diff options
Diffstat (limited to 'kex.c')
| -rw-r--r-- | kex.c | 93 |
1 files changed, 86 insertions, 7 deletions
@@ -1,4 +1,4 @@ -/* $OpenBSD: kex.c,v 1.106 2015/04/17 13:25:52 djm Exp $ */ +/* $OpenBSD: kex.c,v 1.109 2015/07/30 00:01:34 djm Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * @@ -155,6 +155,68 @@ kex_names_valid(const char *names) return 1; } +/* + * Concatenate algorithm names, avoiding duplicates in the process. + * Caller must free returned string. + */ +char * +kex_names_cat(const char *a, const char *b) +{ + char *ret = NULL, *tmp = NULL, *cp, *p; + size_t len; + + if (a == NULL || *a == '\0') + return NULL; + if (b == NULL || *b == '\0') + return strdup(a); + if (strlen(b) > 1024*1024) + return NULL; + len = strlen(a) + strlen(b) + 2; + if ((tmp = cp = strdup(b)) == NULL || + (ret = calloc(1, len)) == NULL) { + free(tmp); + return NULL; + } + strlcpy(ret, a, len); + for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) { + if (match_list(ret, p, NULL) != NULL) + continue; /* Algorithm already present */ + if (strlcat(ret, ",", len) >= len || + strlcat(ret, p, len) >= len) { + free(tmp); + free(ret); + return NULL; /* Shouldn't happen */ + } + } + free(tmp); + return ret; +} + +/* + * Assemble a list of algorithms from a default list and a string from a + * configuration file. The user-provided string may begin with '+' to + * indicate that it should be appended to the default. + */ +int +kex_assemble_names(const char *def, char **list) +{ + char *ret; + + if (list == NULL || *list == NULL || **list == '\0') { + *list = strdup(def); + return 0; + } + if (**list != '+') { + return 0; + } + + if ((ret = kex_names_cat(def, *list + 1)) == NULL) + return SSH_ERR_ALLOC_FAIL; + free(*list); + *list = ret; + return 0; +} + /* put algorithm proposal into buffer */ int kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX]) @@ -448,6 +510,7 @@ kex_free(struct kex *kex) free(kex->session_id); free(kex->client_version_string); free(kex->server_version_string); + free(kex->failed_choice); free(kex); } @@ -626,17 +689,26 @@ kex_choose_conf(struct ssh *ssh) nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; if ((r = choose_enc(&newkeys->enc, cprop[nenc], - sprop[nenc])) != 0) + sprop[nenc])) != 0) { + kex->failed_choice = peer[nenc]; + peer[nenc] = NULL; goto out; + } authlen = cipher_authlen(newkeys->enc.cipher); /* ignore mac for authenticated encryption */ if (authlen == 0 && (r = choose_mac(ssh, &newkeys->mac, cprop[nmac], - sprop[nmac])) != 0) + sprop[nmac])) != 0) { + kex->failed_choice = peer[nmac]; + peer[nmac] = NULL; goto out; + } if ((r = choose_comp(&newkeys->comp, cprop[ncomp], - sprop[ncomp])) != 0) + sprop[ncomp])) != 0) { + kex->failed_choice = peer[ncomp]; + peer[ncomp] = NULL; goto out; + } debug("kex: %s %s %s %s", ctos ? "client->server" : "server->client", newkeys->enc.name, @@ -644,10 +716,17 @@ kex_choose_conf(struct ssh *ssh) newkeys->comp.name); } if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], - sprop[PROPOSAL_KEX_ALGS])) != 0 || - (r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], - sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) + sprop[PROPOSAL_KEX_ALGS])) != 0) { + kex->failed_choice = peer[PROPOSAL_KEX_ALGS]; + peer[PROPOSAL_KEX_ALGS] = NULL; goto out; + } + if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], + sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) { + kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS]; + peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL; + goto out; + } need = dh_need = 0; for (mode = 0; mode < MODE_MAX; mode++) { newkeys = kex->newkeys[mode]; |