Add full PAM support for account management and sessions.

The PAM_FAIL_CHECK and PAM_END macros in su.c came from the util-linux
package's PAM patches to the BSD login.c

Submitted by:	"David J. MacKenzie" <djm@web.us.uu.net>

3 files changed, 230 insertions, 64 deletions

diff --git a/usr.bin/su/Makefile b/usr.bin/su/Makefile
index 99b44fb..c20800d 100644
--- a/usr.bin/su/Makefile
+++ b/usr.bin/su/Makefile
@@ -4,9 +4,18 @@
 PROG=	su
 SRCS=	su.c
 
-COPTS+=	-DLOGIN_CAP -DSKEY
-DPADD=	${LIBUTIL} ${LIBSKEY} ${LIBMD} ${LIBCRYPT}
-LDADD=	-lutil -lskey -lmd -lcrypt
+DPADD+= ${LIBUTIL}
+LDADD+= -lutil
+
+.if !defined(NOPAM)
+CFLAGS+= -DUSE_PAM
+DPADD+= ${LIBPAM}
+LDADD+= ${MINUSLPAM}
+.else
+COPTS+= -DSKEY
+DPADD+= ${LIBSKEY} ${LIBMD} ${LIBCRYPT}
+LDADD+= -lskey -lmd -lcrypt
+.endif
 
 .if defined(WHEELSU)
 COPTS+=	-DWHEELSU
diff --git a/usr.bin/su/su.1 b/usr.bin/su/su.1
index 2be4385..5024849 100644
--- a/usr.bin/su/su.1
+++ b/usr.bin/su/su.1
@@ -173,6 +173,13 @@ to remind one of its awesome power.
 .Bl -tag -width /etc/auth.conf -compact
 .It Pa /etc/auth.conf
 configure authentication services
+.It Pa /etc/pam.conf
+if
+.Nm
+is configured with PAM support, it uses
+.Pa /etc/pam.conf
+entries with service name
+.Dq su
 .El
 .Sh SEE ALSO
 .Xr csh 1 ,
diff --git a/usr.bin/su/su.c b/usr.bin/su/su.c
index 3edacb4..efd46b8 100644
--- a/usr.bin/su/su.c
+++ b/usr.bin/su/su.c
@@ -60,36 +60,47 @@ static const char rcsid[] =
 #include <syslog.h>
 #include <unistd.h>
 #include <libutil.h>
-
-#ifdef LOGIN_CAP
 #include <login_cap.h>
-#endif
 
+#ifdef USE_PAM
+#include <security/pam_appl.h>
+#include <security/pam_misc.h>
+#include <signal.h>
+#include <sys/wait.h>
+
+static int export_pam_environment __P((void));
+static int ok_to_export __P((const char *));
+
+static pam_handle_t *pamh = NULL;
+static char **environ_pam;
+
+#define PAM_END { \
+	if ((retcode = pam_setcred(pamh, PAM_DELETE_CRED)) != PAM_SUCCESS) { \
+		syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, retcode)); \
+	} \
+	if ((retcode = pam_end(pamh,retcode)) != PAM_SUCCESS) { \
+		syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, retcode)); \
+	} \
+}
+#else /* !USE_PAM */
 #ifdef	SKEY
 #include <skey.h>
 #endif
+#endif /* USE_PAM */
 
 #ifdef KERBEROS
 #include <openssl/des.h>
 #include <krb.h>
 #include <netdb.h>
 
-#ifdef LOGIN_CAP
 #define	ARGSTR	"-Kflmc:"
-#else
-#define	ARGSTR	"-Kflm"
-#endif
 
 static int kerberos(char *username, char *user, int uid, char *pword);
 static int koktologin(char *name, char *toname);
 
 int use_kerberos = 1;
 #else /* !KERBEROS */
-#ifdef LOGIN_CAP
 #define	ARGSTR	"-flmc:"
-#else
-#define	ARGSTR	"-flm"
-#endif
 #endif /* KERBEROS */
 
 char   *ontty __P((void));
@@ -107,17 +118,24 @@ main(argc, argv)
 	char *targetpass;
 	int iswheelsu;
 #endif /* WHEELSU */
-	char *p, **g, *user, *shell=NULL, *username, **cleanenv, **nargv, **np;
-	struct group *gr;
+	char *p, *user, *shell=NULL, *username, *cleanenv = NULL, **nargv, **np;
 	uid_t ruid;
 	gid_t gid;
 	int asme, ch, asthem, fastlogin, prio, i;
 	enum { UNSET, YES, NO } iscsh = UNSET;
-#ifdef LOGIN_CAP
 	login_cap_t *lc;
 	char *class=NULL;
 	int setwhat;
-#endif
+#ifdef USE_PAM
+	int retcode;
+	struct pam_conv conv = { misc_conv, NULL };
+	char myhost[MAXHOSTNAMELEN + 1], *mytty;
+	int statusp=0;
+	int child_pid, child_pgrp, ret_pid;
+#else /* !USE_PAM */
+	char **g;
+	struct group *gr;
+#endif /* USE_PAM */
 #ifdef KERBEROS
 	char *k;
 #endif
@@ -147,11 +165,9 @@ main(argc, argv)
 			asme = 1;
 			asthem = 0;
 			break;
-#ifdef LOGIN_CAP
 		case 'c':
 			class = optarg;
 			break;
-#endif
 		case '?':
 		default:
 			usage();
@@ -161,8 +177,7 @@ main(argc, argv)
 		user = argv[optind++];
 
 	if (strlen(user) > MAXLOGNAME - 1) {
-		(void)fprintf(stderr, "su: username too long.\n");
-		exit(1);
+		errx(1, "username too long");
 	}
 		
 	if (user == NULL)
@@ -189,7 +204,7 @@ main(argc, argv)
 	if (errno)
 		prio = 0;
 	(void)setpriority(PRIO_PROCESS, 0, -2);
-	openlog("su", LOG_CONS, 0);
+	openlog("su", LOG_CONS, LOG_AUTH);
 
 	/* get current login name and shell */
 	ruid = getuid();
@@ -214,11 +229,61 @@ main(argc, argv)
 		}
 	}
 
+#ifdef USE_PAM
+	retcode = pam_start("su", user, &conv, &pamh);
+	if (retcode != PAM_SUCCESS) {
+		syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, retcode));
+		errx(1, "pam_start: %s", pam_strerror(pamh, retcode));
+	}
+
+	gethostname(myhost, sizeof(myhost));
+	retcode = pam_set_item(pamh, PAM_RHOST, myhost);
+	if (retcode != PAM_SUCCESS) {
+		syslog(LOG_ERR, "pam_set_item(PAM_RHOST): %s", pam_strerror(pamh, retcode));
+		errx(1, "pam_set_item(PAM_RHOST): %s", pam_strerror(pamh, retcode));
+	}
+
+	mytty = ttyname(STDERR_FILENO);
+	if (!mytty)
+		mytty = "tty";
+	retcode = pam_set_item(pamh, PAM_TTY, mytty);
+	if (retcode != PAM_SUCCESS) {
+		syslog(LOG_ERR, "pam_set_item(PAM_TTY): %s", pam_strerror(pamh, retcode));
+		errx(1, "pam_set_item(PAM_TTY): %s", pam_strerror(pamh, retcode));
+	}
+
+	if (ruid) {
+		retcode = pam_authenticate(pamh, 0);
+		if (retcode != PAM_SUCCESS) {
+			syslog(LOG_ERR, "pam_authenticate: %s", pam_strerror(pamh, retcode));
+			errx(1, "Sorry");
+		}
+
+		if ((retcode = pam_get_item(pamh, PAM_USER, (const void **) &p)) == PAM_SUCCESS) {
+			user = p;
+		} else
+			syslog(LOG_ERR, "pam_get_item(PAM_USER): %s",
+			       pam_strerror(pamh, retcode));
+
+		retcode = pam_acct_mgmt(pamh, 0);
+		if (retcode == PAM_NEW_AUTHTOK_REQD) {
+			retcode = pam_chauthtok(pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
+			if (retcode != PAM_SUCCESS) {
+				syslog(LOG_ERR, "pam_chauthtok: %s", pam_strerror(pamh, retcode));
+				errx(1, "Sorry");
+			}
+		}
+		if (retcode != PAM_SUCCESS) {
+			syslog(LOG_ERR, "pam_acct_mgmt: %s", pam_strerror(pamh, retcode));
+			errx(1, "Sorry");
+		}
+	}
+#endif /* USE_PAM */
+
 	/* get target login information, default to root */
 	if ((pwd = getpwnam(user)) == NULL) {
 		errx(1, "unknown login: %s", user);
 	}
-#ifdef LOGIN_CAP
 	if (class==NULL) {
 		lc = login_getpwclass(pwd);
 	} else {
@@ -228,8 +293,8 @@ main(argc, argv)
 		if (lc == NULL)
 			errx(1, "unknown class: %s", class);
 	}
-#endif
 
+#ifndef USE_PAM
 #ifdef WHEELSU
 	targetpass = strdup(pwd->pw_passwd);
 #endif /* WHEELSU */
@@ -280,18 +345,18 @@ main(argc, argv)
 #ifdef WHEELSU
 			      || (iswheelsu && !strcmp(targetpass, crypt(p,targetpass)))
 #endif /* WHEELSU */
-			      )) {
-#else
+			      ))
+#else /* !SKEY */
 			p = getpass("Password:");
-			if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
-#endif
+			if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd)))
+#endif /* SKEY */
+			{
 #ifdef KERBEROS
 	    			if (!use_kerberos || (use_kerberos && kerberos(username, user, pwd->pw_uid, p)))
 #endif
-					{
-					fprintf(stderr, "Sorry\n");
+				{
 					syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s", username, user, ontty());
-					exit(1);
+					errx(1, "Sorry");
 				}
 			}
 #ifdef WHEELSU
@@ -301,17 +366,17 @@ main(argc, argv)
 #endif /* WHEELSU */
 		}
 		if (pwd->pw_expire && time(NULL) >= pwd->pw_expire) {
-			fprintf(stderr, "Sorry - account expired\n");
 			syslog(LOG_AUTH|LOG_WARNING,
 				"BAD SU %s to %s%s", username,
 				user, ontty());
-			exit(1);
+			errx(1, "Sorry - account expired");
 		}
 	}
+#endif /* USE_PAM */
 
 	if (asme) {
 		/* if asme and non-standard target shell, must be root */
-		if (!chshell(pwd->pw_shell) && ruid)
+		if (ruid && !chshell(pwd->pw_shell))
 			errx(1, "permission denied (shell).");
 	} else if (pwd->pw_shell && *pwd->pw_shell) {
 		shell = pwd->pw_shell;
@@ -334,7 +399,49 @@ main(argc, argv)
 
 	(void)setpriority(PRIO_PROCESS, 0, prio);
 
-#ifdef LOGIN_CAP
+	/*
+	 * PAM modules might add supplementary groups in
+	 * pam_setcred(), so initialize them first.
+	 */
+	if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) < 0)
+		err(1, "setusercontext");
+
+#ifdef USE_PAM
+	retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
+	if (retcode != PAM_SUCCESS) {
+		syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, retcode));
+	}
+
+	/*
+	 * We must fork() before setuid() because we need to call
+	 * pam_setcred(pamh, PAM_DELETE_CRED) as root.
+	 */
+
+	statusp = 1;
+	switch ((child_pid = fork())) {
+	default:
+            while ((ret_pid = waitpid(child_pid, &statusp, WUNTRACED)) != -1) {
+		if (WIFSTOPPED(statusp)) {
+		    child_pgrp = tcgetpgrp(1);
+		    kill(getpid(), SIGSTOP);
+		    tcsetpgrp(1, child_pgrp);
+		    kill(child_pid, SIGCONT); 
+		    statusp = 1;
+		    continue;
+		}
+		break;
+            }
+	    if (ret_pid == -1)
+		err(1, "waitpid");
+	    PAM_END;
+	    exit(statusp);
+	case -1:
+	    err(1, "fork");
+	    PAM_END;
+	    exit (1);
+	case 0:
+#endif /* USE_PAM */
+
 	/*
 	 * Set all user context except for:
 	 *   Environmental variables
@@ -343,7 +450,7 @@ main(argc, argv)
 	 *   Path
 	 */
 	setwhat =  LOGIN_SETALL & ~(LOGIN_SETENV | LOGIN_SETUMASK |
-	    LOGIN_SETLOGIN | LOGIN_SETPATH);
+	    LOGIN_SETLOGIN | LOGIN_SETPATH | LOGIN_SETGROUP);
 
 	/*
 	 * Don't touch resource/priority settings if -m has been
@@ -353,15 +460,6 @@ main(argc, argv)
 		setwhat &= ~(LOGIN_SETPRIORITY|LOGIN_SETRESOURCES);
 	if (setusercontext(lc, pwd, pwd->pw_uid, setwhat) < 0)
 		err(1, "setusercontext");
-#else
-	/* set permissions */
-	if (setgid(pwd->pw_gid) < 0)
-		err(1, "setgid");
-	if (initgroups(user, pwd->pw_gid))
-		errx(1, "initgroups failed");
-	if (setuid(pwd->pw_uid) < 0)
-		err(1, "setuid");
-#endif
 
 	if (!asme) {
 		if (asthem) {
@@ -369,16 +467,20 @@ main(argc, argv)
 #ifdef KERBEROS
 			k = getenv("KRBTKFILE");
 #endif
-			if ((cleanenv = calloc(20, sizeof(char*))) == NULL)
-				errx(1, "calloc");
-			cleanenv[0] = NULL;
-			environ = cleanenv;
-#ifdef LOGIN_CAP
+			environ = &cleanenv;
+
+#ifdef USE_PAM
+			/*
+			 * Add any environmental variables that the
+			 * PAM modules may have set.
+			 */
+			environ_pam = pam_getenvlist(pamh);
+			if (environ_pam)
+				export_pam_environment();
+#endif /* USE_PAM */
+
 			/* set the su'd user's environment & umask */
 			setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK|LOGIN_SETENV);
-#else
-			(void)setenv("PATH", _PATH_DEFPATH, 1);
-#endif
 			if (p)
 				(void)setenv("TERM", p, 1);
 #ifdef KERBEROS
@@ -393,6 +495,9 @@ main(argc, argv)
 		(void)setenv("HOME", pwd->pw_dir, 1);
 		(void)setenv("SHELL", shell, 1);
 	}
+
+	login_close(lc);
+
 	if (iscsh == YES) {
 		if (fastlogin)
 			*np-- = "-f";
@@ -404,20 +509,65 @@ main(argc, argv)
 	*np = asthem ? "-su" : iscsh == YES ? "_su" : "su";
 
 	if (ruid != 0)
-		syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
+		syslog(LOG_NOTICE, "%s to %s%s",
 		    username, user, ontty());
 
-	login_close(lc);
-
 	execv(shell, np);
 	err(1, "%s", shell);
+#ifdef USE_PAM
+	}
+#endif /* USE_PAM */
+}
+
+#ifdef USE_PAM
+static int
+export_pam_environment()
+{
+	char	**pp;
+
+	for (pp = environ_pam; *pp != NULL; pp++) {
+		if (ok_to_export(*pp))
+			(void) putenv(*pp);
+		free(*pp);
+	}
+	return PAM_SUCCESS;
+}
+
+/*
+ * Sanity checks on PAM environmental variables:
+ * - Make sure there is an '=' in the string.
+ * - Make sure the string doesn't run on too long.
+ * - Do not export certain variables.  This list was taken from the
+ *   Solaris pam_putenv(3) man page.
+ */
+static int
+ok_to_export(s)
+	const char *s;
+{
+	static const char *noexport[] = {
+		"SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH",
+		"IFS", "PATH", NULL
+	};
+	const char **pp;
+	size_t n;
+
+	if (strlen(s) > 1024 || strchr(s, '=') == NULL)
+		return 0;
+	if (strncmp(s, "LD_", 3) == 0)
+		return 0;
+	for (pp = noexport; *pp != NULL; pp++) {
+		n = strlen(*pp);
+		if (s[n] == '=' && strncmp(s, *pp, n) == 0)
+			return 0;
+	}
+	return 1;
 }
+#endif /* USE_PAM */
 
 static void
 usage()
 {
-	(void)fprintf(stderr, "usage: su [%s] [login [args]]\n", ARGSTR);
-	exit(1);
+	errx(1, "usage: su [%s] [login [args]]", ARGSTR);
 }
 
 int
@@ -501,7 +651,7 @@ kerberos(username, user, uid, pword)
 			return (1);
 		}
 		warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
-		syslog(LOG_NOTICE|LOG_AUTH,
+		syslog(LOG_NOTICE,
 		    "BAD Kerberos SU: %s to %s%s: %s",
 		    username, user, ontty(), krb_err_txt[kerno]);
 		return (1);
@@ -528,13 +678,13 @@ kerberos(username, user, uid, pword)
 
 	if (kerno == KDC_PR_UNKNOWN) {
 		warnx("Warning: TGT not verified.");
-		syslog(LOG_NOTICE|LOG_AUTH,
+		syslog(LOG_NOTICE,
 		    "%s to %s%s, TGT not verified (%s); %s.%s not registered?",
 		    username, user, ontty(), krb_err_txt[kerno],
 		    "rcmd", savehost);
 	} else if (kerno != KSUCCESS) {
 		warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
-		syslog(LOG_NOTICE|LOG_AUTH, "failed su: %s to %s%s: %s",
+		syslog(LOG_NOTICE, "failed su: %s to %s%s: %s",
 		    username, user, ontty(), krb_err_txt[kerno]);
 		dest_tkt();
 		return (1);
@@ -548,9 +698,9 @@ kerberos(username, user, uid, pword)
 
 		if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
 		    &authdata, "")) != KSUCCESS) {
-			warnx("kerberos: unable to verify rcmd ticket: %s\n",
+			warnx("kerberos: unable to verify rcmd ticket: %s",
 			    krb_err_txt[kerno]);
-			syslog(LOG_NOTICE|LOG_AUTH,
+			syslog(LOG_NOTICE,
 			    "failed su: %s to %s%s: %s", username,
 			     user, ontty(), krb_err_txt[kerno]);
 			dest_tkt();