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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "KeychainSecret.h"
#include <Security/Security.h>
#include "mozilla/Logging.h"
#include "mozilla/glean/SecurityManagerSslMetrics.h"
#include "nsPrintfCString.h"
// This is the implementation of KeychainSecret, an instantiation of OSKeyStore
// for OS X. It uses the system keychain, hence the name.
using namespace mozilla;
LazyLogModule gKeychainSecretLog("keychainsecret");
KeychainSecret::KeychainSecret() {}
KeychainSecret::~KeychainSecret() {}
ScopedCFType<CFStringRef> MozillaStringToCFString(const nsACString& stringIn) {
// https://developer.apple.com/documentation/corefoundation/1543419-cfstringcreatewithbytes
ScopedCFType<CFStringRef> stringOut(CFStringCreateWithBytes(
nullptr, reinterpret_cast<const UInt8*>(stringIn.BeginReading()),
stringIn.Length(), kCFStringEncodingUTF8, false));
return stringOut;
}
nsresult KeychainSecret::StoreSecret(const nsACString& aSecret,
const nsACString& aLabel) {
// This creates a CFDictionary of the form:
// { class: generic password,
// account: the given label,
// value: the given secret }
// "account" is the way we differentiate different secrets.
// By default, secrets stored by the application (Firefox) in this way are not
// accessible to other applications, so we shouldn't need to worry about
// unauthorized access or namespace collisions. This will be the case as long
// as we never set the kSecAttrAccessGroup attribute on the CFDictionary. The
// platform enforces this restriction using the application-identifier
// entitlement that each application bundle should have. See
// https://developer.apple.com/documentation/security/1401659-secitemadd?language=objc#discussion
// The keychain does not overwrite secrets by default (unlike other backends
// like libsecret and credential manager). To be consistent, we first delete
// any previously-stored secrets that use the given label.
nsresult rv = DeleteSecret(aLabel);
if (NS_FAILED(rv)) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("DeleteSecret before StoreSecret failed"));
return rv;
}
const CFStringRef keys[] = {kSecClass, kSecAttrAccount, kSecValueData};
ScopedCFType<CFStringRef> label(MozillaStringToCFString(aLabel));
if (!label) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("MozillaStringToCFString failed"));
return NS_ERROR_FAILURE;
}
ScopedCFType<CFDataRef> secret(CFDataCreate(
nullptr, reinterpret_cast<const UInt8*>(aSecret.BeginReading()),
aSecret.Length()));
if (!secret) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug, ("CFDataCreate failed"));
return NS_ERROR_FAILURE;
}
const void* values[] = {kSecClassGenericPassword, label.get(), secret.get()};
static_assert(std::size(keys) == std::size(values),
"mismatched SecItemAdd key/value array sizes");
ScopedCFType<CFDictionaryRef> addDictionary(CFDictionaryCreate(
nullptr, (const void**)&keys, (const void**)&values, std::size(keys),
&kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks));
// https://developer.apple.com/documentation/security/1401659-secitemadd
OSStatus osrv = SecItemAdd(addDictionary.get(), nullptr);
if (osrv != errSecSuccess) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("SecItemAdd failed: %d", osrv));
nsPrintfCString osrvString("%d", osrv);
mozilla::glean::oskeystore::ReturnCodesExtra extra = {};
extra.function = Some("StoreSecret_SecItemAdd"_ns);
extra.result = Some(osrvString);
glean::oskeystore::return_codes.Record(Some(extra));
return NS_ERROR_FAILURE;
}
return NS_OK;
}
nsresult KeychainSecret::DeleteSecret(const nsACString& aLabel) {
// To delete a secret, we create a CFDictionary of the form:
// { class: generic password,
// account: the given label }
// and then call SecItemDelete.
const CFStringRef keys[] = {kSecClass, kSecAttrAccount};
ScopedCFType<CFStringRef> label(MozillaStringToCFString(aLabel));
if (!label) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("MozillaStringToCFString failed"));
return NS_ERROR_FAILURE;
}
const void* values[] = {kSecClassGenericPassword, label.get()};
static_assert(std::size(keys) == std::size(values),
"mismatched SecItemDelete key/value array sizes");
ScopedCFType<CFDictionaryRef> deleteDictionary(CFDictionaryCreate(
nullptr, (const void**)&keys, (const void**)&values, std::size(keys),
&kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks));
// https://developer.apple.com/documentation/security/1395547-secitemdelete
OSStatus osrv = SecItemDelete(deleteDictionary.get());
if (osrv != errSecSuccess && osrv != errSecItemNotFound) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("SecItemDelete failed: %d", osrv));
mozilla::glean::oskeystore::ReturnCodesExtra extra = {};
extra.function = Some("DeleteSecret_SecItemDelete"_ns);
nsPrintfCString osrvString("%d", osrv);
extra.result = Some(osrvString);
glean::oskeystore::return_codes.Record(Some(extra));
return NS_ERROR_FAILURE;
}
return NS_OK;
}
nsresult KeychainSecret::RetrieveSecret(const nsACString& aLabel,
/* out */ nsACString& aSecret) {
// To retrieve a secret, we create a CFDictionary of the form:
// { class: generic password,
// account: the given label,
// match limit: match one,
// return attributes: true,
// return data: true }
// This searches for and returns the attributes and data for the secret
// matching the given label. We then extract the data (i.e. the secret) and
// return it.
const CFStringRef keys[] = {kSecClass, kSecAttrAccount, kSecMatchLimit,
kSecReturnAttributes, kSecReturnData};
ScopedCFType<CFStringRef> label(MozillaStringToCFString(aLabel));
if (!label) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("MozillaStringToCFString failed"));
return NS_ERROR_FAILURE;
}
const void* values[] = {kSecClassGenericPassword, label.get(),
kSecMatchLimitOne, kCFBooleanTrue, kCFBooleanTrue};
static_assert(std::size(keys) == std::size(values),
"mismatched SecItemCopyMatching key/value array sizes");
ScopedCFType<CFDictionaryRef> searchDictionary(CFDictionaryCreate(
nullptr, (const void**)&keys, (const void**)&values, std::size(keys),
&kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks));
CFTypeRef item;
// https://developer.apple.com/documentation/security/1398306-secitemcopymatching
OSStatus osrv = SecItemCopyMatching(searchDictionary.get(), &item);
if (osrv == errSecItemNotFound) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("Key not found in key store"));
return NS_ERROR_NOT_AVAILABLE;
}
if (osrv != errSecSuccess) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("SecItemCopyMatching failed: %d", osrv));
mozilla::glean::oskeystore::ReturnCodesExtra extra = {};
extra.function = Some("RetrieveSecret_SecItemCopyMatching"_ns);
nsPrintfCString osrvString("%d", osrv);
extra.result = Some(osrvString);
glean::oskeystore::return_codes.Record(Some(extra));
return NS_ERROR_FAILURE;
}
ScopedCFType<CFDictionaryRef> dictionary(
reinterpret_cast<CFDictionaryRef>(item));
CFDataRef secret = reinterpret_cast<CFDataRef>(
CFDictionaryGetValue(dictionary.get(), kSecValueData));
if (!secret) {
MOZ_LOG(gKeychainSecretLog, LogLevel::Debug,
("CFDictionaryGetValue failed"));
return NS_ERROR_FAILURE;
}
aSecret.Assign(reinterpret_cast<const char*>(CFDataGetBytePtr(secret)),
CFDataGetLength(secret));
return NS_OK;
}
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