-/* su for GNU. Run a shell with substitute user and group IDs.
- Copyright (C) 1992-2006 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 2, or (at your option)
- any later version.
+#include "su-common.h"
- 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, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
-
-/* 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>
-
-/* Hide any system prototype for getusershell.
- This is necessary because some Cray systems have a conflicting
- prototype (returning `int') in <unistd.h>. */
-#define getusershell _getusershell_sys_proto_
-
-#include "system.h"
-#include "dirname.h"
-#include "getpass.h"
-
-#undef getusershell
-
-#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 "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 *getusershell ();
-void endusershell ();
-void setusershell ();
-
-extern char **environ;
-
-static void run_shell (char const *, char const *, char **, size_t)
- ATTRIBUTE_NORETURN;
-
-/* The name this program was run with. */
-char *program_name;
-
-/* 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[] =
+int main(int argc, char **argv)
{
- {"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 ();
+ return su_main(argc, argv, SU_MODE);
}
-#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. */
- struct passwd *pwd = getpwuid (getuid ());
- 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_FAIL, errno, _("cannot set groups"));
- endgrent ();
-#endif
- if (setgid (pw->pw_gid))
- error (EXIT_FAIL, errno, _("cannot set group id"));
- if (setuid (pw->pw_uid))
- error (EXIT_FAIL, 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)
- fprintf (stderr, _("Try `%s --help' for more information.\n"),
- program_name);
- 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);
- printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
- }
- 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);
- program_name = argv[0];
- setlocale (LC_ALL, "");
- bindtextdomain (PACKAGE, LOCALEDIR);
- textdomain (PACKAGE);
-
- initialize_exit_failure (EXIT_FAIL);
- 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_FAIL);
- }
- }
-
- 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_FAIL, 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. 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_FAIL, 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);
-
- run_shell (shell, command, argv + optind, MAX (0, argc - optind));
-}
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