<varlistentry>
<term><option>-U</option></term>
- <listitem><para>Equivalent to <option>--private-users=pick</option>.</para></listitem>
+ <listitem><para>If the kernel supports the user namespaces feature, equivalent to
+ <option>--private-users=pick</option>, otherwise equivalent to
+ <option>--private-users=no</option>.</para></listitem>
</varlistentry>
<varlistentry>
#include <stdbool.h>
#include <sys/types.h>
+#include <unistd.h>
bool uid_is_valid(uid_t uid);
#define PTR_TO_GID(p) ((gid_t) (((uintptr_t) (p))-1))
#define GID_TO_PTR(u) ((void*) (((uintptr_t) (u))+1))
+
+static inline bool userns_supported(void) {
+ return access("/proc/self/uid_map", F_OK) >= 0;
+}
break;
case 'U':
- arg_userns_mode = USER_NAMESPACE_PICK;
- arg_uid_shift = UID_INVALID;
- arg_uid_range = UINT32_C(0x10000);
+ if (userns_supported()) {
+ arg_userns_mode = USER_NAMESPACE_PICK;
+ arg_uid_shift = UID_INVALID;
+ arg_uid_range = UINT32_C(0x10000);
+
+ arg_settings_mask |= SETTING_USERNS;
+ }
- arg_settings_mask |= SETTING_USERNS;
break;
case ARG_PRIVATE_USERS_CHOWN:
return -EINVAL;
}
- if (arg_userns_mode != USER_NAMESPACE_NO && access("/proc/self/uid_map", F_OK) < 0) {
+ if (arg_userns_mode != USER_NAMESPACE_NO && !userns_supported()) {
log_error("--private-users= is not supported, kernel compiled without user namespace support.");
return -EOPNOTSUPP;
}