[PULL 5/5] crypto/tls-cipher-suites: Produce fw_cfg consumable blob

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Since our format is consumable by the fw_cfg device,
we can implement the FW_CFG_DATA_GENERATOR interface.

Example of use to dump the cipher suites (if tracing enabled):

  $ qemu-system-x86_64 -S \
    -object tls-cipher-suites,id=mysuite1,priority=@SYSTEM \
    -fw_cfg name=etc/path/to/ciphers,gen_id=mysuite1 \
    -trace qcrypto\*
  1590664444.197123:qcrypto_tls_cipher_suite_priority priority: @SYSTEM
  1590664444.197219:qcrypto_tls_cipher_suite_info data=[0x13,0x02] version=TLS1.3 name=TLS_AES_256_GCM_SHA384
  1590664444.197228:qcrypto_tls_cipher_suite_info data=[0x13,0x03] version=TLS1.3 name=TLS_CHACHA20_POLY1305_SHA256
  1590664444.197233:qcrypto_tls_cipher_suite_info data=[0x13,0x01] version=TLS1.3 name=TLS_AES_128_GCM_SHA256
  1590664444.197236:qcrypto_tls_cipher_suite_info data=[0x13,0x04] version=TLS1.3 name=TLS_AES_128_CCM_SHA256
  1590664444.197240:qcrypto_tls_cipher_suite_info data=[0xc0,0x30] version=TLS1.2 name=TLS_ECDHE_RSA_AES_256_GCM_SHA384
  1590664444.197245:qcrypto_tls_cipher_suite_info data=[0xcc,0xa8] version=TLS1.2 name=TLS_ECDHE_RSA_CHACHA20_POLY1305
  1590664444.197250:qcrypto_tls_cipher_suite_info data=[0xc0,0x14] version=TLS1.0 name=TLS_ECDHE_RSA_AES_256_CBC_SHA1
  1590664444.197254:qcrypto_tls_cipher_suite_info data=[0xc0,0x2f] version=TLS1.2 name=TLS_ECDHE_RSA_AES_128_GCM_SHA256
  1590664444.197258:qcrypto_tls_cipher_suite_info data=[0xc0,0x13] version=TLS1.0 name=TLS_ECDHE_RSA_AES_128_CBC_SHA1
  1590664444.197261:qcrypto_tls_cipher_suite_info data=[0xc0,0x2c] version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_256_GCM_SHA384
  1590664444.197266:qcrypto_tls_cipher_suite_info data=[0xcc,0xa9] version=TLS1.2 name=TLS_ECDHE_ECDSA_CHACHA20_POLY1305
  1590664444.197270:qcrypto_tls_cipher_suite_info data=[0xc0,0xad] version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_256_CCM
  1590664444.197274:qcrypto_tls_cipher_suite_info data=[0xc0,0x0a] version=TLS1.0 name=TLS_ECDHE_ECDSA_AES_256_CBC_SHA1
  1590664444.197278:qcrypto_tls_cipher_suite_info data=[0xc0,0x2b] version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_128_GCM_SHA256
  1590664444.197283:qcrypto_tls_cipher_suite_info data=[0xc0,0xac] version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_128_CCM
  1590664444.197287:qcrypto_tls_cipher_suite_info data=[0xc0,0x09] version=TLS1.0 name=TLS_ECDHE_ECDSA_AES_128_CBC_SHA1
  1590664444.197291:qcrypto_tls_cipher_suite_info data=[0x00,0x9d] version=TLS1.2 name=TLS_RSA_AES_256_GCM_SHA384
  1590664444.197296:qcrypto_tls_cipher_suite_info data=[0xc0,0x9d] version=TLS1.2 name=TLS_RSA_AES_256_CCM
  1590664444.197300:qcrypto_tls_cipher_suite_info data=[0x00,0x35] version=TLS1.0 name=TLS_RSA_AES_256_CBC_SHA1
  1590664444.197304:qcrypto_tls_cipher_suite_info data=[0x00,0x9c] version=TLS1.2 name=TLS_RSA_AES_128_GCM_SHA256
  1590664444.197308:qcrypto_tls_cipher_suite_info data=[0xc0,0x9c] version=TLS1.2 name=TLS_RSA_AES_128_CCM
  1590664444.197312:qcrypto_tls_cipher_suite_info data=[0x00,0x2f] version=TLS1.0 name=TLS_RSA_AES_128_CBC_SHA1
  1590664444.197316:qcrypto_tls_cipher_suite_info data=[0x00,0x9f] version=TLS1.2 name=TLS_DHE_RSA_AES_256_GCM_SHA384
  1590664444.197320:qcrypto_tls_cipher_suite_info data=[0xcc,0xaa] version=TLS1.2 name=TLS_DHE_RSA_CHACHA20_POLY1305
  1590664444.197325:qcrypto_tls_cipher_suite_info data=[0xc0,0x9f] version=TLS1.2 name=TLS_DHE_RSA_AES_256_CCM
  1590664444.197329:qcrypto_tls_cipher_suite_info data=[0x00,0x39] version=TLS1.0 name=TLS_DHE_RSA_AES_256_CBC_SHA1
  1590664444.197333:qcrypto_tls_cipher_suite_info data=[0x00,0x9e] version=TLS1.2 name=TLS_DHE_RSA_AES_128_GCM_SHA256
  1590664444.197337:qcrypto_tls_cipher_suite_info data=[0xc0,0x9e] version=TLS1.2 name=TLS_DHE_RSA_AES_128_CCM
  1590664444.197341:qcrypto_tls_cipher_suite_info data=[0x00,0x33] version=TLS1.0 name=TLS_DHE_RSA_AES_128_CBC_SHA1
  1590664444.197345:qcrypto_tls_cipher_suite_count count: 29

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200623172726.21040-6-philmd@redhat.com>
---
 crypto/tls-cipher-suites.c | 11 +++++++++++
 qemu-options.hx            | 18 ++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/crypto/tls-cipher-suites.c b/crypto/tls-cipher-suites.c
index a4e0f84307..0d305b684b 100644
--- a/crypto/tls-cipher-suites.c
+++ b/crypto/tls-cipher-suites.c
@@ -13,6 +13,7 @@
 #include "qom/object_interfaces.h"
 #include "crypto/tlscreds.h"
 #include "crypto/tls-cipher-suites.h"
+#include "hw/nvram/fw_cfg.h"
 #include "trace.h"
 
 /*
@@ -88,11 +89,20 @@ static void qcrypto_tls_cipher_suites_complete(UserCreatable *uc,
     }
 }
 
+static GByteArray *qcrypto_tls_cipher_suites_fw_cfg_gen_data(Object *obj,
+                                                             Error **errp)
+{
+    return qcrypto_tls_cipher_suites_get_data(QCRYPTO_TLS_CIPHER_SUITES(obj),
+                                              errp);
+}
+
 static void qcrypto_tls_cipher_suites_class_init(ObjectClass *oc, void *data)
 {
     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
+    FWCfgDataGeneratorClass *fwgc = FW_CFG_DATA_GENERATOR_CLASS(oc);
 
     ucc->complete = qcrypto_tls_cipher_suites_complete;
+    fwgc->get_data = qcrypto_tls_cipher_suites_fw_cfg_gen_data;
 }
 
 static const TypeInfo qcrypto_tls_cipher_suites_info = {
@@ -103,6 +113,7 @@ static const TypeInfo qcrypto_tls_cipher_suites_info = {
     .class_init = qcrypto_tls_cipher_suites_class_init,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_USER_CREATABLE },
+        { TYPE_FW_CFG_DATA_GENERATOR_INTERFACE },
         { }
     }
 };
diff --git a/qemu-options.hx b/qemu-options.hx
index ecc4658e1f..b2cbbbf281 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4586,6 +4586,24 @@ SRST
         string as described at
         https://gnutls.org/manual/html_node/Priority-Strings.html.
 
+        An example of use of this object is to control UEFI HTTPS Boot.
+        The tls-cipher-suites object exposes the ordered list of permitted
+        TLS cipher suites from the host side to the guest firmware, via
+        fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
+        objects. The firmware uses the IANA_TLS_CIPHER array for configuring
+        guest-side TLS.
+
+        In the following example, the priority at which the host-side policy
+        is retrieved is given by the ``priority`` property.
+        Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
+        refer to /etc/crypto-policies/back-ends/gnutls.config.
+
+        .. parsed-literal::
+
+             # |qemu_system| \
+                 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \
+                 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
+
     ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
         Interval t can't be 0, this filter batches the packet delivery:
         all packets arriving in a given interval on netdev netdevid are
-- 
2.21.3