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Diffstat (limited to '')
| -rw-r--r-- | ssh-pkcs11-client.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c new file mode 100644 index 0000000..8a0ffef --- /dev/null +++ b/ssh-pkcs11-client.c @@ -0,0 +1,392 @@ +/* $OpenBSD: ssh-pkcs11-client.c,v 1.16 2020/01/25 00:03:36 djm Exp $ */ +/* + * Copyright (c) 2010 Markus Friedl. All rights reserved. + * Copyright (c) 2014 Pedro Martelletto. 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" + +#ifdef ENABLE_PKCS11 + +#include <sys/types.h> +#ifdef HAVE_SYS_TIME_H +# include <sys/time.h> +#endif +#include <sys/socket.h> + +#include <stdarg.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> + +#include <openssl/ecdsa.h> +#include <openssl/rsa.h> + +#include "openbsd-compat/openssl-compat.h" + +#include "pathnames.h" +#include "xmalloc.h" +#include "sshbuf.h" +#include "log.h" +#include "misc.h" +#include "sshkey.h" +#include "authfd.h" +#include "atomicio.h" +#include "ssh-pkcs11.h" +#include "ssherr.h" + +/* borrows code from sftp-server and ssh-agent */ + +static int fd = -1; +static pid_t pid = -1; + +static void +send_msg(struct sshbuf *m) +{ + u_char buf[4]; + size_t mlen = sshbuf_len(m); + int r; + + POKE_U32(buf, mlen); + if (atomicio(vwrite, fd, buf, 4) != 4 || + atomicio(vwrite, fd, sshbuf_mutable_ptr(m), + sshbuf_len(m)) != sshbuf_len(m)) + error("write to helper failed"); + if ((r = sshbuf_consume(m, mlen)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); +} + +static int +recv_msg(struct sshbuf *m) +{ + u_int l, len; + u_char c, buf[1024]; + int r; + + if ((len = atomicio(read, fd, buf, 4)) != 4) { + error("read from helper failed: %u", len); + return (0); /* XXX */ + } + len = PEEK_U32(buf); + if (len > 256 * 1024) + fatal("response too long: %u", len); + /* read len bytes into m */ + sshbuf_reset(m); + while (len > 0) { + l = len; + if (l > sizeof(buf)) + l = sizeof(buf); + if (atomicio(read, fd, buf, l) != l) { + error("response from helper failed."); + return (0); /* XXX */ + } + if ((r = sshbuf_put(m, buf, l)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + len -= l; + } + if ((r = sshbuf_get_u8(m, &c)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + return c; +} + +int +pkcs11_init(int interactive) +{ + return (0); +} + +void +pkcs11_terminate(void) +{ + if (fd >= 0) + close(fd); +} + +static int +rsa_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, int padding) +{ + struct sshkey *key = NULL; + struct sshbuf *msg = NULL; + u_char *blob = NULL, *signature = NULL; + size_t blen, slen = 0; + int r, ret = -1; + + if (padding != RSA_PKCS1_PADDING) + goto fail; + key = sshkey_new(KEY_UNSPEC); + if (key == NULL) { + error("%s: sshkey_new failed", __func__); + goto fail; + } + key->type = KEY_RSA; + RSA_up_ref(rsa); + key->rsa = rsa; + if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) { + error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); + goto fail; + } + if ((msg = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || + (r = sshbuf_put_string(msg, blob, blen)) != 0 || + (r = sshbuf_put_string(msg, from, flen)) != 0 || + (r = sshbuf_put_u32(msg, 0)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + send_msg(msg); + sshbuf_reset(msg); + + if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) { + if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + if (slen <= (size_t)RSA_size(rsa)) { + memcpy(to, signature, slen); + ret = slen; + } + free(signature); + } + fail: + free(blob); + sshkey_free(key); + sshbuf_free(msg); + return (ret); +} + +#ifdef HAVE_EC_KEY_METHOD_NEW +static ECDSA_SIG * +ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv, + const BIGNUM *rp, EC_KEY *ec) +{ + struct sshkey *key = NULL; + struct sshbuf *msg = NULL; + ECDSA_SIG *ret = NULL; + const u_char *cp; + u_char *blob = NULL, *signature = NULL; + size_t blen, slen = 0; + int r, nid; + + nid = sshkey_ecdsa_key_to_nid(ec); + if (nid < 0) { + error("%s: couldn't get curve nid", __func__); + goto fail; + } + + key = sshkey_new(KEY_UNSPEC); + if (key == NULL) { + error("%s: sshkey_new failed", __func__); + goto fail; + } + key->ecdsa = ec; + key->ecdsa_nid = nid; + key->type = KEY_ECDSA; + EC_KEY_up_ref(ec); + + if ((r = sshkey_to_blob(key, &blob, &blen)) != 0) { + error("%s: sshkey_to_blob: %s", __func__, ssh_err(r)); + goto fail; + } + if ((msg = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 || + (r = sshbuf_put_string(msg, blob, blen)) != 0 || + (r = sshbuf_put_string(msg, dgst, dgst_len)) != 0 || + (r = sshbuf_put_u32(msg, 0)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + send_msg(msg); + sshbuf_reset(msg); + + if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) { + if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + cp = signature; + ret = d2i_ECDSA_SIG(NULL, &cp, slen); + free(signature); + } + + fail: + free(blob); + sshkey_free(key); + sshbuf_free(msg); + return (ret); +} +#endif /* HAVE_EC_KEY_METHOD_NEW */ + +static RSA_METHOD *helper_rsa; +#ifdef HAVE_EC_KEY_METHOD_NEW +static EC_KEY_METHOD *helper_ecdsa; +#endif /* HAVE_EC_KEY_METHOD_NEW */ + +/* redirect private key crypto operations to the ssh-pkcs11-helper */ +static void +wrap_key(struct sshkey *k) +{ + if (k->type == KEY_RSA) + RSA_set_method(k->rsa, helper_rsa); +#ifdef HAVE_EC_KEY_METHOD_NEW + else if (k->type == KEY_ECDSA) + EC_KEY_set_method(k->ecdsa, helper_ecdsa); +#endif /* HAVE_EC_KEY_METHOD_NEW */ + else + fatal("%s: unknown key type", __func__); +} + +static int +pkcs11_start_helper_methods(void) +{ + if (helper_rsa != NULL) + return (0); + +#ifdef HAVE_EC_KEY_METHOD_NEW + int (*orig_sign)(int, const unsigned char *, int, unsigned char *, + unsigned int *, const BIGNUM *, const BIGNUM *, EC_KEY *) = NULL; + if (helper_ecdsa != NULL) + return (0); + helper_ecdsa = EC_KEY_METHOD_new(EC_KEY_OpenSSL()); + if (helper_ecdsa == NULL) + return (-1); + EC_KEY_METHOD_get_sign(helper_ecdsa, &orig_sign, NULL, NULL); + EC_KEY_METHOD_set_sign(helper_ecdsa, orig_sign, NULL, ecdsa_do_sign); +#endif /* HAVE_EC_KEY_METHOD_NEW */ + + if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL) + fatal("%s: RSA_meth_dup failed", __func__); + if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") || + !RSA_meth_set_priv_enc(helper_rsa, rsa_encrypt)) + fatal("%s: failed to prepare method", __func__); + + return (0); +} + +static int +pkcs11_start_helper(void) +{ + int pair[2]; + char *helper, *verbosity = NULL; + + if (log_level_get() >= SYSLOG_LEVEL_DEBUG1) + verbosity = "-vvv"; + + if (pkcs11_start_helper_methods() == -1) { + error("pkcs11_start_helper_methods failed"); + return (-1); + } + + if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) { + error("socketpair: %s", strerror(errno)); + return (-1); + } + if ((pid = fork()) == -1) { + error("fork: %s", strerror(errno)); + return (-1); + } else if (pid == 0) { + if ((dup2(pair[1], STDIN_FILENO) == -1) || + (dup2(pair[1], STDOUT_FILENO) == -1)) { + fprintf(stderr, "dup2: %s\n", strerror(errno)); + _exit(1); + } + close(pair[0]); + close(pair[1]); + helper = getenv("SSH_PKCS11_HELPER"); + if (helper == NULL || strlen(helper) == 0) + helper = _PATH_SSH_PKCS11_HELPER; + debug("%s: starting %s %s", __func__, helper, + verbosity == NULL ? "" : verbosity); + execlp(helper, helper, verbosity, (char *)NULL); + fprintf(stderr, "exec: %s: %s\n", helper, strerror(errno)); + _exit(1); + } + close(pair[1]); + fd = pair[0]; + return (0); +} + +int +pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp, + char ***labelsp) +{ + struct sshkey *k; + int r, type; + u_char *blob; + char *label; + size_t blen; + u_int nkeys, i; + struct sshbuf *msg; + + if (fd < 0 && pkcs11_start_helper() < 0) + return (-1); + + if ((msg = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + if ((r = sshbuf_put_u8(msg, SSH_AGENTC_ADD_SMARTCARD_KEY)) != 0 || + (r = sshbuf_put_cstring(msg, name)) != 0 || + (r = sshbuf_put_cstring(msg, pin)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + send_msg(msg); + sshbuf_reset(msg); + + type = recv_msg(msg); + if (type == SSH2_AGENT_IDENTITIES_ANSWER) { + if ((r = sshbuf_get_u32(msg, &nkeys)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + *keysp = xcalloc(nkeys, sizeof(struct sshkey *)); + if (labelsp) + *labelsp = xcalloc(nkeys, sizeof(char *)); + for (i = 0; i < nkeys; i++) { + /* XXX clean up properly instead of fatal() */ + if ((r = sshbuf_get_string(msg, &blob, &blen)) != 0 || + (r = sshbuf_get_cstring(msg, &label, NULL)) != 0) + fatal("%s: buffer error: %s", + __func__, ssh_err(r)); + if ((r = sshkey_from_blob(blob, blen, &k)) != 0) + fatal("%s: bad key: %s", __func__, ssh_err(r)); + wrap_key(k); + (*keysp)[i] = k; + if (labelsp) + (*labelsp)[i] = label; + else + free(label); + free(blob); + } + } else if (type == SSH2_AGENT_FAILURE) { + if ((r = sshbuf_get_u32(msg, &nkeys)) != 0) + nkeys = -1; + } else { + nkeys = -1; + } + sshbuf_free(msg); + return (nkeys); +} + +int +pkcs11_del_provider(char *name) +{ + int r, ret = -1; + struct sshbuf *msg; + + if ((msg = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 || + (r = sshbuf_put_cstring(msg, name)) != 0 || + (r = sshbuf_put_cstring(msg, "")) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + send_msg(msg); + sshbuf_reset(msg); + + if (recv_msg(msg) == SSH_AGENT_SUCCESS) + ret = 0; + sshbuf_free(msg); + return (ret); +} + +#endif /* ENABLE_PKCS11 */ |