// SPDX-License-Identifier: GPL-2.0-only/* -*- linux-c -*- * sysctl_net.c: sysctl interface to net subsystem. * * Begun April 1, 1996, Mike Shaver. * Added /proc/sys/net directories for each protocol family. [MS] * * Revision 1.2  1996/05/08  20:24:40  shaver * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and * NET_IPV4_IP_FORWARD. * * */ #include <linux/mm.h>#include <linux/export.h>#include <linux/sysctl.h>#include <linux/nsproxy.h> #include <net/sock.h> #ifdef CONFIG_INET#include <net/ip.h>#endif #ifdef CONFIG_NET#include <linux/if_ether.h>#endif static struct ctl_table_set *net_ctl_header_lookup(struct ctl_table_root *root){	return &current->nsproxy->net_ns->sysctls;} static int is_seen(struct ctl_table_set *set){	return &current->nsproxy->net_ns->sysctls == set;} /* Return standard mode bits for table entry. */static int net_ctl_permissions(struct ctl_table_header *head,			       struct ctl_table *table){	struct net *net = container_of(head->set, struct net, sysctls); 	/* Allow network administrator to have same access as root. */	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {		int mode = (table->mode >> 6) & 7;		return (mode << 6) | (mode << 3) | mode;	} 	return table->mode;} static void net_ctl_set_ownership(struct ctl_table_header *head,				  struct ctl_table *table,				  kuid_t *uid, kgid_t *gid){	struct net *net = container_of(head->set, struct net, sysctls);	kuid_t ns_root_uid;	kgid_t ns_root_gid; 	ns_root_uid = make_kuid(net->user_ns, 0);	if (uid_valid(ns_root_uid))		*uid = ns_root_uid; 	ns_root_gid = make_kgid(net->user_ns, 0);	if (gid_valid(ns_root_gid))		*gid = ns_root_gid;} static struct ctl_table_root net_sysctl_root = {	.lookup = net_ctl_header_lookup,	.permissions = net_ctl_permissions,	.set_ownership = net_ctl_set_ownership,}; static int __net_init sysctl_net_init(struct net *net){	setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);	return 0;} static void __net_exit sysctl_net_exit(struct net *net){	retire_sysctl_set(&net->sysctls);} static struct pernet_operations sysctl_pernet_ops = {	.init = sysctl_net_init,	.exit = sysctl_net_exit,}; static struct ctl_table_header *net_header;__init int net_sysctl_init(void){	static struct ctl_table empty[1];	int ret = -ENOMEM;	/* Avoid limitations in the sysctl implementation by	 * registering "/proc/sys/net" as an empty directory not in a	 * network namespace.	 */	net_header = register_sysctl("net", empty);	if (!net_header)		goto out;	ret = register_pernet_subsys(&sysctl_pernet_ops);	if (ret)		goto out1;out:	return ret;out1:	unregister_sysctl_table(net_header);	net_header = NULL;	goto out;} /* Verify that sysctls for non-init netns are safe by either: * 1) being read-only, or * 2) having a data pointer which points outside of the global kernel/module *    data segment, and rather into the heap where a per-net object was *    allocated. */static void ensure_safe_net_sysctl(struct net *net, const char *path,				   struct ctl_table *table){	struct ctl_table *ent; 	pr_debug("Registering net sysctl (net %p): %s\n", net, path);	for (ent = table; ent->procname; ent++) {		unsigned long addr;		const char *where; 		pr_debug("  procname=%s mode=%o proc_handler=%ps data=%p\n",			 ent->procname, ent->mode, ent->proc_handler, ent->data); 		/* If it's not writable inside the netns, then it can't hurt. */		if ((ent->mode & 0222) == 0) {			pr_debug("    Not writable by anyone\n");			continue;		} 		/* Where does data point? */		addr = (unsigned long)ent->data;		if (is_module_address(addr))			where = "module";		else if (core_kernel_data(addr))			where = "kernel";		else			continue; 		/* If it is writable and points to kernel/module global		 * data, then it's probably a netns leak.		 */		WARN(1, "sysctl %s/%s: data points to %s global data: %ps\n",		     path, ent->procname, where, ent->data); 		/* Make it "safe" by dropping writable perms */		ent->mode &= ~0222;	}} struct ctl_table_header *register_net_sysctl(struct net *net,	const char *path, struct ctl_table *table){	if (!net_eq(net, &init_net))		ensure_safe_net_sysctl(net, path, table); 	return __register_sysctl_table(&net->sysctls, path, table);}EXPORT_SYMBOL_GPL(register_net_sysctl); void unregister_net_sysctl_table(struct ctl_table_header *header){	unregister_sysctl_table(header);}EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);