From 0d29e379601819c7f7ed8de18b54de803a9f4049 Mon Sep 17 00:00:00 2001

From: Tomas Mraz <tmraz@fedoraproject.org>

Date: Fri, 5 Sep 2014 09:09:37 +0200

Subject: [PATCH] Add grantor field to audit records of libpam.

The grantor field gives audit trail of PAM modules which granted access

for successful return from libpam calls. In case of failed return

the grantor field is set to '?'.

libpam/pam_account.c (pam_acct_mgmt): Remove _pam_auditlog() call.

libpam/pam_auth.c (pam_authenticate, pam_setcred): Likewise.

libpam/pam_password.c (pam_chauthtok): Likewise.

libpam/pam_session.c (pam_open_session, pam_close_session): Likewise.

libpam/pam_audit.c (_pam_audit_writelog): Add grantors parameter,

add grantor= field to the message if grantors is set.

(_pam_list_grantors): New function creating the string with grantors list.

(_pam_auditlog): Add struct handler pointer parameter, call _pam_list_grantors()

to list the grantors from the handler list.

(_pam_audit_end): Add NULL handler parameter to _pam_auditlog() call.

(pam_modutil_audit_write): Add NULL grantors parameter to _pam_audit_writelog().

libpam/pam_dispatch.c (_pam_dispatch_aux): Set h->grantor where appropriate.

(_pam_clear_grantors): New function to clear grantor field of handler.

(_pam_dispatch): Call _pam_clear_grantors() before executing the stack.

Call _pam_auditlog() when appropriate.

libpam/pam_handlers.c (extract_modulename): Do not allow empty module name

or just "?" to avoid confusing audit trail.

(_pam_add_handler): Test for NULL return from extract_modulename().

Clear grantor field of handler.

libpam/pam_private.h: Add grantor field to struct handler, add handler pointer

parameter to _pam_auditlog().

---

 libpam/pam_account.c  |  4 ---

 libpam/pam_audit.c    | 84 +++++++++++++++++++++++++++++++++++++++++++--------

 libpam/pam_auth.c     |  8 -----

 libpam/pam_dispatch.c | 41 ++++++++++++++++++++-----

 libpam/pam_handlers.c | 14 +++++++--

 libpam/pam_password.c |  4 ---

 libpam/pam_private.h  |  3 +-

 libpam/pam_session.c  |  7 -----

 8 files changed, 119 insertions(+), 46 deletions(-)

diff --git a/libpam/pam_account.c b/libpam/pam_account.c

index 572acc4..3a4fb1f 100644

--- a/libpam/pam_account.c

+++ b/libpam/pam_account.c

@@ -19,9 +19,5 @@ int pam_acct_mgmt(pam_handle_t *pamh, int flags)

     retval = _pam_dispatch(pamh, flags, PAM_ACCOUNT);

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_ACCOUNT, retval, flags);

-#endif

-

     return retval;

 }

diff --git a/libpam/pam_audit.c b/libpam/pam_audit.c

index 531746a..24fb799 100644

--- a/libpam/pam_audit.c

+++ b/libpam/pam_audit.c

@@ -6,12 +6,12 @@

    Authors:

    Steve Grubb <sgrubb@redhat.com> */

-#include <stdio.h>

-#include <syslog.h>

 #include "pam_private.h"

 #include "pam_modutil_private.h"

 #ifdef HAVE_LIBAUDIT

+#include <stdio.h>

+#include <syslog.h>

 #include <libaudit.h>

 #include <pwd.h>

 #include <netdb.h>

@@ -25,17 +25,24 @@

 static int

 _pam_audit_writelog(pam_handle_t *pamh, int audit_fd, int type,

-	const char *message, int retval)

+	const char *message, const char *grantors, int retval)

 {

   static int old_errno = -1;

-  int rc;

-  char buf[32];

+  int rc = -ENOMEM;

+  char *buf;

+  const char *grantors_field = " grantors=";

-  snprintf(buf, sizeof(buf), "PAM:%s", message);

+  if (grantors == NULL) {

+      grantors = "";

+      grantors_field = "";

+  }

-  rc = audit_log_acct_message (audit_fd, type, NULL, buf,

-       (retval != PAM_USER_UNKNOWN && pamh->user) ? pamh->user : "?",

-	-1, pamh->rhost, NULL, pamh->tty, retval == PAM_SUCCESS );

+  if (asprintf(&buf, "PAM:%s%s%s", message, grantors_field, grantors) >= 0) {

+      rc = audit_log_acct_message(audit_fd, type, NULL, buf,

+	(retval != PAM_USER_UNKNOWN && pamh->user) ? pamh->user : "?",

+	-1, pamh->rhost, NULL, pamh->tty, retval == PAM_SUCCESS);

+      free(buf);

+  }

   /* libaudit sets errno to his own negative error code. This can be

      an official errno number, but must not. It can also be a audit

@@ -78,12 +85,54 @@ _pam_audit_open(pam_handle_t *pamh)

   return audit_fd;

 }

+static int

+_pam_list_grantors(struct handler *hlist, int retval, char **list)

+{

+  *list = NULL;

+

+  if (retval == PAM_SUCCESS) {

+    struct handler *h;

+    char *p = NULL;

+    size_t len = 0;

+

+    for (h = hlist; h != NULL; h = h->next) {

+      if (h->grantor) {

+        len += strlen(h->mod_name) + 1;

+      }

+    }

+

+    if (len == 0) {

+      return 0;

+    }

+

+    *list = malloc(len);

+    if (*list == NULL) {

+      return -1;

+    }

+

+    for (h = hlist; h != NULL; h = h->next) {

+      if (h->grantor) {

+        if (p == NULL) {

+          p = *list;

+        } else {

+          p = stpcpy(p, ",");

+        }

+

+        p = stpcpy(p, h->mod_name);

+      }

+    }

+  }

+

+  return 0;

+}

+

 int

-_pam_auditlog(pam_handle_t *pamh, int action, int retval, int flags)

+_pam_auditlog(pam_handle_t *pamh, int action, int retval, int flags, struct handler *h)

 {

   const char *message;

   int type;

   int audit_fd;

+  char *grantors;

   if ((audit_fd=_pam_audit_open(pamh)) == -1) {

     return PAM_SYSTEM_ERR;

@@ -134,8 +183,17 @@ _pam_auditlog(pam_handle_t *pamh, int action, int retval, int flags)

     retval = PAM_SYSTEM_ERR;

   }

-  if (_pam_audit_writelog(pamh, audit_fd, type, message, retval) < 0)

+  if (_pam_list_grantors(h, retval, &grantors) < 0) {

+    /* allocation failure */

+    pam_syslog(pamh, LOG_CRIT, "_pam_list_grantors() failed: %m");

     retval = PAM_SYSTEM_ERR;

+  }

+

+  if (_pam_audit_writelog(pamh, audit_fd, type, message,

+      grantors ? grantors : "?", retval) < 0)

+    retval = PAM_SYSTEM_ERR;

+

+  free(grantors);

   audit_close(audit_fd);

   return retval;

@@ -149,7 +207,7 @@ _pam_audit_end(pam_handle_t *pamh, int status UNUSED)

      * stacks having been run. Assume that this is sshd faking

      * things for an unknown user.

      */

-    _pam_auditlog(pamh, _PAM_ACTION_DONE, PAM_USER_UNKNOWN, 0);

+    _pam_auditlog(pamh, _PAM_ACTION_DONE, PAM_USER_UNKNOWN, 0, NULL);

   }

   return 0;

@@ -168,7 +226,7 @@ pam_modutil_audit_write(pam_handle_t *pamh, int type,

     return retval;

   }

-  rc = _pam_audit_writelog(pamh, audit_fd, type, message, retval);

+  rc = _pam_audit_writelog(pamh, audit_fd, type, message, NULL, retval);

   audit_close(audit_fd);

diff --git a/libpam/pam_auth.c b/libpam/pam_auth.c

index 5984fa5..1e7bc6e 100644

--- a/libpam/pam_auth.c

+++ b/libpam/pam_auth.c

@@ -45,10 +45,6 @@ int pam_authenticate(pam_handle_t *pamh, int flags)

     prelude_send_alert(pamh, retval);

 #endif

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_AUTHENTICATE, retval, flags);

-#endif

-

     return retval;

 }

@@ -71,10 +67,6 @@ int pam_setcred(pam_handle_t *pamh, int flags)

     retval = _pam_dispatch(pamh, flags, PAM_SETCRED);

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_SETCRED, retval, flags);

-#endif

-

     D(("pam_setcred exit"));

     return retval;

diff --git a/libpam/pam_dispatch.c b/libpam/pam_dispatch.c

index eb52c82..cf632e8 100644

--- a/libpam/pam_dispatch.c

+++ b/libpam/pam_dispatch.c

@@ -217,8 +217,14 @@ static int _pam_dispatch_aux(pam_handle_t *pamh, int flags, struct handler *h,

                     status = retval;

                 }

 	    }

-	    if ( impression == _PAM_POSITIVE && action == _PAM_ACTION_DONE ) {

-		goto decision_made;

+	    if ( impression == _PAM_POSITIVE ) {

+		if ( retval == PAM_SUCCESS ) {

+		    h->grantor = 1;

+		}

+

+		if ( action == _PAM_ACTION_DONE ) {

+		    goto decision_made;

+		}

 	    }

 	    break;

@@ -262,6 +268,9 @@ static int _pam_dispatch_aux(pam_handle_t *pamh, int flags, struct handler *h,

 			|| (impression == _PAM_POSITIVE

 			    && status == PAM_SUCCESS) ) {

 			if ( retval != PAM_IGNORE || cached_retval == retval ) {

+			    if ( impression == _PAM_UNDEF && retval == PAM_SUCCESS ) {

+				h->grantor = 1;

+			    }

 			    impression = _PAM_POSITIVE;

 			    status = retval;

 			}

@@ -308,6 +317,13 @@ decision_made:     /* by getting  here we have made a decision */

     return status;

 }

+static void _pam_clear_grantors(struct handler *h)

+{

+    for (; h != NULL; h = h->next) {

+	h->grantor = 0;

+    }

+}

+

 /*

  * This function translates the module dispatch request into a pointer

  * to the stack of modules that will actually be run.  the

@@ -318,21 +334,21 @@ decision_made:     /* by getting  here we have made a decision */

 int _pam_dispatch(pam_handle_t *pamh, int flags, int choice)

 {

     struct handler *h = NULL;

-    int retval, use_cached_chain;

+    int retval = PAM_SYSTEM_ERR, use_cached_chain;

     _pam_boolean resumed;

     IF_NO_PAMH("_pam_dispatch", pamh, PAM_SYSTEM_ERR);

     if (__PAM_FROM_MODULE(pamh)) {

 	D(("called from a module!?"));

-	return PAM_SYSTEM_ERR;

+	goto end;

     }

     /* Load all modules, resolve all symbols */

     if ((retval = _pam_init_handlers(pamh)) != PAM_SUCCESS) {

 	pam_syslog(pamh, LOG_ERR, "unable to dispatch function");

-	return retval;

+	goto end;

     }

     use_cached_chain = _PAM_PLEASE_FREEZE;

@@ -360,7 +376,8 @@ int _pam_dispatch(pam_handle_t *pamh, int flags, int choice)

 	break;

     default:

 	pam_syslog(pamh, LOG_ERR, "undefined fn choice; %d", choice);

-	return PAM_ABORT;

+	retval = PAM_ABORT;

+	goto end;

     }

     if (h == NULL) {     /* there was no handlers.conf... entry; will use

@@ -393,11 +410,13 @@ int _pam_dispatch(pam_handle_t *pamh, int flags, int choice)

 	    pam_syslog(pamh, LOG_ERR,

 			    "application failed to re-exec stack [%d:%d]",

 			    pamh->former.choice, choice);

-	    return PAM_ABORT;

+	    retval = PAM_ABORT;

+	    goto end;

 	}

 	resumed = PAM_TRUE;

     } else {

 	resumed = PAM_FALSE;

+	_pam_clear_grantors(h);

     }

     __PAM_TO_MODULE(pamh);

@@ -417,5 +436,13 @@ int _pam_dispatch(pam_handle_t *pamh, int flags, int choice)

 	pamh->former.choice = PAM_NOT_STACKED;

     }

+end:

+

+#ifdef HAVE_LIBAUDIT

+    if (choice != PAM_CHAUTHTOK || flags & PAM_UPDATE_AUTHTOK || retval != PAM_SUCCESS) {

+	retval = _pam_auditlog(pamh, choice, retval, flags, h);

+    }

+#endif

+

     return retval;

 }

diff --git a/libpam/pam_handlers.c b/libpam/pam_handlers.c

index 02714f7..df3a1d9 100644

--- a/libpam/pam_handlers.c

+++ b/libpam/pam_handlers.c

@@ -611,6 +611,12 @@ extract_modulename(const char *mod_path)

   if (dot)

     *dot = '\0';

+  if (*retval == '\0' || strcmp(retval, "?") == 0) {

+    /* do not allow empty module name or "?" to avoid confusing audit trail */

+    _pam_drop(retval);

+    return NULL;

+  }

+

   return retval;

 }

@@ -888,7 +894,9 @@ int _pam_add_handler(pam_handle_t *pamh

     (*handler_p)->cached_retval_p = &((*handler_p)->cached_retval);

     (*handler_p)->argc = argc;

     (*handler_p)->argv = argv;                       /* not a copy */

-    (*handler_p)->mod_name = extract_modulename(mod_path);

+    if (((*handler_p)->mod_name = extract_modulename(mod_path)) == NULL)

+	return PAM_ABORT;

+    (*handler_p)->grantor = 0;

     (*handler_p)->next = NULL;

     /* some of the modules have a second calling function */

@@ -920,7 +928,9 @@ int _pam_add_handler(pam_handle_t *pamh

 	} else {

 	    (*handler_p2)->argv = NULL;              /* no arguments */

 	}

-	(*handler_p2)->mod_name = extract_modulename(mod_path);

+	if (((*handler_p2)->mod_name = extract_modulename(mod_path)) == NULL)

+	    return PAM_ABORT;

+	(*handler_p2)->grantor = 0;

 	(*handler_p2)->next = NULL;

     }

diff --git a/libpam/pam_password.c b/libpam/pam_password.c

index 75db5e5..592e01f 100644

--- a/libpam/pam_password.c

+++ b/libpam/pam_password.c

@@ -57,9 +57,5 @@ int pam_chauthtok(pam_handle_t *pamh, int flags)

 	D(("will resume when ready", retval));

     }

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_CHAUTHTOK, retval, flags);

-#endif

-

     return retval;

 }

diff --git a/libpam/pam_private.h b/libpam/pam_private.h

index 134dc72..d93283c 100644

--- a/libpam/pam_private.h

+++ b/libpam/pam_private.h

@@ -55,6 +55,7 @@ struct handler {

     struct handler *next;

     char *mod_name;

     int stack_level;

+    int grantor;

 };

 #define PAM_HT_MODULE       0

@@ -316,7 +317,7 @@ if ((pamh) == NULL) {                             \

         do { (pamh)->caller_is = _PAM_CALLED_FROM_APP; } while (0)

 #ifdef HAVE_LIBAUDIT

-extern int _pam_auditlog(pam_handle_t *pamh, int action, int retval, int flags);

+extern int _pam_auditlog(pam_handle_t *pamh, int action, int retval, int flags, struct handler *h);

 extern int _pam_audit_end(pam_handle_t *pamh, int pam_status);

 #endif

diff --git a/libpam/pam_session.c b/libpam/pam_session.c

index 512153f..cb393c1 100644

--- a/libpam/pam_session.c

+++ b/libpam/pam_session.c

@@ -22,9 +22,6 @@ int pam_open_session(pam_handle_t *pamh, int flags)

     }

     retval = _pam_dispatch(pamh, flags, PAM_OPEN_SESSION);

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_OPEN_SESSION, retval, flags);

-#endif

     return retval;

 }

@@ -43,10 +40,6 @@ int pam_close_session(pam_handle_t *pamh, int flags)

     retval = _pam_dispatch(pamh, flags, PAM_CLOSE_SESSION);

-#ifdef HAVE_LIBAUDIT

-    retval = _pam_auditlog(pamh, PAM_CLOSE_SESSION, retval, flags);

-#endif

-

     return retval;

 }

-- 

1.8.3.1