Marcus Meissner
3f6eda5c88
* No changes for askpass, see main package changelog for
details.
- Update to openssh 9.9p1:
= Future deprecation notice
* OpenSSH plans to remove support for the DSA signature algorithm
in early 2025. This release disables DSA by default at compile
time. DSA, as specified in the SSHv2 protocol, is inherently
weak - being limited to a 160 bit private key and use of the
SHA1 digest. Its estimated security level is only 80 bits
symmetric equivalent.
OpenSSH has disabled DSA keys by default since 2015 but has
retained run-time optional support for them. DSA was the only
mandatory-to-implement algorithm in the SSHv2 RFCs, mostly
because alternative algorithms were encumbered by patents when
the SSHv2 protocol was specified.
This has not been the case for decades at this point and better
algorithms are well supported by all actively-maintained SSH
implementations. We do not consider the costs of maintaining
DSA in OpenSSH to be justified and hope that removing it from
OpenSSH can accelerate its wider deprecation in supporting
cryptography libraries.
= Potentially-incompatible changes
* ssh(1): remove support for pre-authentication compression.
OpenSSH has only supported post-authentication compression in
the server for some years. Compression before authentication
significantly increases the attack surface of SSH servers and
risks creating oracles that reveal information about
information sent during authentication.
OBS-URL: https://build.opensuse.org/package/show/network/openssh?expand=0&rev=275
159 lines
3.8 KiB
Diff
159 lines
3.8 KiB
Diff
Index: openssh-8.8p1/kex.c
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===================================================================
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--- openssh-8.8p1.orig/kex.c
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+++ openssh-8.8p1/kex.c
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@@ -40,6 +40,7 @@
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#ifdef WITH_OPENSSL
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#include <openssl/crypto.h>
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#include <openssl/dh.h>
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+#include <openssl/kdf.h>
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#endif
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#include "ssh.h"
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@@ -1115,8 +1116,93 @@ kex_choose_conf(struct ssh *ssh)
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return r;
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}
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+#ifdef WITH_OPENSSL
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+
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+static const EVP_MD *
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+get_openssl_md_for_hash_alg (int hash_alg)
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+{
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+ if (hash_alg < 0 || hash_alg >= SSH_DIGEST_MAX)
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+ return NULL;
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+
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+ switch (hash_alg)
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+ {
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+ case SSH_DIGEST_MD5:
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+ return EVP_md5();
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+ case SSH_DIGEST_SHA1:
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+ return EVP_sha1();
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+ case SSH_DIGEST_SHA256:
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+ return EVP_sha256();
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+ case SSH_DIGEST_SHA384:
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+ return EVP_sha384();
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+ case SSH_DIGEST_SHA512:
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+ return EVP_sha512();
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+ default:
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+ break;
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+ }
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+
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+ return NULL;
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+}
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+
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static int
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-derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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+derive_key_via_openssl(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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+ const struct sshbuf *shared_secret, u_char **keyp)
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+{
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+ struct kex *kex = ssh->kex;
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+ EVP_KDF_CTX *hashctx = NULL;
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+ const EVP_MD *md = NULL;
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+ u_char *digest = NULL;
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+ int r = SSH_ERR_LIBCRYPTO_ERROR;
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+
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+ hashctx = EVP_KDF_CTX_new_id (EVP_KDF_SSHKDF);
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+ if (!hashctx)
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+ goto out;
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+
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+ md = get_openssl_md_for_hash_alg (kex->hash_alg);
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+ if (!md)
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+ goto out;
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+
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+ if (EVP_KDF_ctrl (hashctx, EVP_KDF_CTRL_SET_MD,
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+ md) != 1
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+ || EVP_KDF_ctrl (hashctx, EVP_KDF_CTRL_SET_KEY,
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+ sshbuf_ptr(shared_secret), sshbuf_len(shared_secret)) != 1
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+ || EVP_KDF_ctrl (hashctx, EVP_KDF_CTRL_SET_SSHKDF_TYPE,
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+ (int) id) != 1
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+ || EVP_KDF_ctrl (hashctx, EVP_KDF_CTRL_SET_SSHKDF_XCGHASH,
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+ hash, (size_t) hashlen) != 1
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+ || EVP_KDF_ctrl (hashctx, EVP_KDF_CTRL_SET_SSHKDF_SESSION_ID,
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+ sshbuf_ptr(kex->session_id),
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+ (size_t) sshbuf_len(kex->session_id)) != 1)
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+ goto out;
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+
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+ digest = calloc (1, need);
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+ if (!digest) {
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+ r = SSH_ERR_ALLOC_FAIL;
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+ goto out;
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+ }
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+
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+ if (EVP_KDF_derive (hashctx, digest, need) != 1)
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+ goto out;
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+
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+ *keyp = digest;
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+ digest = NULL;
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+ r = 0;
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+
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+ out:
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+ if (hashctx)
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+ EVP_KDF_CTX_free(hashctx);
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+
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+ if (digest)
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+ free(digest);
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+
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+ return r;
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+}
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+
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+#else
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+# error This version of openssh must be built with openssl to benefit from FIPS certification.
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+#endif
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+
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+static int
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+derive_key_via_internal(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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const struct sshbuf *shared_secret, u_char **keyp)
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{
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struct kex *kex = ssh->kex;
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@@ -1179,6 +1265,50 @@ derive_key(struct ssh *ssh, int id, u_in
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return r;
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}
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+/* Belt and suspenders; we want the output from openssl because it's FIPS certified. However,
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+ * if there's a bug in the implementation, we should not proceed. Minimize risk by requiring
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+ * the implementations agree. */
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+static int
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+derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
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+ const struct sshbuf *shared_secret, u_char **keyp)
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+{
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+#ifdef WITH_OPENSSL
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+
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+ u_char *buf_openssl = NULL, *buf_internal = NULL;
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+ int r;
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+
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+ r = derive_key_via_openssl (ssh, id, need, hash, hashlen, shared_secret, &buf_openssl);
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+ if (r != 0)
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+ goto out;
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+
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+ r = derive_key_via_internal (ssh, id, need, hash, hashlen, shared_secret, &buf_internal);
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+ if (r != 0)
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+ goto out;
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+
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+ if (memcmp (buf_openssl, buf_internal, need))
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+ {
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+ r = SSH_ERR_LIBCRYPTO_ERROR;
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+ goto out;
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+ }
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+
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+ *keyp = buf_openssl;
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+ buf_openssl = NULL;
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+
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+ out:
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+ if (buf_openssl)
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+ free (buf_openssl);
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+ if (buf_internal)
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+ free (buf_internal);
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+
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+ return r;
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+
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+#else
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+
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+ return derive_key_via_internal (ssh, id, need, hash, hashlen, shared_secret, keyp);
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+
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+#endif
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+}
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+
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#define NKEYS 6
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int
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kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
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