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wireshark/epan/secrets.c

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/* secrets.c
* Secrets management and processing.
* Copyright 2018, Peter Wu <peter@lekensteyn.nl>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#define WS_LOG_DOMAIN LOG_DOMAIN_EPAN
#include "secrets.h"
#include <wiretap/wtap.h>
#include <wsutil/glib-compat.h>
#include <wsutil/wslog.h>
#include <string.h>
#ifdef HAVE_LIBGNUTLS
# include <gnutls/gnutls.h>
# include <gnutls/abstract.h>
# include <wsutil/wsgcrypt.h>
# include <wsutil/rsa.h>
# include <epan/uat.h>
# include <wsutil/report_message.h>
# include <wsutil/file_util.h>
# include <errno.h>
# if GNUTLS_VERSION_NUMBER < 0x030401
# define GNUTLS_KEYID_USE_SHA1 0
# endif
#endif /* HAVE_LIBGNUTLS */
/** Maps guint32 secrets_type -> secrets_block_callback_t. */
static GHashTable *secrets_callbacks;
#ifdef HAVE_LIBGNUTLS
/** Maps public key IDs (cert_key_id_t) -> gnutls_privkey_t. */
static GHashTable *rsa_privkeys;
typedef struct {
char *uri; /**< User-supplied PKCS #11 URI for token or RSA private key file. */
char *password; /**< User-supplied PKCS #11 PIN or RSA private key file password. */
} rsa_privkey_record_t;
static uat_t *rsa_privkeys_uat;
static rsa_privkey_record_t *uat_rsa_privkeys;
static guint uat_num_rsa_privkeys;
static void register_rsa_uats(void);
#endif /* HAVE_LIBGNUTLS */
#ifdef HAVE_GNUTLS_PKCS11
/** PINs for PKCS #11 keys in rsa_privkeys. Must be cleared after rsa_privkeys. */
static GSList *rsa_privkeys_pkcs11_pins;
typedef struct {
char *library_path; /**< PKCS #11 library path. */
} pkcs11_lib_record_t;
static uat_t *pkcs11_libs_uat;
static pkcs11_lib_record_t *uat_pkcs11_libs;
static guint uat_num_pkcs11_libs;
#endif /* HAVE_GNUTLS_PKCS11 */
void
secrets_init(void)
{
secrets_callbacks = g_hash_table_new(g_direct_hash, g_direct_equal);
#ifdef HAVE_LIBGNUTLS
rsa_privkeys = privkey_hash_table_new();
register_rsa_uats();
#endif /* HAVE_LIBGNUTLS */
}
void
secrets_cleanup(void)
{
g_hash_table_destroy(secrets_callbacks);
secrets_callbacks = NULL;
#ifdef HAVE_LIBGNUTLS
g_hash_table_destroy(rsa_privkeys);
rsa_privkeys = NULL;
#ifdef HAVE_GNUTLS_PKCS11
g_slist_free_full(rsa_privkeys_pkcs11_pins, g_free);
rsa_privkeys_pkcs11_pins = NULL;
#endif /* HAVE_GNUTLS_PKCS11 */
#endif /* HAVE_LIBGNUTLS */
}
void
secrets_register_type(guint32 secrets_type, secrets_block_callback_t cb)
{
g_hash_table_insert(secrets_callbacks, GUINT_TO_POINTER(secrets_type), (gpointer)cb);
}
void
secrets_wtap_callback(guint32 secrets_type, const void *secrets, guint size)
{
secrets_block_callback_t cb = (secrets_block_callback_t)g_hash_table_lookup(
secrets_callbacks, GUINT_TO_POINTER(secrets_type));
if (cb) {
cb(secrets, size);
}
}
#ifdef HAVE_LIBGNUTLS
static guint
key_id_hash(gconstpointer key)
{
const cert_key_id_t *key_id = (const cert_key_id_t *)key;
const guint32 *dw = (const guint32 *)key_id->key_id;
/* The public key' SHA-1 hash (which maps to a private key) has a uniform
* distribution, hence simply xor'ing them should be sufficient. */
return dw[0] ^ dw[1] ^ dw[2] ^ dw[3] ^ dw[4];
}
static gboolean
key_id_equal(gconstpointer a, gconstpointer b)
{
const cert_key_id_t *key_id_a = (const cert_key_id_t *)a;
const cert_key_id_t *key_id_b = (const cert_key_id_t *)b;
return !memcmp(key_id_a, key_id_b, sizeof(*key_id_a));
}
GHashTable *
privkey_hash_table_new(void)
{
return g_hash_table_new_full(key_id_hash, key_id_equal, g_free, (GDestroyNotify)gnutls_privkey_deinit);
}
static void
rsa_privkey_add(const cert_key_id_t *key_id, gnutls_privkey_t pkey)
{
void *ht_key = g_memdup2(key_id->key_id, sizeof(cert_key_id_t));
const guint32 *dw = (const guint32 *)key_id->key_id;
g_hash_table_insert(rsa_privkeys, ht_key, pkey);
ws_debug("Adding RSA private, Key ID %08x%08x%08x%08x%08x", g_htonl(dw[0]),
g_htonl(dw[1]), g_htonl(dw[2]), g_htonl(dw[3]), g_htonl(dw[4]));
}
#ifdef HAVE_GNUTLS_PKCS11
/** Provides a fixed PIN to the caller (or failure if the fixed PIN is NULL). */
static int
set_pin_callback(void *userdata, int attempt _U_,
const char *token_url _U_, const char *token_label _U_,
unsigned int flags, char *pin, size_t pin_max)
{
const char *fixed_pin = (const char *)userdata;
size_t fixed_pin_len = fixed_pin ? strlen(fixed_pin) : 0;
/* Fail if the PIN was not provided, wrong or too long. */
if (!fixed_pin || (flags & GNUTLS_PIN_WRONG) || fixed_pin_len >= pin_max) {
return GNUTLS_E_PKCS11_PIN_ERROR;
}
memcpy(pin, fixed_pin, fixed_pin_len + 1);
return 0;
}
static GSList *
get_pkcs11_token_uris(void)
{
GSList *tokens = NULL;
for (unsigned i = 0; ; i++) {
char *uri = NULL;
int flags;
int ret = gnutls_pkcs11_token_get_url(i, GNUTLS_PKCS11_URL_GENERIC, &uri);
if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
break;
}
if (ret < 0) {
ws_debug("Failed to query token %u: %s\n", i, gnutls_strerror(ret));
break;
}
ret = gnutls_pkcs11_token_get_flags(uri, &flags);
if (ret < 0) {
ws_debug("Failed to query token flags for %s: %s\n", uri, gnutls_strerror(ret));
gnutls_free(uri);
continue;
}
// The "Trust module" is useless for decryption, so do not return it.
if ((flags & GNUTLS_PKCS11_TOKEN_TRUSTED)) {
gnutls_free(uri);
continue;
}
tokens = g_slist_prepend(tokens, g_strdup(uri));
gnutls_free(uri);
}
tokens = g_slist_reverse(tokens);
return tokens;
}
static gboolean
verify_pkcs11_token(const char *token_uri, const char *pin, gboolean *pin_needed, char **error)
{
gnutls_pkcs11_obj_t *list = NULL;
unsigned int nlist = 0;
int ret;
/* Set PIN via a global callback since import_url can prompt for one. */
gnutls_pkcs11_set_pin_function(set_pin_callback, (void *)pin);
/* This should ask for a PIN if needed. If no PIN is given,
* GNUTLS_E_PKCS11_PIN_ERROR (-303) is returned. */
ret = gnutls_pkcs11_obj_list_import_url4(&list, &nlist, token_uri,
GNUTLS_PKCS11_OBJ_FLAG_PRIVKEY|GNUTLS_PKCS11_OBJ_FLAG_LOGIN);
if (ret == 0) {
/* Do not care about the objects, we just wanted to know whether the
* token and PIN were valid. */
for (unsigned i = 0; i < nlist; i++) {
gnutls_pkcs11_obj_deinit(list[i]);
}
gnutls_free(list);
}
/* Forget about the PIN. */
gnutls_pkcs11_set_pin_function(NULL, NULL);
if (pin_needed) {
*pin_needed = ret == GNUTLS_E_PKCS11_PIN_ERROR;
}
if (ret != 0) {
if (error) {
*error = g_strdup(gnutls_strerror(ret));
}
return FALSE;
}
return TRUE;
}
/**
* Load private RSA keys from a PKCS #11 token. Returns zero on success and a
* negative error code on failure.
*/
static int
pkcs11_load_keys_from_token(const char *token_uri, const char *pin, char **err)
{
gnutls_pkcs11_obj_t *list = NULL;
unsigned int nlist = 0;
int ret;
/* An empty/NULL PIN means that none is necessary. */
char *fixed_pin = pin && pin[0] ? g_strdup(pin) : NULL;
gboolean pin_in_use = FALSE;
/* Set PIN via a global callback since import_url can prompt for one. */
gnutls_pkcs11_set_pin_function(set_pin_callback, fixed_pin);
/* This might already result in callback for the PIN. */
ret = gnutls_pkcs11_obj_list_import_url4(&list, &nlist, token_uri,
GNUTLS_PKCS11_OBJ_FLAG_PRIVKEY|GNUTLS_PKCS11_OBJ_FLAG_LOGIN);
if (ret < 0) {
*err = g_strdup_printf("Failed to iterate through objects for %s: %s", token_uri, gnutls_strerror(ret));
goto cleanup;
}
for (unsigned j = 0; j < nlist; j++) {
char *obj_uri = NULL;
gnutls_privkey_t privkey = NULL;
gnutls_pubkey_t pubkey = NULL;
cert_key_id_t key_id;
size_t size;
if (gnutls_pkcs11_obj_get_type(list[j]) != GNUTLS_PKCS11_OBJ_PRIVKEY) {
/* Should not happen since we requested private keys only. */
goto cont;
}
ret = gnutls_pkcs11_obj_export_url(list[j], GNUTLS_PKCS11_URL_GENERIC, &obj_uri);
if (ret < 0) {
/* Should not happen either if the object is valid. */
goto cont;
}
ret = gnutls_privkey_init(&privkey);
if (ret < 0) {
/* Out of memory? */
goto cont;
}
/* Set the PIN to be used during decryption. */
gnutls_privkey_set_pin_function(privkey, set_pin_callback, fixed_pin);
/* Can prompt for PIN. Can also invoke the token function set by
* gnutls_pkcs11_set_token_function (if not set, it will just fail
* immediately rather than retrying). */
ret = gnutls_privkey_import_url(privkey, obj_uri, 0);
if (ret < 0) {
/* Bad PIN or some other system error? */
ws_debug("Failed to import private key %s: %s", obj_uri, gnutls_strerror(ret));
goto cont;
}
if (gnutls_privkey_get_pk_algorithm(privkey, NULL) != GNUTLS_PK_RSA) {
ws_debug("Skipping private key %s, not RSA.", obj_uri);
goto cont;
}
ret = gnutls_pubkey_init(&pubkey);
if (ret < 0) {
/* Out of memory? */
goto cont;
}
/* This requires GnuTLS 3.4.0 and will fail on older versions. */
ret = gnutls_pubkey_import_privkey(pubkey, privkey, 0, 0);
if (ret < 0) {
ws_debug("Failed to import public key %s: %s", obj_uri, gnutls_strerror(ret));
goto cont;
}
size = sizeof(key_id);
ret = gnutls_pubkey_get_key_id(pubkey, GNUTLS_KEYID_USE_SHA1, key_id.key_id, &size);
if (ret < 0 || size != sizeof(key_id)) {
ws_debug("Failed to calculate Key ID for %s: %s", obj_uri, gnutls_strerror(ret));
goto cont;
}
/* Remember the private key. */
rsa_privkey_add(&key_id, privkey);
privkey = NULL;
pin_in_use = TRUE;
cont:
gnutls_privkey_deinit(privkey);
gnutls_pubkey_deinit(pubkey);
gnutls_free(obj_uri);
gnutls_pkcs11_obj_deinit(list[j]);
}
gnutls_free(list);
if (pin_in_use) {
/* Remember PINs such they can be freed later. */
rsa_privkeys_pkcs11_pins = g_slist_prepend(rsa_privkeys_pkcs11_pins, fixed_pin);
fixed_pin = NULL;
}
ret = 0;
cleanup:
/* Forget about the PIN. */
gnutls_pkcs11_set_pin_function(NULL, NULL);
g_free(fixed_pin);
return ret;
}
/** Load all libraries specified in a UAT. */
static void
uat_pkcs11_libs_load_all(void)
{
int ret;
GString *err = NULL;
for (guint i = 0; i < uat_num_pkcs11_libs; i++) {
const pkcs11_lib_record_t *rec = &uat_pkcs11_libs[i];
const char *libname = rec->library_path;
#ifdef WIN32
// Work around a bug in p11-kit < 0.23.16 on Windows
HMODULE provider_lib = LoadLibraryA(libname);
if (! provider_lib || ! GetProcAddress(provider_lib, "C_GetFunctionList")) {
ret = GNUTLS_E_PKCS11_LOAD_ERROR;
} else {
#endif
/* Note: should return success for already loaded libraries. */
ret = gnutls_pkcs11_add_provider(libname, NULL);
#ifdef WIN32
}
if (provider_lib) {
FreeLibrary(provider_lib);
}
#endif
if (ret) {
if (!err) {
err = g_string_new("Error loading PKCS #11 libraries:");
}
g_string_append_printf(err, "\n%s: %s", libname, gnutls_strerror(ret));
}
}
if (err) {
report_failure("%s", err->str);
g_string_free(err, TRUE);
}
}
UAT_FILENAME_CB_DEF(pkcs11_libs_uats, library_path, pkcs11_lib_record_t)
static void *
uat_pkcs11_lib_copy_str_cb(void *dest, const void *source, size_t len _U_)
{
pkcs11_lib_record_t *d = (pkcs11_lib_record_t *)dest;
const pkcs11_lib_record_t *s = (const pkcs11_lib_record_t *)source;
d->library_path = g_strdup(s->library_path);
return dest;
}
static void
uat_pkcs11_lib_free_str_cb(void *record)
{
pkcs11_lib_record_t *rec = (pkcs11_lib_record_t *)record;
g_free(rec->library_path);
}
#endif /* HAVE_GNUTLS_PKCS11 */
UAT_FILENAME_CB_DEF(rsa_privkeys_uats, uri, rsa_privkey_record_t)
UAT_CSTRING_CB_DEF(rsa_privkeys_uats, password, rsa_privkey_record_t)
static void *
uat_rsa_privkey_copy_str_cb(void *dest, const void *source, size_t len _U_)
{
rsa_privkey_record_t *d = (rsa_privkey_record_t *)dest;
const rsa_privkey_record_t *s = (const rsa_privkey_record_t *)source;
d->uri = g_strdup(s->uri);
d->password = g_strdup(s->password);
return dest;
}
static void
uat_rsa_privkey_free_str_cb(void *record)
{
rsa_privkey_record_t *rec = (rsa_privkey_record_t *)record;
g_free(rec->uri);
g_free(rec->password);
}
static void
load_rsa_keyfile(const char *filename, const char *password, gboolean save_key, char **err)
{
gnutls_x509_privkey_t x509_priv_key;
gnutls_privkey_t privkey = NULL;
char *errmsg = NULL;
int ret;
cert_key_id_t key_id;
size_t size = sizeof(key_id);
FILE *fp = ws_fopen(filename, "rb");
if (!fp) {
*err = g_strdup_printf("Error loading RSA key file %s: %s", filename, g_strerror(errno));
return;
}
if (!password || !password[0]) {
x509_priv_key = rsa_load_pem_key(fp, &errmsg);
} else {
/* Assume encrypted PKCS #12 container. */
x509_priv_key = rsa_load_pkcs12(fp, password, &errmsg);
}
fclose(fp);
if (!x509_priv_key) {
*err = g_strdup_printf("Error loading RSA key file %s: %s", filename, errmsg);
g_free(errmsg);
return;
}
gnutls_privkey_init(&privkey);
ret = gnutls_privkey_import_x509(privkey, x509_priv_key,
GNUTLS_PRIVKEY_IMPORT_AUTO_RELEASE|GNUTLS_PRIVKEY_IMPORT_COPY);
if (ret < 0) {
*err = g_strdup_printf("Error importing private key %s: %s", filename, gnutls_strerror(ret));
goto end;
}
ret = gnutls_x509_privkey_get_key_id(x509_priv_key, GNUTLS_KEYID_USE_SHA1, key_id.key_id, &size);
if (ret < 0 || size != sizeof(key_id)) {
*err = g_strdup_printf("Error calculating Key ID for %s: %s", filename, gnutls_strerror(ret));
goto end;
}
/* Remember the private key. */
if (save_key) {
rsa_privkey_add(&key_id, privkey);
privkey = NULL;
}
end:
gnutls_x509_privkey_deinit(x509_priv_key);
gnutls_privkey_deinit(privkey);
}
static void
uat_rsa_privkeys_post_update(void)
{
/* Clear previous keys. */
g_hash_table_remove_all(rsa_privkeys);
#ifdef HAVE_GNUTLS_PKCS11
g_slist_free_full(rsa_privkeys_pkcs11_pins, g_free);
rsa_privkeys_pkcs11_pins = NULL;
#endif /* HAVE_GNUTLS_PKCS11 */
GString *errors = NULL;
for (guint i = 0; i < uat_num_rsa_privkeys; i++) {
const rsa_privkey_record_t *rec = &uat_rsa_privkeys[i];
const char *token_uri = rec->uri;
char *err = NULL;
if (g_str_has_prefix(token_uri, "pkcs11:")) {
#ifdef HAVE_GNUTLS_PKCS11
pkcs11_load_keys_from_token(token_uri, rec->password, &err);
#endif /* HAVE_GNUTLS_PKCS11 */
} else {
load_rsa_keyfile(token_uri, rec->password, TRUE, &err);
}
if (err) {
if (!errors) {
errors = g_string_new("Error processing rsa_privkeys:");
}
g_string_append_c(errors, '\n');
g_string_append(errors, err);
g_free(err);
}
}
if (errors) {
report_failure("%s", errors->str);
g_string_free(errors, TRUE);
}
}
GSList *
secrets_get_available_keys(void)
{
GSList *keys = NULL;
#ifdef HAVE_GNUTLS_PKCS11
keys = g_slist_concat(keys, get_pkcs11_token_uris());
#endif
return keys;
}
gboolean
secrets_verify_key(const char *uri, const char *password, gboolean *need_password, char **error)
{
if (need_password) {
*need_password = FALSE;
}
if (error) {
*error = NULL;
}
if (g_str_has_prefix(uri, "pkcs11:")) {
#ifdef HAVE_GNUTLS_PKCS11
return verify_pkcs11_token(uri, password, need_password, error);
#else
if (error) {
*error = g_strdup("PKCS #11 support is not available in this build");
}
return FALSE;
#endif
} else if (g_file_test(uri, G_FILE_TEST_IS_REGULAR)) {
gchar *err = NULL;
load_rsa_keyfile(uri, password, FALSE, &err);
if (need_password) {
// Assume that failure to load the key is due to password errors.
// This might not be correct, but fixing this needs more changes.
*need_password = err != NULL;
}
if (err) {
if (error) {
*error = err;
} else {
g_free(err);
}
return FALSE;
}
return TRUE;
} else {
if (error) {
*error = g_strdup("Unsupported key URI or path");
}
return FALSE;
}
}
/**
* Register the UAT definitions such that settings can be loaded from file.
* Note: relies on uat_load_all to invoke the post_update_cb in order of
* registration below such that libraries are loaded *before* keys are read.
*/
static void
register_rsa_uats(void)
{
#ifdef HAVE_GNUTLS_PKCS11
static uat_field_t uat_pkcs11_libs_fields[] = {
UAT_FLD_FILENAME_OTHER(pkcs11_libs_uats, library_path, "Library Path", NULL, "PKCS #11 provider library file"),
UAT_END_FIELDS
};
pkcs11_libs_uat = uat_new("PKCS #11 Provider Libraries",
sizeof(pkcs11_lib_record_t),
"pkcs11_libs", /* filename */
FALSE, /* from_profile */
&uat_pkcs11_libs, /* data_ptr */
&uat_num_pkcs11_libs, /* numitems_ptr */
0, /* does not directly affect dissection */
NULL, /* Help section (currently a wiki page) */
uat_pkcs11_lib_copy_str_cb, /* copy_cb */
NULL, /* update_cb */
uat_pkcs11_lib_free_str_cb, /* free_cb */
uat_pkcs11_libs_load_all, /* post_update_cb */
NULL, /* reset_cb */
uat_pkcs11_libs_fields);
#endif /* HAVE_GNUTLS_PKCS11 */
static uat_field_t uat_rsa_privkeys_fields[] = {
UAT_FLD_FILENAME_OTHER(rsa_privkeys_uats, uri, "Keyfile or Token URI", NULL, "RSA Key File or PKCS #11 URI for token"),
UAT_FLD_FILENAME_OTHER(rsa_privkeys_uats, password, "Password", NULL, "RSA Key File password or PKCS #11 Token PIN"),
UAT_END_FIELDS
};
rsa_privkeys_uat = uat_new("RSA Private Keys",
sizeof(rsa_privkey_record_t),
"rsa_keys", /* filename */
FALSE, /* from_profile */
&uat_rsa_privkeys, /* data_ptr */
&uat_num_rsa_privkeys, /* numitems_ptr */
0, /* does not directly affect dissection */
NULL, /* Help section (currently a wiki page) */
uat_rsa_privkey_copy_str_cb, /* copy_cb */
NULL, /* update_cb */
uat_rsa_privkey_free_str_cb, /* free_cb */
uat_rsa_privkeys_post_update, /* post_update_cb */
NULL, /* reset_cb */
uat_rsa_privkeys_fields);
}
int
secrets_rsa_decrypt(const cert_key_id_t *key_id, const guint8 *encr, int encr_len, guint8 **out, int *out_len)
{
gboolean ret;
gnutls_datum_t ciphertext = { (guchar *)encr, encr_len };
gnutls_datum_t plain = { 0 };
gnutls_privkey_t pkey = (gnutls_privkey_t)g_hash_table_lookup(rsa_privkeys, key_id->key_id);
if (!pkey) {
return GNUTLS_E_NO_CERTIFICATE_FOUND;
}
ret = gnutls_privkey_decrypt_data(pkey, 0, &ciphertext, &plain);
if (ret == 0) {
*out = (guint8 *)g_memdup2(plain.data, plain.size);
*out_len = plain.size;
gnutls_free(plain.data);
}
return ret;
}
#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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