From 519855c508b9a17878c0977a3cdefc09b59b30df Mon Sep 17 00:00:00 2001
From: William Allen Simpson <william.allen.simpson@gmail.com>
Date: Wed, 2 Dec 2009 18:14:19 +0000
Subject: [PATCH] TCPCT part 1c: sysctl_tcp_cookie_size, socket option
TCP_COOKIE_TRANSACTIONS
Define sysctl (tcp_cookie_size) to turn on and off the cookie option
default globally, instead of a compiled configuration option.
Define per socket option (TCP_COOKIE_TRANSACTIONS) for setting constant
data values, retrieving variable cookie values, and other facilities.
Move inline tcp_clear_options() unchanged from net/tcp.h to linux/tcp.h,
near its corresponding struct tcp_options_received (prior to changes).
This is a straightforward re-implementation of an earlier (year-old)
patch that no longer applies cleanly, with permission of the original
author (Adam Langley):
http://thread.gmane.org/gmane.linux.network/102586
These functions will also be used in subsequent patches that implement
additional features.
Requires:
net: TCP_MSS_DEFAULT, TCP_MSS_DESIRED
Signed-off-by: William.Allen.Simpson@gmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
---
Documentation/networking/ip-sysctl.txt | 8 +++++++
include/linux/tcp.h | 33 +++++++++++++++++++++++++-
include/net/tcp.h | 6 +----
net/ipv4/sysctl_net_ipv4.c | 8 +++++++
net/ipv4/tcp_output.c | 3 +++
5 files changed, 52 insertions(+), 6 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 554440af675c..989f5538b8dd 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -164,6 +164,14 @@ tcp_congestion_control - STRING
additional choices may be available based on kernel configuration.
Default is set as part of kernel configuration.
+tcp_cookie_size - INTEGER
+ Default size of TCP Cookie Transactions (TCPCT) option, that may be
+ overridden on a per socket basis by the TCPCT socket option.
+ Values greater than the maximum (16) are interpreted as the maximum.
+ Values greater than zero and less than the minimum (8) are interpreted
+ as the minimum. Odd values are interpreted as the next even value.
+ Default: 0 (off).
+
tcp_dsack - BOOLEAN
Allows TCP to send "duplicate" SACKs.
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 32d7d77b4a01..eaa3113b3786 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -102,7 +102,9 @@ enum {
#define TCP_QUICKACK 12 /* Block/reenable quick acks */
#define TCP_CONGESTION 13 /* Congestion control algorithm */
#define TCP_MD5SIG 14 /* TCP MD5 Signature (RFC2385) */
+#define TCP_COOKIE_TRANSACTIONS 15 /* TCP Cookie Transactions */
+/* for TCP_INFO socket option */
#define TCPI_OPT_TIMESTAMPS 1
#define TCPI_OPT_SACK 2
#define TCPI_OPT_WSCALE 4
@@ -174,6 +176,30 @@ struct tcp_md5sig {
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; /* key (binary) */
};
+/* for TCP_COOKIE_TRANSACTIONS (TCPCT) socket option */
+#define TCP_COOKIE_MIN 8 /* 64-bits */
+#define TCP_COOKIE_MAX 16 /* 128-bits */
+#define TCP_COOKIE_PAIR_SIZE (2*TCP_COOKIE_MAX)
+
+/* Flags for both getsockopt and setsockopt */
+#define TCP_COOKIE_IN_ALWAYS (1 << 0) /* Discard SYN without cookie */
+#define TCP_COOKIE_OUT_NEVER (1 << 1) /* Prohibit outgoing cookies,
+ * supercedes everything. */
+
+/* Flags for getsockopt */
+#define TCP_S_DATA_IN (1 << 2) /* Was data received? */
+#define TCP_S_DATA_OUT (1 << 3) /* Was data sent? */
+
+/* TCP_COOKIE_TRANSACTIONS data */
+struct tcp_cookie_transactions {
+ __u16 tcpct_flags; /* see above */
+ __u8 __tcpct_pad1; /* zero */
+ __u8 tcpct_cookie_desired; /* bytes */
+ __u16 tcpct_s_data_desired; /* bytes of variable data */
+ __u16 tcpct_used; /* bytes in value */
+ __u8 tcpct_value[TCP_MSS_DEFAULT];
+};
+
#ifdef __KERNEL__
#include <linux/skbuff.h>
@@ -227,6 +253,11 @@ struct tcp_options_received {
u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
};
+static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
+{
+ rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
+}
+
/* This is the max number of SACKS that we'll generate and process. It's safe
* to increse this, although since:
* size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
@@ -435,6 +466,6 @@ static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
return (struct tcp_timewait_sock *)sk;
}
-#endif
+#endif /* __KERNEL__ */
#endif /* _LINUX_TCP_H */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4a99a8e39121..738b65f01e26 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -234,6 +234,7 @@ extern int sysctl_tcp_base_mss;
extern int sysctl_tcp_workaround_signed_windows;
extern int sysctl_tcp_slow_start_after_idle;
extern int sysctl_tcp_max_ssthresh;
+extern int sysctl_tcp_cookie_size;
extern atomic_t tcp_memory_allocated;
extern struct percpu_counter tcp_sockets_allocated;
@@ -340,11 +341,6 @@ static inline void tcp_dec_quickack_mode(struct sock *sk,
extern void tcp_enter_quickack_mode(struct sock *sk);
-static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
-{
- rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
-}
-
#define TCP_ECN_OK 1
#define TCP_ECN_QUEUE_CWR 2
#define TCP_ECN_DEMAND_CWR 4
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index c00323bae044..13f7ab6ad6a0 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -712,6 +712,14 @@ static struct ctl_table ipv4_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "tcp_cookie_size",
+ .data = &sysctl_tcp_cookie_size,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
{
.ctl_name = CTL_UNNUMBERED,
.procname = "udp_mem",
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index b8b25049f257..307f318fe931 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -59,6 +59,9 @@ int sysctl_tcp_base_mss __read_mostly = 512;
/* By default, RFC2861 behavior. */
int sysctl_tcp_slow_start_after_idle __read_mostly = 1;
+int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */
+
+
/* Account for new data that has been sent to the network. */
static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb)
{
--
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