. Which drives me to the question: why not reuse tcp_md5sig_pool code?

And it seems that you can avoid TCP_AUTHOPT_ALG_* enum and just supply to crypto the string from socket option (like xfrm does).

Here is my idea: https://lore.kernel.org/all/20211105014953.972946-6-dima@arista.com/T/#u

Thanks, Dmitry