commit b2964eb1d9a6b8ab1250e8a881cf406182da5875

Author: Florian Weimer <fweimer@redhat.com>

Date:   Wed Apr 21 19:49:51 2021 +0200

    dlfcn: Failures after dlmopen should not terminate process [BZ #24772]

    Commit 9e78f6f6e7134a5f299cc8de77370218f8019237 ("Implement

    _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]") has the

    side effect that distinct namespaces, as created by dlmopen, now have

    separate implementations of the rtld exception mechanism.  This means

    that the call to _dl_catch_error from libdl in a secondary namespace

    does not actually install an exception handler because the

    thread-local variable catch_hook in the libc.so copy in the secondary

    namespace is distinct from that of the base namepace.  As a result, a

    dlsym/dlopen/... failure in a secondary namespace terminates the process

    with a dynamic linker error because it looks to the exception handler

    mechanism as if no handler has been installed.

    This commit restores GLRO (dl_catch_error) and uses it to set the

    handler in the base namespace.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Conflicts:

	elf/Makefile

diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c

index 06732460ea1512cd..e08ac3afef302817 100644

--- a/dlfcn/dlerror.c

+++ b/dlfcn/dlerror.c

@@ -167,8 +167,10 @@ _dlerror_run (void (*operate) (void *), void *args)

       result->errstring = NULL;

     }

-  result->errcode = _dl_catch_error (&result->objname, &result->errstring,

-				     &result->malloced, operate, args);

+  result->errcode = GLRO (dl_catch_error) (&result->objname,

+					   &result->errstring,

+					   &result->malloced,

+					   operate, args);

   /* If no error we mark that no error string is available.  */

   result->returned = result->errstring == NULL;

diff --git a/elf/Makefile b/elf/Makefile

index a811919ba4568d64..e0919486a14cab1a 100644

--- a/elf/Makefile

+++ b/elf/Makefile

@@ -216,6 +216,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \

 	 tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \

 	 tst-tls20 tst-tls21 \

 	 tst-rtld-run-static \

+	 tst-dlmopen-dlerror \

 #	 reldep9

 tests-internal += loadtest unload unload2 circleload1 \

 	 neededtest neededtest2 neededtest3 neededtest4 \

@@ -349,6 +350,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \

 		libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \

 		libmarkermod5-1 libmarkermod5-2 libmarkermod5-3 libmarkermod5-4 \

 		libmarkermod5-5 tst-tls20mod-bad tst-tls21mod \

+		tst-dlmopen-dlerror-mod \

 # Most modules build with _ISOMAC defined, but those filtered out

 # depend on internal headers.

@@ -1546,6 +1548,10 @@ $(objpfx)tst-sonamemove-dlopen.out: \

   $(objpfx)tst-sonamemove-runmod1.so \

   $(objpfx)tst-sonamemove-runmod2.so

+$(objpfx)tst-dlmopen-dlerror: $(libdl)

+$(objpfx)tst-dlmopen-dlerror-mod.so: $(libdl) $(libsupport)

+$(objpfx)tst-dlmopen-dlerror.out: $(objpfx)tst-dlmopen-dlerror-mod.so

+

 # Override -z defs, so that we can reference an undefined symbol.

 # Force lazy binding for the same reason.

 LDFLAGS-tst-latepthreadmod.so = \

diff --git a/elf/dl-error-skeleton.c b/elf/dl-error-skeleton.c

index 9cb002ccfed2c7b4..7801aa433b12275f 100644

--- a/elf/dl-error-skeleton.c

+++ b/elf/dl-error-skeleton.c

@@ -248,4 +248,16 @@ _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)

   catch_hook = old_catch;

   receiver = old_receiver;

 }

+

+/* Forwarder used for initializing GLRO (_dl_catch_error).  */

+int

+_rtld_catch_error (const char **objname, const char **errstring,

+		   bool *mallocedp, void (*operate) (void *),

+		   void *args)

+{

+  /* The reference to _dl_catch_error will eventually be relocated to

+     point to the implementation in libc.so.  */

+  return _dl_catch_error (objname, errstring, mallocedp, operate, args);

+}

+

 #endif /* DL_ERROR_BOOTSTRAP */

diff --git a/elf/rtld.c b/elf/rtld.c

index 461d8c114a875a9b..c445b5ca25dea193 100644

--- a/elf/rtld.c

+++ b/elf/rtld.c

@@ -365,6 +365,7 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =

     ._dl_lookup_symbol_x = _dl_lookup_symbol_x,

     ._dl_open = _dl_open,

     ._dl_close = _dl_close,

+    ._dl_catch_error = _rtld_catch_error,

     ._dl_tls_get_addr_soft = _dl_tls_get_addr_soft,

 #ifdef HAVE_DL_DISCOVER_OSVERSION

     ._dl_discover_osversion = _dl_discover_osversion

diff --git a/elf/tst-dlmopen-dlerror-mod.c b/elf/tst-dlmopen-dlerror-mod.c

new file mode 100644

index 0000000000000000..7e95dcdeacf005be

--- /dev/null

+++ b/elf/tst-dlmopen-dlerror-mod.c

@@ -0,0 +1,41 @@

+/* Check that dlfcn errors are reported properly after dlmopen.  Test module.

+   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

+   <http://www.gnu.org/licenses/>.  */

+

+#include <dlfcn.h>

+#include <stddef.h>

+#include <support/check.h>

+

+/* Note: This object is not linked into the main program, so we cannot

+   use delayed test failure reporting via TEST_VERIFY etc., and have

+   to use FAIL_EXIT1 (or something else that calls exit).  */

+

+void

+call_dlsym (void)

+{

+  void *ptr = dlsym (NULL, "does not exist");

+  if (ptr != NULL)

+    FAIL_EXIT1 ("dlsym did not fail as expected");

+}

+

+void

+call_dlopen (void)

+{

+  void *handle = dlopen ("tst-dlmopen-dlerror does not exist", RTLD_NOW);

+  if (handle != NULL)

+    FAIL_EXIT1 ("dlopen did not fail as expected");

+}

diff --git a/elf/tst-dlmopen-dlerror.c b/elf/tst-dlmopen-dlerror.c

new file mode 100644

index 0000000000000000..e864d2fe4c3484ab

--- /dev/null

+++ b/elf/tst-dlmopen-dlerror.c

@@ -0,0 +1,37 @@

+/* Check that dlfcn errors are reported properly after dlmopen.

+   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

+   <http://www.gnu.org/licenses/>.  */

+

+#include <stddef.h>

+#include <support/check.h>

+#include <support/xdlfcn.h>

+

+static int

+do_test (void)

+{

+  void *handle = xdlmopen (LM_ID_NEWLM, "tst-dlmopen-dlerror-mod.so",

+                           RTLD_NOW);

+  void (*call_dlsym) (void) = xdlsym (handle, "call_dlsym");

+  void (*call_dlopen) (void) = xdlsym (handle, "call_dlopen");

+

+  call_dlsym ();

+  call_dlopen ();

+

+  return 0;

+}

+

+#include <support/test-driver.c>

diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h

index 7b0a667629ddc06a..d6d02aa3ccffba33 100644

--- a/sysdeps/generic/ldsodefs.h

+++ b/sysdeps/generic/ldsodefs.h

@@ -647,6 +647,12 @@ struct rtld_global_ro

   void *(*_dl_open) (const char *file, int mode, const void *caller_dlopen,

 		     Lmid_t nsid, int argc, char *argv[], char *env[]);

   void (*_dl_close) (void *map);

+  /* libdl in a secondary namespace (after dlopen) must use

+     _dl_catch_error from the main namespace, so it has to be

+     exported in some way.  */

+  int (*_dl_catch_error) (const char **objname, const char **errstring,

+			  bool *mallocedp, void (*operate) (void *),

+			  void *args);

   void *(*_dl_tls_get_addr_soft) (struct link_map *);

 #ifdef HAVE_DL_DISCOVER_OSVERSION

   int (*_dl_discover_osversion) (void);

@@ -889,6 +895,9 @@ extern int _dl_catch_error (const char **objname, const char **errstring,

 			    void *args);

 libc_hidden_proto (_dl_catch_error)

+/* Used for initializing GLRO (_dl_catch_error).  */

+extern __typeof__ (_dl_catch_error) _rtld_catch_error attribute_hidden;

+

 /* Call OPERATE (ARGS).  If no error occurs, set *EXCEPTION to zero.

    Otherwise, store a copy of the raised exception in *EXCEPTION,

    which has to be freed by _dl_exception_free.  As a special case, if