File openvpn-CVE-2024-5594.patch of Package openvpn
--- src.orig/openvpn/buffer.c 2025-01-22 09:11:26.945102537 +0100
+++ src/openvpn/buffer.c 2025-01-22 09:15:18.992145494 +0100
@@ -1113,6 +1113,21 @@
return ret;
}
+bool
+string_check_buf(struct buffer *buf, const unsigned int inclusive, const unsigned int exclusive)
+{
+ ASSERT(buf);
+ for (int i = 0; i < BLEN(buf); i++)
+ {
+ char c = BSTR(buf)[i];
+ if (!char_inc_exc(c, inclusive, exclusive))
+ {
+ return false;
+ }
+ }
+ return true;
+}
+
const char *
string_mod_const(const char *str,
const unsigned int inclusive,
--- src.orig/openvpn/buffer.h 2025-01-22 09:11:26.945102537 +0100
+++ src/openvpn/buffer.h 2025-01-22 09:16:50.090383898 +0100
@@ -944,6 +944,17 @@
bool string_class(const char *str, const unsigned int inclusive, const unsigned int exclusive);
bool string_mod(char *str, const unsigned int inclusive, const unsigned int exclusive, const char replace);
+/**
+ * Check a buffer if it only consists of allowed characters.
+ *
+ * @param buf The buffer to be checked.
+ * @param inclusive The character classes that are allowed.
+ * @param exclusive Character classes that are not allowed even if they are also in inclusive.
+ * @return True if the string consists only of allowed characters, false otherwise.
+ */
+bool
+string_check_buf(struct buffer *buf, const unsigned int inclusive, const unsigned int exclusive);
+
const char *string_mod_const(const char *str,
const unsigned int inclusive,
--- src.orig/openvpn/forward.c 2025-01-22 09:11:26.948102576 +0100
+++ src/openvpn/forward.c 2025-01-22 09:27:02.718712050 +0100
@@ -230,6 +230,52 @@
}
}
+static void
+parse_incoming_control_channel_command(struct context *c, struct buffer *buf)
+{
+ if (buf_string_match_head_str(buf, "AUTH_FAILED"))
+ {
+ receive_auth_failed(c, buf);
+ }
+ else if (buf_string_match_head_str(buf, "PUSH_"))
+ {
+ incoming_push_message(c, buf);
+ }
+ else if (buf_string_match_head_str(buf, "RESTART"))
+ {
+ server_pushed_signal(c, buf, true, 7);
+ }
+ else if (buf_string_match_head_str(buf, "HALT"))
+ {
+ server_pushed_signal(c, buf, false, 4);
+ }
+ else if (buf_string_match_head_str(buf, "INFO_PRE"))
+ {
+ server_pushed_info(c, buf, 8);
+ }
+ else if (buf_string_match_head_str(buf, "INFO"))
+ {
+ server_pushed_info(c, buf, 4);
+ }
+ else if (buf_string_match_head_str(buf, "CR_RESPONSE"))
+ {
+ receive_cr_response(c, buf);
+ }
+ else if (buf_string_match_head_str(buf, "AUTH_PENDING"))
+ {
+ receive_auth_pending(c, buf);
+ }
+ else if (buf_string_match_head_str(buf, "EXIT"))
+ {
+ receive_exit_message(c);
+ }
+ else
+ {
+ msg(D_PUSH_ERRORS, "WARNING: Received unknown control message: %s", BSTR(buf));
+ }
+}
+
+
/*
* Handle incoming configuration
* messages on the control channel.
@@ -245,51 +291,37 @@
struct buffer buf = alloc_buf_gc(len, &gc);
if (tls_rec_payload(c->c2.tls_multi, &buf))
{
- /* force null termination of message */
- buf_null_terminate(&buf);
-
- /* enforce character class restrictions */
- string_mod(BSTR(&buf), CC_PRINT, CC_CRLF, 0);
-
- if (buf_string_match_head_str(&buf, "AUTH_FAILED"))
- {
- receive_auth_failed(c, &buf);
- }
- else if (buf_string_match_head_str(&buf, "PUSH_"))
- {
- incoming_push_message(c, &buf);
- }
- else if (buf_string_match_head_str(&buf, "RESTART"))
- {
- server_pushed_signal(c, &buf, true, 7);
- }
- else if (buf_string_match_head_str(&buf, "HALT"))
- {
- server_pushed_signal(c, &buf, false, 4);
- }
- else if (buf_string_match_head_str(&buf, "INFO_PRE"))
- {
- server_pushed_info(c, &buf, 8);
- }
- else if (buf_string_match_head_str(&buf, "INFO"))
- {
- server_pushed_info(c, &buf, 4);
- }
- else if (buf_string_match_head_str(&buf, "CR_RESPONSE"))
- {
- receive_cr_response(c, &buf);
- }
- else if (buf_string_match_head_str(&buf, "AUTH_PENDING"))
- {
- receive_auth_pending(c, &buf);
- }
- else if (buf_string_match_head_str(&buf, "EXIT"))
- {
- receive_exit_message(c);
- }
- else
+ while (BLEN(&buf) > 1)
{
- msg(D_PUSH_ERRORS, "WARNING: Received unknown control message: %s", BSTR(&buf));
+ /* commands on the control channel are seperated by 0x00 bytes.
+ * cmdlen does not include the 0 byte of the string */
+ int cmdlen = (int)strnlen(BSTR(&buf), BLEN(&buf));
+ if (cmdlen < BLEN(&buf))
+ {
+ /* include the NUL byte and ensure NUL termination */
+ int cmdlen = (int)strlen(BSTR(&buf)) + 1;
+ /* Construct a buffer that only holds the current command and
+ * its closing NUL byte */
+ struct buffer cmdbuf = alloc_buf_gc(cmdlen, &gc);
+ buf_write(&cmdbuf, BPTR(&buf), cmdlen);
+ /* check we have only printable characters or null byte in the
+ * command string and no newlines */
+ if (!string_check_buf(&buf, CC_PRINT | CC_NULL, CC_CRLF))
+ {
+ msg(D_PUSH_ERRORS, "WARNING: Received control with invalid characters: %s",
+ format_hex(BPTR(&buf), BLEN(&buf), 256, &gc));
+ }
+ else
+ {
+ parse_incoming_control_channel_command(c, &cmdbuf);
+ }
+ }
+ else
+ {
+ msg(D_PUSH_ERRORS, "WARNING: Ignoring control channel "
+ "message command without NUL termination");
+ }
+ buf_advance(&buf, cmdlen);
}
}
else
--- tests.orig/unit_tests/openvpn/test_buffer.c 2025-01-22 09:11:56.003473042 +0100
+++ tests/unit_tests/openvpn/test_buffer.c 2025-01-22 09:30:26.633484093 +0100
@@ -259,6 +259,22 @@
gc_free(&gc);
}
+static void
+test_character_string_mod_buf(void **state)
+{
+ struct gc_arena gc = gc_new();
+ struct buffer buf = alloc_buf_gc(1024, &gc);
+ const char test1[] = "There is a nice 1234\x00 year old tree!";
+ buf_write(&buf, test1, sizeof(test1));
+ /* allow the null bytes and string but not the ! */
+ assert_false(string_check_buf(&buf, CC_ALNUM | CC_SPACE | CC_NULL, 0));
+ /* remove final ! and null byte to pass */
+ buf_inc_len(&buf, -2);
+ assert_true(string_check_buf(&buf, CC_ALNUM | CC_SPACE | CC_NULL, 0));
+ /* Check excluding digits works */
+ assert_false(string_check_buf(&buf, CC_ALNUM | CC_SPACE | CC_NULL, CC_DIGIT));
+ gc_free(&gc);
+}
int
main(void)
@@ -289,6 +305,7 @@
cmocka_unit_test(test_buffer_free_gc_one),
cmocka_unit_test(test_buffer_free_gc_two),
cmocka_unit_test(test_buffer_gc_realloc),
+ cmocka_unit_test(test_character_string_mod_buf)
};
return cmocka_run_group_tests_name("buffer", tests, NULL, NULL);
