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xemu/crypto/secret.c
Markus Armbruster d2623129a7 qom: Drop parameter @errp of object_property_add() & friends 
The only way object_property_add() can fail is when a property with
the same name already exists.  Since our property names are all
hardcoded, failure is a programming error, and the appropriate way to
handle it is passing &error_abort.

Same for its variants, except for object_property_add_child(), which
additionally fails when the child already has a parent.  Parentage is
also under program control, so this is a programming error, too.

We have a bit over 500 callers.  Almost half of them pass
&error_abort, slightly fewer ignore errors, one test case handles
errors, and the remaining few callers pass them to their own callers.

The previous few commits demonstrated once again that ignoring
programming errors is a bad idea.

Of the few ones that pass on errors, several violate the Error API.
The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.  ich9_pm_add_properties(), sparc32_ledma_realize(),
sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize()
are wrong that way.

When the one appropriate choice of argument is &error_abort, letting
users pick the argument is a bad idea.

Drop parameter @errp and assert the preconditions instead.

There's one exception to "duplicate property name is a programming
error": the way object_property_add() implements the magic (and
undocumented) "automatic arrayification".  Don't drop @errp there.
Instead, rename object_property_add() to object_property_try_add(),
and add the obvious wrapper object_property_add().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-15-armbru@redhat.com>
[Two semantic rebase conflicts resolved]
2020-05-15 07:07:58 +02:00

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/*
* QEMU crypto secret support
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include "crypto/secret.h"
#include "crypto/cipher.h"
#include "qapi/error.h"
#include "qom/object_interfaces.h"
#include "qemu/base64.h"
#include "qemu/module.h"
#include "trace.h"
static void
qcrypto_secret_load_data(QCryptoSecret *secret,
uint8_t **output,
size_t *outputlen,
Error **errp)
{
char *data = NULL;
size_t length = 0;
GError *gerr = NULL;
*output = NULL;
*outputlen = 0;
if (secret->file) {
if (secret->data) {
error_setg(errp,
"'file' and 'data' are mutually exclusive");
return;
}
if (!g_file_get_contents(secret->file, &data, &length, &gerr)) {
error_setg(errp,
"Unable to read %s: %s",
secret->file, gerr->message);
g_error_free(gerr);
return;
}
*output = (uint8_t *)data;
*outputlen = length;
} else if (secret->data) {
*outputlen = strlen(secret->data);
*output = (uint8_t *)g_strdup(secret->data);
} else {
error_setg(errp, "Either 'file' or 'data' must be provided");
}
}
static void qcrypto_secret_decrypt(QCryptoSecret *secret,
const uint8_t *input,
size_t inputlen,
uint8_t **output,
size_t *outputlen,
Error **errp)
{
g_autofree uint8_t *key = NULL;
g_autofree uint8_t *ciphertext = NULL;
g_autofree uint8_t *iv = NULL;
size_t keylen, ciphertextlen, ivlen;
g_autoptr(QCryptoCipher) aes = NULL;
g_autofree uint8_t *plaintext = NULL;
*output = NULL;
*outputlen = 0;
if (qcrypto_secret_lookup(secret->keyid,
&key, &keylen,
errp) < 0) {
return;
}
if (keylen != 32) {
error_setg(errp, "Key should be 32 bytes in length");
return;
}
if (!secret->iv) {
error_setg(errp, "IV is required to decrypt secret");
return;
}
iv = qbase64_decode(secret->iv, -1, &ivlen, errp);
if (!iv) {
return;
}
if (ivlen != 16) {
error_setg(errp, "IV should be 16 bytes in length not %zu",
ivlen);
return;
}
aes = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_256,
QCRYPTO_CIPHER_MODE_CBC,
key, keylen,
errp);
if (!aes) {
return;
}
if (qcrypto_cipher_setiv(aes, iv, ivlen, errp) < 0) {
return;
}
if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
ciphertext = qbase64_decode((const gchar*)input,
inputlen,
&ciphertextlen,
errp);
if (!ciphertext) {
return;
}
plaintext = g_new0(uint8_t, ciphertextlen + 1);
} else {
ciphertextlen = inputlen;
plaintext = g_new0(uint8_t, inputlen + 1);
}
if (qcrypto_cipher_decrypt(aes,
ciphertext ? ciphertext : input,
plaintext,
ciphertextlen,
errp) < 0) {
return;
}
if (plaintext[ciphertextlen - 1] > 16 ||
plaintext[ciphertextlen - 1] > ciphertextlen) {
error_setg(errp, "Incorrect number of padding bytes (%d) "
"found on decrypted data",
(int)plaintext[ciphertextlen - 1]);
return;
}
/* Even though plaintext may contain arbitrary NUL
* ensure it is explicitly NUL terminated.
*/
ciphertextlen -= plaintext[ciphertextlen - 1];
plaintext[ciphertextlen] = '\0';
*output = g_steal_pointer(&plaintext);
*outputlen = ciphertextlen;
}
static void qcrypto_secret_decode(const uint8_t *input,
size_t inputlen,
uint8_t **output,
size_t *outputlen,
Error **errp)
{
*output = qbase64_decode((const gchar*)input,
inputlen,
outputlen,
errp);
}
static void
qcrypto_secret_prop_set_loaded(Object *obj,
bool value,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
if (value) {
Error *local_err = NULL;
uint8_t *input = NULL;
size_t inputlen = 0;
uint8_t *output = NULL;
size_t outputlen = 0;
qcrypto_secret_load_data(secret, &input, &inputlen, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
if (secret->keyid) {
qcrypto_secret_decrypt(secret, input, inputlen,
&output, &outputlen, &local_err);
g_free(input);
if (local_err) {
error_propagate(errp, local_err);
return;
}
input = output;
inputlen = outputlen;
} else {
if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
qcrypto_secret_decode(input, inputlen,
&output, &outputlen, &local_err);
g_free(input);
if (local_err) {
error_propagate(errp, local_err);
return;
}
input = output;
inputlen = outputlen;
}
}
secret->rawdata = input;
secret->rawlen = inputlen;
} else {
g_free(secret->rawdata);
secret->rawdata = NULL;
secret->rawlen = 0;
}
}
static bool
qcrypto_secret_prop_get_loaded(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
return secret->rawdata != NULL;
}
static void
qcrypto_secret_prop_set_format(Object *obj,
int value,
Error **errp G_GNUC_UNUSED)
{
QCryptoSecret *creds = QCRYPTO_SECRET(obj);
creds->format = value;
}
static int
qcrypto_secret_prop_get_format(Object *obj,
Error **errp G_GNUC_UNUSED)
{
QCryptoSecret *creds = QCRYPTO_SECRET(obj);
return creds->format;
}
static void
qcrypto_secret_prop_set_data(Object *obj,
const char *value,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
g_free(secret->data);
secret->data = g_strdup(value);
}
static char *
qcrypto_secret_prop_get_data(Object *obj,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
return g_strdup(secret->data);
}
static void
qcrypto_secret_prop_set_file(Object *obj,
const char *value,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
g_free(secret->file);
secret->file = g_strdup(value);
}
static char *
qcrypto_secret_prop_get_file(Object *obj,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
return g_strdup(secret->file);
}
static void
qcrypto_secret_prop_set_iv(Object *obj,
const char *value,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
g_free(secret->iv);
secret->iv = g_strdup(value);
}
static char *
qcrypto_secret_prop_get_iv(Object *obj,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
return g_strdup(secret->iv);
}
static void
qcrypto_secret_prop_set_keyid(Object *obj,
const char *value,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
g_free(secret->keyid);
secret->keyid = g_strdup(value);
}
static char *
qcrypto_secret_prop_get_keyid(Object *obj,
Error **errp)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
return g_strdup(secret->keyid);
}
static void
qcrypto_secret_complete(UserCreatable *uc, Error **errp)
{
object_property_set_bool(OBJECT(uc), true, "loaded", errp);
}
static void
qcrypto_secret_finalize(Object *obj)
{
QCryptoSecret *secret = QCRYPTO_SECRET(obj);
g_free(secret->iv);
g_free(secret->file);
g_free(secret->keyid);
g_free(secret->rawdata);
g_free(secret->data);
}
static void
qcrypto_secret_class_init(ObjectClass *oc, void *data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
ucc->complete = qcrypto_secret_complete;
object_class_property_add_bool(oc, "loaded",
qcrypto_secret_prop_get_loaded,
qcrypto_secret_prop_set_loaded);
object_class_property_add_enum(oc, "format",
"QCryptoSecretFormat",
&QCryptoSecretFormat_lookup,
qcrypto_secret_prop_get_format,
qcrypto_secret_prop_set_format);
object_class_property_add_str(oc, "data",
qcrypto_secret_prop_get_data,
qcrypto_secret_prop_set_data);
object_class_property_add_str(oc, "file",
qcrypto_secret_prop_get_file,
qcrypto_secret_prop_set_file);
object_class_property_add_str(oc, "keyid",
qcrypto_secret_prop_get_keyid,
qcrypto_secret_prop_set_keyid);
object_class_property_add_str(oc, "iv",
qcrypto_secret_prop_get_iv,
qcrypto_secret_prop_set_iv);
}
int qcrypto_secret_lookup(const char *secretid,
uint8_t **data,
size_t *datalen,
Error **errp)
{
Object *obj;
QCryptoSecret *secret;
obj = object_resolve_path_component(
object_get_objects_root(), secretid);
if (!obj) {
error_setg(errp, "No secret with id '%s'", secretid);
return -1;
}
secret = (QCryptoSecret *)
object_dynamic_cast(obj,
TYPE_QCRYPTO_SECRET);
if (!secret) {
error_setg(errp, "Object with id '%s' is not a secret",
secretid);
return -1;
}
if (!secret->rawdata) {
error_setg(errp, "Secret with id '%s' has no data",
secretid);
return -1;
}
*data = g_new0(uint8_t, secret->rawlen + 1);
memcpy(*data, secret->rawdata, secret->rawlen);
(*data)[secret->rawlen] = '\0';
*datalen = secret->rawlen;
return 0;
}
char *qcrypto_secret_lookup_as_utf8(const char *secretid,
Error **errp)
{
uint8_t *data;
size_t datalen;
if (qcrypto_secret_lookup(secretid,
&data,
&datalen,
errp) < 0) {
return NULL;
}
if (!g_utf8_validate((const gchar*)data, datalen, NULL)) {
error_setg(errp,
"Data from secret %s is not valid UTF-8",
secretid);
g_free(data);
return NULL;
}
return (char *)data;
}
char *qcrypto_secret_lookup_as_base64(const char *secretid,
Error **errp)
{
uint8_t *data;
size_t datalen;
char *ret;
if (qcrypto_secret_lookup(secretid,
&data,
&datalen,
errp) < 0) {
return NULL;
}
ret = g_base64_encode(data, datalen);
g_free(data);
return ret;
}
static const TypeInfo qcrypto_secret_info = {
.parent = TYPE_OBJECT,
.name = TYPE_QCRYPTO_SECRET,
.instance_size = sizeof(QCryptoSecret),
.instance_finalize = qcrypto_secret_finalize,
.class_size = sizeof(QCryptoSecretClass),
.class_init = qcrypto_secret_class_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ }
}
};
static void
qcrypto_secret_register_types(void)
{
type_register_static(&qcrypto_secret_info);
}
type_init(qcrypto_secret_register_types);
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