diff options
| -rw-r--r-- | changes/29241_diagnostic | 4 | ||||
| -rw-r--r-- | changes/bug29241 | 6 | ||||
| -rw-r--r-- | src/lib/tls/tortls_nss.c | 40 |
3 files changed, 50 insertions, 0 deletions
diff --git a/changes/29241_diagnostic b/changes/29241_diagnostic new file mode 100644 index 0000000000..1e38654957 --- /dev/null +++ b/changes/29241_diagnostic @@ -0,0 +1,4 @@ + o Minor features (NSS, diagnostic): + - Try to log an error from NSS (if there is any) and a more useful + description of our situation if we are using NSS and a call to + SSL_ExportKeyingMaterial() fails. Diagnostic for ticket 29241. diff --git a/changes/bug29241 b/changes/bug29241 new file mode 100644 index 0000000000..7f25e154d1 --- /dev/null +++ b/changes/bug29241 @@ -0,0 +1,6 @@ + o Major bugfixes (NSS, relay): + - When running with NSS, disable TLS 1.2 ciphersuites that use SHA384 + for their PRF. Due to an NSS bug, the TLS key exporters for these + ciphersuites don't work -- which caused relays to fail to handshake + with one another when these ciphersuites were enabled. + Fixes bug 29241; bugfix on 0.3.5.1-alpha. diff --git a/src/lib/tls/tortls_nss.c b/src/lib/tls/tortls_nss.c index 00c4af0e97..3c62e98df1 100644 --- a/src/lib/tls/tortls_nss.c +++ b/src/lib/tls/tortls_nss.c @@ -152,6 +152,32 @@ we_like_auth_type(SSLAuthType at) } } +/** + * Return true iff this ciphersuite will be hit by a mozilla bug 1312976, + * which makes TLS key exporters not work with TLS 1.2 non-SHA256 + * ciphersuites. + **/ +static bool +ciphersuite_has_nss_export_bug(const SSLCipherSuiteInfo *info) +{ + /* For more information on the bug, see + https://bugzilla.mozilla.org/show_bug.cgi?id=1312976 */ + + /* This bug only exists in TLS 1.2. */ + if (info->authType == ssl_auth_tls13_any) + return false; + + /* Sadly, there's no way to get this information from the + * CipherSuiteInfo object itself other than by looking at the + * name. */ + if (strstr(info->cipherSuiteName, "_SHA384") || + strstr(info->cipherSuiteName, "_SHA512")) { + return true; + } + + return false; +} + tor_tls_context_t * tor_tls_context_new(crypto_pk_t *identity, unsigned int key_lifetime, unsigned flags, int is_client) @@ -256,6 +282,12 @@ tor_tls_context_new(crypto_pk_t *identity, !we_like_mac_algorithm(info.macAlgorithm) || !we_like_auth_type(info.authType)/* Requires NSS 3.24 */; + if (ciphersuite_has_nss_export_bug(&info)) { + /* SSL_ExportKeyingMaterial will fail; we can't use this cipher. + */ + disable = 1; + } + s = SSL_CipherPrefSet(ctx->ctx, ciphers[i], disable ? PR_FALSE : PR_TRUE); if (s != SECSuccess) @@ -726,10 +758,18 @@ tor_tls_export_key_material,(tor_tls_t *tls, uint8_t *secrets_out, tor_assert(context_len <= UINT_MAX); SECStatus s; + /* Make sure that the error code is set here, so that we can be sure that + * any error code set after a failure was in fact caused by + * SSL_ExportKeyingMaterial. */ + PR_SetError(PR_UNKNOWN_ERROR, 0); s = SSL_ExportKeyingMaterial(tls->ssl, label, (unsigned)strlen(label), PR_TRUE, context, (unsigned)context_len, secrets_out, DIGEST256_LEN); + if (s != SECSuccess) { + tls_log_errors(tls, LOG_WARN, LD_CRYPTO, + "exporting key material for a TLS handshake"); + } return (s == SECSuccess) ? 0 : -1; } |