/* $OpenBSD: ca.c,v 1.43 2023/03/26 18:11:48 tb Exp $ */ /* * Copyright (c) 2014 Reyk Floeter * Copyright (c) 2012 Gilles Chehade * * 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 #include #include #include #include #include #include #include "smtpd.h" #include "log.h" #include "ssl.h" static int ca_verify_cb(int, X509_STORE_CTX *); static int rsae_send_imsg(int, const unsigned char *, unsigned char *, RSA *, int, unsigned int); static int rsae_pub_enc(int, const unsigned char *, unsigned char *, RSA *, int); static int rsae_pub_dec(int,const unsigned char *, unsigned char *, RSA *, int); static int rsae_priv_enc(int, const unsigned char *, unsigned char *, RSA *, int); static int rsae_priv_dec(int, const unsigned char *, unsigned char *, RSA *, int); static int rsae_mod_exp(BIGNUM *, const BIGNUM *, RSA *, BN_CTX *); static int rsae_bn_mod_exp(BIGNUM *, const BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *, BN_MONT_CTX *); static int rsae_init(RSA *); static int rsae_finish(RSA *); static int rsae_keygen(RSA *, int, BIGNUM *, BN_GENCB *); static ECDSA_SIG *ecdsae_do_sign(const unsigned char *, int, const BIGNUM *, const BIGNUM *, EC_KEY *); static int ecdsae_sign_setup(EC_KEY *, BN_CTX *, BIGNUM **, BIGNUM **); static int ecdsae_do_verify(const unsigned char *, int, const ECDSA_SIG *, EC_KEY *); static struct dict pkeys; static uint64_t reqid = 0; static void ca_shutdown(void) { log_debug("debug: ca agent exiting"); _exit(0); } int ca(void) { struct passwd *pw; purge_config(PURGE_LISTENERS|PURGE_TABLES|PURGE_RULES|PURGE_DISPATCHERS); if ((pw = getpwnam(SMTPD_USER)) == NULL) fatalx("unknown user " SMTPD_USER); if (chroot(PATH_CHROOT) == -1) fatal("ca: chroot"); if (chdir("/") == -1) fatal("ca: chdir(\"/\")"); config_process(PROC_CA); if (setgroups(1, &pw->pw_gid) || setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) || setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid)) fatal("ca: cannot drop privileges"); imsg_callback = ca_imsg; event_init(); signal(SIGINT, SIG_IGN); signal(SIGTERM, SIG_IGN); signal(SIGPIPE, SIG_IGN); signal(SIGHUP, SIG_IGN); config_peer(PROC_CONTROL); config_peer(PROC_PARENT); config_peer(PROC_DISPATCHER); /* Ignore them until we get our config */ mproc_disable(p_dispatcher); if (pledge("stdio", NULL) == -1) fatal("pledge"); event_dispatch(); fatalx("exited event loop"); return (0); } void ca_init(void) { BIO *in = NULL; EVP_PKEY *pkey = NULL; struct pki *pki; const char *k; void *iter_dict; char *hash; log_debug("debug: init private ssl-tree"); dict_init(&pkeys); iter_dict = NULL; while (dict_iter(env->sc_pki_dict, &iter_dict, &k, (void **)&pki)) { if (pki->pki_key == NULL) continue; in = BIO_new_mem_buf(pki->pki_key, pki->pki_key_len); if (in == NULL) fatalx("ca_init: key"); pkey = PEM_read_bio_PrivateKey(in, NULL, NULL, NULL); if (pkey == NULL) fatalx("ca_init: PEM"); BIO_free(in); hash = ssl_pubkey_hash(pki->pki_cert, pki->pki_cert_len); if (dict_check(&pkeys, hash)) EVP_PKEY_free(pkey); else dict_xset(&pkeys, hash, pkey); free(hash); } } static int ca_verify_cb(int ok, X509_STORE_CTX *ctx) { switch (X509_STORE_CTX_get_error(ctx)) { case X509_V_OK: break; case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT: break; case X509_V_ERR_CERT_NOT_YET_VALID: case X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD: break; case X509_V_ERR_CERT_HAS_EXPIRED: case X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD: break; case X509_V_ERR_NO_EXPLICIT_POLICY: break; } return ok; } int ca_X509_verify(void *certificate, void *chain, const char *CAfile, const char *CRLfile, const char **errstr) { X509_STORE *store = NULL; X509_STORE_CTX *xsc = NULL; int ret = 0; long error = 0; if ((store = X509_STORE_new()) == NULL) goto end; if (!X509_STORE_load_locations(store, CAfile, NULL)) { log_warn("warn: unable to load CA file %s", CAfile); goto end; } X509_STORE_set_default_paths(store); if ((xsc = X509_STORE_CTX_new()) == NULL) goto end; if (X509_STORE_CTX_init(xsc, store, certificate, chain) != 1) goto end; X509_STORE_CTX_set_verify_cb(xsc, ca_verify_cb); ret = X509_verify_cert(xsc); end: *errstr = NULL; if (ret != 1) { if (xsc) { error = X509_STORE_CTX_get_error(xsc); *errstr = X509_verify_cert_error_string(error); } else if (ERR_peek_last_error()) *errstr = ERR_error_string(ERR_peek_last_error(), NULL); } X509_STORE_CTX_free(xsc); X509_STORE_free(store); return ret > 0 ? 1 : 0; } void ca_imsg(struct mproc *p, struct imsg *imsg) { EVP_PKEY *pkey; RSA *rsa = NULL; EC_KEY *ecdsa = NULL; const void *from = NULL; unsigned char *to = NULL; struct msg m; const char *hash; size_t flen, tlen, padding; int buf_len; int ret = 0; uint64_t id; int v; if (imsg == NULL) ca_shutdown(); switch (imsg->hdr.type) { case IMSG_CONF_START: return; case IMSG_CONF_END: ca_init(); /* Start fulfilling requests */ mproc_enable(p_dispatcher); return; case IMSG_CTL_VERBOSE: m_msg(&m, imsg); m_get_int(&m, &v); m_end(&m); log_trace_verbose(v); return; case IMSG_CTL_PROFILE: m_msg(&m, imsg); m_get_int(&m, &v); m_end(&m); profiling = v; return; case IMSG_CA_RSA_PRIVENC: case IMSG_CA_RSA_PRIVDEC: m_msg(&m, imsg); m_get_id(&m, &id); m_get_string(&m, &hash); m_get_data(&m, &from, &flen); m_get_size(&m, &tlen); m_get_size(&m, &padding); m_end(&m); pkey = dict_get(&pkeys, hash); if (pkey == NULL || (rsa = EVP_PKEY_get1_RSA(pkey)) == NULL) fatalx("ca_imsg: invalid pkey hash"); if ((to = calloc(1, tlen)) == NULL) fatalx("ca_imsg: calloc"); switch (imsg->hdr.type) { case IMSG_CA_RSA_PRIVENC: ret = RSA_private_encrypt(flen, from, to, rsa, padding); break; case IMSG_CA_RSA_PRIVDEC: ret = RSA_private_decrypt(flen, from, to, rsa, padding); break; } m_create(p, imsg->hdr.type, 0, 0, -1); m_add_id(p, id); m_add_int(p, ret); if (ret > 0) m_add_data(p, to, (size_t)ret); m_close(p); free(to); RSA_free(rsa); return; case IMSG_CA_ECDSA_SIGN: m_msg(&m, imsg); m_get_id(&m, &id); m_get_string(&m, &hash); m_get_data(&m, &from, &flen); m_end(&m); pkey = dict_get(&pkeys, hash); if (pkey == NULL || (ecdsa = EVP_PKEY_get1_EC_KEY(pkey)) == NULL) fatalx("ca_imsg: invalid pkey hash"); buf_len = ECDSA_size(ecdsa); if ((to = calloc(1, buf_len)) == NULL) fatalx("ca_imsg: calloc"); ret = ECDSA_sign(0, from, flen, to, &buf_len, ecdsa); m_create(p, imsg->hdr.type, 0, 0, -1); m_add_id(p, id); m_add_int(p, ret); if (ret > 0) m_add_data(p, to, (size_t)buf_len); m_close(p); free(to); EC_KEY_free(ecdsa); return; } fatalx("ca_imsg: unexpected %s imsg", imsg_to_str(imsg->hdr.type)); } /* * RSA privsep engine (called from unprivileged processes) */ const RSA_METHOD *rsa_default = NULL; static RSA_METHOD *rsae_method = NULL; static int rsae_send_imsg(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding, unsigned int cmd) { int ret = 0; struct imsgbuf *ibuf; struct imsg imsg; int n, done = 0; const void *toptr; char *hash; size_t tlen; struct msg m; uint64_t id; if ((hash = RSA_get_ex_data(rsa, 0)) == NULL) return (0); /* * Send a synchronous imsg because we cannot defer the RSA * operation in OpenSSL's engine layer. */ m_create(p_ca, cmd, 0, 0, -1); reqid++; m_add_id(p_ca, reqid); m_add_string(p_ca, hash); m_add_data(p_ca, (const void *)from, (size_t)flen); m_add_size(p_ca, (size_t)RSA_size(rsa)); m_add_size(p_ca, (size_t)padding); m_flush(p_ca); ibuf = &p_ca->imsgbuf; while (!done) { if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN) fatalx("imsg_read"); if (n == 0) fatalx("pipe closed"); while (!done) { if ((n = imsg_get(ibuf, &imsg)) == -1) fatalx("imsg_get error"); if (n == 0) break; log_imsg(PROC_DISPATCHER, PROC_CA, &imsg); switch (imsg.hdr.type) { case IMSG_CA_RSA_PRIVENC: case IMSG_CA_RSA_PRIVDEC: break; default: /* Another imsg is queued up in the buffer */ dispatcher_imsg(p_ca, &imsg); imsg_free(&imsg); continue; } m_msg(&m, &imsg); m_get_id(&m, &id); if (id != reqid) fatalx("invalid response id"); m_get_int(&m, &ret); if (ret > 0) m_get_data(&m, &toptr, &tlen); m_end(&m); if (ret > 0) memcpy(to, toptr, tlen); done = 1; imsg_free(&imsg); } } mproc_event_add(p_ca); return (ret); } static int rsae_pub_enc(int flen,const unsigned char *from, unsigned char *to, RSA *rsa, int padding) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (RSA_meth_get_pub_enc(rsa_default)(flen, from, to, rsa, padding)); } static int rsae_pub_dec(int flen,const unsigned char *from, unsigned char *to, RSA *rsa, int padding) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (RSA_meth_get_pub_dec(rsa_default)(flen, from, to, rsa, padding)); } static int rsae_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); if (RSA_get_ex_data(rsa, 0) != NULL) return (rsae_send_imsg(flen, from, to, rsa, padding, IMSG_CA_RSA_PRIVENC)); return (RSA_meth_get_priv_enc(rsa_default)(flen, from, to, rsa, padding)); } static int rsae_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); if (RSA_get_ex_data(rsa, 0) != NULL) return (rsae_send_imsg(flen, from, to, rsa, padding, IMSG_CA_RSA_PRIVDEC)); return (RSA_meth_get_priv_dec(rsa_default)(flen, from, to, rsa, padding)); } static int rsae_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (RSA_meth_get_mod_exp(rsa_default)(r0, I, rsa, ctx)); } static int rsae_bn_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (RSA_meth_get_bn_mod_exp(rsa_default)(r, a, p, m, ctx, m_ctx)); } static int rsae_init(RSA *rsa) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); if (RSA_meth_get_init(rsa_default) == NULL) return (1); return (RSA_meth_get_init(rsa_default)(rsa)); } static int rsae_finish(RSA *rsa) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); if (RSA_meth_get_finish(rsa_default) == NULL) return (1); return (RSA_meth_get_finish(rsa_default)(rsa)); } static int rsae_keygen(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (RSA_meth_get_keygen(rsa_default)(rsa, bits, e, cb)); } /* * ECDSA privsep engine (called from unprivileged processes) */ const ECDSA_METHOD *ecdsa_default = NULL; static ECDSA_METHOD *ecdsae_method = NULL; ECDSA_METHOD * ECDSA_METHOD_new_temporary(const char *name, int); ECDSA_METHOD * ECDSA_METHOD_new_temporary(const char *name, int flags) { ECDSA_METHOD *ecdsa; if ((ecdsa = calloc(1, sizeof (*ecdsa))) == NULL) return NULL; if ((ecdsa->name = strdup(name)) == NULL) { free(ecdsa); return NULL; } ecdsa->flags = flags; return ecdsa; } static ECDSA_SIG * ecdsae_send_enc_imsg(const unsigned char *dgst, int dgst_len, const BIGNUM *inv, const BIGNUM *rp, EC_KEY *eckey) { int ret = 0; struct imsgbuf *ibuf; struct imsg imsg; int n, done = 0; const void *toptr; char *hash; size_t tlen; struct msg m; uint64_t id; ECDSA_SIG *sig = NULL; if ((hash = ECDSA_get_ex_data(eckey, 0)) == NULL) return (0); /* * Send a synchronous imsg because we cannot defer the ECDSA * operation in OpenSSL's engine layer. */ m_create(p_ca, IMSG_CA_ECDSA_SIGN, 0, 0, -1); reqid++; m_add_id(p_ca, reqid); m_add_string(p_ca, hash); m_add_data(p_ca, (const void *)dgst, (size_t)dgst_len); m_flush(p_ca); ibuf = &p_ca->imsgbuf; while (!done) { if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN) fatalx("imsg_read"); if (n == 0) fatalx("pipe closed"); while (!done) { if ((n = imsg_get(ibuf, &imsg)) == -1) fatalx("imsg_get error"); if (n == 0) break; log_imsg(PROC_DISPATCHER, PROC_CA, &imsg); switch (imsg.hdr.type) { case IMSG_CA_ECDSA_SIGN: break; default: /* Another imsg is queued up in the buffer */ dispatcher_imsg(p_ca, &imsg); imsg_free(&imsg); continue; } m_msg(&m, &imsg); m_get_id(&m, &id); if (id != reqid) fatalx("invalid response id"); m_get_int(&m, &ret); if (ret > 0) m_get_data(&m, &toptr, &tlen); m_end(&m); done = 1; if (ret > 0) d2i_ECDSA_SIG(&sig, (const unsigned char **)&toptr, tlen); imsg_free(&imsg); } } mproc_event_add(p_ca); return (sig); } ECDSA_SIG * ecdsae_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv, const BIGNUM *rp, EC_KEY *eckey) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); if (ECDSA_get_ex_data(eckey, 0) != NULL) return (ecdsae_send_enc_imsg(dgst, dgst_len, inv, rp, eckey)); return (ecdsa_default->ecdsa_do_sign(dgst, dgst_len, inv, rp, eckey)); } int ecdsae_sign_setup(EC_KEY *eckey, BN_CTX *ctx, BIGNUM **kinv, BIGNUM **r) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (ecdsa_default->ecdsa_sign_setup(eckey, ctx, kinv, r)); } int ecdsae_do_verify(const unsigned char *dgst, int dgst_len, const ECDSA_SIG *sig, EC_KEY *eckey) { log_debug("debug: %s: %s", proc_name(smtpd_process), __func__); return (ecdsa_default->ecdsa_do_verify(dgst, dgst_len, sig, eckey)); } static void rsa_engine_init(void) { ENGINE *e; const char *errstr, *name; if ((rsae_method = RSA_meth_new("RSA privsep engine", 0)) == NULL) { errstr = "RSA_meth_new"; goto fail; } RSA_meth_set_pub_enc(rsae_method, rsae_pub_enc); RSA_meth_set_pub_dec(rsae_method, rsae_pub_dec); RSA_meth_set_priv_enc(rsae_method, rsae_priv_enc); RSA_meth_set_priv_dec(rsae_method, rsae_priv_dec); RSA_meth_set_mod_exp(rsae_method, rsae_mod_exp); RSA_meth_set_bn_mod_exp(rsae_method, rsae_bn_mod_exp); RSA_meth_set_init(rsae_method, rsae_init); RSA_meth_set_finish(rsae_method, rsae_finish); RSA_meth_set_keygen(rsae_method, rsae_keygen); if ((e = ENGINE_get_default_RSA()) == NULL) { if ((e = ENGINE_new()) == NULL) { errstr = "ENGINE_new"; goto fail; } if (!ENGINE_set_name(e, RSA_meth_get0_name(rsae_method))) { errstr = "ENGINE_set_name"; goto fail; } if ((rsa_default = RSA_get_default_method()) == NULL) { errstr = "RSA_get_default_method"; goto fail; } } else if ((rsa_default = ENGINE_get_RSA(e)) == NULL) { errstr = "ENGINE_get_RSA"; goto fail; } if ((name = ENGINE_get_name(e)) == NULL) name = "unknown RSA engine"; log_debug("debug: %s: using %s", __func__, name); if (RSA_meth_get_mod_exp(rsa_default) == NULL) RSA_meth_set_mod_exp(rsae_method, NULL); if (RSA_meth_get_bn_mod_exp(rsa_default) == NULL) RSA_meth_set_bn_mod_exp(rsae_method, NULL); if (RSA_meth_get_keygen(rsa_default) == NULL) RSA_meth_set_keygen(rsae_method, NULL); RSA_meth_set_flags(rsae_method, RSA_meth_get_flags(rsa_default) | RSA_METHOD_FLAG_NO_CHECK); RSA_meth_set0_app_data(rsae_method, RSA_meth_get0_app_data(rsa_default)); if (!ENGINE_set_RSA(e, rsae_method)) { errstr = "ENGINE_set_RSA"; goto fail; } if (!ENGINE_set_default_RSA(e)) { errstr = "ENGINE_set_default_RSA"; goto fail; } return; fail: ssl_error(errstr); fatalx("%s", errstr); } static void ecdsa_engine_init(void) { ENGINE *e; const char *errstr, *name; if ((ecdsae_method = ECDSA_METHOD_new_temporary("ECDSA privsep engine", 0)) == NULL) { errstr = "ECDSA_METHOD_new_temporary"; goto fail; } ecdsae_method->ecdsa_do_sign = ecdsae_do_sign; ecdsae_method->ecdsa_sign_setup = ecdsae_sign_setup; ecdsae_method->ecdsa_do_verify = ecdsae_do_verify; if ((e = ENGINE_get_default_ECDSA()) == NULL) { if ((e = ENGINE_new()) == NULL) { errstr = "ENGINE_new"; goto fail; } if (!ENGINE_set_name(e, ecdsae_method->name)) { errstr = "ENGINE_set_name"; goto fail; } if ((ecdsa_default = ECDSA_get_default_method()) == NULL) { errstr = "ECDSA_get_default_method"; goto fail; } } else if ((ecdsa_default = ENGINE_get_ECDSA(e)) == NULL) { errstr = "ENGINE_get_ECDSA"; goto fail; } if ((name = ENGINE_get_name(e)) == NULL) name = "unknown ECDSA engine"; log_debug("debug: %s: using %s", __func__, name); if (!ENGINE_set_ECDSA(e, ecdsae_method)) { errstr = "ENGINE_set_ECDSA"; goto fail; } if (!ENGINE_set_default_ECDSA(e)) { errstr = "ENGINE_set_default_ECDSA"; goto fail; } return; fail: ssl_error(errstr); fatalx("%s", errstr); } void ca_engine_init(void) { rsa_engine_init(); ecdsa_engine_init(); }