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elf: Implement --preload option for the dynamic linker
This commit is contained in:
David Newall
Florian Weimer
parent
5e10136b3c
commit
8692ebdb12
13
ChangeLog
13
ChangeLog
@ -1,3 +1,16 @@
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2019-02-04 David Newall <glibc@davidnewall.com>
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elf: Implement --preload option for the dynamic linker.
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* elf/rtld.c (preloadarg): New variable.
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(handle_preload_list): Pass through “where” argument to
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do_preload.
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(dl_main): Handle "--preload" and add second call to
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handle_preload_list.
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* elf/Makefile (tests-special): Add tst-rtld-preload.out.
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(tst-rtld-preload-OBJS): Set variable.
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(tst-rtld-preload.out): New target.
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* elf/tst-rtld-preload.sh: New file.
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2019-02-04 Matthew Malcomson <matthew.malcomson@arm.com>
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* Makefile (testrun.sh): Exit in case of incorrect argument.
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3
NEWS
3
NEWS
@ -9,7 +9,8 @@ Version 2.30
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Major new features:
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[Add new features here]
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* The dynamic linker accepts the --preload argument to preload shared
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objects, in addition to the LD_PRELOAD environment variable.
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Deprecated and removed features, and other changes affecting compatibility:
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12
elf/Makefile
12
elf/Makefile
@ -354,7 +354,8 @@ endif
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ifeq (yes,$(build-shared))
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ifeq ($(run-built-tests),yes)
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tests-special += $(objpfx)tst-pathopt.out $(objpfx)tst-rtld-load-self.out
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tests-special += $(objpfx)tst-pathopt.out $(objpfx)tst-rtld-load-self.out \
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$(objpfx)tst-rtld-preload.out
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endif
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tests-special += $(objpfx)check-textrel.out $(objpfx)check-execstack.out \
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$(objpfx)check-localplt.out $(objpfx)check-initfini.out
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@ -883,6 +884,15 @@ $(objpfx)tst-rtld-load-self.out: tst-rtld-load-self.sh $(objpfx)ld.so
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$(SHELL) $^ '$(test-wrapper)' '$(test-wrapper-env)' > $@; \
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$(evaluate-test)
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tst-rtld-preload-OBJS = $(subst $(empty) ,:,$(strip $(preloadtest-preloads:=.so)))
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$(objpfx)tst-rtld-preload.out: tst-rtld-preload.sh $(objpfx)ld.so \
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$(objpfx)preloadtest \
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$(preloadtest-preloads:%=$(objpfx)%.so)
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$(SHELL) $< $(objpfx)ld.so $(objpfx)preloadtest \
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'$(test-wrapper)' '$(test-wrapper-env)' '$(run_program_env)' \
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'$(rpath-link)' '$(tst-rtld-preload-OBJS)' > $@; \
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$(evaluate-test)
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$(objpfx)initfirst: $(libdl)
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$(objpfx)initfirst.out: $(objpfx)firstobj.so
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30
elf/rtld.c
30
elf/rtld.c
@ -826,15 +826,18 @@ static const char *library_path attribute_relro;
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static const char *preloadlist attribute_relro;
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/* Nonzero if information about versions has to be printed. */
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static int version_info attribute_relro;
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/* The preload list passed as a command argument. */
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static const char *preloadarg attribute_relro;
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/* The LD_PRELOAD environment variable gives list of libraries
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separated by white space or colons that are loaded before the
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executable's dependencies and prepended to the global scope list.
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(If the binary is running setuid all elements containing a '/' are
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ignored since it is insecure.) Return the number of preloads
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performed. */
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performed. Ditto for --preload command argument. */
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unsigned int
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handle_ld_preload (const char *preloadlist, struct link_map *main_map)
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handle_preload_list (const char *preloadlist, struct link_map *main_map,
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const char *where)
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{
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unsigned int npreloads = 0;
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const char *p = preloadlist;
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@ -858,7 +861,7 @@ handle_ld_preload (const char *preloadlist, struct link_map *main_map)
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++p;
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if (dso_name_valid_for_suid (fname))
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npreloads += do_preload (fname, main_map, "LD_PRELOAD");
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npreloads += do_preload (fname, main_map, where);
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}
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return npreloads;
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}
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@ -974,6 +977,13 @@ dl_main (const ElfW(Phdr) *phdr,
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{
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process_dl_audit (_dl_argv[2]);
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_dl_skip_args += 2;
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_dl_argc -= 2;
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_dl_argv += 2;
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}
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else if (! strcmp (_dl_argv[1], "--preload") && _dl_argc > 2)
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{
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preloadarg = _dl_argv[2];
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_dl_skip_args += 2;
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_dl_argc -= 2;
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_dl_argv += 2;
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@ -1006,7 +1016,8 @@ of this helper program; chances are you did not intend to run this program.\n\
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variable LD_LIBRARY_PATH\n\
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--inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
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in LIST\n\
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--audit LIST use objects named in LIST as auditors\n");
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--audit LIST use objects named in LIST as auditors\n\
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--preload LIST preload objects named in LIST\n");
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++_dl_skip_args;
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--_dl_argc;
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@ -1620,7 +1631,16 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
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if (__glibc_unlikely (preloadlist != NULL))
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{
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HP_TIMING_NOW (start);
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npreloads += handle_ld_preload (preloadlist, main_map);
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npreloads += handle_preload_list (preloadlist, main_map, "LD_PRELOAD");
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HP_TIMING_NOW (stop);
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HP_TIMING_DIFF (diff, start, stop);
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HP_TIMING_ACCUM_NT (load_time, diff);
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}
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if (__glibc_unlikely (preloadarg != NULL))
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{
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HP_TIMING_NOW (start);
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npreloads += handle_preload_list (preloadarg, main_map, "--preload");
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HP_TIMING_NOW (stop);
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HP_TIMING_DIFF (diff, start, stop);
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HP_TIMING_ACCUM_NT (load_time, diff);
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38
elf/tst-rtld-preload.sh
Executable file
38
elf/tst-rtld-preload.sh
Executable file
@ -0,0 +1,38 @@
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#!/bin/sh
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# Test --preload argument ld.so.
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# Copyright (C) 2019 Free Software Foundation, Inc.
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# This file is part of the GNU C Library.
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#
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# The GNU C Library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# The GNU C Library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with the GNU C Library; if not, see
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# <http://www.gnu.org/licenses/>.
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set -e
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rtld=$1
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test_program=$2
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test_wrapper=$3
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test_wrapper_env=$4
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run_program_env=$5
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library_path=$6
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preload=$7
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echo "# [${test_wrapper}] [$rtld] [--library-path] [$library_path]" \
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"[--preload] [$preload] [$test_program]"
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${test_wrapper_env} \
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${run_program_env} \
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${test_wrapper} $rtld --library-path "$library_path" \
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--preload "$preload" $test_program 2>&1 && rc=0 || rc=$?
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echo "# exit status $rc"
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exit $rc
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