viossl.cc

/* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
   http://oss.oracle.com/licenses/universal-foss-exception.

   This program 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 General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/*
  Note that we can't have assertion on file descriptors;  The reason for
  this is that during mysql shutdown, another thread can close a file
  we are working on.  In this case we should just return read errors from
  the file descriptior.
*/

#include <errno.h>
#include <stddef.h>

#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "mysql/psi/mysql_socket.h"
#include "vio/vio_priv.h"

/* clang-format off */
/**
  @page page_protocol_basic_tls TLS

  The MySQL Protocol also supports encryption and authentication via TLS.
  The encryption is transparent to the rest of the protocol and is applied
  after the data is compressed right before the data is written to
  the network layer.

  The TLS suppport is announced in
  @ref page_protocol_connection_phase_packets_protocol_handshake sent by the
  server via ::CLIENT_SSL and is enabled if the client returns the same
  capability.

  For an unencrypted connection the server starts with its
  @ref page_protocol_connection_phase_packets_protocol_handshake :

  ~~~~~~~
  36 00 00 00 0a 35 2e 35    2e 32 2d 6d 32 00 52 00    6....5.5.2-m2.R.
  00 00 22 3d 4e 50 29 75    39 56 00 ff ff 08 02 00    .."=NP)u9V......
  00 00 00 00 00 00 00 00    00 00 00 00 00 29 64 40    .............)d@
  52 5c 55 78 7a 7c 21 29    4b 00                      R\Uxz|!)K.
  ~~~~~~~

  ... and the client returns its
  @ref page_protocol_connection_phase_packets_protocol_handshake_response

  ~~~~~~~
  3a 00 00 01 05 a6 03 00    00 00 00 01 08 00 00 00    :...............
  00 00 00 00 00 00 00 00    00 00 00 00 00 00 00 00    ................
  00 00 00 00 72 6f 6f 74    00 14 14 63 6b 70 99 8a    ....root...ckp..
  b6 9e 96 87 a2 30 9a 40    67 2b 83 38 85 4b          .....0.@g+.8.K
  ~~~~~~~

  If client wants to do TLS and the server supports it, it would send a
  @ref page_protocol_connection_phase_packets_protocol_ssl_request with
  ::CLIENT_SSL capability enabled.

  ~~~~~~~
  20 00 00 01 05 ae 03 00    00 00 00 01 08 00 00 00     ...............
  00 00 00 00 00 00 00 00    00 00 00 00 00 00 00 00    ................
  00 00 00 00                                           ....
  ~~~~~~~

  Then the rest of the communication is swithed to TLS:
  ~~~~~~~
  16 03 01 00 5e 01 00 00    5a 03 01 4c a3 49 2e 7a    ....^...Z..L.I.z
  b5 06 75 68 5c 30 36 73    f1 82 79 70 58 4c 64 bb    ..uh\06s..ypXLd.
  47 7e 90 cd 9b 30 c5 66    65 da 35 00 00 2c 00 39    G~...0.fe.5..,.9
  00 38 00 35 00 16 00 13    00 0a 00 33 00 32 00 2f    .8.5.......3.2./
  00 9a 00 99 00 96 00 05    00 04 00 15 00 12 00 09    ................
  00 14 00 11 00 08 00 06    00 03 02 01 00 00 04 00    ................
  23 00 00                                              #..
  ~~~~~~~

  The preceding packet is from SSL_connect() which does the
  [TLS handshake](https://en.wikipedia.org/wiki/Transport_Layer_Security#TLS_handshake)

  Once the TLS tunnel is established the normal communication continues
  starting with the client sending the
  @ref page_protocol_connection_phase_packets_protocol_handshake_response

  See @ref sect_protocol_connection_phase_initial_handshake_ssl_handshake
  for a diagram of the exchange.

  @sa cli_establish_ssl, parse_client_handshake_packet
*/
/* clang-format on */

#ifdef HAVE_OPENSSL

#ifndef DBUG_OFF

static void report_errors(SSL *ssl) {
  unsigned long l;
  const char *file;
  const char *data;
  int line, flags = 0;
  char buf[512];

  DBUG_ENTER("report_errors");

  while ((l = ERR_get_error_line_data(&file, &line, &data, &flags))) {
    DBUG_PRINT("error", ("OpenSSL: %s:%s:%d:%s\n", ERR_error_string(l, buf),
                         file, line, (flags & ERR_TXT_STRING) ? data : ""));
  }

  if (ssl)
    DBUG_PRINT("error",
               ("error: %s", ERR_error_string(SSL_get_error(ssl, l), buf)));

  DBUG_PRINT("info", ("socket_errno: %d", socket_errno));
  DBUG_VOID_RETURN;
}

#endif

/**
  Obtain the equivalent system error status for the last SSL I/O operation.

  @param ssl_error  The result code of the failed TLS/SSL I/O operation.
*/

static void ssl_set_sys_error(int ssl_error) {
  int error = 0;

  switch (ssl_error) {
    case SSL_ERROR_ZERO_RETURN:
      error = SOCKET_ECONNRESET;
      break;
    case SSL_ERROR_WANT_READ:
    case SSL_ERROR_WANT_WRITE:
#ifdef SSL_ERROR_WANT_CONNECT
    case SSL_ERROR_WANT_CONNECT:
#endif
#ifdef SSL_ERROR_WANT_ACCEPT
    case SSL_ERROR_WANT_ACCEPT:
#endif
      error = SOCKET_EWOULDBLOCK;
      break;
    case SSL_ERROR_SSL:
      /* Protocol error. */
#ifdef EPROTO
      error = EPROTO;
#else
      error = SOCKET_ECONNRESET;
#endif
      break;
    case SSL_ERROR_SYSCALL:
    case SSL_ERROR_NONE:
    default:
      break;
  };

  /* Set error status to a equivalent of the SSL error. */
  if (error) {
#ifdef _WIN32
    WSASetLastError(error);
#else
    errno = error;
#endif
  }
}

/**
  Check if an operation should be retried and handle errors

  This function does the following:
    - it indicates whether a SSL I/O operation must be retried later;
    - if DBUG is enabled it prints all the errors in the thread's queue to DBUG
    - it clears the OpenSSL error queue, thus the next OpenSSL-operation can be
      performed even after failed OpenSSL-call.

  Note that this is not done for SSL_ERROR_WANT_READ/SSL_ERROR_WANT_WRITE
  since these are not treated as errors and a call to the function is retried.

  When SSL_ERROR_SSL is returned the ERR code of the top error in the queue is
  peeked and returned to the caller so they can call ERR_error_string_n() and
  retrieve the right error message.

  @param vio  VIO object representing a SSL connection.
  @param ret  Value returned by a SSL I/O function.
  @param [out] event             The type of I/O event to wait/retry.
  @param [out] ssl_errno_holder  The SSL error code.

  @return Whether a SSL I/O operation should be deferred.
  @retval true    Temporary failure, retry operation.
  @retval false   Indeterminate failure.
*/

static bool ssl_should_retry(Vio *vio, int ret, enum enum_vio_io_event *event,
                             unsigned long *ssl_errno_holder) {
  int ssl_error, err_error;
  SSL *ssl = static_cast<SSL *>(vio->ssl_arg);
  bool should_retry = true;

  /* Retrieve the result for the SSL I/O operation. */
  ssl_error = SSL_get_error(ssl, ret);

  /* Retrieve the result for the SSL I/O operation. */
  switch (ssl_error) {
    case SSL_ERROR_WANT_READ:
      err_error = ssl_error;  // for backward compatibility.
      *event = VIO_IO_EVENT_READ;
      break;
    case SSL_ERROR_WANT_WRITE:
      err_error = ssl_error;  // for backward compatibility.
      *event = VIO_IO_EVENT_WRITE;
      break;
    default:
      /* first save the top ERR error */
#ifdef HAVE_WOLFSSL
      /* TODO: when wolfSSL issue 4240 is fixed (see bug 27855668) remove the
       * "if" branch */
      err_error = ssl_error;
#else
      err_error = ERR_get_error();
#endif
      /* now report all remaining errors on and/or clear the error stack */
#ifndef DBUG_OFF /* Debug build */
      /* Note: the OpenSSL error queue gets cleared in report_errors(). */
      report_errors(ssl);
#else /* Release build */
      ERR_clear_error();
#endif
      should_retry = false;
      ssl_set_sys_error(ssl_error);
      break;
  }

  *ssl_errno_holder = err_error;

  return should_retry;
}

#ifdef HAVE_WOLFSSL
size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size) {
  // YASSL maps ETIMEOUT to EWOULDBLOCK and hence no need for retry here.
  return SSL_read(static_cast<SSL *>(vio->ssl_arg), buf, (int)size);
}
#else
size_t vio_ssl_read(Vio *vio, uchar *buf, size_t size) {
  int ret;
  SSL *ssl = static_cast<SSL *>(vio->ssl_arg);
  unsigned long ssl_errno_not_used;

  DBUG_ENTER("vio_ssl_read");

  while (1) {
    enum enum_vio_io_event event;

    /*
      Check that the SSL thread's error queue is cleared. Otherwise
      SSL_read() returns an error from the error queue, when SSL_read() failed
      because it would block.
    */
    DBUG_ASSERT(ERR_peek_error() == 0);

    ret = SSL_read(ssl, buf, (int)size);

    if (ret >= 0) break;

    /* Process the SSL I/O error. */
    if (!ssl_should_retry(vio, ret, &event, &ssl_errno_not_used)) break;

    if (!vio->is_blocking_flag) {
      switch (event) {
        case VIO_IO_EVENT_READ:
          DBUG_RETURN(VIO_SOCKET_WANT_READ);
        case VIO_IO_EVENT_WRITE:
          DBUG_RETURN(VIO_SOCKET_WANT_WRITE);
        default:
          DBUG_RETURN(VIO_SOCKET_ERROR);
      }
    }

    /* Attempt to wait for an I/O event. */
    if (vio_socket_io_wait(vio, event)) break;
  }

  DBUG_RETURN(ret < 0 ? -1 : ret);
}
#endif

size_t vio_ssl_write(Vio *vio, const uchar *buf, size_t size) {
  int ret;
  SSL *ssl = static_cast<SSL *>(vio->ssl_arg);
  unsigned long ssl_errno_not_used;

  DBUG_ENTER("vio_ssl_write");

  while (1) {
    enum enum_vio_io_event event;

    /*
      check that the SSL thread's error queue is cleared. Otherwise
      SSL_write() returns an error from the error queue, when SSL_write() failed
      because it would block.
    */
    DBUG_ASSERT(ERR_peek_error() == 0);

    ret = SSL_write(ssl, buf, (int)size);

    if (ret >= 0) break;

    /* Process the SSL I/O error. */
    if (!ssl_should_retry(vio, ret, &event, &ssl_errno_not_used)) break;

    if (!vio->is_blocking_flag) {
      switch (event) {
        case VIO_IO_EVENT_READ:
          DBUG_RETURN(VIO_SOCKET_WANT_READ);
        case VIO_IO_EVENT_WRITE:
          DBUG_RETURN(VIO_SOCKET_WANT_WRITE);
        default:
          DBUG_RETURN(VIO_SOCKET_ERROR);
      }
    }

    /* Attempt to wait for an I/O event. */
    if (vio_socket_io_wait(vio, event)) break;
  }

  DBUG_RETURN(ret < 0 ? -1 : ret);
}

int vio_ssl_shutdown(Vio *vio) {
  int r = 0;
  SSL *ssl = (SSL *)vio->ssl_arg;
  DBUG_ENTER("vio_ssl_shutdown");

  if (ssl) {
    /*
    THE SSL standard says that SSL sockets must send and receive a close_notify
    alert on socket shutdown to avoid truncation attacks. However, this can
    cause problems since we often hold a lock during shutdown and this IO can
    take an unbounded amount of time to complete. Since our packets are self
    describing with length, we aren't vunerable to these attacks. Therefore,
    we just shutdown by closing the socket (quiet shutdown).
    */
    SSL_set_quiet_shutdown(ssl, 1);

    switch ((r = SSL_shutdown(ssl))) {
      case 1:
        /* Shutdown successful */
        break;
      case 0:
        /*
          Shutdown not yet finished - since the socket is going to
          be closed there is no need to call SSL_shutdown() a second
          time to wait for the other side to respond
        */
        break;
      default: /* Shutdown failed */
        DBUG_PRINT("vio_error",
                   ("SSL_shutdown() failed, error: %d", SSL_get_error(ssl, r)));
        break;
    }
  }
  DBUG_RETURN(vio_shutdown(vio));
}

void vio_ssl_delete(Vio *vio) {
  if (!vio) return; /* It must be safe to delete null pointer */

  if (vio->inactive == false)
    vio_ssl_shutdown(vio); /* Still open, close connection first */

  if (vio->ssl_arg) {
    SSL_free((SSL *)vio->ssl_arg);
    vio->ssl_arg = 0;
  }

#ifndef HAVE_WOLFSSL
#if OPENSSL_VERSION_NUMBER < 0x10100000L
  ERR_remove_thread_state(0);
#endif /* OPENSSL_VERSION_NUMBER < 0x10100000L */
#endif

  vio_delete(vio);
}

/** SSL handshake handler. */
extern "C" {
typedef int (*ssl_handshake_func_t)(SSL *);
}

/**
  Loop and wait until a SSL handshake is completed.

  @param vio    VIO object representing a SSL connection.
  @param ssl    SSL structure for the connection.
  @param func   SSL handshake handler.
  @param [out] ssl_errno_holder  The SSL error code.

  @return Return value is 1 on success.
*/

static size_t ssl_handshake_loop(Vio *vio, SSL *ssl, ssl_handshake_func_t func,
                                 unsigned long *ssl_errno_holder) {
  DBUG_ENTER(__func__);
  size_t ret = -1;

  vio->ssl_arg = ssl;

  /* Initiate the SSL handshake. */
  while (1) {
    enum enum_vio_io_event event;

    /*
      check that the SSL thread's error queue is cleared. Otherwise
      SSL-handshake-function returns an error from the error queue, when the
      function failed because it would block.
    */
    DBUG_ASSERT(ERR_peek_error() == 0);

    int handshake_ret;
    handshake_ret = func(ssl);

    if (handshake_ret >= 1) {
      ret = 0;
      break;
    }

    /* Process the SSL I/O error. */
    if (!ssl_should_retry(vio, handshake_ret, &event, ssl_errno_holder)) break;

    if (!vio->is_blocking_flag) {
      switch (event) {
        case VIO_IO_EVENT_READ:
          DBUG_RETURN(VIO_SOCKET_WANT_READ);
        case VIO_IO_EVENT_WRITE:
          DBUG_RETURN(VIO_SOCKET_WANT_WRITE);
        default:
          DBUG_RETURN(VIO_SOCKET_ERROR);
      }
    }

    /* Wait for I/O so that the handshake can proceed. */
    if (vio_socket_io_wait(vio, event)) break;
  }

  vio->ssl_arg = NULL;

  DBUG_RETURN(ret);
}

static int ssl_do(struct st_VioSSLFd *ptr, Vio *vio, long timeout,
                  ssl_handshake_func_t func, unsigned long *ssl_errno_holder,
                  SSL **sslptr) {
  SSL *ssl = nullptr;
  my_socket sd = mysql_socket_getfd(vio->mysql_socket);

  /* Declared here to make compiler happy */
#if !defined(HAVE_WOLFSSL) && !defined(DBUG_OFF)
  int j, n;
#endif

  DBUG_ENTER("ssl_do");
  DBUG_PRINT("enter", ("ptr: %p, sd: %d  ctx: %p", ptr, sd, ptr->ssl_context));

  if (!sslptr) {
    sslptr = &ssl;
  }

  if (*sslptr == nullptr) {
    if (!(ssl = SSL_new(ptr->ssl_context))) {
      DBUG_PRINT("error", ("SSL_new failure"));
      *ssl_errno_holder = ERR_get_error();
      DBUG_RETURN(1);
    }

    DBUG_PRINT("info", ("ssl: %p timeout: %ld", ssl, timeout));
    SSL_clear(ssl);
    SSL_SESSION_set_timeout(SSL_get_session(ssl), timeout);
    SSL_set_fd(ssl, sd);
#if !defined(HAVE_WOLFSSL) && defined(SSL_OP_NO_COMPRESSION)
    SSL_set_options(ssl, SSL_OP_NO_COMPRESSION); /* OpenSSL >= 1.0 only */
#elif !defined(HAVE_WOLFSSL) && \
    OPENSSL_VERSION_NUMBER >= 0x00908000L /* workaround for OpenSSL 0.9.8 */
    sk_SSL_COMP_zero(SSL_COMP_get_compression_methods());
#endif

#if !defined(HAVE_WOLFSSL) && !defined(DBUG_OFF)
    {
      STACK_OF(SSL_COMP) *ssl_comp_methods = NULL;
      ssl_comp_methods = SSL_COMP_get_compression_methods();
      n = sk_SSL_COMP_num(ssl_comp_methods);
      DBUG_PRINT("info", ("Available compression methods:\n"));
      if (n == 0)
        DBUG_PRINT("info", ("NONE\n"));
      else
        for (j = 0; j < n; j++) {
          SSL_COMP *c = sk_SSL_COMP_value(ssl_comp_methods, j);
#if OPENSSL_VERSION_NUMBER < 0x10100000L
          DBUG_PRINT("info", ("  %d: %s\n", c->id, c->name));
#else  /* OPENSSL_VERSION_NUMBER < 0x10100000L */
          DBUG_PRINT("info",
                     ("  %d: %s\n", SSL_COMP_get_id(c), SSL_COMP_get0_name(c)));
#endif /* OPENSSL_VERSION_NUMBER < 0x10100000L */
        }
    }
#endif

      /*
        Since yaSSL does not support non-blocking send operations, use
        special transport functions that properly handles non-blocking
        sockets. These functions emulate the behavior of blocking I/O
        operations by waiting for I/O to become available.
      */
#ifdef HAVE_WOLFSSL
    /* Set first argument of the transport functions. */
    wolfSSL_SetIOReadCtx(ssl, vio);
    wolfSSL_SetIOWriteCtx(ssl, vio);
#endif
    *sslptr = ssl;
  } else {
    ssl = *sslptr;
  }

  size_t loop_ret;
  if ((loop_ret = ssl_handshake_loop(vio, ssl, func, ssl_errno_holder))) {
    if (loop_ret != VIO_SOCKET_ERROR) {
      DBUG_RETURN((int)loop_ret);  // Don't free SSL
    }

    DBUG_PRINT("error", ("SSL_connect/accept failure"));
    SSL_free(ssl);
    *sslptr = nullptr;
    DBUG_RETURN((int)VIO_SOCKET_ERROR);
  }

  /*
    Connection succeeded. Install new function handlers,
    change type, set sd to the fd used when connecting
    and set pointer to the SSL structure
  */
  if (vio_reset(vio, VIO_TYPE_SSL, SSL_get_fd(ssl), ssl, 0)) DBUG_RETURN(1);
  if (sslptr != &ssl) {
    *sslptr = nullptr;
  }

#ifndef DBUG_OFF
  {
    /* Print some info about the peer */
    X509 *cert;
    char buf[512];

    DBUG_PRINT("info", ("SSL connection succeeded"));
    DBUG_PRINT("info", ("Using cipher: '%s'", SSL_get_cipher_name(ssl)));

    if ((cert = SSL_get_peer_certificate(ssl))) {
      DBUG_PRINT("info", ("Peer certificate:"));
      X509_NAME_oneline(X509_get_subject_name(cert), buf, sizeof(buf));
      DBUG_PRINT("info", ("\t subject: '%s'", buf));
      X509_NAME_oneline(X509_get_issuer_name(cert), buf, sizeof(buf));
      DBUG_PRINT("info", ("\t issuer: '%s'", buf));
      X509_free(cert);
    } else
      DBUG_PRINT("info", ("Peer does not have certificate."));

    if (SSL_get_shared_ciphers(ssl, buf, sizeof(buf))) {
      DBUG_PRINT("info", ("shared_ciphers: '%s'", buf));
    } else
      DBUG_PRINT("info", ("no shared ciphers!"));
  }
#endif

  DBUG_RETURN(0);
}

int sslaccept(struct st_VioSSLFd *ptr, Vio *vio, long timeout,
              unsigned long *ssl_errno_holder) {
  DBUG_ENTER("sslaccept");
  int ret = ssl_do(ptr, vio, timeout, SSL_accept, ssl_errno_holder, nullptr);
  DBUG_RETURN(ret);
}

int sslconnect(struct st_VioSSLFd *ptr, Vio *vio, long timeout,
               unsigned long *ssl_errno_holder, SSL **ssl) {
  DBUG_ENTER("sslconnect");
  int ret = ssl_do(ptr, vio, timeout, SSL_connect, ssl_errno_holder, ssl);
  DBUG_RETURN(ret);
}

bool vio_ssl_has_data(Vio *vio) {
  return SSL_pending(static_cast<SSL *>(vio->ssl_arg)) > 0 ? true : false;
}

#endif /* HAVE_OPENSSL */