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tcp: socket option to set TCP fast open key

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New socket option TCP_FASTOPEN_KEY to allow different keys per
listener.  The listener by default uses the global key until the
socket option is set.  The key is a 16 bytes long binary data. This
option has no effect on regular non-listener TCP sockets.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2017-10-18 11:22:51 -07:00 committed by David S. Miller
parent ce12f7ddff
commit 1fba70e5b6
7 changed files with 82 additions and 19 deletions
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2
include/net/request_sock.h
View File

@ -150,6 +150,8 @@ struct fastopen_queue {
spinlock_t lock;
int qlen; /* # of pending (TCP_SYN_RECV) reqs */
int max_qlen; /* != 0 iff TFO is currently enabled */
struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
};
/** struct request_sock_queue - queue of request_socks

5
include/net/tcp.h
View File

@ -1555,9 +1555,10 @@ struct tcp_fastopen_request {
int copied; /* queued in tcp_connect() */
};
void tcp_free_fastopen_req(struct tcp_sock *tp);
void tcp_fastopen_destroy_cipher(struct sock *sk);
void tcp_fastopen_ctx_destroy(struct net *net);
int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len);
int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
void *key, unsigned int len);
void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,

1
include/uapi/linux/tcp.h
View File

@ -119,6 +119,7 @@ enum {
#define TCP_FASTOPEN_CONNECT 30 /* Attempt FastOpen with connect */
#define TCP_ULP 31 /* Attach a ULP to a TCP connection */
#define TCP_MD5SIG_EXT 32 /* TCP MD5 Signature with extensions */
#define TCP_FASTOPEN_KEY 33 /* Set the key for Fast Open (cookie) */
struct tcp_repair_opt {
__u32 opt_code;

3
net/ipv4/sysctl_net_ipv4.c
View File

@ -284,7 +284,8 @@ static int proc_tcp_fastopen_key(struct ctl_table *table, int write,
ret = -EINVAL;
goto bad_key;
}
tcp_fastopen_reset_cipher(net, user_key, TCP_FASTOPEN_KEY_LENGTH);
tcp_fastopen_reset_cipher(net, NULL, user_key,
TCP_FASTOPEN_KEY_LENGTH);
}
bad_key:

33
net/ipv4/tcp.c
View File

@ -2571,6 +2571,17 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
release_sock(sk);
return err;
}
case TCP_FASTOPEN_KEY: {
__u8 key[TCP_FASTOPEN_KEY_LENGTH];
if (optlen != sizeof(key))
return -EINVAL;
if (copy_from_user(key, optval, optlen))
return -EFAULT;
return tcp_fastopen_reset_cipher(net, sk, key, sizeof(key));
}
default:
/* fallthru */
break;
@ -3157,6 +3168,28 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
return -EFAULT;
return 0;
case TCP_FASTOPEN_KEY: {
__u8 key[TCP_FASTOPEN_KEY_LENGTH];
struct tcp_fastopen_context *ctx;
if (get_user(len, optlen))
return -EFAULT;
rcu_read_lock();
ctx = rcu_dereference(icsk->icsk_accept_queue.fastopenq.ctx);
if (ctx)
memcpy(key, ctx->key, sizeof(key));
else
len = 0;
rcu_read_unlock();
len = min_t(unsigned int, len, sizeof(key));
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, key, len))
return -EFAULT;
return 0;
}
case TCP_THIN_LINEAR_TIMEOUTS:
val = tp->thin_lto;
break;

56
net/ipv4/tcp_fastopen.c
View File

@ -29,7 +29,7 @@ void tcp_fastopen_init_key_once(struct net *net)
* for a valid cookie, so this is an acceptable risk.
*/
get_random_bytes(key, sizeof(key));
tcp_fastopen_reset_cipher(net, key, sizeof(key));
tcp_fastopen_reset_cipher(net, NULL, key, sizeof(key));
}
static void tcp_fastopen_ctx_free(struct rcu_head *head)
@ -40,6 +40,16 @@ static void tcp_fastopen_ctx_free(struct rcu_head *head)
kfree(ctx);
}
void tcp_fastopen_destroy_cipher(struct sock *sk)
{
struct tcp_fastopen_context *ctx;
ctx = rcu_dereference_protected(
inet_csk(sk)->icsk_accept_queue.fastopenq.ctx, 1);
if (ctx)
call_rcu(&ctx->rcu, tcp_fastopen_ctx_free);
}
void tcp_fastopen_ctx_destroy(struct net *net)
{
struct tcp_fastopen_context *ctxt;
@ -55,10 +65,12 @@ void tcp_fastopen_ctx_destroy(struct net *net)
call_rcu(&ctxt->rcu, tcp_fastopen_ctx_free);
}
int tcp_fastopen_reset_cipher(struct net *net, void *key, unsigned int len)
int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
void *key, unsigned int len)
{
int err;
struct tcp_fastopen_context *ctx, *octx;
struct fastopen_queue *q;
int err;
ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
if (!ctx)
@ -79,27 +91,39 @@ error: kfree(ctx);
}
memcpy(ctx->key, key, len);
spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
if (sk) {
q = &inet_csk(sk)->icsk_accept_queue.fastopenq;
spin_lock_bh(&q->lock);
octx = rcu_dereference_protected(q->ctx,
lockdep_is_held(&q->lock));
rcu_assign_pointer(q->ctx, ctx);
spin_unlock_bh(&q->lock);
} else {
spin_lock(&net->ipv4.tcp_fastopen_ctx_lock);
octx = rcu_dereference_protected(net->ipv4.tcp_fastopen_ctx,
lockdep_is_held(&net->ipv4.tcp_fastopen_ctx_lock));
rcu_assign_pointer(net->ipv4.tcp_fastopen_ctx, ctx);
spin_unlock(&net->ipv4.tcp_fastopen_ctx_lock);
}
if (octx)
call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
return err;
}
static bool __tcp_fastopen_cookie_gen(struct net *net,
const void *path,
static bool __tcp_fastopen_cookie_gen(struct sock *sk, const void *path,
struct tcp_fastopen_cookie *foc)
{
struct tcp_fastopen_context *ctx;
bool ok = false;
rcu_read_lock();
ctx = rcu_dereference(net->ipv4.tcp_fastopen_ctx);
ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
if (!ctx)
ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
if (ctx) {
crypto_cipher_encrypt_one(ctx->tfm, foc->val, path);
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
@ -115,7 +139,7 @@ static bool __tcp_fastopen_cookie_gen(struct net *net,
*
* XXX (TFO) - refactor when TCP_FASTOPEN_COOKIE_SIZE != AES_BLOCK_SIZE.
*/
static bool tcp_fastopen_cookie_gen(struct net *net,
static bool tcp_fastopen_cookie_gen(struct sock *sk,
struct request_sock *req,
struct sk_buff *syn,
struct tcp_fastopen_cookie *foc)
@ -124,7 +148,7 @@ static bool tcp_fastopen_cookie_gen(struct net *net,
const struct iphdr *iph = ip_hdr(syn);
__be32 path[4] = { iph->saddr, iph->daddr, 0, 0 };
return __tcp_fastopen_cookie_gen(net, path, foc);
return __tcp_fastopen_cookie_gen(sk, path, foc);
}
#if IS_ENABLED(CONFIG_IPV6)
@ -132,13 +156,13 @@ static bool tcp_fastopen_cookie_gen(struct net *net,
const struct ipv6hdr *ip6h = ipv6_hdr(syn);
struct tcp_fastopen_cookie tmp;
if (__tcp_fastopen_cookie_gen(net, &ip6h->saddr, &tmp)) {
if (__tcp_fastopen_cookie_gen(sk, &ip6h->saddr, &tmp)) {
struct in6_addr *buf = &tmp.addr;
int i;
for (i = 0; i < 4; i++)
buf->s6_addr32[i] ^= ip6h->daddr.s6_addr32[i];
return __tcp_fastopen_cookie_gen(net, buf, foc);
return __tcp_fastopen_cookie_gen(sk, buf, foc);
}
}
#endif
@ -313,7 +337,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
goto fastopen;
if (foc->len >= 0 && /* Client presents or requests a cookie */
tcp_fastopen_cookie_gen(sock_net(sk), req, skb, &valid_foc) &&
tcp_fastopen_cookie_gen(sk, req, skb, &valid_foc) &&
foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
foc->len == valid_foc.len &&
!memcmp(foc->val, valid_foc.val, foc->len)) {

1
net/ipv4/tcp_ipv4.c
View File

@ -1893,6 +1893,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
/* If socket is aborted during connect operation */
tcp_free_fastopen_req(tp);
tcp_fastopen_destroy_cipher(sk);
tcp_saved_syn_free(tp);
sk_sockets_allocated_dec(sk);