ld.so: command argument "--preload"
Commit Message
On 6/11/18 11:14 pm, Florian Weimer wrote:
> Don't forget to verify that the test works even if you configure glibc
> with --enable-hardcoded-path-in-tests. If not, we can disable the test
> in this case.
I've done all that.
Here's a patch that adds --preload to rtld, and includes a test that
works with or without --enable-hardcoded-path-in-tests.
By the way, is this a list which permits MIME attachments?
----8<--------8<--------8<--------8<--------8<--------8<--------8<--------8<--
Comments
* David Newall:
> On 6/11/18 11:14 pm, Florian Weimer wrote:
>> Don't forget to verify that the test works even if you configure glibc
>> with --enable-hardcoded-path-in-tests. If not, we can disable the test
>> in this case.
>
> I've done all that.
>
> Here's a patch that adds --preload to rtld, and includes a test that
> works with or without --enable-hardcoded-path-in-tests.
>
> By the way, is this a list which permits MIME attachments?
Yes, as long as it's not text/html. Please resend your patch as an
attachment; it looks like some lines were wrapped.
Thanks,
Florian
@@ -353,7 +353,8 @@ endif
ifeq (yes,$(build-shared))
ifeq ($(run-built-tests),yes)
-tests-special += $(objpfx)tst-pathopt.out $(objpfx)tst-rtld-load-self.out
+tests-special += $(objpfx)tst-pathopt.out $(objpfx)tst-rtld-load-self.out \
+ $(objpfx)tst-rtld-preload.out
endif
tests-special += $(objpfx)check-textrel.out $(objpfx)check-execstack.out \
$(objpfx)check-localplt.out $(objpfx)check-initfini.out
@@ -882,6 +883,13 @@ $(objpfx)tst-rtld-load-self.out: tst-rtld-load-self.sh $(objpfx)ld.so
$(SHELL) $^ '$(test-wrapper)' '$(test-wrapper-env)' > $@; \
$(evaluate-test)
+tst-rtld-preload-OBJS = $(subst $(empty) ,:,$(strip $(preloadtest-preloads:=.so)))
+$(objpfx)tst-rtld-preload.out: tst-rtld-preload.sh $(objpfx)ld.so \
+ $(objpfx)preloadtest
+ $(SHELL) $^ '$(test-wrapper)' '$(test-wrapper-env)' '$(run_program_env)' \
+ '$(rpath-link)' '$(tst-rtld-preload-OBJS)' > $@; \
+ $(evaluate-test)
+
$(objpfx)initfirst: $(libdl)
$(objpfx)initfirst.out: $(objpfx)firstobj.so
@@ -826,6 +826,8 @@ static const char *library_path attribute_relro;
static const char *preloadlist attribute_relro;
/* Nonzero if information about versions has to be printed. */
static int version_info attribute_relro;
+/* The preload list passed as a command argument. */
+static const char *preloadarg attribute_relro;
/* The LD_PRELOAD environment variable gives list of libraries
separated by white space or colons that are loaded before the
@@ -833,8 +835,9 @@ static int version_info attribute_relro;
(If the binary is running setuid all elements containing a '/' are
ignored since it is insecure.) Return the number of preloads
performed. */
+/* Ditto for --preload command argument */
unsigned int
-handle_ld_preload (const char *preloadlist, struct link_map *main_map)
+handle_preload_list (const char *preloadlist, struct link_map *main_map, const char *where)
{
unsigned int npreloads = 0;
const char *p = preloadlist;
@@ -858,7 +861,7 @@ handle_ld_preload (const char *preloadlist, struct link_map *main_map)
++p;
if (dso_name_valid_for_suid (fname))
- npreloads += do_preload (fname, main_map, "LD_PRELOAD");
+ npreloads += do_preload (fname, main_map, where);
}
return npreloads;
}
@@ -978,6 +981,13 @@ dl_main (const ElfW(Phdr) *phdr,
_dl_argc -= 2;
_dl_argv += 2;
}
+ else if (! strcmp(_dl_argv[1], "--preload") && _dl_argc > 2)
+ {
+ preloadarg = _dl_argv[2];
+ _dl_skip_args += 2;
+ _dl_argc -= 2;
+ _dl_argv += 2;
+ }
else
break;
@@ -1006,7 +1016,8 @@ of this helper program; chances are you did not intend to run this program.\n\
variable LD_LIBRARY_PATH\n\
--inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
in LIST\n\
- --audit LIST use objects named in LIST as auditors\n");
+ --audit LIST use objects named in LIST as auditors\n\
+ --preload LIST preload objects named in LIST\n");
++_dl_skip_args;
--_dl_argc;
@@ -1620,7 +1631,16 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
if (__glibc_unlikely (preloadlist != NULL))
{
HP_TIMING_NOW (start);
- npreloads += handle_ld_preload (preloadlist, main_map);
+ npreloads += handle_preload_list (preloadlist, main_map, "LD_PRELOAD");
+ HP_TIMING_NOW (stop);
+ HP_TIMING_DIFF (diff, start, stop);
+ HP_TIMING_ACCUM_NT (load_time, diff);
+ }
+
+ if (__glibc_unlikely (preloadarg != NULL))
+ {
+ HP_TIMING_NOW (start);
+ npreloads += handle_preload_list (preloadarg, main_map, "--preload");
HP_TIMING_NOW (stop);
HP_TIMING_DIFF (diff, start, stop);
HP_TIMING_ACCUM_NT (load_time, diff);
new file mode 100755
@@ -0,0 +1,37 @@
+#!/bin/sh
+# Test how rtld loads itself.
+# Copyright (C) 2012-2016 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
+#. + +set -e + +rtld=$1 +test_program=$2 +test_wrapper=$3
+test_wrapper_env=$4 +run_program_env=$5 +library_path=$6 +preload=$7 +
+echo "# [${test_wrapper}] [$rtld] [--library-path] [$library_path]
[--preload] [$preload] [$test_program]" +${test_wrapper_env} \
+${run_program_env} \ +${test_wrapper} $rtld --library-path
$library_path --preload $preload $test_program 2>&1 && rc=0 || rc=$?
+echo "# exit status $rc" + +exit $rc