| Message ID | 874l40a3dw.fsf@oldenburg2.str.redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | dlfcn: Failures after dlmopen should not terminate process [BZ #24772] | expand |
Sorry, there was a C&P issue in the test case.
The follow-up fix I will post hopefully shortly should include a more
comprehensive test case, also including dlerror calls.
Thanks,
Florian
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.
2019-07-05 Florian Weimer <fweimer@redhat.com>
[BZ #24772]
* dlfcn/dlerror.c (_dlerror_run): Call _dl_catch_error from the
base namespace, via GLRO (dl_catch_error).
* elf/Makefile [$(build-shared)] (tests): Add tst-dlmopen-dlerror.
(modules-names): Add tst-dlmopen-dlerror-mod.
(tst-dlmopen-dlerror): Link with -ldl.
(tst-dlmopen-dlerror-mod.so): Link with -ldl and libsupport.a.
(tst-dlmopen-dlerror.out): Depend on tst-dlmopen-dlerror-mod.so.
* elf/dl-error-skeleton.c [DL_ERROR_BOOTSTRAP]
(_rtld_catch_error): Define.
* elf/rtld.c (_rtld_global_ro): Initialize _dl_catch_error.
* elf/tst-dlmopen-dlerror-mod.c: New file.
* elf/tst-dlmopen-dlerror.c: Likewise.
* sysdeps/generic/ldsodefs.h (struct rtld_global_ro): Add
_dl_catch_error member.
(_rtld_catch_error): Declare.
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c
index ca42c126c1..c2b08c7fc4 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 a3eefd1b1f..b8dd5b30db 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -192,7 +192,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \
tst-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note \
tst-unwind-ctor tst-unwind-main tst-audit13 \
- tst-sonamemove-link tst-sonamemove-dlopen
+ tst-sonamemove-link tst-sonamemove-dlopen tst-dlmopen-dlerror
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -283,7 +283,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib \
tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib \
tst-audit13mod1 tst-sonamemove-linkmod1 \
- tst-sonamemove-runmod1 tst-sonamemove-runmod2
+ tst-sonamemove-runmod1 tst-sonamemove-runmod2 \
+ tst-dlmopen-dlerror-mod
# Most modules build with _ISOMAC defined, but those filtered out
# depend on internal headers.
modules-names-tests = $(filter-out ifuncmod% tst-libc_dlvsym-dso tst-tlsmod%,\
@@ -1434,6 +1435,10 @@ $(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 248c185a74..5c2b1d4fb7 100644
--- a/elf/dl-error-skeleton.c
+++ b/elf/dl-error-skeleton.c
@@ -236,4 +236,16 @@ _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 c9490ff694..ba2323baa1 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -325,6 +325,7 @@ 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 0000000000..dcb94320b4
--- /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) 2019 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 0000000000..65638f7f38
--- /dev/null
+++ b/elf/tst-dlmopen-dlerror.c
@@ -0,0 +1,37 @@
+/* Check that dlfcn errors are reported properly after dlmopen.
+ Copyright (C) 2019 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 b1fc5c31f9..c8894e9518 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -604,6 +604,12 @@ 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);
@@ -841,6 +847,9 @@ 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. */
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c index ca42c126c1..c2b08c7fc4 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 a3eefd1b1f..b8dd5b30db 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -192,7 +192,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \ tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \ tst-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note \ tst-unwind-ctor tst-unwind-main tst-audit13 \ - tst-sonamemove-link tst-sonamemove-dlopen + tst-sonamemove-link tst-sonamemove-dlopen tst-dlmopen-dlerror # reldep9 tests-internal += loadtest unload unload2 circleload1 \ neededtest neededtest2 neededtest3 neededtest4 \ @@ -283,7 +283,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \ tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib \ tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib \ tst-audit13mod1 tst-sonamemove-linkmod1 \ - tst-sonamemove-runmod1 tst-sonamemove-runmod2 + tst-sonamemove-runmod1 tst-sonamemove-runmod2 \ + tst-dlmopen-dlerror-mod # Most modules build with _ISOMAC defined, but those filtered out # depend on internal headers. modules-names-tests = $(filter-out ifuncmod% tst-libc_dlvsym-dso tst-tlsmod%,\ @@ -1434,6 +1435,10 @@ $(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 248c185a74..5c2b1d4fb7 100644 --- a/elf/dl-error-skeleton.c +++ b/elf/dl-error-skeleton.c @@ -236,4 +236,16 @@ _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 c9490ff694..ba2323baa1 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -325,6 +325,7 @@ 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 0000000000..dcb94320b4 --- /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) 2019 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 0000000000..0a7c79e709 --- /dev/null +++ b/elf/tst-dlmopen-dlerror.c @@ -0,0 +1,40 @@ +/* Check that dlfcn errors are reported properly after dlmopen. + Copyright (C) 2019 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) +{ + /* tst-sonamemove-runmod1.so does not define moved_function, but it + depends on tst-sonamemove-runmod2.so, which does. */ + void *handle = dlmopen (LM_ID_NEWLM, "tst-dlmopen-dlerror-mod.so", RTLD_NOW); + if (handle == NULL) + FAIL_EXIT1 ("dlmopen: %s", dlerror ()); + 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 b1fc5c31f9..c8894e9518 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -604,6 +604,12 @@ 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); @@ -841,6 +847,9 @@ 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. */
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. (Sorry for the limited test case, otherwise it will run into *another* bug.) 2019-07-05 Florian Weimer <fweimer@redhat.com> [BZ #24772] * dlfcn/dlerror.c (_dlerror_run): Call _dl_catch_error from the base namespace, via GLRO (dl_catch_error). * elf/Makefile [$(build-shared)] (tests): Add tst-dlmopen-dlerror. (modules-names): Add tst-dlmopen-dlerror-mod. (tst-dlmopen-dlerror): Link with -ldl. (tst-dlmopen-dlerror-mod.so): Link with -ldl and libsupport.a. (tst-dlmopen-dlerror.out): Depend on tst-dlmopen-dlerror-mod.so. * elf/dl-error-skeleton.c [DL_ERROR_BOOTSTRAP] (_rtld_catch_error): Define. * elf/rtld.c (_rtld_global_ro): Initialize _dl_catch_error. * elf/tst-dlmopen-dlerror-mod.c: New file. * elf/tst-dlmopen-dlerror.c: Likewise. * sysdeps/generic/ldsodefs.h (struct rtld_global_ro): Add _dl_catch_error member. (_rtld_catch_error): Declare.