elf: Do not fail for failed dlmopen on audit modules (BZ #28061)

The dl_main sets the LM_ID_BASE to RT_ADD just before starting to
add load new shared objects.  The state is set to RT_CONSISTENT just
after all objects are loaded.

However if a audit modules tries to dlmopen an inexistent module,
the _dl_open will assert that the namespace is in an inconsistent
state.

This is different than dlopen, since first it will not use
LM_ID_BASE and second _dl_map_object_from_fd is the sole responsible
to set and reset the r_state value.

So the assert on _dl_open can not really be seen if the state is
consistent, since _dt_main resets it.  This patch removes the assert.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

elf/Makefile

@@ -232,6 +232,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-dl-is_dso tst-ro-dynamic \
 	 tst-audit18 \
 	 tst-audit19b \
+	 tst-audit20 \
 	 tst-audit22 \
 	 tst-rtld-run-static \
 #	 reldep9
@@ -383,6 +384,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-auditmod19a \
 		tst-auditmod19b \
 		tst-audit19bmod \
+		tst-auditmod20 \
 		tst-auditmod22 \
 
 # Most modules build with _ISOMAC defined, but those filtered out
@@ -1596,6 +1598,9 @@ $(objpfx)tst-audit19b.out: $(objpfx)tst-auditmod19b.so
 $(objpfx)tst-audit19b: $(objpfx)tst-audit19bmod.so
 tst-audit19b-ARGS = -- $(host-test-program-cmd)
 
+$(objpfx)tst-audit20.out: $(objpfx)tst-auditmod20.so
+tst-audit20-ENV = LD_AUDIT=$(objpfx)tst-auditmod20.so
+
 $(objpfx)tst-audit22.out: $(objpfx)tst-auditmod22.so
 tst-audit22-ARGS = -- $(host-test-program-cmd)
 

elf/dl-open.c

@@ -914,8 +914,6 @@ no more namespaces available for dlmopen()"));
 	     the flag here.  */
 	}
 
-      assert (_dl_debug_update (args.nsid)->r_state == RT_CONSISTENT);
-
       /* Release the lock.  */
       __rtld_lock_unlock_recursive (GL(dl_load_lock));
 

elf/tst-audit20.c

@@ -0,0 +1,25 @@
+/* Check dlopen failure on audit modules.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+static int
+do_test (void)
+{
+  return 0;
+}
+
+#include <support/test-driver.c>

elf/tst-auditmod20.c

@@ -0,0 +1,57 @@
+/* Check dlopen failure on audit modules.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dlfcn.h>
+#include <link.h>
+#include <stdlib.h>
+
+unsigned int
+la_version (unsigned int v)
+{
+  return LAV_CURRENT;
+}
+
+static void
+check (void)
+{
+  {
+    void *mod = dlopen ("nonexistent.so", RTLD_NOW);
+    if (mod != NULL)
+      abort ();
+  }
+
+  {
+    void *mod = dlmopen (LM_ID_BASE, "nonexistent.so", RTLD_NOW);
+    if (mod != NULL)
+      abort ();
+  }
+}
+
+void
+la_activity (uintptr_t *cookie, unsigned int flag)
+{
+  if (flag != LA_ACT_CONSISTENT)
+    return;
+  check ();
+}
+
+void
+la_preinit (uintptr_t *cookie)
+{
+  check ();
+}