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session: Refactor ssh_get_publickey_hash

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Make it use the one-shot API of hash functions,
and remove the FIPS restriction for OpenSSL 3.5+
where we can fetch the MD5 implementation from
a non-FIPS provider to use for non-crypto purposes.

Signed-off-by: Pavol Žáčik <pzacik@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Pavol Žáčik
2025-12-18 10:54:59 +01:00
committed by Jakub Jelen
parent 2c5bb17211
commit 3710b31d24
2 changed files with 36 additions and 108 deletions
Download Patch File Download Diff File Expand all files Collapse all files

123
src/session.c
View File

@@ -1300,7 +1300,7 @@ int ssh_get_publickey(ssh_session session, ssh_key *key)
*
* @param[in] hlen The length of the hash.
*
* @return 0 on success, -1 if an error occurred.
* @return SSH_OK on success, SSH_ERROR if an error occurred.
*
* @warning It is very important that you verify at some moment that the hash
* matches a known server. If you don't do it, cryptography won't help
@@ -1319,126 +1319,57 @@ int ssh_get_publickey_hash(const ssh_key key,
{
ssh_string blob = NULL;
unsigned char *h = NULL;
int rc;
int (*digest)(const unsigned char *, size_t, unsigned char *) = NULL;
int rc, ret = SSH_ERROR;
rc = ssh_pki_export_pubkey_blob(key, &blob);
if (rc < 0) {
return rc;
goto out;
}
switch (type) {
case SSH_PUBLICKEY_HASH_SHA1: {
SHACTX ctx = NULL;
h = calloc(1, SHA_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = sha1_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = sha1_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
sha1_ctx_free(ctx);
goto out;
}
rc = sha1_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
case SSH_PUBLICKEY_HASH_SHA1:
digest = sha1;
*hlen = SHA_DIGEST_LEN;
break;
}
case SSH_PUBLICKEY_HASH_SHA256: {
SHA256CTX ctx = NULL;
h = calloc(1, SHA256_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = sha256_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = sha256_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
sha256_ctx_free(ctx);
goto out;
}
rc = sha256_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
case SSH_PUBLICKEY_HASH_SHA256:
digest = sha256;
*hlen = SHA256_DIGEST_LEN;
break;
}
case SSH_PUBLICKEY_HASH_MD5: {
MD5CTX ctx = NULL;
/* In FIPS mode, we cannot use MD5 */
case SSH_PUBLICKEY_HASH_MD5:
#if defined(HAVE_LIBCRYPTO) && OPENSSL_VERSION_NUMBER < 0x30000000L
/* In FIPS mode without OpenSSL providers, we cannot use MD5 */
if (ssh_fips_mode()) {
SSH_LOG(SSH_LOG_TRACE,
"In FIPS mode MD5 is not allowed."
"Try using SSH_PUBLICKEY_HASH_SHA256");
rc = SSH_ERROR;
goto out;
}
h = calloc(1, MD5_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = md5_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = md5_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
md5_ctx_free(ctx);
goto out;
}
rc = md5_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
#endif
digest = md5;
*hlen = MD5_DIGEST_LEN;
break;
}
default:
rc = -1;
goto out;
}
h = calloc(1, *hlen);
if (h == NULL) {
goto out;
}
rc = digest(ssh_string_data(blob), ssh_string_len(blob), h);
if (rc != SSH_OK) {
free(h);
goto out;
}
*hash = h;
rc = 0;
ret = SSH_OK;
out:
SSH_STRING_FREE(blob);
return rc;
return ret;
}
/** @} */

21
tests/unittests/torture_hashes.c
View File

@@ -57,25 +57,22 @@ static void torture_md5_hash(void **state)
size_t hlen;
int rc = 0;
#if defined(HAVE_LIBCRYPTO) && OPENSSL_VERSION_NUMBER < 0x30000000L
/* In FIPS mode without OpenSSL providers, we cannot use MD5 */
if (ssh_fips_mode()) {
skip();
}
#endif
rc = ssh_get_publickey_hash(pubkey, SSH_PUBLICKEY_HASH_MD5,
(unsigned char **)&hash, &hlen);
if (ssh_fips_mode()) {
/* When in FIPS mode, expect the call to fail */
assert_int_equal(rc, SSH_ERROR);
} else {
assert_int_equal(rc, SSH_OK);
assert_int_equal(rc, SSH_OK);
hexa = ssh_get_hexa((unsigned char *)hash, hlen);
SSH_STRING_FREE_CHAR(hash);
assert_string_equal(hexa,
"50:15:a0:9b:92:bf:33:1c:01:c5:8c:fe:18:fa:ce:78");
SSH_STRING_FREE_CHAR(hexa);
}
hexa = ssh_get_hexa((unsigned char *)hash, hlen);
SSH_STRING_FREE_CHAR(hash);
assert_string_equal(hexa,
"50:15:a0:9b:92:bf:33:1c:01:c5:8c:fe:18:fa:ce:78");
SSH_STRING_FREE_CHAR(hexa);
}
static void torture_sha1_hash(void **state)