commit f0b2132b35248c1f4a80f62a2c38cddcc802aa8c

Author: Florian Weimer <fweimer@redhat.com>

Date:   Fri Jun 28 10:12:50 2019 +0200

    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.

Conflicts:

	elf/Makefile

	  (usual missing backports)

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

index 29aa3a96738e4176..73f9e25ea5efd63a 100644

--- a/elf/Makefile

+++ b/elf/Makefile

@@ -187,7 +187,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \

 	 tst-tlsalign tst-tlsalign-extern tst-nodelete-opened \

 	 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-debug1 tst-main1 tst-absolute-sym tst-absolute-zero tst-big-note \

+	 tst-sonamemove-link tst-sonamemove-dlopen

 #	 reldep9

 tests-internal += loadtest unload unload2 circleload1 \

 	 neededtest neededtest2 neededtest3 neededtest4 \

@@ -275,7 +276,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \

 		tst-latepthreadmod $(tst-tls-many-dynamic-modules) \

 		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-absolute-zero-lib tst-big-note-lib \

+		tst-sonamemove-linkmod1 \

+		tst-sonamemove-runmod1 tst-sonamemove-runmod2

 ifeq (yes,$(have-mtls-dialect-gnu2))

 tests += tst-gnu2-tls1

@@ -1374,6 +1377,28 @@ tst-audit12-ENV = LD_AUDIT=$(objpfx)tst-auditmod12.so

 $(objpfx)tst-audit12mod1.so: $(objpfx)tst-audit12mod2.so

 LDFLAGS-tst-audit12mod2.so = -Wl,--version-script=tst-audit12mod2.map

+# 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 = \

diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c

index 68ecc6179f608547..1d046caf017b582b 100644

--- a/elf/dl-lookup.c

+++ b/elf/dl-lookup.c

@@ -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))

     {

diff --git a/elf/tst-sonamemove-dlopen.c b/elf/tst-sonamemove-dlopen.c

new file mode 100644

index 0000000000000000..c496705044cdd53c

--- /dev/null

+++ b/elf/tst-sonamemove-dlopen.c

@@ -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>

diff --git a/elf/tst-sonamemove-link.c b/elf/tst-sonamemove-link.c

new file mode 100644

index 0000000000000000..4bc3bf32f88f97a9

--- /dev/null

+++ b/elf/tst-sonamemove-link.c

@@ -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>

diff --git a/elf/tst-sonamemove-linkmod1.c b/elf/tst-sonamemove-linkmod1.c

new file mode 100644

index 0000000000000000..b8a354e5e394f566

--- /dev/null

+++ b/elf/tst-sonamemove-linkmod1.c

@@ -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)

+{

+}

diff --git a/elf/tst-sonamemove-linkmod1.map b/elf/tst-sonamemove-linkmod1.map

new file mode 100644

index 0000000000000000..8fe5904018972009

--- /dev/null

+++ b/elf/tst-sonamemove-linkmod1.map

@@ -0,0 +1,3 @@

+SONAME_MOVE {

+  global: moved_function;

+};

diff --git a/elf/tst-sonamemove-runmod1.c b/elf/tst-sonamemove-runmod1.c

new file mode 100644

index 0000000000000000..5c409e22898bc836

--- /dev/null

+++ b/elf/tst-sonamemove-runmod1.c

@@ -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)

+{

+}

diff --git a/elf/tst-sonamemove-runmod1.map b/elf/tst-sonamemove-runmod1.map

new file mode 100644

index 0000000000000000..2ea81c6e6ffae2be

--- /dev/null

+++ b/elf/tst-sonamemove-runmod1.map

@@ -0,0 +1,3 @@

+SONAME_MOVE {

+  global: other_function;

+};

diff --git a/elf/tst-sonamemove-runmod2.c b/elf/tst-sonamemove-runmod2.c

new file mode 100644

index 0000000000000000..b5e482eff57d7d83

--- /dev/null

+++ b/elf/tst-sonamemove-runmod2.c

@@ -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)

+{

+}

diff --git a/elf/tst-sonamemove-runmod2.map b/elf/tst-sonamemove-runmod2.map

new file mode 100644

index 0000000000000000..8fe5904018972009

--- /dev/null

+++ b/elf/tst-sonamemove-runmod2.map

@@ -0,0 +1,3 @@

+SONAME_MOVE {

+  global: moved_function;

+};