diff options
Diffstat (limited to 'kex.c')
| -rw-r--r-- | kex.c | 48 |
1 files changed, 45 insertions, 3 deletions
@@ -1,4 +1,4 @@ -/* $OpenBSD: kex.c,v 1.168 2021/04/03 06:18:40 djm Exp $ */ +/* $OpenBSD: kex.c,v 1.172 2022/02/01 23:32:51 djm Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * @@ -66,7 +66,7 @@ static int kex_choose_conf(struct ssh *); static int kex_input_newkeys(int, u_int32_t, struct ssh *); -static const char *proposal_names[PROPOSAL_MAX] = { +static const char * const proposal_names[PROPOSAL_MAX] = { "KEX algorithms", "host key algorithms", "ciphers ctos", @@ -436,9 +436,12 @@ kex_send_ext_info(struct ssh *ssh) return SSH_ERR_ALLOC_FAIL; /* XXX filter algs list by allowed pubkey/hostbased types */ if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 || - (r = sshpkt_put_u32(ssh, 1)) != 0 || + (r = sshpkt_put_u32(ssh, 2)) != 0 || (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 || (r = sshpkt_put_cstring(ssh, algs)) != 0 || + (r = sshpkt_put_cstring(ssh, + "publickey-hostbound@openssh.com")) != 0 || + (r = sshpkt_put_cstring(ssh, "0")) != 0 || (r = sshpkt_send(ssh)) != 0) { error_fr(r, "compose"); goto out; @@ -498,6 +501,21 @@ kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh) debug_f("%s=<%s>", name, val); kex->server_sig_algs = val; val = NULL; + } else if (strcmp(name, + "publickey-hostbound@openssh.com") == 0) { + /* XXX refactor */ + /* Ensure no \0 lurking in value */ + if (memchr(val, '\0', vlen) != NULL) { + error_f("nul byte in %s", name); + return SSH_ERR_INVALID_FORMAT; + } + debug_f("%s=<%s>", name, val); + if (strcmp(val, "0") == 0) + kex->flags |= KEX_HAS_PUBKEY_HOSTBOUND; + else { + debug_f("unsupported version of %s extension", + name); + } } else debug_f("%s (unrecognised)", name); free(name); @@ -699,6 +717,8 @@ kex_free(struct kex *kex) sshbuf_free(kex->server_version); sshbuf_free(kex->client_pub); sshbuf_free(kex->session_id); + sshbuf_free(kex->initial_sig); + sshkey_free(kex->initial_hostkey); free(kex->failed_choice); free(kex->hostkey_alg); free(kex->name); @@ -880,6 +900,18 @@ proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) return (1); } +/* returns non-zero if proposal contains any algorithm from algs */ +static int +has_any_alg(const char *proposal, const char *algs) +{ + char *cp; + + if ((cp = match_list(proposal, algs, NULL)) == NULL) + return 0; + free(cp); + return 1; +} + static int kex_choose_conf(struct ssh *ssh) { @@ -915,6 +947,16 @@ kex_choose_conf(struct ssh *ssh) free(ext); } + /* Check whether client supports rsa-sha2 algorithms */ + if (kex->server && (kex->flags & KEX_INITIAL)) { + if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS], + "rsa-sha2-256,rsa-sha2-256-cert-v01@openssh.com")) + kex->flags |= KEX_RSA_SHA2_256_SUPPORTED; + if (has_any_alg(peer[PROPOSAL_SERVER_HOST_KEY_ALGS], + "rsa-sha2-512,rsa-sha2-512-cert-v01@openssh.com")) + kex->flags |= KEX_RSA_SHA2_512_SUPPORTED; + } + /* Algorithm Negotiation */ if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS])) != 0) { |