From owner-svn-src-head@freebsd.org Mon Aug 24 09:20:25 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 8910B3B727E; Mon, 24 Aug 2020 09:20:25 +0000 (UTC) (envelope-from arichardson@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4BZmn539h8z4SPC; Mon, 24 Aug 2020 09:20:25 +0000 (UTC) (envelope-from arichardson@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 9D16F16431; Mon, 24 Aug 2020 09:20:23 +0000 (UTC) (envelope-from arichardson@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 07O9KNVs003879; Mon, 24 Aug 2020 09:20:23 GMT (envelope-from arichardson@FreeBSD.org) Received: (from arichardson@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 07O9KN8j003878; Mon, 24 Aug 2020 09:20:23 GMT (envelope-from arichardson@FreeBSD.org) Message-Id: <202008240920.07O9KN8j003878@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: arichardson set sender to arichardson@FreeBSD.org using -f From: Alex Richardson Date: Mon, 24 Aug 2020 09:20:23 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364647 - head/usr.sbin/crunch/crunchgen X-SVN-Group: head X-SVN-Commit-Author: arichardson X-SVN-Commit-Paths: head/usr.sbin/crunch/crunchgen X-SVN-Commit-Revision: 364647 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Aug 2020 09:20:25 -0000 Author: arichardson Date: Mon Aug 24 09:20:23 2020 New Revision: 364647 URL: https://svnweb.freebsd.org/changeset/base/364647 Log: Correctly determine the real executable in crunched binaries This should fix cases like su setting argv[0] to _su for /bin/sh. Previously cheribsdbox (a crunched tool we use in CheriBSD to reduce the size of our minimal disk images to allow loading them onto FPGAs without waiting forever for the transfer) would complain about _su not being compiled in, but now that we also look at AT_EXECPATH it correctly invokes the sh tool. Note: we use use AT_EXECPATH instead of the KERN_PROC_PATHNAME sysctl to get the crunchgen binary name since it seems like KERN_PROC_PATHNAME just returns the last cached path for a given hardlink. When using `su`, instead of invoking /bin/csh this would invoke the last used hardlink to cheribsdbox. This caused weird test failures when running tests due to `id` being executed instead of `echo`: $ id # id is a hardlink to /bin/cheribsdbox $ su postgres -c 'echo 1' # su is also a hardlink uid=1001(postgres) gid=1001(postgres) groups=1001(postgres) Obtained from: CheriBSD Reviewed By: emaste, brooks Differential Revision: https://reviews.freebsd.org/D25998 Modified: head/usr.sbin/crunch/crunchgen/crunched_main.c Modified: head/usr.sbin/crunch/crunchgen/crunched_main.c ============================================================================== --- head/usr.sbin/crunch/crunchgen/crunched_main.c Mon Aug 24 09:20:18 2020 (r364646) +++ head/usr.sbin/crunch/crunchgen/crunched_main.c Mon Aug 24 09:20:23 2020 (r364647) @@ -23,6 +23,38 @@ * Computer Science Department * University of Maryland at College Park */ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright 2020 Alex Richardson + * + * This software was developed by SRI International and the University of + * Cambridge Computer Laboratory (Department of Computer Science and + * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the + * DARPA SSITH research programme. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + */ /* * crunched_main.c - main program for crunched binaries, it branches to a * particular subprogram based on the value of argv[0]. Also included @@ -35,6 +67,11 @@ #include __FBSDID("$FreeBSD$"); +#include +#include +#include + +#include #include #include #include @@ -44,30 +81,88 @@ struct stub { int (*f)(); }; -extern char *__progname; +extern const char *__progname; extern struct stub entry_points[]; static void crunched_usage(void); +static struct stub * +find_entry_point(const char *basename) +{ + struct stub *ep = NULL; + + for (ep = entry_points; ep->name != NULL; ep++) + if (!strcmp(basename, ep->name)) + break; + + return (ep); +} + +static const char * +get_basename(const char *exe_path) +{ + const char *slash = strrchr(exe_path, '/'); + return (slash ? slash + 1 : exe_path); +} + int main(int argc, char **argv, char **envp) { - char *slash, *basename; - struct stub *ep; + struct stub *ep = NULL; + const char *basename = NULL; - if (argv[0] == NULL || *argv[0] == '\0') - crunched_usage(); + /* + * Look at __progname first (this will be set if the crunched binary is + * invoked directly). + */ + if (__progname) { + basename = get_basename(__progname); + ep = find_entry_point(basename); + } - slash = strrchr(argv[0], '/'); - basename = slash ? slash + 1 : argv[0]; + /* + * Otherwise try to find entry point based on argv[0] (this works for + * both symlinks as well as hardlinks). However, it does not work when + * su invokes a crunched shell because it sets argv[0] to _su when + * invoking the shell. In that case we look at AT_EXECPATH as a + * fallback. + */ + if (ep == NULL) { + basename = get_basename(argv[0]); + ep = find_entry_point(basename); + } - for (ep = entry_points; ep->name != NULL; ep++) - if (!strcmp(basename, ep->name)) - break; + /* + * If we didn't find the entry point based on __progname or argv[0], + * try AT_EXECPATH to get the actual binary that was executed. + */ + if (ep == NULL) { + char buf[MAXPATHLEN]; + int error = elf_aux_info(AT_EXECPATH, &buf, sizeof(buf)); - if (ep->name) + if (error == 0) { + const char *exe_name = get_basename(buf); + /* + * Keep using argv[0] if AT_EXECPATH is the crunched + * binary so that symlinks to the crunched binary report + * "not compiled in" instead of invoking + * crunched_main(). + */ + if (strcmp(exe_name, EXECNAME) != 0) { + basename = exe_name; + ep = find_entry_point(basename); + } + } else { + warnc(error, "elf_aux_info(AT_EXECPATH) failed"); + } + } + + if (basename == NULL || *basename == '\0') + crunched_usage(); + + if (ep != NULL) { return ep->f(argc, argv, envp); - else { + } else { fprintf(stderr, "%s: %s not compiled in\n", EXECNAME, basename); crunched_usage(); } @@ -76,16 +171,10 @@ main(int argc, char **argv, char **envp) int crunched_main(int argc, char **argv, char **envp) { - char *slash; - struct stub *ep; - int columns, len; - if (argc <= 1) crunched_usage(); - slash = strrchr(argv[1], '/'); - __progname = slash ? slash + 1 : argv[1]; - + __progname = get_basename(argv[1]); return main(--argc, ++argv, envp); }