Adding upstream version 1:4.13+dfsg1.upstream/1%4.13+dfsg1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 541 insertions, 0 deletions

diff --git a/src/chsh.c b/src/chsh.c
new file mode 100644
index 0000000..21d1c3e
--- /dev/null
+++ b/src/chsh.c
@@ -0,0 +1,541 @@
+/*
+ * SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
+ * SPDX-FileCopyrightText: 1996 - 2000, Marek Michałkiewicz
+ * SPDX-FileCopyrightText: 2001 - 2006, Tomasz Kłoczko
+ * SPDX-FileCopyrightText: 2007 - 2011, Nicolas François
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <fcntl.h>
+#include <getopt.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include "defines.h"
+#include "getdef.h"
+#include "nscd.h"
+#include "sssd.h"
+#include "prototypes.h"
+#include "pwauth.h"
+#include "pwio.h"
+#ifdef USE_PAM
+#include "pam_defs.h"
+#endif
+/*@-exitarg@*/
+#include "exitcodes.h"
+#include "shadowlog.h"
+
+#ifndef SHELLS_FILE
+#define SHELLS_FILE "/etc/shells"
+#endif
+/*
+ * Global variables
+ */
+const char *Prog;		/* Program name */
+static bool amroot;		/* Real UID is root */
+static char loginsh[BUFSIZ];	/* Name of new login shell */
+/* command line options */
+static bool sflg = false;	/* -s - set shell from command line  */
+static bool pw_locked = false;
+
+/* external identifiers */
+
+/* local function prototypes */
+static /*@noreturn@*/void fail_exit (int code);
+static /*@noreturn@*/void usage (int status);
+static void new_fields (void);
+static bool shell_is_listed (const char *);
+static bool is_restricted_shell (const char *);
+static void process_flags (int argc, char **argv);
+static void check_perms (const struct passwd *pw);
+static void update_shell (const char *user, char *loginsh);
+
+/*
+ * fail_exit - do some cleanup and exit with the given error code
+ */
+static /*@noreturn@*/void fail_exit (int code)
+{
+	if (pw_locked) {
+		if (pw_unlock () == 0) {
+			fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, pw_dbname ());
+			SYSLOG ((LOG_ERR, "failed to unlock %s", pw_dbname ()));
+			/* continue */
+		}
+	}
+
+	closelog ();
+
+	exit (code);
+}
+
+/*
+ * usage - print command line syntax and exit
+ */
+static /*@noreturn@*/void usage (int status)
+{
+	FILE *usageout = (E_SUCCESS != status) ? stderr : stdout;
+	(void) fprintf (usageout,
+	                _("Usage: %s [options] [LOGIN]\n"
+	                  "\n"
+	                  "Options:\n"),
+	                Prog);
+	(void) fputs (_("  -h, --help                    display this help message and exit\n"), usageout);
+	(void) fputs (_("  -R, --root CHROOT_DIR         directory to chroot into\n"), usageout);
+	(void) fputs (_("  -s, --shell SHELL             new login shell for the user account\n"), usageout);
+	(void) fputs ("\n", usageout);
+	exit (status);
+}
+
+/*
+ * new_fields - change the user's login shell information interactively
+ *
+ * prompt the user for the login shell and change it according to the
+ * response, or leave it alone if nothing was entered.
+ */
+static void new_fields (void)
+{
+	puts (_("Enter the new value, or press ENTER for the default"));
+	change_field (loginsh, sizeof loginsh, _("Login Shell"));
+}
+
+/*
+ * is_restricted_shell - return true if the shell is restricted
+ *
+ */
+static bool is_restricted_shell (const char *sh)
+{
+	/*
+	 * Shells not listed in /etc/shells are considered to be restricted.
+	 * Changed this to avoid confusion with "rc" (the plan9 shell - not
+	 * restricted despite the name starting with 'r').  --marekm
+	 */
+	return !shell_is_listed (sh);
+}
+
+/*
+ * shell_is_listed - see if the user's login shell is listed in /etc/shells
+ *
+ * The /etc/shells file is read for valid names of login shells.  If the
+ * /etc/shells file does not exist the user cannot set any shell unless
+ * they are root.
+ *
+ * If getusershell() is available (Linux, *BSD, possibly others), use it
+ * instead of re-implementing it.
+ */
+static bool shell_is_listed (const char *sh)
+{
+	char *cp;
+	bool found = false;
+
+#ifndef HAVE_GETUSERSHELL
+	char buf[BUFSIZ];
+	FILE *fp;
+#endif
+
+#ifdef HAVE_GETUSERSHELL
+	setusershell ();
+	while ((cp = getusershell ())) {
+		if (strcmp (cp, sh) == 0) {
+			found = true;
+			break;
+		}
+	}
+	endusershell ();
+#else
+	fp = fopen (SHELLS_FILE, "r");
+	if (NULL == fp) {
+		return false;
+	}
+
+	while (fgets (buf, sizeof (buf), fp) == buf) {
+		cp = strrchr (buf, '\n');
+		if (NULL != cp) {
+			*cp = '\0';
+		}
+
+		if (buf[0] == '#') {
+			continue;
+		}
+
+		if (strcmp (buf, sh) == 0) {
+			found = true;
+			break;
+		}
+	}
+	fclose (fp);
+#endif
+	return found;
+}
+
+/*
+ * process_flags - parse the command line options
+ *
+ *	It will not return if an error is encountered.
+ */
+static void process_flags (int argc, char **argv)
+{
+	int c;
+	static struct option long_options[] = {
+		{"help",  no_argument,       NULL, 'h'},
+		{"root",  required_argument, NULL, 'R'},
+		{"shell", required_argument, NULL, 's'},
+		{NULL, 0, NULL, '\0'}
+	};
+
+	while ((c = getopt_long (argc, argv, "hR:s:",
+	                         long_options, NULL)) != -1) {
+		switch (c) {
+		case 'h':
+			usage (E_SUCCESS);
+			/*@notreached@*/break;
+		case 'R': /* no-op, handled in process_root_flag () */
+			break;
+		case 's':
+			sflg = true;
+			STRFCPY (loginsh, optarg);
+			break;
+		default:
+			usage (E_USAGE);
+		}
+	}
+
+	/*
+	 * There should be only one remaining argument at most and it should
+	 * be the user's name.
+	 */
+	if (argc > (optind + 1)) {
+		usage (E_USAGE);
+	}
+}
+
+/*
+ * check_perms - check if the caller is allowed to add a group
+ *
+ *	Non-root users are only allowed to change their shell, if their current
+ *	shell is not a restricted shell.
+ *
+ *	Non-root users must be authenticated.
+ *
+ *	It will not return if the user is not allowed.
+ */
+static void check_perms (const struct passwd *pw)
+{
+#ifdef USE_PAM
+	pam_handle_t *pamh = NULL;
+	int retval;
+	struct passwd *pampw;
+#endif
+
+	/*
+	 * Non-privileged users are only allowed to change the shell if the
+	 * UID of the user matches the current real UID.
+	 */
+	if (!amroot && pw->pw_uid != getuid ()) {
+		SYSLOG ((LOG_WARN, "can't change shell for '%s'", pw->pw_name));
+		fprintf (stderr,
+		         _("You may not change the shell for '%s'.\n"),
+		         pw->pw_name);
+		fail_exit (1);
+	}
+
+	/*
+	 * Non-privileged users are only allowed to change the shell if it
+	 * is not a restricted one.
+	 */
+	if (!amroot && is_restricted_shell (pw->pw_shell)) {
+		SYSLOG ((LOG_WARN, "can't change shell for '%s'", pw->pw_name));
+		fprintf (stderr,
+		         _("You may not change the shell for '%s'.\n"),
+		         pw->pw_name);
+		fail_exit (1);
+	}
+#ifdef WITH_SELINUX
+	/*
+	 * If the UID of the user does not match the current real UID,
+	 * check if the change is allowed by SELinux policy.
+	 */
+	if ((pw->pw_uid != getuid ())
+	    && (check_selinux_permit("chsh") != 0)) {
+		SYSLOG ((LOG_WARN, "can't change shell for '%s'", pw->pw_name));
+		fprintf (stderr,
+		         _("You may not change the shell for '%s'.\n"),
+		         pw->pw_name);
+		fail_exit (1);
+	}
+#endif
+
+#ifndef USE_PAM
+	/*
+	 * Non-privileged users are optionally authenticated (must enter
+	 * the password of the user whose information is being changed)
+	 * before any changes can be made. Idea from util-linux
+	 * chfn/chsh.  --marekm
+	 */
+	if (!amroot && getdef_bool ("CHSH_AUTH")) {
+		passwd_check (pw->pw_name, pw->pw_passwd, "chsh");
+        }
+
+#else				/* !USE_PAM */
+	pampw = getpwuid (getuid ()); /* local, no need for xgetpwuid */
+	if (NULL == pampw) {
+		fprintf (stderr,
+		         _("%s: Cannot determine your user name.\n"),
+		         Prog);
+		exit (E_NOPERM);
+	}
+
+	retval = pam_start ("chsh", pampw->pw_name, &conv, &pamh);
+
+	if (PAM_SUCCESS == retval) {
+		retval = pam_authenticate (pamh, 0);
+	}
+
+	if (PAM_SUCCESS == retval) {
+		retval = pam_acct_mgmt (pamh, 0);
+	}
+
+	if (PAM_SUCCESS != retval) {
+		fprintf (stderr, _("%s: PAM: %s\n"),
+		         Prog, pam_strerror (pamh, retval));
+		SYSLOG((LOG_ERR, "%s", pam_strerror (pamh, retval)));
+		if (NULL != pamh) {
+			(void) pam_end (pamh, retval);
+		}
+		exit (E_NOPERM);
+	}
+	(void) pam_end (pamh, retval);
+#endif				/* USE_PAM */
+}
+
+/*
+ * update_shell - update the user's shell in the passwd database
+ *
+ *	Commit the user's entry after changing her shell field.
+ *
+ *	It will not return in case of error.
+ */
+static void update_shell (const char *user, char *newshell)
+{
+	const struct passwd *pw;	/* Password entry from /etc/passwd   */
+	struct passwd pwent;		/* New password entry                */
+
+	/*
+	 * Before going any further, raise the ulimit to prevent
+	 * colliding into a lowered ulimit, and set the real UID
+	 * to root to protect against unexpected signals. Any
+	 * keyboard signals are set to be ignored.
+	 */
+	if (setuid (0) != 0) {
+		SYSLOG ((LOG_ERR, "can't setuid(0)"));
+		fputs (_("Cannot change ID to root.\n"), stderr);
+		fail_exit (1);
+	}
+	pwd_init ();
+
+	/*
+	 * The passwd entry is now ready to be committed back to
+	 * the password file. Get a lock on the file and open it.
+	 */
+	if (pw_lock () == 0) {
+		fprintf (stderr, _("%s: cannot lock %s; try again later.\n"),
+		         Prog, pw_dbname ());
+		fail_exit (1);
+	}
+	pw_locked = true;
+	if (pw_open (O_CREAT | O_RDWR) == 0) {
+		fprintf (stderr, _("%s: cannot open %s\n"), Prog, pw_dbname ());
+		SYSLOG ((LOG_WARN, "cannot open %s", pw_dbname ()));
+		fail_exit (1);
+	}
+
+	/*
+	 * Get the entry to update using pw_locate() - we want the real
+	 * one from /etc/passwd, not the one from getpwnam() which could
+	 * contain the shadow password if (despite the warnings) someone
+	 * enables AUTOSHADOW (or SHADOW_COMPAT in libc).  --marekm
+	 */
+	pw = pw_locate (user);
+	if (NULL == pw) {
+		fprintf (stderr,
+		         _("%s: user '%s' does not exist in %s\n"),
+		         Prog, user, pw_dbname ());
+		fail_exit (1);
+	}
+
+	/*
+	 * Make a copy of the entry, then change the shell field. The other
+	 * fields remain unchanged.
+	 */
+	pwent = *pw;
+	pwent.pw_shell = newshell;
+
+	/*
+	 * Update the passwd file entry. If there is a DBM file, update
+	 * that entry as well.
+	 */
+	if (pw_update (&pwent) == 0) {
+		fprintf (stderr,
+		         _("%s: failed to prepare the new %s entry '%s'\n"),
+		         Prog, pw_dbname (), pwent.pw_name);
+		fail_exit (1);
+	}
+
+	/*
+	 * Changes have all been made, so commit them and unlock the file.
+	 */
+	if (pw_close () == 0) {
+		fprintf (stderr, _("%s: failure while writing changes to %s\n"), Prog, pw_dbname ());
+		SYSLOG ((LOG_ERR, "failure while writing changes to %s", pw_dbname ()));
+		fail_exit (1);
+	}
+	if (pw_unlock () == 0) {
+		fprintf (stderr, _("%s: failed to unlock %s\n"), Prog, pw_dbname ());
+		SYSLOG ((LOG_ERR, "failed to unlock %s", pw_dbname ()));
+		/* continue */
+	}
+	pw_locked= false;
+}
+
+/*
+ * chsh - this command controls changes to the user's shell
+ *
+ *	The only supported option is -s which permits the the login shell to
+ *	be set from the command line.
+ */
+int main (int argc, char **argv)
+{
+	char *user;		/* User name                         */
+	const struct passwd *pw;	/* Password entry from /etc/passwd   */
+
+	sanitize_env ();
+
+	/*
+	 * Get the program name. The program name is used as a prefix to
+	 * most error messages.
+	 */
+	Prog = Basename (argv[0]);
+	log_set_progname(Prog);
+	log_set_logfd(stderr);
+
+	(void) setlocale (LC_ALL, "");
+	(void) bindtextdomain (PACKAGE, LOCALEDIR);
+	(void) textdomain (PACKAGE);
+
+	process_root_flag ("-R", argc, argv);
+
+	/*
+	 * This command behaves different for root and non-root users.
+	 */
+	amroot = (getuid () == 0);
+
+	OPENLOG ("chsh");
+
+	/* parse the command line options */
+	process_flags (argc, argv);
+
+	/*
+	 * Get the name of the user to check. It is either the command line
+	 * name, or the name getlogin() returns.
+	 */
+	if (optind < argc) {
+		user = argv[optind];
+		pw = xgetpwnam (user);
+		if (NULL == pw) {
+			fprintf (stderr,
+			         _("%s: user '%s' does not exist\n"), Prog, user);
+			fail_exit (1);
+		}
+	} else {
+		pw = get_my_pwent ();
+		if (NULL == pw) {
+			fprintf (stderr,
+			         _("%s: Cannot determine your user name.\n"),
+			         Prog);
+			SYSLOG ((LOG_WARN, "Cannot determine the user name of the caller (UID %lu)",
+			         (unsigned long) getuid ()));
+			fail_exit (1);
+		}
+		user = xstrdup (pw->pw_name);
+	}
+
+#ifdef	USE_NIS
+	/*
+	 * Now we make sure this is a LOCAL password entry for this user ...
+	 */
+	if (__ispwNIS ()) {
+		char *nis_domain;
+		char *nis_master;
+
+		fprintf (stderr,
+		         _("%s: cannot change user '%s' on NIS client.\n"),
+		         Prog, user);
+
+		if (!yp_get_default_domain (&nis_domain) &&
+		    !yp_master (nis_domain, "passwd.byname", &nis_master)) {
+			fprintf (stderr,
+			         _("%s: '%s' is the NIS master for this client.\n"),
+			         Prog, nis_master);
+		}
+		fail_exit (1);
+	}
+#endif
+
+	check_perms (pw);
+
+	/*
+	 * Now get the login shell. Either get it from the password
+	 * file, or use the value from the command line.
+	 */
+	if (!sflg) {
+		STRFCPY (loginsh, pw->pw_shell);
+	}
+
+	/*
+	 * If the login shell was not set on the command line, let the user
+	 * interactively change it.
+	 */
+	if (!sflg) {
+		printf (_("Changing the login shell for %s\n"), user);
+		new_fields ();
+	}
+
+	/*
+	 * Check all of the fields for valid information. The shell
+	 * field may not contain any illegal characters. Non-privileged
+	 * users are restricted to using the shells in /etc/shells.
+	 * The shell must be executable by the user.
+	 */
+	if (valid_field (loginsh, ":,=\n") != 0) {
+		fprintf (stderr, _("%s: Invalid entry: %s\n"), Prog, loginsh);
+		fail_exit (1);
+	}
+	if (   !amroot
+	    && (   is_restricted_shell (loginsh)
+	        || (access (loginsh, X_OK) != 0))) {
+		fprintf (stderr, _("%s: %s is an invalid shell\n"), Prog, loginsh);
+		fail_exit (1);
+	}
+
+	/* Even for root, warn if an invalid shell is specified. */
+	if (access (loginsh, F_OK) != 0) {
+		fprintf (stderr, _("%s: Warning: %s does not exist\n"), Prog, loginsh);
+	} else if (access (loginsh, X_OK) != 0) {
+		fprintf (stderr, _("%s: Warning: %s is not executable\n"), Prog, loginsh);
+	}
+
+	update_shell (user, loginsh);
+
+	SYSLOG ((LOG_INFO, "changed user '%s' shell to '%s'", user, loginsh));
+
+	nscd_flush_cache ("passwd");
+	sssd_flush_cache (SSSD_DB_PASSWD);
+
+	closelog ();
+	exit (E_SUCCESS);
+}
+