Support for DH and ECDH key exchange for QSslSocket servers

Despite supporting DH and ECDH key exchange as a client, Qt did not provide
any default parameters which prevented them being used as a server. A
future change should allow the user to control the parameters used, but
these defaults should be okay for most users.

[ChangeLog][Important Behavior Changes] Support for DH and ECDH key exchange
cipher suites when acting as an SSL server has been made possible. This
change means the you can now implement servers that offer forward-secrecy
using Qt.

Task-number: QTBUG-20666
Change-Id: I469163900e4313da9d2d0c3e1e5e47ef46320b17
Reviewed-by: Daniel Molkentin <daniel@molkentin.de>
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>

3 files changed, 80 insertions, 0 deletions

diff --git a/src/network/ssl/qsslcontext.cpp b/src/network/ssl/qsslcontext.cpp
index 1634ba0649..9c68218062 100644
--- a/src/network/ssl/qsslcontext.cpp
+++ b/src/network/ssl/qsslcontext.cpp
@@ -55,6 +55,53 @@ QT_BEGIN_NAMESPACE
 extern int q_X509Callback(int ok, X509_STORE_CTX *ctx);
 extern QString getErrorsFromOpenSsl();
 
+// Default DH params
+// 1024-bit MODP Group with 160-bit Prime Order Subgroup
+// From RFC 5114
+static unsigned const char dh1024_p[]={
+    0xB1,0x0B,0x8F,0x96,0xA0,0x80,0xE0,0x1D,0xDE,0x92,0xDE,0x5E,
+    0xAE,0x5D,0x54,0xEC,0x52,0xC9,0x9F,0xBC,0xFB,0x06,0xA3,0xC6,
+    0x9A,0x6A,0x9D,0xCA,0x52,0xD2,0x3B,0x61,0x60,0x73,0xE2,0x86,
+    0x75,0xA2,0x3D,0x18,0x98,0x38,0xEF,0x1E,0x2E,0xE6,0x52,0xC0,
+    0x13,0xEC,0xB4,0xAE,0xA9,0x06,0x11,0x23,0x24,0x97,0x5C,0x3C,
+    0xD4,0x9B,0x83,0xBF,0xAC,0xCB,0xDD,0x7D,0x90,0xC4,0xBD,0x70,
+    0x98,0x48,0x8E,0x9C,0x21,0x9A,0x73,0x72,0x4E,0xFF,0xD6,0xFA,
+    0xE5,0x64,0x47,0x38,0xFA,0xA3,0x1A,0x4F,0xF5,0x5B,0xCC,0xC0,
+    0xA1,0x51,0xAF,0x5F,0x0D,0xC8,0xB4,0xBD,0x45,0xBF,0x37,0xDF,
+    0x36,0x5C,0x1A,0x65,0xE6,0x8C,0xFD,0xA7,0x6D,0x4D,0xA7,0x08,
+    0xDF,0x1F,0xB2,0xBC,0x2E,0x4A,0x43,0x71
+};
+
+static unsigned const char dh1024_g[]={
+    0xA4,0xD1,0xCB,0xD5,0xC3,0xFD,0x34,0x12,0x67,0x65,0xA4,0x42,
+    0xEF,0xB9,0x99,0x05,0xF8,0x10,0x4D,0xD2,0x58,0xAC,0x50,0x7F,
+    0xD6,0x40,0x6C,0xFF,0x14,0x26,0x6D,0x31,0x26,0x6F,0xEA,0x1E,
+    0x5C,0x41,0x56,0x4B,0x77,0x7E,0x69,0x0F,0x55,0x04,0xF2,0x13,
+    0x16,0x02,0x17,0xB4,0xB0,0x1B,0x88,0x6A,0x5E,0x91,0x54,0x7F,
+    0x9E,0x27,0x49,0xF4,0xD7,0xFB,0xD7,0xD3,0xB9,0xA9,0x2E,0xE1,
+    0x90,0x9D,0x0D,0x22,0x63,0xF8,0x0A,0x76,0xA6,0xA2,0x4C,0x08,
+    0x7A,0x09,0x1F,0x53,0x1D,0xBF,0x0A,0x01,0x69,0xB6,0xA2,0x8A,
+    0xD6,0x62,0xA4,0xD1,0x8E,0x73,0xAF,0xA3,0x2D,0x77,0x9D,0x59,
+    0x18,0xD0,0x8B,0xC8,0x85,0x8F,0x4D,0xCE,0xF9,0x7C,0x2A,0x24,
+    0x85,0x5E,0x6E,0xEB,0x22,0xB3,0xB2,0xE5
+};
+
+static DH *get_dh1024()
+{
+    DH *dh = q_DH_new();
+    if (!dh)
+        return 0;
+
+    dh->p = q_BN_bin2bn(dh1024_p, sizeof(dh1024_p), 0);
+    dh->g = q_BN_bin2bn(dh1024_g, sizeof(dh1024_g), 0);
+    if (!dh->p || !dh->g) {
+        q_DH_free(dh);
+        return 0;
+    }
+
+    return dh;
+}
+
 QSslContext::QSslContext()
     : ctx(0),
     pkey(0),
@@ -261,6 +308,18 @@ init_context:
     if (!configuration.sessionTicket().isEmpty())
         sslContext->setSessionASN1(configuration.sessionTicket());
 
+    // Set temp DH params
+    DH *dh = 0;
+    dh = get_dh1024();
+    q_SSL_CTX_set_tmp_dh(sslContext->ctx, dh);
+    q_DH_free(dh);
+
+    // Set temp ECDH params
+    EC_KEY *ecdh = 0;
+    ecdh = q_EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+    q_SSL_CTX_set_tmp_ecdh(sslContext->ctx, ecdh);
+    q_EC_KEY_free(ecdh);
+
     return sslContext;
 }
 
diff --git a/src/network/ssl/qsslsocket_openssl_symbols.cpp b/src/network/ssl/qsslsocket_openssl_symbols.cpp
index 79bce22b0d..01c0f6f810 100644
--- a/src/network/ssl/qsslsocket_openssl_symbols.cpp
+++ b/src/network/ssl/qsslsocket_openssl_symbols.cpp
@@ -361,6 +361,11 @@ DEFINEFUNC3(void, SSL_CTX_set_next_proto_select_cb, SSL_CTX *s, s,
 DEFINEFUNC3(void, SSL_get0_next_proto_negotiated, const SSL *s, s,
             const unsigned char **data, data, unsigned *len, len, return, DUMMYARG)
 #endif // OPENSSL_VERSION_NUMBER >= 0x1000100fL ...
+DEFINEFUNC(DH *, DH_new, DUMMYARG, DUMMYARG, return 0, return)
+DEFINEFUNC(void, DH_free, DH *dh, dh, return, DUMMYARG)
+DEFINEFUNC3(BIGNUM *, BN_bin2bn, const unsigned char *s, s, int len, len, BIGNUM *ret, ret, return 0, return)
+DEFINEFUNC(EC_KEY *, EC_KEY_new_by_curve_name, int nid, nid, return 0, return)
+DEFINEFUNC(void, EC_KEY_free, EC_KEY *ecdh, ecdh, return, DUMMYARG)
 
 #define RESOLVEFUNC(func) \
     if (!(_q_##func = _q_PTR_##func(libs.first->resolve(#func)))     \
@@ -835,6 +840,11 @@ bool q_resolveOpenSslSymbols()
     RESOLVEFUNC(SSL_CTX_set_next_proto_select_cb)
     RESOLVEFUNC(SSL_get0_next_proto_negotiated)
 #endif // OPENSSL_VERSION_NUMBER >= 0x1000100fL ...
+    RESOLVEFUNC(DH_new)
+    RESOLVEFUNC(DH_free)
+    RESOLVEFUNC(BN_bin2bn)
+    RESOLVEFUNC(EC_KEY_new_by_curve_name)
+    RESOLVEFUNC(EC_KEY_free)
 
     symbolsResolved = true;
     delete libs.first;
diff --git a/src/network/ssl/qsslsocket_openssl_symbols_p.h b/src/network/ssl/qsslsocket_openssl_symbols_p.h
index 500fe9493b..1e68fdd6c2 100644
--- a/src/network/ssl/qsslsocket_openssl_symbols_p.h
+++ b/src/network/ssl/qsslsocket_openssl_symbols_p.h
@@ -427,6 +427,17 @@ int q_X509_STORE_CTX_get_error_depth(X509_STORE_CTX *ctx);
 X509 *q_X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx);
 STACK_OF(X509) *q_X509_STORE_CTX_get_chain(X509_STORE_CTX *ctx);
 
+// Diffie-Hellman support
+DH *q_DH_new();
+void q_DH_free(DH *dh);
+BIGNUM *q_BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
+#define q_SSL_CTX_set_tmp_dh(ctx, dh) q_SSL_CTX_ctrl((ctx), SSL_CTRL_SET_TMP_DH, 0, (char *)dh)
+
+// EC Diffie-Hellman support
+EC_KEY *q_EC_KEY_new_by_curve_name(int nid);
+void q_EC_KEY_free(EC_KEY *ecdh);
+#define q_SSL_CTX_set_tmp_ecdh(ctx, ecdh) q_SSL_CTX_ctrl((ctx), SSL_CTRL_SET_TMP_ECDH, 0, (char *)ecdh)
+
 #define q_BIO_get_mem_data(b, pp) (int)q_BIO_ctrl(b,BIO_CTRL_INFO,0,(char *)pp)
 #define q_BIO_pending(b) (int)q_BIO_ctrl(b,BIO_CTRL_PENDING,0,NULL)
 #ifdef SSLEAY_MACROS