gnupg/g10/call-agent.c

/* call-agent.c - divert operations to the agent
 * Copyright (C) 2001, 2002, 2003, 2006, 2007 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h> 
#include <time.h>
#include <assert.h>
#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif
#include <assuan.h>

#include "gpg.h"
#include "util.h"
#include "membuf.h"
#include "options.h"
#include "i18n.h"
#include "asshelp.h"
#include "call-agent.h"

#ifndef DBG_ASSUAN
# define DBG_ASSUAN 1
#endif

static assuan_context_t agent_ctx = NULL;

struct cipher_parm_s 
{
  assuan_context_t ctx;
  const char *ciphertext;
  size_t ciphertextlen;
};

struct writekey_parm_s
{
  assuan_context_t ctx;
  const unsigned char *keydata;
  size_t keydatalen;
};

struct genkey_parm_s 
{
  assuan_context_t ctx;
  const char *sexp;
  size_t sexplen;
};



/* Try to connect to the agent via socket or fork it off and work by
   pipes.  Handle the server's initial greeting */
static int
start_agent (void)
{
  if (agent_ctx)
    return 0; /* Fixme: We need a context for each thread or serialize
                 the access to the agent. */

  return start_new_gpg_agent (&agent_ctx,
                              GPG_ERR_SOURCE_DEFAULT,
                              opt.homedir,
                              opt.agent_program,
                              opt.display, opt.ttyname, opt.ttytype,
                              opt.lc_ctype, opt.lc_messages,
                              opt.verbose, DBG_ASSUAN,
                              NULL, NULL);
}


/* Return a new malloced string by unescaping the string S.  Escaping
   is percent escaping and '+'/space mapping.  A binary nul will
   silently be replaced by a 0xFF.  Function returns NULL to indicate
   an out of memory status. */
static char *
unescape_status_string (const unsigned char *s)
{
  char *buffer, *d;

  buffer = d = xtrymalloc (strlen (s)+1);
  if (!buffer)
    return NULL;
  while (*s)
    {
      if (*s == '%' && s[1] && s[2])
        { 
          s++;
          *d = xtoi_2 (s);
          if (!*d)
            *d = '\xff';
          d++;
          s += 2;
        }
      else if (*s == '+')
        {
          *d++ = ' ';
          s++;
        }
      else
        *d++ = *s++;
    }
  *d = 0; 
  return buffer;
}

/* Copy the text ATEXT into the buffer P and do plus '+' and percent
   escaping.  Note that the provided buffer needs to be 3 times the
   size of ATEXT plus 1.  Returns a pointer to the leading Nul in P. */
static char *
percent_plus_escape (char *p, const char *atext)
{
  const unsigned char *s;

  for (s=atext; *s; s++)
    {
      if (*s < ' ' || *s == '+')
        {
          sprintf (p, "%%%02X", *s);
          p += 3;
        }
      else if (*s == ' ')
        *p++ = '+';
      else
        *p++ = *s;
    }
  *p = 0;
  return p;
}

/* Take a 20 byte hexencoded string and put it into the the provided
   20 byte buffer FPR in binary format. */
static int
unhexify_fpr (const char *hexstr, unsigned char *fpr)
{
  const char *s;
  int n;

  for (s=hexstr, n=0; hexdigitp (s); s++, n++)
    ;
  if (*s || (n != 40))
    return 0; /* no fingerprint (invalid or wrong length). */
  n /= 2;
  for (s=hexstr, n=0; *s; s += 2, n++)
    fpr[n] = xtoi_2 (s);
  return 1; /* okay */
}

/* Take the serial number from LINE and return it verbatim in a newly
   allocated string.  We make sure that only hex characters are
   returned. */
static char *
store_serialno (const char *line)
{
  const char *s;
  char *p;

  for (s=line; hexdigitp (s); s++)
    ;
  p = xtrymalloc (s + 1 - line);
  if (p)
    {
      memcpy (p, line, s-line);
      p[s-line] = 0;
    }
  return p;
}



/* Release the card info structure INFO. */
void
agent_release_card_info (struct agent_card_info_s *info)
{
  if (!info)
    return;

  xfree (info->serialno); info->serialno = NULL;
  xfree (info->disp_name); info->disp_name = NULL;
  xfree (info->disp_lang); info->disp_lang = NULL;
  xfree (info->pubkey_url); info->pubkey_url = NULL;
  xfree (info->login_data); info->login_data = NULL;
  info->cafpr1valid = info->cafpr2valid = info->cafpr3valid = 0;
  info->fpr1valid = info->fpr2valid = info->fpr3valid = 0;
}

static int
learn_status_cb (void *opaque, const char *line)
{
  struct agent_card_info_s *parm = opaque;
  const char *keyword = line;
  int keywordlen;
  int i;

  for (keywordlen=0; *line && !spacep (line); line++, keywordlen++)
    ;
  while (spacep (line))
    line++;

  if (keywordlen == 8 && !memcmp (keyword, "SERIALNO", keywordlen))
    {
      xfree (parm->serialno);
      parm->serialno = store_serialno (line);
    }
  else if (keywordlen == 9 && !memcmp (keyword, "DISP-NAME", keywordlen))
    {
      xfree (parm->disp_name);
      parm->disp_name = unescape_status_string (line);
    }
  else if (keywordlen == 9 && !memcmp (keyword, "DISP-LANG", keywordlen))
    {
      xfree (parm->disp_lang);
      parm->disp_lang = unescape_status_string (line);
    }
  else if (keywordlen == 8 && !memcmp (keyword, "DISP-SEX", keywordlen))
    {
      parm->disp_sex = *line == '1'? 1 : *line == '2' ? 2: 0;
    }
  else if (keywordlen == 10 && !memcmp (keyword, "PUBKEY-URL", keywordlen))
    {
      xfree (parm->pubkey_url);
      parm->pubkey_url = unescape_status_string (line);
    }
  else if (keywordlen == 10 && !memcmp (keyword, "LOGIN-DATA", keywordlen))
    {
      xfree (parm->login_data);
      parm->login_data = unescape_status_string (line);
    }
  else if (keywordlen == 11 && !memcmp (keyword, "SIG-COUNTER", keywordlen))
    {
      parm->sig_counter = strtoul (line, NULL, 0);
    }
  else if (keywordlen == 10 && !memcmp (keyword, "CHV-STATUS", keywordlen))
    {
      char *p, *buf;

      buf = p = unescape_status_string (line);
      if (buf)
        {
          while (spacep (p))
            p++;
          parm->chv1_cached = atoi (p);
          while (*p && !spacep (p))
            p++;
          while (spacep (p))
            p++;
          for (i=0; *p && i < 3; i++)
            {
              parm->chvmaxlen[i] = atoi (p);
              while (*p && !spacep (p))
                p++;
              while (spacep (p))
                p++;
            }
          for (i=0; *p && i < 3; i++)
            {
              parm->chvretry[i] = atoi (p);
              while (*p && !spacep (p))
                p++;
              while (spacep (p))
                p++;
            }
          xfree (buf);
        }
    }
  else if (keywordlen == 7 && !memcmp (keyword, "KEY-FPR", keywordlen))
    {
      int no = atoi (line);
      while (*line && !spacep (line))
        line++;
      while (spacep (line))
        line++;
      if (no == 1)
        parm->fpr1valid = unhexify_fpr (line, parm->fpr1);
      else if (no == 2)
        parm->fpr2valid = unhexify_fpr (line, parm->fpr2);
      else if (no == 3)
        parm->fpr3valid = unhexify_fpr (line, parm->fpr3);
    }
  else if (keywordlen == 6 && !memcmp (keyword, "CA-FPR", keywordlen))
    {
      int no = atoi (line);
      while (*line && !spacep (line))
        line++;
      while (spacep (line))
        line++;
      if (no == 1)
        parm->cafpr1valid = unhexify_fpr (line, parm->cafpr1);
      else if (no == 2)
        parm->cafpr2valid = unhexify_fpr (line, parm->cafpr2);
      else if (no == 3)
        parm->cafpr3valid = unhexify_fpr (line, parm->cafpr3);
    }
  
  return 0;
}

/* Call the agent to learn about a smartcard */
int
agent_learn (struct agent_card_info_s *info)
{
  int rc;

  rc = start_agent ();
  if (rc)
    return rc;

  memset (info, 0, sizeof *info);
  rc = assuan_transact (agent_ctx, "LEARN --send",
                        NULL, NULL, NULL, NULL,
                        learn_status_cb, info);
  
  return rc;
}

/* Call the agent to retrieve a data object.  This function returns
   the data in the same structure as used by the learn command.  It is
   allowed to update such a structure using this commmand. */
int
agent_scd_getattr (const char *name, struct agent_card_info_s *info)
{
  int rc;
  char line[ASSUAN_LINELENGTH];

  if (!*name)
    return gpg_error (GPG_ERR_INV_VALUE);

  /* We assume that NAME does not need escaping. */
  if (12 + strlen (name) > DIM(line)-1)
    return gpg_error (GPG_ERR_TOO_LARGE);
  stpcpy (stpcpy (line, "SCD GETATTR "), name); 

  rc = start_agent ();
  if (rc)
    return rc;

  rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL,
                        learn_status_cb, info);
  
  return rc;
}


/* Send an setattr command to the SCdaemon.  SERIALNO is not actually
   used here but required by gpg 1.4's implementation of this code in
   cardglue.c. */
int
agent_scd_setattr (const char *name,
                   const unsigned char *value, size_t valuelen,
                   const char *serialno)
{
  int rc;
  char line[ASSUAN_LINELENGTH];
  char *p;

  if (!*name || !valuelen)
    return gpg_error (GPG_ERR_INV_VALUE);

  /* We assume that NAME does not need escaping. */
  if (12 + strlen (name) > DIM(line)-1)
    return gpg_error (GPG_ERR_TOO_LARGE);
      
  p = stpcpy (stpcpy (line, "SCD SETATTR "), name); 
  *p++ = ' ';
  for (; valuelen; value++, valuelen--)
    {
      if (p >= line + DIM(line)-5 )
        return gpg_error (GPG_ERR_TOO_LARGE);
      if (*value < ' ' || *value == '+' || *value == '%')
        {
          sprintf (p, "%%%02X", *value);
          p += 3;
        }
      else if (*value == ' ')
        *p++ = '+';
      else
        *p++ = *value;
    }
  *p = 0;

  rc = start_agent ();
  if (rc)
    return rc;

  rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
  return rc;
}



/* Handle a KEYDATA inquiry.  Note, we only send the data,
   assuan_transact takes care of flushing and writing the end */
static assuan_error_t
inq_writekey_parms (void *opaque, const char *keyword)
{
  struct writekey_parm_s *parm = opaque; 

  return assuan_send_data (parm->ctx, parm->keydata, parm->keydatalen);
}


/* Send a WRITEKEY command to the SCdaemon. */
int 
agent_scd_writekey (int keyno, const char *serialno,
                    const unsigned char *keydata, size_t keydatalen)
{
  int rc;
  char line[ASSUAN_LINELENGTH];
  struct writekey_parm_s parms;

  rc = start_agent ();
  if (rc)
    return rc;

  memset (&parms, 0, sizeof parms);

  snprintf (line, DIM(line)-1, "SCD WRITEKEY --force OPENPGP.%d", keyno);
  line[DIM(line)-1] = 0;
  parms.ctx = agent_ctx;
  parms.keydata = keydata;
  parms.keydatalen = keydatalen;
  
  rc = assuan_transact (agent_ctx, line, NULL, NULL,
                        inq_writekey_parms, &parms, NULL, NULL);

  return rc;
}




/* Status callback for the SCD GENKEY command. */
static int
scd_genkey_cb (void *opaque, const char *line)
{
  struct agent_card_genkey_s *parm = opaque;
  const char *keyword = line;
  int keywordlen;
  gpg_error_t rc;

  log_debug ("got status line `%s'\n", line);
  for (keywordlen=0; *line && !spacep (line); line++, keywordlen++)
    ;
  while (spacep (line))
    line++;

  if (keywordlen == 7 && !memcmp (keyword, "KEY-FPR", keywordlen))
    {
      parm->fprvalid = unhexify_fpr (line, parm->fpr);
    }
  if (keywordlen == 8 && !memcmp (keyword, "KEY-DATA", keywordlen))
    {
      gcry_mpi_t a;
      const char *name = line;

      while (*line && !spacep (line))
        line++;
      while (spacep (line))
        line++;

      rc = gcry_mpi_scan (&a, GCRYMPI_FMT_HEX, line, 0, NULL);
      if (rc)
        log_error ("error parsing received key data: %s\n", gpg_strerror (rc));
      else if (*name == 'n' && spacep (name+1))
        parm->n = a;
      else if (*name == 'e' && spacep (name+1))
        parm->e = a;
      else
        {
          log_info ("unknown parameter name in received key data\n");
          gcry_mpi_release (a);
        }
    }
  else if (keywordlen == 14 && !memcmp (keyword,"KEY-CREATED-AT", keywordlen))
    {
      parm->created_at = (u32)strtoul (line, NULL, 10);
    }

  return 0;
}

/* Send a GENKEY command to the SCdaemon.  SERIALNO is not used in
   this implementation.  If CREATEDATE has been given, it will be
   passed to SCDAEMON so that the key can be created with this
   timestamp; note the user needs to use the returned timestamp as old
   versions of scddaemon don't support this option.  */
int
agent_scd_genkey (struct agent_card_genkey_s *info, int keyno, int force,
                  const char *serialno, u32 createtime)
{
  int rc;
  char line[ASSUAN_LINELENGTH];
  gnupg_isotime_t tbuf;

  rc = start_agent ();
  if (rc)
    return rc;

  if (createtime)
    epoch2isotime (tbuf, createtime);
  else
    *tbuf = 0;

  memset (info, 0, sizeof *info);
  snprintf (line, DIM(line)-1, "SCD GENKEY %s%s %s %d",
            *tbuf? "--timestamp=":"", tbuf,
            force? "--force":"", 
            keyno);
  line[DIM(line)-1] = 0;

  memset (info, 0, sizeof *info);
  rc = assuan_transact (agent_ctx, line,
                        NULL, NULL, NULL, NULL,
                        scd_genkey_cb, info);
  
  return rc;
}


static int
membuf_data_cb (void *opaque, const void *buffer, size_t length)
{
  membuf_t *data = opaque;

  if (buffer)
    put_membuf (data, buffer, length);
  return 0;
}
  
/* Send a sign command to the scdaemon via gpg-agent's pass thru
   mechanism. */
int
agent_scd_pksign (const char *serialno, int hashalgo,
                  const unsigned char *indata, size_t indatalen,
                  unsigned char **r_buf, size_t *r_buflen)
{
  int rc, i;
  char *p, line[ASSUAN_LINELENGTH];
  membuf_t data;
  size_t len;

  /* Note, hashalgo is not yet used but hardwired to SHA1 in SCdaemon. */

  *r_buf = NULL;
  *r_buflen = 0;

  rc = start_agent ();
  if (rc)
    return rc;

  if (indatalen*2 + 50 > DIM(line))
    return gpg_error (GPG_ERR_GENERAL);

  sprintf (line, "SCD SETDATA ");
  p = line + strlen (line);
  for (i=0; i < indatalen ; i++, p += 2 )
    sprintf (p, "%02X", indata[i]);
  rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
  if (rc)
    return rc;

  init_membuf (&data, 1024);
#if 0
  if (!hashalgo) /* Temporary test hack. */
    snprintf (line, DIM(line)-1, "SCD PKAUTH %s", serialno);
  else
#endif
    snprintf (line, DIM(line)-1, "SCD PKSIGN %s%s",
              hashalgo == GCRY_MD_RMD160? "--hash=rmd160 " : "",
              serialno);
  line[DIM(line)-1] = 0;
  rc = assuan_transact (agent_ctx, line, membuf_data_cb, &data,
                        NULL, NULL, NULL, NULL);
  if (rc)
    {
      xfree (get_membuf (&data, &len));
      return rc;
    }
  *r_buf = get_membuf (&data, r_buflen);

  return 0;
}


/* Decrypt INDATA of length INDATALEN using the card identified by
   SERIALNO.  Return the plaintext in a nwly allocated buffer stored
   at the address of R_BUF. 

   Note, we currently support only RSA or more exactly algorithms
   taking one input data element. */
int
agent_scd_pkdecrypt (const char *serialno,
                     const unsigned char *indata, size_t indatalen,
                     unsigned char **r_buf, size_t *r_buflen)
{
  int rc, i;
  char *p, line[ASSUAN_LINELENGTH];
  membuf_t data;
  size_t len;

  *r_buf = NULL;
  rc = start_agent ();
  if (rc)
    return rc;

  /* FIXME: use secure memory where appropriate */
  if (indatalen*2 + 50 > DIM(line))
    return gpg_error (GPG_ERR_GENERAL);

  sprintf (line, "SCD SETDATA ");
  p = line + strlen (line);
  for (i=0; i < indatalen ; i++, p += 2 )
    sprintf (p, "%02X", indata[i]);
  rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
  if (rc)
    return rc;

  init_membuf (&data, 1024);
  snprintf (line, DIM(line)-1, "SCD PKDECRYPT %s", serialno);
  line[DIM(line)-1] = 0;
  rc = assuan_transact (agent_ctx, line,
                        membuf_data_cb, &data,
                        NULL, NULL, NULL, NULL);
  if (rc)
    {
      xfree (get_membuf (&data, &len));
      return rc;
    }
  *r_buf = get_membuf (&data, r_buflen);
  if (!*r_buf)
    return gpg_error (GPG_ERR_ENOMEM);

  return 0;
}


/* Change the PIN of an OpenPGP card or reset the retry counter.
   CHVNO 1: Change the PIN
         2: Same as 1
         3: Change the admin PIN
       101: Set a new PIN and reset the retry counter
       102: Same as 101
   SERIALNO is not used.
 */
int
agent_scd_change_pin (int chvno, const char *serialno)
{
  int rc;
  char line[ASSUAN_LINELENGTH];
  const char *reset = "";

  if (chvno >= 100)
    reset = "--reset";
  chvno %= 100;

  rc = start_agent ();
  if (rc)
    return rc;

  snprintf (line, DIM(line)-1, "SCD PASSWD %s %d", reset, chvno);
  line[DIM(line)-1] = 0;
  rc = assuan_transact (agent_ctx, line, NULL, NULL,
                        NULL, NULL, NULL, NULL);
  return rc;
}


/* Perform a CHECKPIN operation.  SERIALNO should be the serial
   number of the card - optionally followed by the fingerprint;
   however the fingerprint is ignored here. */
int
agent_scd_checkpin  (const char *serialno)
{
  int rc;
  char line[ASSUAN_LINELENGTH];

  rc = start_agent ();
  if (rc)
    return rc;

  snprintf (line, DIM(line)-1, "SCD CHECKPIN %s", serialno);
  line[DIM(line)-1] = 0;
  return assuan_transact (agent_ctx, line,
                          NULL, NULL,
                          NULL, NULL, NULL, NULL);
}


/* Dummy function, only used by the gpg 1.4 implementation. */
void
agent_clear_pin_cache (const char *sn)
{

}




/* Note: All strings shall be UTF-8. On success the caler needs to
   free the string stored at R_PASSPHRASE. On error NULL will be
   stored at R_PASSPHRASE and an appropriate fpf error code
   returned. */
gpg_error_t
agent_get_passphrase (const char *cache_id,
                      const char *err_msg,
                      const char *prompt,
                      const char *desc_msg,
                      char **r_passphrase)
{
  int rc;
  char *line, *p;
  char cmd[] = "GET_PASSPHRASE --data -- ";
  membuf_t data;

  *r_passphrase = NULL;

  rc = start_agent ();
  if (rc)
    return rc;

  /* We allocate 3 times the needed space for the texts so that
     there is enough space for escaping. */
  line = xtrymalloc ( strlen (cmd) + 1
                      + (cache_id? 3*strlen (cache_id): 1) + 1
                      + (err_msg?  3*strlen (err_msg): 1) + 1
                      + (prompt?   3*strlen (prompt): 1) + 1
                      + (desc_msg? 3*strlen (desc_msg): 1) + 1
                      + 1);
  if (!line)
    return gpg_error_from_syserror ();

  p = stpcpy (line, cmd);
  if (cache_id && *cache_id)
    p = percent_plus_escape (p, cache_id);
  else
    *p++ = 'X';
  *p++ = ' ';

  if (err_msg && *err_msg)
    p = percent_plus_escape (p, err_msg);
  else
    *p++ = 'X';
  *p++ = ' ';

  if (prompt && *prompt)
    p = percent_plus_escape (p, prompt);
  else
    *p++ = 'X'; 
  *p++ = ' ';

  if (desc_msg && *desc_msg)
    p = percent_plus_escape (p, desc_msg);
  else
    *p++ = 'X';
  *p = 0;

  init_membuf_secure (&data, 64);
  rc = assuan_transact (agent_ctx, line, 
                        membuf_data_cb, &data, NULL, NULL, NULL, NULL);

  if (rc)
    xfree (get_membuf (&data, NULL));
  else 
    {
      put_membuf (&data, "", 1);
      *r_passphrase = get_membuf (&data, NULL);
      if (!*r_passphrase)
        rc = gpg_error_from_syserror ();
    }
  xfree (line);
  return rc;
}


gpg_error_t
agent_clear_passphrase (const char *cache_id)
{
  int rc;
  char line[ASSUAN_LINELENGTH];

  if (!cache_id || !*cache_id)
    return 0;

  rc = start_agent ();
  if (rc)
    return rc;

  snprintf (line, DIM(line)-1, "CLEAR_PASSPHRASE %s", cache_id);
  line[DIM(line)-1] = 0;
  return assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
}