/* SPDX-License-Identifier: GPL-2.0 */
#ifndef LINUX_PID_SYSCTL_H
#define LINUX_PID_SYSCTL_H

#include <linux/pid_namespace.h>

#if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE)
static int pid_mfd_noexec_dointvec_minmax(const struct ctl_table *table,
        int write, void *buf, size_t *lenp, loff_t *ppos)
{
        struct pid_namespace *ns = task_active_pid_ns(current);
        struct ctl_table table_copy;
        int err, scope, parent_scope;

        if (write && !ns_capable(ns->user_ns, CAP_SYS_ADMIN))
                return -EPERM;

        table_copy = *table;

        /* You cannot set a lower enforcement value than your parent. */
        parent_scope = pidns_memfd_noexec_scope(ns->parent);
        /* Equivalent to pidns_memfd_noexec_scope(ns). */
        scope = max(READ_ONCE(ns->memfd_noexec_scope), parent_scope);

        table_copy.data = &scope;
        table_copy.extra1 = &parent_scope;

        err = proc_dointvec_minmax(&table_copy, write, buf, lenp, ppos);
        if (!err && write)
                WRITE_ONCE(ns->memfd_noexec_scope, scope);
        return err;
}

static const struct ctl_table pid_ns_ctl_table_vm[] = {
        {
                .procname       = "memfd_noexec",
                .data           = &init_pid_ns.memfd_noexec_scope,
                .maxlen         = sizeof(init_pid_ns.memfd_noexec_scope),
                .mode           = 0644,
                .proc_handler   = pid_mfd_noexec_dointvec_minmax,
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_TWO,
        },
};
static inline void register_pid_ns_sysctl_table_vm(void)
{
        register_sysctl("vm", pid_ns_ctl_table_vm);
}
#else
static inline void register_pid_ns_sysctl_table_vm(void) {}
#endif

#endif /* LINUX_PID_SYSCTL_H */