Add new functionality "lock" and "unlock" to provide a simple password

locking mechanism for users. This works by prepending the string
"*LOCKED*" to the password field in master.passwd to prevent successful
decoding.

usr.sbin/pw/pw.c

@@ -35,16 +35,20 @@ static const char rcsid[] =
 #include <sys/wait.h>
 #include "pw.h"
 
-const char     *Modes[] = {"add", "del", "mod", "show", "next", NULL};
+const char     *Modes[] = {
+  "add", "del", "mod", "show", "next",
+  NULL};
 const char     *Which[] = {"user", "group", NULL};
 static const char *Combo1[] = {
   "useradd", "userdel", "usermod", "usershow", "usernext",
+  "lock", "unlock",
   "groupadd", "groupdel", "groupmod", "groupshow", "groupnext",
   NULL};
 static const char *Combo2[] = {
   "adduser", "deluser", "moduser", "showuser", "nextuser",
+  "lock", "unlock",
   "addgroup", "delgroup", "modgroup", "showgroup", "nextgroup",
-NULL};
+  NULL};
 
 struct pwf PWF =
 {
@@ -102,6 +106,8 @@ main(int argc, char *argv[])
 			"V:C:qn:u:rY",
 			"V:C:qn:u:c:d:e:p:g:G:ml:k:s:w:L:h:FNPY",
 			"V:C:qn:u:FPa7",
+			"V:C:q",
+			"V:C:q",
 			"V:C:q"
 		},
 		{ /* grp  */
@@ -272,9 +278,9 @@ static void
 cmdhelp(int mode, int which)
 {
 	if (which == -1)
-		fprintf(stderr, "usage: pw [user|group] [add|del|mod|show|next] [ help | switches/values ]\n");
+		fprintf(stderr, "usage:\n  pw [user|group|lock|unlock] [add|del|mod|show|next] [help|switches/values]\n");
 	else if (mode == -1)
-		fprintf(stderr, "usage: pw %s [add|del|mod|show|next] [ help | switches/values ]\n", Which[which]);
+		fprintf(stderr, "usage:\n  pw %s [add|del|mod|show|next] [help|switches/values]\n", Which[which]);
 	else {
 
 		/*

usr.sbin/pw/pw.h

@@ -50,6 +50,8 @@ enum _mode
         M_UPDATE,
         M_PRINT,
 	M_NEXT,
+	M_LOCK,
+	M_UNLOCK,
         M_NUM
 };
 

usr.sbin/pw/pw_group.c

@@ -60,12 +60,14 @@ pw_group(struct userconf * cnf, int mode, struct cargs * args)
 		NULL
 	};
 
+	if (mode == M_LOCK || mode == M_UNLOCK)
+		errx(EX_USAGE, "'lock' command is not available for groups");
+
 	/*
 	 * With M_NEXT, we only need to return the
 	 * next gid to stdout
 	 */
-	if (mode == M_NEXT)
+	if (mode == M_NEXT) {
-	{
 		gid_t next = gr_gidpolicy(cnf, args);
 		if (getarg(args, 'q'))
 			return next;

usr.sbin/pw/pw_user.c

@@ -55,6 +55,7 @@ static const char rcsid[] =
 #endif
 
 static          int randinit;
+static		char locked_str[] = "*LOCKED*";
 
 static int      print_user(struct passwd * pwd, int pretty, int v7);
 static uid_t    pw_uidpolicy(struct userconf * cnf, struct cargs * args);
@@ -104,6 +105,7 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 {
 	int	        rc;
 	char           *p = NULL;
+	char					 *passtmp;
 	struct carg    *a_name;
 	struct carg    *a_uid;
 	struct carg    *arg;
@@ -127,6 +129,7 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 		0
 	};
 
+
 	/*
 	 * With M_NEXT, we only need to return the
 	 * next uid to stdout
@@ -303,7 +306,8 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 	/*
 	 * Update, delete & print require that the user exists
 	 */
-	if (mode == M_UPDATE || mode == M_DELETE || mode == M_PRINT) {
+	if (mode == M_UPDATE || mode == M_DELETE ||
+	    mode == M_PRINT  || mode == M_LOCK   || mode == M_UNLOCK) {
 		if (a_name == NULL && pwd == NULL)	/* Try harder */
 			pwd = GETPWUID(atoi(a_uid->val));
 
@@ -322,6 +326,31 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 		if (a_name == NULL)	/* May be needed later */
 			a_name = addarg(args, 'n', newstr(pwd->pw_name));
 
+		/*
+		 * The M_LOCK and M_UNLOCK functions simply add or remove
+		 * a "*LOCKED*" prefix from in front of the password to
+		 * prevent it decoding correctly, and therefore prevents
+		 * access. Of course, this only prevents access via
+		 * password authentication (not ssh, kerberos or any
+		 * other method that does not use the UNIX password) but
+		 * that is a known limitation.
+		 */
+
+		if (mode == M_LOCK) {
+			if (strncmp(pwd->pw_passwd, locked_str, sizeof(locked_str)-1) == 0)
+				errx(EX_DATAERR, "user '%s' is already locked", pwd->pw_name);
+			passtmp = malloc(strlen(pwd->pw_passwd) + sizeof(locked_str));
+			if (passtmp == NULL)	/* disaster */
+				errx(EX_UNAVAILABLE, "out of memory");
+			strcpy(passtmp, locked_str);
+			strcat(passtmp, pwd->pw_passwd);
+			pwd->pw_passwd = passtmp;
+		} else if (mode == M_UNLOCK) {
+			if (strncmp(pwd->pw_passwd, locked_str, sizeof(locked_str)-1) != 0)
+				errx(EX_DATAERR, "user '%s' is not locked", pwd->pw_name);
+			pwd->pw_passwd += sizeof(locked_str)-1;
+		}
+
 		/*
 		 * Handle deletions now
 		 */
@@ -563,7 +592,7 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 				warnc(rc, "NIS passwd update");
 			/* NOTE: we treat NIS-only update errors as non-fatal */
 		}
-	} else if (mode == M_UPDATE) {
+	} else if (mode == M_UPDATE || mode == M_LOCK || mode == M_UNLOCK) {
 		rc = chgpwent(a_name->val, pwd);
 		if (rc == -1) {
 			warnx("user '%s' does not exist (NIS?)", pwd->pw_name);