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File su.patch of Package coreutils (Revision 1adf39de2ce4b519a912f90f9fac27df)

Currently displaying revision 1adf39de2ce4b519a912f90f9fac27df , Show latest

--- a/configure.ac
+++ b/configure.ac
@@ -380,6 +380,7 @@ AC_CHECK_DECLS([strsignal, sys_siglist, _sys_siglist, __sys_siglist], , ,
   [AC_INCLUDES_DEFAULT
 #include <signal.h>])
 
+cu_LIB_CHECK
 cu_GMP
 
 # Build df only if there's a point to it.
@@ -420,7 +421,7 @@ t=`sed -n '/^'$v' =/,/[[^\]]$/p' $mk \
 no_install_progs_default=`echo "$t"|sed 's/ $//'`
 
 # Unfortunately, due to the way autoconf's AS_HELP_STRING works, the list
-# of default-not-installed programs, "arch hostname", must appear in two
+# of default-not-installed programs, "arch hostname su", must appear in two
 # places: in this file below, and in $mk.  Using "$no_install_progs_default"
 # below cannot work.  And we can't substitute the names into $mk because
 # automake needs the literals, too.
@@ -447,7 +448,7 @@ esac
 # Note how the second argument below is a literal, with "," separators.
 # That is required due to the way the macro works, and since the
 # corresponding ./configure option argument is comma-separated on input.
-gl_INCLUDE_EXCLUDE_PROG([optional_bin_progs], [arch,hostname])
+gl_INCLUDE_EXCLUDE_PROG([optional_bin_progs], [arch,hostname,su])
 
 # Now that we know which programs will actually be built up, figure out
 # which optional helper progs should be compiled.
@@ -456,6 +457,14 @@ case " $optional_bin_progs " in
   *' stdbuf '*) gl_ADD_PROG([optional_pkglib_progs], [libstdbuf.so]) ;;
 esac
 
+# Set INSTALL_SU if su installation has been requested via
+# --enable-install-program=su.
+AC_SUBST([INSTALL_SU])
+case " $optional_bin_progs " in
+  *' su '*) INSTALL_SU=yes ;;
+  *)        INSTALL_SU=no ;;
+esac
+
 MAN=`echo "$optional_bin_progs "|sed 's/ /.1 /g;s/ $//'|tr -d '\\015\\012'`
 
 # Change "ginstall.1" to "install.1" in $MAN.
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -109,6 +109,7 @@
 * stat: (coreutils)stat invocation.             Report file(system) status.
 * stdbuf: (coreutils)stdbuf invocation.         Modify stdio buffering.
 * stty: (coreutils)stty invocation.             Print/change terminal settings.
+* su: (coreutils)su invocation.                 Modify user and group ID.
 * sum: (coreutils)sum invocation.               Print traditional checksum.
 * sync: (coreutils)sync invocation.             Synchronize memory and disk.
 * tac: (coreutils)tac invocation.               Reverse files.
@@ -199,7 +200,7 @@ Top
 * User information::             id logname whoami groups users who
 * System context::               date arch nproc uname hostname hostid uptime
 * SELinux context::              chcon runcon
-* Modified command invocation::  chroot env nice nohup stdbuf timeout
+* Modified command invocation::  chroot env nice nohup stdbuf su timeout
 * Process control::              kill
 * Delaying::                     sleep
 * Numeric operations::           factor seq
@@ -442,6 +443,7 @@ Top
 * nice invocation::              Run a command with modified niceness
 * nohup invocation::             Run a command immune to hangups
 * stdbuf invocation::            Run a command with modified I/O buffering
+* su invocation::                Run a command with substitute user and group ID
 * timeout invocation::           Run a command with a time limit
 
 Process control
@@ -764,7 +766,7 @@ Exit status
 Here are some of the exceptions:
 @command{chroot}, @command{env}, @command{expr}, @command{nice},
 @command{nohup}, @command{printenv}, @command{sort}, @command{stdbuf},
-@command{test}, @command{timeout}, @command{tty}.
+@command{su}, @command{test}, @command{timeout}, @command{tty}.
 
 
 @node Backup options
@@ -15264,6 +15266,7 @@ Modified command invocation
 * nice invocation::             Modify niceness.
 * nohup invocation::            Immunize to hangups.
 * stdbuf invocation::           Modify buffering of standard streams.
+* su invocation::               Modify user and group ID.
 * timeout invocation::          Run with time limit.
 @end menu
 
@@ -15791,6 +15794,163 @@ stdbuf invocation
 @end display
 
 
+@node su invocation
+@section @command{su}: Run a command with substitute user and group ID
+
+@pindex su
+@cindex substitute user and group IDs
+@cindex user ID, switching
+@cindex super-user, becoming
+@cindex root, becoming
+
+@command{su} allows one user to temporarily become another user.  It runs a
+command (often an interactive shell) with the real and effective user
+ID, group ID, and supplemental groups of a given @var{user}.  Synopsis:
+
+@example
+su [@var{option}]@dots{} [@var{user} [@var{arg}]@dots{}]
+@end example
+
+@cindex passwd entry, and @command{su} shell
+@flindex /bin/sh
+@flindex /etc/passwd
+If no @var{user} is given, the default is @code{root}, the super-user.
+The shell to use is taken from @var{user}'s @code{passwd} entry, or
+@file{/bin/sh} if none is specified there.  If @var{user} has a
+password, @command{su} prompts for the password unless run by a user with
+effective user ID of zero (the super-user).
+
+@vindex HOME
+@vindex SHELL
+@vindex USER
+@vindex LOGNAME
+@cindex login shell
+By default, @command{su} does not change the current directory.
+It sets the environment variables @env{HOME} and @env{SHELL}
+from the password entry for @var{user}, and if @var{user} is not
+the super-user, sets @env{USER} and @env{LOGNAME} to @var{user}.
+By default, the shell is not a login shell.
+
+Any additional @var{arg}s are passed as additional arguments to the
+shell.
+
+@cindex @option{-su}
+GNU @command{su} does not treat @file{/bin/sh} or any other shells specially
+(e.g., by setting @code{argv[0]} to @option{-su}, passing @option{-c} only
+to certain shells, etc.).
+
+@findex syslog
+@command{su} can optionally be compiled to use @code{syslog} to report
+failed, and optionally successful, @command{su} attempts.  (If the system
+supports @code{syslog}.)  However, GNU @command{su} does not check if the
+user is a member of the @code{wheel} group; see below.
+
+The program accepts the following options.  Also see @ref{Common options}.
+
+@table @samp
+@item -c @var{command}
+@itemx --command=@var{command}
+@opindex -c
+@opindex --command
+Pass @var{command}, a single command line to run, to the shell with
+a @option{-c} option instead of starting an interactive shell.
+
+@item -f
+@itemx --fast
+@opindex -f
+@opindex --fast
+@flindex .cshrc
+@cindex file name pattern expansion, disabled
+@cindex globbing, disabled
+Pass the @option{-f} option to the shell.  This probably only makes sense
+if the shell run is @command{csh} or @command{tcsh}, for which the @option{-f}
+option prevents reading the startup file (@file{.cshrc}).  With
+Bourne-like shells, the @option{-f} option disables file name pattern
+expansion (globbing), which is not likely to be useful.
+
+@item -
+@itemx -l
+@itemx --login
+@opindex -
+@opindex -l
+@opindex --login
+@c other variables already indexed above
+@vindex TERM
+@vindex PATH
+@cindex login shell, creating
+Make the shell a login shell.  This means the following.  Unset all
+environment variables except @env{TERM}, @env{HOME}, and @env{SHELL}
+(which are set as described above), and @env{USER} and @env{LOGNAME}
+(which are set, even for the super-user, as described above), and set
+@env{PATH} to a compiled-in default value.  Change to @var{user}'s home
+directory.  Prepend @samp{-} to the shell's name, intended to make it
+read its login startup file(s).
+
+@item -m
+@itemx -p
+@itemx --preserve-environment
+@opindex -m
+@opindex -p
+@opindex --preserve-environment
+@cindex environment, preserving
+@flindex /etc/shells
+@cindex restricted shell
+Do not change the environment variables @env{HOME}, @env{USER},
+@env{LOGNAME}, or @env{SHELL}.  Run the shell given in the environment
+variable @env{SHELL} instead of the shell from @var{user}'s passwd
+entry, unless the user running @command{su} is not the super-user and
+@var{user}'s shell is restricted.  A @dfn{restricted shell} is one that
+is not listed in the file @file{/etc/shells}, or in a compiled-in list
+if that file does not exist.  Parts of what this option does can be
+overridden by @option{--login} and @option{--shell}.
+
+@item -s @var{shell}
+@itemx --shell=@var{shell}
+@opindex -s
+@opindex --shell
+Run @var{shell} instead of the shell from @var{user}'s passwd entry,
+unless the user running @command{su} is not the super-user and @var{user}'s
+shell is restricted (see @option{-m} just above).
+
+@end table
+
+@cindex exit status of @command{su}
+Exit status:
+
+@display
+125 if @command{su} itself fails
+126 if subshell is found but cannot be invoked
+127 if subshell cannot be found
+the exit status of the subshell otherwise
+@end display
+
+@cindex wheel group, not supported
+@cindex group wheel, not supported
+@cindex fascism
+@subsection Why GNU @command{su} does not support the @samp{wheel} group
+
+(This section is by Richard Stallman.)
+
+@cindex Twenex
+@cindex MIT AI lab
+Sometimes a few of the users try to hold total power over all the
+rest.  For example, in 1984, a few users at the MIT AI lab decided to
+seize power by changing the operator password on the Twenex system and
+keeping it secret from everyone else.  (I was able to thwart this coup
+and give power back to the users by patching the kernel, but I
+wouldn't know how to do that in Unix.)
+
+However, occasionally the rulers do tell someone.  Under the usual
+@command{su} mechanism, once someone learns the root password who
+sympathizes with the ordinary users, he or she can tell the rest.  The
+``wheel group'' feature would make this impossible, and thus cement the
+power of the rulers.
+
+I'm on the side of the masses, not that of the rulers.  If you are
+used to supporting the bosses and sysadmins in whatever they do, you
+might find this idea strange at first.
+
+
 @node timeout invocation
 @section @command{timeout}: Run a command with a time limit
 
--- /dev/null
+++ b/m4/lib-check.m4
@@ -0,0 +1,60 @@
+#serial 11
+
+dnl Misc lib-related macros for coreutils.
+
+# Copyright (C) 1993-2012 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program 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 General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Written by Jim Meyering.
+
+AC_DEFUN([cu_LIB_CHECK],
+[
+
+  # Check for libypsec.a on Dolphin M88K machines.
+  AC_CHECK_LIB([ypsec], [main])
+
+  # m88k running dgux 5.4 needs this
+  AC_CHECK_LIB([ldgc], [main])
+
+  # The -lsun library is required for YP support on Irix-4.0.5 systems.
+  # m88k/svr3 DolphinOS systems using YP need -lypsec for id.
+  AC_SEARCH_LIBS([yp_match], [sun ypsec])
+
+  # SysV needs -lsec, older versions of Linux need -lshadow for
+  # shadow passwords.  UnixWare 7 needs -lgen.
+  AC_SEARCH_LIBS([getspnam], [shadow sec gen])
+
+  AC_CHECK_HEADERS([shadow.h])
+
+  # Requirements for su.c.
+  shadow_includes="\
+$ac_includes_default
+#if HAVE_SHADOW_H
+# include <shadow.h>
+#endif
+"
+  AC_CHECK_MEMBERS([struct spwd.sp_pwdp],,,[$shadow_includes])
+  AC_CHECK_FUNCS([getspnam])
+
+  # SCO-ODT-3.0 is reported to need -lufc for crypt.
+  # NetBSD needs -lcrypt for crypt.
+  LIB_CRYPT=
+  cu_saved_libs="$LIBS"
+  AC_SEARCH_LIBS([crypt], [ufc crypt],
+                 [test "$ac_cv_search_crypt" = "none required" ||
+                  LIB_CRYPT="$ac_cv_search_crypt"])
+  LIBS="$cu_saved_libs"
+  AC_SUBST([LIB_CRYPT])
+])
--- a/man/Makefile.am
+++ b/man/Makefile.am
@@ -110,6 +110,7 @@ split.1:	$(common_dep)	$(srcdir)/split.x	../src/split.c
 stat.1:		$(common_dep)	$(srcdir)/stat.x	../src/stat.c
 stdbuf.1:	$(common_dep)	$(srcdir)/stdbuf.x	../src/stdbuf.c
 stty.1:		$(common_dep)	$(srcdir)/stty.x	../src/stty.c
+su.1:		$(common_dep)	$(srcdir)/su.x		../src/su.c
 sum.1:		$(common_dep)	$(srcdir)/sum.x		../src/sum.c
 sync.1:		$(common_dep)	$(srcdir)/sync.x	../src/sync.c
 tac.1:		$(common_dep)	$(srcdir)/tac.x		../src/tac.c
@@ -191,7 +192,7 @@ ASSORT = LC_ALL=C sort
 
 # Ensure that for each .x file in this directory, there is a
 # corresponding .1 file in the definition of $(dist_man1_MANS) above.
-# But since that expansion usually lacks programs like arch and hostname,
+# But since that expansion usually lacks programs like su and arch,
 # add them here manually.
 .PHONY: check-x-vs-1
 check-x-vs-1:
--- /dev/null
+++ b/man/su.x
@@ -0,0 +1,4 @@
+[NAME]
+su \- run a shell with substitute user and group IDs
+[DESCRIPTION]
+.\" Add any additional description here
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -118,6 +118,7 @@ src/split.c
 src/stat.c
 src/stdbuf.c
 src/stty.c
+src/su.c
 src/sum.c
 src/sync.c
 src/system.h
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -21,7 +21,7 @@
 # Hence, if you want to install programs from this list anyway, say A and B,
 # use --enable-install-program=A,B
 no_install__progs = \
-  arch hostname
+  arch hostname su
 
 build_if_possible__progs = \
   chroot	\
@@ -32,6 +32,7 @@ build_if_possible__progs = \
   pinky		\
   stdbuf	\
   stty		\
+  su		\
   uptime	\
   users		\
   who
@@ -163,7 +164,7 @@ noinst_HEADERS =	\
 EXTRA_DIST = dcgen dircolors.hin tac-pipe.c \
   wheel-gen.pl extract-magic c99-to-c89.diff
 BUILT_SOURCES =
-CLEANFILES = $(SCRIPTS)
+CLEANFILES = $(SCRIPTS) su
 
 # Also remove these sometimes-built programs.
 # For example, even when excluded, they're built via _sc_check-AUTHORS.
@@ -267,6 +268,7 @@ split_LDADD = $(LDADD)
 stat_LDADD = $(LDADD)
 stdbuf_LDADD = $(LDADD)
 stty_LDADD = $(LDADD)
+su_LDADD = $(LDADD)
 sum_LDADD = $(LDADD)
 sync_LDADD = $(LDADD)
 tac_LDADD = $(LDADD)
@@ -355,6 +357,9 @@ factor_LDADD += $(LIB_GMP)
 # for getloadavg
 uptime_LDADD += $(GETLOADAVG_LIBS)
 
+# for crypt
+su_LDADD += $(LIB_CRYPT)
+
 # for various ACL functions
 copy_LDADD += $(LIB_ACL)
 ls_LDADD += $(LIB_ACL)
@@ -397,6 +402,60 @@ RELEASE_YEAR = \
   `sed -n '/.*COPYRIGHT_YEAR = $[0-9][0-9][0-9][0-9]$ };/s//\1/p' \
     $(top_srcdir)/lib/version-etc.c`
 
+all-local: su$(EXEEXT)
+
+installed_su = $(DESTDIR)$(bindir)/`echo su|sed '$(transform)'`
+
+setuid_root_mode = a=rx,u+s
+
+install_su =						\
+  if test "$(INSTALL_SU)" = yes; then			\
+    p=su;						\
+    echo " $(INSTALL_PROGRAM) $$p $(installed_su)";	\
+    $(INSTALL_PROGRAM) $$p $(installed_su);		\
+    echo " chown root $(installed_su)";			\
+    chown root $(installed_su);				\
+    echo " chmod $(setuid_root_mode) $(installed_su)";	\
+    chmod $(setuid_root_mode) $(installed_su);		\
+  else							\
+    :;							\
+  fi
+
+install-root: su$(EXEEXT)
+	@$(install_su)
+
+install-exec-hook: su$(EXEEXT)
+	@if test "$(INSTALL_SU)" = yes; then			\
+	  TMPFILE=$(DESTDIR)$(bindir)/.su-$$$$;			\
+	  rm -f $$TMPFILE;					\
+	  echo > $$TMPFILE;					\
+## See if we can create a setuid root executable in $(bindir).
+## If not, then don't even try to install su.
+	  can_create_suid_root_executable=no;			\
+	  chown root $$TMPFILE > /dev/null 2>&1			\
+	    && chmod $(setuid_root_mode) $$TMPFILE > /dev/null 2>&1 \
+	    && can_create_suid_root_executable=yes;		\
+	  rm -f $$TMPFILE;					\
+	  if test $$can_create_suid_root_executable = yes; then \
+	    $(install_su);					\
+	  else							\
+	    echo "WARNING: insufficient access; not installing su"; \
+	    echo "NOTE: to install su, run 'make install-root' as root"; \
+	    rm -f $(installed_su);				\
+	  fi;							\
+	else :;							\
+	fi
+
+uninstall-local:
+# Remove su only if it's one we installed.
+	@if test "$(INSTALL_SU)" = yes; then			\
+	  if grep '$(PACKAGE_NAME)' $(installed_su) > /dev/null 2>&1; then \
+	    echo "  rm -f $(installed_su)"; \
+	    rm -f $(installed_su); \
+	  else :; \
+	  fi; \
+	fi
+
 copy_sources = copy.c cp-hash.c extent-scan.c extent-scan.h
 
 # Use 'ginstall' in the definition of PROGRAMS and in dependencies to avoid
--- /dev/null
+++ b/src/su.c
@@ -0,0 +1,520 @@
+/* su for GNU.  Run a shell with substitute user and group IDs.
+   Copyright (C) 1992-2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Run a shell with the real and effective UID and GID and groups
+   of USER, default 'root'.
+
+   The shell run is taken from USER's password entry, /bin/sh if
+   none is specified there.  If the account has a password, su
+   prompts for a password unless run by a user with real UID 0.
+
+   Does not change the current directory.
+   Sets 'HOME' and 'SHELL' from the password entry for USER, and if
+   USER is not root, sets 'USER' and 'LOGNAME' to USER.
+   The subshell is not a login shell.
+
+   If one or more ARGs are given, they are passed as additional
+   arguments to the subshell.
+
+   Does not handle /bin/sh or other shells specially
+   (setting argv[0] to "-su", passing -c only to certain shells, etc.).
+   I don't see the point in doing that, and it's ugly.
+
+   This program intentionally does not support a "wheel group" that
+   restricts who can su to UID 0 accounts.  RMS considers that to
+   be fascist.
+
+   Compile-time options:
+   -DSYSLOG_SUCCESS	Log successful su's (by default, to root) with syslog.
+   -DSYSLOG_FAILURE	Log failed su's (by default, to root) with syslog.
+
+   -DSYSLOG_NON_ROOT	Log all su's, not just those to root (UID 0).
+   Never logs attempted su's to nonexistent accounts.
+
+   Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
+
+#include <config.h>
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "system.h"
+#include "getpass.h"
+
+#if HAVE_SYSLOG_H && HAVE_SYSLOG
+# include <syslog.h>
+#else
+# undef SYSLOG_SUCCESS
+# undef SYSLOG_FAILURE
+# undef SYSLOG_NON_ROOT
+#endif
+
+#if HAVE_SYS_PARAM_H
+# include <sys/param.h>
+#endif
+
+#ifndef HAVE_ENDGRENT
+# define endgrent() ((void) 0)
+#endif
+
+#ifndef HAVE_ENDPWENT
+# define endpwent() ((void) 0)
+#endif
+
+#if HAVE_SHADOW_H
+# include <shadow.h>
+#endif
+
+#include "error.h"
+
+/* The official name of this program (e.g., no 'g' prefix).  */
+#define PROGRAM_NAME "su"
+
+#define AUTHORS proper_name ("David MacKenzie")
+
+#if HAVE_PATHS_H
+# include <paths.h>
+#endif
+
+/* The default PATH for simulated logins to non-superuser accounts.  */
+#ifdef _PATH_DEFPATH
+# define DEFAULT_LOGIN_PATH _PATH_DEFPATH
+#else
+# define DEFAULT_LOGIN_PATH ":/usr/ucb:/bin:/usr/bin"
+#endif
+
+/* The default PATH for simulated logins to superuser accounts.  */
+#ifdef _PATH_DEFPATH_ROOT
+# define DEFAULT_ROOT_LOGIN_PATH _PATH_DEFPATH_ROOT
+#else
+# define DEFAULT_ROOT_LOGIN_PATH "/usr/ucb:/bin:/usr/bin:/etc"
+#endif
+
+/* The shell to run if none is given in the user's passwd entry.  */
+#define DEFAULT_SHELL "/bin/sh"
+
+/* The user to become if none is specified.  */
+#define DEFAULT_USER "root"
+
+char *crypt (char const *key, char const *salt);
+
+static void run_shell (char const *, char const *, char **, size_t)
+     ATTRIBUTE_NORETURN;
+
+/* If true, pass the '-f' option to the subshell.  */
+static bool fast_startup;
+
+/* If true, simulate a login instead of just starting a shell.  */
+static bool simulate_login;
+
+/* If true, change some environment vars to indicate the user su'd to.  */
+static bool change_environment;
+
+static struct option const longopts[] =
+{
+  {"command", required_argument, NULL, 'c'},
+  {"fast", no_argument, NULL, 'f'},
+  {"login", no_argument, NULL, 'l'},
+  {"preserve-environment", no_argument, NULL, 'p'},
+  {"shell", required_argument, NULL, 's'},
+  {GETOPT_HELP_OPTION_DECL},
+  {GETOPT_VERSION_OPTION_DECL},
+  {NULL, 0, NULL, 0}
+};
+
+/* Add NAME=VAL to the environment, checking for out of memory errors.  */
+
+static void
+xsetenv (char const *name, char const *val)
+{
+  size_t namelen = strlen (name);
+  size_t vallen = strlen (val);
+  char *string = xmalloc (namelen + 1 + vallen + 1);
+  strcpy (string, name);
+  string[namelen] = '=';
+  strcpy (string + namelen + 1, val);
+  if (putenv (string) != 0)
+    xalloc_die ();
+}
+
+#if defined SYSLOG_SUCCESS || defined SYSLOG_FAILURE
+/* Log the fact that someone has run su to the user given by PW;
+   if SUCCESSFUL is true, they gave the correct password, etc.  */
+
+static void
+log_su (struct passwd const *pw, bool successful)
+{
+  const char *new_user, *old_user, *tty;
+
+# ifndef SYSLOG_NON_ROOT
+  if (pw->pw_uid)
+    return;
+# endif
+  new_user = pw->pw_name;
+  /* The utmp entry (via getlogin) is probably the best way to identify
+     the user, especially if someone su's from a su-shell.  */
+  old_user = getlogin ();
+  if (!old_user)
+    {
+      /* getlogin can fail -- usually due to lack of utmp entry.
+         Resort to getpwuid.  */
+      errno = 0;
+      uid_t ruid = getuid ();
+      uid_t NO_UID = -1;
+      struct passwd *pwd = (ruid == NO_UID && errno ? NULL : getpwuid (ruid));
+      old_user = (pwd ? pwd->pw_name : "");
+    }
+  tty = ttyname (STDERR_FILENO);
+  if (!tty)
+    tty = "none";
+  /* 4.2BSD openlog doesn't have the third parameter.  */
+  openlog (last_component (program_name), 0
+# ifdef LOG_AUTH
+           , LOG_AUTH
+# endif
+           );
+  syslog (LOG_NOTICE,
+# ifdef SYSLOG_NON_ROOT
+          "%s(to %s) %s on %s",
+# else
+          "%s%s on %s",
+# endif
+          successful ? "" : "FAILED SU ",
+# ifdef SYSLOG_NON_ROOT
+          new_user,
+# endif
+          old_user, tty);
+  closelog ();
+}
+#endif
+
+/* Ask the user for a password.
+   Return true if the user gives the correct password for entry PW,
+   false if not.  Return true without asking for a password if run by UID 0
+   or if PW has an empty password.  */
+
+static bool
+correct_password (const struct passwd *pw)
+{
+  char *unencrypted, *encrypted, *correct;
+#if HAVE_GETSPNAM && HAVE_STRUCT_SPWD_SP_PWDP
+  /* Shadow passwd stuff for SVR3 and maybe other systems.  */
+  struct spwd *sp = getspnam (pw->pw_name);
+
+  endspent ();
+  if (sp)
+    correct = sp->sp_pwdp;
+  else
+#endif
+    correct = pw->pw_passwd;
+
+  if (getuid () == 0 || !correct || correct[0] == '\0')
+    return true;
+
+  unencrypted = getpass (_("Password:"));
+  if (!unencrypted)
+    {
+      error (0, 0, _("getpass: cannot open /dev/tty"));
+      return false;
+    }
+  encrypted = crypt (unencrypted, correct);
+  memset (unencrypted, 0, strlen (unencrypted));
+  return STREQ (encrypted, correct);
+}
+
+/* Update 'environ' for the new shell based on PW, with SHELL being
+   the value for the SHELL environment variable.  */
+
+static void
+modify_environment (const struct passwd *pw, const char *shell)
+{
+  if (simulate_login)
+    {
+      /* Leave TERM unchanged.  Set HOME, SHELL, USER, LOGNAME, PATH.
+         Unset all other environment variables.  */
+      char const *term = getenv ("TERM");
+      if (term)
+        term = xstrdup (term);
+      environ = xmalloc ((6 + !!term) * sizeof (char *));
+      environ[0] = NULL;
+      if (term)
+        xsetenv ("TERM", term);
+      xsetenv ("HOME", pw->pw_dir);
+      xsetenv ("SHELL", shell);
+      xsetenv ("USER", pw->pw_name);
+      xsetenv ("LOGNAME", pw->pw_name);
+      xsetenv ("PATH", (pw->pw_uid
+                        ? DEFAULT_LOGIN_PATH
+                        : DEFAULT_ROOT_LOGIN_PATH));
+    }
+  else
+    {
+      /* Set HOME, SHELL, and if not becoming a super-user,
+         USER and LOGNAME.  */
+      if (change_environment)
+        {
+          xsetenv ("HOME", pw->pw_dir);
+          xsetenv ("SHELL", shell);
+          if (pw->pw_uid)
+            {
+              xsetenv ("USER", pw->pw_name);
+              xsetenv ("LOGNAME", pw->pw_name);
+            }
+        }
+    }
+}
+
+/* Become the user and group(s) specified by PW.  */
+
+static void
+change_identity (const struct passwd *pw)
+{
+#ifdef HAVE_INITGROUPS
+  errno = 0;
+  if (initgroups (pw->pw_name, pw->pw_gid) == -1)
+    error (EXIT_CANCELED, errno, _("cannot set groups"));
+  endgrent ();
+#endif
+  if (setgid (pw->pw_gid))
+    error (EXIT_CANCELED, errno, _("cannot set group id"));
+  if (setuid (pw->pw_uid))
+    error (EXIT_CANCELED, errno, _("cannot set user id"));
+}
+
+/* Run SHELL, or DEFAULT_SHELL if SHELL is empty.
+   If COMMAND is nonzero, pass it to the shell with the -c option.
+   Pass ADDITIONAL_ARGS to the shell as more arguments; there
+   are N_ADDITIONAL_ARGS extra arguments.  */
+
+static void
+run_shell (char const *shell, char const *command, char **additional_args,
+           size_t n_additional_args)
+{
+  size_t n_args = 1 + fast_startup + 2 * !!command + n_additional_args + 1;
+  char const **args = xnmalloc (n_args, sizeof *args);
+  size_t argno = 1;
+
+  if (simulate_login)
+    {
+      char *arg0;
+      char *shell_basename;
+
+      shell_basename = last_component (shell);
+      arg0 = xmalloc (strlen (shell_basename) + 2);
+      arg0[0] = '-';
+      strcpy (arg0 + 1, shell_basename);
+      args[0] = arg0;
+    }
+  else
+    args[0] = last_component (shell);
+  if (fast_startup)
+    args[argno++] = "-f";
+  if (command)
+    {
+      args[argno++] = "-c";
+      args[argno++] = command;
+    }
+  memcpy (args + argno, additional_args, n_additional_args * sizeof *args);
+  args[argno + n_additional_args] = NULL;
+  execv (shell, (char **) args);
+
+  {
+    int exit_status = (errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
+    error (0, errno, "%s", shell);
+    exit (exit_status);
+  }
+}
+
+/* Return true if SHELL is a restricted shell (one not returned by
+   getusershell), else false, meaning it is a standard shell.  */
+
+static bool
+restricted_shell (const char *shell)
+{
+  char *line;
+
+  setusershell ();
+  while ((line = getusershell ()) != NULL)
+    {
+      if (*line != '#' && STREQ (line, shell))
+        {
+          endusershell ();
+          return false;
+        }
+    }
+  endusershell ();
+  return true;
+}
+
+void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    emit_try_help ();
+  else
+    {
+      printf (_("Usage: %s [OPTION]... [-] [USER [ARG]...]\n"), program_name);
+      fputs (_("\
+Change the effective user id and group id to that of USER.\n\
+\n\
+  -, -l, --login               make the shell a login shell\n\
+  -c, --command=COMMAND        pass a single COMMAND to the shell with -c\n\
+  -f, --fast                   pass -f to the shell (for csh or tcsh)\n\
+  -m, --preserve-environment   do not reset environment variables\n\
+  -p                           same as -m\n\
+  -s, --shell=SHELL            run SHELL if /etc/shells allows it\n\
+"), stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+      fputs (_("\
+\n\
+A mere - implies -l.   If USER not given, assume root.\n\
+"), stdout);
+      emit_ancillary_info ();
+    }
+  exit (status);
+}
+
+int
+main (int argc, char **argv)
+{
+  int optc;
+  const char *new_user = DEFAULT_USER;
+  char *command = NULL;
+  char *shell = NULL;
+  struct passwd *pw;
+  struct passwd pw_copy;
+
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+
+  initialize_exit_failure (EXIT_CANCELED);
+  atexit (close_stdout);
+
+  fast_startup = false;
+  simulate_login = false;
+  change_environment = true;
+
+  while ((optc = getopt_long (argc, argv, "c:flmps:", longopts, NULL)) != -1)
+    {
+      switch (optc)
+        {
+        case 'c':
+          command = optarg;
+          break;
+
+        case 'f':
+          fast_startup = true;
+          break;
+
+        case 'l':
+          simulate_login = true;
+          break;
+
+        case 'm':
+        case 'p':
+          change_environment = false;
+          break;
+
+        case 's':
+          shell = optarg;
+          break;
+
+        case_GETOPT_HELP_CHAR;
+
+        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
+
+        default:
+          usage (EXIT_CANCELED);
+        }
+    }
+
+  if (optind < argc && STREQ (argv[optind], "-"))
+    {
+      simulate_login = true;
+      ++optind;
+    }
+  if (optind < argc)
+    new_user = argv[optind++];
+
+  pw = getpwnam (new_user);
+  if (! (pw && pw->pw_name && pw->pw_name[0] && pw->pw_dir && pw->pw_dir[0]
+         && pw->pw_passwd))
+    error (EXIT_CANCELED, 0, _("user %s does not exist"), new_user);
+
+  /* Make a copy of the password information and point pw at the local
+     copy instead.  Otherwise, some systems (e.g. GNU/Linux) would clobber
+     the static data through the getlogin call from log_su.
+     Also, make sure pw->pw_shell is a nonempty string.
+     It may be NULL when NEW_USER is a username that is retrieved via NIS (YP),
+     but that doesn't have a default shell listed.  */
+  pw_copy = *pw;
+  pw = &pw_copy;
+  pw->pw_name = xstrdup (pw->pw_name);
+  pw->pw_passwd = xstrdup (pw->pw_passwd);
+  pw->pw_dir = xstrdup (pw->pw_dir);
+  pw->pw_shell = xstrdup (pw->pw_shell && pw->pw_shell[0]
+                          ? pw->pw_shell
+                          : DEFAULT_SHELL);
+  endpwent ();
+
+  if (!correct_password (pw))
+    {
+#ifdef SYSLOG_FAILURE
+      log_su (pw, false);
+#endif
+      error (EXIT_CANCELED, 0, _("incorrect password"));
+    }
+#ifdef SYSLOG_SUCCESS
+  else
+    {
+      log_su (pw, true);
+    }
+#endif
+
+  if (!shell && !change_environment)
+    shell = getenv ("SHELL");
+  if (shell && getuid () != 0 && restricted_shell (pw->pw_shell))
+    {
+      /* The user being su'd to has a nonstandard shell, and so is
+         probably a uucp account or has restricted access.  Don't
+         compromise the account by allowing access with a standard
+         shell.  */
+      error (0, 0, _("using restricted shell %s"), pw->pw_shell);
+      shell = NULL;
+    }
+  shell = xstrdup (shell ? shell : pw->pw_shell);
+  modify_environment (pw, shell);
+
+  change_identity (pw);
+  if (simulate_login && chdir (pw->pw_dir) != 0)
+    error (0, errno, _("warning: cannot change directory to %s"), pw->pw_dir);
+
+  /* error() flushes stderr, but does not check for write failure.
+     Normally, we would catch this via our atexit() hook of
+     close_stdout, but execv() gets in the way.  If stderr
+     encountered a write failure, there is no need to try calling
+     error() again.  */
+  if (ferror (stderr))
+    exit (EXIT_CANCELED);
+
+  run_shell (shell, command, argv + optind, MAX (0, argc - optind));
+}
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -280,6 +280,7 @@ TESTS =						\
   misc/stty-invalid				\
   misc/stty-pairs				\
   misc/stty-row-col				\
+  misc/su-fail					\
   misc/sum					\
   misc/sum-sysv					\
   misc/tac					\
--- a/tests/misc/help-version
+++ b/tests/misc/help-version
@@ -208,6 +208,7 @@ nohup_setup () { args=--version; }
 printf_setup () { args=foo; }
 seq_setup () { args=10; }
 sleep_setup () { args=0; }
+su_setup () { args=--version; }
 stdbuf_setup () { args="-oL true"; }
 timeout_setup () { args=--version; }
 
--- a/tests/misc/invalid-opt
+++ b/tests/misc/invalid-opt
@@ -36,6 +36,7 @@ my %exit_status =
     nohup => 125,
     sort => 2,
     stdbuf => 125,
+    su => 125,
     test => 0,
     timeout => 125,
     true => 0,
--- /dev/null
+++ b/tests/misc/su-fail
@@ -0,0 +1,30 @@
+#!/bin/sh
+# Test su failure cases
+
+# Copyright (C) 2009-2012 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program 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 General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+print_ver_ su
+
+require_built_ su
+
+# Very little that we can test without a root password
+su --- / true # unknown option
+test $? = 125 || fail=1
+su no_such_user
+test $? = 125 || fail=1
+
+Exit $fail

Places

File su.patch of Package coreutils (Revision 1adf39de2ce4b519a912f90f9fac27df)

Places