TCPCT part 1a: extend struct tcp_request_sock
Subsystems (3)
PATCH 1/4 TCPCT part 1a: extend struct tcp_request_sock
Pass additional parameters associated with sending SYNACK. This is not as straightforward or architecturally clean as previously proposed, and has the unfortunate side effect of potentially including otherwise unneeded headers for related protocols, but that problem will affect very few files.
--- include/net/extend_request_sock.h | 37 +++++++++++++++++++++++++++++++++++++ 1 files changed, 37 insertions(+), 0 deletions(-) create mode 100644 include/net/extend_request_sock.h
include/net/extend_request_sock.h new file +37 -0
@@ -0,0 +1,37 @@ +#ifndef _EXTEND_REQUEST_SOCK_H +#define _EXTEND_REQUEST_SOCK_H +/* +* Short term extension of struct tcp_request_sock and related. +* +* Copyright (C) 2009 [email protected] +* All rights reserved. +* +* This program is free software; you can redistribute it and/or +* modify it under the terms of the GNU General Public License +* as published by the Free Software Foundation; either version +* 2 of the License, or (at your option) any later version. +*/ +#include <linux/tcp.h> +#if defined(CONFIG_IPV6 ) || defined (CONFIG_IPV6_MODULE ) +#include <linux/ipv6.h> +#endif + +struct extend_request_sock { +union { +struct tcp_request_sock tcp4rsk; +#if defined(CONFIG_IPV6 ) || defined (CONFIG_IPV6_MODULE ) +struct tcp6_request_sock tcp6rsk; +#endif + } header; + +u8 cookie_plus; +u8 cookie_in_always:1 , + cookie_out_never:1 ; +}; + +static inline struct extend_request_sock *ext_rsk (const struct request_sock *req) +{ +return (struct extend_request_sock *)req; +} + +#endif /* _EXTEND_REQUEST_SOCK_H */
Signature · 1 line
1.6.0.4
Quoted 11 lines · William Allen Simpson
Pass additional parameters associated with sending SYNACK. This is not as straightforward or architecturally clean as previously proposed, and has the unfortunate side effect of potentially including otherwise unneeded headers for related protocols, but that problem will affect very few files.
--- include/net/extend_request_sock.h | 37 +++++++++++++++++++++++++++++++++++++ 1 files changed, 37 insertions(+), 0 deletions(-) create mode 100644 include/net/extend_request_sock.h
This technique appears to be unworkable:
net/ipv4/tcp_ipv4.c +10 -0
@@ -71,6 +71,7 @@#include <net/timewait_sock.h> #include <net/xfrm.h> #include <net/netdma.h> +#include <net/extend_request_sock.h> #include <linux/inet.h> #include <linux/ipv6.h>
@@ -1195,6 +1196,15 @@ struct request_sock_ops tcp_request_sock_ops __read_mostly = { .send_reset = tcp_v4_send_reset, }; +struct request_sock_ops tcp4_extend_request_sock_ops__read_mostly = { + .family =PF_INET , + .obj_size =sizeof (struct extend_request_sock ), + .rtx_syn_ack = tcp_v4_send_synack, + .send_ack = tcp_v4_reqsk_send_ack, + .destructor = tcp_v4_reqsk_destructor, + .send_reset = tcp_v4_send_reset, +}; +
...
+ req = inet_reqsk_alloc(&tcp4_extend_request_sock_ops);
+ if (NULL == req)
+ goto drop;
+
Many hours of investigation demonstrated that the obj_size isn't actually used to allocate the structure. Heck, it's not even checked to determine whether there's enough room! Instead, the kernel crashes later, as the extended variables are accessed!
Returning to the architecturally clean parameters of the previous patch series, that has the distinct advantage of actually working....