Commit 7c2ffaf2 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by David S. Miller
Browse files

net/tcp: Calculate TCP-AO traffic keys 



Add traffic key calculation the way it's described in RFC5926.
Wire it up to tcp_finish_connect() and cache the new keys straight away
on already established TCP connections.

Co-developed-by: default avatarFrancesco Ruggeri <fruggeri@arista.com>
Signed-off-by: default avatarFrancesco Ruggeri <fruggeri@arista.com>
Co-developed-by: default avatarSalam Noureddine <noureddine@arista.com>
Signed-off-by: default avatarSalam Noureddine <noureddine@arista.com>
Signed-off-by: default avatarDmitry Safonov <dima@arista.com>
Acked-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0aadc739

include/net/tcp.h

+3 −0
Original line number Diff line number Diff line
@@ -2197,6 +2197,9 @@ struct tcp_sock_af_ops { 
	struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,

					struct sock *addr_sk,

					int sndid, int rcvid);

	int (*ao_calc_key_sk)(struct tcp_ao_key *mkt, u8 *key,

			      const struct sock *sk,

			      __be32 sisn, __be32 disn, bool send);

#endif

};

include/net/tcp_ao.h

+49 −2
Original line number Diff line number Diff line
@@ -89,8 +89,32 @@ struct tcp_ao_info { 
};



#ifdef CONFIG_TCP_AO

/* TCP-AO structures and functions */



struct tcp4_ao_context {

	__be32		saddr;

	__be32		daddr;

	__be16		sport;

	__be16		dport;

	__be32		sisn;

	__be32		disn;

};



struct tcp6_ao_context {

	struct in6_addr	saddr;

	struct in6_addr	daddr;

	__be16		sport;

	__be16		dport;

	__be32		sisn;

	__be32		disn;

};



struct tcp_sigpool;



int tcp_parse_ao(struct sock *sk, int cmd, unsigned short int family,

		 sockptr_t optval, int optlen);

int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,

			    unsigned int len, struct tcp_sigpool *hp);

void tcp_ao_destroy_sock(struct sock *sk);

struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,

				    const union tcp_ao_addr *addr,
@@ -99,11 +123,22 @@ struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, 
int tcp_v4_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);

struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,

				    int sndid, int rcvid);

int tcp_v4_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,

			  const struct sock *sk,

			  __be32 sisn, __be32 disn, bool send);

/* ipv6 specific functions */

int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);

int tcp_v6_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,

			  const struct sock *sk, __be32 sisn,

			  __be32 disn, bool send);

struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,

				    struct sock *addr_sk, int sndid, int rcvid);

#else

int tcp_v6_parse_ao(struct sock *sk, int cmd, sockptr_t optval, int optlen);

void tcp_ao_established(struct sock *sk);

void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb);

void tcp_ao_connect_init(struct sock *sk);



#else /* CONFIG_TCP_AO */



static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk,

		const union tcp_ao_addr *addr, int family, int sndid, int rcvid)

{
@@ -113,6 +148,18 @@ static inline struct tcp_ao_key *tcp_ao_do_lookup(const struct sock *sk, 
static inline void tcp_ao_destroy_sock(struct sock *sk)

{

}



static inline void tcp_ao_established(struct sock *sk)

{

}



static inline void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)

{

}



static inline void tcp_ao_connect_init(struct sock *sk)

{

}

#endif



#endif /* _TCP_AO_H */

net/ipv4/tcp_ao.c

+206 −0
Original line number Diff line number Diff line
@@ -16,6 +16,34 @@ 
#include <net/tcp.h>

#include <net/ipv6.h>



int tcp_ao_calc_traffic_key(struct tcp_ao_key *mkt, u8 *key, void *ctx,

			    unsigned int len, struct tcp_sigpool *hp)

{

	struct scatterlist sg;

	int ret;



	if (crypto_ahash_setkey(crypto_ahash_reqtfm(hp->req),

				mkt->key, mkt->keylen))

		goto clear_hash;



	ret = crypto_ahash_init(hp->req);

	if (ret)

		goto clear_hash;



	sg_init_one(&sg, ctx, len);

	ahash_request_set_crypt(hp->req, &sg, key, len);

	crypto_ahash_update(hp->req);



	ret = crypto_ahash_final(hp->req);

	if (ret)

		goto clear_hash;



	return 0;

clear_hash:

	memset(key, 0, tcp_ao_digest_size(mkt));

	return 1;

}



/* Optimized version of tcp_ao_do_lookup(): only for sockets for which

 * it's known that the keys in ao_info are matching peer's

 * family/address/VRF/etc.
@@ -169,6 +197,71 @@ void tcp_ao_destroy_sock(struct sock *sk) 
	kfree_rcu(ao, rcu);

}



/* 4 tuple and ISNs are expected in NBO */

static int tcp_v4_ao_calc_key(struct tcp_ao_key *mkt, u8 *key,

			      __be32 saddr, __be32 daddr,

			      __be16 sport, __be16 dport,

			      __be32 sisn,  __be32 disn)

{

	/* See RFC5926 3.1.1 */

	struct kdf_input_block {

		u8                      counter;

		u8                      label[6];

		struct tcp4_ao_context	ctx;

		__be16                  outlen;

	} __packed * tmp;

	struct tcp_sigpool hp;

	int err;



	err = tcp_sigpool_start(mkt->tcp_sigpool_id, &hp);

	if (err)

		return err;



	tmp = hp.scratch;

	tmp->counter	= 1;

	memcpy(tmp->label, "TCP-AO", 6);

	tmp->ctx.saddr	= saddr;

	tmp->ctx.daddr	= daddr;

	tmp->ctx.sport	= sport;

	tmp->ctx.dport	= dport;

	tmp->ctx.sisn	= sisn;

	tmp->ctx.disn	= disn;

	tmp->outlen	= htons(tcp_ao_digest_size(mkt) * 8); /* in bits */



	err = tcp_ao_calc_traffic_key(mkt, key, tmp, sizeof(*tmp), &hp);

	tcp_sigpool_end(&hp);



	return err;

}



int tcp_v4_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,

			  const struct sock *sk,

			  __be32 sisn, __be32 disn, bool send)

{

	if (send)

		return tcp_v4_ao_calc_key(mkt, key, sk->sk_rcv_saddr,

					  sk->sk_daddr, htons(sk->sk_num),

					  sk->sk_dport, sisn, disn);

	else

		return tcp_v4_ao_calc_key(mkt, key, sk->sk_daddr,

					  sk->sk_rcv_saddr, sk->sk_dport,

					  htons(sk->sk_num), disn, sisn);

}



static int tcp_ao_calc_key_sk(struct tcp_ao_key *mkt, u8 *key,

			      const struct sock *sk,

			      __be32 sisn, __be32 disn, bool send)

{

	if (mkt->family == AF_INET)

		return tcp_v4_ao_calc_key_sk(mkt, key, sk, sisn, disn, send);

#if IS_ENABLED(CONFIG_IPV6)

	else if (mkt->family == AF_INET6)

		return tcp_v6_ao_calc_key_sk(mkt, key, sk, sisn, disn, send);

#endif

	else

		return -EOPNOTSUPP;

}



struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk,

				    int sndid, int rcvid)

{
@@ -177,6 +270,113 @@ struct tcp_ao_key *tcp_v4_ao_lookup(const struct sock *sk, struct sock *addr_sk, 
	return tcp_ao_do_lookup(sk, addr, AF_INET, sndid, rcvid);

}



static int tcp_ao_cache_traffic_keys(const struct sock *sk,

				     struct tcp_ao_info *ao,

				     struct tcp_ao_key *ao_key)

{

	u8 *traffic_key = snd_other_key(ao_key);

	int ret;



	ret = tcp_ao_calc_key_sk(ao_key, traffic_key, sk,

				 ao->lisn, ao->risn, true);

	if (ret)

		return ret;



	traffic_key = rcv_other_key(ao_key);

	ret = tcp_ao_calc_key_sk(ao_key, traffic_key, sk,

				 ao->lisn, ao->risn, false);

	return ret;

}



void tcp_ao_connect_init(struct sock *sk)

{

	struct tcp_sock *tp = tcp_sk(sk);

	struct tcp_ao_info *ao_info;

	union tcp_ao_addr *addr;

	struct tcp_ao_key *key;

	int family;



	ao_info = rcu_dereference_protected(tp->ao_info,

					    lockdep_sock_is_held(sk));

	if (!ao_info)

		return;



	/* Remove all keys that don't match the peer */

	family = sk->sk_family;

	if (family == AF_INET)

		addr = (union tcp_ao_addr *)&sk->sk_daddr;

#if IS_ENABLED(CONFIG_IPV6)

	else if (family == AF_INET6)

		addr = (union tcp_ao_addr *)&sk->sk_v6_daddr;

#endif

	else

		return;



	hlist_for_each_entry_rcu(key, &ao_info->head, node) {

		if (!tcp_ao_key_cmp(key, addr, key->prefixlen, family, -1, -1))

			continue;



		if (key == ao_info->current_key)

			ao_info->current_key = NULL;

		if (key == ao_info->rnext_key)

			ao_info->rnext_key = NULL;

		hlist_del_rcu(&key->node);

		atomic_sub(tcp_ao_sizeof_key(key), &sk->sk_omem_alloc);

		call_rcu(&key->rcu, tcp_ao_key_free_rcu);

	}



	key = tp->af_specific->ao_lookup(sk, sk, -1, -1);

	if (key) {

		/* if current_key or rnext_key were not provided,

		 * use the first key matching the peer

		 */

		if (!ao_info->current_key)

			ao_info->current_key = key;

		if (!ao_info->rnext_key)

			ao_info->rnext_key = key;

		tp->tcp_header_len += tcp_ao_len(key);



		ao_info->lisn = htonl(tp->write_seq);

	} else {

		/* Can't happen: tcp_connect() verifies that there's

		 * at least one tcp-ao key that matches the remote peer.

		 */

		WARN_ON_ONCE(1);

		rcu_assign_pointer(tp->ao_info, NULL);

		kfree(ao_info);

	}

}



void tcp_ao_established(struct sock *sk)

{

	struct tcp_ao_info *ao;

	struct tcp_ao_key *key;



	ao = rcu_dereference_protected(tcp_sk(sk)->ao_info,

				       lockdep_sock_is_held(sk));

	if (!ao)

		return;



	hlist_for_each_entry_rcu(key, &ao->head, node)

		tcp_ao_cache_traffic_keys(sk, ao, key);

}



void tcp_ao_finish_connect(struct sock *sk, struct sk_buff *skb)

{

	struct tcp_ao_info *ao;

	struct tcp_ao_key *key;



	ao = rcu_dereference_protected(tcp_sk(sk)->ao_info,

				       lockdep_sock_is_held(sk));

	if (!ao)

		return;



	WRITE_ONCE(ao->risn, tcp_hdr(skb)->seq);



	hlist_for_each_entry_rcu(key, &ao->head, node)

		tcp_ao_cache_traffic_keys(sk, ao, key);

}



static bool tcp_ao_can_set_current_rnext(struct sock *sk)

{

	/* There aren't current/rnext keys on TCP_LISTEN sockets */
@@ -558,6 +758,12 @@ static int tcp_ao_add_cmd(struct sock *sk, unsigned short int family, 
	if (ret < 0)

		goto err_free_sock;



	/* Change this condition if we allow adding keys in states

	 * like close_wait, syn_sent or fin_wait...

	 */

	if (sk->sk_state == TCP_ESTABLISHED)

		tcp_ao_cache_traffic_keys(sk, ao_info, key);



	tcp_ao_link_mkt(ao_info, key);

	if (first) {

		sk_gso_disable(sk);

net/ipv4/tcp_input.c

+2 −0
Original line number Diff line number Diff line
@@ -6151,6 +6151,7 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb) 
	struct tcp_sock *tp = tcp_sk(sk);

	struct inet_connection_sock *icsk = inet_csk(sk);



	tcp_ao_finish_connect(sk, skb);

	tcp_set_state(sk, TCP_ESTABLISHED);

	icsk->icsk_ack.lrcvtime = tcp_jiffies32;
@@ -6648,6 +6649,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb) 
					  skb);

			WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);

		}

		tcp_ao_established(sk);

		smp_mb();

		tcp_set_state(sk, TCP_ESTABLISHED);

		sk->sk_state_change(sk);

net/ipv4/tcp_ipv4.c

+1 −0
Original line number Diff line number Diff line
@@ -2288,6 +2288,7 @@ static const struct tcp_sock_af_ops tcp_sock_ipv4_specific = { 
#ifdef CONFIG_TCP_AO

	.ao_lookup		= tcp_v4_ao_lookup,

	.ao_parse		= tcp_v4_parse_ao,

	.ao_calc_key_sk		= tcp_v4_ao_calc_key_sk,

#endif

};

#endif