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tcp: add server ip to encrypt cookie in fast open

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Encrypt the cookie with both server and client IPv4 addresses,
such that multi-homed server will grant different cookies
based on both the source and destination IPs. No client change
is needed since cookie is opaque to the client.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2013-08-08 14:06:22 -07:00 • committed by David S. Miller
commit 149479d019
3 changed files with 15 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

3
include/net/tcp.h
View file

@ -1300,7 +1300,8 @@ void tcp_free_fastopen_req(struct tcp_sock *tp);
extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
int tcp_fastopen_reset_cipher(void *key, unsigned int len);
void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc);
extern void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
struct tcp_fastopen_cookie *foc);
#define TCP_FASTOPEN_KEY_LENGTH 16

13
net/ipv4/tcp_fastopen.c
View file

@ -58,23 +58,22 @@ error: kfree(ctx);
return err;
}
/* Computes the fastopen cookie for the peer.
* The peer address is a 128 bits long (pad with zeros for IPv4).
/* Computes the fastopen cookie for the IP path.
* The path is a 128 bits long (pad with zeros for IPv4).
*
* The caller must check foc->len to determine if a valid cookie
* has been generated successfully.
*/
void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
void tcp_fastopen_cookie_gen(__be32 src, __be32 dst,
struct tcp_fastopen_cookie *foc)
{
__be32 peer_addr[4] = { addr, 0, 0, 0 };
__be32 path[4] = { src, dst, 0, 0 };
struct tcp_fastopen_context *ctx;
rcu_read_lock();
ctx = rcu_dereference(tcp_fastopen_ctx);
if (ctx) {
crypto_cipher_encrypt_one(ctx->tfm,
foc->val,
(__u8 *)peer_addr);
crypto_cipher_encrypt_one(ctx->tfm, foc->val, (__u8 *)path);
foc->len = TCP_FASTOPEN_COOKIE_SIZE;
}
rcu_read_unlock();

10
net/ipv4/tcp_ipv4.c
View file

@ -1316,9 +1316,11 @@ static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
return true;
}
if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr, valid_foc);
if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
memcmp(&foc->val[0], &valid_foc->val[0],
TCP_FASTOPEN_COOKIE_SIZE) != 0)
@ -1329,14 +1331,16 @@ static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
return true;
} else if (foc->len == 0) { /* Client requesting a cookie */
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr, valid_foc);
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPFASTOPENCOOKIEREQD);
} else {
/* Client sent a cookie with wrong size. Treat it
* the same as invalid and return a valid one.
*/
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr, valid_foc);
}
return false;
}