sendmail/src/sfsasl.c

	sfsasl.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * Copyright (c) 1999-2004 Sendmail, Inc. and its suppliers.
 *  All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sm/gen.h>
SM_RCSID("@(#)$Id: sfsasl.c,v 8.101 2004/12/15 22:45:55 ca Exp $")
#include <stdlib.h>
#include <sendmail.h>
#include <errno.h>

/* allow to disable error handling code just in case... */
#ifndef DEAL_WITH_ERROR_SSL
# define DEAL_WITH_ERROR_SSL    1
#endif /* ! DEAL_WITH_ERROR_SSL */

#if SASL
# include "sfsasl.h"

/* Structure used by the "sasl" file type */
struct sasl_obj
{
    SM_FILE_T *fp;
    sasl_conn_t *conn;
};

struct sasl_info
{
    SM_FILE_T *fp;
    sasl_conn_t *conn;
};

/*
**  SASL_GETINFO - returns requested information about a "sasl" file
**        descriptor.
**
**  Parameters:
**      fp -- the file descriptor
**      what -- the type of information requested
**      valp -- the thang to return the information in
**
**  Returns:
**      -1 for unknown requests
**      >=0 on success with valp filled in (if possible).
*/

static int sasl_getinfo __P((SM_FILE_T *, int, void *));

static int
sasl_getinfo(fp, what, valp)
    SM_FILE_T *fp;
    int what;
    void *valp;
{
    struct sasl_obj *so = (struct sasl_obj *) fp->f_cookie;

    switch (what)
    {
      case SM_IO_WHAT_FD:
        if (so->fp == NULL)
            return -1;
        return so->fp->f_file; /* for stdio fileno() compatability */

      case SM_IO_IS_READABLE:
        if (so->fp == NULL)
            return 0;

        /* get info from underlying file */
        return sm_io_getinfo(so->fp, what, valp);

      default:
        return -1;
    }
}

/*
**  SASL_OPEN -- creates the sasl specific information for opening a
**      file of the sasl type.
**
**  Parameters:
**      fp -- the file pointer associated with the new open
**      info -- contains the sasl connection information pointer and
**          the original SM_FILE_T that holds the open
**      flags -- ignored
**      rpool -- ignored
**
**  Returns:
**      0 on success
*/

static int sasl_open __P((SM_FILE_T *, const void *, int, const void *));

/* ARGSUSED2 */
static int
sasl_open(fp, info, flags, rpool)
    SM_FILE_T *fp;
    const void *info;
    int flags;
    const void *rpool;
{
    struct sasl_obj *so;
    struct sasl_info *si = (struct sasl_info *) info;

    so = (struct sasl_obj *) sm_malloc(sizeof(struct sasl_obj));
    if (so == NULL)
    {
        errno = ENOMEM;
        return -1;
    }
    so->fp = si->fp;
    so->conn = si->conn;

    /*
    **  The underlying 'fp' is set to SM_IO_NOW so that the entire
    **  encoded string is written in one chunk. Otherwise there is
    **  the possibility that it may appear illegal, bogus or
    **  mangled to the other side of the connection.
    **  We will read or write through 'fp' since it is the opaque
    **  connection for the communications. We need to treat it this
    **  way in case the encoded string is to be sent down a TLS
    **  connection rather than, say, sm_io's stdio.
    */

    (void) sm_io_setvbuf(so->fp, SM_TIME_DEFAULT, NULL, SM_IO_NOW, 0);
    fp->f_cookie = so;
    return 0;
}

/*
**  SASL_CLOSE -- close the sasl specific parts of the sasl file pointer
**
**  Parameters:
**      fp -- the file pointer to close
**
**  Returns:
**      0 on success
*/

static int sasl_close __P((SM_FILE_T *));

static int
sasl_close(fp)
    SM_FILE_T *fp;
{
    struct sasl_obj *so;

    so = (struct sasl_obj *) fp->f_cookie;
    if (so == NULL)
        return 0;
    if (so->fp != NULL)
    {
        sm_io_close(so->fp, SM_TIME_DEFAULT);
        so->fp = NULL;
    }
    sm_free(so);
    so = NULL;
    return 0;
}

/* how to deallocate a buffer allocated by SASL */
extern void sm_sasl_free __P((void *));
#  define SASL_DEALLOC(b)   sm_sasl_free(b)

/*
**  SASL_READ -- read encrypted information and decrypt it for the caller
**
**  Parameters:
**      fp -- the file pointer
**      buf -- the location to place the decrypted information
**      size -- the number of bytes to read after decryption
**
**  Results:
**      -1 on error
**      otherwise the number of bytes read
*/

static ssize_t sasl_read __P((SM_FILE_T *, char *, size_t));

static ssize_t
sasl_read(fp, buf, size)
    SM_FILE_T *fp;
    char *buf;
    size_t size;
{
    int result;
    ssize_t len;
# if SASL >= 20000
    static const char *outbuf = NULL;
# else /* SASL >= 20000 */
    static char *outbuf = NULL;
# endif /* SASL >= 20000 */
    static unsigned int outlen = 0;
    static unsigned int offset = 0;
    struct sasl_obj *so = (struct sasl_obj *) fp->f_cookie;

    /*
    **  sasl_decode() may require more data than a single read() returns.
    **  Hence we have to put a loop around the decoding.
    **  This also requires that we may have to split up the returned
    **  data since it might be larger than the allowed size.
    **  Therefore we use a static pointer and return portions of it
    **  if necessary.
    **  XXX Note: This function is not thread-safe nor can it be used
    **  on more than one file. A correct implementation would store
    **  this data in fp->f_cookie.
    */

# if SASL >= 20000
    while (outlen == 0)
# else /* SASL >= 20000 */
    while (outbuf == NULL && outlen == 0)
# endif /* SASL >= 20000 */
    {
        len = sm_io_read(so->fp, SM_TIME_DEFAULT, buf, size);
        if (len <= 0)
            return len;
        result = sasl_decode(so->conn, buf,
                     (unsigned int) len, &outbuf, &outlen);
        if (result != SASL_OK)
        {
            outbuf = NULL;
            offset = 0;
            outlen = 0;
            return -1;
        }
    }

    if (outbuf == NULL)
    {
        /* be paranoid: outbuf == NULL but outlen != 0 */
        syserr("@sasl_read failure: outbuf == NULL but outlen != 0");
        /* NOTREACHED */
    }
    if (outlen - offset > size)
    {
        /* return another part of the buffer */
        (void) memcpy(buf, outbuf + offset, size);
        offset += size;
        len = size;
    }
    else
    {
        /* return the rest of the buffer */
        len = outlen - offset;
        (void) memcpy(buf, outbuf + offset, (size_t) len);
# if SASL < 20000
        SASL_DEALLOC(outbuf);
# endif /* SASL < 20000 */
        outbuf = NULL;
        offset = 0;
        outlen = 0;
    }
    return len;
}

/*
**  SASL_WRITE -- write information out after encrypting it
**
**  Parameters:
**      fp -- the file pointer
**      buf -- holds the data to be encrypted and written
**      size -- the number of bytes to have encrypted and written
**
**  Returns:
**      -1 on error
**      otherwise number of bytes written
*/

static ssize_t sasl_write __P((SM_FILE_T *, const char *, size_t));

static ssize_t
sasl_write(fp, buf, size)
    SM_FILE_T *fp;
    const char *buf;
    size_t size;
{
    int result;
# if SASL >= 20000
    const char *outbuf;
# else /* SASL >= 20000 */
    char *outbuf;
# endif /* SASL >= 20000 */
    unsigned int outlen, *maxencode;
    size_t ret = 0, total = 0;
    struct sasl_obj *so = (struct sasl_obj *) fp->f_cookie;

    /*
    **  Fetch the maximum input buffer size for sasl_encode().
    **  This can be less than the size set in attemptauth()
    **  due to a negotation with the other side, e.g.,
    **  Cyrus IMAP lmtp program sets maxbuf=4096,
    **  digestmd5 substracts 25 and hence we'll get 4071
    **  instead of 8192 (MAXOUTLEN).
    **  Hack (for now): simply reduce the size, callers are (must be)
    **  able to deal with that and invoke sasl_write() again with
    **  the rest of the data.
    **  Note: it would be better to store this value in the context
    **  after the negotiation.
    */

    result = sasl_getprop(so->conn, SASL_MAXOUTBUF,
                             (const void **) &maxencode);
    if (result == SASL_OK && size > *maxencode && *maxencode > 0)
        size = *maxencode;

    result = sasl_encode(so->conn, buf,
                 (unsigned int) size, &outbuf, &outlen);

    if (result != SASL_OK)
        return -1;

    if (outbuf != NULL)
    {
        while (outlen > 0)
        {
            /* XXX result == 0? */
            ret = sm_io_write(so->fp, SM_TIME_DEFAULT,
                      &outbuf[total], outlen);
            if (ret <= 0)
                return ret;
            outlen -= ret;
            total += ret;
        }
# if SASL < 20000
        SASL_DEALLOC(outbuf);
# endif /* SASL < 20000 */
    }
    return size;
}

/*
**  SFDCSASL -- create sasl file type and open in and out file pointers
**         for sendmail to read from and write to.
**
**  Parameters:
**      fin -- the sm_io file encrypted data to be read from
**      fout -- the sm_io file encrypted data to be writen to
**      conn -- the sasl connection pointer
**
**  Returns:
**      -1 on error
**      0 on success
**
**  Side effects:
**      The arguments "fin" and "fout" are replaced with the new
**      SM_FILE_T pointers.
*/

int
sfdcsasl(fin, fout, conn)
    SM_FILE_T **fin;
    SM_FILE_T **fout;
    sasl_conn_t *conn;
{
    SM_FILE_T *newin, *newout;
    SM_FILE_T  SM_IO_SET_TYPE(sasl_vector, "sasl", sasl_open, sasl_close,
        sasl_read, sasl_write, NULL, sasl_getinfo, NULL,
        SM_TIME_FOREVER);
    struct sasl_info info;

    if (conn == NULL)
    {
        /* no need to do anything */
        return 0;
    }

    SM_IO_INIT_TYPE(sasl_vector, "sasl", sasl_open, sasl_close,
        sasl_read, sasl_write, NULL, sasl_getinfo, NULL,
        SM_TIME_FOREVER);
    info.fp = *fin;
    info.conn = conn;
    newin = sm_io_open(&sasl_vector, SM_TIME_DEFAULT, &info,
            SM_IO_RDONLY_B, NULL);

    if (newin == NULL)
        return -1;

    info.fp = *fout;
    info.conn = conn;
    newout = sm_io_open(&sasl_vector, SM_TIME_DEFAULT, &info,
            SM_IO_WRONLY_B, NULL);

    if (newout == NULL)
    {
        (void) sm_io_close(newin, SM_TIME_DEFAULT);
        return -1;
    }
    sm_io_automode(newin, newout);

    *fin = newin;
    *fout = newout;
    return 0;
}
#endif /* SASL */

#if STARTTLS
# include "sfsasl.h"
#  include <openssl/err.h>

/* Structure used by the "tls" file type */
struct tls_obj
{
    SM_FILE_T *fp;
    SSL *con;
};

struct tls_info
{
    SM_FILE_T *fp;
    SSL *con;
};

/*
**  TLS_GETINFO - returns requested information about a "tls" file
**       descriptor.
**
**  Parameters:
**      fp -- the file descriptor
**      what -- the type of information requested
**      valp -- the thang to return the information in (unused)
**
**  Returns:
**      -1 for unknown requests
**      >=0 on success with valp filled in (if possible).
*/

static int tls_getinfo __P((SM_FILE_T *, int, void *));

/* ARGSUSED2 */
static int
tls_getinfo(fp, what, valp)
    SM_FILE_T *fp;
    int what;
    void *valp;
{
    struct tls_obj *so = (struct tls_obj *) fp->f_cookie;

    switch (what)
    {
      case SM_IO_WHAT_FD:
        if (so->fp == NULL)
            return -1;
        return so->fp->f_file; /* for stdio fileno() compatability */

      case SM_IO_IS_READABLE:
        return SSL_pending(so->con) > 0;

      default:
        return -1;
    }
}

/*
**  TLS_OPEN -- creates the tls specific information for opening a
**         file of the tls type.
**
**  Parameters:
**      fp -- the file pointer associated with the new open
**      info -- the sm_io file pointer holding the open and the
**          TLS encryption connection to be read from or written to
**      flags -- ignored
**      rpool -- ignored
**
**  Returns:
**      0 on success
*/

static int tls_open __P((SM_FILE_T *, const void *, int, const void *));

/* ARGSUSED2 */
static int
tls_open(fp, info, flags, rpool)
    SM_FILE_T *fp;
    const void *info;
    int flags;
    const void *rpool;
{
    struct tls_obj *so;
    struct tls_info *ti = (struct tls_info *) info;

    so = (struct tls_obj *) sm_malloc(sizeof(struct tls_obj));
    if (so == NULL)
    {
        errno = ENOMEM;
        return -1;
    }
    so->fp = ti->fp;
    so->con = ti->con;

    /*
    **  We try to get the "raw" file descriptor that TLS uses to
    **  do the actual read/write with. This is to allow us control
    **  over the file descriptor being a blocking or non-blocking type.
    **  Under the covers TLS handles the change and this allows us
    **  to do timeouts with sm_io.
    */

    fp->f_file = sm_io_getinfo(so->fp, SM_IO_WHAT_FD, NULL);
    (void) sm_io_setvbuf(so->fp, SM_TIME_DEFAULT, NULL, SM_IO_NOW, 0);
    fp->f_cookie = so;
    return 0;
}

/*
**  TLS_CLOSE -- close the tls specific parts of the tls file pointer
**
**  Parameters:
**      fp -- the file pointer to close
**
**  Returns:
**      0 on success
*/

static int tls_close __P((SM_FILE_T *));

static int
tls_close(fp)
    SM_FILE_T *fp;
{
    struct tls_obj *so;

    so = (struct tls_obj *) fp->f_cookie;
    if (so == NULL)
        return 0;
    if (so->fp != NULL)
    {
        sm_io_close(so->fp, SM_TIME_DEFAULT);
        so->fp = NULL;
    }
    sm_free(so);
    so = NULL;
    return 0;
}

/* maximum number of retries for TLS related I/O due to handshakes */
# define MAX_TLS_IOS    4

/*
**  TLS_READ -- read secured information for the caller
**
**  Parameters:
**      fp -- the file pointer
**      buf -- the location to place the data
**      size -- the number of bytes to read from connection
**
**  Results:
**      -1 on error
**      otherwise the number of bytes read
*/

static ssize_t tls_read __P((SM_FILE_T *, char *, size_t));

static ssize_t
tls_read(fp, buf, size)
    SM_FILE_T *fp;
    char *buf;
    size_t size;
{
    int r;
    static int again = MAX_TLS_IOS;
    struct tls_obj *so = (struct tls_obj *) fp->f_cookie;
    char *err;

    r = SSL_read(so->con, (char *) buf, size);

    if (r > 0)
    {
        again = MAX_TLS_IOS;
        return r;
    }

    err = NULL;
    switch (SSL_get_error(so->con, r))
    {
      case SSL_ERROR_NONE:
      case SSL_ERROR_ZERO_RETURN:
        again = MAX_TLS_IOS;
        break;
      case SSL_ERROR_WANT_WRITE:
        if (--again <= 0)
            err = "read W BLOCK";
        else
            errno = EAGAIN;
        break;
      case SSL_ERROR_WANT_READ:
        if (--again <= 0)
            err = "read R BLOCK";
        else
            errno = EAGAIN;
        break;
      case SSL_ERROR_WANT_X509_LOOKUP:
        err = "write X BLOCK";
        break;
      case SSL_ERROR_SYSCALL:
        if (r == 0 && errno == 0) /* out of protocol EOF found */
            break;
        err = "syscall error";
/*
        get_last_socket_error());
*/
        break;
      case SSL_ERROR_SSL:
#if DEAL_WITH_ERROR_SSL
        if (r == 0 && errno == 0) /* out of protocol EOF found */
            break;
#endif /* DEAL_WITH_ERROR_SSL */
        err = "generic SSL error";
        if (LogLevel > 9)
            tlslogerr("read");

#if DEAL_WITH_ERROR_SSL
        /* avoid repeated calls? */
        if (r == 0)
            r = -1;
#endif /* DEAL_WITH_ERROR_SSL */
        break;
    }
    if (err != NULL)
    {
        int save_errno;

        save_errno = (errno == 0) ? EIO : errno;
        again = MAX_TLS_IOS;
        if (LogLevel > 9)
            sm_syslog(LOG_WARNING, NOQID,
                  "STARTTLS: read error=%s (%d), errno=%d, get_error=%s",
                  err, r, errno,
                  ERR_error_string(ERR_get_error(), NULL));
        else if (LogLevel > 7)
            sm_syslog(LOG_WARNING, NOQID,
                  "STARTTLS: read error=%s (%d)", err, r);
        errno = save_errno;
    }
    return r;
}

/*
**  TLS_WRITE -- write information out through secure connection
**
**  Parameters:
**      fp -- the file pointer
**      buf -- holds the data to be securely written
**      size -- the number of bytes to write
**
**  Returns:
**      -1 on error
**      otherwise number of bytes written
*/

static ssize_t tls_write __P((SM_FILE_T *, const char *, size_t));

static ssize_t
tls_write(fp, buf, size)
    SM_FILE_T *fp;
    const char *buf;
    size_t size;
{
    int r;
    static int again = MAX_TLS_IOS;
    struct tls_obj *so = (struct tls_obj *) fp->f_cookie;
    char *err;

    r = SSL_write(so->con, (char *) buf, size);

    if (r > 0)
    {
        again = MAX_TLS_IOS;
        return r;
    }
    err = NULL;
    switch (SSL_get_error(so->con, r))
    {
      case SSL_ERROR_NONE:
      case SSL_ERROR_ZERO_RETURN:
        again = MAX_TLS_IOS;
        break;
      case SSL_ERROR_WANT_WRITE:
        if (--again <= 0)
            err = "write W BLOCK";
        else
            errno = EAGAIN;
        break;
      case SSL_ERROR_WANT_READ:
        if (--again <= 0)
            err = "write R BLOCK";
        else
            errno = EAGAIN;
        break;
      case SSL_ERROR_WANT_X509_LOOKUP:
        err = "write X BLOCK";
        break;
      case SSL_ERROR_SYSCALL:
        if (r == 0 && errno == 0) /* out of protocol EOF found */
            break;
        err = "syscall error";
/*
        get_last_socket_error());
*/
        break;
      case SSL_ERROR_SSL:
        err = "generic SSL error";
/*
        ERR_GET_REASON(ERR_peek_error()));
*/
        if (LogLevel > 9)
            tlslogerr("write");

#if DEAL_WITH_ERROR_SSL
        /* avoid repeated calls? */
        if (r == 0)
            r = -1;
#endif /* DEAL_WITH_ERROR_SSL */
        break;
    }
    if (err != NULL)
    {
        int save_errno;

        save_errno = (errno == 0) ? EIO : errno;
        again = MAX_TLS_IOS;
        if (LogLevel > 9)
            sm_syslog(LOG_WARNING, NOQID,
                  "STARTTLS: write error=%s (%d), errno=%d, get_error=%s",
                  err, r, errno,
                  ERR_error_string(ERR_get_error(), NULL));
        else if (LogLevel > 7)
            sm_syslog(LOG_WARNING, NOQID,
                  "STARTTLS: write error=%s (%d)", err, r);
        errno = save_errno;
    }
    return r;
}

/*
**  SFDCTLS -- create tls file type and open in and out file pointers
**        for sendmail to read from and write to.
**
**  Parameters:
**      fin -- data input source being replaced
**      fout -- data output source being replaced
**      con -- the tls connection pointer
**
**  Returns:
**      -1 on error
**      0 on success
**
**  Side effects:
**      The arguments "fin" and "fout" are replaced with the new
**      SM_FILE_T pointers.
**      The original "fin" and "fout" are preserved in the tls file
**      type but are not actually used because of the design of TLS.
*/

int
sfdctls(fin, fout, con)
    SM_FILE_T **fin;
    SM_FILE_T **fout;
    SSL *con;
{
    SM_FILE_T *tlsin, *tlsout;
    SM_FILE_T SM_IO_SET_TYPE(tls_vector, "tls", tls_open, tls_close,
        tls_read, tls_write, NULL, tls_getinfo, NULL,
        SM_TIME_FOREVER);
    struct tls_info info;

    SM_ASSERT(con != NULL);

    SM_IO_INIT_TYPE(tls_vector, "tls", tls_open, tls_close,
        tls_read, tls_write, NULL, tls_getinfo, NULL,
        SM_TIME_FOREVER);
    info.fp = *fin;
    info.con = con;
    tlsin = sm_io_open(&tls_vector, SM_TIME_DEFAULT, &info, SM_IO_RDONLY_B,
               NULL);
    if (tlsin == NULL)
        return -1;

    info.fp = *fout;
    tlsout = sm_io_open(&tls_vector, SM_TIME_DEFAULT, &info, SM_IO_WRONLY_B,
                NULL);
    if (tlsout == NULL)
    {
        (void) sm_io_close(tlsin, SM_TIME_DEFAULT);
        return -1;
    }
    sm_io_automode(tlsin, tlsout);

    *fin = tlsin;
    *fout = tlsout;
    return 0;
}
#endif /* STARTTLS */