pam_wrapper/fix-pam-module-output-crash.patch

From 00fc7d7151408e53728a0df8868ad75dc0c00a7d Mon Sep 17 00:00:00 2001
From: Bastien Nocera <hadess@hadess.net>
Date: Wed, 22 Jan 2020 11:50:37 +0100
Subject: [PATCH 1/4] python: Fix crash when the PAM module outputs too much
 data

This code expected each input (whether echo on or echo off input),
to generate at most one info or error output, which is obviously not
correct. A PAM module with external inputs can throw dozens of messages
and warnings even if the only expected input is a password.

Allocate those placeholder arrays to be as big as possible to accomodate
chatty PAM modules.

Closes: https://bugzilla.samba.org/show_bug.cgi?id=14245

Signed-off-by: Bastien Nocera <hadess@hadess.net>
---
 src/python/pypamtest.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/python/pypamtest.c b/src/python/pypamtest.c
index 905c652..c4d0b07 100644
--- a/src/python/pypamtest.c
+++ b/src/python/pypamtest.c
@@ -852,8 +852,8 @@ static int fill_conv_data(PyObject *py_echo_off,
 		return ENOMEM;
 	}
 
-	conv_data->out_info = new_conv_list(conv_count);
-	conv_data->out_err = new_conv_list(conv_count);
+	conv_data->out_info = new_conv_list(PAM_CONV_MSG_MAX);
+	conv_data->out_err = new_conv_list(PAM_CONV_MSG_MAX);
 	if (conv_data->out_info == NULL || conv_data->out_err == NULL) {
 		free_conv_data(conv_data);
 		return ENOMEM;
-- 
2.24.1


From e106274e4195aa3bc5f87d469c5555764b3becf0 Mon Sep 17 00:00:00 2001
From: Bastien Nocera <hadess@hadess.net>
Date: Wed, 22 Jan 2020 12:17:03 +0100
Subject: [PATCH 2/4] modules: Add pam_chatty module

Add a simple PAM module that will output "num_lines" lines of PAM info
and/or error output.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
---
 src/modules/CMakeLists.txt |   2 +-
 src/modules/pam_chatty.c   | 176 +++++++++++++++++++++++++++++++++++++
 2 files changed, 177 insertions(+), 1 deletion(-)
 create mode 100644 src/modules/pam_chatty.c

diff --git a/src/modules/CMakeLists.txt b/src/modules/CMakeLists.txt
index 8e13a0b..e956f4c 100644
--- a/src/modules/CMakeLists.txt
+++ b/src/modules/CMakeLists.txt
@@ -1,6 +1,6 @@
 project(pam_wrapper-modules C)
 
-set(PAM_MODULES pam_matrix pam_get_items pam_set_items)
+set(PAM_MODULES pam_matrix pam_get_items pam_set_items pam_chatty)
 
 set(PAM_LIBRARIES pam)
 if (HAVE_PAM_MISC)
diff --git a/src/modules/pam_chatty.c b/src/modules/pam_chatty.c
new file mode 100644
index 0000000..5ffed5c
--- /dev/null
+++ b/src/modules/pam_chatty.c
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2015 Andreas Schneider <asn@samba.org>
+ * Copyright (c) 2015 Jakub Hrozek <jakub.hrozek@posteo.se>
+ * Copyright (c) 2020 Bastien Nocera <hadess@hadess.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <pwd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <stdint.h>
+
+#ifndef discard_const
+#define discard_const(ptr) ((void *)((uintptr_t)(ptr)))
+#endif
+
+#ifndef discard_const_p
+#define discard_const_p(type, ptr) ((type *)discard_const(ptr))
+#endif
+
+#ifdef HAVE_SECURITY_PAM_APPL_H
+#include <security/pam_appl.h>
+#endif
+#ifdef HAVE_SECURITY_PAM_MODULES_H
+#include <security/pam_modules.h>
+#endif
+#ifdef HAVE_SECURITY_PAM_EXT_H
+#include <security/pam_ext.h>
+#endif
+
+#include "pwrap_compat.h"
+
+#define VERBOSE_KEY	"verbose"
+#define ERROR_KEY	"error"
+#define INFO_KEY	"info"
+#define NUM_LINES_KEY	"num_lines="
+
+#define DEFAULT_NUM_LINES 3
+
+/* We only return up to 16 messages from the PAM conversation.
+ * Value from src/python/pypamtest.c */
+#define PAM_CONV_MSG_MAX        16
+
+#define PAM_CHATTY_FLG_VERBOSE	(1 << 0)
+#define PAM_CHATTY_FLG_ERROR	(1 << 1)
+#define PAM_CHATTY_FLG_INFO	(1 << 1)
+
+#ifndef discard_const
+#define discard_const(ptr) ((void *)((uintptr_t)(ptr)))
+#endif
+
+#ifndef discard_const_p
+#define discard_const_p(type, ptr) ((type *)discard_const(ptr))
+#endif
+
+static int pam_chatty_conv(pam_handle_t *pamh,
+			   const int msg_style,
+			   const char *msg)
+{
+	int ret;
+	const struct pam_conv *conv;
+	const struct pam_message *mesg[1];
+	struct pam_response *r;
+	struct pam_message *pam_msg;
+
+	ret = pam_get_item(pamh, PAM_CONV, (const void **) &conv);
+	if (ret != PAM_SUCCESS) {
+		return ret;
+	}
+
+	pam_msg = malloc(sizeof(struct pam_message));
+	if (pam_msg == NULL) {
+		return PAM_BUF_ERR;
+	}
+
+	pam_msg->msg_style = msg_style;
+	pam_msg->msg = discard_const_p(char, msg);
+
+	mesg[0] = (const struct pam_message *) pam_msg;
+	ret = conv->conv(1, mesg, &r, conv->appdata_ptr);
+	free(pam_msg);
+
+	return ret;
+}
+
+/* Evaluate command line arguments and store info about them in the
+ * pam_matrix context
+ */
+static unsigned int parse_args(int argc,
+			       const char *argv[],
+			       unsigned int *num_lines)
+{
+	unsigned int flags = 0;
+
+	*num_lines = DEFAULT_NUM_LINES;
+
+	for (; argc-- > 0; ++argv) {
+		if (strncmp(*argv, NUM_LINES_KEY, strlen(NUM_LINES_KEY)) == 0) {
+			if (*(*argv+strlen(NUM_LINES_KEY)) != '\0') {
+				*num_lines = atoi(*argv+strlen(NUM_LINES_KEY));
+				if (*num_lines <= DEFAULT_NUM_LINES)
+					*num_lines = DEFAULT_NUM_LINES;
+				if (*num_lines > PAM_CONV_MSG_MAX)
+					*num_lines = PAM_CONV_MSG_MAX;
+			}
+		} else if (strncmp(*argv, VERBOSE_KEY,
+				   strlen(VERBOSE_KEY)) == 0) {
+			flags |= PAM_CHATTY_FLG_VERBOSE;
+		} else if (strncmp(*argv, ERROR_KEY,
+				   strlen(ERROR_KEY)) == 0) {
+			flags |= PAM_CHATTY_FLG_ERROR;
+		} else if (strncmp(*argv, INFO_KEY,
+				   strlen(INFO_KEY)) == 0) {
+			flags |= PAM_CHATTY_FLG_INFO;
+		}
+	}
+
+	return flags;
+}
+
+PAM_EXTERN int
+pam_sm_authenticate(pam_handle_t *pamh, int flags,
+		    int argc, const char *argv[])
+{
+	unsigned int optflags, num_lines;
+
+	optflags = parse_args (argc, argv, &num_lines);
+	if (!(optflags & PAM_CHATTY_FLG_VERBOSE))
+		return PAM_SUCCESS;
+
+	if (optflags & PAM_CHATTY_FLG_INFO) {
+		unsigned int i;
+
+		for (i = 0; i < num_lines; i++) {
+			pam_chatty_conv(pamh,
+					PAM_TEXT_INFO,
+					"Authentication succeeded");
+		}
+	}
+
+	if (optflags & PAM_CHATTY_FLG_ERROR) {
+		unsigned int i;
+
+		for (i = 0; i < num_lines; i++) {
+			pam_chatty_conv(pamh,
+					PAM_ERROR_MSG,
+					"Authentication generated an error");
+		}
+	}
+
+	return PAM_SUCCESS;
+}
-- 
2.24.1


From 348ee7d7fe2e426bc099347b37357710e4f1cf47 Mon Sep 17 00:00:00 2001
From: Bastien Nocera <hadess@hadess.net>
Date: Wed, 22 Jan 2020 12:21:05 +0100
Subject: [PATCH 3/4] tests: Add service file for chatty module

So we can test it.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
---
 tests/CMakeLists.txt     | 3 +++
 tests/services/chatty.in | 1 +
 2 files changed, 4 insertions(+)
 create mode 100644 tests/services/chatty.in

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 997c15e..eb0477c 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -22,6 +22,9 @@ configure_file(services/matrix_py.in ${CMAKE_CURRENT_BINARY_DIR}/services/matrix
 
 configure_file(services/pwrap_get_set.in ${CMAKE_CURRENT_BINARY_DIR}/services/pwrap_get_set @ONLY)
 
+set(PAM_CHATTY_PATH "${CMAKE_BINARY_DIR}/src/modules/pam_chatty.so")
+configure_file(services/chatty.in ${CMAKE_CURRENT_BINARY_DIR}/services/chatty @ONLY)
+
 if (OSX)
 	set(TEST_ENVIRONMENT DYLD_FORCE_FLAT_NAMESPACE=1;DYLD_INSERT_LIBRARIES=${PAM_WRAPPER_LOCATION};PAM_WRAPPER=1;PAM_WRAPPER_SERVICE_DIR=${CMAKE_CURRENT_BINARY_DIR}/services})
 	add_definitions(-DOSX)
diff --git a/tests/services/chatty.in b/tests/services/chatty.in
new file mode 100644
index 0000000..0099b50
--- /dev/null
+++ b/tests/services/chatty.in
@@ -0,0 +1 @@
+auth		required	@PAM_CHATTY_PATH@ verbose num_lines=16 info error
-- 
2.24.1


From 3a130534011d4d13399cc7626a0a2b92e90e1ab6 Mon Sep 17 00:00:00 2001
From: Bastien Nocera <hadess@hadess.net>
Date: Wed, 22 Jan 2020 12:22:30 +0100
Subject: [PATCH 4/4] tests: Add test for verbose PAM modules

Signed-off-by: Bastien Nocera <hadess@hadess.net>
---
 tests/pypamtest_test.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/pypamtest_test.py b/tests/pypamtest_test.py
index 32ef65d..db66490 100755
--- a/tests/pypamtest_test.py
+++ b/tests/pypamtest_test.py
@@ -115,6 +115,11 @@ class PyPamTestRunTest(unittest.TestCase):
         self.assertSequenceEqual(res.info, (u'Authentication succeeded',))
         self.assertSequenceEqual(res.errors, ())
 
+    def test_run_chatty_auth(self):
+        neo_password = "secret"
+        tc = pypamtest.TestCase(pypamtest.PAMTEST_AUTHENTICATE)
+        res = pypamtest.run_pamtest("neo", "chatty", [tc], [ neo_password ])
+
     def test_repr(self):
         tc = pypamtest.TestCase(pypamtest.PAMTEST_CHAUTHTOK, 1, 2)
         r = repr(tc)
-- 
2.24.1