waitress: Fingerprint check

Reduces memory usage, protects against 0wned CA's and avoids ca-bundle
confusion.

Closes #175

6 files changed, 32 insertions, 54 deletions

diff --git a/contrib/pianobar.1 b/contrib/pianobar.1
index dbff073..c5d3347 100644
--- a/contrib/pianobar.1
+++ b/contrib/pianobar.1
@@ -282,9 +282,8 @@ sorts by name from a to z, quickmix_01_name_za by type (quickmix at the
 bottom) and name from z to a.
 
 .TP
-.B tls_ca_path = /etc/ssl/certs/ca-certificates.crt
-File that contains the root certificate (and possibly intermediate
-certificates) of Pandora’s CA.
+.B tls_fingerprint = D9980BA2CC0F97BB03822C6211EAEA4A06EEF427
+Hex-encoded SHA1 fingerprint of Pandora’s TLS certificate.
 
 .TP
 .B user = your@user.name
diff --git a/src/libwaitress/waitress.c b/src/libwaitress/waitress.c
index 8bb519a..7082ffd 100644
--- a/src/libwaitress/waitress.c
+++ b/src/libwaitress/waitress.c
@@ -53,21 +53,11 @@ typedef struct {
 	size_t pos;
 } WaitressFetchBufCbBuffer_t;
 
-WaitressReturn_t WaitressInit (WaitressHandle_t *waith, const char *caPath) {
+void WaitressInit (WaitressHandle_t *waith) {
 	assert (waith != NULL);
 
 	memset (waith, 0, sizeof (*waith));
 	waith->timeout = 30000;
-	if (caPath != NULL) {
-		gnutls_certificate_allocate_credentials (&waith->tlsCred);
-		if (gnutls_certificate_set_x509_trust_file (waith->tlsCred, caPath,
-				GNUTLS_X509_FMT_PEM) <= 0) {
-			return WAITRESS_RET_TLS_TRUSTFILE_ERR;
-		}
-		waith->tlsInitialized = true;
-	}
-
-	return WAITRESS_RET_OK;
 }
 
 void WaitressFree (WaitressHandle_t *waith) {
@@ -75,9 +65,6 @@ void WaitressFree (WaitressHandle_t *waith) {
 
 	free (waith->url.url);
 	free (waith->proxy.url);
-	if (waith->tlsInitialized) {
-		gnutls_certificate_free_credentials (waith->tlsCred);
-	}
 	memset (waith, 0, sizeof (*waith));
 }
 
@@ -709,22 +696,10 @@ static int WaitressTlsVerify (gnutls_session_t session) {
 	waith = gnutls_session_get_ptr (session);
 	assert (waith != NULL);
 
-	if (gnutls_certificate_verify_peers2 (session, &status) != GNUTLS_E_SUCCESS) {
-		return GNUTLS_E_CERTIFICATE_ERROR;
-	}
-
-	/* don't accept invalid certs */
-	if (status & (GNUTLS_CERT_INVALID | GNUTLS_CERT_SIGNER_NOT_FOUND |
-			GNUTLS_CERT_REVOKED | GNUTLS_CERT_EXPIRED |
-			GNUTLS_CERT_NOT_ACTIVATED)) {
-		return GNUTLS_E_CERTIFICATE_ERROR;
-	}
-
 	if (gnutls_certificate_type_get (session) != GNUTLS_CRT_X509) {
 		return GNUTLS_E_CERTIFICATE_ERROR;
 	}
 
-	/* check hostname */
 	if ((certList = gnutls_certificate_get_peers (session,
 			&certListSize)) == NULL) {
 		return GNUTLS_E_CERTIFICATE_ERROR;
@@ -739,7 +714,14 @@ static int WaitressTlsVerify (gnutls_session_t session) {
 		return GNUTLS_E_CERTIFICATE_ERROR;
 	}
 
-	if (gnutls_x509_crt_check_hostname (cert, waith->url.host) == 0) {
+	char fingerprint[20];
+	size_t fingerprintSize = sizeof (fingerprint);
+	if (gnutls_x509_crt_get_fingerprint (cert, GNUTLS_DIG_SHA1, fingerprint,
+			&fingerprintSize) != 0) {
+		return GNUTLS_E_CERTIFICATE_ERROR;
+	}
+
+	if (memcmp (fingerprint, waith->tlsFingerprint, sizeof (fingerprint)) != 0) {
 		return GNUTLS_E_CERTIFICATE_ERROR;
 	}
 
@@ -1036,8 +1018,6 @@ WaitressReturn_t WaitressFetchCall (WaitressHandle_t *waith) {
 	waith->request.write = WaitressOrdinaryWrite;
 
 	if (waith->url.tls) {
-		assert (waith->tlsInitialized);
-
 		waith->request.read = WaitressGnutlsRead;
 		waith->request.write = WaitressGnutlsWrite;
 		gnutls_init (&waith->request.tlsSession, GNUTLS_CLIENT);
@@ -1046,6 +1026,7 @@ WaitressReturn_t WaitressFetchCall (WaitressHandle_t *waith) {
 				"PERFORMANCE", &err) != GNUTLS_E_SUCCESS) {
 			return WAITRESS_RET_ERR;
 		}
+		gnutls_certificate_allocate_credentials (&waith->tlsCred);
 		if (gnutls_credentials_set (waith->request.tlsSession,
 				GNUTLS_CRD_CERTIFICATE,
 				waith->tlsCred) != GNUTLS_E_SUCCESS) {
@@ -1083,6 +1064,7 @@ WaitressReturn_t WaitressFetchCall (WaitressHandle_t *waith) {
 	if (waith->url.tls) {
 		gnutls_bye (waith->request.tlsSession, GNUTLS_SHUT_RDWR);
 		gnutls_deinit (waith->request.tlsSession);
+		gnutls_certificate_free_credentials (waith->tlsCred);
 	}
 	close (waith->request.sockfd);
 
diff --git a/src/libwaitress/waitress.h b/src/libwaitress/waitress.h
index e1cf303..7e4401a 100644
--- a/src/libwaitress/waitress.h
+++ b/src/libwaitress/waitress.h
@@ -92,8 +92,8 @@ typedef struct {
 	void *data;
 	WaitressCbReturn_t (*callback) (void *, size_t, void *);
 	int timeout;
+	const char *tlsFingerprint;
 	gnutls_certificate_credentials_t tlsCred;
-	bool tlsInitialized;
 
 	/* per-request data */
 	struct {
@@ -110,7 +110,7 @@ typedef struct {
 	} request;
 } WaitressHandle_t;
 
-WaitressReturn_t WaitressInit (WaitressHandle_t *, const char *);
+void WaitressInit (WaitressHandle_t *);
 void WaitressFree (WaitressHandle_t *);
 bool WaitressSetProxy (WaitressHandle_t *, const char *);
 char *WaitressUrlEncode (const char *);
diff --git a/src/main.c b/src/main.c
index e14a88a..afa75da 100644
--- a/src/main.c
+++ b/src/main.c
@@ -192,7 +192,7 @@ static void BarMainStartPlayback (BarApp_t *app, pthread_t *playerThread) {
 		/* setup player */
 		memset (&app->player, 0, sizeof (app->player));
 
-		WaitressInit (&app->player.waith, NULL);
+		WaitressInit (&app->player.waith);
 		WaitressSetUrl (&app->player.waith, app->playlist->audioUrl);
 
 		/* set up global proxy, player is NULLed on songfinish */
@@ -328,7 +328,6 @@ int main (int argc, char **argv) {
 	static BarApp_t app;
 	/* terminal attributes _before_ we started messing around with ~ECHO */
 	struct termios termOrig;
-	WaitressReturn_t wRet;
 
 	memset (&app, 0, sizeof (app));
 
@@ -355,19 +354,10 @@ int main (int argc, char **argv) {
 				app.settings.keys[BAR_KS_HELP]);
 	}
 
-	if ((wRet = WaitressInit (&app.waith, app.settings.tlsCaPath)) != WAITRESS_RET_OK) {
-		if (wRet == WAITRESS_RET_TLS_TRUSTFILE_ERR) {
-			BarUiMsg (&app.settings, MSG_ERR, "Can't load root certificates. "
-					"Please check the tls_ca_path setting in your config file.\n");
-		} else {
-			BarUiMsg (&app.settings, MSG_ERR, "Can't initialize HTTP library: "
-					"%s\n", WaitressErrorToStr (wRet));
-		}
-		goto die;
-	}
-
+	WaitressInit (&app.waith);
 	app.waith.url.host = strdup (PIANO_RPC_HOST);
 	app.waith.url.tls = true;
+	app.waith.tlsFingerprint = app.settings.tlsFingerprint;
 
 	/* init fds */
 	FD_ZERO(&app.input.set);
@@ -388,7 +378,6 @@ int main (int argc, char **argv) {
 
 	BarMainLoop (&app);
 
-die:
 	if (app.input.fds[1] != -1) {
 		close (app.input.fds[1]);
 	}
diff --git a/src/settings.c b/src/settings.c
index f29fcfa..ee332cc 100644
--- a/src/settings.c
+++ b/src/settings.c
@@ -93,7 +93,6 @@ void BarSettingsDestroy (BarSettings_t *settings) {
 	free (settings->npStationFormat);
 	free (settings->listSongFormat);
 	free (settings->fifo);
-	free (settings->tlsCaPath);
 	for (size_t i = 0; i < MSG_COUNT; i++) {
 		free (settings->msgFormat[i].prefix);
 		free (settings->msgFormat[i].postfix);
@@ -132,7 +131,9 @@ void BarSettingsRead (BarSettings_t *settings) {
 	settings->listSongFormat = strdup ("%i) %a - %t%r");
 	settings->fifo = malloc (PATH_MAX * sizeof (*settings->fifo));
 	BarGetXdgConfigDir (PACKAGE "/ctl", settings->fifo, PATH_MAX);
-	settings->tlsCaPath = strdup ("/etc/ssl/certs/ca-certificates.crt");
+	memcpy (settings->tlsFingerprint, "\xD9\x98\x0B\xA2\xCC\x0F\x97\xBB"
+			"\x03\x82\x2C\x62\x11\xEA\xEA\x4A\x06\xEE\xF4\x27",
+			sizeof (settings->tlsFingerprint));
 
 	settings->msgFormat[MSG_NONE].prefix = NULL;
 	settings->msgFormat[MSG_NONE].postfix = NULL;
@@ -241,9 +242,16 @@ void BarSettingsRead (BarSettings_t *settings) {
 		} else if (streq ("fifo", key)) {
 			free (settings->fifo);
 			settings->fifo = strdup (val);
-		} else if (streq ("tls_ca_path", key)) {
-			free (settings->tlsCaPath);
-			settings->tlsCaPath = strdup (val);
+		} else if (streq ("tls_fingerprint", key)) {
+			/* expects 40 byte hex-encoded sha1 */
+			if (strlen (val) == 40) {
+				for (size_t i = 0; i < 20; i++) {
+					char hex[3];
+					memcpy (hex, &val[i*2], 2);
+					hex[2] = '\0';
+					settings->tlsFingerprint[i] = strtol (hex, NULL, 16);
+				}
+			}
 		} else if (strncmp (formatMsgPrefix, key,
 				strlen (formatMsgPrefix)) == 0) {
 			static const char *mapping[] = {"none", "info", "nowplaying",
diff --git a/src/settings.h b/src/settings.h
index 6cb4cb2..8ce1225 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -96,7 +96,7 @@ typedef struct {
 	char *npStationFormat;
 	char *listSongFormat;
 	char *fifo;
-	char *tlsCaPath;
+	char tlsFingerprint[20];
 	BarMsgFormatStr_t msgFormat[MSG_COUNT];
 } BarSettings_t;