From 6b433caed2c86bf41acfa65dd507292e8a0ab2ac Mon Sep 17 00:00:00 2001 From: Leo Famulari Date: Thu, 11 Jan 2018 15:18:04 -0800 Subject: [PATCH] gnu: transmission: Fix a DNS rebinding vulnerability that allows RCE. * gnu/packages/patches/transmission-fix-dns-rebinding-vuln.patch: New file. * gnu/local.mk (dist_patch_DATA): Add it. * gnu/packages/bittorrent.scm (transmission)[source]: Use it. --- gnu/local.mk | 1 + gnu/packages/bittorrent.scm | 1 + .../transmission-fix-dns-rebinding-vuln.patch | 302 ++++++++++++++++++ 3 files changed, 304 insertions(+) create mode 100644 gnu/packages/patches/transmission-fix-dns-rebinding-vuln.patch diff --git a/gnu/local.mk b/gnu/local.mk index 051a9bb656..6af8bfc4bd 100644 --- a/gnu/local.mk +++ b/gnu/local.mk @@ -1105,6 +1105,7 @@ dist_patch_DATA = \ %D%/packages/patches/tipp10-fix-compiling.patch \ %D%/packages/patches/tipp10-remove-license-code.patch \ %D%/packages/patches/tk-find-library.patch \ + %D%/packages/patches/transmission-fix-dns-rebinding-vuln.patch \ %D%/packages/patches/ttf2eot-cstddef.patch \ %D%/packages/patches/ttfautohint-source-date-epoch.patch \ %D%/packages/patches/tophat-build-with-later-seqan.patch \ diff --git a/gnu/packages/bittorrent.scm b/gnu/packages/bittorrent.scm index eca0646200..800a42eea5 100644 --- a/gnu/packages/bittorrent.scm +++ b/gnu/packages/bittorrent.scm @@ -66,6 +66,7 @@ (define-public transmission (uri (string-append "https://transmission.cachefly.net/transmission-" version ".tar.xz")) + (patches (search-patches "transmission-fix-dns-rebinding-vuln.patch")) (sha256 (base32 "0pykmhi7pdmzq47glbj8i2im6iarp4wnj4l1pyvsrnba61f0939s")))) diff --git a/gnu/packages/patches/transmission-fix-dns-rebinding-vuln.patch b/gnu/packages/patches/transmission-fix-dns-rebinding-vuln.patch new file mode 100644 index 0000000000..a3a0cf1608 --- /dev/null +++ b/gnu/packages/patches/transmission-fix-dns-rebinding-vuln.patch @@ -0,0 +1,302 @@ +Fix a weakness that allows remote code execution via the Transmission +RPC server using DNS rebinding: + +https://bugs.chromium.org/p/project-zero/issues/detail?id=1447 + +Patch adapted from Tavis Ormandy's patch on the Transmission master +branch to the Transmission 2.92 release by Leo Famulari +: + +https://github.com/transmission/transmission/pull/468/commits + +From fe2d3c6e75088f3d9b6040ce06da3d530358bc2f Mon Sep 17 00:00:00 2001 +From: Tavis Ormandy +Date: Thu, 11 Jan 2018 10:00:41 -0800 +Subject: [PATCH] mitigate dns rebinding attacks against daemon + +--- + libtransmission/quark.c | 2 + + libtransmission/quark.h | 2 + + libtransmission/rpc-server.c | 116 +++++++++++++++++++++++++++++++++++++---- + libtransmission/rpc-server.h | 4 ++ + libtransmission/session.c | 2 + + libtransmission/transmission.h | 1 + + libtransmission/web.c | 3 ++ + 7 files changed, 121 insertions(+), 9 deletions(-) + +diff --git a/libtransmission/quark.c b/libtransmission/quark.c +index 30cc2bca4..b4fd7aabd 100644 +--- a/libtransmission/quark.c ++++ b/libtransmission/quark.c +@@ -289,6 +289,8 @@ static const struct tr_key_struct my_static[] = + { "rpc-authentication-required", 27 }, + { "rpc-bind-address", 16 }, + { "rpc-enabled", 11 }, ++ { "rpc-host-whitelist", 18 }, ++ { "rpc-host-whitelist-enabled", 26 }, + { "rpc-password", 12 }, + { "rpc-port", 8 }, + { "rpc-url", 7 }, +diff --git a/libtransmission/quark.h b/libtransmission/quark.h +index 7f5212733..17464be8f 100644 +--- a/libtransmission/quark.h ++++ b/libtransmission/quark.h +@@ -291,6 +291,8 @@ enum + TR_KEY_rpc_authentication_required, + TR_KEY_rpc_bind_address, + TR_KEY_rpc_enabled, ++ TR_KEY_rpc_host_whitelist, ++ TR_KEY_rpc_host_whitelist_enabled, + TR_KEY_rpc_password, + TR_KEY_rpc_port, + TR_KEY_rpc_url, +diff --git a/libtransmission/rpc-server.c b/libtransmission/rpc-server.c +index a3485f3fa..292cd5fce 100644 +--- a/libtransmission/rpc-server.c ++++ b/libtransmission/rpc-server.c +@@ -52,6 +52,7 @@ struct tr_rpc_server + bool isEnabled; + bool isPasswordEnabled; + bool isWhitelistEnabled; ++ bool isHostWhitelistEnabled; + tr_port port; + char * url; + struct in_addr bindAddress; +@@ -63,6 +64,7 @@ struct tr_rpc_server + char * password; + char * whitelistStr; + tr_list * whitelist; ++ tr_list * hostWhitelist; + + char * sessionId; + time_t sessionIdExpiresAt; +@@ -588,6 +590,49 @@ isAddressAllowed (const tr_rpc_server * server, const char * address) + return false; + } + ++static bool isHostnameAllowed(tr_rpc_server const* server, struct evhttp_request* req) ++{ ++ /* If password auth is enabled, any hostname is permitted. */ ++ if (server->isPasswordEnabled) ++ { ++ return true; ++ } ++ ++ char const* const host = evhttp_find_header(req->input_headers, "Host"); ++ ++ // If whitelist is disabled, no restrictions. ++ if (!server->isHostWhitelistEnabled) ++ return true; ++ ++ /* No host header, invalid request. */ ++ if (host == NULL) ++ { ++ return false; ++ } ++ ++ /* Host header might include the port. */ ++ char* const hostname = tr_strndup(host, strcspn(host, ":")); ++ ++ /* localhost or ipaddress is always acceptable. */ ++ if (strcmp(hostname, "localhost") == 0 || strcmp(hostname, "localhost.") == 0 || tr_addressIsIP(hostname)) ++ { ++ tr_free(hostname); ++ return true; ++ } ++ ++ /* Otherwise, hostname must be whitelisted. */ ++ for (tr_list* l = server->hostWhitelist; l != NULL; l = l->next) { ++ if (tr_wildmat(hostname, l->data)) ++ { ++ tr_free(hostname); ++ return true; ++ } ++ } ++ ++ tr_free(hostname); ++ return false; ++} ++ + static bool + test_session_id (struct tr_rpc_server * server, struct evhttp_request * req) + { +@@ -663,6 +708,23 @@ handle_request (struct evhttp_request * req, void * arg) + handle_upload (req, server); + } + #ifdef REQUIRE_SESSION_ID ++ else if (!isHostnameAllowed(server, req)) ++ { ++ char* tmp = tr_strdup_printf( ++ "

Transmission received your request, but the hostname was unrecognized.

" ++ "

To fix this, choose one of the following options:" ++ "

    " ++ "
  • Enable password authentication, then any hostname is allowed.
    • " ++ "
  • Add the hostname you want to use to the whitelist in settings.
    • " ++ "

" ++ "

If you're editing settings.json, see the 'rpc-host-whitelist' and 'rpc-host-whitelist-enabled' entries.

" ++ "

This requirement has been added to help prevent " ++ "DNS Rebinding " ++ "attacks.

"); ++ send_simple_response(req, 421, tmp); ++ tr_free(tmp); ++ } ++ + else if (!test_session_id (server, req)) + { + const char * sessionId = get_current_session_id (server); +@@ -674,7 +736,7 @@ handle_request (struct evhttp_request * req, void * arg) + "
  • When you get this 409 error message, resend your request with the updated header" + "

    " + "

    This requirement has been added to help prevent " +- "CSRF " ++ "CSRF " + "attacks.

    " + "

    %s: %s

    ", + TR_RPC_SESSION_ID_HEADER, sessionId); +@@ -875,19 +937,14 @@ tr_rpcGetUrl (const tr_rpc_server * server) + return server->url ? server->url : ""; + } + +-void +-tr_rpcSetWhitelist (tr_rpc_server * server, const char * whitelistStr) ++static void ++tr_rpcSetList (char const* whitelistStr, tr_list** list) + { + void * tmp; + const char * walk; + +- /* keep the string */ +- tmp = server->whitelistStr; +- server->whitelistStr = tr_strdup (whitelistStr); +- tr_free (tmp); +- + /* clear out the old whitelist entries */ +- while ((tmp = tr_list_pop_front (&server->whitelist))) ++ while ((tmp = tr_list_pop_front (list)) != NULL) + tr_free (tmp); + + /* build the new whitelist entries */ +@@ -896,7 +953,7 @@ tr_rpcSetWhitelist (tr_rpc_server * server, const char * whitelistStr) + const char * delimiters = " ,;"; + const size_t len = strcspn (walk, delimiters); + char * token = tr_strndup (walk, len); +- tr_list_append (&server->whitelist, token); ++ tr_list_append (list, token); + if (strcspn (token, "+-") < len) + tr_logAddNamedInfo (MY_NAME, "Adding address to whitelist: %s (And it has a '+' or '-'! Are you using an old ACL by mistake?)", token); + else +@@ -909,6 +966,21 @@ tr_rpcSetWhitelist (tr_rpc_server * server, const char * whitelistStr) + } + } + ++void tr_rpcSetHostWhitelist(tr_rpc_server* server, char const* whitelistStr) ++{ ++ tr_rpcSetList(whitelistStr, &server->hostWhitelist); ++} ++ ++void tr_rpcSetWhitelist(tr_rpc_server* server, char const* whitelistStr) ++{ ++ /* keep the string */ ++ char* const tmp = server->whitelistStr; ++ server->whitelistStr = tr_strdup(whitelistStr); ++ tr_free(tmp); ++ ++ tr_rpcSetList(whitelistStr, &server->whitelist); ++} ++ + const char* + tr_rpcGetWhitelist (const tr_rpc_server * server) + { +@@ -930,6 +1002,11 @@ tr_rpcGetWhitelistEnabled (const tr_rpc_server * server) + return server->isWhitelistEnabled; + } + ++void tr_rpcSetHostWhitelistEnabled(tr_rpc_server* server, bool isEnabled) ++{ ++ server->isHostWhitelistEnabled = isEnabled; ++} ++ + /**** + ***** PASSWORD + ****/ +@@ -1063,6 +1140,28 @@ tr_rpcInit (tr_session * session, tr_variant * settings) + else + tr_rpcSetWhitelistEnabled (s, boolVal); + ++ key = TR_KEY_rpc_host_whitelist_enabled; ++ ++ if (!tr_variantDictFindBool(settings, key, &boolVal)) ++ { ++ missing_settings_key(key); ++ } ++ else ++ { ++ tr_rpcSetHostWhitelistEnabled(s, boolVal); ++ } ++ ++ key = TR_KEY_rpc_host_whitelist; ++ ++ if (!tr_variantDictFindStr(settings, key, &str, NULL) && str != NULL) ++ { ++ missing_settings_key(key); ++ } ++ else ++ { ++ tr_rpcSetHostWhitelist(s, str); ++ } ++ + key = TR_KEY_rpc_authentication_required; + if (!tr_variantDictFindBool (settings, key, &boolVal)) + missing_settings_key (key); +diff --git a/libtransmission/rpc-server.h b/libtransmission/rpc-server.h +index e0302c5ea..8c9e6b24e 100644 +--- a/libtransmission/rpc-server.h ++++ b/libtransmission/rpc-server.h +@@ -49,6 +49,10 @@ void tr_rpcSetWhitelist (tr_rpc_server * server, + + const char* tr_rpcGetWhitelist (const tr_rpc_server * server); + ++void tr_rpcSetHostWhitelistEnabled(tr_rpc_server* server, bool isEnabled); ++ ++void tr_rpcSetHostWhitelist(tr_rpc_server* server, char const* whitelist); ++ + void tr_rpcSetPassword (tr_rpc_server * server, + const char * password); + +diff --git a/libtransmission/session.c b/libtransmission/session.c +index 844cadba8..58b717913 100644 +--- a/libtransmission/session.c ++++ b/libtransmission/session.c +@@ -359,6 +359,8 @@ tr_sessionGetDefaultSettings (tr_variant * d) + tr_variantDictAddStr (d, TR_KEY_rpc_username, ""); + tr_variantDictAddStr (d, TR_KEY_rpc_whitelist, TR_DEFAULT_RPC_WHITELIST); + tr_variantDictAddBool (d, TR_KEY_rpc_whitelist_enabled, true); ++ tr_variantDictAddStr(d, TR_KEY_rpc_host_whitelist, TR_DEFAULT_RPC_HOST_WHITELIST); ++ tr_variantDictAddBool(d, TR_KEY_rpc_host_whitelist_enabled, true); + tr_variantDictAddInt (d, TR_KEY_rpc_port, atoi (TR_DEFAULT_RPC_PORT_STR)); + tr_variantDictAddStr (d, TR_KEY_rpc_url, TR_DEFAULT_RPC_URL_STR); + tr_variantDictAddBool (d, TR_KEY_scrape_paused_torrents_enabled, true); +diff --git a/libtransmission/transmission.h b/libtransmission/transmission.h +index 4f76adfd6..e213a8f4e 100644 +--- a/libtransmission/transmission.h ++++ b/libtransmission/transmission.h +@@ -123,6 +123,7 @@ const char* tr_getDefaultDownloadDir (void); + #define TR_DEFAULT_BIND_ADDRESS_IPV4 "0.0.0.0" + #define TR_DEFAULT_BIND_ADDRESS_IPV6 "::" + #define TR_DEFAULT_RPC_WHITELIST "127.0.0.1" ++#define TR_DEFAULT_RPC_HOST_WHITELIST "" + #define TR_DEFAULT_RPC_PORT_STR "9091" + #define TR_DEFAULT_RPC_URL_STR "/transmission/" + #define TR_DEFAULT_PEER_PORT_STR "51413" +diff --git a/libtransmission/web.c b/libtransmission/web.c +index ee495e9fc..c7f062730 100644 +--- a/libtransmission/web.c ++++ b/libtransmission/web.c +@@ -594,6 +594,7 @@ tr_webGetResponseStr (long code) + case 415: return "Unsupported Media Type"; + case 416: return "Requested Range Not Satisfiable"; + case 417: return "Expectation Failed"; ++ case 421: return "Misdirected Request"; + case 500: return "Internal Server Error"; + case 501: return "Not Implemented"; + case 502: return "Bad Gateway";