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 (local)

Thanks,
          Dmitry