/* $OpenBSD: digest-openssl.c,v 1.9 2020/10/29 02:52:43 djm Exp $ */
/*
 * Copyright (c) 2013 Damien Miller <djm@mindrot.org>
 * Copyright (c) 2018-2026 Roumen Petrov.  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.
 */

#include "includes.h"

#ifdef WITH_OPENSSL

#include <sys/types.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/evp.h>
#include <openssl/err.h>

#include "evp-compat.h"
#include "sshbuf.h"
#include "digest.h"
#include "ssherr.h"

#ifdef ENABLE_KEY_PROVIDERS
extern OSSL_LIB_CTX *pkixssh_libctx;
extern char *pkixssh_propq;
#endif


#ifndef HAVE_EVP_SHA256
# define EVP_sha256 NULL
#endif
#ifndef HAVE_EVP_SHA384
# define EVP_sha384 NULL
#endif
#ifndef HAVE_EVP_SHA512
# define EVP_sha512 NULL
#endif

struct ssh_digest_ctx {
	int alg;
	EVP_MD_CTX *mdctx;
};

struct ssh_digest {
	int id;
	const char *name;
	size_t digest_len;
	const EVP_MD *(*mdfunc)(void);
	int enabled;
};

/* NB. Indexed directly by algorithm number */
static struct ssh_digest digests[] = {
	{ SSH_DIGEST_MD5,	"MD5",		16,	EVP_md5, -1 },
	{ SSH_DIGEST_SHA1,	"SHA1",		20,	EVP_sha1, -1 },
	{ SSH_DIGEST_SHA256,	"SHA256",	32,	EVP_sha256, -1 },
	{ SSH_DIGEST_SHA384,	"SHA384",	48,	EVP_sha384, -1 },
	{ SSH_DIGEST_SHA512,	"SHA512",	64,	EVP_sha512, -1 },
	{ -1,			NULL,		0,	NULL, 0 },
};

static const struct ssh_digest *
ssh_digest_by_alg(int alg)
{
	struct ssh_digest *d;

	if (alg < 0 || alg >= SSH_DIGEST_MAX)
		return NULL;
	d = &digests[alg];
	if (d->id != alg) /* sanity */
		return NULL;
	if (d->mdfunc == NULL)
		return NULL;

	if (d->enabled != -1)
		goto done;

#ifdef HAVE_FIPS_MODULE
#ifdef ENABLE_KEY_PROVIDERS
	switch (alg) {
	case SSH_DIGEST_MD5: {
		/* OpenSSL FIPS provider offers MD5, but operations fail =>
		 * unconditionally exclude digest.
		 */
		d->enabled = !ssh_is_fips_provider();
		goto done;
		} break;
	}
#endif
	if (ssh_is_fips_enabled()) {
	/* The FIPS flag has no effect for providers */
	#ifdef ENABLE_KEY_PROVIDERS
	{	EVP_MD *md;
		ERR_set_mark();
		md = EVP_MD_fetch(pkixssh_libctx, d->name, pkixssh_propq);
		if (md == NULL) return NULL;
		/* clear needless errors for unsupported algorithms */
		ERR_pop_to_mark();
		d->enabled = (md != NULL) ? 1 : 0;
		EVP_MD_free(md);
	}
	#else
	{	const EVP_MD *md = d->mdfunc();
		d->enabled = (EVP_MD_flags(md) & EVP_MD_FLAG_FIPS) ? 1 : 0;
	}
	#endif
	}
#endif /*def HAVE_FIPS_MODULE*/

done:
	return d->enabled ? d : NULL;
}

int
ssh_digest_alg_by_name(const char *name)
{
	int alg;

	for (alg = 0; digests[alg].id != -1; alg++) {
		if (strcasecmp(name, digests[alg].name) == 0)
			return digests[alg].id;
	}
	return -1;
}

const char *
ssh_digest_alg_name(int alg)
{
	const struct ssh_digest *digest = ssh_digest_by_alg(alg);

	return digest == NULL ? NULL : digest->name;
}

size_t
ssh_digest_bytes(int alg)
{
	const struct ssh_digest *digest = ssh_digest_by_alg(alg);

	return digest == NULL ? 0 : digest->digest_len;
}

int
ssh_digest_maxbytes(void) {
	int k;

	/*NOTE digest table is sorted in ascending order by digest length*/
	for (k = SSH_DIGEST_MAX - 1; k >= 0; k--) {
		const struct ssh_digest *d = ssh_digest_by_alg(k);
		if (d == NULL) continue;
		return digests[k].id;
	}
	return -1;
}

size_t
ssh_digest_blocksize(struct ssh_digest_ctx *ctx)
{
	return EVP_MD_CTX_block_size(ctx->mdctx);
}

struct ssh_digest_ctx *
ssh_digest_start(int alg)
{
	const struct ssh_digest *digest = ssh_digest_by_alg(alg);
	struct ssh_digest_ctx *ret;

	if (digest == NULL || ((ret = calloc(1, sizeof(*ret))) == NULL))
		return NULL;
	ret->alg = alg;
	if ((ret->mdctx = EVP_MD_CTX_new()) == NULL) {
		free(ret);
		return NULL;
	}
	if (EVP_DigestInit_ex(ret->mdctx, digest->mdfunc(), NULL) != 1) {
		ssh_digest_free(ret);
		return NULL;
	}
	return ret;
}

int
ssh_digest_copy_state(struct ssh_digest_ctx *from, struct ssh_digest_ctx *to)
{
	if (from->alg != to->alg)
		return SSH_ERR_INVALID_ARGUMENT;
	if (!EVP_MD_CTX_copy_ex(to->mdctx, from->mdctx))
		return SSH_ERR_LIBCRYPTO_ERROR;
	return 0;
}

int
ssh_digest_update(struct ssh_digest_ctx *ctx, const void *m, size_t mlen)
{
	if (EVP_DigestUpdate(ctx->mdctx, m, mlen) != 1)
		return SSH_ERR_LIBCRYPTO_ERROR;
	return 0;
}

int
ssh_digest_update_buffer(struct ssh_digest_ctx *ctx, const struct sshbuf *b)
{
	return ssh_digest_update(ctx, sshbuf_ptr(b), sshbuf_len(b));
}

int
ssh_digest_final(struct ssh_digest_ctx *ctx, u_char *d, size_t dlen)
{
	const struct ssh_digest *digest = ssh_digest_by_alg(ctx->alg);
	u_int l = dlen;

	if (digest == NULL || dlen > UINT_MAX)
		return SSH_ERR_INVALID_ARGUMENT;
	if (dlen < digest->digest_len) /* No truncation allowed */
		return SSH_ERR_INVALID_ARGUMENT;
	if (EVP_DigestFinal_ex(ctx->mdctx, d, &l) != 1)
		return SSH_ERR_LIBCRYPTO_ERROR;
	if (l != digest->digest_len) /* sanity */
		return SSH_ERR_INTERNAL_ERROR;
	return 0;
}

void
ssh_digest_free(struct ssh_digest_ctx *ctx)
{
	if (ctx == NULL)
		return;
	EVP_MD_CTX_free(ctx->mdctx);
	freezero(ctx, sizeof(*ctx));
}

int
ssh_digest_memory(int alg, const void *m, size_t mlen, u_char *d, size_t dlen)
{
	const struct ssh_digest *digest = ssh_digest_by_alg(alg);
	u_int mdlen;

	if (digest == NULL)
		return SSH_ERR_INVALID_ARGUMENT;
	if (dlen > UINT_MAX)
		return SSH_ERR_INVALID_ARGUMENT;
	if (dlen < digest->digest_len)
		return SSH_ERR_INVALID_ARGUMENT;
	mdlen = dlen;
	if (!EVP_Digest(m, mlen, d, &mdlen, digest->mdfunc(), NULL))
		return SSH_ERR_LIBCRYPTO_ERROR;
	return 0;
}

int
ssh_digest_buffer(int alg, const struct sshbuf *b, u_char *d, size_t dlen)
{
	return ssh_digest_memory(alg, sshbuf_ptr(b), sshbuf_len(b), d, dlen);
}
#endif /* WITH_OPENSSL */
