commit eb447b7b4bd6177f876ba9420ad9e048c27bae91
Author: David Kilroy <David.Kilroy@arm.com>
Date: Wed Feb 12 14:28:15 2020 -0300
elf: Allow dlopen of filter object to work [BZ #16272]
There are two fixes that are needed to be able to dlopen filter
objects. First _dl_map_object_deps cannot assume that map will be at
the beginning of l_searchlist.r_list[], as filtees are inserted before
map. Secondly dl_open_worker needs to ensure that filtees get
relocated.
In _dl_map_object_deps:
* avoiding removing relocation dependencies of map by setting
l_reserved to 0 and otherwise processing the rest of the search
list.
* ensure that map remains at the beginning of l_initfini - the list
of things that need initialisation (and destruction). Do this by
splitting the copy up. This may not be required, but matches the
initialization order without dlopen.
Modify dl_open_worker to relocate the objects in new->l_inifini.
new->l_initfini is constructed in _dl_map_object_deps, and lists the
objects that need initialization and destruction. Originally the list
of objects in new->l_next are relocated. All of these objects should
also be included in new->l_initfini (both lists are populated with
dependencies in _dl_map_object_deps). We can't use new->l_prev to pick
up filtees, as during a recursive dlopen from an interposed malloc
call, l->prev can contain objects that are not ready for relocation.
Add tests to verify that symbols resolve to the filtee implementation
when auxiliary and filter objects are used, both as a normal link and
when dlopen'd.
Tested by running the testsuite on x86_64.
# Conflicts:
# elf/Makefile
diff --git a/elf/Makefile b/elf/Makefile
index a52d9b1f6a4364a7..b4b618ce62a9e6df 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -192,7 +192,8 @@ 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-sonamemove-link tst-sonamemove-dlopen tst-initfinilazyfail \
- tst-dlopenfail tst-dlopenfail-2
+ tst-dlopenfail tst-dlopenfail-2 \
+ tst-filterobj tst-filterobj-dlopen tst-auxobj tst-auxobj-dlopen
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -302,7 +303,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-sonamemove-runmod1 tst-sonamemove-runmod2 \
tst-initlazyfailmod tst-finilazyfailmod \
tst-dlopenfailmod1 tst-dlopenfaillinkmod tst-dlopenfailmod2 \
- tst-dlopenfailmod3
+ tst-dlopenfailmod3 \
+ tst-filterobj-flt tst-filterobj-aux tst-filterobj-filtee
ifeq (yes,$(have-mtls-dialect-gnu2))
tests += tst-gnu2-tls1
@@ -1626,3 +1628,15 @@ $(objpfx)tst-dlopen-nodelete-reloc-mod17.so: \
$(objpfx)tst-dlopen-nodelete-reloc-mod15.so \
$(objpfx)tst-dlopen-nodelete-reloc-mod16.so
LDFLAGS-tst-dlopen-nodelete-reloc-mod17.so = -Wl,--no-as-needed
+
+LDFLAGS-tst-filterobj-flt.so = -Wl,--filter=$(objpfx)tst-filterobj-filtee.so
+$(objpfx)tst-filterobj: $(objpfx)tst-filterobj-flt.so
+$(objpfx)tst-filterobj-dlopen: $(libdl)
+$(objpfx)tst-filterobj.out: $(objpfx)tst-filterobj-filtee.so
+$(objpfx)tst-filterobj-dlopen.out: $(objpfx)tst-filterobj-filtee.so
+
+LDFLAGS-tst-filterobj-aux.so = -Wl,--auxiliary=$(objpfx)tst-filterobj-filtee.so
+$(objpfx)tst-auxobj: $(objpfx)tst-filterobj-aux.so
+$(objpfx)tst-auxobj-dlopen: $(libdl)
+$(objpfx)tst-auxobj.out: $(objpfx)tst-filterobj-filtee.so
+$(objpfx)tst-auxobj-dlopen.out: $(objpfx)tst-filterobj-filtee.so
diff --git a/elf/dl-deps.c b/elf/dl-deps.c
index 9d9b1ba7f244348a..50f053a1586efdc3 100644
--- a/elf/dl-deps.c
+++ b/elf/dl-deps.c
@@ -485,14 +485,18 @@ _dl_map_object_deps (struct link_map *map,
map->l_searchlist.r_list = &l_initfini[nlist + 1];
map->l_searchlist.r_nlist = nlist;
+ unsigned int map_index = UINT_MAX;
for (nlist = 0, runp = known; runp; runp = runp->next)
{
if (__builtin_expect (trace_mode, 0) && runp->map->l_faked)
/* This can happen when we trace the loading. */
--map->l_searchlist.r_nlist;
- else
+ else {
+ if (runp->map == map)
+ map_index = nlist;
map->l_searchlist.r_list[nlist++] = runp->map;
+ }
/* Now clear all the mark bits we set in the objects on the search list
to avoid duplicates, so the next call starts fresh. */
@@ -550,13 +554,14 @@ Filters not supported with LD_TRACE_PRELINKING"));
}
/* Maybe we can remove some relocation dependencies now. */
- assert (map->l_searchlist.r_list[0] == map);
struct link_map_reldeps *l_reldeps = NULL;
if (map->l_reldeps != NULL)
{
- for (i = 1; i < nlist; ++i)
+ for (i = 0; i < nlist; ++i)
map->l_searchlist.r_list[i]->l_reserved = 1;
+ /* Avoid removing relocation dependencies of the main binary. */
+ map->l_reserved = 0;
struct link_map **list = &map->l_reldeps->list[0];
for (i = 0; i < map->l_reldeps->act; ++i)
if (list[i]->l_reserved)
@@ -581,16 +586,30 @@ Filters not supported with LD_TRACE_PRELINKING"));
}
}
- for (i = 1; i < nlist; ++i)
+ for (i = 0; i < nlist; ++i)
map->l_searchlist.r_list[i]->l_reserved = 0;
}
- /* Sort the initializer list to take dependencies into account. The binary
- itself will always be initialize last. */
- memcpy (l_initfini, map->l_searchlist.r_list,
- nlist * sizeof (struct link_map *));
- /* We can skip looking for the binary itself which is at the front of
- the search list. */
+ /* Sort the initializer list to take dependencies into account. Always
+ initialize the binary itself last. */
+ assert (map_index < nlist);
+ if (map_index > 0)
+ {
+ /* Copy the binary into position 0. */
+ l_initfini[0] = map->l_searchlist.r_list[map_index];
+
+ /* Copy the filtees. */
+ for (i = 0; i < map_index; ++i)
+ l_initfini[i+1] = map->l_searchlist.r_list[i];
+
+ /* Copy the remainder. */
+ for (i = map_index + 1; i < nlist; ++i)
+ l_initfini[i] = map->l_searchlist.r_list[i];
+ }
+ else
+ memcpy (l_initfini, map->l_searchlist.r_list,
+ nlist * sizeof (struct link_map *));
+
_dl_sort_maps (&l_initfini[1], nlist - 1, NULL, false);
/* Terminate the list of dependencies. */
diff --git a/elf/dl-open.c b/elf/dl-open.c
index d834b89754d2b073..d31356f7e17dfb14 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -618,22 +618,25 @@ dl_open_worker (void *a)
allows IFUNC relocations to work and it also means copy
relocation of dependencies are if necessary overwritten. */
unsigned int nmaps = 0;
- struct link_map *l = new;
+ unsigned int j = 0;
+ struct link_map *l = new->l_initfini[0];
do
{
if (! l->l_real->l_relocated)
++nmaps;
- l = l->l_next;
+ l = new->l_initfini[++j];
}
while (l != NULL);
+ /* Stack allocation is limited by the number of loaded objects. */
struct link_map *maps[nmaps];
nmaps = 0;
- l = new;
+ j = 0;
+ l = new->l_initfini[0];
do
{
if (! l->l_real->l_relocated)
maps[nmaps++] = l;
- l = l->l_next;
+ l = new->l_initfini[++j];
}
while (l != NULL);
_dl_sort_maps (maps, nmaps, NULL, false);
diff --git a/elf/tst-auxobj-dlopen.c b/elf/tst-auxobj-dlopen.c
new file mode 100644
index 0000000000000000..cb54aba19470a1fe
--- /dev/null
+++ b/elf/tst-auxobj-dlopen.c
@@ -0,0 +1,47 @@
+/* Test for BZ#16272, dlopen'ing an auxiliary filter object.
+ Ensure that symbols from the resolve correctly.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <support/check.h>
+#include <support/xdlfcn.h>
+
+static int do_test (void)
+{
+ void *lib = xdlopen ("tst-filterobj-aux.so", RTLD_LAZY);
+ char *(*fn)(void) = xdlsym (lib, "get_text");
+ const char* text = fn ();
+
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the filtee */
+ TEST_COMPARE_STRING (text, "Hello from filtee (PASS)");
+
+ fn = xdlsym (lib, "get_text2");
+ text = fn ();
+
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the auxiliary object */
+ TEST_COMPARE_STRING (text, "Hello from auxiliary filter object (PASS)");
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-auxobj.c b/elf/tst-auxobj.c
new file mode 100644
index 0000000000000000..bdc7713b04b4a79b
--- /dev/null
+++ b/elf/tst-auxobj.c
@@ -0,0 +1,42 @@
+/* Test that symbols from auxiliary filter objects are resolved to the
+ filtee.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <support/check.h>
+#include "tst-filterobj-filtee.h"
+
+static int do_test (void)
+{
+ const char* text = get_text ();
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the filtee */
+ TEST_COMPARE_STRING (text, "Hello from filtee (PASS)");
+
+ text = get_text2 ();
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the auxiliary object */
+ TEST_COMPARE_STRING (text, "Hello from auxiliary filter object (PASS)");
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-filterobj-aux.c b/elf/tst-filterobj-aux.c
new file mode 100644
index 0000000000000000..0b732f2fb3a69a7f
--- /dev/null
+++ b/elf/tst-filterobj-aux.c
@@ -0,0 +1,33 @@
+/* Auxiliary filter object.
+ Contains symbols to be resolved in filtee, and one which doesn't.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-filterobj-filtee.h"
+
+/* We never want to see the output of the auxiliary object. */
+const char *get_text (void)
+{
+ return "Hello from auxiliary filter object (FAIL)";
+}
+
+/* The filtee doesn't implement this symbol, so this should resolve. */
+const char *get_text2 (void)
+{
+ return "Hello from auxiliary filter object (PASS)";
+}
diff --git a/elf/tst-filterobj-dlopen.c b/elf/tst-filterobj-dlopen.c
new file mode 100644
index 0000000000000000..c5b5072979802b98
--- /dev/null
+++ b/elf/tst-filterobj-dlopen.c
@@ -0,0 +1,39 @@
+/* Test for BZ#16272, dlopen'ing a filter object.
+ Ensure that symbols from the filter object resolve to the filtee.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <support/check.h>
+#include <support/xdlfcn.h>
+
+static int do_test (void)
+{
+ void *lib = xdlopen ("tst-filterobj-flt.so", RTLD_LAZY);
+ char *(*fn)(void) = xdlsym (lib, "get_text");
+ const char* text = fn ();
+
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the filtee */
+ TEST_COMPARE_STRING (text, "Hello from filtee (PASS)");
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/elf/tst-filterobj-filtee.c b/elf/tst-filterobj-filtee.c
new file mode 100644
index 0000000000000000..8fa557cbd251f53c
--- /dev/null
+++ b/elf/tst-filterobj-filtee.c
@@ -0,0 +1,27 @@
+/* Filtee for BZ#16272 test.
+ Contains desired symbol implementations.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-filterobj-filtee.h"
+
+/* This is the real implementation that wants to be called */
+const char *get_text (void)
+{
+ return "Hello from filtee (PASS)";
+}
diff --git a/elf/tst-filterobj-filtee.h b/elf/tst-filterobj-filtee.h
new file mode 100644
index 0000000000000000..46aee28178b88a77
--- /dev/null
+++ b/elf/tst-filterobj-filtee.h
@@ -0,0 +1,24 @@
+/* Filtee header for BZ#16272 test.
+ Contains prototypes for symbols implemented in the filtee.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+const char *get_text (void);
+
+/* For testing auxiliary filter object. */
+const char *get_text2 (void);
diff --git a/elf/tst-filterobj-flt.c b/elf/tst-filterobj-flt.c
new file mode 100644
index 0000000000000000..5062654be6f14a80
--- /dev/null
+++ b/elf/tst-filterobj-flt.c
@@ -0,0 +1,27 @@
+/* Filter object for BZ#16272 test.
+ Contains symbols to be resolved in filtee.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include "tst-filterobj-filtee.h"
+
+/* We never want to see the output of the filter object */
+const char *get_text (void)
+{
+ return "Hello from filter object (FAIL)";
+}
diff --git a/elf/tst-filterobj.c b/elf/tst-filterobj.c
new file mode 100644
index 0000000000000000..96bfae019ea670bc
--- /dev/null
+++ b/elf/tst-filterobj.c
@@ -0,0 +1,36 @@
+/* Test that symbols from filter objects are resolved to the filtee.
+
+ Copyright (C) 2020 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
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <support/check.h>
+#include "tst-filterobj-filtee.h"
+
+static int do_test (void)
+{
+ const char* text = get_text ();
+
+ printf ("%s\n", text);
+
+ /* Verify the text matches what we expect from the filtee */
+ TEST_COMPARE_STRING (text, "Hello from filtee (PASS)");
+
+ return 0;
+}
+
+#include <support/test-driver.c>