uwrap: Allow setuid calls only for privileged users

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Andreas Schneider <asn@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>

diff --git a/lib/uid_wrapper/uid_wrapper.c b/lib/uid_wrapper/uid_wrapper.c
index da8a2759f09083c4a5fb9fc9d140d73d5ea04e78..e0d84beb7ea7769c611deee085a560d00f61b41b 100644 (file)
--- a/lib/uid_wrapper/uid_wrapper.c
+++ b/lib/uid_wrapper/uid_wrapper.c
@@ -1184,6 +1184,61 @@ static int uwrap_setreuid(uid_t ruid, uid_t euid)
 }
 #endif
 
+static int uwrap_setuid_args(uid_t uid,
+                            uid_t *new_ruid,
+                            uid_t *new_euid,
+                            uid_t *new_suid)
+{
+       struct uwrap_thread *id = uwrap_tls_id;
+
+       UWRAP_LOG(UWRAP_LOG_TRACE,
+                 "uid %d -> %d",
+                 id->ruid, uid);
+
+       if (uid == (uid_t)-1) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       if (id->euid == 0) {
+               *new_suid = *new_ruid = uid;
+       } else if (uid != id->ruid &&
+                  uid != id->suid) {
+               errno = EPERM;
+               return -1;
+       }
+
+       *new_euid = uid;
+
+       return 0;
+}
+
+static int uwrap_setuid_thread(uid_t uid)
+{
+       uid_t new_ruid = -1, new_euid = -1, new_suid = -1;
+       int rc;
+
+       rc = uwrap_setuid_args(uid, &new_ruid, &new_euid, &new_suid);
+       if (rc != 0) {
+               return rc;
+       }
+
+       return uwrap_setresuid_thread(new_ruid, new_euid, new_suid);
+}
+
+static int uwrap_setuid(uid_t uid)
+{
+       uid_t new_ruid = -1, new_euid = -1, new_suid = -1;
+       int rc;
+
+       rc = uwrap_setuid_args(uid, &new_ruid, &new_euid, &new_suid);
+       if (rc != 0) {
+               return rc;
+       }
+
+       return uwrap_setresuid(new_ruid, new_euid, new_suid);
+}
+
 /*
  * UWRAP_GETxUID FUNCTIONS
  */
@@ -1232,7 +1287,7 @@ int setuid(uid_t uid)
        }
 
        uwrap_init();
-       return uwrap_setresuid(uid, -1, -1);
+       return uwrap_setuid(uid);
 }
 
 #ifdef HAVE_SETEUID
@@ -1728,7 +1783,7 @@ static long int uwrap_syscall (long int sysno, va_list vp)
                        {
                                uid_t uid = (uid_t) va_arg(vp, uid_t);
 
-                               rc = uwrap_setresuid_thread(uid, -1, -1);
+                               rc = uwrap_setuid_thread(uid);
                        }
                        break;
                case SYS_setreuid: