From 8250c5c168f07549ed646e6848e6dda118271e23 Mon Sep 17 00:00:00 2001 From: Daniel Shahaf Date: Thu, 26 Dec 2019 09:16:19 +0000 Subject: Improve PRIVILEGED fixes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit - Fix retval handling in bin_setopt() - Don't skip_setuid / skip_setgid. It's not our place to optimize away noops (that might not even _be_ noops; they might change the saved uid…). - Remove HAVE_* guard checks around functions that are used unguarded elsewhere. - Use bsd-setres_id.c from OpenSSH to provide setresuid() / setresgid() everywhere, and thus simplify the ifdef soup. Fix some preëxisting bugs in the macro definitions of setuid() (do we still need that one?). - Fix zwarning() format codes for variadic arguments type safety - Restored a comment from HEAD - Fix failure modes around initgroups() - Compared privilege restoration code with OpenSSH's permanently_drop_uid() and updated as needed - Add E01 PRIVILEGED sanity checks --- Src/openssh_bsd_setres_id.c | 129 ++++++++++++++++++++++++++++++++++++++ Src/options.c | 148 ++++++++++++++++++++------------------------ Src/zsh.mdd | 3 +- Src/zsh_system.h | 94 +++++++++++++++++++++++----- Test/E01options.ztst | 15 +++++ configure.ac | 5 +- 6 files changed, 292 insertions(+), 102 deletions(-) create mode 100644 Src/openssh_bsd_setres_id.c diff --git a/Src/openssh_bsd_setres_id.c b/Src/openssh_bsd_setres_id.c new file mode 100644 index 000000000..65e91a40c --- /dev/null +++ b/Src/openssh_bsd_setres_id.c @@ -0,0 +1,129 @@ +/* + * Copyright (c) 2012 Darren Tucker (dtucker at zip com au). + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ +/* + * openssh_bsd_setres_id.c - setresuid() and setresgid() wrappers + * + * This file is part of zsh, the Z shell. + * + * It is based on the file openbsd-compat/bsd-setres_id.c in OpenSSH 7.9p1, + * which is subject to the copyright notice above. The zsh modifications are + * licensed as follows: + * + * Copyright (c) 2019 Daniel Shahaf + * All rights reserved. + * + * Permission is hereby granted, without written agreement and without + * license or royalty fees, to use, copy, modify, and distribute this + * software and to distribute modified versions of this software for any + * purpose, provided that the above copyright notice and the following + * two paragraphs appear in all copies of this software. + * + * In no event shall Daniel Shahaf or the Zsh Development Group be liable + * to any party for direct, indirect, special, incidental, or consequential + * damages arising out of the use of this software and its documentation, + * even if Daniel Shahaf and the Zsh Development Group have been advised of + * the possibility of such damage. + * + * Daniel Shahaf and the Zsh Development Group specifically disclaim any + * warranties, including, but not limited to, the implied warranties of + * merchantability and fitness for a particular purpose. The software + * provided hereunder is on an "as is" basis, and Daniel Shahaf and the + * Zsh Development Group have no obligation to provide maintenance, + * support, updates, enhancements, or modifications. + * + */ + + +#include + +#include +#include +#include + +#include "zsh.mdh" + +#if defined(ZSH_IMPLEMENT_SETRESGID) || defined(BROKEN_SETRESGID) +int +setresgid(gid_t rgid, gid_t egid, gid_t sgid) +{ + int ret = 0, saved_errno; + + if (rgid != sgid) { + errno = ENOSYS; + return -1; + } +#if defined(ZSH_HAVE_NATIVE_SETREGID) && !defined(BROKEN_SETREGID) + if (setregid(rgid, egid) < 0) { + saved_errno = errno; + zwarnnam("setregid", "to gid %L: %e", (long)rgid, errno); + errno = saved_errno; + ret = -1; + } +#else + if (setegid(egid) < 0) { + saved_errno = errno; + zwarnnam("setegid", "to gid %L: %e", (long)(unsigned int)egid, errno); + errno = saved_errno; + ret = -1; + } + if (setgid(rgid) < 0) { + saved_errno = errno; + zwarnnam("setgid", "to gid %L: %e", (long)rgid, errno); + errno = saved_errno; + ret = -1; + } +#endif + return ret; +} +#endif + +#if defined(ZSH_IMPLEMENT_SETRESUID) || defined(BROKEN_SETRESUID) +int +setresuid(uid_t ruid, uid_t euid, uid_t suid) +{ + int ret = 0, saved_errno; + + if (ruid != suid) { + errno = ENOSYS; + return -1; + } +#if defined(ZSH_HAVE_NATIVE_SETREUID) && !defined(BROKEN_SETREUID) + if (setreuid(ruid, euid) < 0) { + saved_errno = errno; + zwarnnam("setreuid", "to uid %L: %e", (long)ruid, errno); + errno = saved_errno; + ret = -1; + } +#else + +# ifndef SETEUID_BREAKS_SETUID + if (seteuid(euid) < 0) { + saved_errno = errno; + zwarnnam("seteuid", "to uid %L: %e", (long)euid, errno); + errno = saved_errno; + ret = -1; + } +# endif + if (setuid(ruid) < 0) { + saved_errno = errno; + zwarnnam("setuid", "to uid %L: %e", (long)ruid, errno); + errno = saved_errno; + ret = -1; + } +#endif + return ret; +} +#endif diff --git a/Src/options.c b/Src/options.c index 328cf318b..425e27dc2 100644 --- a/Src/options.c +++ b/Src/options.c @@ -607,25 +607,21 @@ bin_setopt(char *nam, char **args, UNUSED(Options ops), int isun) } if(!(optno = optlookup(*args))) { zwarnnam(nam, "no such option: %s", *args); - retval = 1; - } else { - retval = !!dosetopt(optno, action, 0, opts); - if (retval) { - zwarnnam(nam, "can't change option: %s", *args); - } + retval |= 1; + } else if (dosetopt(optno, action, 0, opts)) { + zwarnnam(nam, "can't change option: %s", *args); + retval |= 1; } break; } else if(**args == 'm') { match = 1; } else { - if (!(optno = optlookupc(**args))) { + if (!(optno = optlookupc(**args))) { zwarnnam(nam, "bad option: -%c", **args); - retval = 1; - } else { - retval = !!dosetopt(optno, action, 0, opts); - if (retval) { - zwarnnam(nam, "can't change option: -%c", **args); - } + retval |= 1; + } else if (dosetopt(optno, action, 0, opts)) { + zwarnnam(nam, "can't change option: -%c", **args); + retval |= 1; } } } @@ -638,12 +634,10 @@ bin_setopt(char *nam, char **args, UNUSED(Options ops), int isun) while (*args) { if(!(optno = optlookup(*args++))) { zwarnnam(nam, "no such option: %s", args[-1]); - retval = 1; - } else { - retval = !!dosetopt(optno, !isun, 0, opts); - if (retval) { - zwarnnam(nam, "can't change option: %s", args[-1]); - } + retval |= 1; + } else if (dosetopt(optno, !isun, 0, opts)) { + zwarnnam(nam, "can't change option: %s", args[-1]); + retval |= 1; } } } else { @@ -667,7 +661,7 @@ bin_setopt(char *nam, char **args, UNUSED(Options ops), int isun) tokenize(s); if (!(pprog = patcompile(s, PAT_HEAPDUP, NULL))) { zwarnnam(nam, "bad pattern: %s", *args); - retval = 1; + retval |= 1; break; } /* Loop over expansions. */ @@ -787,100 +781,92 @@ dosetopt(int optno, int value, int force, char *new_opts) } else if(optno == PRIVILEGED && !value) { /* unsetting PRIVILEGED causes the shell to make itself unprivileged */ - int skip_setuid = 0; - int skip_setgid = 0; - -#if defined(HAVE_GETEGID) && defined(HAVE_SETGID) && defined(HAVE_GETUID) - int orig_egid = getegid(); -#endif + /* If set, return -1 so lastval will be non-zero. */ + int failed = 0; -#if defined(HAVE_GETEUID) && defined(HAVE_GETUID) - if (geteuid() == getuid()) { - skip_setuid = 1; - } +#ifdef HAVE_SETUID + const int orig_euid = geteuid(); #endif + const int orig_egid = getegid(); -#if defined(HAVE_GETEGID) && defined(HAVE_GETGID) - if (getegid() == getgid()) { - skip_setgid = 1; - } -#endif - - if (!skip_setgid) { - int setgid_err; -#ifdef HAVE_SETRESGID - setgid_err = setresgid(getgid(), getgid(), getgid()); -#elif defined(HAVE_SETREGID) -#if defined(HAVE_GETEGID) && defined(HAVE_SETGID) && defined(HAVE_GETUID) - setgid_err = setregid(getgid(), getgid()); -#else - zwarnnam("unsetopt", - "PRIVILEGED: can't drop privileges; setregid available, but cannot check if saved gid changed"); + /* + * Set the GID first as if we set the UID to non-privileged it + * might be impossible to restore the GID. + */ + { +#ifndef HAVE_SETRESGID + zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; setresgid() and friends not available"); return -1; -#endif #else - zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; setresgid and setregid not available"); - return -1; -#endif + int setgid_err; + setgid_err = setresgid(getgid(), getgid(), getgid()); if (setgid_err) { zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; failed to change group ID: %e", errno); return -1; } +#endif } - if (!skip_setuid) { -#if defined(HAVE_GETEUID) && defined(HAVE_SETUID) - int orig_euid = geteuid(); -#endif + /* Set the UID second. */ + { +#ifndef HAVE_SETRESUID + zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; setresuid() and friends not available"); + return -1; +#else int setuid_err; -#if defined(HAVE_GETEUID) && defined(HAVE_INITGROUPS) && defined(HAVE_GETPWUID) + +# ifdef HAVE_INITGROUPS + /* Set the supplementary groups list. */ if (geteuid() == 0) { struct passwd *pw = getpwuid(getuid()); if (pw == NULL) { - zwarnnam("unsetopt", "can't drop privileges; failed to get user information for uid %d: %e", - getuid(), errno); - return -1; - } - if (initgroups(pw->pw_name, pw->pw_gid)) { + zwarnnam("unsetopt", "can't drop privileges; failed to get user information for uid %L: %e", + (long)getuid(), errno); + failed = 1; + } else if (initgroups(pw->pw_name, pw->pw_gid)) { zwarnnam("unsetopt", "can't drop privileges; failed to set supplementary group list: %e", errno); return -1; } + } else if (getuid() != 0 && + (geteuid() != getuid() || orig_egid != getegid())) { + zwarnnam("unsetopt", "PRIVILEGED: supplementary group list not changed due to lack of permissions: EUID=%L", + (long)geteuid()); + failed = 1; } -#endif +# else + /* initgroups() isn't in POSIX. If it's not available on the system, + * we silently skip it. */ +# endif -#ifdef HAVE_SETRESUID setuid_err = setresuid(getuid(), getuid(), getuid()); -#elif defined(HAVE_SETREUID) -#if defined(HAVE_GETEUID) && defined(HAVE_SETUID) && defined(HAVE_GETUID) - setuid_err = setreuid(getuid(), getuid()); -#else - zwarnnam("unsetopt", - "PRIVILEGED: can't drop privileges; setreuid available, but cannot check if saved uid changed"); - return -1; -#endif -#else - zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; setresuid and setreuid not available"); - return -1; -#endif if (setuid_err) { zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; failed to change user ID: %e", errno); return -1; } -#if defined(HAVE_GETEUID) && defined(HAVE_SETUID) && defined(HAVE_GETUID) - if (getuid() != 0 && !setuid(orig_euid)) { - zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; was able to restore the euid"); - return -1; - } #endif } -#if defined(HAVE_GETEGID) && defined(HAVE_SETGID) && defined(HAVE_GETUID) - if (getuid() != 0 && !skip_setgid && !setgid(orig_egid)) { +#ifdef HAVE_SETGID + if (getuid() != 0 && orig_egid != getegid() && + (setgid(orig_egid) != -1 || setegid(orig_egid) != -1)) { zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; was able to restore the egid"); return -1; } #endif +#ifdef HAVE_SETUID + if (getuid() != 0 && orig_euid != geteuid() && + (setuid(orig_euid) != -1 || seteuid(orig_euid) != -1)) { + zwarnnam("unsetopt", "PRIVILEGED: can't drop privileges; was able to restore the euid"); + return -1; + } +#endif + + if (failed) { + /* A warning message has been printed. */ + return -1; + } + #ifdef JOB_CONTROL } else if (!force && optno == MONITOR && value) { if (new_opts[optno] == value) diff --git a/Src/zsh.mdd b/Src/zsh.mdd index 3e5788af5..9bcaccae5 100644 --- a/Src/zsh.mdd +++ b/Src/zsh.mdd @@ -13,7 +13,8 @@ objects="builtin.o compat.o cond.o context.o \ exec.o glob.o hashtable.o hashnameddir.o \ hist.o init.o input.o jobs.o lex.o linklist.o loop.o math.o \ mem.o module.o options.o params.o parse.o pattern.o prompt.o signals.o \ -signames.o sort.o string.o subst.o text.o utils.o watch.o" +signames.o sort.o string.o subst.o text.o utils.o watch.o \ +openssh_bsd_setres_id.o" headers="../config.h zsh_system.h zsh.h sigcount.h signals.h \ prototypes.h hashtable.h ztype.h" diff --git a/Src/zsh_system.h b/Src/zsh_system.h index 85e198f2e..161b073b4 100644 --- a/Src/zsh_system.h +++ b/Src/zsh_system.h @@ -468,30 +468,90 @@ struct timespec { # define setpgrp setpgid #endif -/* can we set the user/group id of a process */ +/* compatibility wrappers */ -#ifndef HAVE_SETUID +/* Our strategy is as follows: + * + * - Ensure that either setre[ug]id() or set{e,}[ug]id() is available. + * - If setres[ug]id() are missing, provide them in terms of either + * setre[ug]id() or set{e,}[ug]id(), whichever is available. + * - Provide replacement setre[ug]id() or set{e,}[ug]id() if they are not + * available natively. + * + * There isn't a circular dependency because, right off the bat, we check that + * there's an end condition, and #error out otherwise. + */ +#if !defined(HAVE_SETREUID) && !(defined(HAVE_SETEUID) && defined(HAVE_SETUID)) + /* + * If you run into this error, you have two options: + * - Teach zsh how to do the equivalent of setreuid() on your system + * - Remove support for PRIVILEGED option, and then remove the #error. + */ +# error "Don't know how to change UID" +#endif +#if !defined(HAVE_SETREGID) && !(defined(HAVE_SETEGID) && defined(HAVE_SETGID)) + /* See above comment. */ +# error "Don't know how to change GID" +#endif + +/* Provide setresuid(). */ +#ifndef HAVE_SETRESUID +int setresuid(uid_t, uid_t, uid_t); +# define HAVE_SETRESUID +# define ZSH_IMPLEMENT_SETRESUID # ifdef HAVE_SETREUID -# define setuid(X) setreuid(X,X) -# define setgid(X) setregid(X,X) -# define HAVE_SETUID +# define ZSH_HAVE_NATIVE_SETREUID # endif #endif -/* can we set the effective user/group id of a process */ +/* Provide setresgid(). */ +#ifndef HAVE_SETRESGID +int setresgid(gid_t, gid_t, gid_t); +# define HAVE_SETRESGID +# define ZSH_IMPLEMENT_SETRESGID +# ifdef HAVE_SETREGID +# define ZSH_HAVE_NATIVE_SETREGID +# endif +#endif +/* Provide setreuid(). */ +#ifndef HAVE_SETREUID +# define setreuid(X, Y) setresuid((X), (Y), -1) +# define HAVE_SETREUID +#endif + +/* Provide setregid(). */ +#ifndef HAVE_SETREGID +# define setregid(X, Y) setresgid((X), (Y), -1) +# define HAVE_SETREGID +#endif + +/* Provide setuid(). */ +/* ### TODO: Either remove this (this function has been standard since 1985), + * ### or rewrite this without multiply-evaluating the argument */ +#ifndef HAVE_SETUID +# define setuid(X) setreuid((X), (X)) +# define HAVE_SETUID +#endif + +/* Provide setgid(). */ +#ifndef HAVE_SETGID +/* ### TODO: Either remove this (this function has been standard since 1985), + * ### or rewrite this without multiply-evaluating the argument */ +# define setgid(X) setregid((X), (X)) +# define HAVE_SETGID +#endif + +/* Provide seteuid(). */ #ifndef HAVE_SETEUID -# ifdef HAVE_SETREUID -# define seteuid(X) setreuid(-1,X) -# define setegid(X) setregid(-1,X) -# define HAVE_SETEUID -# else -# ifdef HAVE_SETRESUID -# define seteuid(X) setresuid(-1,X,-1) -# define setegid(X) setresgid(-1,X,-1) -# define HAVE_SETEUID -# endif -# endif +# define seteuid(X) setreuid(-1, (X)) +# define HAVE_SETEUID +#endif + +/* Provide setegid(). */ +#ifndef HAVE_SETEGID +# define setegid(X) setregid(-1, (X)) +# define HAVE_SETEGID #endif #ifdef HAVE_SYS_RESOURCE_H diff --git a/Test/E01options.ztst b/Test/E01options.ztst index c4b101bdb..680f49082 100644 --- a/Test/E01options.ztst +++ b/Test/E01options.ztst @@ -1391,3 +1391,18 @@ F:Regression test for workers/41811 ?(anon):4: `break' active at end of function scope ?(anon):4: `break' active at end of function scope ?(anon):4: `break' active at end of function scope + +# There are further tests for PRIVILEGED in P01privileged.ztst. + if [[ -o privileged ]]; then + unsetopt privileged + fi + unsetopt privileged +0:PRIVILEGED sanity check: unsetting is idempotent +F:If this test fails at the first unsetopt, refer to P01privileged.ztst. + + if [[ -o privileged ]]; then + (( UID != EUID )) + else + (( UID == EUID )) + fi +0:PRIVILEGED sanity check: default value is correct diff --git a/configure.ac b/configure.ac index 2474c270e..f2d65ecfc 100644 --- a/configure.ac +++ b/configure.ac @@ -1310,9 +1310,8 @@ AC_CHECK_FUNCS(strftime strptime mktime timelocal \ inet_aton inet_pton inet_ntop \ getlogin getpwent getpwnam getpwuid getgrgid getgrnam \ initgroups nis_list \ - getuid setuid seteuid setreuid setresuid setsid \ - getgid setgid setegid setregid setresgid \ - geteuid getegid \ + setuid seteuid setreuid setresuid setsid \ + setgid setegid setregid setresgid \ memcpy memmove strstr strerror strtoul \ getrlimit getrusage \ setlocale \ -- cgit 1.4.1