1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef LINUX_PID_SYSCTL_H
3#define LINUX_PID_SYSCTL_H
4
5#include <linux/pid_namespace.h>
6
7#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
8static int pid_mfd_noexec_dointvec_minmax(struct ctl_table *table,
9	int write, void *buf, size_t *lenp, loff_t *ppos)
10{
11	struct pid_namespace *ns = task_active_pid_ns(current);
12	struct ctl_table table_copy;
13	int err, scope, parent_scope;
14
15	if (write && !ns_capable(ns->user_ns, CAP_SYS_ADMIN))
16		return -EPERM;
17
18	table_copy = *table;
19
20	/* You cannot set a lower enforcement value than your parent. */
21	parent_scope = pidns_memfd_noexec_scope(ns->parent);
22	/* Equivalent to pidns_memfd_noexec_scope(ns). */
23	scope = max(READ_ONCE(ns->memfd_noexec_scope), parent_scope);
24
25	table_copy.data = &scope;
26	table_copy.extra1 = &parent_scope;
27
28	err = proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
29	if (!err && write)
30		WRITE_ONCE(ns->memfd_noexec_scope, scope);
31	return err;
32}
33
34static struct ctl_table pid_ns_ctl_table_vm[] = {
35	{
36		.procname	= "memfd_noexec",
37		.data		= &init_pid_ns.memfd_noexec_scope,
38		.maxlen		= sizeof(init_pid_ns.memfd_noexec_scope),
39		.mode		= 0644,
40		.proc_handler	= pid_mfd_noexec_dointvec_minmax,
41		.extra1		= SYSCTL_ZERO,
42		.extra2		= SYSCTL_TWO,
43	},
44	{ }
45};
46static inline void register_pid_ns_sysctl_table_vm(void)
47{
48	register_sysctl("vm", pid_ns_ctl_table_vm);
49}
50#else
51static inline void register_pid_ns_sysctl_table_vm(void) {}
52#endif
53
54#endif /* LINUX_PID_SYSCTL_H */
55