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wireshark/wsutil/rsa.c

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/* rsa.c
*
* Functions for RSA private key reading and use
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 2007 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#define WS_LOG_DOMAIN LOG_DOMAIN_WSUTIL
#include "rsa.h"
#include <glib.h>
#include "filesystem.h"
#include "file_util.h"
#include <errno.h>
#include <wsutil/wslog.h>
#ifdef HAVE_LIBGNUTLS
#include <gnutls/abstract.h>
#include <gnutls/pkcs12.h>
/* RSA private key file processing {{{ */
#define RSA_PARS 6
gcry_sexp_t
rsa_privkey_to_sexp(gnutls_x509_privkey_t priv_key, char **err)
{
gnutls_datum_t rsa_datum[RSA_PARS]; /* m, e, d, p, q, u */
size_t tmp_size;
gcry_error_t gret;
gcry_sexp_t rsa_priv_key = NULL;
gint i;
gcry_mpi_t rsa_params[RSA_PARS];
*err = NULL;
/* RSA get parameter */
if (gnutls_x509_privkey_export_rsa_raw(priv_key,
&rsa_datum[0],
&rsa_datum[1],
&rsa_datum[2],
&rsa_datum[3],
&rsa_datum[4],
&rsa_datum[5]) != 0) {
*err = g_strdup("can't export rsa param (is a rsa private key file ?!?)");
return NULL;
}
/* convert each rsa parameter to mpi format*/
for(i=0; i<RSA_PARS; i++) {
gret = gcry_mpi_scan(&rsa_params[i], GCRYMPI_FMT_USG, rsa_datum[i].data, rsa_datum[i].size,&tmp_size);
/* these buffers were allocated by gnutls_x509_privkey_export_rsa_raw() */
g_free(rsa_datum[i].data);
if (gret != 0) {
*err = ws_strdup_printf("can't convert m rsa param to int (size %d)", rsa_datum[i].size);
return NULL;
}
}
/* libgcrypt expects p < q, and gnutls might not return it as such, depending on gnutls version and its crypto backend */
if (gcry_mpi_cmp(rsa_params[3], rsa_params[4]) > 0)
{
/* p, q = q, p */
gcry_mpi_swap(rsa_params[3], rsa_params[4]);
/* due to swapping p and q, u = p^-1 mod p which happens to be needed. */
}
/* libgcrypt expects u = p^-1 mod q (for OpenPGP), but the u parameter
* says u = q^-1 mod p. Recompute u = p^-1 mod q. Do this unconditionally as
* at least GnuTLS 2.12.23 computes an invalid value. */
gcry_mpi_invm(rsa_params[5], rsa_params[3], rsa_params[4]);
if (gcry_sexp_build( &rsa_priv_key, NULL,
"(private-key(rsa((n%m)(e%m)(d%m)(p%m)(q%m)(u%m))))", rsa_params[0],
rsa_params[1], rsa_params[2], rsa_params[3], rsa_params[4],
rsa_params[5]) != 0) {
*err = g_strdup("can't build rsa private key s-exp");
return NULL;
}
for (i=0; i< 6; i++)
gcry_mpi_release(rsa_params[i]);
return rsa_priv_key;
}
gnutls_x509_privkey_t
rsa_load_pem_key(FILE *fp, char **err)
{
/* gnutls makes our work much harder, since we have to work internally with
* s-exp formatted data, but PEM loader exports only in "gnutls_datum_t"
* format, and a datum -> s-exp conversion function does not exist.
*/
gnutls_x509_privkey_t priv_key;
gnutls_datum_t key;
ws_statb64 statbuf;
gint ret;
guint bytes;
*err = NULL;
if (ws_fstat64(ws_fileno(fp), &statbuf) == -1) {
*err = ws_strdup_printf("can't ws_fstat64 file: %s", g_strerror(errno));
return NULL;
}
if (S_ISDIR(statbuf.st_mode)) {
*err = g_strdup("file is a directory");
errno = EISDIR;
return NULL;
}
if (S_ISFIFO(statbuf.st_mode)) {
*err = g_strdup("file is a named pipe");
errno = EINVAL;
return NULL;
}
if (!S_ISREG(statbuf.st_mode)) {
*err = g_strdup("file is not a regular file");
errno = EINVAL;
return NULL;
}
/* XXX - check for a too-big size */
/* load all file contents into a datum buffer*/
key.data = (unsigned char *)g_malloc((size_t)statbuf.st_size);
key.size = (int)statbuf.st_size;
bytes = (guint) fread(key.data, 1, key.size, fp);
if (bytes < key.size) {
if (bytes == 0 && ferror(fp)) {
*err = ws_strdup_printf("can't read from file %d bytes, got error %s",
key.size, g_strerror(errno));
} else {
*err = ws_strdup_printf("can't read from file %d bytes, got %d",
key.size, bytes);
}
g_free(key.data);
return NULL;
}
/* init private key data*/
gnutls_x509_privkey_init(&priv_key);
/* import PEM data*/
if ((ret = gnutls_x509_privkey_import(priv_key, &key, GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS) {
*err = ws_strdup_printf("can't import pem data: %s", gnutls_strerror(ret));
g_free(key.data);
gnutls_x509_privkey_deinit(priv_key);
return NULL;
}
if (gnutls_x509_privkey_get_pk_algorithm(priv_key) != GNUTLS_PK_RSA) {
*err = g_strdup("private key public key algorithm isn't RSA");
g_free(key.data);
gnutls_x509_privkey_deinit(priv_key);
return NULL;
}
g_free(key.data);
return priv_key;
}
static const char *
BAGTYPE(gnutls_pkcs12_bag_type_t x) {
switch (x) {
case GNUTLS_BAG_EMPTY: return "Empty";
case GNUTLS_BAG_PKCS8_ENCRYPTED_KEY: return "PKCS#8 Encrypted key";
case GNUTLS_BAG_PKCS8_KEY: return "PKCS#8 Key";
case GNUTLS_BAG_CERTIFICATE: return "Certificate";
case GNUTLS_BAG_CRL: return "CRL";
case GNUTLS_BAG_ENCRYPTED: return "Encrypted";
case GNUTLS_BAG_UNKNOWN: return "Unknown";
default: return "<undefined>";
}
}
gnutls_x509_privkey_t
rsa_load_pkcs12(FILE *fp, const gchar *cert_passwd, char **err)
{
int i, j, ret;
int rest;
unsigned char *p;
gnutls_datum_t data;
gnutls_pkcs12_bag_t bag = NULL;
size_t len;
gnutls_pkcs12_t rsa_p12 = NULL;
gnutls_x509_privkey_t priv_key = NULL;
*err = NULL;
rest = 4096;
data.data = (unsigned char *)g_malloc(rest);
data.size = rest;
p = data.data;
while ((len = fread(p, 1, rest, fp)) > 0) {
p += len;
rest -= (int) len;
if (!rest) {
rest = 1024;
data.data = (unsigned char *)g_realloc(data.data, data.size + rest);
p = data.data + data.size;
data.size += rest;
}
}
data.size -= rest;
if (!feof(fp)) {
*err = g_strdup("Error during certificate reading.");
g_free(data.data);
return NULL;
}
ret = gnutls_pkcs12_init(&rsa_p12);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_init(&st_p12) - %s", gnutls_strerror(ret));
g_free(data.data);
return NULL;
}
/* load PKCS#12 in DER or PEM format */
ret = gnutls_pkcs12_import(rsa_p12, &data, GNUTLS_X509_FMT_DER, 0);
if (ret < 0) {
ret = gnutls_pkcs12_import(rsa_p12, &data, GNUTLS_X509_FMT_PEM, 0);
if (ret < 0) {
*err = ws_strdup_printf("could not load PKCS#12 in DER or PEM format: %s", gnutls_strerror(ret));
}
}
g_free(data.data);
if (ret < 0) {
gnutls_pkcs12_deinit(rsa_p12);
return NULL;
}
ws_debug("grsa_privkey_to_sexp: PKCS#12 imported");
/* TODO: Use gnutls_pkcs12_simple_parse, since 3.1.0 (August 2012) */
for (i=0; ; i++) {
gnutls_pkcs12_bag_type_t bag_type;
ret = gnutls_pkcs12_bag_init(&bag);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_init failed: %s",
gnutls_strerror(ret));
goto done;
}
ret = gnutls_pkcs12_get_bag(rsa_p12, i, bag);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_get_bag failed: %s",
gnutls_strerror(ret));
goto done;
}
for (j=0; j<gnutls_pkcs12_bag_get_count(bag); j++) {
ret = gnutls_pkcs12_bag_get_type(bag, j);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_get_type failed: %s",
gnutls_strerror(ret));
goto done;
}
bag_type = (gnutls_pkcs12_bag_type_t)ret;
if (bag_type >= GNUTLS_BAG_UNKNOWN) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_get_type returned unknown bag type %u",
ret);
goto done;
}
ws_debug("Bag %d/%d: %s", i, j, BAGTYPE(bag_type));
if (bag_type == GNUTLS_BAG_ENCRYPTED) {
ret = gnutls_pkcs12_bag_decrypt(bag, cert_passwd);
if (ret == 0) {
ret = gnutls_pkcs12_bag_get_type(bag, j);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_get_type failed: %s",
gnutls_strerror(ret));
goto done;
}
bag_type = (gnutls_pkcs12_bag_type_t)ret;
if (bag_type >= GNUTLS_BAG_UNKNOWN) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_get_type returned unknown bag type %u",
ret);
goto done;
}
ws_debug("Bag %d/%d decrypted: %s", i, j, BAGTYPE(bag_type));
}
}
ret = gnutls_pkcs12_bag_get_data(bag, j, &data);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_pkcs12_bag_get_data failed: %s",
gnutls_strerror(ret));
goto done;
}
switch (bag_type) {
case GNUTLS_BAG_PKCS8_KEY:
case GNUTLS_BAG_PKCS8_ENCRYPTED_KEY:
{
gnutls_x509_privkey_t rsa_pkey;
ret = gnutls_x509_privkey_init(&rsa_pkey);
if (ret < 0) {
*err = ws_strdup_printf("gnutls_x509_privkey_init failed: %s", gnutls_strerror(ret));
goto done;
}
ret = gnutls_x509_privkey_import_pkcs8(rsa_pkey, &data, GNUTLS_X509_FMT_DER, cert_passwd,
(bag_type==GNUTLS_BAG_PKCS8_KEY) ? GNUTLS_PKCS_PLAIN : 0);
if (ret < 0) {
*err = ws_strdup_printf("Can not decrypt private key - %s", gnutls_strerror(ret));
gnutls_x509_privkey_deinit(rsa_pkey);
goto done;
}
if (gnutls_x509_privkey_get_pk_algorithm(rsa_pkey) != GNUTLS_PK_RSA) {
*err = g_strdup("private key public key algorithm isn't RSA");
gnutls_x509_privkey_deinit(rsa_pkey);
goto done;
}
/* Private key found, return it. */
priv_key = rsa_pkey;
goto done;
}
default: ;
}
} /* j */
gnutls_pkcs12_bag_deinit(bag);
bag = NULL;
} /* i */
done:
if (bag) {
gnutls_pkcs12_bag_deinit(bag);
}
if (!priv_key) {
/*
* We failed. If we didn't fail with an error, we failed because
* we found no PKCS8 key and fell out of the loop; report that
* error.
*/
if (*err == NULL)
*err = g_strdup("no PKCS8 key found");
}
gnutls_pkcs12_deinit(rsa_p12);
return priv_key;
}
void
rsa_private_key_free(gpointer key)
{
gcry_sexp_release((gcry_sexp_t) key);
}
#else /* ! defined(HAVE_LIBGNUTLS) */
void
rsa_private_key_free(gpointer key _U_)
{
}
#endif /* HAVE_LIBGNUTLS */
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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