Good UTC day everyone!
I've posted it to netfilter-devel, thought it is more relevant there, but it has sparked no interest whatsoever. So I try here.
I use libiptc (iptables-1.4.21-r1) to manage the iptables rules that
use my custom module. The module (after starvation) looks like:
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
struct xt_FAN_info {
__u32 par;
};
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yury A. Pukhalsky <aikipooh@xxxxxxxxx>");
MODULE_DESCRIPTION("None");
MODULE_ALIAS("ipt_FAN");
static int
fan_tg_check( const struct xt_tgchk_param *par )
{
struct xt_FAN_info *einfo = par->targinfo;
pr_notice( "FAN check: par=%d\n", einfo->par );
return 0;
}
static void
fan_tg_destroy( const struct xt_tgdtor_param *par )
{
struct xt_FAN_info *einfo = par->targinfo;
pr_notice( "Destroying par=%d\n", einfo->par );
}
static struct xt_target fan_tg_reg __read_mostly = {
.name = "FAN",
.family = NFPROTO_UNSPEC,
.targetsize = sizeof(struct xt_FAN_info),
.table = "mangle",
.checkentry = fan_tg_check,
.destroy = fan_tg_destroy,
.me = THIS_MODULE,
};
static int __init fan_tg_init(void)
{
pr_notice("FAN init\n" );
return xt_register_target( &fan_tg_reg );
}
static void __exit fan_tg_exit(void)
{
pr_notice("FAN exit\n" );
xt_unregister_target( &fan_tg_reg );
}
module_init( fan_tg_init );
module_exit( fan_tg_exit );
The control program that adds the rule (takes a parameter that the
module outputs) is this:
#include <libiptc/libiptc.h>
#include <errno.h>
struct xt_FAN_info {
__u32 srv_addr;
};
typedef struct {
struct ipt_entry e;
struct xt_entry_match m;
struct xt_tcp mtcp;
struct xt_entry_target t;
struct xt_FAN_info d;
} rule_t;
int main( int argc, char **argv )
{
if( argc != 2 ) return 1;
struct xtc_handle *h = iptc_init( "mangle" );
if(!h) {
printf("%s\n", iptc_strerror(errno));
exit(1);
}
rule_t rule = {
.e = {
.ip.proto = IPPROTO_TCP,
.ip.src.s_addr=inet_addr("10.214.217.48"),
.ip.smsk.s_addr = htonl(0xffffffff)
},
.m.u.user.name = "tcp",
.m.u.user.match_size = XT_ALIGN( sizeof( struct xt_entry_match ) +
sizeof( struct xt_tcp ) ),
.mtcp = { .spts = {1023, 60535}, .dpts = {80,80} },
.t.u.user.name = "FAN",
.t.u.user.target_size = XT_ALIGN( sizeof( struct xt_entry_target ) +
sizeof( struct xt_FAN_info ) ),
.d = { atoi(argv[1]) }
};
rule.e.target_offset = sizeof(struct ipt_entry)
+ sizeof( struct xt_entry_match ) + sizeof( struct xt_tcp );
rule.e.next_offset = XT_ALIGN( rule.e.target_offset +
rule.t.u.user.target_size );
if( !iptc_append_entry( "OUTPUT", (struct ipt_entry *) &rule, h) ) {
printf("append: %s\n", iptc_strerror(errno));
exit(1);
}
if( !iptc_commit( h ) ) {
printf("commit: %s\n", iptc_strerror(errno));
exit(1);
}
iptc_free( h );
return 0;
}
I call this program several times, adding rules one by one:
localhost debug_mnl # ./control 1
localhost debug_mnl # ./control 2
localhost debug_mnl # ./control 3
localhost debug_mnl # ./control 4
And in the end I have 4 rules, as intended:
FAN tcp -- 10.214.217.48 0.0.0.0/0 tcp
spts:1023:60535 dpt:80[8 bytes of unknown target data]
FAN tcp -- 10.214.217.48 0.0.0.0/0 tcp
spts:1023:60535 dpt:80[8 bytes of unknown target data]
FAN tcp -- 10.214.217.48 0.0.0.0/0 tcp
spts:1023:60535 dpt:80[8 bytes of unknown target data]
FAN tcp -- 10.214.217.48 0.0.0.0/0 tcp
spts:1023:60535 dpt:80[8 bytes of unknown target data]
Yet the output of the kernel module looks funny:
Mar 23 02:43:07 localhost kernel: [ 3326.340475] FAN init
Mar 23 02:43:07 localhost kernel: [ 3326.342503] FAN check: par=1
Mar 23 02:43:12 localhost kernel: [ 3331.946819] FAN check: par=1
Mar 23 02:43:12 localhost kernel: [ 3331.946844] FAN check: par=2
Mar 23 02:43:12 localhost kernel: [ 3331.946893] Destroying par=1
Mar 23 02:43:21 localhost kernel: [ 3340.643805] FAN check: par=1
Mar 23 02:43:21 localhost kernel: [ 3340.643828] FAN check: par=2
Mar 23 02:43:21 localhost kernel: [ 3340.643836] FAN check: par=3
Mar 23 02:43:21 localhost kernel: [ 3340.643883] Destroying par=1
Mar 23 02:43:21 localhost kernel: [ 3340.643889] Destroying par=2
Mar 23 02:43:25 localhost kernel: [ 3344.424060] FAN check: par=1
Mar 23 02:43:25 localhost kernel: [ 3344.424084] FAN check: par=2
Mar 23 02:43:25 localhost kernel: [ 3344.424091] FAN check: par=3
Mar 23 02:43:25 localhost kernel: [ 3344.424098] FAN check: par=4
Mar 23 02:43:25 localhost kernel: [ 3344.424144] Destroying par=1
Mar 23 02:43:25 localhost kernel: [ 3344.424150] Destroying par=2
Mar 23 02:43:25 localhost kernel: [ 3344.424155] Destroying par=3
I think something's not cleaned up there.
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