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tcp: simplify fast open cookie processing 

Consolidate various cookie checking and generation code to simplify
the fast open processing. The main goal is to reduce code duplication
in tcp_v4_conn_request() for IPv6 support.

Removes two experimental sysctl flags TFO_SERVER_ALWAYS and
TFO_SERVER_COOKIE_NOT_CHKD used primarily for developmental debugging
purposes.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Signed-off-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 2014-05-11 20:22:10 -07:00 committed by David S. Miller
parent 5b7ed0892f
commit 89278c9dc9
5 changed files with 33 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/tcp.h
View File

@ -366,11 +366,6 @@ static inline bool tcp_passive_fastopen(const struct sock *sk)
tcp_sk(sk)->fastopen_rsk != NULL);
}
static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
{
return foc->len != -1;
}
extern void tcp_sock_destruct(struct sock *sk);
static inline int fastopen_init_queue(struct sock *sk, int backlog)

9
include/net/tcp.h
View File

@ -220,8 +220,6 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define TFO_SERVER_ENABLE 2
#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
/* Process SYN data but skip cookie validation */
#define TFO_SERVER_COOKIE_NOT_CHKED 0x100
/* Accept SYN data w/o any cookie option */
#define TFO_SERVER_COOKIE_NOT_REQD 0x200
@ -230,10 +228,6 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
*/
#define TFO_SERVER_WO_SOCKOPT1 0x400
#define TFO_SERVER_WO_SOCKOPT2 0x800
/* Always create TFO child sockets on a TFO listener even when
* cookie/data not present. (For testing purpose!)
*/
#define TFO_SERVER_ALWAYS 0x1000
extern struct inet_timewait_death_row tcp_death_row;
@ -1335,8 +1329,7 @@ int tcp_fastopen_create_child(struct sock *sk,
struct request_sock *req);
bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct tcp_fastopen_cookie *foc,
struct tcp_fastopen_cookie *valid_foc);
struct tcp_fastopen_cookie *foc);
void tcp_fastopen_init_key_once(bool publish);
#define TCP_FASTOPEN_KEY_LENGTH 16

71
net/ipv4/tcp_fastopen.c
View File

@ -228,59 +228,44 @@ static bool tcp_fastopen_queue_check(struct sock *sk)
return true;
}
/* Returns true if we should perform Fast Open on the SYN. The cookie (foc)
* may be updated and return the client in the SYN-ACK later. E.g., Fast Open
* cookie request (foc->len == 0).
*/
bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
struct request_sock *req,
struct tcp_fastopen_cookie *foc,
struct tcp_fastopen_cookie *valid_foc)
struct tcp_fastopen_cookie *foc)
{
bool skip_cookie = false;
struct tcp_fastopen_cookie valid_foc = { .len = -1 };
bool syn_data = TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1;
if (likely(!fastopen_cookie_present(foc))) {
/* See include/net/tcp.h for the meaning of these knobs */
if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
(TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
skip_cookie = true; /* no cookie to validate */
else
return false;
}
/* A FO option is present; bump the counter. */
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
!tcp_fastopen_queue_check(sk))
if (!((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) &&
(syn_data || foc->len >= 0) &&
tcp_fastopen_queue_check(sk))) {
foc->len = -1;
return false;
}
if (skip_cookie) {
if (syn_data && (sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD))
goto fastopen;
tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr, &valid_foc);
if (foc->len == TCP_FASTOPEN_COOKIE_SIZE &&
foc->len == valid_foc.len &&
!memcmp(foc->val, valid_foc.val, foc->len)) {
fastopen:
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
foc->len = -1;
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
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,
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)
return false;
valid_foc->len = -1;
}
/* Acknowledge the data received from the peer. */
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,
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,
ip_hdr(skb)->daddr, valid_foc);
}
NET_INC_STATS_BH(sock_net(sk), foc->len ?
LINUX_MIB_TCPFASTOPENPASSIVEFAIL :
LINUX_MIB_TCPFASTOPENCOOKIEREQD);
*foc = valid_foc;
return false;
}
EXPORT_SYMBOL(tcp_fastopen_check);

10
net/ipv4/tcp_ipv4.c
View File

@ -1273,7 +1273,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
bool want_cookie = false;
struct flowi4 fl4;
struct tcp_fastopen_cookie foc = { .len = -1 };
struct tcp_fastopen_cookie valid_foc = { .len = -1 };
struct sk_buff *skb_synack;
int do_fastopen;
@ -1381,7 +1380,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
if (dst == NULL)
goto drop_and_free;
}
do_fastopen = tcp_fastopen_check(sk, skb, req, &foc, &valid_foc);
do_fastopen = !want_cookie &&
tcp_fastopen_check(sk, skb, req, &foc);
/* We don't call tcp_v4_send_synack() directly because we need
* to make sure a child socket can be created successfully before
@ -1394,8 +1394,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
* latter to remove its dependency on the current implementation
* of tcp_v4_send_synack()->tcp_select_initial_window().
*/
skb_synack = tcp_make_synack(sk, dst, req,
fastopen_cookie_present(&valid_foc) ? &valid_foc : NULL);
skb_synack = tcp_make_synack(sk, dst, req, &foc);
if (skb_synack) {
__tcp_v4_send_check(skb_synack, ireq->ir_loc_addr, ireq->ir_rmt_addr);
@ -1415,9 +1414,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
tcp_rsk(req)->listener = NULL;
/* Add the request_sock to the SYN table */
inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
if (fastopen_cookie_present(&foc) && foc.len != 0)
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
} else if (tcp_fastopen_create_child(sk, skb, skb_synack, req))
goto drop_and_release;

2
net/ipv4/tcp_output.c
View File

@ -627,7 +627,7 @@ static unsigned int tcp_synack_options(struct sock *sk,
if (unlikely(!ireq->tstamp_ok))
remaining -= TCPOLEN_SACKPERM_ALIGNED;
}
if (foc != NULL) {
if (foc != NULL && foc->len >= 0) {
u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
need = (need + 3) & ~3U; /* Align to 32 bits */
if (remaining >= need) {