TCPCT API update for 2.6.37
Subsystems (3)
With the recent flurry of messages related to TCPCT, I devoted a nice snowy Saturday afternoon to updating the socket option code. Linux is rather fair behind on TCPCT implementation, so this will help with future software compatibility.
I'm not on this list, so anybody with comments should CC me. Thanks.
PATCH 1/1 TCPCT socket API update to draft -02
Use most recently specified symbols of RFC-to-be-6013.
Permit setting either cookie or s_data or both (sequentially).
Allows different s_data limits for SYN and SYN_ACK.
Split the data value from socket option header, saving more than 1K of stack space in the handler by copying long data values directly from user space into the kref block.
Signed-off-by [email protected]
--- include/linux/tcp.h | 35 ++++++++++++++++----- net/ipv4/tcp.c | 86 ++++++++++++++++++++++++++++++++++++-------------- 2 files changed, 89 insertions(+), 32 deletions(-)
include/linux/tcp.h +29 -10
@@ -184,23 +184,42 @@ struct tcp_md5sig {#define TCP_COOKIE_MAX 16/* 128-bits */ #define TCP_COOKIE_PAIR_SIZE (2*TCP_COOKIE_MAX) +/* Implementation-specific data limits */ +#define TCP_SYN_DATA_LIMIT (TCP_MSS_DEFAULT - sizeof(struct tcphdr)) +#define TCP_SYN_ACK_DATA_LIMIT (TCP_MSS_DESIRED) +/* 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, +#define TCPCT_IN_ALWAYS (1 << 0)/* Discard SYN without cookie */ +#define TCPCT_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 */ +#define TCPCT_IN_DATA (1 << 2)/* Was data received? */ +#define TCPCT_OUT_DATA (1 << 3)/* Was data sent? */ +/* reserved for future use: bits 4 .. 6 */ +#define TCPCT_EXTEND (1 << 7) + +/* Extended Option flags for both getsockopt and setsockopt */ +#define TCPCT_EXTEND_SIZE (0x7)/* mask */ +#define TCPCT_EXTEND_TS32 (0x1)/* default */ +#define TCPCT_EXTEND_TS64 (0x2) +#define TCPCT_EXTEND_TS128 (0x4) + +/* TCP_COOKIE_TRANSACTIONS socket option header */ struct tcp_cookie_transactions {__u16 tcpct_flags;/* see above */ -__u8 __tcpct_pad1;/* zero */ +__u8 tcpct_extended;__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 ]; +}; + +struct tcpct_full { +struct tcp_cookie_transactions soh; +__u8 tcpct_value[TCP_COOKIE_PAIR_SIZE ]; +}; + +struct tcpct_half { +struct tcp_cookie_transactions soh; +__u8 tcpct_value[TCP_COOKIE_MAX ]; };#ifdef __KERNEL__
net/ipv4/tcp.c +62 -24
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1.7.1
PATCH 1/1 TCPCT sysctl API update to draft -02
In reply to William Allen SimpsonCirca 15 months ago, my first submitted patch was a sysctl, and there was a conflict that appeared in a later merge of trees. Experts, am I in the right ballpark this time around?
Later, I'll submit the manpage patch to [email protected] too.
===
Use most recently specified symbols of RFC-to-be-6013.
Allows different global s_data limits for SYN and SYN_ACK.
Signed-off-by [email protected]
--- include/net/tcp.h | 2 ++ net/ipv4/sysctl_net_ipv4.c | 25 ++++++++++++++++++++++++- net/ipv4/tcp_output.c | 19 +++++++++++++++++-- 3 files changed, 43 insertions(+), 3 deletions(-)
include/net/tcp.h +2 -0
@@ -241,6 +241,8 @@ 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 int sysctl_tcp_syn_data_limit; +extern int sysctl_tcp_syn_ack_data_limit;extern int sysctl_tcp_thin_linear_timeouts;extern int sysctl_tcp_thin_dupack;
net/ipv4/sysctl_net_ipv4.c +24 -1
@@ -30,6 +30,9 @@ static int tcp_adv_win_scale_min = -31;static int tcp_adv_win_scale_max =31 ;static int ip_ttl_min =1 ;static int ip_ttl_max =255 ; +static int tcp_cookie_max =TCP_COOKIE_MAX ; +static int tcp_syn_data_max =TCP_MSS_DEFAULT -40 ; +static int tcp_syn_ack_data_max =TCP_MSS_DESIRED ;/* Update system visible IP port range */ static void set_local_port_range (int range[2 ])
@@ -588,7 +591,27 @@ static struct ctl_table ipv4_table[] = { .data = &sysctl_tcp_cookie_size, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &tcp_cookie_max, + }, + { + .procname = "tcp_syn_data_limit", + .data = &sysctl_tcp_syn_data_limit, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &tcp_syn_data_max, + }, + { + .procname = "tcp_syn_ack_data_limit", + .data = &sysctl_tcp_syn_ack_data_limit, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &tcp_syn_ack_data_max, }, { .procname = "tcp_thin_linear_timeouts",
net/ipv4/tcp_output.c +17 -2
@@ -63,6 +63,15 @@ int sysctl_tcp_slow_start_after_idle __read_mostly = 1;int sysctl_tcp_cookie_size__read_mostly =0 ;/* TCP_COOKIE_MAX */ EXPORT_SYMBOL_GPL (sysctl_tcp_cookie_size); +int sysctl_tcp_syn_data_limit__read_mostly =TCP_MSS_DEFAULT -40 ; +EXPORT_SYMBOL_GPL (sysctl_tcp_syn_data_limit); + +/* As a matter of security policy, keep the initial setting small for most +* client systems to avoid their use in amplification DoS attacks. +*/ +int sysctl_tcp_syn_ack_data_limit__read_mostly =80 ;/* TCP_MSS_DESIRED */ +EXPORT_SYMBOL_GPL (sysctl_tcp_syn_ack_data_limit); +/* 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)
@@ -2418,10 +2427,16 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,struct tcp_md5sig_key *md5;int tcp_header_size;int mss; -int s_data_desired =0 ; +int s_data_desired; -if (cvp !=NULL && cvp->s_data_constant && cvp->s_data_desired) +if (cvp !=NULL && + cvp->s_data_constant && + cvp->s_data_desired >0 && + cvp->s_data_desired <= sysctl_tcp_syn_ack_data_limit) s_data_desired = cvp->s_data_desired; +else + s_data_desired =0 ; + skb =sock_wmalloc (sk,MAX_TCP_HEADER +15 + s_data_desired,1 ,GFP_ATOMIC );if (skb ==NULL )return NULL ;
Signature · 1 line
1.7.1