commit f4cba6ca1e5ff2c229af6d474c3ef2c0df2fae52
Author: Florian Weimer <fweimer@redhat.com>
Date: Wed Apr 21 19:49:51 2021 +0200
dlfcn: Failures after dlmopen should not terminate process [BZ #15271]
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.
Backport notes: GLRO (dl_catch_error) is replaced with
_dl_catch_error_ptr to preserve _rtld_global_ro layout.
(cherry picked from commit b2964eb1d9a6b8ab1250e8a881cf406182da5875)
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c
index 48b4c25bead9f0c8..ff7c7b9228c4a6d8 100644
--- a/dlfcn/dlerror.c
+++ b/dlfcn/dlerror.c
@@ -167,8 +167,17 @@ _dlerror_run (void (*operate) (void *), void *args)
result->errstring = NULL;
}
- result->errcode = _dl_catch_error (&result->objname, &result->errstring,
- &result->malloced, operate, args);
+#ifdef SHARED
+ result->errcode = _dl_catch_error_ptr (&result->objname,
+ &result->errstring,
+ &result->malloced,
+ operate, args);
+#else
+ result->errcode = _dl_catch_error (&result->objname,
+ &result->errstring,
+ &result->malloced,
+ operate, args);
+#endif
/* 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 28e18aea5d412222..509475dd9914e6f3 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -226,7 +226,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-audit14 tst-audit15 tst-audit16 \
tst-single_threaded tst-single_threaded-pthread \
tst-tls-ie tst-tls-ie-dlmopen argv0test \
- tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask
+ tst-glibc-hwcaps tst-glibc-hwcaps-prepend tst-glibc-hwcaps-mask \
+ tst-dlmopen-dlerror
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -348,6 +349,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
libmarkermod2-1 libmarkermod2-2 \
libmarkermod3-1 libmarkermod3-2 libmarkermod3-3 \
libmarkermod4-1 libmarkermod4-2 libmarkermod4-3 libmarkermod4-4 \
+ tst-dlmopen-dlerror-mod \
# Most modules build with _ISOMAC defined, but those filtered out
# depend on internal headers.
@@ -1583,6 +1585,10 @@ $(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/Versions b/elf/Versions
index be88c48e6d45a937..cdfd7b4d2f0c6a12 100644
--- a/elf/Versions
+++ b/elf/Versions
@@ -72,7 +72,7 @@ ld {
# Internal error handling support. Interposed by libc.so.
_dl_signal_exception; _dl_catch_exception;
- _dl_signal_error; _dl_catch_error;
+ _dl_signal_error; _dl_catch_error; _dl_catch_error_ptr;
# Set value of a tunable.
__tunable_get_val;
diff --git a/elf/dl-error-skeleton.c b/elf/dl-error-skeleton.c
index 2fd62777cfc4f34d..0de505f2584612e0 100644
--- a/elf/dl-error-skeleton.c
+++ b/elf/dl-error-skeleton.c
@@ -248,4 +248,19 @@ _dl_receive_error (receiver_fct fct, void (*operate) (void *), void *args)
catch_hook = old_catch;
receiver = old_receiver;
}
+
+/* Forwarder used for initializing _dl_catch_error_ptr. */
+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);
+}
+
+__typeof (_dl_catch_error) *_dl_catch_error_ptr = _rtld_catch_error;
+rtld_hidden_data_def (_dl_catch_error_ptr);
+
#endif /* DL_ERROR_BOOTSTRAP */
diff --git a/elf/rtld.c b/elf/rtld.c
index 94a00e204907bff7..489e58c551890023 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -380,7 +380,6 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
extern struct rtld_global_ro _rtld_local_ro
__attribute__ ((alias ("_rtld_global_ro"), visibility ("hidden")));
-
static void dl_main (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv);
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 aab7245e9330a782..d552a7886ba8dacf 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -893,6 +893,17 @@ extern int _dl_catch_error (const char **objname, const char **errstring,
void *args);
libc_hidden_proto (_dl_catch_error)
+
+/* 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. Initialized to _rtld_catch_error in rtld.c. Not in
+ _rtld_global_ro to preserve structure layout. */
+extern __typeof (_dl_catch_error) *_dl_catch_error_ptr attribute_relro;
+rtld_hidden_proto (_dl_catch_error_ptr)
+
+/* Used for initializing _dl_catch_error_ptr. */
+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