openssh-portable/ssh-ed25519-sk.c

289 lines
7.6 KiB
C

/* $OpenBSD: ssh-ed25519-sk.c,v 1.15 2022/10/28 00:44:44 djm Exp $ */
/*
* Copyright (c) 2019 Markus Friedl. All rights reserved.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* #define DEBUG_SK 1 */
#include "includes.h"
#define SSHKEY_INTERNAL
#include <sys/types.h>
#include <limits.h>
#include "crypto_api.h"
#include <string.h>
#include <stdarg.h>
#include "log.h"
#include "sshbuf.h"
#include "sshkey.h"
#include "ssherr.h"
#include "ssh.h"
#include "digest.h"
/* Reuse some ED25519 internals */
extern struct sshkey_impl_funcs sshkey_ed25519_funcs;
static void
ssh_ed25519_sk_cleanup(struct sshkey *k)
{
sshkey_sk_cleanup(k);
sshkey_ed25519_funcs.cleanup(k);
}
static int
ssh_ed25519_sk_equal(const struct sshkey *a, const struct sshkey *b)
{
if (!sshkey_sk_fields_equal(a, b))
return 0;
if (!sshkey_ed25519_funcs.equal(a, b))
return 0;
return 1;
}
static int
ssh_ed25519_sk_serialize_public(const struct sshkey *key, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
int r;
if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
return r;
if ((r = sshkey_serialize_sk(key, b)) != 0)
return r;
return 0;
}
static int
ssh_ed25519_sk_serialize_private(const struct sshkey *key, struct sshbuf *b,
enum sshkey_serialize_rep opts)
{
int r;
if ((r = sshkey_ed25519_funcs.serialize_public(key, b, opts)) != 0)
return r;
if ((r = sshkey_serialize_private_sk(key, b)) != 0)
return r;
return 0;
}
static int
ssh_ed25519_sk_copy_public(const struct sshkey *from, struct sshkey *to)
{
int r;
if ((r = sshkey_ed25519_funcs.copy_public(from, to)) != 0)
return r;
if ((r = sshkey_copy_public_sk(from, to)) != 0)
return r;
return 0;
}
static int
ssh_ed25519_sk_deserialize_public(const char *ktype, struct sshbuf *b,
struct sshkey *key)
{
int r;
if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
return r;
if ((r = sshkey_deserialize_sk(b, key)) != 0)
return r;
return 0;
}
static int
ssh_ed25519_sk_deserialize_private(const char *ktype, struct sshbuf *b,
struct sshkey *key)
{
int r;
if ((r = sshkey_ed25519_funcs.deserialize_public(ktype, b, key)) != 0)
return r;
if ((r = sshkey_private_deserialize_sk(b, key)) != 0)
return r;
return 0;
}
static int
ssh_ed25519_sk_verify(const struct sshkey *key,
const u_char *sig, size_t siglen,
const u_char *data, size_t dlen, const char *alg, u_int compat,
struct sshkey_sig_details **detailsp)
{
struct sshbuf *b = NULL;
struct sshbuf *encoded = NULL;
char *ktype = NULL;
const u_char *sigblob;
const u_char *sm;
u_char *m = NULL;
u_char apphash[32];
u_char msghash[32];
u_char sig_flags;
u_int sig_counter;
size_t len;
unsigned long long smlen = 0, mlen = 0;
int r = SSH_ERR_INTERNAL_ERROR;
int ret;
struct sshkey_sig_details *details = NULL;
if (detailsp != NULL)
*detailsp = NULL;
if (key == NULL ||
sshkey_type_plain(key->type) != KEY_ED25519_SK ||
key->ed25519_pk == NULL ||
sig == NULL || siglen == 0)
return SSH_ERR_INVALID_ARGUMENT;
if ((b = sshbuf_from(sig, siglen)) == NULL)
return SSH_ERR_ALLOC_FAIL;
if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
sshbuf_get_string_direct(b, &sigblob, &len) != 0 ||
sshbuf_get_u8(b, &sig_flags) != 0 ||
sshbuf_get_u32(b, &sig_counter) != 0) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
#ifdef DEBUG_SK
fprintf(stderr, "%s: data:\n", __func__);
/* sshbuf_dump_data(data, datalen, stderr); */
fprintf(stderr, "%s: sigblob:\n", __func__);
sshbuf_dump_data(sigblob, len, stderr);
fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
__func__, sig_flags, sig_counter);
#endif
if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
r = SSH_ERR_KEY_TYPE_MISMATCH;
goto out;
}
if (sshbuf_len(b) != 0) {
r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
goto out;
}
if (len > crypto_sign_ed25519_BYTES) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if (ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
strlen(key->sk_application), apphash, sizeof(apphash)) != 0 ||
ssh_digest_memory(SSH_DIGEST_SHA256, data, dlen,
msghash, sizeof(msghash)) != 0) {
r = SSH_ERR_INVALID_ARGUMENT;
goto out;
}
#ifdef DEBUG_SK
fprintf(stderr, "%s: hashed application:\n", __func__);
sshbuf_dump_data(apphash, sizeof(apphash), stderr);
fprintf(stderr, "%s: hashed message:\n", __func__);
sshbuf_dump_data(msghash, sizeof(msghash), stderr);
#endif
if ((details = calloc(1, sizeof(*details))) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
details->sk_counter = sig_counter;
details->sk_flags = sig_flags;
if ((encoded = sshbuf_new()) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if (sshbuf_put(encoded, sigblob, len) != 0 ||
sshbuf_put(encoded, apphash, sizeof(apphash)) != 0 ||
sshbuf_put_u8(encoded, sig_flags) != 0 ||
sshbuf_put_u32(encoded, sig_counter) != 0 ||
sshbuf_put(encoded, msghash, sizeof(msghash)) != 0) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
#ifdef DEBUG_SK
fprintf(stderr, "%s: signed buf:\n", __func__);
sshbuf_dump(encoded, stderr);
#endif
sm = sshbuf_ptr(encoded);
smlen = sshbuf_len(encoded);
mlen = smlen;
if ((m = malloc(smlen)) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
key->ed25519_pk)) != 0) {
debug2_f("crypto_sign_ed25519_open failed: %d", ret);
}
if (ret != 0 || mlen != smlen - len) {
r = SSH_ERR_SIGNATURE_INVALID;
goto out;
}
/* XXX compare 'm' and 'sm + len' ? */
/* success */
r = 0;
if (detailsp != NULL) {
*detailsp = details;
details = NULL;
}
out:
if (m != NULL)
freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
sshkey_sig_details_free(details);
sshbuf_free(b);
sshbuf_free(encoded);
free(ktype);
return r;
}
static const struct sshkey_impl_funcs sshkey_ed25519_sk_funcs = {
/* .size = */ NULL,
/* .alloc = */ NULL,
/* .cleanup = */ ssh_ed25519_sk_cleanup,
/* .equal = */ ssh_ed25519_sk_equal,
/* .ssh_serialize_public = */ ssh_ed25519_sk_serialize_public,
/* .ssh_deserialize_public = */ ssh_ed25519_sk_deserialize_public,
/* .ssh_serialize_private = */ ssh_ed25519_sk_serialize_private,
/* .ssh_deserialize_private = */ ssh_ed25519_sk_deserialize_private,
/* .generate = */ NULL,
/* .copy_public = */ ssh_ed25519_sk_copy_public,
/* .sign = */ NULL,
/* .verify = */ ssh_ed25519_sk_verify,
};
const struct sshkey_impl sshkey_ed25519_sk_impl = {
/* .name = */ "sk-ssh-ed25519@openssh.com",
/* .shortname = */ "ED25519-SK",
/* .sigalg = */ NULL,
/* .type = */ KEY_ED25519_SK,
/* .nid = */ 0,
/* .cert = */ 0,
/* .sigonly = */ 0,
/* .keybits = */ 256,
/* .funcs = */ &sshkey_ed25519_sk_funcs,
};
const struct sshkey_impl sshkey_ed25519_sk_cert_impl = {
/* .name = */ "sk-ssh-ed25519-cert-v01@openssh.com",
/* .shortname = */ "ED25519-SK-CERT",
/* .sigalg = */ NULL,
/* .type = */ KEY_ED25519_SK_CERT,
/* .nid = */ 0,
/* .cert = */ 1,
/* .sigonly = */ 0,
/* .keybits = */ 256,
/* .funcs = */ &sshkey_ed25519_sk_funcs,
};