netfilter: conntrack: limit sysctl setting for boolean options

We use the zero and one to limit the boolean options setting.
After this patch we only set 0 or 1 to boolean options for nf
conntrack sysctl.
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netns/conntrack.h

@@ -24,9 +24,9 @@ struct nf_generic_net {
 
 struct nf_tcp_net {
 	unsigned int timeouts[TCP_CONNTRACK_TIMEOUT_MAX];
-	unsigned int tcp_loose;
-	unsigned int tcp_be_liberal;
-	unsigned int tcp_max_retrans;
+	int tcp_loose;
+	int tcp_be_liberal;
+	int tcp_max_retrans;
 };
 
 enum udp_conntrack {

net/netfilter/nf_conntrack_standalone.c

@@ -511,6 +511,8 @@ static void nf_conntrack_standalone_fini_proc(struct net *net)
 /* Log invalid packets of a given protocol */
 static int log_invalid_proto_min __read_mostly;
 static int log_invalid_proto_max __read_mostly = 255;
+static int zero;
+static int one = 1;
 
 /* size the user *wants to set */
 static unsigned int nf_conntrack_htable_size_user __read_mostly;
@@ -624,9 +626,11 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 	[NF_SYSCTL_CT_CHECKSUM] = {
 		.procname	= "nf_conntrack_checksum",
 		.data		= &init_net.ct.sysctl_checksum,
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 	[NF_SYSCTL_CT_LOG_INVALID] = {
 		.procname	= "nf_conntrack_log_invalid",
@@ -647,33 +651,41 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 	[NF_SYSCTL_CT_ACCT] = {
 		.procname	= "nf_conntrack_acct",
 		.data		= &init_net.ct.sysctl_acct,
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 	[NF_SYSCTL_CT_HELPER] = {
 		.procname	= "nf_conntrack_helper",
 		.data		= &init_net.ct.sysctl_auto_assign_helper,
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
 	[NF_SYSCTL_CT_EVENTS] = {
 		.procname	= "nf_conntrack_events",
 		.data		= &init_net.ct.sysctl_events,
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 #endif
 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
 	[NF_SYSCTL_CT_TIMESTAMP] = {
 		.procname	= "nf_conntrack_timestamp",
 		.data		= &init_net.ct.sysctl_tstamp,
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 #endif
 	[NF_SYSCTL_CT_PROTO_TIMEOUT_GENERIC] = {
@@ -744,15 +756,19 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 	},
 	[NF_SYSCTL_CT_PROTO_TCP_LOOSE] = {
 		.procname	= "nf_conntrack_tcp_loose",
-		.maxlen		= sizeof(unsigned int),
+		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 	[NF_SYSCTL_CT_PROTO_TCP_LIBERAL] = {
 		.procname       = "nf_conntrack_tcp_be_liberal",
-		.maxlen         = sizeof(unsigned int),
+		.maxlen         = sizeof(int),
 		.mode           = 0644,
-		.proc_handler   = proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 	[NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS] = {
 		.procname	= "nf_conntrack_tcp_max_retrans",
@@ -887,7 +903,9 @@ static struct ctl_table nf_ct_sysctl_table[] = {
 		.procname	= "nf_conntrack_dccp_loose",
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1 	= &zero,
+		.extra2 	= &one,
 	},
 #endif
 #ifdef CONFIG_NF_CT_PROTO_GRE