key_enable/src/key_enable.rs

/*
 * Copyright (c) 2023 Huawei Device Co., Ltd.
 * 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.
 */

use super::cert_chain_utils::PemCollection;
use super::cert_path_utils::TrustCertPath;
use super::cert_utils::{get_cert_path, get_trusted_certs};
use super::cs_hisysevent;
use super::profile_utils::add_profile_cert_path;
use hilog_rust::{error, hilog, info, HiLogLabel, LogType};
use openssl::error::ErrorStack;
use std::ffi::{c_char, CString};
use std::fs::File;
use std::io::{BufRead, BufReader};
use std::option::Option;
use std::ptr;
use std::thread;
use std::time::{Duration, Instant};
use std::path::Path;

const LOG_LABEL: HiLogLabel = HiLogLabel {
    log_type: LogType::LogCore,
    domain: 0xd005a06, // security domain
    tag: "CODE_SIGN",
};

const CERT_DATA_MAX_SIZE: usize = 8192;
const PROC_KEY_FILE_PATH: &str = "/proc/keys";
const KEYRING_TYPE: &str = "keyring";
const FSVERITY_KEYRING_NAME: &str = ".fs-verity";
const LOCAL_KEY_NAME: &str = "local_key";
const CODE_SIGN_KEY_NAME_PREFIX: &str = "fs_verity_key";
const PROFILE_STORE_EL1: &str = "/data/service/el1/public/profiles";
const PROFILE_SEARCH_SLEEP_TIME: u64 = 200;
const PROFILE_SEARCH_SLEEP_OUT_TIME: u64 = 600;
const SUCCESS: i32 = 0;

type KeySerial = i32;

/// key error report to hisysevent
pub enum HisyseventKeyError {
    /// local key empty
    LocalKeyEmpty = 1,
}

extern "C" {
    fn InitLocalCertificate(cert_data: *mut u8, cert_size: *mut usize) -> i32;
    fn AddKey(
        type_name: *const c_char,
        description: *const c_char,
        payload: *const u8,
        plen: usize,
        ring_id: KeySerial,
    ) -> KeySerial;
    fn KeyctlRestrictKeyring(
        ring_id: KeySerial,
        type_name: *const u8,
        restriction: *const u8,
    ) -> KeySerial;
    fn CheckUserUnlock() -> bool;
}

fn print_openssl_error_stack(error_stack: ErrorStack) {
    for error in error_stack.errors() {
        error!(LOG_LABEL, "{}", @public(error.to_string()));
    }
}

fn get_local_key() -> Option<Vec<u8>> {
    let mut cert_size = CERT_DATA_MAX_SIZE;
    let mut cert_data = Vec::with_capacity(cert_size);
    let pcert = cert_data.as_mut_ptr();

    unsafe {
        let ret = InitLocalCertificate(pcert, &mut cert_size);
        if ret == 0 {
            cert_data.set_len(cert_size);
            Some(cert_data)
        } else {
            None
        }
    }
}

/// parse key info
/// [Serial][Flags][Usage][Expiry][Permissions][UID][GID][TypeName][Description]: [Summary]
///   [0]     [1]    [2]    [3]       [4]       [5]  [6]     [7]        [8]         [9]
/// 3985ad4c I------  1    perm     082f0000     0    0    keyring  .fs-verity:   empty
fn parse_key_info(line: String) -> Option<KeySerial> {
    let attrs: Vec<&str> = line.split_whitespace().collect();
    if attrs.len() != 10 {
        return None;
    }
    if attrs[7] == KEYRING_TYPE && attrs[8].strip_suffix(':') == Some(FSVERITY_KEYRING_NAME) {
        match KeySerial::from_str_radix(attrs[0], 16) {
            Ok(x) => Some(x),
            Err(error) => {
                error!(LOG_LABEL, "Convert KeySerial failed: {}", error);
                None
            }
        }
    } else {
        None
    }
}

fn enable_key(key_id: KeySerial, key_name: &str, cert_data: &Vec<u8>) -> i32 {
    let type_name = CString::new("asymmetric").expect("type name is invalid");
    let keyname = CString::new(key_name).expect("keyname is invalid");
    unsafe {
        let ret: i32 = AddKey(
            type_name.as_ptr(),
            keyname.as_ptr(),
            cert_data.as_ptr(),
            cert_data.len(),
            key_id,
        );
        ret
    }
}

fn enable_key_list(key_id: KeySerial, certs: Vec<Vec<u8>>, key_name_prefix: &str) -> i32 {
    let prefix = String::from(key_name_prefix);
    for (i, cert_data) in certs.iter().enumerate() {
        let key_name = prefix.clone() + &i.to_string();
        let ret = enable_key(key_id, key_name.as_str(), cert_data);
        if ret < 0 {
            return ret;
        }
    }
    SUCCESS
}

/// parse proc_key_file to get keyring id
fn get_keyring_id() -> Result<KeySerial, ()> {
    let file = File::open(PROC_KEY_FILE_PATH).expect("Open /proc/keys failed");
    let lines = BufReader::new(file).lines();
    for line in lines.flatten() {
        if line.contains(KEYRING_TYPE) && line.contains(FSVERITY_KEYRING_NAME) {
            if let Some(keyid) = parse_key_info(line) {
                return Ok(keyid);
            }
        }
    }
    error!(LOG_LABEL, "Get .fs-verity keyring id failed.");
    Err(())
}

// enable all trusted keys
fn enable_trusted_keys(key_id: KeySerial, root_cert: &PemCollection) {
    let certs = match root_cert.to_der() {
        Ok(der) => der,
        Err(e) => {
            print_openssl_error_stack(e);
            Vec::new()
        }
    };
    if certs.is_empty() {
        error!(LOG_LABEL, "empty trusted certs!");
    }
    let ret = enable_key_list(key_id, certs, CODE_SIGN_KEY_NAME_PREFIX);
    if ret < 0 {
        cs_hisysevent::report_add_key_err("code_sign_keys", ret);
    }
}

fn check_and_add_cert_path(root_cert: &PemCollection, cert_paths: &TrustCertPath) -> bool {
    if Path::new(PROFILE_STORE_EL1).exists() {
        if add_profile_cert_path(root_cert, cert_paths).is_err() {
            error!(LOG_LABEL, "Add cert path from local profile err.");
        }
        info!(LOG_LABEL, "Finished cert path adding.");
        true
    } else {
        false
    }
}

// start cert path ops thread add trusted cert & developer cert
fn add_profile_cert_path_thread(
    root_cert: PemCollection,
    cert_paths: TrustCertPath,
) -> std::thread::JoinHandle<()> {
    thread::spawn(move || {
        // enable developer certs
        info!(LOG_LABEL, "Starting enable developer cert.");
        let start_time = Instant::now();
        loop {
            if check_and_add_cert_path(&root_cert, &cert_paths) {
                break;
            } else if start_time.elapsed() >= Duration::from_secs(PROFILE_SEARCH_SLEEP_OUT_TIME) {
                error!(LOG_LABEL, "Timeout while waiting for PROFILE_STORE_EL1.");
                break;
            } else {
                thread::sleep(Duration::from_millis(PROFILE_SEARCH_SLEEP_TIME));
            }
        }
    })
}

// enable local key from local code sign SA
fn enable_local_key(key_id: KeySerial) {
    if let Some(cert_data) = get_local_key() {
        let ret = enable_key(key_id, LOCAL_KEY_NAME, &cert_data);
        if ret < 0 {
            cs_hisysevent::report_add_key_err("local_key", ret);
            error!(LOG_LABEL, "Enable local key failed");
        }
    } else {
        cs_hisysevent::report_add_key_err("local_key", HisyseventKeyError::LocalKeyEmpty as i32);
        info!(LOG_LABEL, "Get local key empty.");
    }
}

// restrict fs-verity keyring, don't allow to add more keys
fn restrict_keys(key_id: KeySerial) {
    unsafe {
        if KeyctlRestrictKeyring(key_id, ptr::null(), ptr::null()) < 0 {
            error!(LOG_LABEL, "Restrict keyring err");
        }
    }
}

fn enable_keys_after_user_unlock(key_id: KeySerial) {
    if !unsafe { CheckUserUnlock() } {
        restrict_keys(key_id);
        return;
    }

    // enable local code sign key
    enable_local_key(key_id);
    restrict_keys(key_id);
}

/// enable trusted and local keys, and then restrict keyring
pub fn enable_all_keys() {
    let key_id = match get_keyring_id() {
        Ok(id) => id,
        Err(_) => {
            error!(LOG_LABEL, "Failed to get keyring ID.");
            return;
        },
    };
    let root_cert = get_trusted_certs();
    // enable device keys and authed source
    enable_trusted_keys(key_id, &root_cert);

    let cert_paths = get_cert_path();
    // enable trusted cert in prebuilt config
    if cert_paths.add_cert_paths().is_err() {
        error!(LOG_LABEL, "Add trusted cert path err.");
    }

    let cert_thread = add_profile_cert_path_thread(root_cert, cert_paths);
    enable_keys_after_user_unlock(key_id);

    if let Err(e) = cert_thread.join() {
        error!(LOG_LABEL, "add cert path thread panicked: {:?}", e);
    }
    info!(LOG_LABEL, "Fnished enable all keys.");
}