firmware (and crypto) patches

- add the tls-cipher-suites object,
 - add the ability to QOM objects to produce data consumable
   by the fw_cfg device,
 - let the tls-cipher-suites object implement the
   FW_CFG_DATA_GENERATOR interface.
 
 This is required by EDK2 'HTTPS Boot' feature of OVMF to tell
 the guest which TLS ciphers it can use.
 
 CI jobs results:
   https://travis-ci.org/github/philmd/qemu/builds/704724619
   https://gitlab.com/philmd/qemu/-/pipelines/162938106
   https://cirrus-ci.com/build/4682977303068672
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Merge remote-tracking branch 'remotes/philmd-gitlab/tags/fw_cfg-20200704' into staging

firmware (and crypto) patches

- add the tls-cipher-suites object,
- add the ability to QOM objects to produce data consumable
  by the fw_cfg device,
- let the tls-cipher-suites object implement the
  FW_CFG_DATA_GENERATOR interface.

This is required by EDK2 'HTTPS Boot' feature of OVMF to tell
the guest which TLS ciphers it can use.

CI jobs results:
  https://travis-ci.org/github/philmd/qemu/builds/704724619
  https://gitlab.com/philmd/qemu/-/pipelines/162938106
  https://cirrus-ci.com/build/4682977303068672

# gpg: Signature made Sat 04 Jul 2020 17:37:08 BST
# gpg:                using RSA key FAABE75E12917221DCFD6BB2E3E32C2CDEADC0DE
# gpg: Good signature from "Philippe Mathieu-Daudé (F4BUG) <f4bug@amsat.org>" [full]
# Primary key fingerprint: FAAB E75E 1291 7221 DCFD  6BB2 E3E3 2C2C DEAD C0DE

* remotes/philmd-gitlab/tags/fw_cfg-20200704:
  crypto/tls-cipher-suites: Produce fw_cfg consumable blob
  softmmu/vl: Allow -fw_cfg 'gen_id' option to use the 'etc/' namespace
  softmmu/vl: Let -fw_cfg option take a 'gen_id' argument
  hw/nvram/fw_cfg: Add the FW_CFG_DATA_GENERATOR interface
  crypto: Add tls-cipher-suites object

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

crypto/Makefile.objs

@@ -13,6 +13,7 @@ crypto-obj-y += cipher.o
 crypto-obj-$(CONFIG_AF_ALG) += afalg.o
 crypto-obj-$(CONFIG_AF_ALG) += cipher-afalg.o
 crypto-obj-$(CONFIG_AF_ALG) += hash-afalg.o
+crypto-obj-$(CONFIG_GNUTLS) += tls-cipher-suites.o
 crypto-obj-y += tlscreds.o
 crypto-obj-y += tlscredsanon.o
 crypto-obj-y += tlscredspsk.o

crypto/tls-cipher-suites.c

@@ -0,0 +1,126 @@
+/*
+ * QEMU TLS Cipher Suites
+ *
+ * Copyright (c) 2018-2020 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <philmd@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "crypto/tlscreds.h"
+#include "crypto/tls-cipher-suites.h"
+#include "hw/nvram/fw_cfg.h"
+#include "trace.h"
+
+/*
+ * IANA registered TLS ciphers:
+ * https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-4
+ */
+typedef struct {
+    uint8_t data[2];
+} QEMU_PACKED IANA_TLS_CIPHER;
+
+GByteArray *qcrypto_tls_cipher_suites_get_data(QCryptoTLSCipherSuites *obj,
+                                               Error **errp)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
+    gnutls_priority_t pcache;
+    GByteArray *byte_array;
+    const char *err;
+    size_t i;
+    int ret;
+
+    trace_qcrypto_tls_cipher_suite_priority(creds->priority);
+    ret = gnutls_priority_init(&pcache, creds->priority, &err);
+    if (ret < 0) {
+        error_setg(errp, "Syntax error using priority '%s': %s",
+                   creds->priority, gnutls_strerror(ret));
+        return NULL;
+    }
+
+    byte_array = g_byte_array_new();
+
+    for (i = 0;; i++) {
+        int ret;
+        unsigned idx;
+        const char *name;
+        IANA_TLS_CIPHER cipher;
+        gnutls_protocol_t protocol;
+        const char *version;
+
+        ret = gnutls_priority_get_cipher_suite_index(pcache, i, &idx);
+        if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
+            break;
+        }
+        if (ret == GNUTLS_E_UNKNOWN_CIPHER_SUITE) {
+            continue;
+        }
+
+        name = gnutls_cipher_suite_info(idx, (unsigned char *)&cipher,
+                                        NULL, NULL, NULL, &protocol);
+        if (name == NULL) {
+            continue;
+        }
+
+        version = gnutls_protocol_get_name(protocol);
+        g_byte_array_append(byte_array, cipher.data, 2);
+        trace_qcrypto_tls_cipher_suite_info(cipher.data[0],
+                                            cipher.data[1],
+                                            version, name);
+    }
+    trace_qcrypto_tls_cipher_suite_count(byte_array->len);
+    gnutls_priority_deinit(pcache);
+
+    return byte_array;
+}
+
+static void qcrypto_tls_cipher_suites_complete(UserCreatable *uc,
+                                               Error **errp)
+{
+    QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(uc);
+
+    if (!creds->priority) {
+        error_setg(errp, "'priority' property is not set");
+        return;
+    }
+}
+
+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 = {
+    .parent = TYPE_QCRYPTO_TLS_CREDS,
+    .name = TYPE_QCRYPTO_TLS_CIPHER_SUITES,
+    .instance_size = sizeof(QCryptoTLSCreds),
+    .class_size = sizeof(QCryptoTLSCredsClass),
+    .class_init = qcrypto_tls_cipher_suites_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { TYPE_FW_CFG_DATA_GENERATOR_INTERFACE },
+        { }
+    }
+};
+
+static void qcrypto_tls_cipher_suites_register_types(void)
+{
+    type_register_static(&qcrypto_tls_cipher_suites_info);
+}
+
+type_init(qcrypto_tls_cipher_suites_register_types);

crypto/trace-events

@@ -21,3 +21,8 @@ qcrypto_tls_creds_x509_load_cert_list(void *creds, const char *file) "TLS creds
 # tlssession.c
 qcrypto_tls_session_new(void *session, void *creds, const char *hostname, const char *authzid, int endpoint) "TLS session new session=%p creds=%p hostname=%s authzid=%s endpoint=%d"
 qcrypto_tls_session_check_creds(void *session, const char *status) "TLS session check creds session=%p status=%s"
+
+# tls-cipher-suites.c
+qcrypto_tls_cipher_suite_priority(const char *name) "priority: %s"
+qcrypto_tls_cipher_suite_info(uint8_t data0, uint8_t data1, const char *version, const char *name) "data=[0x%02x,0x%02x] version=%s name=%s"
+qcrypto_tls_cipher_suite_count(unsigned count) "count: %u"

docs/specs/fw_cfg.txt

@@ -219,7 +219,7 @@ To check the result, read the "control" field:
 
 = Externally Provided Items =
 
-As of v2.4, "file" fw_cfg items (i.e., items with selector keys above
+Since v2.4, "file" fw_cfg items (i.e., items with selector keys above
 FW_CFG_FILE_FIRST, and with a corresponding entry in the fw_cfg file
 directory structure) may be inserted via the QEMU command line, using
 the following syntax:
@@ -230,6 +230,13 @@ Or
 
     -fw_cfg [name=]<item_name>,string=<string>
 
+Since v5.1, QEMU allows some objects to generate fw_cfg-specific content,
+the content is then associated with a "file" item using the 'gen_id' option
+in the command line, using the following syntax:
+
+    -object <generator-type>,id=<generated_id>,[generator-specific-options] \
+    -fw_cfg [name=]<item_name>,gen_id=<generated_id>
+
 See QEMU man page for more documentation.
 
 Using item_name with plain ASCII characters only is recommended.
@@ -251,4 +258,8 @@ Prefix "opt/org.qemu/" is reserved for QEMU itself.
 Use of names not beginning with "opt/" is potentially dangerous and
 entirely unsupported.  QEMU will warn if you try.
 
+Use of names not beginning with "opt/" is tolerated with 'gen_id' (that
+is, the warning is suppressed), but you must know exactly what you're
+doing.
+
 All externally provided fw_cfg items are read-only to the guest.

hw/nvram/fw_cfg.c

@@ -1032,6 +1032,35 @@ void *fw_cfg_modify_file(FWCfgState *s, const char *filename,
     return NULL;
 }
 
+void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+                               const char *gen_id, Error **errp)
+{
+    FWCfgDataGeneratorClass *klass;
+    Error *local_err = NULL;
+    GByteArray *array;
+    Object *obj;
+    gsize size;
+
+    obj = object_resolve_path_component(object_get_objects_root(), gen_id);
+    if (!obj) {
+        error_setg(errp, "Cannot find object ID '%s'", gen_id);
+        return;
+    }
+    if (!object_dynamic_cast(obj, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)) {
+        error_setg(errp, "Object ID '%s' is not a '%s' subclass",
+                   gen_id, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE);
+        return;
+    }
+    klass = FW_CFG_DATA_GENERATOR_GET_CLASS(obj);
+    array = klass->get_data(obj, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+    size = array->len;
+    fw_cfg_add_file(s, filename, g_byte_array_free(array, TRUE), size);
+}
+
 static void fw_cfg_machine_reset(void *opaque)
 {
     MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
@@ -1333,12 +1362,18 @@ static const TypeInfo fw_cfg_mem_info = {
     .class_init    = fw_cfg_mem_class_init,
 };
 
+static const TypeInfo fw_cfg_data_generator_interface_info = {
+    .parent = TYPE_INTERFACE,
+    .name = TYPE_FW_CFG_DATA_GENERATOR_INTERFACE,
+    .class_size = sizeof(FWCfgDataGeneratorClass),
+};
 
 static void fw_cfg_register_types(void)
 {
     type_register_static(&fw_cfg_info);
     type_register_static(&fw_cfg_io_info);
     type_register_static(&fw_cfg_mem_info);
+    type_register_static(&fw_cfg_data_generator_interface_info);
 }
 
 type_init(fw_cfg_register_types)

include/crypto/tls-cipher-suites.h

@@ -0,0 +1,39 @@
+/*
+ * QEMU TLS Cipher Suites Registry (RFC8447)
+ *
+ * Copyright (c) 2018-2020 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <philmd@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef QCRYPTO_TLSCIPHERSUITES_H
+#define QCRYPTO_TLSCIPHERSUITES_H
+
+#include "qom/object.h"
+#include "crypto/tlscreds.h"
+
+#define TYPE_QCRYPTO_TLS_CIPHER_SUITES "tls-cipher-suites"
+#define QCRYPTO_TLS_CIPHER_SUITES(obj) \
+    OBJECT_CHECK(QCryptoTLSCipherSuites, (obj), TYPE_QCRYPTO_TLS_CIPHER_SUITES)
+
+typedef struct QCryptoTLSCipherSuites {
+    /* <private> */
+    QCryptoTLSCreds parent_obj;
+    /* <public> */
+} QCryptoTLSCipherSuites;
+
+/**
+  * qcrypto_tls_cipher_suites_get_data:
+  * @obj: pointer to a TLS cipher suites object
+  * @errp: pointer to a NULL-initialized error object
+  *
+  * Returns: reference to a byte array containing the data.
+  * The caller should release the reference when no longer
+  * required.
+  */
+GByteArray *qcrypto_tls_cipher_suites_get_data(QCryptoTLSCipherSuites *obj,
+                                               Error **errp);
+
+#endif /* QCRYPTO_TLSCIPHERSUITES_H */

include/hw/nvram/fw_cfg.h

@@ -9,11 +9,36 @@
 #define TYPE_FW_CFG     "fw_cfg"
 #define TYPE_FW_CFG_IO  "fw_cfg_io"
 #define TYPE_FW_CFG_MEM "fw_cfg_mem"
+#define TYPE_FW_CFG_DATA_GENERATOR_INTERFACE "fw_cfg-data-generator"
 
 #define FW_CFG(obj)     OBJECT_CHECK(FWCfgState,    (obj), TYPE_FW_CFG)
 #define FW_CFG_IO(obj)  OBJECT_CHECK(FWCfgIoState,  (obj), TYPE_FW_CFG_IO)
 #define FW_CFG_MEM(obj) OBJECT_CHECK(FWCfgMemState, (obj), TYPE_FW_CFG_MEM)
 
+#define FW_CFG_DATA_GENERATOR_CLASS(class) \
+    OBJECT_CLASS_CHECK(FWCfgDataGeneratorClass, (class), \
+                       TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+#define FW_CFG_DATA_GENERATOR_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(FWCfgDataGeneratorClass, (obj), \
+                     TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+
+typedef struct FWCfgDataGeneratorClass {
+    /*< private >*/
+    InterfaceClass parent_class;
+    /*< public >*/
+
+    /**
+     * get_data:
+     * @obj: the object implementing this interface
+     * @errp: pointer to a NULL-initialized error object
+     *
+     * Returns: reference to a byte array containing the data.
+     * The caller should release the reference when no longer
+     * required.
+     */
+    GByteArray *(*get_data)(Object *obj, Error **errp);
+} FWCfgDataGeneratorClass;
+
 typedef struct fw_cfg_file FWCfgFile;
 
 #define FW_CFG_ORDER_OVERRIDE_VGA    70
@@ -263,6 +288,24 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
 void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
                          size_t len);
 
+/**
+ * fw_cfg_add_from_generator:
+ * @s: fw_cfg device being modified
+ * @filename: name of new fw_cfg file item
+ * @gen_id: name of object implementing FW_CFG_DATA_GENERATOR interface
+ * @errp: pointer to a NULL initialized error object
+ *
+ * Add a new NAMED fw_cfg item with the content generated from the
+ * @gen_id object. The data generated by the @gen_id object is copied
+ * into the data structure of the fw_cfg device.
+ * The next available (unused) selector key starting at FW_CFG_FILE_FIRST
+ * will be used; also, a new entry will be added to the file directory
+ * structure residing at key value FW_CFG_FILE_DIR, containing the item name,
+ * data size, and assigned selector key value.
+ */
+void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+                               const char *gen_id, Error **errp);
+
 FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
                                 AddressSpace *dma_as);
 FWCfgState *fw_cfg_init_io(uint32_t iobase);

qemu-options.hx

@@ -4579,6 +4579,43 @@ SRST
         string as described at
         https://gnutls.org/manual/html_node/Priority-Strings.html.
 
+    ``-object tls-cipher-suites,id=id,priority=priority``
+        Creates a TLS cipher suites object, which can be used to control
+        the TLS cipher/protocol algorithms that applications are permitted
+        to use.
+
+        The ``id`` parameter is a unique ID which frontends will use to
+        access the ordered list of permitted TLS cipher suites from the
+        host.
+
+        The ``priority`` parameter allows to override the global default
+        priority used by gnutls. This can be useful if the system
+        administrator needs to use a weaker set of crypto priorities for
+        QEMU without potentially forcing the weakness onto all
+        applications. Or conversely if one wants wants a stronger
+        default for QEMU than for all other applications, they can do
+        this through this parameter. Its format is a gnutls priority
+        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

softmmu/vl.c

@@ -489,6 +489,11 @@ static QemuOptsList qemu_fw_cfg_opts = {
             .name = "string",
             .type = QEMU_OPT_STRING,
             .help = "Sets content of the blob to be inserted from a string",
+        }, {
+            .name = "gen_id",
+            .type = QEMU_OPT_STRING,
+            .help = "Sets id of the object generating the fw_cfg blob "
+                    "to be inserted",
         },
         { /* end of list */ }
     },
@@ -2020,7 +2025,7 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
 {
     gchar *buf;
     size_t size;
-    const char *name, *file, *str;
+    const char *name, *file, *str, *gen_id;
     FWCfgState *fw_cfg = (FWCfgState *) opaque;
 
     if (fw_cfg == NULL) {
@@ -2030,14 +2035,13 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
     name = qemu_opt_get(opts, "name");
     file = qemu_opt_get(opts, "file");
     str = qemu_opt_get(opts, "string");
+    gen_id = qemu_opt_get(opts, "gen_id");
 
-    /* we need name and either a file or the content string */
+    /* we need the name, and exactly one of: file, content string, gen_id */
-    if (!(nonempty_str(name) && (nonempty_str(file) || nonempty_str(str)))) {
+    if (!nonempty_str(name) ||
-        error_setg(errp, "invalid argument(s)");
+        nonempty_str(file) + nonempty_str(str) + nonempty_str(gen_id) != 1) {
-        return -1;
+        error_setg(errp, "name, plus exactly one of file,"
-    }
+                         " string and gen_id, are needed");
-    if (nonempty_str(file) && nonempty_str(str)) {
-        error_setg(errp, "file and string are mutually exclusive");
         return -1;
     }
     if (strlen(name) > FW_CFG_MAX_FILE_PATH - 1) {
@@ -2045,13 +2049,28 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
                    FW_CFG_MAX_FILE_PATH - 1);
         return -1;
     }
-    if (strncmp(name, "opt/", 4) != 0) {
+    if (nonempty_str(gen_id)) {
+        /*
+         * In this particular case where the content is populated
+         * internally, the "etc/" namespace protection is relaxed,
+         * so do not emit a warning.
+         */
+    } else if (strncmp(name, "opt/", 4) != 0) {
         warn_report("externally provided fw_cfg item names "
                     "should be prefixed with \"opt/\"");
     }
     if (nonempty_str(str)) {
         size = strlen(str); /* NUL terminator NOT included in fw_cfg blob */
         buf = g_memdup(str, size);
+    } else if (nonempty_str(gen_id)) {
+        Error *local_err = NULL;
+
+        fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return -1;
+        }
+        return 0;
     } else {
         GError *err = NULL;
         if (!g_file_get_contents(file, &buf, &size, &err)) {