pam_krb5/pam_krb5-2.2.11-1-refresh-drop-restore-priv.dif

Index: src/auth.c
===================================================================
--- src/auth.c.orig
+++ src/auth.c
@@ -480,9 +480,13 @@ pam_sm_setcred(pam_handle_t *pamh, int f
 		return pam_sm_open_session(pamh, flags, argc, argv);
 	}
 	if (flags & (PAM_REINITIALIZE_CRED | PAM_REFRESH_CRED)) {
-		if (_pam_krb5_sly_looks_unsafe() == 0) {
+		int unsave = _pam_krb5_sly_looks_unsafe();
+
+		/* unsave == 2 or 3 can be fixed inside of
+		   _pam_krb5_sly_maybe_refresh */
+		if (unsave == 0 || unsave == 2 || unsave == 3) {
 			return _pam_krb5_sly_maybe_refresh(pamh, flags,
-							   argc, argv);
+			                                   argc, argv);
 		} else {
 			return PAM_IGNORE;
 		}
Index: src/sly.c
===================================================================
--- src/sly.c.orig
+++ src/sly.c
@@ -148,6 +148,21 @@ _pam_krb5_sly_looks_unsafe(void)
 	return 0;
 }
 
+/* restore dropped privileges */
+int
+_restore_privs(uid_t save_euid, gid_t save_egid)
+{
+	int retuid = 0, retgid = 0;
+	
+	retuid = setresuid(getuid(), save_euid, getuid());
+	retgid = setresgid(getgid(), save_egid, getgid());
+	
+	/* debug("restore privileges: UID = %u, EUID = %u\n", getuid(), geteuid()); */
+	/* debug("restore privileges: GID = %u, EGID = %u\n", getgid(), getegid()); */
+	
+	return (retuid == -1 || retgid == -1)?-1:0;
+}
+
 int
 _pam_krb5_sly_maybe_refresh(pam_handle_t *pamh, int flags,
 			    int argc, PAM_KRB5_MAYBE_CONST char **argv)
@@ -163,6 +178,23 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 	gid_t gid;
 	char *v5ccname, *v5filename, *v4tktfile;
 
+	uid_t save_euid = geteuid();
+	gid_t save_egid = getegid();
+	
+
+	if(_pam_krb5_sly_looks_unsafe() == 2 || _pam_krb5_sly_looks_unsafe() == 3)
+	{
+		/* debug("current privileges: UID = %u, EUID = %u\n", getuid(), geteuid()); */
+		/* debug("current privileges: GID = %u, EGID = %u\n", getgid(), getegid()); *(
+
+		/* drop privileges temporarily; restore them on every return from this function */
+		setresuid(getuid(), getuid(), geteuid());
+		setresgid(getgid(), getgid(), getegid());
+		
+		/* debug("drop privileges temporarily: UID = %u, EUID = %u\n", getuid(), geteuid()); */
+		/* debug("drop privileges temporarily: GID = %u, EGID = %u\n", getgid(), getegid()); */
+	}
+
 	/* Inexpensive checks. */
 	switch (_pam_krb5_sly_looks_unsafe()) {
 	case 0:
@@ -170,18 +202,22 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 		break;
 	case 1:
 		warn("won't refresh credentials while running under sudo");
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 		break;
 	case 2:
 		warn("won't refresh credentials while running setuid");
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 		break;
 	case 3:
 		warn("won't refresh credentials while running setgid");
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 		break;
 	default:
 		warn("not safe to refresh credentials");
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 		break;
 	}
@@ -189,6 +225,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 	/* Initialize Kerberos. */
 	if (_pam_krb5_init_ctx(&ctx, argc, argv) != 0) {
 		warn("error initializing Kerberos");
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 	}
 
@@ -197,6 +234,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 	if (i != PAM_SUCCESS) {
 		warn("could not identify user name");
 		krb5_free_context(ctx);
+		_restore_privs(save_euid, save_egid);
 		return i;
 	}
 
@@ -205,6 +243,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 	if (options == NULL) {
 		warn("error parsing options (shouldn't happen)");
 		krb5_free_context(ctx);
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 	}
 	if (options->debug) {
@@ -226,6 +265,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 		}
 		_pam_krb5_options_free(pamh, ctx, options);
 		krb5_free_context(ctx);
+		_restore_privs(save_euid, save_egid);
 		return retval;
 	}
 
@@ -238,6 +278,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 		_pam_krb5_user_info_free(ctx, userinfo);
 		_pam_krb5_options_free(pamh, ctx, options);
 		krb5_free_context(ctx);
+		_restore_privs(save_euid, save_egid);
 		return PAM_IGNORE;
 	}
 
@@ -249,6 +290,7 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 		_pam_krb5_user_info_free(ctx, userinfo);
 		_pam_krb5_options_free(pamh, ctx, options);
 		krb5_free_context(ctx);
+		_restore_privs(save_euid, save_egid);
 		return PAM_SERVICE_ERR;
 	}
 
@@ -360,5 +402,6 @@ _pam_krb5_sly_maybe_refresh(pam_handle_t
 	_pam_krb5_options_free(pamh, ctx, options);
 	krb5_free_context(ctx);
 
+	_restore_privs(save_euid, save_egid);
 	return retval;
 }