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call-agent.c
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/* call-agent.c - divert operations to the agent
* Copyright (C) 2001, 2002 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include <gcrypt.h>
#include "gpgsm.h"
#include "../assuan/assuan.h"
#include "i18n.h"
static ASSUAN_CONTEXT agent_ctx = NULL;
static int force_pipe_server = 0;
struct cipher_parm_s {
ASSUAN_CONTEXT ctx;
const char *ciphertext;
size_t ciphertextlen;
};
struct genkey_parm_s {
ASSUAN_CONTEXT ctx;
const char *sexp;
size_t sexplen;
};
struct membuf {
size_t len;
size_t size;
char *buf;
int out_of_core;
};
/* A simple implemnation of a dynamic buffer. Use init_membuf() to
create a buffer, put_membuf to append bytes and get_membuf to
release and return the buffer. Allocation errors are detected but
only returned at the final get_membuf(), this helps not to clutter
the code with out of core checks. */
static void
init_membuf (struct membuf *mb, int initiallen)
{
mb->len = 0;
mb->size = initiallen;
mb->out_of_core = 0;
mb->buf = xtrymalloc (initiallen);
if (!mb->buf)
mb->out_of_core = 1;
}
static void
put_membuf (struct membuf *mb, const void *buf, size_t len)
{
if (mb->out_of_core)
return;
if (mb->len + len >= mb->size)
{
char *p;
mb->size += len + 1024;
p = xtryrealloc (mb->buf, mb->size);
if (!p)
{
mb->out_of_core = 1;
return;
}
mb->buf = p;
}
memcpy (mb->buf + mb->len, buf, len);
mb->len += len;
}
static void *
get_membuf (struct membuf *mb, size_t *len)
{
char *p;
if (mb->out_of_core)
{
xfree (mb->buf);
mb->buf = NULL;
return NULL;
}
p = mb->buf;
*len = mb->len;
mb->buf = NULL;
mb->out_of_core = 1; /* don't allow a reuse */
return p;
}
/* 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)
{
int rc;
char *infostr, *p;
ASSUAN_CONTEXT ctx;
if (agent_ctx)
return 0; /* fixme: We need a context for each thread or serialize
the access to the agent (which is suitable given that
the agent is not MT */
infostr = force_pipe_server? NULL : getenv ("GPG_AGENT_INFO");
if (!infostr)
{
const char *pgmname;
const char *argv[3];
log_info (_("no running gpg-agent - starting one\n"));
if (fflush (NULL))
{
log_error ("error flushing pending output: %s\n", strerror (errno));
return seterr (Write_Error);
}
if (!opt.agent_program || !*opt.agent_program)
opt.agent_program = "../agent/gpg-agent";
if ( !(pgmname = strrchr (opt.agent_program, '/')))
pgmname = opt.agent_program;
else
pgmname++;
argv[0] = pgmname;
argv[1] = "--server";
argv[2] = NULL;
/* connect to the agent and perform initial handshaking */
rc = assuan_pipe_connect (&ctx, opt.agent_program, (char**)argv, 0);
}
else
{
int prot;
int pid;
infostr = xstrdup (infostr);
if ( !(p = strchr (infostr, ':')) || p == infostr)
{
log_error (_("malformed GPG_AGENT_INFO environment variable\n"));
xfree (infostr);
force_pipe_server = 1;
return start_agent ();
}
*p++ = 0;
pid = atoi (p);
while (*p && *p != ':')
p++;
prot = *p? atoi (p+1) : 0;
if (prot != 1)
{
log_error (_("gpg-agent protocol version %d is not supported\n"),
prot);
xfree (infostr);
force_pipe_server = 1;
return start_agent ();
}
rc = assuan_socket_connect (&ctx, infostr, pid);
xfree (infostr);
if (rc == ASSUAN_Connect_Failed)
{
log_error (_("can't connect to the agent - trying fall back\n"));
force_pipe_server = 1;
return start_agent ();
}
}
if (rc)
{
log_error ("can't connect to the agent: %s\n", assuan_strerror (rc));
return seterr (No_Agent);
}
agent_ctx = ctx;
if (DBG_AGENT)
log_debug ("connection to agent established\n");
return 0;
}
static AssuanError
membuf_data_cb (void *opaque, const void *buffer, size_t length)
{
struct membuf *data = opaque;
put_membuf (data, buffer, length);
return 0;
}
/* Call the agent to do a sign operation using the key identified by
the hex string KEYGRIP. */
int
gpgsm_agent_pksign (const char *keygrip,
unsigned char *digest, size_t digestlen, int digestalgo,
char **r_buf, size_t *r_buflen )
{
int rc, i;
char *p, line[ASSUAN_LINELENGTH];
struct membuf data;
size_t len;
*r_buf = NULL;
rc = start_agent ();
if (rc)
return rc;
if (digestlen*2 + 50 > DIM(line))
return seterr (General_Error);
rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
snprintf (line, DIM(line)-1, "SIGKEY %s", keygrip);
line[DIM(line)-1] = 0;
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
sprintf (line, "SETHASH %d ", digestalgo);
p = line + strlen (line);
for (i=0; i < digestlen ; i++, p += 2 )
sprintf (p, "%02X", digest[i]);
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
init_membuf (&data, 1024);
rc = assuan_transact (agent_ctx, "PKSIGN",
membuf_data_cb, &data, NULL, NULL);
if (rc)
{
xfree (get_membuf (&data, &len));
return map_assuan_err (rc);
}
*r_buf = get_membuf (&data, r_buflen);
if (!gcry_sexp_canon_len (*r_buf, *r_buflen, NULL, NULL))
{
xfree (*r_buf); *r_buf = NULL;
return GNUPG_Invalid_Value;
}
return *r_buf? 0 : GNUPG_Out_Of_Core;
}
/* Handle a CIPHERTEXT inquiry. Note, we only send the data,
assuan_transact talkes care of flushing and writing the end */
static AssuanError
inq_ciphertext_cb (void *opaque, const char *keyword)
{
struct cipher_parm_s *parm = opaque;
AssuanError rc;
assuan_begin_confidential (parm->ctx);
rc = assuan_send_data (parm->ctx, parm->ciphertext, parm->ciphertextlen);
assuan_end_confidential (parm->ctx);
return rc;
}
/* Call the agent to do a decrypt operation using the key identified by
the hex string KEYGRIP. */
int
gpgsm_agent_pkdecrypt (const char *keygrip,
KsbaConstSexp ciphertext,
char **r_buf, size_t *r_buflen )
{
int rc;
char line[ASSUAN_LINELENGTH];
struct membuf data;
struct cipher_parm_s cipher_parm;
size_t n, len;
char *buf, *endp;
size_t ciphertextlen;
if (!keygrip || strlen(keygrip) != 40 || !ciphertext || !r_buf || !r_buflen)
return GNUPG_Invalid_Value;
*r_buf = NULL;
ciphertextlen = gcry_sexp_canon_len (ciphertext, 0, NULL, NULL);
if (!ciphertextlen)
return GNUPG_Invalid_Value;
rc = start_agent ();
if (rc)
return rc;
rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
assert ( DIM(line) >= 50 );
snprintf (line, DIM(line)-1, "SETKEY %s", keygrip);
line[DIM(line)-1] = 0;
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
init_membuf (&data, 1024);
cipher_parm.ctx = agent_ctx;
cipher_parm.ciphertext = ciphertext;
cipher_parm.ciphertextlen = ciphertextlen;
rc = assuan_transact (agent_ctx, "PKDECRYPT",
membuf_data_cb, &data,
inq_ciphertext_cb, &cipher_parm);
if (rc)
{
xfree (get_membuf (&data, &len));
return map_assuan_err (rc);
}
put_membuf (&data, "", 1); /* make sure it is 0 terminated */
buf = get_membuf (&data, &len);
if (!buf)
return seterr (Out_Of_Core);
/* FIXME: We would better a return a full S-exp and not just a part */
assert (len);
len--; /* remove the terminating 0 */
n = strtoul (buf, &endp, 10);
if (!n || *endp != ':')
return seterr (Invalid_Sexp);
endp++;
if (endp-buf+n > len)
return seterr (Invalid_Sexp); /* oops len does not match internal len*/
memmove (buf, endp, n);
*r_buflen = n;
*r_buf = buf;
return 0;
}
/* Handle a KEYPARMS inquiry. Note, we only send the data,
assuan_transact takes care of flushing and writing the end */
static AssuanError
inq_genkey_parms (void *opaque, const char *keyword)
{
struct genkey_parm_s *parm = opaque;
AssuanError rc;
rc = assuan_send_data (parm->ctx, parm->sexp, parm->sexplen);
return rc;
}
/* Call the agent to generate a newkey */
int
gpgsm_agent_genkey (KsbaConstSexp keyparms, KsbaSexp *r_pubkey)
{
int rc;
struct genkey_parm_s gk_parm;
struct membuf data;
size_t len;
char *buf;
*r_pubkey = NULL;
rc = start_agent ();
if (rc)
return rc;
rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL);
if (rc)
return map_assuan_err (rc);
init_membuf (&data, 1024);
gk_parm.ctx = agent_ctx;
gk_parm.sexp = keyparms;
gk_parm.sexplen = gcry_sexp_canon_len (keyparms, 0, NULL, NULL);
if (!gk_parm.sexplen)
return GNUPG_Invalid_Value;
rc = assuan_transact (agent_ctx, "GENKEY",
membuf_data_cb, &data,
inq_genkey_parms, &gk_parm);
if (rc)
{
xfree (get_membuf (&data, &len));
return map_assuan_err (rc);
}
buf = get_membuf (&data, &len);
if (!buf)
return GNUPG_Out_Of_Core;
if (!gcry_sexp_canon_len (buf, len, NULL, NULL))
{
xfree (buf);
return GNUPG_Invalid_Sexp;
}
*r_pubkey = buf;
return 0;
}
/* Ask the agent whether the certificate is in the list of trusted
keys */
int
gpgsm_agent_istrusted (KsbaCert cert)
{
int rc;
char *fpr;
char line[ASSUAN_LINELENGTH];
rc = start_agent ();
if (rc)
return rc;
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
if (!fpr)
{
log_error ("error getting the fingerprint\n");
return seterr (General_Error);
}
snprintf (line, DIM(line)-1, "ISTRUSTED %s", fpr);
line[DIM(line)-1] = 0;
xfree (fpr);
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
return map_assuan_err (rc);
}
/* Ask the agent to mark CERT as a trusted Root-CA one */
int
gpgsm_agent_marktrusted (KsbaCert cert)
{
int rc;
char *fpr, *dn;
char line[ASSUAN_LINELENGTH];
rc = start_agent ();
if (rc)
return rc;
fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
if (!fpr)
{
log_error ("error getting the fingerprint\n");
return seterr (General_Error);
}
dn = ksba_cert_get_issuer (cert, 0);
if (!dn)
{
xfree (fpr);
return seterr (General_Error);
}
snprintf (line, DIM(line)-1, "MARKTRUSTED %s S %s", fpr, dn);
line[DIM(line)-1] = 0;
ksba_free (dn);
xfree (fpr);
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
return map_assuan_err (rc);
}
/* Ask the agent whether the a corresponding secret key is available
for the given keygrip */
int
gpgsm_agent_havekey (const char *hexkeygrip)
{
int rc;
char line[ASSUAN_LINELENGTH];
rc = start_agent ();
if (rc)
return rc;
if (!hexkeygrip || strlen (hexkeygrip) != 40)
return GNUPG_Invalid_Value;
snprintf (line, DIM(line)-1, "HAVEKEY %s", hexkeygrip);
line[DIM(line)-1] = 0;
rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL);
return map_assuan_err (rc);
}

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