From patchwork Thu Nov 8 12:43:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: David Newall X-Patchwork-Id: 30073 Received: (qmail 68181 invoked by alias); 8 Nov 2018 12:43:48 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 68161 invoked by uid 89); 8 Nov 2018 12:43:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, KAM_SHORT autolearn=ham version=3.3.2 spammy=rc, 10067 X-HELO: hawking.rebel.net.au Subject: [PATCH] ld.so: command argument "--preload" To: Florian Weimer Cc: Carlos O'Donell , libc-alpha@sourceware.org References: <322fb70a-9c0e-100b-4366-dfa7e5134aa5@davidnewall.com> <265bec63-9875-7268-2199-c7e133b2298e@davidnewall.com> <874ldb7gxp.fsf@oldenburg.str.redhat.com> <5f79f366-d687-583f-940c-36c169bd34a9@davidnewall.com> <87sh0eqssf.fsf@oldenburg.str.redhat.com> <8816b7fc-d798-42ee-de51-d1de56e6887c@davidnewall.com> <87zhuljiev.fsf@oldenburg.str.redhat.com> <43265e8e-956a-f895-6c04-8cd6898a8c97@davidnewall.com> <877ehphv2a.fsf@oldenburg.str.redhat.com> <2e1f89d3-9718-50ca-328c-b4b82b1974d4@davidnewall.com> <8736sdhtim.fsf@oldenburg.str.redhat.com> <87va57dekq.fsf@oldenburg.str.redhat.com> From: David Newall Message-ID: Date: Thu, 8 Nov 2018 23:13:38 +1030 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 Mime-Version: 1.0 In-Reply-To: <87va57dekq.fsf@oldenburg.str.redhat.com> Thanks, Florian and Carlos, for your guidance.  This is my patch, relative to master source, as pulled two days ago. diff --git a/elf/Makefile b/elf/Makefile index d72e7b6..bc891b9 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -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 +883,15 @@ $(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 \ + $(preloadtest-preloads:%=$(objpfx)%.so) + $(SHELL) $< $(objpfx)ld.so $(objpfx)preloadtest \ + '$(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 diff --git a/elf/rtld.c b/elf/rtld.c index 1b0c747..11ec55b 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -826,15 +826,18 @@ 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 executable's dependencies and prepended to the global scope list. (If the binary is running setuid all elements containing a '/' are ignored since it is insecure.) Return the number of preloads - performed. */ + 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); diff --git a/elf/tst-rtld-preload.sh b/elf/tst-rtld-preload.sh new file mode 100755 index 0000000..4a6a58d --- /dev/null +++ b/elf/tst-rtld-preload.sh @@ -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