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mu/lib/mu-msg-crypto.c

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/*
** Copyright (C) 2012 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
**
** This program 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, or (at your option) any
** later version.
**
** 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 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.
**
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif /*HAVE_CONFIG_H*/
#include <string.h>
#include "mu-msg.h"
#include "mu-msg-priv.h"
#include "mu-msg-part.h"
#include "mu-date.h"
#include <gmime/gmime.h>
#include <gmime/gmime-multipart-signed.h>
#define CALLBACK_DATA "callback-data"
struct _CallbackData {
MuMsgPartPasswordFunc pw_func;
gpointer user_data;
};
typedef struct _CallbackData CallbackData;
static gboolean
password_requester (GMimeCryptoContext *ctx, const char *user_id,
const char* prompt_ctx, gboolean reprompt,
GMimeStream *response, GError **err)
{
CallbackData *cbdata;
gchar *password;
ssize_t written;
cbdata = g_object_get_data (G_OBJECT(ctx), CALLBACK_DATA);
if (!cbdata || !cbdata->pw_func)
return FALSE;
password = cbdata->pw_func (user_id, prompt_ctx, reprompt,
cbdata->user_data);
if (!password) {
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"failed to get password");
return FALSE;
}
written = g_mime_stream_write_string (response, password);
if (written != -1)
written = g_mime_stream_write_string (response, "\n");
if (written == -1)
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"writing password to mime stream failed");
/* it seems that GMime tries to flush the fd; however, this
* does not work for pipes/sockets, causing getting a password
* to fail.
*
* I have reported this, and it has been fixed now:
*
* http://git.gnome.org/browse/gmime/commit/
* ?id=bda4834d3d9a1fbefb6d97edfef2bc1da9357f58
*
* however, it may take a while before everybody has this
* version of GMime (ie. version > 2.6.10)
*
*/
memset (password, 0, strlen(password));
g_free (password);
return written != -1 ? TRUE : FALSE;
}
static char*
dummy_password_func (const char *user_id, const char *prompt_ctx,
gboolean reprompt, gpointer user_data)
{
g_print ("password requested for %s (%s) %s\n",
user_id, prompt_ctx, reprompt ? "again" : "");
return NULL;
}
static GMimeCryptoContext*
get_gpg_crypto_context (MuMsgOptions opts, GError **err)
{
GMimeCryptoContext *cctx;
const char *prog;
cctx = NULL;
prog = g_getenv ("MU_GPG_PATH");
if (prog)
cctx = g_mime_gpg_context_new (
(GMimePasswordRequestFunc)password_requester, prog);
else {
char *path;
path = g_find_program_in_path ("gpg");
if (path)
cctx = g_mime_gpg_context_new (
password_requester, path);
g_free (path);
}
if (!cctx) {
mu_util_g_set_error (err, MU_ERROR,
"failed to get GPG crypto context");
return NULL;
}
/* always try to use the agent */
g_mime_gpg_context_set_use_agent (GMIME_GPG_CONTEXT(cctx), TRUE);
g_mime_gpg_context_set_auto_key_retrieve
(GMIME_GPG_CONTEXT(cctx),
opts & MU_MSG_OPTION_AUTO_RETRIEVE ? TRUE:FALSE);
return cctx;
}
static GMimeCryptoContext*
get_crypto_context (MuMsgOptions opts, MuMsgPartPasswordFunc password_func,
gpointer user_data, GError **err)
{
CallbackData *cbdata;
GMimeCryptoContext *cctx;
cctx = get_gpg_crypto_context (opts, err);
/* use gobject to pass data to the callback func */
cbdata = g_new0 (CallbackData, 1);
cbdata->pw_func = password_func ? password_func : dummy_password_func;
cbdata->user_data = user_data;
g_object_set_data_full (G_OBJECT(cctx), CALLBACK_DATA,
cbdata, (GDestroyNotify)g_free);
return cctx;
}
static const char*
get_pubkey_algo_name (GMimePubKeyAlgo algo)
{
switch (algo) {
case GMIME_PUBKEY_ALGO_DEFAULT:
return "default";
case GMIME_PUBKEY_ALGO_RSA:
return "RSA";
case GMIME_PUBKEY_ALGO_RSA_E:
return "RSA (encryption only)";
case GMIME_PUBKEY_ALGO_RSA_S:
return "RSA (signing only)";
case GMIME_PUBKEY_ALGO_ELG_E:
return "ElGamal (encryption only)";
case GMIME_PUBKEY_ALGO_DSA:
return "DSA";
case GMIME_PUBKEY_ALGO_ELG:
return "ElGamal";
default:
return "unknown pubkey algorithm";
}
}
static const gchar*
get_digestkey_algo_name (GMimeDigestAlgo algo)
{
switch (algo) {
case GMIME_DIGEST_ALGO_DEFAULT:
return "default";
case GMIME_DIGEST_ALGO_MD5:
return "MD5";
case GMIME_DIGEST_ALGO_SHA1:
return "SHA-1";
case GMIME_DIGEST_ALGO_RIPEMD160:
return "RIPEMD160";
case GMIME_DIGEST_ALGO_MD2:
return "MD2";
case GMIME_DIGEST_ALGO_TIGER192:
return "TIGER-192";
case GMIME_DIGEST_ALGO_HAVAL5160:
return "HAVAL-5-160";
case GMIME_DIGEST_ALGO_SHA256:
return "SHA-256";
case GMIME_DIGEST_ALGO_SHA384:
return "SHA-384";
case GMIME_DIGEST_ALGO_SHA512:
return "SHA-512";
case GMIME_DIGEST_ALGO_SHA224:
return "SHA-224";
case GMIME_DIGEST_ALGO_MD4:
return "MD4";
default:
return "unknown digest algorithm";
}
}
/* get data from the 'certificate' */
static char*
get_cert_data (GMimeCertificate *cert)
{
const char *email, *name, *digest_algo, *pubkey_algo,
*keyid, *trust;
email = g_mime_certificate_get_email (cert);
name = g_mime_certificate_get_name (cert);
keyid = g_mime_certificate_get_key_id (cert);
digest_algo = get_digestkey_algo_name
(g_mime_certificate_get_digest_algo (cert));
pubkey_algo = get_pubkey_algo_name
(g_mime_certificate_get_pubkey_algo (cert));
switch (g_mime_certificate_get_trust (cert)) {
case GMIME_CERTIFICATE_TRUST_NONE: trust = "none"; break;
case GMIME_CERTIFICATE_TRUST_NEVER: trust = "never"; break;
case GMIME_CERTIFICATE_TRUST_UNDEFINED: trust = "undefined"; break;
case GMIME_CERTIFICATE_TRUST_MARGINAL: trust = "marginal"; break;
case GMIME_CERTIFICATE_TRUST_FULLY: trust = "full"; break;
case GMIME_CERTIFICATE_TRUST_ULTIMATE: trust = "ultimate"; break;
default:
g_return_val_if_reached (NULL);
}
return g_strdup_printf (
"signed by: %s <%s>; "
"algos: <%s,%s>; key-id: %s; trust: %s",
name ? name : "?", email ? email : "?",
pubkey_algo, digest_algo, keyid, trust);
}
/* get a human-readable report about the signature */
static char*
get_verdict_report (GMimeSignature *msig)
{
time_t t;
const char *status, *created, *expires;
gchar *certdata, *report;
switch (g_mime_signature_get_status (msig)) {
case GMIME_SIGNATURE_STATUS_GOOD: status = "good"; break;
case GMIME_SIGNATURE_STATUS_ERROR: status = "error"; break;
case GMIME_SIGNATURE_STATUS_BAD: status = "bad"; break;
default: g_return_val_if_reached (NULL);
}
t = g_mime_signature_get_created (msig);
created = (t == 0 || t == (time_t)-1) ? "?" : mu_date_str_s ("%x", t);
t = g_mime_signature_get_expires (msig);
expires = (t == 0 || t == (time_t)-1) ? "?" : mu_date_str_s ("%x", t);
certdata = get_cert_data (g_mime_signature_get_certificate (msig));
report = g_strdup_printf ("status: %s; created: %s, expires: %s (%s)",
status, created, expires,
certdata ? certdata : "?");
g_free (certdata);
return report;
}
static MuMsgPartSigStatusReport*
get_status_report (GMimeSignatureList *sigs)
{
int i;
MuMsgPartSigStatus status;
MuMsgPartSigStatusReport *status_report;
char *report;
status = MU_MSG_PART_SIG_STATUS_GOOD; /* let's start positive! */
for (i = 0, report = NULL; i != g_mime_signature_list_length (sigs); ++i) {
GMimeSignature *msig;
GMimeSignatureStatus sigstat;
gchar *rep;
msig = g_mime_signature_list_get_signature (sigs, i);
sigstat = g_mime_signature_get_status (msig);
switch (sigstat) {
case GMIME_SIGNATURE_STATUS_GOOD: break;
case GMIME_SIGNATURE_STATUS_ERROR:
status = MU_MSG_PART_SIG_STATUS_ERROR;
break;
case GMIME_SIGNATURE_STATUS_BAD:
status = MU_MSG_PART_SIG_STATUS_BAD;
break;
default: g_return_val_if_reached (NULL);
}
rep = get_verdict_report (msig);
report = g_strdup_printf ("%s%s[%d] %s", report ? report : "",
report ? "; " : "", i, rep);
g_free (rep);
}
status_report = g_slice_new (MuMsgPartSigStatusReport);
status_report->verdict = status;
status_report->report = report;
return status_report;
}
void
mu_msg_part_sig_status_report_destroy (MuMsgPartSigStatusReport *report)
{
if (!report)
return;
g_free ((char*)report->report);
g_slice_free (MuMsgPartSigStatusReport, report);
}
MuMsgPartSigStatusReport*
mu_msg_crypto_verify_part (GMimeMultipartSigned *sig, MuMsgOptions opts,
GError **err)
{
MuMsgPartSigStatusReport *report;
GMimeCryptoContext *ctx;
GMimeSignatureList *sigs;
g_return_val_if_fail (GMIME_IS_MULTIPART_SIGNED(sig), NULL);
ctx = get_crypto_context (opts, NULL, NULL, err);
if (!ctx) {
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"failed to get crypto context");
return NULL;
}
sigs = g_mime_multipart_signed_verify (sig, ctx, err);
g_object_unref (ctx);
if (!sigs) {
if (err && !*err)
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"verification failed");
return NULL;
}
report = get_status_report (sigs);
g_mime_signature_list_clear (sigs);
return report;
}
GMimeObject* /* this is declared in mu-msg-priv.h */
mu_msg_crypto_decrypt_part (GMimeMultipartEncrypted *enc, MuMsgOptions opts,
MuMsgPartPasswordFunc func, gpointer user_data,
GError **err)
{
GMimeObject *dec;
GMimeCryptoContext *ctx;
GMimeDecryptResult *res;
g_return_val_if_fail (GMIME_IS_MULTIPART_ENCRYPTED(enc), NULL);
ctx = get_crypto_context (opts, func, user_data, err);
if (!ctx) {
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"failed to get crypto context");
return NULL;
}
/* at the time of writing, there is a small leak in
* g_mime_multipart_encrypted_decrypt; I've notified its
* author and it has been fixed 2012-09-12:
* http://git.gnome.org/browse/gmime/commit/
* ?id=1bacd43b50d91bd03a4ae1dc9f46f5783dee61b1
* (or GMime > 2.6.10)
* */
res = NULL;
dec = g_mime_multipart_encrypted_decrypt (enc, ctx, &res, err);
g_object_unref (ctx);
/* we don't use the 3rd param 'res' * (GMimeDecryptResult),
* but we must unref it. */
if (res)
g_object_unref (res);
if (!dec) {
if (err && !*err)
mu_util_g_set_error (err, MU_ERROR_CRYPTO,
"decryption failed");
return NULL;
}
return dec;
}
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