sysctl: treewide: constify ctl_table_header::ctl_table_arg

To be able to constify instances of struct ctl_tables it is necessary to
remove ways through which non-const versions are exposed from the
sysctl core.
One of these is the ctl_table_arg member of struct ctl_table_header.

Constify this reference as a prerequisite for the full constification of
struct ctl_table instances.
No functional change.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vrf.c

@@ -1971,7 +1971,7 @@ static int vrf_netns_init_sysctl(struct net *net, struct netns_vrf *nn_vrf)
 static void vrf_netns_exit_sysctl(struct net *net)
 {
 	struct netns_vrf *nn_vrf = net_generic(net, vrf_net_id);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = nn_vrf->ctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(nn_vrf->ctl_hdr);

include/linux/sysctl.h

@@ -182,7 +182,7 @@ struct ctl_table_header {
 		struct rcu_head rcu;
 	};
 	struct completion *unregistering;
-	struct ctl_table *ctl_table_arg;
+	const struct ctl_table *ctl_table_arg;
 	struct ctl_table_root *root;
 	struct ctl_table_set *set;
 	struct ctl_dir *parent;

ipc/ipc_sysctl.c

@@ -306,7 +306,7 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
 
 void retire_ipc_sysctls(struct ipc_namespace *ns)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->ipc_sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->ipc_sysctls);

ipc/mq_sysctl.c

@@ -160,7 +160,7 @@ bool setup_mq_sysctls(struct ipc_namespace *ns)
 
 void retire_mq_sysctls(struct ipc_namespace *ns)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->mq_sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->mq_sysctls);

kernel/ucount.c

@@ -119,7 +119,7 @@ bool setup_userns_sysctls(struct user_namespace *ns)
 void retire_userns_sysctls(struct user_namespace *ns)
 {
 #ifdef CONFIG_SYSCTL
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = ns->sysctls->ctl_table_arg;
 	unregister_sysctl_table(ns->sysctls);

net/ax25/sysctl_net_ax25.c

@@ -171,7 +171,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
 void ax25_unregister_dev_sysctl(ax25_dev *ax25_dev)
 {
 	struct ctl_table_header *header = ax25_dev->sysheader;
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (header) {
 		ax25_dev->sysheader = NULL;

net/bridge/br_netfilter_hooks.c

@@ -1275,7 +1275,7 @@ static int br_netfilter_sysctl_init_net(struct net *net)
 static void br_netfilter_sysctl_exit_net(struct net *net,
 					 struct brnf_net *brnet)
 {
-	struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg;
+	const struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg;
 
 	unregister_net_sysctl_table(brnet->ctl_hdr);
 	if (!net_eq(net, &init_net))

net/core/sysctl_net_core.c

@@ -743,7 +743,7 @@ static __net_init int sysctl_core_net_init(struct net *net)
 
 static __net_exit void sysctl_core_net_exit(struct net *net)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->core.sysctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->core.sysctl_hdr);

net/ieee802154/6lowpan/reassembly.c

@@ -399,7 +399,7 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
 
 static void __net_exit lowpan_frags_ns_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 	struct netns_ieee802154_lowpan *ieee802154_lowpan =
 		net_ieee802154_lowpan(net);
 

net/ipv4/devinet.c

@@ -2749,7 +2749,7 @@ static __net_init int devinet_init_net(struct net *net)
 static __net_exit void devinet_exit_net(struct net *net)
 {
 #ifdef CONFIG_SYSCTL
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->ipv4.forw_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.forw_hdr);

net/ipv4/ip_fragment.c

@@ -632,7 +632,7 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
 
 static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->ipv4.frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.frags_hdr);

net/ipv4/route.c

@@ -3576,7 +3576,7 @@ static __net_init int sysctl_route_net_init(struct net *net)
 
 static __net_exit void sysctl_route_net_exit(struct net *net)
 {
-	struct ctl_table *tbl;
+	const struct ctl_table *tbl;
 
 	tbl = net->ipv4.route_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv4.route_hdr);

net/ipv4/sysctl_net_ipv4.c

@@ -1554,7 +1554,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 
 static __net_exit void ipv4_sysctl_exit_net(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	kfree(net->ipv4.sysctl_local_reserved_ports);
 	table = net->ipv4.ipv4_hdr->ctl_table_arg;

net/ipv4/xfrm4_policy.c

@@ -186,7 +186,7 @@ static __net_init int xfrm4_net_sysctl_init(struct net *net)
 
 static __net_exit void xfrm4_net_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!net->ipv4.xfrm4_hdr)
 		return;

net/ipv6/addrconf.c

@@ -7238,7 +7238,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
 static void __addrconf_sysctl_unregister(struct net *net,
 					 struct ipv6_devconf *p, int ifindex)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!p->sysctl_header)
 		return;

net/ipv6/netfilter/nf_conntrack_reasm.c

@@ -105,7 +105,7 @@ static int nf_ct_frag6_sysctl_register(struct net *net)
 static void __net_exit nf_ct_frags6_sysctl_unregister(struct net *net)
 {
 	struct nft_ct_frag6_pernet *nf_frag = nf_frag_pernet(net);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = nf_frag->nf_frag_frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(nf_frag->nf_frag_frags_hdr);

net/ipv6/reassembly.c

@@ -487,7 +487,7 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
 
 static void __net_exit ip6_frags_ns_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->ipv6.sysctl.frags_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->ipv6.sysctl.frags_hdr);

net/ipv6/sysctl_net_ipv6.c

@@ -313,9 +313,9 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 
 static void __net_exit ipv6_sysctl_net_exit(struct net *net)
 {
-	struct ctl_table *ipv6_table;
-	struct ctl_table *ipv6_route_table;
-	struct ctl_table *ipv6_icmp_table;
+	const struct ctl_table *ipv6_table;
+	const struct ctl_table *ipv6_route_table;
+	const struct ctl_table *ipv6_icmp_table;
 
 	ipv6_table = net->ipv6.sysctl.hdr->ctl_table_arg;
 	ipv6_route_table = net->ipv6.sysctl.route_hdr->ctl_table_arg;

net/ipv6/xfrm6_policy.c

@@ -218,7 +218,7 @@ static int __net_init xfrm6_net_sysctl_init(struct net *net)
 
 static void __net_exit xfrm6_net_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!net->ipv6.sysctl.xfrm6_hdr)
 		return;

net/mpls/af_mpls.c

@@ -1422,7 +1422,7 @@ static void mpls_dev_sysctl_unregister(struct net_device *dev,
 				       struct mpls_dev *mdev)
 {
 	struct net *net = dev_net(dev);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	if (!mdev->sysctl)
 		return;
@@ -2690,7 +2690,7 @@ static void mpls_net_exit(struct net *net)
 {
 	struct mpls_route __rcu **platform_label;
 	size_t platform_labels;
-	struct ctl_table *table;
+	const struct ctl_table *table;
 	unsigned int index;
 
 	table = net->mpls.ctl->ctl_table_arg;

net/mptcp/ctrl.c

@@ -198,7 +198,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 
 static void mptcp_pernet_del_table(struct mptcp_pernet *pernet)
 {
-	struct ctl_table *table = pernet->ctl_table_hdr->ctl_table_arg;
+	const struct ctl_table *table = pernet->ctl_table_hdr->ctl_table_arg;
 
 	unregister_net_sysctl_table(pernet->ctl_table_hdr);
 

net/netfilter/nf_conntrack_standalone.c

@@ -1122,7 +1122,7 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net)
 static void nf_conntrack_standalone_fini_sysctl(struct net *net)
 {
 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = cnet->sysctl_header->ctl_table_arg;
 	unregister_net_sysctl_table(cnet->sysctl_header);

net/netfilter/nf_log.c

@@ -514,7 +514,7 @@ static int netfilter_log_sysctl_init(struct net *net)
 
 static void netfilter_log_sysctl_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->nf.nf_log_dir_header->ctl_table_arg;
 	unregister_net_sysctl_table(net->nf.nf_log_dir_header);

net/sctp/sysctl.c

@@ -624,7 +624,7 @@ int sctp_sysctl_net_register(struct net *net)
 
 void sctp_sysctl_net_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->sctp.sysctl_header->ctl_table_arg;
 	unregister_net_sysctl_table(net->sctp.sysctl_header);

net/smc/smc_sysctl.c

@@ -133,7 +133,7 @@ int __net_init smc_sysctl_net_init(struct net *net)
 
 void __net_exit smc_sysctl_net_exit(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->smc.smc_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->smc.smc_hdr);

net/unix/sysctl_net_unix.c

@@ -52,7 +52,7 @@ int __net_init unix_sysctl_register(struct net *net)
 
 void unix_sysctl_unregister(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->unx.ctl->ctl_table_arg;
 	unregister_net_sysctl_table(net->unx.ctl);

net/xfrm/xfrm_sysctl.c

@@ -76,7 +76,7 @@ int __net_init xfrm_sysctl_init(struct net *net)
 
 void __net_exit xfrm_sysctl_fini(struct net *net)
 {
-	struct ctl_table *table;
+	const struct ctl_table *table;
 
 	table = net->xfrm.sysctl_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->xfrm.sysctl_hdr);