diff options
Diffstat (limited to 'crypto/openssh/ssh_api.c')
| -rw-r--r-- | crypto/openssh/ssh_api.c | 537 |
1 files changed, 537 insertions, 0 deletions
diff --git a/crypto/openssh/ssh_api.c b/crypto/openssh/ssh_api.c new file mode 100644 index 0000000..6c71258 --- /dev/null +++ b/crypto/openssh/ssh_api.c @@ -0,0 +1,537 @@ +/* $OpenBSD: ssh_api.c,v 1.4 2015/02/16 22:13:32 djm Exp $ */ +/* + * Copyright (c) 2012 Markus Friedl. All rights reserved. + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include "includes.h" + +#include "ssh1.h" /* For SSH_MSG_NONE */ +#include "ssh_api.h" +#include "compat.h" +#include "log.h" +#include "authfile.h" +#include "sshkey.h" +#include "misc.h" +#include "ssh1.h" +#include "ssh2.h" +#include "version.h" +#include "myproposal.h" +#include "ssherr.h" +#include "sshbuf.h" + +#include <string.h> + +int _ssh_exchange_banner(struct ssh *); +int _ssh_send_banner(struct ssh *, char **); +int _ssh_read_banner(struct ssh *, char **); +int _ssh_order_hostkeyalgs(struct ssh *); +int _ssh_verify_host_key(struct sshkey *, struct ssh *); +struct sshkey *_ssh_host_public_key(int, int, struct ssh *); +struct sshkey *_ssh_host_private_key(int, int, struct ssh *); +int _ssh_host_key_sign(struct sshkey *, struct sshkey *, u_char **, + size_t *, const u_char *, size_t, u_int); + +/* + * stubs for the server side implementation of kex. + * disable privsep so our stubs will never be called. + */ +int use_privsep = 0; +int mm_sshkey_sign(struct sshkey *, u_char **, u_int *, + u_char *, u_int, u_int); +DH *mm_choose_dh(int, int, int); + +/* Define these two variables here so that they are part of the library */ +u_char *session_id2 = NULL; +u_int session_id2_len = 0; + +int +mm_sshkey_sign(struct sshkey *key, u_char **sigp, u_int *lenp, + u_char *data, u_int datalen, u_int compat) +{ + return (-1); +} + +DH * +mm_choose_dh(int min, int nbits, int max) +{ + return (NULL); +} + +/* API */ + +int +ssh_init(struct ssh **sshp, int is_server, struct kex_params *kex_params) +{ + char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT }; + struct ssh *ssh; + char **proposal; + static int called; + int r; + + if (!called) { +#ifdef WITH_OPENSSL + OpenSSL_add_all_algorithms(); +#endif /* WITH_OPENSSL */ + called = 1; + } + + if ((ssh = ssh_packet_set_connection(NULL, -1, -1)) == NULL) + return SSH_ERR_ALLOC_FAIL; + if (is_server) + ssh_packet_set_server(ssh); + + /* Initialize key exchange */ + proposal = kex_params ? kex_params->proposal : myproposal; + if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0) { + ssh_free(ssh); + return r; + } + ssh->kex->server = is_server; + if (is_server) { +#ifdef WITH_OPENSSL + ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; + ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; + ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; + ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; +# ifdef OPENSSL_HAS_ECC + ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_server; +# endif +#endif /* WITH_OPENSSL */ + ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_server; + ssh->kex->load_host_public_key=&_ssh_host_public_key; + ssh->kex->load_host_private_key=&_ssh_host_private_key; + ssh->kex->sign=&_ssh_host_key_sign; + } else { +#ifdef WITH_OPENSSL + ssh->kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client; + ssh->kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client; + ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; + ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; +# ifdef OPENSSL_HAS_ECC + ssh->kex->kex[KEX_ECDH_SHA2] = kexecdh_client; +# endif +#endif /* WITH_OPENSSL */ + ssh->kex->kex[KEX_C25519_SHA256] = kexc25519_client; + ssh->kex->verify_host_key =&_ssh_verify_host_key; + } + *sshp = ssh; + return 0; +} + +void +ssh_free(struct ssh *ssh) +{ + struct key_entry *k; + + ssh_packet_close(ssh); + /* + * we've only created the public keys variants in case we + * are a acting as a server. + */ + while ((k = TAILQ_FIRST(&ssh->public_keys)) != NULL) { + TAILQ_REMOVE(&ssh->public_keys, k, next); + if (ssh->kex && ssh->kex->server) + sshkey_free(k->key); + free(k); + } + while ((k = TAILQ_FIRST(&ssh->private_keys)) != NULL) { + TAILQ_REMOVE(&ssh->private_keys, k, next); + free(k); + } + if (ssh->kex) + kex_free(ssh->kex); + free(ssh); +} + +void +ssh_set_app_data(struct ssh *ssh, void *app_data) +{ + ssh->app_data = app_data; +} + +void * +ssh_get_app_data(struct ssh *ssh) +{ + return ssh->app_data; +} + +/* Returns < 0 on error, 0 otherwise */ +int +ssh_add_hostkey(struct ssh *ssh, struct sshkey *key) +{ + struct sshkey *pubkey = NULL; + struct key_entry *k = NULL, *k_prv = NULL; + int r; + + if (ssh->kex->server) { + if ((r = sshkey_from_private(key, &pubkey)) != 0) + return r; + if ((k = malloc(sizeof(*k))) == NULL || + (k_prv = malloc(sizeof(*k_prv))) == NULL) { + free(k); + sshkey_free(pubkey); + return SSH_ERR_ALLOC_FAIL; + } + k_prv->key = key; + TAILQ_INSERT_TAIL(&ssh->private_keys, k_prv, next); + + /* add the public key, too */ + k->key = pubkey; + TAILQ_INSERT_TAIL(&ssh->public_keys, k, next); + r = 0; + } else { + if ((k = malloc(sizeof(*k))) == NULL) + return SSH_ERR_ALLOC_FAIL; + k->key = key; + TAILQ_INSERT_TAIL(&ssh->public_keys, k, next); + r = 0; + } + + return r; +} + +int +ssh_set_verify_host_key_callback(struct ssh *ssh, + int (*cb)(struct sshkey *, struct ssh *)) +{ + if (cb == NULL || ssh->kex == NULL) + return SSH_ERR_INVALID_ARGUMENT; + + ssh->kex->verify_host_key = cb; + + return 0; +} + +int +ssh_input_append(struct ssh *ssh, const u_char *data, size_t len) +{ + return sshbuf_put(ssh_packet_get_input(ssh), data, len); +} + +int +ssh_packet_next(struct ssh *ssh, u_char *typep) +{ + int r; + u_int32_t seqnr; + u_char type; + + /* + * Try to read a packet. Return SSH_MSG_NONE if no packet or not + * enough data. + */ + *typep = SSH_MSG_NONE; + if (ssh->kex->client_version_string == NULL || + ssh->kex->server_version_string == NULL) + return _ssh_exchange_banner(ssh); + /* + * If we enough data and a dispatch function then + * call the function and get the next packet. + * Otherwise return the packet type to the caller so it + * can decide how to go on. + * + * We will only call the dispatch function for: + * 20-29 Algorithm negotiation + * 30-49 Key exchange method specific (numbers can be reused for + * different authentication methods) + */ + for (;;) { + if ((r = ssh_packet_read_poll2(ssh, &type, &seqnr)) != 0) + return r; + if (type > 0 && type < DISPATCH_MAX && + type >= SSH2_MSG_KEXINIT && type <= SSH2_MSG_TRANSPORT_MAX && + ssh->dispatch[type] != NULL) { + if ((r = (*ssh->dispatch[type])(type, seqnr, ssh)) != 0) + return r; + } else { + *typep = type; + return 0; + } + } +} + +const u_char * +ssh_packet_payload(struct ssh *ssh, size_t *lenp) +{ + return sshpkt_ptr(ssh, lenp); +} + +int +ssh_packet_put(struct ssh *ssh, int type, const u_char *data, size_t len) +{ + int r; + + if ((r = sshpkt_start(ssh, type)) != 0 || + (r = sshpkt_put(ssh, data, len)) != 0 || + (r = sshpkt_send(ssh)) != 0) + return r; + return 0; +} + +const u_char * +ssh_output_ptr(struct ssh *ssh, size_t *len) +{ + struct sshbuf *output = ssh_packet_get_output(ssh); + + *len = sshbuf_len(output); + return sshbuf_ptr(output); +} + +int +ssh_output_consume(struct ssh *ssh, size_t len) +{ + return sshbuf_consume(ssh_packet_get_output(ssh), len); +} + +int +ssh_output_space(struct ssh *ssh, size_t len) +{ + return (0 == sshbuf_check_reserve(ssh_packet_get_output(ssh), len)); +} + +int +ssh_input_space(struct ssh *ssh, size_t len) +{ + return (0 == sshbuf_check_reserve(ssh_packet_get_input(ssh), len)); +} + +/* Read other side's version identification. */ +int +_ssh_read_banner(struct ssh *ssh, char **bannerp) +{ + struct sshbuf *input; + const char *s; + char buf[256], remote_version[256]; /* must be same size! */ + const char *mismatch = "Protocol mismatch.\r\n"; + int r, remote_major, remote_minor; + size_t i, n, j, len; + + *bannerp = NULL; + input = ssh_packet_get_input(ssh); + len = sshbuf_len(input); + s = (const char *)sshbuf_ptr(input); + for (j = n = 0;;) { + for (i = 0; i < sizeof(buf) - 1; i++) { + if (j >= len) + return (0); + buf[i] = s[j++]; + if (buf[i] == '\r') { + buf[i] = '\n'; + buf[i + 1] = 0; + continue; /**XXX wait for \n */ + } + if (buf[i] == '\n') { + buf[i + 1] = 0; + break; + } + } + buf[sizeof(buf) - 1] = 0; + if (strncmp(buf, "SSH-", 4) == 0) + break; + debug("ssh_exchange_identification: %s", buf); + if (ssh->kex->server || ++n > 65536) { + if ((r = sshbuf_put(ssh_packet_get_output(ssh), + mismatch, strlen(mismatch))) != 0) + return r; + return SSH_ERR_NO_PROTOCOL_VERSION; + } + } + if ((r = sshbuf_consume(input, j)) != 0) + return r; + + /* + * Check that the versions match. In future this might accept + * several versions and set appropriate flags to handle them. + */ + if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", + &remote_major, &remote_minor, remote_version) != 3) + return SSH_ERR_INVALID_FORMAT; + debug("Remote protocol version %d.%d, remote software version %.100s", + remote_major, remote_minor, remote_version); + + ssh->compat = compat_datafellows(remote_version); + if (remote_major == 1 && remote_minor == 99) { + remote_major = 2; + remote_minor = 0; + } + if (remote_major != 2) + return SSH_ERR_PROTOCOL_MISMATCH; + enable_compat20(); + chop(buf); + debug("Remote version string %.100s", buf); + if ((*bannerp = strdup(buf)) == NULL) + return SSH_ERR_ALLOC_FAIL; + return 0; +} + +/* Send our own protocol version identification. */ +int +_ssh_send_banner(struct ssh *ssh, char **bannerp) +{ + char buf[256]; + int r; + + snprintf(buf, sizeof buf, "SSH-2.0-%.100s\r\n", SSH_VERSION); + if ((r = sshbuf_put(ssh_packet_get_output(ssh), buf, strlen(buf))) != 0) + return r; + chop(buf); + debug("Local version string %.100s", buf); + if ((*bannerp = strdup(buf)) == NULL) + return SSH_ERR_ALLOC_FAIL; + return 0; +} + +int +_ssh_exchange_banner(struct ssh *ssh) +{ + struct kex *kex = ssh->kex; + int r; + + /* + * if _ssh_read_banner() cannot parse a full version string + * it will return NULL and we end up calling it again. + */ + + r = 0; + if (kex->server) { + if (kex->server_version_string == NULL) + r = _ssh_send_banner(ssh, &kex->server_version_string); + if (r == 0 && + kex->server_version_string != NULL && + kex->client_version_string == NULL) + r = _ssh_read_banner(ssh, &kex->client_version_string); + } else { + if (kex->server_version_string == NULL) + r = _ssh_read_banner(ssh, &kex->server_version_string); + if (r == 0 && + kex->server_version_string != NULL && + kex->client_version_string == NULL) + r = _ssh_send_banner(ssh, &kex->client_version_string); + } + if (r != 0) + return r; + /* start initial kex as soon as we have exchanged the banners */ + if (kex->server_version_string != NULL && + kex->client_version_string != NULL) { + if ((r = _ssh_order_hostkeyalgs(ssh)) != 0 || + (r = kex_send_kexinit(ssh)) != 0) + return r; + } + return 0; +} + +struct sshkey * +_ssh_host_public_key(int type, int nid, struct ssh *ssh) +{ + struct key_entry *k; + + debug3("%s: need %d", __func__, type); + TAILQ_FOREACH(k, &ssh->public_keys, next) { + debug3("%s: check %s", __func__, sshkey_type(k->key)); + if (k->key->type == type && + (type != KEY_ECDSA || k->key->ecdsa_nid == nid)) + return (k->key); + } + return (NULL); +} + +struct sshkey * +_ssh_host_private_key(int type, int nid, struct ssh *ssh) +{ + struct key_entry *k; + + debug3("%s: need %d", __func__, type); + TAILQ_FOREACH(k, &ssh->private_keys, next) { + debug3("%s: check %s", __func__, sshkey_type(k->key)); + if (k->key->type == type && + (type != KEY_ECDSA || k->key->ecdsa_nid == nid)) + return (k->key); + } + return (NULL); +} + +int +_ssh_verify_host_key(struct sshkey *hostkey, struct ssh *ssh) +{ + struct key_entry *k; + + debug3("%s: need %s", __func__, sshkey_type(hostkey)); + TAILQ_FOREACH(k, &ssh->public_keys, next) { + debug3("%s: check %s", __func__, sshkey_type(k->key)); + if (sshkey_equal_public(hostkey, k->key)) + return (0); /* ok */ + } + return (-1); /* failed */ +} + +/* offer hostkey algorithms in kexinit depending on registered keys */ +int +_ssh_order_hostkeyalgs(struct ssh *ssh) +{ + struct key_entry *k; + char *orig, *avail, *oavail = NULL, *alg, *replace = NULL; + char **proposal; + size_t maxlen; + int ktype, r; + + /* XXX we de-serialize ssh->kex->my, modify it, and change it */ + if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0) + return r; + orig = proposal[PROPOSAL_SERVER_HOST_KEY_ALGS]; + if ((oavail = avail = strdup(orig)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + maxlen = strlen(avail) + 1; + if ((replace = calloc(1, maxlen)) == NULL) { + r = SSH_ERR_ALLOC_FAIL; + goto out; + } + *replace = '\0'; + while ((alg = strsep(&avail, ",")) && *alg != '\0') { + if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC) + continue; + TAILQ_FOREACH(k, &ssh->public_keys, next) { + if (k->key->type == ktype || + (sshkey_is_cert(k->key) && k->key->type == + sshkey_type_plain(ktype))) { + if (*replace != '\0') + strlcat(replace, ",", maxlen); + strlcat(replace, alg, maxlen); + break; + } + } + } + if (*replace != '\0') { + debug2("%s: orig/%d %s", __func__, ssh->kex->server, orig); + debug2("%s: replace/%d %s", __func__, ssh->kex->server, replace); + free(orig); + proposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = replace; + replace = NULL; /* owned by proposal */ + r = kex_prop2buf(ssh->kex->my, proposal); + } + out: + free(oavail); + free(replace); + kex_prop_free(proposal); + return r; +} + +int +_ssh_host_key_sign(struct sshkey *privkey, struct sshkey *pubkey, + u_char **signature, size_t *slen, + const u_char *data, size_t dlen, u_int compat) +{ + return sshkey_sign(privkey, signature, slen, data, dlen, compat); +} |
