/*
* Verify established TLS connections.
*
- * Copyright (C) 2011 Simon Ruderich
+ * Copyright (C) 2011-2013 Simon Ruderich
*
* 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
#include "tlsproxy.h"
#include "verify.h"
-/* errno */
+#include <assert.h>
#include <errno.h>
-/* gnutls_x509_*() */
+
#include <gnutls/x509.h>
+static int get_certificate_path(const char *format,
+ const char *hostname, char *buffer, size_t size);
+
+
int verify_tls_connection(gnutls_session_t session, const char *hostname) {
int result;
- char path[1024];
+ char path[TLSPROXY_MAX_PATH_LENGTH];
size_t size;
unsigned int status;
unsigned int cert_list_size;
FILE *file;
char buffer[66]; /* one line in a PEM file is 64 bytes + '\n' + '\0' */
- char server_cert[8192];
- char stored_cert[8192];
+ char server_cert[16384];
+ char stored_cert[16384];
result = gnutls_certificate_verify_peers2(session, &status);
/* Verification failed (!= invalid certificate but worse), no need for any
* more checks. */
- if (0 > result) {
- LOG(LOG_WARNING,
- "verify_tls_connection(): gnutls_certificate_verify_peers2() failed: %s",
+ if (result < 0) {
+ LOG(WARNING,
+ "verify_tls_connection(): "
+ "gnutls_certificate_verify_peers2() failed: %s",
gnutls_strerror(result));
return -1;
}
|| status & GNUTLS_CERT_REVOKED
|| status & GNUTLS_CERT_NOT_ACTIVATED
|| status & GNUTLS_CERT_INSECURE_ALGORITHM) {
- LOG(LOG_WARNING,
- "verify_tls_connection(): invalid server certificate");
+ LOG(WARNING, "verify_tls_connection(): invalid server certificate");
return -1;
}
/* We only handle X509 certificates for now. Let validation fail to
* prevent an attacker from changing the certificate type to prevent
* detection. */
- if (GNUTLS_CRT_X509 != gnutls_certificate_type_get(session)) {
- LOG(LOG_WARNING,
- "verify_tls_connection(): no X509 server certificate");
+ if (gnutls_certificate_type_get(session) != GNUTLS_CRT_X509) {
+ LOG(WARNING, "verify_tls_connection(): no X509 server certificate");
return -1;
}
/* Get server certificate. */
- if (0 > (result = gnutls_x509_crt_init(&cert))) {
- LOG(LOG_WARNING,
+ result = gnutls_x509_crt_init(&cert);
+ if (result < 0) {
+ LOG(WARNING,
"verify_tls_connection(): gnutls_x509_crt_init() failed: %s",
gnutls_strerror(result));
return -1;
}
cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
- if (NULL == cert_list) {
- LOG(LOG_WARNING,
+ if (cert_list == NULL) {
+ LOG(WARNING,
"verify_tls_connection(): gnutls_certificate_get_peers() failed");
gnutls_x509_crt_deinit(cert);
return -1;
}
- if (0 > (result = gnutls_x509_crt_import(cert, &cert_list[0],
- GNUTLS_X509_FMT_DER))) {
- LOG(LOG_WARNING,
+ result = gnutls_x509_crt_import(cert, &cert_list[0], GNUTLS_X509_FMT_DER);
+ if (result < 0) {
+ LOG(WARNING,
"verify_tls_connection(): gnutls_x509_crt_import() failed: %s",
gnutls_strerror(result));
gnutls_x509_crt_deinit(cert);
size = sizeof(server_cert);
result = gnutls_x509_crt_export(cert, GNUTLS_X509_FMT_PEM,
server_cert, &size);
- if (GNUTLS_E_SUCCESS != result) {
- LOG(LOG_WARNING,
+ if (result != GNUTLS_E_SUCCESS) {
+ LOG(WARNING,
"verify_tls_connection(): gnutls_x509_crt_export() failed: %s",
gnutls_strerror(result));
gnutls_x509_crt_deinit(cert);
gnutls_x509_crt_deinit(cert);
/* Open stored server certificate file. */
- if (0 != server_certificate_path(&file, hostname, path, sizeof(path))) {
- LOG(LOG_DEBUG, "server certificate:\n%s", server_cert);
+ if (server_certificate_file(&file, hostname, path, sizeof(path)) != 0) {
+ LOG(DEBUG, "server certificate:\n%s", server_cert);
return -1;
}
size = 1; /* '\0' */
stored_cert[0] = '\0'; /* for strcat() */
- while (NULL != fgets(buffer, sizeof(buffer), file)) {
+ while (fgets(buffer, sizeof(buffer), file) != NULL) {
size += strlen(buffer);
/* Make sure the buffer is big enough. */
- if (sizeof(stored_cert) <= size) {
- LOG(LOG_WARNING, "verify_tls_connection(): '%s' too big", path);
+ if (size >= sizeof(stored_cert)) {
+ LOG(WARNING, "verify_tls_connection(): '%s' too big", path);
fclose(file);
- LOG(LOG_DEBUG, "server certificate:\n%s", server_cert);
+ LOG(DEBUG, "server certificate:\n%s", server_cert);
return -1;
}
strcat(stored_cert, buffer);
}
if (ferror(file)) {
+ LOG(WARNING, "verify_tls_connection(): failed to read from '%s': %s",
+ path, strerror(errno));
fclose(file);
- LOG(LOG_WARNING,
- "verify_tls_connection(): failed to read from '%s': %s",
- path, strerror(errno));
- LOG(LOG_DEBUG, "server certificate:\n%s", server_cert);
+ LOG(DEBUG, "server certificate:\n%s", server_cert);
return -1;
}
fclose(file);
/* Check if the server certificate matches our stored certificate. */
- if (0 != strcmp(stored_cert, server_cert)) {
- LOG(LOG_ERROR,
- "verify_tls_connection(): server certificate changed!",
- path, strerror(errno));
+ if (strcmp(stored_cert, server_cert)) {
+ LOG(ERROR, "verify_tls_connection(): server certificate changed!",
+ path, strerror(errno));
- LOG(LOG_WARNING, "server certificate:\n%s", server_cert);
+ LOG(WARNING, "server certificate:\n%s", server_cert);
return -2;
}
+ /* Check that the proxy certificate file exists and is readable for this
+ * domain. This ensures we send an "invalid" certificate even if the proxy
+ * certificate doesn't exist. */
+ if (proxy_certificate_path(hostname, path, sizeof(path)) != 0) {
+ return -1;
+ }
+ file = fopen(path, "r");
+ if (file == NULL) {
+ LOG(WARNING,
+ "verify_tls_connection(): proxy certificate doesn't exist: '%s'",
+ path);
+ return -1;
+ }
+ fclose(file);
+
return 0;
}
-int server_certificate_path(FILE **file, const char *hostname,
- char *path, size_t size) {
+
+static int get_certificate_path(const char *format,
+ const char *hostname, char *buffer, size_t size) {
+ int result;
+
/* Hostname too long. */
- if (size - strlen(STORED_SERVER_CERT_FORMAT) <= strlen(hostname)) {
- LOG(LOG_WARNING,
- "server_certificate_path(): hostname too long: '%s'",
- hostname);
+ assert(size > strlen(format));
+ if (size - strlen(format) <= strlen(hostname)) {
+ LOG(WARNING, "get_certificate_path(): hostname too long: '%s'",
+ hostname);
return -1;
}
/* Try to prevent path traversals in hostnames. */
- if (NULL != strstr(hostname, "..")) {
- LOG(LOG_WARNING,
- "server_certificate_path(): possible path traversal: '%s'",
- hostname);
+ if (strstr(hostname, "..") != NULL) {
+ LOG(WARNING, "get_certificate_path(): possible path traversal: '%s'",
+ hostname);
+ return -1;
+ }
+ /* Safe as format is no user input. */
+ result = snprintf(buffer, size, format, hostname);
+ if (result < 0) {
+ LOG_PERROR(ERROR, "get_certificate_path(): snprintf failed");
+ return -1;
+ } else if ((size_t)result >= size) {
+ LOG(ERROR, "get_certificate_path(): snprintf buffer too short");
+ return -1;
+ }
+
+ return 0;
+}
+
+int proxy_certificate_path(const char *hostname, char *path, size_t size) {
+ return get_certificate_path(PROXY_SERVER_CERT_FORMAT,
+ hostname, path, size);
+}
+
+int server_certificate_file(FILE **file, const char *hostname,
+ char *path, size_t size) {
+ if (get_certificate_path(STORED_SERVER_CERT_FORMAT,
+ hostname, path, size) != 0) {
+ LOG_PERROR(ERROR, "server_certificate_file(): failed to get path");
return -1;
}
- snprintf(path, size, STORED_SERVER_CERT_FORMAT, hostname);
/* Open the stored certificate file. */
*file = fopen(path, "rb");
- if (NULL == *file) {
+ if (*file == NULL) {
if (global_passthrough_unknown) {
- LOG(LOG_DEBUG,
- "server_certificate_path(): failed to open '%s': %s",
- path, strerror(errno));
+ LOG(DEBUG, "server_certificate_file(): failed to open '%s': %s",
+ path, strerror(errno));
} else {
- LOG(LOG_WARNING,
- "server_certificate_path(): failed to open '%s': %s",
- path, strerror(errno));
+ LOG(WARNING, "server_certificate_file(): failed to open '%s': %s",
+ path, strerror(errno));
}
/* Couldn't open the file, special case. */
return -2;
ruderich.org/simon / tlsproxy / tlsproxy.git / blobdiff