Karin and Kushina both belonged to Uzumaki Clan.It's a type of Hiden Ninjustu.
Although the name of the jutsu is not mentioned clearly but when I explored more I came to know that:-
Kushina also possessed a powerful and special form of chakra, which made her well-suited for becoming the Nine-Tails' jinchūriki. With her chakra, Kushina was able to materialise chakra chains with which she was able to restrain and subdue the Nine-Tails, both in the real world as well as in her subconscious
1.What is this technique and how does this work
To know more about chakra chains visit here
Known by members of the Uzumaki Clan, this technique moulds the user's chakra into chains which, after materialising, can be used for various purposes such as physically restraining targets, fight them directly or be used as a means of transportation.
Please do visit here too:-Chakra Chains classification
2.Can Naruto use this technique?
Naruto did use this technique during his training under Bee