Fix GSS KEX causing ssh failures when connecting to WinSSHD
Resolves: RHEL-5321
This commit is contained in:
Dmitry Belyavskiy
parent
6242770aa2
commit
6c888396c9
@ -1509,7 +1509,7 @@ new file mode 100644
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index 00000000..0b2f6a56
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--- /dev/null
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+++ b/kexgssc.c
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@@ -0,0 +1,595 @@
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@@ -0,0 +1,618 @@
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+/*
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+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
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+ *
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@ -1571,7 +1571,7 @@ index 00000000..0b2f6a56
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+ struct sshbuf *server_blob = NULL;
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+ struct sshbuf *shared_secret = NULL;
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+ struct sshbuf *server_host_key_blob = NULL;
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+ struct sshbuf *empty = sshbuf_new();
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+ struct sshbuf *empty = NULL;
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+ u_char *msg;
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+ int type = 0;
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+ int first = 1;
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@ -1610,8 +1610,10 @@ index 00000000..0b2f6a56
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+ default:
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+ fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
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+ }
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+ if (r != 0)
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+ if (r != 0) {
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+ ssh_gssapi_delete_ctx(&ctxt);
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+ return r;
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+ }
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+
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+ token_ptr = GSS_C_NO_BUFFER;
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+
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@ -1674,11 +1676,16 @@ index 00000000..0b2f6a56
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+ do {
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+ type = ssh_packet_read(ssh);
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+ if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
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+ char *tmp = NULL;
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+ size_t tmp_len = 0;
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+
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+ debug("Received KEXGSS_HOSTKEY");
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+ if (server_host_key_blob)
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+ fatal("Server host key received more than once");
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+ if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
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+ if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0)
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+ fatal("Failed to read server host key: %s", ssh_err(r));
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+ if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL)
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+ fatal("sshbuf_from failed");
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+ }
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+ } while (type == SSH2_MSG_KEXGSS_HOSTKEY);
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+
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@ -1779,6 +1786,11 @@ index 00000000..0b2f6a56
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+ if (r != 0)
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+ goto out;
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+
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+ if ((empty = sshbuf_new()) == NULL) {
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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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+ hashlen = sizeof(hash);
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+ if ((r = kex_gen_hash(
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+ kex->hash_alg,
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@ -1848,7 +1860,7 @@ index 00000000..0b2f6a56
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+ size_t hashlen;
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+ const BIGNUM *pub_key, *dh_p, *dh_g;
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+ int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
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+ struct sshbuf *empty = sshbuf_new();
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+ struct sshbuf *empty = NULL;
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+ u_char c;
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+ int r;
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+
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@ -1960,11 +1972,16 @@ index 00000000..0b2f6a56
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+ do {
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+ type = ssh_packet_read(ssh);
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+ if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
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+ char *tmp = NULL;
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+ size_t tmp_len = 0;
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+
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+ debug("Received KEXGSS_HOSTKEY");
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+ if (server_host_key_blob)
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+ fatal("Server host key received more than once");
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+ if ((r = sshpkt_getb_froms(ssh, &server_host_key_blob)) != 0)
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+ if ((r = sshpkt_get_string(ssh, &tmp, &tmp_len)) != 0)
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+ fatal("sshpkt failed: %s", ssh_err(r));
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+ if ((server_host_key_blob = sshbuf_from(tmp, tmp_len)) == NULL)
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+ fatal("sshbuf_from failed");
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+ }
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+ } while (type == SSH2_MSG_KEXGSS_HOSTKEY);
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+
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@ -2040,6 +2057,7 @@ index 00000000..0b2f6a56
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+ (r = sshbuf_get_bignum2(buf, &dh_server_pub)) != 0)
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+ goto out;
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+ sshbuf_free(buf);
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+ buf = NULL;
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+
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+ if ((shared_secret = sshbuf_new()) == NULL) {
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+ r = SSH_ERR_ALLOC_FAIL;
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@ -2048,6 +2066,10 @@ index 00000000..0b2f6a56
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+
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+ if ((r = kex_dh_compute_key(kex, dh_server_pub, shared_secret)) != 0)
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+ goto out;
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+ if ((empty = sshbuf_new()) == NULL) {
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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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+ DH_get0_pqg(kex->dh, &dh_p, NULL, &dh_g);
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+ hashlen = sizeof(hash);
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@ -2094,6 +2116,7 @@ index 00000000..0b2f6a56
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+ if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
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+ r = kex_send_newkeys(ssh);
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+out:
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+ sshbuf_free(buf);
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+ sshbuf_free(server_blob);
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+ sshbuf_free(empty);
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+ explicit_bzero(hash, sizeof(hash));
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@ -2110,7 +2133,7 @@ new file mode 100644
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index 00000000..60bc02de
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--- /dev/null
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+++ b/kexgsss.c
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@@ -0,0 +1,474 @@
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@@ -0,0 +1,482 @@
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+/*
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+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
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+ *
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@ -2177,7 +2200,7 @@ index 00000000..60bc02de
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+ */
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+
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+ OM_uint32 ret_flags = 0;
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+ gss_buffer_desc gssbuf, recv_tok, msg_tok;
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+ gss_buffer_desc gssbuf = {0, NULL}, recv_tok, msg_tok;
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+ gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
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+ Gssctxt *ctxt = NULL;
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+ struct sshbuf *shared_secret = NULL;
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@ -2217,7 +2240,7 @@ index 00000000..60bc02de
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+ type = ssh_packet_read(ssh);
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+ switch(type) {
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+ case SSH2_MSG_KEXGSS_INIT:
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+ if (client_pubkey != NULL)
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+ if (gssbuf.value != NULL)
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+ fatal("Received KEXGSS_INIT after initialising");
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+ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
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+ &recv_tok)) != 0 ||
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@ -2248,6 +2271,31 @@ index 00000000..60bc02de
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+ goto out;
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+
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+ /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
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+
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+ /* Calculate the hash early so we can free the
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+ * client_pubkey, which has reference to the parent
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+ * buffer state->incoming_packet
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+ */
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+ hashlen = sizeof(hash);
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+ if ((r = kex_gen_hash(
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+ kex->hash_alg,
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+ kex->client_version,
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+ kex->server_version,
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+ kex->peer,
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+ kex->my,
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+ empty,
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+ client_pubkey,
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+ server_pubkey,
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+ shared_secret,
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+ hash, &hashlen)) != 0)
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+ goto out;
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+
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+ gssbuf.value = hash;
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+ gssbuf.length = hashlen;
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+
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+ sshbuf_free(client_pubkey);
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+ client_pubkey = NULL;
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+
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+ break;
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+ case SSH2_MSG_KEXGSS_CONTINUE:
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+ if ((r = ssh_gssapi_sshpkt_get_buffer_desc(ssh,
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@ -2269,7 +2317,7 @@ index 00000000..60bc02de
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+ if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
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+ fatal("Zero length token output when incomplete");
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+
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+ if (client_pubkey == NULL)
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+ if (gssbuf.value == NULL)
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+ fatal("No client public key");
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+
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+ if (maj_status & GSS_S_CONTINUE_NEEDED) {
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@ -2298,23 +2346,6 @@ index 00000000..60bc02de
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+ if (!(ret_flags & GSS_C_INTEG_FLAG))
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+ fatal("Integrity flag wasn't set");
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+
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+ hashlen = sizeof(hash);
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+ if ((r = kex_gen_hash(
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+ kex->hash_alg,
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+ kex->client_version,
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+ kex->server_version,
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+ kex->peer,
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+ kex->my,
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+ empty,
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+ client_pubkey,
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+ server_pubkey,
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+ shared_secret,
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+ hash, &hashlen)) != 0)
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+ goto out;
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+
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+ gssbuf.value = hash;
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+ gssbuf.length = hashlen;
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+
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+ if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt, &gssbuf, &msg_tok))))
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+ fatal("Couldn't get MIC");
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+
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@ -826,6 +826,8 @@ getent passwd sshd >/dev/null || \
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Resolves: RHEL-5279
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- Using DigestSign/DigestVerify functions for better FIPS compatibility
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Resolves: RHEL-5217
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- Fix GSS KEX causing ssh failures when connecting to WinSSHD
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Resolves: RHEL-5321
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* Thu Aug 24 2023 Dmitry Belyavskiy <dbelyavs@redhat.com> - 8.0p1-19
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- rebuilt
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