Initial revision

1 files changed, 275 insertions, 0 deletions

diff --git a/modules/pam_wheel/pam_wheel.c b/modules/pam_wheel/pam_wheel.c
new file mode 100644
index 00000000..417fa5b8
--- /dev/null
+++ b/modules/pam_wheel/pam_wheel.c
@@ -0,0 +1,275 @@
+/* pam_wheel module */
+
+/*
+ * Written by Cristian Gafton <gafton@redhat.com> 1996/09/10
+ * See the end of the file for Copyright Information
+ *
+ *
+ * 1.2 - added 'deny' and 'group=' options
+ * 1.1 - added 'trust' option
+ * 1.0 - the code is working for at least another person, so... :-)
+ * 0.1 - use vsyslog instead of vfprintf/syslog in _pam_log
+ *     - return PAM_IGNORE on success (take care of sloppy sysadmins..)
+ *     - use pam_get_user instead of pam_get_item(...,PAM_USER,...)
+ *     - a new arg use_uid to auth the current uid instead of the
+ *       initial (logged in) one.
+ * 0.0 - first release
+ *
+ * TODO:
+ *  - try to use make_remark from pam_unix/support.c
+ *  - consider returning on failure PAM_FAIL_NOW if the user is not
+ *    a wheel member.
+ */
+
+#define _BSD_SOURCE
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <syslog.h>
+#include <stdarg.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+
+/*
+ * here, we make a definition for the externally accessible function
+ * in this file (this definition is required for static a module
+ * but strongly encouraged generally) it is used to instruct the
+ * modules include file to define the function prototypes.
+ */
+
+#define PAM_SM_AUTH
+
+#include <security/pam_modules.h>
+
+/* variables */
+static char use_group[BUFSIZ];
+
+/* some syslogging */
+
+static void _pam_log(int err, const char *format, ...)
+{
+    va_list args;
+
+    va_start(args, format);
+    openlog("PAM-Wheel", LOG_CONS|LOG_PID, LOG_AUTH);
+    vsyslog(err, format, args);
+    va_end(args);
+    closelog();
+}
+
+/* checks if a user is on a list of members of the GID 0 group */
+
+static int is_on_list(char * const *list, const char *member)
+{
+    while (*list) {
+        if (strcmp(*list, member) == 0)
+            return 1;
+        list++;
+    }
+    return 0;
+}
+
+/* argument parsing */
+
+#define PAM_DEBUG_ARG       0x0001
+#define PAM_USE_UID_ARG     0x0002
+#define PAM_TRUST_ARG       0x0004
+#define PAM_DENY_ARG        0x0010  
+
+static int _pam_parse(int argc, const char **argv)
+{
+     int ctrl=0;
+
+     /* step through arguments */
+     for (ctrl=0; argc-- > 0; ++argv) {
+
+          /* generic options */
+
+          if (!strcmp(*argv,"debug"))
+               ctrl |= PAM_DEBUG_ARG;
+          else if (!strcmp(*argv,"use_uid"))
+               ctrl |= PAM_USE_UID_ARG;
+          else if (!strcmp(*argv,"trust"))
+               ctrl |= PAM_TRUST_ARG;
+          else if (!strcmp(*argv,"deny"))
+               ctrl |= PAM_DENY_ARG;
+          else if (!strncmp(*argv,"group=",6))
+                strcpy(use_group,*argv+6);
+          else {
+               _pam_log(LOG_ERR,"pam_parse: unknown option; %s",*argv);
+          }
+     }
+
+     return ctrl;
+}
+
+
+/* --- authentication management functions (only) --- */
+
+PAM_EXTERN
+int pam_sm_authenticate(pam_handle_t *pamh,int flags,int argc
+			,const char **argv)
+{
+     int ctrl;
+     const char *username;
+     char *fromsu;
+     struct passwd *pwd, *tpwd;
+     struct group *grp;
+     int retval = PAM_AUTH_ERR;
+    
+     /* Init the optional group */
+     bzero(use_group,sizeof(use_group));
+     
+     ctrl = _pam_parse(argc, argv);
+     retval = pam_get_user(pamh,&username,NULL);
+     if ((retval != PAM_SUCCESS) || (!username)) {
+        if (ctrl & PAM_DEBUG_ARG)
+            _pam_log(LOG_DEBUG,"can not get the username");
+        return PAM_SERVICE_ERR;
+     }
+
+     /* su to a uid 0 account ? */
+     pwd = getpwnam(username);
+     if (!pwd) {
+        if (ctrl & PAM_DEBUG_ARG)
+            _pam_log(LOG_NOTICE,"unknown user %s",username);
+        return PAM_USER_UNKNOWN;
+     }
+     
+     /* Now we know that the username exists, pass on to other modules...
+      * the call to pam_get_user made this obsolete, so is commented out
+      *
+      * pam_set_item(pamh,PAM_USER,(const void *)username);
+      */
+
+     /* is this user an UID 0 account ? */
+     if(pwd->pw_uid) {
+        /* no need to check for wheel */
+        return PAM_IGNORE;
+     }
+     
+     if (ctrl & PAM_USE_UID_ARG) {
+         tpwd = getpwuid(getuid());
+         if (!tpwd) {
+            if (ctrl & PAM_DEBUG_ARG)
+                _pam_log(LOG_NOTICE,"who is running me ?!");
+            return PAM_SERVICE_ERR;
+         }
+         fromsu = tpwd->pw_name;
+     } else {
+         fromsu = getlogin();
+         if (!fromsu) {
+             if (ctrl & PAM_DEBUG_ARG)
+                _pam_log(LOG_NOTICE,"who is running me ?!");
+             return PAM_SERVICE_ERR;
+         }
+     }
+     
+     if (!use_group[0]) {
+	 if ((grp = getgrnam("wheel")) == NULL) {
+	     grp = getgrgid(0);
+	 }
+     } else
+	 grp = getgrnam(use_group);
+        
+     if (!grp || !grp->gr_mem) {
+        if (ctrl & PAM_DEBUG_ARG) {
+            if (!use_group[0])
+                _pam_log(LOG_NOTICE,"no members in a GID 0 group");
+            else
+                _pam_log(LOG_NOTICE,"no members in '%s' group",use_group);
+        }
+        if (ctrl & PAM_DENY_ARG)
+            /* if this was meant to deny access to the members
+             * of this group and the group does not exist, allow
+             * access
+             */
+            return PAM_IGNORE;
+        else
+            return PAM_AUTH_ERR;
+     }
+        
+     if (is_on_list(grp->gr_mem, fromsu)) {
+        if (ctrl & PAM_DEBUG_ARG)
+            _pam_log(LOG_NOTICE,"Access %s to '%s' for '%s'",
+                     (ctrl & PAM_DENY_ARG)?"denied":"granted",
+                     fromsu,username);
+        if (ctrl & PAM_DENY_ARG)
+            return PAM_PERM_DENIED;
+        else
+            if (ctrl & PAM_TRUST_ARG)
+                return PAM_SUCCESS;
+            else
+                return PAM_IGNORE;
+     }
+
+     if (ctrl & PAM_DEBUG_ARG)
+        _pam_log(LOG_NOTICE,"Access %s for '%s' to '%s'",
+        (ctrl & PAM_DENY_ARG)?"granted":"denied",fromsu,username);
+     if (ctrl & PAM_DENY_ARG)
+        return PAM_SUCCESS;
+     else
+        return PAM_PERM_DENIED;
+}
+
+PAM_EXTERN
+int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc
+		   ,const char **argv)
+{
+     return PAM_SUCCESS;
+}
+
+
+#ifdef PAM_STATIC
+
+/* static module data */
+
+struct pam_module _pam_wheel_modstruct = {
+     "pam_wheel",
+     pam_sm_authenticate,
+     pam_sm_setcred,
+     NULL,
+     NULL,
+     NULL,
+     NULL,
+};
+
+#endif
+
+/*
+ * Copyright (c) Cristian Gafton <gafton@redhat.com>, 1996, 1997
+ *                                              All rights reserved
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, and the entire permission notice in its entirety,
+ *    including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions.  (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED `AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */