kernel/pid_sysctl.h

   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)
   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 };
  46 static inline void register_pid_ns_sysctl_table_vm(void)
  47 {
  48         register_sysctl("vm", pid_ns_ctl_table_vm);
  49 }
  50 #else
  51 static inline void register_pid_ns_sysctl_table_vm(void) {}
  52 #endif
  53
  54 #endif /* LINUX_PID_SYSCTL_H */