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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "VerityUtils"
#include <android-base/unique_fd.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <linux/fsverity.h>
#include <linux/stat.h>
#include <nativehelper/JNIHelp.h>
#include <nativehelper/ScopedPrimitiveArray.h>
#include <nativehelper/ScopedUtfChars.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <utils/Log.h>
#include <type_traits>
#include "jni.h"
namespace android {
namespace {
int enableFsverity(JNIEnv *env, jobject /* clazz */, jstring filePath, jbyteArray signature) {
ScopedUtfChars path(env, filePath);
if (path.c_str() == nullptr) {
return EINVAL;
}
::android::base::unique_fd rfd(open(path.c_str(), O_RDONLY | O_CLOEXEC));
if (rfd.get() < 0) {
return errno;
}
ScopedByteArrayRO signature_bytes(env, signature);
if (signature_bytes.get() == nullptr) {
return EINVAL;
}
fsverity_enable_arg arg = {};
arg.version = 1;
arg.hash_algorithm = FS_VERITY_HASH_ALG_SHA256; // hardcoded in measureFsverity below
arg.block_size = 4096;
arg.salt_size = 0;
arg.salt_ptr = reinterpret_cast<uintptr_t>(nullptr);
arg.sig_size = signature_bytes.size();
arg.sig_ptr = reinterpret_cast<uintptr_t>(signature_bytes.get());
if (ioctl(rfd.get(), FS_IOC_ENABLE_VERITY, &arg) < 0) {
return errno;
}
return 0;
}
// Returns whether the file has fs-verity enabled.
// 0 if it is not present, 1 if is present, and -errno if there was an error.
int statxForFsverity(JNIEnv *env, jobject /* clazz */, jstring filePath) {
ScopedUtfChars path(env, filePath);
// Call statx and check STATX_ATTR_VERITY.
struct statx out = {};
if (statx(AT_FDCWD, path.c_str(), 0 /* flags */, STATX_ALL, &out) != 0) {
return -errno;
}
if (out.stx_attributes_mask & STATX_ATTR_VERITY) {
return (out.stx_attributes & STATX_ATTR_VERITY) != 0;
}
// STATX_ATTR_VERITY is not supported for the file path.
// In this case, call ioctl(FS_IOC_GETFLAGS) and check FS_VERITY_FL.
::android::base::unique_fd rfd(open(path.c_str(), O_RDONLY | O_CLOEXEC));
if (rfd.get() < 0) {
ALOGE("open failed at %s", path.c_str());
return -errno;
}
unsigned int flags;
if (ioctl(rfd.get(), FS_IOC_GETFLAGS, &flags) < 0) {
ALOGE("ioctl(FS_IOC_GETFLAGS) failed at %s", path.c_str());
return -errno;
}
return (flags & FS_VERITY_FL) != 0;
}
int measureFsverity(JNIEnv *env, jobject /* clazz */, jstring filePath, jbyteArray digest) {
static constexpr auto kDigestSha256 = 32;
using Storage = std::aligned_storage_t<sizeof(fsverity_digest) + kDigestSha256>;
Storage bytes;
fsverity_digest *data = reinterpret_cast<fsverity_digest *>(&bytes);
data->digest_size = kDigestSha256; // the only input/output parameter
ScopedUtfChars path(env, filePath);
::android::base::unique_fd rfd(open(path.c_str(), O_RDONLY | O_CLOEXEC));
if (rfd.get() < 0) {
return rfd.get();
}
if (auto err = ioctl(rfd.get(), FS_IOC_MEASURE_VERITY, data); err < 0) {
return err;
}
if (data->digest_algorithm != FS_VERITY_HASH_ALG_SHA256) {
return -EINVAL;
}
if (digest != nullptr && data->digest_size > 0) {
auto digestSize = env->GetArrayLength(digest);
if (data->digest_size > digestSize) {
return -E2BIG;
}
env->SetByteArrayRegion(digest, 0, data->digest_size, (const jbyte *)data->digest);
}
return 0;
}
const JNINativeMethod sMethods[] = {
{"enableFsverityNative", "(Ljava/lang/String;[B)I", (void *)enableFsverity},
{"statxForFsverityNative", "(Ljava/lang/String;)I", (void *)statxForFsverity},
{"measureFsverityNative", "(Ljava/lang/String;[B)I", (void *)measureFsverity},
};
} // namespace
int register_com_android_internal_security_VerityUtils(JNIEnv *env) {
return jniRegisterNativeMethods(env, "com/android/internal/security/VerityUtils", sMethods,
NELEM(sMethods));
}
} // namespace android
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