xref: /openbmc/linux/kernel/pid_sysctl.h (revision 9876cfe8)
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)
pid_mfd_noexec_dointvec_minmax(struct ctl_table * table,int write,void * buf,size_t * lenp,loff_t * ppos)8 static 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 
34 static 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 };
register_pid_ns_sysctl_table_vm(void)46 static inline void register_pid_ns_sysctl_table_vm(void)
47 {
48 	register_sysctl("vm", pid_ns_ctl_table_vm);
49 }
50 #else
register_pid_ns_sysctl_table_vm(void)51 static inline void register_pid_ns_sysctl_table_vm(void) {}
52 #endif
53 
54 #endif /* LINUX_PID_SYSCTL_H */
55