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/*
* Algorithm lookup, for libreswan
*
* Copyright (C) 2017-2019 Andrew Cagney <cagney@gnu.org>
*
* 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 2 of the License, or (at your
* option) any later version. See <https://www.gnu.org/licenses/gpl2.txt>.
*
* 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.
*/
#include <stdlib.h>
#include "lswlog.h"
#include "proposals.h"
#include "alg_byname.h"
#include "ike_alg.h"
#include "impair.h"
bool alg_byname_ok(struct proposal_parser *parser,
const struct ike_alg *alg, shunk_t print_name)
{
const struct proposal_protocol *protocol = parser->protocol;
const struct proposal_policy *policy = parser->policy;
if (alg->id[protocol->alg_id] < 0) {
enum_buf vb;
proposal_error(parser, "%s %s algorithm '"PRI_SHUNK"' is not supported by %s",
protocol->name, ike_alg_type_name(alg->algo_type),
pri_shunk(print_name),
str_enum(&ike_version_names, policy->version, &vb));
return false;
}
/*
* According to parser policy, is the algorithm "implemented"?
*
* For IKE, this checks things like an in-process
* implementation being present. For ESP/AH this checks that
* it is is implemented in the kernel (well except for DH
* which is still requires an in-process implementation).
*/
passert(policy->alg_is_ok != NULL);
if (!policy->alg_is_ok(alg)) {
proposal_error(parser, "%s %s algorithm '"PRI_SHUNK"' is not supported",
protocol->name, ike_alg_type_name(alg->algo_type),
pri_shunk(print_name));
return false;
}
/*
* Check that the algorithm is valid.
*
* FIPS, for instance, will invalidate some algorithms during
* startup.
*
* Since it likely involves a lookup, it is left until last.
*/
if (!ike_alg_is_valid(alg)) {
proposal_error(parser, "%s %s algorithm '"PRI_SHUNK"' is not valid",
protocol->name, ike_alg_type_name(alg->algo_type),
pri_shunk(print_name));
return false;
}
return true;
}
const struct ike_alg *alg_byname(struct proposal_parser *parser,
const struct ike_alg_type *type,
shunk_t name, shunk_t print_name)
{
struct logger *logger = parser->policy->logger;
passert(parser->diag == NULL);
const struct proposal_protocol *protocol = parser->protocol;
const struct ike_alg *alg = ike_alg_byname(type, name);
if (alg == NULL) {
/*
* Known at all? Poke around in the enum tables to
* see if it turns up.
*/
if (ike_alg_enum_matched(type, name)) {
proposal_error(parser, "%s %s algorithm '"PRI_SHUNK"' is not supported",
protocol->name, ike_alg_type_name(type),
pri_shunk(print_name));
} else {
proposal_error(parser, "%s %s algorithm '"PRI_SHUNK"' is not recognized",
protocol->name, ike_alg_type_name(type),
pri_shunk(print_name));
}
passert(parser->diag != NULL);
ldbgf(DBG_PROPOSAL_PARSER, logger,
"ike_alg_byname() failed: %s",
str_diag(parser->diag));
return NULL;
}
/*
* Does it pass muster?
*/
if (!alg_byname_ok(parser, alg, print_name)) {
passert(parser->diag != NULL);
ldbgf(DBG_PROPOSAL_PARSER, logger,
"alg_byname_ok() failed: %s",
str_diag(parser->diag));
return NULL;
}
return alg;
}
const struct ike_alg *encrypt_alg_byname(struct proposal_parser *parser,
shunk_t name, size_t key_bit_length,
shunk_t print_name)
{
const struct ike_alg *alg = alg_byname(parser, IKE_ALG_ENCRYPT, name,
print_name);
if (alg == NULL) {
return NULL;
}
const struct encrypt_desc *encrypt = encrypt_desc(alg);
if (!impair.send_key_size_check && key_bit_length > 0) {
if (encrypt->keylen_omitted) {
proposal_error(parser, "%s encryption algorithm %s does not allow a key lengths",
parser->protocol->name,
encrypt->common.fqn);
if (!impair_proposal_errors(parser)) {
return NULL;
}
}
if (!encrypt_has_key_bit_length(encrypt, key_bit_length)) {
JAMBUF(buf) {
jam(buf, "%s encryption algorithm %s with key length %zu invalid; valid key lengths:",
parser->protocol->name,
encrypt->common.fqn,
key_bit_length);
/* reverse: table in descending order with trailing zeros */
const char *sep = " ";
for (int i = elemsof(encrypt->key_bit_lengths) - 1; i >= 0; i--) {
if (encrypt->key_bit_lengths[i] > 0) {
jam(buf, "%s%d", sep, encrypt->key_bit_lengths[i]);
sep = ", ";
}
}
proposal_error(parser, PRI_SHUNK, pri_shunk(jambuf_as_shunk(buf)));
}
if (!impair_proposal_errors(parser)) {
return NULL;
}
}
}
return alg;
}
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