/*	$OpenBSD: ssl.c,v 1.31 2017/01/09 14:49:21 reyk Exp $	*/

/*
 * Copyright (c) 2007 - 2014 Reyk Floeter <reyk@openbsd.org>
 * Copyright (c) 2006 Pierre-Yves Ritschard <pyr@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <event.h>
#include <unistd.h>
#include <string.h>
#include <imsg.h>

#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/engine.h>

#include "relayd.h"

void	ssl_read(int, short, void *);
void	ssl_write(int, short, void *);
void	ssl_connect(int, short, void *);
void	ssl_cleanup(struct ctl_tcp_event *);
int	ssl_password_cb(char *, int, int, void *);

void
ssl_read(int s, short event, void *arg)
{
	char			 rbuf[SMALL_READ_BUF_SIZE];
	struct ctl_tcp_event	*cte = arg;
	int			 retry_flag = EV_READ;
	int			 tls_err = 0;
	int			 ret;

	if (event == EV_TIMEOUT) {
		cte->host->up = HOST_DOWN;
		ssl_cleanup(cte);
		hce_notify_done(cte->host, HCE_TLS_READ_TIMEOUT);
		return;
	}

	bzero(rbuf, sizeof(rbuf));

	ret = SSL_read(cte->ssl, rbuf, sizeof(rbuf));
	if (ret <= 0) {
		tls_err = SSL_get_error(cte->ssl, ret);
		switch (tls_err) {
		case SSL_ERROR_WANT_READ:
			retry_flag = EV_READ;
			goto retry;
		case SSL_ERROR_WANT_WRITE:
			retry_flag = EV_WRITE;
			goto retry;
		case SSL_ERROR_ZERO_RETURN: /* FALLTHROUGH */
		case SSL_ERROR_SYSCALL:
			if (ret == 0) {
				cte->host->up = HOST_DOWN;
				(void)cte->validate_close(cte);
				ssl_cleanup(cte);
				hce_notify_done(cte->host, cte->host->he);
				return;
			}
			/* FALLTHROUGH */
		default:
			cte->host->up = HOST_DOWN;
			ssl_error(cte->host->conf.name, "cannot read");
			ssl_cleanup(cte);
			hce_notify_done(cte->host, HCE_TLS_READ_ERROR);
			break;
		}
		return;
	}
	if (ibuf_add(cte->buf, rbuf, ret) == -1)
		fatal("ssl_read: buf_add error");
	if (cte->validate_read != NULL) {
		if (cte->validate_read(cte) != 0)
			goto retry;

		ssl_cleanup(cte);
		hce_notify_done(cte->host, cte->host->he);
		return;
	}

retry:
	event_again(&cte->ev, s, EV_TIMEOUT|retry_flag, ssl_read,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
	return;
}

void
ssl_write(int s, short event, void *arg)
{
	struct ctl_tcp_event	*cte = arg;
	int			 retry_flag = EV_WRITE;
	int			 tls_err = 0;
	int			 len;
	int			 ret;

	if (event == EV_TIMEOUT) {
		cte->host->up = HOST_DOWN;
		ssl_cleanup(cte);
		hce_notify_done(cte->host, HCE_TLS_WRITE_TIMEOUT);
		return;
	}

	len = strlen(cte->table->sendbuf);

	ret = SSL_write(cte->ssl, cte->table->sendbuf, len);
	if (ret <= 0) {
		tls_err = SSL_get_error(cte->ssl, ret);
		switch (tls_err) {
		case SSL_ERROR_WANT_READ:
			retry_flag = EV_READ;
			goto retry;
		case SSL_ERROR_WANT_WRITE:
			retry_flag = EV_WRITE;
			goto retry;
		default:
			cte->host->up = HOST_DOWN;
			ssl_error(cte->host->conf.name, "cannot write");
			ssl_cleanup(cte);
			hce_notify_done(cte->host, HCE_TLS_WRITE_ERROR);
			return;
		}
	}
	if ((cte->buf = ibuf_dynamic(SMALL_READ_BUF_SIZE, UINT_MAX)) == NULL)
		fatalx("ssl_write: cannot create dynamic buffer");

	event_again(&cte->ev, s, EV_TIMEOUT|EV_READ, ssl_read,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
	return;
retry:
	event_again(&cte->ev, s, EV_TIMEOUT|retry_flag, ssl_write,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
}

void
ssl_connect(int s, short event, void *arg)
{
	struct ctl_tcp_event	*cte = arg;
	int			 retry_flag = 0;
	int			 tls_err = 0;
	int			 ret;

	if (event == EV_TIMEOUT) {
		cte->host->up = HOST_DOWN;
		hce_notify_done(cte->host, HCE_TLS_CONNECT_TIMEOUT);
		ssl_cleanup(cte);
		return;
	}

	ret = SSL_connect(cte->ssl);
	if (ret <= 0) {
		tls_err = SSL_get_error(cte->ssl, ret);
		switch (tls_err) {
		case SSL_ERROR_WANT_READ:
			retry_flag = EV_READ;
			goto retry;
		case SSL_ERROR_WANT_WRITE:
			retry_flag = EV_WRITE;
			goto retry;
		default:
			cte->host->up = HOST_DOWN;
			ssl_error(cte->host->conf.name, "cannot connect");
			hce_notify_done(cte->host, HCE_TLS_CONNECT_FAIL);
			ssl_cleanup(cte);
			return;
		}
	}

	if (cte->table->conf.check == CHECK_TCP) {
		cte->host->up = HOST_UP;
		hce_notify_done(cte->host, HCE_TLS_CONNECT_OK);
		ssl_cleanup(cte);
		return;
	}
	if (cte->table->sendbuf != NULL) {
		event_again(&cte->ev, cte->s, EV_TIMEOUT|EV_WRITE, ssl_write,
		    &cte->tv_start, &cte->table->conf.timeout, cte);
		return;
	}

	if ((cte->buf = ibuf_dynamic(SMALL_READ_BUF_SIZE, UINT_MAX)) == NULL)
		fatalx("ssl_connect: cannot create dynamic buffer");
	event_again(&cte->ev, cte->s, EV_TIMEOUT|EV_READ, ssl_read,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
	return;

retry:
	event_again(&cte->ev, s, EV_TIMEOUT|retry_flag, ssl_connect,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
}

void
ssl_cleanup(struct ctl_tcp_event *cte)
{
	close(cte->s);
	if (cte->ssl != NULL) {
		SSL_shutdown(cte->ssl);
		SSL_clear(cte->ssl);
	}
	ibuf_free(cte->buf);
	cte->buf = NULL;
}

void
ssl_error(const char *where, const char *what)
{
	char		 errbuf[128];
	unsigned long	 code;

	if (log_getverbose() < 2)
		return;
	for (; (code = ERR_get_error()) != 0 ;) {
		ERR_error_string_n(code, errbuf, sizeof(errbuf));
		log_debug("SSL library error: %s: %s: %s", where, what, errbuf);
	}
}

void
ssl_init(struct relayd *env)
{
	static int	 initialized = 0;

	if (initialized)
		return;

	SSL_library_init();
	SSL_load_error_strings();

	/* Init hardware crypto engines. */
	ENGINE_load_builtin_engines();
	ENGINE_register_all_complete();

	initialized = 1;
}

void
ssl_transaction(struct ctl_tcp_event *cte)
{
	if (cte->ssl == NULL) {
		cte->ssl = SSL_new(cte->table->ssl_ctx);
		if (cte->ssl == NULL) {
			ssl_error(cte->host->conf.name, "cannot create object");
			fatal("cannot create SSL object");
		}
	}

	if (SSL_set_fd(cte->ssl, cte->s) == 0) {
		cte->host->up = HOST_UNKNOWN;
		ssl_error(cte->host->conf.name, "cannot set fd");
		ssl_cleanup(cte);
		hce_notify_done(cte->host, HCE_TLS_CONNECT_ERROR);
		return;
	}
	SSL_set_connect_state(cte->ssl);

	event_again(&cte->ev, cte->s, EV_TIMEOUT|EV_WRITE, ssl_connect,
	    &cte->tv_start, &cte->table->conf.timeout, cte);
}

SSL_CTX *
ssl_ctx_create(struct relayd *env)
{
	SSL_CTX	*ctx;

	ctx = SSL_CTX_new(SSLv23_client_method());
	if (ctx == NULL) {
		ssl_error("ssl_ctx_create", "cannot create context");
		fatal("could not create SSL context");
	}
	return (ctx);
}

int
ssl_password_cb(char *buf, int size, int rwflag, void *u)
{
	size_t	len;
	if (u == NULL) {
		bzero(buf, size);
		return (0);
	}
	if ((len = strlcpy(buf, u, size)) >= (size_t)size)
		return (0);
	return (len);
}

char *
ssl_load_key(struct relayd *env, const char *name, off_t *len, char *pass)
{
	FILE		*fp;
	EVP_PKEY	*key = NULL;
	BIO		*bio = NULL;
	long		 size;
	char		*data, *buf = NULL;

	/* Initialize SSL library once */
	ssl_init(env);

	/*
	 * Read (possibly) encrypted key from file
	 */
	if ((fp = fopen(name, "r")) == NULL)
		return (NULL);

	key = PEM_read_PrivateKey(fp, NULL, ssl_password_cb, pass);
	fclose(fp);
	if (key == NULL)
		goto fail;

	/*
	 * Write unencrypted key to memory buffer
	 */
	if ((bio = BIO_new(BIO_s_mem())) == NULL)
		goto fail;
	if (!PEM_write_bio_PrivateKey(bio, key, NULL, NULL, 0, NULL, NULL))
		goto fail;
	if ((size = BIO_get_mem_data(bio, &data)) <= 0)
		goto fail;
	if ((buf = calloc(1, size)) == NULL)
		goto fail;
	memcpy(buf, data, size);

	BIO_free_all(bio);
	EVP_PKEY_free(key);

	*len = (off_t)size;
	return (buf);

 fail:
	ssl_error(__func__, name);

	free(buf);
	if (bio != NULL)
		BIO_free_all(bio);
	if (key != NULL)
		EVP_PKEY_free(key);
	return (NULL);
}

X509 *
ssl_update_certificate(X509 *oldcert, EVP_PKEY *pkey, EVP_PKEY *capkey,
    X509 *cacert)
{
	char		 name[2][TLS_NAME_SIZE];
	X509		*cert = NULL;

	name[0][0] = name[1][0] = '\0';
	if (!X509_NAME_oneline(X509_get_subject_name(oldcert),
	    name[0], sizeof(name[0])) ||
	    !X509_NAME_oneline(X509_get_issuer_name(oldcert),
	    name[1], sizeof(name[1])))
		goto done;

	if ((cert = X509_dup(oldcert)) == NULL)
		goto done;

	/* Update certificate key and use our CA as the issuer */
	X509_set_pubkey(cert, pkey);
	X509_set_issuer_name(cert, X509_get_subject_name(cacert));

	/* Sign with our CA */
	if (!X509_sign(cert, capkey, EVP_sha1())) {
		X509_free(cert);
		cert = NULL;
	}

#if DEBUG_CERT
	log_debug("%s: subject %s", __func__, name[0]);
	log_debug("%s: issuer %s", __func__, name[1]);
#if DEBUG > 2
	X509_print_fp(stdout, cert);
#endif
#endif

 done:
	if (cert == NULL)
		ssl_error(__func__, name[0]);

	return (cert);
}

int
ssl_load_pkey(const void *data, size_t datalen, char *buf, off_t len,
    X509 **x509ptr, EVP_PKEY **pkeyptr)
{
	BIO		*in;
	X509		*x509 = NULL;
	EVP_PKEY	*pkey = NULL;
	RSA		*rsa = NULL;
	void		*exdata = NULL;

	if ((in = BIO_new_mem_buf(buf, len)) == NULL) {
		SSLerr(SSL_F_SSL_CTX_USE_PRIVATEKEY, ERR_R_BUF_LIB);
		return (0);
	}

	if ((x509 = PEM_read_bio_X509(in, NULL,
	    ssl_password_cb, NULL)) == NULL) {
		SSLerr(SSL_F_SSL_CTX_USE_PRIVATEKEY, ERR_R_PEM_LIB);
		goto fail;
	}

	if ((pkey = X509_get_pubkey(x509)) == NULL) {
		SSLerr(SSL_F_SSL_CTX_USE_PRIVATEKEY, ERR_R_X509_LIB);
		goto fail;
	}

	BIO_free(in);

	if (data != NULL && datalen) {
		if ((rsa = EVP_PKEY_get1_RSA(pkey)) == NULL ||
		    (exdata = malloc(datalen)) == NULL) {
			SSLerr(SSL_F_SSL_CTX_USE_PRIVATEKEY, ERR_R_EVP_LIB);
			goto fail;
		}

		memcpy(exdata, data, datalen);
		RSA_set_ex_data(rsa, 0, exdata);
		RSA_free(rsa); /* dereference, will be cleaned up with pkey */
	}

	*x509ptr = x509;
	*pkeyptr = pkey;

	return (1);

 fail:
	if (rsa != NULL)
		RSA_free(rsa);
	if (in != NULL)
		BIO_free(in);
	if (pkey != NULL)
		EVP_PKEY_free(pkey);
	if (x509 != NULL)
		X509_free(x509);
	free(exdata);

	return (0);
}

int
ssl_ctx_fake_private_key(SSL_CTX *ctx, const void *data, size_t datalen,
    char *buf, off_t len, X509 **x509ptr, EVP_PKEY **pkeyptr)
{
	int		 ret = 0;
	EVP_PKEY	*pkey = NULL;
	X509		*x509 = NULL;

	if (!ssl_load_pkey(data, datalen, buf, len, &x509, &pkey))
		return (0);

	/*
	 * Use the public key as the "private" key - the secret key
	 * parameters are hidden in an extra process that will be
	 * contacted by the RSA engine.  The SSL/TLS library needs at
	 * least the public key parameters in the current process.
	 */
	ret = SSL_CTX_use_PrivateKey(ctx, pkey);
	if (!ret)
		SSLerr(SSL_F_SSL_CTX_USE_PRIVATEKEY, ERR_R_SSL_LIB);

	if (pkeyptr != NULL)
		*pkeyptr = pkey;
	else if (pkey != NULL)
		EVP_PKEY_free(pkey);

	if (x509ptr != NULL)
		*x509ptr = x509;
	else if (x509 != NULL)
		X509_free(x509);

	return (ret);
}