linux/net/ipv6/tcp_ao.c
Dmitry Safonov 248411b8cb net/tcp: Wire up l3index to TCP-AO
Similarly how TCP_MD5SIG_FLAG_IFINDEX works for TCP-MD5,
TCP_AO_KEYF_IFINDEX is an AO-key flag that binds that MKT to a specified
by L3 ifinndex. Similarly, without this flag the key will work in
the default VRF l3index = 0 for connections.
To prevent AO-keys from overlapping, it's restricted to add key B for a
socket that has key A, which have the same sndid/rcvid and one of
the following is true:
- !(A.keyflags & TCP_AO_KEYF_IFINDEX) or !(B.keyflags & TCP_AO_KEYF_IFINDEX)
  so that any key is non-bound to a VRF
- A.l3index == B.l3index
  both want to work for the same VRF

Additionally, it's restricted to match TCP-MD5 keys for the same peer
the following way:
|--------------|--------------------|----------------|---------------|
|              | MD5 key without    |     MD5 key    |    MD5 key    |
|              |     l3index        |    l3index=0   |   l3index=N   |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  without     |       reject       |    reject      |   reject      |
|  l3index     |                    |                |               |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  l3index=0   |       reject       |    reject      |   allow       |
|--------------|--------------------|----------------|---------------|
|  TCP-AO key  |                    |                |               |
|  l3index=N   |       reject       |    allow       |   reject      |
|--------------|--------------------|----------------|---------------|

This is done with the help of tcp_md5_do_lookup_any_l3index() to reject
adding AO key without TCP_AO_KEYF_IFINDEX if there's TCP-MD5 in any VRF.
This is important for case where sysctl_tcp_l3mdev_accept = 1
Similarly, for TCP-AO lookups tcp_ao_do_lookup() may be used with
l3index < 0, so that __tcp_ao_key_cmp() will match TCP-AO key in any VRF.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-10-27 10:35:46 +01:00

169 lines
4.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* INET An implementation of the TCP Authentication Option (TCP-AO).
* See RFC5925.
*
* Authors: Dmitry Safonov <dima@arista.com>
* Francesco Ruggeri <fruggeri@arista.com>
* Salam Noureddine <noureddine@arista.com>
*/
#include <crypto/hash.h>
#include <linux/tcp.h>
#include <net/tcp.h>
#include <net/ipv6.h>
static int tcp_v6_ao_calc_key(struct tcp_ao_key *mkt, u8 *key,
const struct in6_addr *saddr,
const struct in6_addr *daddr,
__be16 sport, __be16 dport,
__be32 sisn, __be32 disn)
{
struct kdf_input_block {
u8 counter;
u8 label[6];
struct tcp6_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_v6_ao_calc_key_skb(struct tcp_ao_key *mkt, u8 *key,
const struct sk_buff *skb,
__be32 sisn, __be32 disn)
{
const struct ipv6hdr *iph = ipv6_hdr(skb);
const struct tcphdr *th = tcp_hdr(skb);
return tcp_v6_ao_calc_key(mkt, key, &iph->saddr,
&iph->daddr, th->source,
th->dest, sisn, disn);
}
int tcp_v6_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_v6_ao_calc_key(mkt, key, &sk->sk_v6_rcv_saddr,
&sk->sk_v6_daddr, htons(sk->sk_num),
sk->sk_dport, sisn, disn);
else
return tcp_v6_ao_calc_key(mkt, key, &sk->sk_v6_daddr,
&sk->sk_v6_rcv_saddr, sk->sk_dport,
htons(sk->sk_num), disn, sisn);
}
int tcp_v6_ao_calc_key_rsk(struct tcp_ao_key *mkt, u8 *key,
struct request_sock *req)
{
struct inet_request_sock *ireq = inet_rsk(req);
return tcp_v6_ao_calc_key(mkt, key,
&ireq->ir_v6_loc_addr, &ireq->ir_v6_rmt_addr,
htons(ireq->ir_num), ireq->ir_rmt_port,
htonl(tcp_rsk(req)->snt_isn),
htonl(tcp_rsk(req)->rcv_isn));
}
struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
struct sock *addr_sk,
int sndid, int rcvid)
{
int l3index = l3mdev_master_ifindex_by_index(sock_net(sk),
addr_sk->sk_bound_dev_if);
struct in6_addr *addr = &addr_sk->sk_v6_daddr;
return tcp_ao_do_lookup(sk, l3index, (union tcp_ao_addr *)addr,
AF_INET6, sndid, rcvid);
}
struct tcp_ao_key *tcp_v6_ao_lookup_rsk(const struct sock *sk,
struct request_sock *req,
int sndid, int rcvid)
{
struct inet_request_sock *ireq = inet_rsk(req);
struct in6_addr *addr = &ireq->ir_v6_rmt_addr;
int l3index;
l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);
return tcp_ao_do_lookup(sk, l3index, (union tcp_ao_addr *)addr,
AF_INET6, sndid, rcvid);
}
int tcp_v6_ao_hash_pseudoheader(struct tcp_sigpool *hp,
const struct in6_addr *daddr,
const struct in6_addr *saddr, int nbytes)
{
struct tcp6_pseudohdr *bp;
struct scatterlist sg;
bp = hp->scratch;
/* 1. TCP pseudo-header (RFC2460) */
bp->saddr = *saddr;
bp->daddr = *daddr;
bp->len = cpu_to_be32(nbytes);
bp->protocol = cpu_to_be32(IPPROTO_TCP);
sg_init_one(&sg, bp, sizeof(*bp));
ahash_request_set_crypt(hp->req, &sg, NULL, sizeof(*bp));
return crypto_ahash_update(hp->req);
}
int tcp_v6_ao_hash_skb(char *ao_hash, struct tcp_ao_key *key,
const struct sock *sk, const struct sk_buff *skb,
const u8 *tkey, int hash_offset, u32 sne)
{
return tcp_ao_hash_skb(AF_INET6, ao_hash, key, sk, skb, tkey,
hash_offset, sne);
}
int tcp_v6_parse_ao(struct sock *sk, int cmd,
sockptr_t optval, int optlen)
{
return tcp_parse_ao(sk, cmd, AF_INET6, optval, optlen);
}
int tcp_v6_ao_synack_hash(char *ao_hash, struct tcp_ao_key *ao_key,
struct request_sock *req, const struct sk_buff *skb,
int hash_offset, u32 sne)
{
void *hash_buf = NULL;
int err;
hash_buf = kmalloc(tcp_ao_digest_size(ao_key), GFP_ATOMIC);
if (!hash_buf)
return -ENOMEM;
err = tcp_v6_ao_calc_key_rsk(ao_key, hash_buf, req);
if (err)
goto out;
err = tcp_ao_hash_skb(AF_INET6, ao_hash, ao_key, req_to_sk(req), skb,
hash_buf, hash_offset, sne);
out:
kfree(hash_buf);
return err;
}