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ld.so: Support moving versioned symbols between sonames [BZ #24741] 

This change should be fully backwards-compatible because the old
code aborted the load if a soname mismatch was encountered
(instead of searching further for a matching symbol).  This means
that no different symbols are found.

The soname check was explicitly disabled for the skip_map != NULL
case.  However, this only happens with dl(v)sym and RTLD_NEXT,
and those lookups do not come with a verneed entry that could be used
for the check.

The error check was already explicitly disabled for the skip_map !=
NULL case, that is, when dl(v)sym was called with RTLD_NEXT.  But
_dl_vsym always sets filename in the struct r_found_version argument
to NULL, so the check was not active anyway.  This means that
symbol lookup results for the skip_map != NULL case do not change,
either.
This commit is contained in:
Florian Weimer 2019-06-28 10:12:50 +02:00
parent 17432d7150
commit f0b2132b35
12 changed files with 223 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
ChangeLog
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@ -1,3 +1,32 @@
2019-06-28 Florian Weimer <fweimer@redhat.com>
[BZ #24741]
* elf/dl-lookup.c (do_lookup_x): Do not fail if there is a soname
mismatch in a versioned symbol reference.
(_dl_lookup_symbol_x): Do not report soname mismatch failures.
* elf/Makefile [$(build-shared)] (tests): Add tst-sonamemove-link,
tst-sonamemove-dlopen.
(module-names): Add tst-sonamemove-linkmod1,
tst-sonamemove-runmod1, tst-sonamemove-runmod2.
(LDFLAGS-tst-sonamemove-linkmod1.so): Set.
(LDFLAGS-tst-sonamemove-runmod1.so): Likewise.
(LDFLAGS-tst-sonamemove-runmod2.so): Likewise.
(tst-sonamemove-runmod1.so): Link against
tst-sonamemove-runmod2.so.
(tst-sonamemove-link): Link against tst-sonamemove-linkmod1.so.
(tst-sonamemove-link.out): Depend on tst-sonamemove-runmod1.so,
tst-sonamemove-runmod2.so.
(tst-sonamemove-dlopen): Link with -ldl.
(tst-sonamemove-dlopen.out): Likewise.
* elf/tst-sonamemove-link.c: New file.
* elf/tst-sonamemove-dlopen.c: Likewise.
* elf/tst-sonamemove-linkmod1.c: Likewise.
* elf/tst-sonamemove-linkmod1.map: Likewise.
* elf/tst-sonamemove-runmod1.c: Likewise.
* elf/tst-sonamemove-runmod1.map: Likewise.
* elf/tst-sonamemove-runmod2.c: Likewise.
* elf/tst-sonamemove-runmod2.map: Likewise.
2019-06-28 Florian Weimer <fweimer@redhat.com>
* support/xdlfcn.h (xdlvsym): Declare function.

6
NEWS
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@ -34,6 +34,12 @@ Major new features:
pointer subtraction within the allocated object, where results might
overflow the ptrdiff_t type.
* The dynamic linker no longer refuses to load objects which reference
versioned symbols whose implementation has moved to a different soname
since the object has been linked. The old error message, symbol
FUNCTION-NAME, version SYMBOL-VERSION not defined in file DSO-NAME with
link time reference, is gone.
Deprecated and removed features, and other changes affecting compatibility:
* The copy_file_range function fails with ENOSYS if the kernel does not

28
elf/Makefile
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@ -191,7 +191,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-nodelete2 tst-audit11 tst-audit12 tst-dlsym-error tst-noload \
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-unwind-ctor tst-unwind-main tst-audit13 \
tst-sonamemove-link tst-sonamemove-dlopen
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@ -281,7 +282,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
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-audit13mod1 tst-sonamemove-linkmod1 \
tst-sonamemove-runmod1 tst-sonamemove-runmod2
# 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%,\
@ -1410,6 +1412,28 @@ $(objpfx)tst-audit13.out: $(objpfx)tst-audit13mod1.so
LDFLAGS-tst-audit13mod1.so = -Wl,-z,lazy
tst-audit13-ENV = LD_AUDIT=$(objpfx)tst-audit13mod1.so
# tst-sonamemove links against an older implementation of the library.
LDFLAGS-tst-sonamemove-linkmod1.so = \
-Wl,--version-script=tst-sonamemove-linkmod1.map \
-Wl,-soname,tst-sonamemove-runmod1.so
LDFLAGS-tst-sonamemove-runmod1.so = -Wl,--no-as-needed \
-Wl,--version-script=tst-sonamemove-runmod1.map \
-Wl,-soname,tst-sonamemove-runmod1.so
LDFLAGS-tst-sonamemove-runmod2.so = \
-Wl,--version-script=tst-sonamemove-runmod2.map \
-Wl,-soname,tst-sonamemove-runmod2.so
$(objpfx)tst-sonamemove-runmod1.so: $(objpfx)tst-sonamemove-runmod2.so
# Link against the link module, but depend on the run-time modules
# for execution.
$(objpfx)tst-sonamemove-link: $(objpfx)tst-sonamemove-linkmod1.so
$(objpfx)tst-sonamemove-link.out: \
$(objpfx)tst-sonamemove-runmod1.so \
$(objpfx)tst-sonamemove-runmod2.so
$(objpfx)tst-sonamemove-dlopen: $(libdl)
$(objpfx)tst-sonamemove-dlopen.out: \
$(objpfx)tst-sonamemove-runmod1.so \
$(objpfx)tst-sonamemove-runmod2.so
# Override -z defs, so that we can reference an undefined symbol.
# Force lazy binding for the same reason.
LDFLAGS-tst-latepthreadmod.so = \

38
elf/dl-lookup.c
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@ -536,11 +536,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
}
skip:
/* If this current map is the one mentioned in the verneed entry
and we have not found a weak entry, it is a bug. */
if (symidx == STN_UNDEF && version != NULL && version->filename != NULL
&& __glibc_unlikely (_dl_name_match_p (version->filename, map)))
return -1;
;
}
while (++i < n);
@ -810,34 +806,10 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
/* Search the relevant loaded objects for a definition. */
for (size_t start = i; *scope != NULL; start = 0, ++scope)
{
int res = do_lookup_x (undef_name, new_hash, &old_hash, *ref,
&current_value, *scope, start, version, flags,
skip_map, type_class, undef_map);
if (res > 0)
break;
if (__glibc_unlikely (res < 0) && skip_map == NULL)
{
/* Oh, oh. The file named in the relocation entry does not
contain the needed symbol. This code is never reached
for unversioned lookups. */
assert (version != NULL);
const char *reference_name = undef_map ? undef_map->l_name : "";
struct dl_exception exception;
/* XXX We cannot translate the message. */
_dl_exception_create_format
(&exception, DSO_FILENAME (reference_name),
"symbol %s version %s not defined in file %s"
" with link time reference%s",
undef_name, version->name, version->filename,
res == -2 ? " (no version symbols)" : "");
_dl_signal_cexception (0, &exception, N_("relocation error"));
_dl_exception_free (&exception);
*ref = NULL;
return 0;
}
}
if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
&current_value, *scope, start, version, flags,
skip_map, type_class, undef_map) != 0)
break;
if (__glibc_unlikely (current_value.s == NULL))
{

35
elf/tst-sonamemove-dlopen.c Normal file
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@ -0,0 +1,35 @@
/* Check that a moved versioned symbol can be found using dlsym, dlvsym.
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 = xdlopen ("tst-sonamemove-runmod1.so", RTLD_NOW);
TEST_VERIFY (xdlsym (handle, "moved_function") != NULL);
TEST_VERIFY (xdlvsym (handle, "moved_function", "SONAME_MOVE") != NULL);
return 0;
}
#include <support/test-driver.c>

41
elf/tst-sonamemove-link.c Normal file
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@ -0,0 +1,41 @@
/* Check that a versioned symbol can move from one library to another.
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/>. */
/* At link time, moved_function is bound to the symbol version
SONAME_MOVE in tst-sonamemove-runmod1.so, using the
tst-sonamemove-linkmod1.so stub object.
At run time, the process loads the real tst-sonamemove-runmod1.so,
which depends on tst-sonamemove-runmod2.so.
tst-sonamemove-runmod1.so does not define moved_function, but
tst-sonamemove-runmod2.so does.
The net effect is that the versioned symbol
moved_function@SONAME_MOVE moved from the soname
tst-sonamemove-linkmod1.so at link time to the soname
tst-sonamemove-linkmod2.so at run time. */
void moved_function (void);
static int
do_test (void)
{
moved_function ();
return 0;
}
#include <support/test-driver.c>

25
elf/tst-sonamemove-linkmod1.c Normal file
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@ -0,0 +1,25 @@
/* Link interface for (lack of) soname matching in versioned symbol refs.
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/>. */
/* This function moved from tst-sonamemove-runmod1.so. This module is
intended for linking only, to simulate an old application which was
linked against an older version of the library. */
void
moved_function (void)
{
}

3
elf/tst-sonamemove-linkmod1.map Normal file
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@ -0,0 +1,3 @@
SONAME_MOVE {
global: moved_function;
};

23
elf/tst-sonamemove-runmod1.c Normal file
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@ -0,0 +1,23 @@
/* Run-time module whose moved_function moved to a library dependency.
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/>. */
/* Dummy function to add the required symbol version. */
void
other_function (void)
{
}

3
elf/tst-sonamemove-runmod1.map Normal file
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@ -0,0 +1,3 @@
SONAME_MOVE {
global: other_function;
};

24
elf/tst-sonamemove-runmod2.c Normal file
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@ -0,0 +1,24 @@
/* Run-time module with the actual implementation of moved_function.
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/>. */
/* In the test scenario, this function was originally in
tst-sonamemove-runmod1.so. */
void
moved_function (void)
{
}

3
elf/tst-sonamemove-runmod2.map Normal file
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@ -0,0 +1,3 @@
SONAME_MOVE {
global: moved_function;
};