X-Git-Url: https://vcs.fsf.org/?p=exim.git;a=blobdiff_plain;f=src%2Fsrc%2Ftls-gnu.c;h=8b28d55664d779d1e6e01db346779511866298f5;hp=f0e391f9713ef53c7edd7940138a411e3a4ea16c;hb=0f0c8159c43045f4ad847a0129dca7eddd313285;hpb=17c761988f30054827a9951761d93ffeeaad0cb7 diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c index f0e391f97..8b28d5566 100644 --- a/src/src/tls-gnu.c +++ b/src/src/tls-gnu.c @@ -2,7 +2,7 @@ * Exim - an Internet mail transport agent * *************************************************/ -/* Copyright (c) University of Cambridge 1995 - 2012 */ +/* Copyright (c) University of Cambridge 1995 - 2014 */ /* See the file NOTICE for conditions of use and distribution. */ /* Copyright (c) Phil Pennock 2012 */ @@ -39,6 +39,30 @@ require current GnuTLS, then we'll drop support for the ancient libraries). #include /* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */ #include +/* needed to disable PKCS11 autoload unless requested */ +#if GNUTLS_VERSION_NUMBER >= 0x020c00 +# include +#endif +#if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP) +# warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile" +# define DISABLE_OCSP +#endif +#if GNUTLS_VERSION_NUMBER < 0x020a00 && defined(EXPERIMENTAL_EVENT) +# warning "GnuTLS library version too old; tls:cert event unsupported" +# undef EXPERIMENTAL_EVENT +#endif +#if GNUTLS_VERSION_NUMBER >= 0x030306 +# define SUPPORT_CA_DIR +#else +# undef SUPPORT_CA_DIR +#endif +#if GNUTLS_VERSION_NUMBER >= 0x030314 +# define SUPPORT_SYSDEFAULT_CABUNDLE +#endif + +#ifndef DISABLE_OCSP +# include +#endif /* GnuTLS 2 vs 3 @@ -53,7 +77,8 @@ Changes: /* Values for verify_requirement */ -enum peer_verify_requirement { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; +enum peer_verify_requirement + { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED }; /* This holds most state for server or client; with this, we can set up an outbound TLS-enabled connection in an ACL callout, while not stomping all @@ -63,22 +88,24 @@ Some of these correspond to variables in globals.c; those variables will be set to point to content in one of these instances, as appropriate for the stage of the process lifetime. -Not handled here: globals tls_active, tls_bits, tls_cipher, tls_peerdn, -tls_certificate_verified, tls_channelbinding_b64, tls_sni. +Not handled here: global tls_channelbinding_b64. */ typedef struct exim_gnutls_state { - gnutls_session_t session; + gnutls_session_t session; gnutls_certificate_credentials_t x509_cred; - gnutls_priority_t priority_cache; + gnutls_priority_t priority_cache; enum peer_verify_requirement verify_requirement; - int fd_in; - int fd_out; - BOOL peer_cert_verified; - BOOL trigger_sni_changes; + int fd_in; + int fd_out; + BOOL peer_cert_verified; + BOOL trigger_sni_changes; + BOOL have_set_peerdn; const struct host_item *host; - uschar *peerdn; - uschar *received_sni; + gnutls_x509_crt_t peercert; + uschar *peerdn; + uschar *ciphersuite; + uschar *received_sni; const uschar *tls_certificate; const uschar *tls_privatekey; @@ -86,29 +113,38 @@ typedef struct exim_gnutls_state { const uschar *tls_verify_certificates; const uschar *tls_crl; const uschar *tls_require_ciphers; + uschar *exp_tls_certificate; uschar *exp_tls_privatekey; - uschar *exp_tls_sni; uschar *exp_tls_verify_certificates; uschar *exp_tls_crl; uschar *exp_tls_require_ciphers; + uschar *exp_tls_ocsp_file; + uschar *exp_tls_verify_cert_hostnames; +#ifdef EXPERIMENTAL_EVENT + uschar *event_action; +#endif + + tls_support *tlsp; /* set in tls_init() */ uschar *xfer_buffer; int xfer_buffer_lwm; int xfer_buffer_hwm; int xfer_eof; int xfer_error; - - uschar cipherbuf[256]; } exim_gnutls_state_st; static const exim_gnutls_state_st exim_gnutls_state_init = { - NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, - NULL, NULL, NULL, - NULL, NULL, NULL, NULL, NULL, NULL, + NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE, + NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, + NULL, NULL, NULL, NULL, NULL, NULL, NULL, + NULL, +#ifdef EXPERIMENTAL_EVENT + NULL, +#endif + NULL, NULL, 0, 0, 0, 0, - "" }; /* Not only do we have our own APIs which don't pass around state, assuming @@ -118,10 +154,11 @@ context we're currently dealing with" pointer and rely upon being single-threaded to keep from processing data on an inbound TLS connection while talking to another TLS connection for an outbound check. This does mean that there's no way for heart-beats to be responded to, for the duration of the -second connection. */ +second connection. +XXX But see gnutls_session_get_ptr() +*/ static exim_gnutls_state_st state_server, state_client; -static exim_gnutls_state_st *current_global_tls_state; /* dh_params are initialised once within the lifetime of a process using TLS; if we used TLS in a long-lived daemon, we'd have to reconsider this. But we @@ -140,12 +177,6 @@ static const char * const exim_default_gnutls_priority = "NORMAL"; static BOOL exim_gnutls_base_init_done = FALSE; -/* ------------------------------------------------------------------------ */ -/* Callback declarations */ - -static void exim_gnutls_logger_cb(int level, const char *message); -static int exim_sni_handling_cb(gnutls_session_t session); - /* ------------------------------------------------------------------------ */ /* macros */ @@ -154,24 +185,60 @@ static int exim_sni_handling_cb(gnutls_session_t session); /* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup the library logging; a value less than 0 disables the calls to set up logging callbacks. */ -#define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 +#ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL +# define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1 +#endif + +#ifndef EXIM_CLIENT_DH_MIN_BITS +# define EXIM_CLIENT_DH_MIN_BITS 1024 +#endif -#define EXIM_CLIENT_DH_MIN_BITS 1024 +/* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we +can ask for a bit-strength. Without that, we stick to the constant we had +before, for now. */ +#ifndef EXIM_SERVER_DH_BITS_PRE2_12 +# define EXIM_SERVER_DH_BITS_PRE2_12 1024 +#endif #define exim_gnutls_err_check(Label) do { \ if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0) -#define exim_gnutls_err_debugreturn0(Label) do { \ - if (rc != GNUTLS_E_SUCCESS) { \ - DEBUG(D_tls) debug_printf("TLS failure: %s: %s", (Label), gnutls_strerror(rc)); \ - return 0; } } while (0) - #define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname) #if GNUTLS_VERSION_NUMBER >= 0x020c00 -#define HAVE_GNUTLS_SESSION_CHANNEL_BINDING +# define HAVE_GNUTLS_SESSION_CHANNEL_BINDING +# define HAVE_GNUTLS_SEC_PARAM_CONSTANTS +# define HAVE_GNUTLS_RND +/* The security fix we provide with the gnutls_allow_auto_pkcs11 option + * (4.82 PP/09) introduces a compatibility regression. The symbol simply + * isn't available sometimes, so this needs to become a conditional + * compilation; the sanest way to deal with this being a problem on + * older OSes is to block it in the Local/Makefile with this compiler + * definition */ +# ifndef AVOID_GNUTLS_PKCS11 +# define HAVE_GNUTLS_PKCS11 +# endif /* AVOID_GNUTLS_PKCS11 */ #endif + + + +/* ------------------------------------------------------------------------ */ +/* Callback declarations */ + +#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 +static void exim_gnutls_logger_cb(int level, const char *message); +#endif + +static int exim_sni_handling_cb(gnutls_session_t session); + +#ifndef DISABLE_OCSP +static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr, + gnutls_datum_t * ocsp_response); +#endif + + + /* ------------------------------------------------------------------------ */ /* Static functions */ @@ -201,7 +268,7 @@ tls_error(const uschar *prefix, const char *msg, const host_item *host) { if (host) { - log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s", + log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s)%s%s", host->name, host->address, prefix, msg ? ": " : "", msg ? msg : ""); return FAIL; } @@ -210,6 +277,7 @@ else uschar *conn_info = smtp_get_connection_info(); if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5; + /* I'd like to get separated H= here, but too hard for now */ log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s", conn_info, prefix, msg ? ": " : "", msg ? msg : ""); return DEFER; @@ -255,12 +323,40 @@ tls_error(when, msg, state->host); * Set various Exim expansion vars * *************************************************/ +#define exim_gnutls_cert_err(Label) \ + do \ + { \ + if (rc != GNUTLS_E_SUCCESS) \ + { \ + DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \ + (Label), gnutls_strerror(rc)); \ + return rc; \ + } \ + } while (0) + +static int +import_cert(const gnutls_datum * cert, gnutls_x509_crt_t * crtp) +{ +int rc; + +rc = gnutls_x509_crt_init(crtp); +exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)"); + +rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER); +exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]"); + +return rc; +} + +#undef exim_gnutls_cert_err + + /* We set various Exim global variables from the state, once a session has been established. With TLS callouts, may need to change this to stack variables, or just re-call it with the server state after client callout has finished. -Make sure anything set here is inset in tls_getc(). +Make sure anything set here is unset in tls_getc(). Sets: tls_active fd @@ -268,61 +364,37 @@ Sets: tls_certificate_verified bool indicator tls_channelbinding_b64 for some SASL mechanisms tls_cipher a string + tls_peercert pointer to library internal tls_peerdn a string tls_sni a (UTF-8) string -Also: - current_global_tls_state for API limitations + tls_ourcert pointer to library internal Argument: state the relevant exim_gnutls_state_st * */ static void -extract_exim_vars_from_tls_state(exim_gnutls_state_st *state) +extract_exim_vars_from_tls_state(exim_gnutls_state_st * state) { -gnutls_protocol_t protocol; gnutls_cipher_algorithm_t cipher; -gnutls_kx_algorithm_t kx; -gnutls_mac_algorithm_t mac; -uschar *p; #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING int old_pool; int rc; gnutls_datum_t channel; #endif +tls_support * tlsp = state->tlsp; -current_global_tls_state = state; - -tls_active = state->fd_out; +tlsp->active = state->fd_out; cipher = gnutls_cipher_get(state->session); /* returns size in "bytes" */ -tls_bits = gnutls_cipher_get_key_size(cipher) * 8; - -if (!*state->cipherbuf) - { - protocol = gnutls_protocol_get_version(state->session); - mac = gnutls_mac_get(state->session); - kx = gnutls_kx_get(state->session); - - string_format(state->cipherbuf, sizeof(state->cipherbuf), - "%s:%s:%u", - gnutls_protocol_get_name(protocol), - gnutls_cipher_suite_get_name(kx, cipher, mac), - tls_bits); +tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8; - /* I don't see a way that spaces could occur, in the current GnuTLS - code base, but it was a concern in the old code and perhaps older GnuTLS - releases did return "TLS 1.0"; play it safe, just in case. */ - for (p = state->cipherbuf; *p != '\0'; ++p) - if (isspace(*p)) - *p = '-'; - } -tls_cipher = state->cipherbuf; +tlsp->cipher = state->ciphersuite; -DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher); +DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite); -tls_certificate_verified = state->peer_cert_verified; +tlsp->certificate_verified = state->peer_cert_verified; /* note that tls_channelbinding_b64 is not saved to the spool file, since it's only available for use for authenticators while this TLS session is running. */ @@ -343,9 +415,17 @@ if (rc) { } #endif -tls_peerdn = state->peerdn; +/* peercert is set in peer_status() */ +tlsp->peerdn = state->peerdn; +tlsp->sni = state->received_sni; -tls_sni = state->received_sni; +/* record our certificate */ + { + const gnutls_datum * cert = gnutls_certificate_get_ours(state->session); + gnutls_x509_crt_t crt; + + tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL; + } } @@ -365,9 +445,6 @@ file is never present. If two processes both compute some new parameters, you waste a bit of effort, but it doesn't seem worth messing around with locking to prevent this. -Argument: - host NULL for server, server for client (for error handling) - Returns: OK/DEFER/FAIL */ @@ -377,25 +454,91 @@ init_server_dh(void) int fd, rc; unsigned int dh_bits; gnutls_datum m; -uschar filename[PATH_MAX]; +uschar filename_buf[PATH_MAX]; +uschar *filename = NULL; size_t sz; +uschar *exp_tls_dhparam; +BOOL use_file_in_spool = FALSE; +BOOL use_fixed_file = FALSE; host_item *host = NULL; /* dummy for macros */ -const char * const dh_param_fn_ext = "normal"; /* change as dh_bits changes */ DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n"); rc = gnutls_dh_params_init(&dh_server_params); exim_gnutls_err_check(US"gnutls_dh_params_init"); -/* If you change this, also change dh_param_fn_ext so that we can use a +m.data = NULL; +m.size = 0; + +if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam)) + return DEFER; + +if (!exp_tls_dhparam) + { + DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n"); + m.data = US std_dh_prime_default(); + m.size = Ustrlen(m.data); + } +else if (Ustrcmp(exp_tls_dhparam, "historic") == 0) + use_file_in_spool = TRUE; +else if (Ustrcmp(exp_tls_dhparam, "none") == 0) + { + DEBUG(D_tls) debug_printf("Requested no DH parameters.\n"); + return OK; + } +else if (exp_tls_dhparam[0] != '/') + { + m.data = US std_dh_prime_named(exp_tls_dhparam); + if (m.data == NULL) + return tls_error(US"No standard prime named", CS exp_tls_dhparam, NULL); + m.size = Ustrlen(m.data); + } +else + { + use_fixed_file = TRUE; + filename = exp_tls_dhparam; + } + +if (m.data) + { + rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM); + exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3"); + DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n"); + return OK; + } + +#ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS +/* If you change this constant, also change dh_param_fn_ext so that we can use a different filename and ensure we have sufficient bits. */ dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL); if (!dh_bits) return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL); +DEBUG(D_tls) + debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits.\n", + dh_bits); +#else +dh_bits = EXIM_SERVER_DH_BITS_PRE2_12; +DEBUG(D_tls) + debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits.\n", + dh_bits); +#endif -if (!string_format(filename, sizeof(filename), - "%s/gnutls-params-%s", spool_directory, dh_param_fn_ext)) - return tls_error(US"overlong filename", NULL, NULL); +/* Some clients have hard-coded limits. */ +if (dh_bits > tls_dh_max_bits) + { + DEBUG(D_tls) + debug_printf("tls_dh_max_bits clamping override, using %d bits instead.\n", + tls_dh_max_bits); + dh_bits = tls_dh_max_bits; + } + +if (use_file_in_spool) + { + if (!string_format(filename_buf, sizeof(filename_buf), + "%s/gnutls-params-%d", spool_directory, dh_bits)) + return tls_error(US"overlong filename", NULL, NULL); + filename = filename_buf; + } /* Open the cache file for reading and if successful, read it and set up the parameters. */ @@ -472,6 +615,7 @@ case. */ if (rc < 0) { uschar *temp_fn; + unsigned int dh_bits_gen = dh_bits; if ((PATH_MAX - Ustrlen(filename)) < 10) return tls_error(US"Filename too long to generate replacement", @@ -483,8 +627,26 @@ if (rc < 0) return tls_error(US"Unable to open temp file", strerror(errno), NULL); (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */ - DEBUG(D_tls) debug_printf("generating %d bits Diffie-Hellman key ...\n", dh_bits); - rc = gnutls_dh_params_generate2(dh_server_params, dh_bits); + /* GnuTLS overshoots! + * If we ask for 2236, we might get 2237 or more. + * But there's no way to ask GnuTLS how many bits there really are. + * We can ask how many bits were used in a TLS session, but that's it! + * The prime itself is hidden behind too much abstraction. + * So we ask for less, and proceed on a wing and a prayer. + * First attempt, subtracted 3 for 2233 and got 2240. + */ + if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10) + { + dh_bits_gen = dh_bits - 10; + DEBUG(D_tls) + debug_printf("being paranoid about DH generation, make it '%d' bits'\n", + dh_bits_gen); + } + + DEBUG(D_tls) + debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n", + dh_bits_gen); + rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen); exim_gnutls_err_check(US"gnutls_dh_params_generate2"); /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time, @@ -501,6 +663,7 @@ if (rc < 0) m.data = malloc(m.size); if (m.data == NULL) return tls_error(US"memory allocation failed", strerror(errno), NULL); + /* this will return a size 1 less than the allocation size above */ rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM, m.data, &sz); if (rc != GNUTLS_E_SUCCESS) @@ -508,6 +671,7 @@ if (rc < 0) free(m.data); exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real"); } + m.size = sz; /* shrink by 1, probably */ sz = write_to_fd_buf(fd, m.data, (size_t) m.size); if (sz != m.size) @@ -562,6 +726,7 @@ Returns: OK/DEFER/FAIL static int tls_expand_session_files(exim_gnutls_state_st *state) { +struct stat statbuf; int rc; const host_item *host = state->host; /* macro should be reconsidered? */ uschar *saved_tls_certificate = NULL; @@ -571,11 +736,15 @@ uschar *saved_tls_crl = NULL; int cert_count; /* We check for tls_sni *before* expansion. */ -if (!state->host) +if (!host) /* server */ { if (!state->received_sni) { - if (Ustrstr(state->tls_certificate, US"tls_sni")) + if (state->tls_certificate && + (Ustrstr(state->tls_certificate, US"tls_sni") || + Ustrstr(state->tls_certificate, US"tls_in_sni") || + Ustrstr(state->tls_certificate, US"tls_out_sni") + )) { DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n"); state->trigger_sni_changes = TRUE; @@ -583,6 +752,7 @@ if (!state->host) } else { + /* useful for debugging */ saved_tls_certificate = state->exp_tls_certificate; saved_tls_privatekey = state->exp_tls_privatekey; saved_tls_verify_certificates = state->exp_tls_verify_certificates; @@ -590,6 +760,9 @@ if (!state->host) } } +rc = gnutls_certificate_allocate_credentials(&state->x509_cred); +exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); + /* remember: expand_check_tlsvar() is expand_check() but fiddling with state members, assuming consistent naming; and expand_check() returns false if expansion failed, unless expansion was forced to fail. */ @@ -605,7 +778,7 @@ if (!expand_check_tlsvar(tls_certificate)) if ((state->exp_tls_certificate == NULL) || (*state->exp_tls_certificate == '\0')) { - if (state->host == NULL) + if (!host) return tls_error(US"no TLS server certificate is specified", NULL, NULL); else DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n"); @@ -625,7 +798,6 @@ if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0') if (state->exp_tls_certificate && *state->exp_tls_certificate) { - BOOL setit = TRUE; DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n", state->exp_tls_certificate, state->exp_tls_privatekey); @@ -634,25 +806,46 @@ if (state->exp_tls_certificate && *state->exp_tls_certificate) if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) && (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0)) { - DEBUG(D_tls) debug_printf("cert and key unchanged with SNI.\n"); - setit = FALSE; + DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n"); } else { - DEBUG(D_tls) debug_printf("SNI changed cert/key pair.\n"); + DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n"); } } - if (setit) - { - rc = gnutls_certificate_set_x509_key_file(state->x509_cred, - CS state->exp_tls_certificate, CS state->exp_tls_privatekey, - GNUTLS_X509_FMT_PEM); - exim_gnutls_err_check( - string_sprintf("cert/key setup: cert=%s key=%s", - state->exp_tls_certificate, state->exp_tls_privatekey)); - } + rc = gnutls_certificate_set_x509_key_file(state->x509_cred, + CS state->exp_tls_certificate, CS state->exp_tls_privatekey, + GNUTLS_X509_FMT_PEM); + exim_gnutls_err_check( + string_sprintf("cert/key setup: cert=%s key=%s", + state->exp_tls_certificate, state->exp_tls_privatekey)); + DEBUG(D_tls) debug_printf("TLS: cert/key registered\n"); + } /* tls_certificate */ + + +/* Set the OCSP stapling server info */ + +#ifndef DISABLE_OCSP +if ( !host /* server */ + && tls_ocsp_file + ) + { + if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", + &state->exp_tls_ocsp_file)) + return DEFER; + + /* Use the full callback method for stapling just to get observability. + More efficient would be to read the file once only, if it never changed + (due to SNI). Would need restart on file update, or watch datestamp. */ + + gnutls_certificate_set_ocsp_status_request_function(state->x509_cred, + server_ocsp_stapling_cb, state->exp_tls_ocsp_file); + + DEBUG(D_tls) debug_printf("Set OCSP response file %s\n", &state->exp_tls_ocsp_file); } +#endif + /* Set the trusted CAs file if one is provided, and then add the CRL if one is provided. Experiment shows that, if the certificate file is empty, an unhelpful @@ -662,89 +855,158 @@ behaviour. */ if (state->tls_verify_certificates && *state->tls_verify_certificates) { - struct stat statbuf; - BOOL setit_vc = TRUE, setit_crl = TRUE; - if (!expand_check_tlsvar(tls_verify_certificates)) return DEFER; +#ifndef SUPPORT_SYSDEFAULT_CABUNDLE + if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) + state->exp_tls_verify_certificates = NULL; +#endif if (state->tls_crl && *state->tls_crl) if (!expand_check_tlsvar(tls_crl)) return DEFER; - if (state->received_sni) + if (!(state->exp_tls_verify_certificates && + *state->exp_tls_verify_certificates)) { - if (Ustrcmp(state->exp_tls_verify_certificates, saved_tls_verify_certificates) == 0) - setit_vc = FALSE; - if (Ustrcmp(state->exp_tls_crl, saved_tls_crl) == 0) - setit_crl = FALSE; - } - - /* nb: early exit; change if add more expansions to this function */ - if (!(setit_vc || setit_crl)) + DEBUG(D_tls) + debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n"); + /* With no tls_verify_certificates, we ignore tls_crl too */ return OK; + } + } +else + { + DEBUG(D_tls) + debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n"); + return OK; + } +#ifdef SUPPORT_SYSDEFAULT_CABUNDLE +if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0) + cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred); +else +#endif + { if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0) { log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s " - "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, - strerror(errno)); + "(tls_verify_certificates): %s", state->exp_tls_verify_certificates, + strerror(errno)); return DEFER; } - if (!S_ISREG(statbuf.st_mode)) +#ifndef SUPPORT_CA_DIR + /* The test suite passes in /dev/null; we could check for that path explicitly, + but who knows if someone has some weird FIFO which always dumps some certs, or + other weirdness. The thing we really want to check is that it's not a + directory, since while OpenSSL supports that, GnuTLS does not. + So s/!S_ISREG/S_ISDIR/ and change some messsaging ... */ + if (S_ISDIR(statbuf.st_mode)) { DEBUG(D_tls) - debug_printf("verify certificates path is not a file: \"%s\"\n%s\n", - state->exp_tls_verify_certificates, - S_ISDIR(statbuf.st_mode) - ? " it's a directory, that's OpenSSL, this is GnuTLS" - : " (not a directory either)"); + debug_printf("verify certificates path is a dir: \"%s\"\n", + state->exp_tls_verify_certificates); log_write(0, LOG_MAIN|LOG_PANIC, - "tls_verify_certificates \"%s\" is not a file", - state->exp_tls_verify_certificates); + "tls_verify_certificates \"%s\" is a directory", + state->exp_tls_verify_certificates); return DEFER; } +#endif DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n", - state->exp_tls_verify_certificates, statbuf.st_size); + state->exp_tls_verify_certificates, statbuf.st_size); - /* If the CA cert file is empty, there's no point in loading the CRL file, - as we aren't verifying, so checking for revocation is pointless. */ - - if (statbuf.st_size > 0) + if (statbuf.st_size == 0) { - if (setit_vc) - { - cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred, - CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); - if (cert_count < 0) - { - rc = cert_count; - exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file"); - } - DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); - } + DEBUG(D_tls) + debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n"); + return OK; + } - if (setit_crl && state->tls_crl && *state->tls_crl) - { - if (state->exp_tls_crl && *state->exp_tls_crl) - { - DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); - rc = gnutls_certificate_set_x509_crl_file(state->x509_cred, - CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); - exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); - } - } - } /* statbuf.st_size */ - } /* tls_verify_certificates */ + cert_count = + +#ifdef SUPPORT_CA_DIR + (statbuf.st_mode & S_IFMT) == S_IFDIR + ? + gnutls_certificate_set_x509_trust_dir(state->x509_cred, + CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM) + : +#endif + gnutls_certificate_set_x509_trust_file(state->x509_cred, + CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM); + } + +if (cert_count < 0) + { + rc = cert_count; + exim_gnutls_err_check(US"setting certificate trust"); + } +DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count); + +if (state->tls_crl && *state->tls_crl && + state->exp_tls_crl && *state->exp_tls_crl) + { + DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl); + cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred, + CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM); + if (cert_count < 0) + { + rc = cert_count; + exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file"); + } + DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count); + } return OK; -/* also above, during verify_certificates/crl, during SNI, if unchanged */ } +/************************************************* +* Set X.509 state variables * +*************************************************/ + +/* In GnuTLS, the registered cert/key are not replaced by a later +set of a cert/key, so for SNI support we need a whole new x509_cred +structure. Which means various other non-re-expanded pieces of state +need to be re-set in the new struct, so the setting logic is pulled +out to this. + +Arguments: + state exim_gnutls_state_st * + +Returns: OK/DEFER/FAIL +*/ + +static int +tls_set_remaining_x509(exim_gnutls_state_st *state) +{ +int rc; +const host_item *host = state->host; /* macro should be reconsidered? */ + +/* Create D-H parameters, or read them from the cache file. This function does +its own SMTP error messaging. This only happens for the server, TLS D-H ignores +client-side params. */ + +if (!state->host) + { + if (!dh_server_params) + { + rc = init_server_dh(); + if (rc != OK) return rc; + } + gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); + } + +/* Link the credentials to the session. */ + +rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); +exim_gnutls_err_check(US"gnutls_credentials_set"); + +return OK; +} + /************************************************* * Initialize for GnuTLS * *************************************************/ @@ -760,6 +1022,7 @@ Arguments: cas CA certs file crl CRL file require_ciphers tls_require_ciphers setting + caller_state returned state-info structure Returns: OK/DEFER/FAIL */ @@ -786,6 +1049,19 @@ if (!exim_gnutls_base_init_done) { DEBUG(D_tls) debug_printf("GnuTLS global init required.\n"); +#ifdef HAVE_GNUTLS_PKCS11 + /* By default, gnutls_global_init will init PKCS11 support in auto mode, + which loads modules from a config file, which sounds good and may be wanted + by some sysadmin, but also means in common configurations that GNOME keyring + environment variables are used and so breaks for users calling mailq. + To prevent this, we init PKCS11 first, which is the documented approach. */ + if (!gnutls_allow_auto_pkcs11) + { + rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); + exim_gnutls_err_check(US"gnutls_pkcs11_init"); + } +#endif + rc = gnutls_global_init(); exim_gnutls_err_check(US"gnutls_global_init"); @@ -805,6 +1081,7 @@ if (host) { state = &state_client; memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); + state->tlsp = &tls_out; DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n"); rc = gnutls_init(&state->session, GNUTLS_CLIENT); } @@ -812,6 +1089,7 @@ else { state = &state_server; memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); + state->tlsp = &tls_in; DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n"); rc = gnutls_init(&state->session, GNUTLS_SERVER); } @@ -821,13 +1099,11 @@ state->host = host; state->tls_certificate = certificate; state->tls_privatekey = privatekey; +state->tls_require_ciphers = require_ciphers; state->tls_sni = sni; state->tls_verify_certificates = cas; state->tls_crl = crl; -rc = gnutls_certificate_allocate_credentials(&state->x509_cred); -exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials"); - /* This handles the variables that might get re-expanded after TLS SNI; that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */ @@ -836,34 +1112,24 @@ DEBUG(D_tls) rc = tls_expand_session_files(state); if (rc != OK) return rc; -/* Create D-H parameters, or read them from the cache file. This function does -its own SMTP error messaging. This only happens for the server, TLS D-H ignores -client-side params. */ +/* These are all other parts of the x509_cred handling, since SNI in GnuTLS +requires a new structure afterwards. */ -if (!host) - { - rc = init_server_dh(); - if (rc != OK) return rc; - gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params); - } - -/* Link the credentials to the session. */ - -rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); -exim_gnutls_err_check(US"gnutls_credentials_set"); +rc = tls_set_remaining_x509(state); +if (rc != OK) return rc; /* set SNI in client, only */ if (host) { - if (!expand_check_tlsvar(tls_sni)) + if (!expand_check(sni, US"tls_out_sni", &state->tlsp->sni)) return DEFER; - if (state->exp_tls_sni && *state->exp_tls_sni) + if (state->tlsp->sni && *state->tlsp->sni) { DEBUG(D_tls) - debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni); - sz = Ustrlen(state->exp_tls_sni); + debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni); + sz = Ustrlen(state->tlsp->sni); rc = gnutls_server_name_set(state->session, - GNUTLS_NAME_DNS, state->exp_tls_sni, sz); + GNUTLS_NAME_DNS, state->tlsp->sni, sz); exim_gnutls_err_check(US"gnutls_server_name_set"); } } @@ -872,7 +1138,7 @@ else if (state->tls_sni) "have an SNI set for a client [%s]\n", state->tls_sni); /* This is the priority string support, -http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html +http://www.gnutls.org/manual/html_node/Priority-Strings.html and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols. This was backwards incompatible, but means Exim no longer needs to track all algorithms and provide string forms for them. */ @@ -896,6 +1162,9 @@ if (state->tls_require_ciphers && *state->tls_require_ciphers) } if (want_default_priorities) { + DEBUG(D_tls) + debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", + exim_default_gnutls_priority); rc = gnutls_priority_init(&state->priority_cache, exim_default_gnutls_priority, &errpos); p = US exim_default_gnutls_priority; @@ -923,20 +1192,32 @@ if (gnutls_compat_mode) } *caller_state = state; -/* needs to happen before callbacks during handshake */ -current_global_tls_state = state; return OK; } - /************************************************* * Extract peer information * *************************************************/ /* Called from both server and client code. -Only this is allowed to set state->peerdn and we use that to detect double-calls. +Only this is allowed to set state->peerdn and state->have_set_peerdn +and we use that to detect double-calls. + +NOTE: the state blocks last while the TLS connection is up, which is fine +for logging in the server side, but for the client side, we log after teardown +in src/deliver.c. While the session is up, we can twist about states and +repoint tls_* globals, but those variables used for logging or other variable +expansion that happens _after_ delivery need to have a longer life-time. + +So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from +doing this more than once per generation of a state context. We set them in +the state context, and repoint tls_* to them. After the state goes away, the +tls_* copies of the pointers remain valid and client delivery logging is happy. + +tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues +don't apply. Arguments: state exim_gnutls_state_st * @@ -947,27 +1228,57 @@ Returns: OK/DEFER/FAIL static int peer_status(exim_gnutls_state_st *state) { +uschar cipherbuf[256]; const gnutls_datum *cert_list; -int rc; +int old_pool, rc; unsigned int cert_list_size = 0; +gnutls_protocol_t protocol; +gnutls_cipher_algorithm_t cipher; +gnutls_kx_algorithm_t kx; +gnutls_mac_algorithm_t mac; gnutls_certificate_type_t ct; gnutls_x509_crt_t crt; -uschar *dn_buf; +uschar *p, *dn_buf; size_t sz; -if (state->peerdn) +if (state->have_set_peerdn) return OK; +state->have_set_peerdn = TRUE; -state->peerdn = US"unknown"; +state->peerdn = NULL; +/* tls_cipher */ +cipher = gnutls_cipher_get(state->session); +protocol = gnutls_protocol_get_version(state->session); +mac = gnutls_mac_get(state->session); +kx = gnutls_kx_get(state->session); + +string_format(cipherbuf, sizeof(cipherbuf), + "%s:%s:%d", + gnutls_protocol_get_name(protocol), + gnutls_cipher_suite_get_name(kx, cipher, mac), + (int) gnutls_cipher_get_key_size(cipher) * 8); + +/* I don't see a way that spaces could occur, in the current GnuTLS +code base, but it was a concern in the old code and perhaps older GnuTLS +releases did return "TLS 1.0"; play it safe, just in case. */ +for (p = cipherbuf; *p != '\0'; ++p) + if (isspace(*p)) + *p = '-'; +old_pool = store_pool; +store_pool = POOL_PERM; +state->ciphersuite = string_copy(cipherbuf); +store_pool = old_pool; +state->tlsp->cipher = state->ciphersuite; + +/* tls_peerdn */ cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size); if (cert_list == NULL || cert_list_size == 0) { - state->peerdn = US"unknown (no certificate)"; DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n", cert_list, cert_list_size); - if (state->verify_requirement == VERIFY_REQUIRED) + if (state->verify_requirement >= VERIFY_REQUIRED) return tls_error(US"certificate verification failed", "no certificate received from peer", state->host); return OK; @@ -977,26 +1288,31 @@ ct = gnutls_certificate_type_get(state->session); if (ct != GNUTLS_CRT_X509) { const char *ctn = gnutls_certificate_type_get_name(ct); - state->peerdn = string_sprintf("unknown (type %s)", ctn); DEBUG(D_tls) debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn); - if (state->verify_requirement == VERIFY_REQUIRED) + if (state->verify_requirement >= VERIFY_REQUIRED) return tls_error(US"certificate verification not possible, unhandled type", ctn, state->host); return OK; } -#define exim_gnutls_peer_err(Label) do { \ - if (rc != GNUTLS_E_SUCCESS) { \ - DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", (Label), gnutls_strerror(rc)); \ - if (state->verify_requirement == VERIFY_REQUIRED) { return tls_error((Label), gnutls_strerror(rc), state->host); } \ - return OK; } } while (0) +#define exim_gnutls_peer_err(Label) \ + do { \ + if (rc != GNUTLS_E_SUCCESS) \ + { \ + DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \ + (Label), gnutls_strerror(rc)); \ + if (state->verify_requirement >= VERIFY_REQUIRED) \ + return tls_error((Label), gnutls_strerror(rc), state->host); \ + return OK; \ + } \ + } while (0) + +rc = import_cert(&cert_list[0], &crt); +exim_gnutls_peer_err(US"cert 0"); -rc = gnutls_x509_crt_init(&crt); -exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)"); +state->tlsp->peercert = state->peercert = crt; -rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER); -exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]"); sz = 0; rc = gnutls_x509_crt_get_dn(crt, NULL, &sz); if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) @@ -1007,6 +1323,7 @@ if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER) dn_buf = store_get_perm(sz); rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz); exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]"); + state->peerdn = dn_buf; return OK; @@ -1042,45 +1359,69 @@ unsigned int verify; *error = NULL; -rc = peer_status(state); -if (rc != OK) +if ((rc = peer_status(state)) != OK) { verify = GNUTLS_CERT_INVALID; - *error = "not supplied"; + *error = "certificate not supplied"; } else - { rc = gnutls_certificate_verify_peers2(state->session, &verify); - } /* Handle the result of verification. INVALID seems to be set as well as REVOKED, but leave the test for both. */ -if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0) +if (rc < 0 || + verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED) + ) { state->peer_cert_verified = FALSE; - if (*error == NULL) - *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid"; + if (!*error) + *error = verify & GNUTLS_CERT_REVOKED + ? "certificate revoked" : "certificate invalid"; DEBUG(D_tls) - debug_printf("TLS certificate verification failed (%s): peerdn=%s\n", - *error, state->peerdn); + debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n", + *error, state->peerdn ? state->peerdn : US""); - if (state->verify_requirement == VERIFY_REQUIRED) + if (state->verify_requirement >= VERIFY_REQUIRED) { - gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); + gnutls_alert_send(state->session, + GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); return FALSE; } DEBUG(D_tls) - debug_printf("TLS verify failure overriden (host in tls_try_verify_hosts)\n"); + debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n"); } + else { + if (state->exp_tls_verify_cert_hostnames) + { + int sep = 0; + uschar * list = state->exp_tls_verify_cert_hostnames; + uschar * name; + while (name = string_nextinlist(&list, &sep, NULL, 0)) + if (gnutls_x509_crt_check_hostname(state->tlsp->peercert, CS name)) + break; + if (!name) + { + DEBUG(D_tls) + debug_printf("TLS certificate verification failed: cert name mismatch\n"); + if (state->verify_requirement >= VERIFY_REQUIRED) + { + gnutls_alert_send(state->session, + GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE); + return FALSE; + } + return TRUE; + } + } state->peer_cert_verified = TRUE; - DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", state->peerdn); + DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n", + state->peerdn ? state->peerdn : US""); } -tls_peerdn = state->peerdn; +state->tlsp->peerdn = state->peerdn; return TRUE; } @@ -1095,11 +1436,20 @@ return TRUE; * gnutls_global_set_log_function() * gnutls_global_set_log_level() 0..9 */ +#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 static void exim_gnutls_logger_cb(int level, const char *message) { - DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s\n", level, message); + size_t len = strlen(message); + if (len < 1) + { + DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); + return; + } + DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, + message[len-1] == '\n' ? "" : "\n"); } +#endif /* Called after client hello, should handle SNI work. @@ -1115,6 +1465,7 @@ handshake.". For inability to get SNI information, we return 0. We only return non-zero if re-setup failed. +Only used for server-side TLS. */ static int @@ -1122,12 +1473,23 @@ exim_sni_handling_cb(gnutls_session_t session) { char sni_name[MAX_HOST_LEN]; size_t data_len = MAX_HOST_LEN; -exim_gnutls_state_st *state = current_global_tls_state; +exim_gnutls_state_st *state = &state_server; unsigned int sni_type; int rc, old_pool; rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0); -exim_gnutls_err_debugreturn0("gnutls_server_name_get()"); +if (rc != GNUTLS_E_SUCCESS) + { + DEBUG(D_tls) { + if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) + debug_printf("TLS: no SNI presented in handshake.\n"); + else + debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n", + gnutls_strerror(rc), rc); + }; + return 0; + } + if (sni_type != GNUTLS_NAME_DNS) { DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type); @@ -1141,7 +1503,7 @@ state->received_sni = string_copyn(US sni_name, data_len); store_pool = old_pool; /* We set this one now so that variable expansions below will work */ -tls_sni = state->received_sni; +state->tlsp->sni = state->received_sni; DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name, state->trigger_sni_changes ? "" : " (unused for certificate selection)"); @@ -1157,12 +1519,87 @@ if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; } -rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred); -return (rc == GNUTLS_E_SUCCESS) ? 0 : rc; +rc = tls_set_remaining_x509(state); +if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN; + +return 0; } +#ifndef DISABLE_OCSP + +static int +server_ocsp_stapling_cb(gnutls_session_t session, void * ptr, + gnutls_datum_t * ocsp_response) +{ +int ret; + +if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0) + { + DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n", + (char *)ptr); + tls_in.ocsp = OCSP_NOT_RESP; + return GNUTLS_E_NO_CERTIFICATE_STATUS; + } + +tls_in.ocsp = OCSP_VFY_NOT_TRIED; +return 0; +} + +#endif + + +#ifdef EXPERIMENTAL_EVENT +/* +We use this callback to get observability and detail-level control +for an exim TLS connection (either direction), raising a tls:cert event +for each cert in the chain presented by the peer. Any event +can deny verification. + +Return 0 for the handshake to continue or non-zero to terminate. +*/ + +static int +verify_cb(gnutls_session_t session) +{ +const gnutls_datum * cert_list; +unsigned int cert_list_size = 0; +gnutls_x509_crt_t crt; +int rc; +uschar * yield; +exim_gnutls_state_st * state = gnutls_session_get_ptr(session); + +cert_list = gnutls_certificate_get_peers(session, &cert_list_size); +if (cert_list) + while (cert_list_size--) + { + rc = import_cert(&cert_list[cert_list_size], &crt); + if (rc != GNUTLS_E_SUCCESS) + { + DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n", + cert_list_size, gnutls_strerror(rc)); + break; + } + + state->tlsp->peercert = crt; + if ((yield = event_raise(state->event_action, + US"tls:cert", string_sprintf("%d", cert_list_size)))) + { + log_write(0, LOG_MAIN, + "SSL verify denied by event-action: depth=%d: %s", + cert_list_size, yield); + return 1; /* reject */ + } + state->tlsp->peercert = NULL; + } + +return 0; +} + +#endif + + /* ------------------------------------------------------------------------ */ /* Exported functions */ @@ -1195,9 +1632,7 @@ const char *error; exim_gnutls_state_st *state = NULL; /* Check for previous activation */ -/* nb: this will not be TLS callout safe, needs reworking as part of that. */ - -if (tls_active >= 0) +if (tls_in.active >= 0) { tls_error(US"STARTTLS received after TLS started", "", NULL); smtp_printf("554 Already in TLS\r\n"); @@ -1219,23 +1654,35 @@ optional, set up appropriately. */ if (verify_check_host(&tls_verify_hosts) == OK) { - DEBUG(D_tls) debug_printf("TLS: a client certificate will be required.\n"); + DEBUG(D_tls) + debug_printf("TLS: a client certificate will be required.\n"); state->verify_requirement = VERIFY_REQUIRED; gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); } else if (verify_check_host(&tls_try_verify_hosts) == OK) { - DEBUG(D_tls) debug_printf("TLS: a client certificate will be requested but not required.\n"); + DEBUG(D_tls) + debug_printf("TLS: a client certificate will be requested but not required.\n"); state->verify_requirement = VERIFY_OPTIONAL; gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); } else { - DEBUG(D_tls) debug_printf("TLS: a client certificate will not be requested.\n"); + DEBUG(D_tls) + debug_printf("TLS: a client certificate will not be requested.\n"); state->verify_requirement = VERIFY_NONE; gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); } +#ifdef EXPERIMENTAL_EVENT +if (event_action) + { + state->event_action = event_action; + gnutls_session_set_ptr(state->session, state); + gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); + } +#endif + /* Register SNI handling; always, even if not in tls_certificate, so that the expansion variable $tls_sni is always available. */ @@ -1248,7 +1695,7 @@ make them disconnect. We need to have an explicit fflush() here, to force out the response. Other smtp_printf() calls do not need it, because in non-TLS mode, the fflush() happens when smtp_getc() is called. */ -if (!tls_on_connect) +if (!state->tlsp->on_connect) { smtp_printf("220 TLS go ahead\r\n"); fflush(smtp_out); @@ -1258,8 +1705,8 @@ if (!tls_on_connect) that the GnuTLS library doesn't. */ gnutls_transport_set_ptr2(state->session, - (gnutls_transport_ptr)fileno(smtp_in), - (gnutls_transport_ptr)fileno(smtp_out)); + (gnutls_transport_ptr)(long) fileno(smtp_in), + (gnutls_transport_ptr)(long) fileno(smtp_out)); state->fd_in = fileno(smtp_in); state->fd_out = fileno(smtp_out); @@ -1268,7 +1715,8 @@ if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout); do { rc = gnutls_handshake(state->session); - } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); + } while ((rc == GNUTLS_E_AGAIN) || + (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); alarm(0); if (rc != GNUTLS_E_SUCCESS) @@ -1292,22 +1740,17 @@ DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); /* Verify after the fact */ -if (state->verify_requirement != VERIFY_NONE) +if ( state->verify_requirement != VERIFY_NONE + && !verify_certificate(state, &error)) { - if (!verify_certificate(state, &error)) + if (state->verify_requirement != VERIFY_OPTIONAL) { - if (state->verify_requirement == VERIFY_OPTIONAL) - { - DEBUG(D_tls) - debug_printf("TLS: continuing on only because verification was optional, after: %s\n", - error); - } - else - { - tls_error(US"certificate verification failed", error, NULL); - return FAIL; - } + tls_error(US"certificate verification failed", error, NULL); + return FAIL; } + DEBUG(D_tls) + debug_printf("TLS: continuing on only because verification was optional, after: %s\n", + error); } /* Figure out peer DN, and if authenticated, etc. */ @@ -1336,6 +1779,20 @@ return OK; +static void +tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state, + smtp_transport_options_block * ob) +{ +if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK) + { + state->exp_tls_verify_cert_hostnames = host->name; + DEBUG(D_tls) + debug_printf("TLS: server cert verification includes hostname: \"%s\".\n", + state->exp_tls_verify_cert_hostnames); + } +} + + /************************************************* * Start a TLS session in a client * *************************************************/ @@ -1346,14 +1803,7 @@ Arguments: fd the fd of the connection host connected host (for messages) addr the first address (not used) - dhparam DH parameter file (ignored, we're a client) - certificate certificate file - privatekey private key file - sni TLS SNI to send to remote host - verify_certs file for certificate verify - verify_crl CRL for verify - require_ciphers list of allowed ciphers or NULL - timeout startup timeout + tb transport (always smtp) Returns: OK/DEFER/FAIL (because using common functions), but for a client, DEFER and FAIL have the same meaning @@ -1361,51 +1811,124 @@ Returns: OK/DEFER/FAIL (because using common functions), int tls_client_start(int fd, host_item *host, - address_item *addr ARG_UNUSED, uschar *dhparam ARG_UNUSED, - uschar *certificate, uschar *privatekey, uschar *sni, - uschar *verify_certs, uschar *verify_crl, - uschar *require_ciphers, int timeout) + address_item *addr ARG_UNUSED, + transport_instance *tb +#ifdef EXPERIMENTAL_DANE + , dne_answer * unused_tlsa_dnsa +#endif + ) { +smtp_transport_options_block *ob = + (smtp_transport_options_block *)tb->options_block; int rc; const char *error; exim_gnutls_state_st *state = NULL; +#ifndef DISABLE_OCSP +BOOL require_ocsp = + verify_check_given_host(&ob->hosts_require_ocsp, host) == OK; +BOOL request_ocsp = require_ocsp ? TRUE + : verify_check_given_host(&ob->hosts_request_ocsp, host) == OK; +#endif DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd); -rc = tls_init(host, certificate, privatekey, - sni, verify_certs, verify_crl, require_ciphers, &state); -if (rc != OK) return rc; +if ((rc = tls_init(host, ob->tls_certificate, ob->tls_privatekey, + ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl, + ob->tls_require_ciphers, &state)) != OK) + return rc; + + { + int dh_min_bits = ob->tls_dh_min_bits; + if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS) + { + DEBUG(D_tls) + debug_printf("WARNING: tls_dh_min_bits far too low," + " clamping %d up to %d\n", + dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS); + dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS; + } -gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS); + DEBUG(D_tls) debug_printf("Setting D-H prime minimum" + " acceptable bits to %d\n", + dh_min_bits); + gnutls_dh_set_prime_bits(state->session, dh_min_bits); + } + +/* Stick to the old behaviour for compatibility if tls_verify_certificates is +set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only +the specified host patterns if one of them is defined */ -if (verify_certs == NULL) +if ( ( state->exp_tls_verify_certificates + && !ob->tls_verify_hosts + && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts) + ) + || verify_check_given_host(&ob->tls_verify_hosts, host) == OK + ) { - DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n"); - state->verify_requirement = VERIFY_NONE; - /* we still ask for it, to log it, etc */ + tls_client_setup_hostname_checks(host, state, ob); + DEBUG(D_tls) + debug_printf("TLS: server certificate verification required.\n"); + state->verify_requirement = VERIFY_REQUIRED; + gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); + } +else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK) + { + tls_client_setup_hostname_checks(host, state, ob); + DEBUG(D_tls) + debug_printf("TLS: server certificate verification optional.\n"); + state->verify_requirement = VERIFY_OPTIONAL; gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST); } else { - DEBUG(D_tls) debug_printf("TLS: server certificate verification required\n"); - state->verify_requirement = VERIFY_REQUIRED; - gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE); + DEBUG(D_tls) + debug_printf("TLS: server certificate verification not required.\n"); + state->verify_requirement = VERIFY_NONE; + gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE); } -gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd); +#ifndef DISABLE_OCSP + /* supported since GnuTLS 3.1.3 */ +if (request_ocsp) + { + DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n"); + if ((rc = gnutls_ocsp_status_request_enable_client(state->session, + NULL, 0, NULL)) != OK) + return tls_error(US"cert-status-req", + gnutls_strerror(rc), state->host); + tls_out.ocsp = OCSP_NOT_RESP; + } +#endif + +#ifdef EXPERIMENTAL_EVENT +if (tb->event_action) + { + state->event_action = tb->event_action; + gnutls_session_set_ptr(state->session, state); + gnutls_certificate_set_verify_function(state->x509_cred, verify_cb); + } +#endif + +gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)(long) fd); state->fd_in = fd; state->fd_out = fd; +DEBUG(D_tls) debug_printf("about to gnutls_handshake\n"); /* There doesn't seem to be a built-in timeout on connection. */ sigalrm_seen = FALSE; -alarm(timeout); +alarm(ob->command_timeout); do { rc = gnutls_handshake(state->session); - } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED)); + } while ((rc == GNUTLS_E_AGAIN) || + (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen)); alarm(0); +if (rc != GNUTLS_E_SUCCESS) + return tls_error(US"gnutls_handshake", + sigalrm_seen ? "timed out" : gnutls_strerror(rc), state->host); + DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n"); /* Verify late */ @@ -1414,12 +1937,43 @@ if (state->verify_requirement != VERIFY_NONE && !verify_certificate(state, &error)) return tls_error(US"certificate verification failed", error, state->host); +#ifndef DISABLE_OCSP +if (require_ocsp) + { + DEBUG(D_tls) + { + gnutls_datum_t stapling; + gnutls_ocsp_resp_t resp; + gnutls_datum_t printed; + if ( (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0 + && (rc= gnutls_ocsp_resp_init(&resp)) == 0 + && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0 + && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0 + ) + { + debug_printf("%.4096s", printed.data); + gnutls_free(printed.data); + } + else + (void) tls_error(US"ocsp decode", gnutls_strerror(rc), state->host); + } + + if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0) + { + tls_out.ocsp = OCSP_FAILED; + return tls_error(US"certificate status check failed", NULL, state->host); + } + DEBUG(D_tls) debug_printf("Passed OCSP checking\n"); + tls_out.ocsp = OCSP_VFIED; + } +#endif + /* Figure out peer DN, and if authenticated, etc. */ -rc = peer_status(state); -if (rc != OK) return rc; +if ((rc = peer_status(state)) != OK) + return rc; -/* Sets various Exim expansion variables; always safe within server */ +/* Sets various Exim expansion variables; may need to adjust for ACL callouts */ extract_exim_vars_from_tls_state(state); @@ -1442,11 +1996,11 @@ Returns: nothing */ void -tls_close(BOOL shutdown) +tls_close(BOOL is_server, BOOL shutdown) { -exim_gnutls_state_st *state = current_global_tls_state; +exim_gnutls_state_st *state = is_server ? &state_server : &state_client; -if (tls_active < 0) return; /* TLS was not active */ +if (!state->tlsp || state->tlsp->active < 0) return; /* TLS was not active */ if (shutdown) { @@ -1456,6 +2010,7 @@ if (shutdown) gnutls_deinit(state->session); +state->tlsp->active = -1; memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init)); if ((state_server.session == NULL) && (state_client.session == NULL)) @@ -1464,7 +2019,6 @@ if ((state_server.session == NULL) && (state_client.session == NULL)) exim_gnutls_base_init_done = FALSE; } -tls_active = -1; } @@ -1476,6 +2030,7 @@ tls_active = -1; /* This gets the next byte from the TLS input buffer. If the buffer is empty, it refills the buffer via the GnuTLS reading function. +Only used by the server-side TLS. This feeds DKIM and should be used for all message-body reads. @@ -1486,7 +2041,7 @@ Returns: the next character or EOF int tls_getc(void) { -exim_gnutls_state_st *state = current_global_tls_state; +exim_gnutls_state_st *state = &state_server; if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) { ssize_t inbytes; @@ -1515,12 +2070,13 @@ if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm) gnutls_deinit(state->session); state->session = NULL; - tls_active = -1; - tls_bits = 0; - tls_certificate_verified = FALSE; + state->tlsp->active = -1; + state->tlsp->bits = 0; + state->tlsp->certificate_verified = FALSE; tls_channelbinding_b64 = NULL; - tls_cipher = NULL; - tls_peerdn = NULL; + state->tlsp->cipher = NULL; + state->tlsp->peercert = NULL; + state->tlsp->peerdn = NULL; return smtp_getc(); } @@ -1554,6 +2110,7 @@ return state->xfer_buffer[state->xfer_buffer_lwm++]; /* This does not feed DKIM, so if the caller uses this for reading message body, then the caller must feed DKIM. + Arguments: buff buffer of data len size of buffer @@ -1563,9 +2120,9 @@ Returns: the number of bytes read */ int -tls_read(uschar *buff, size_t len) +tls_read(BOOL is_server, uschar *buff, size_t len) { -exim_gnutls_state_st *state = current_global_tls_state; +exim_gnutls_state_st *state = is_server ? &state_server : &state_client; ssize_t inbytes; if (len > INT_MAX) @@ -1601,6 +2158,7 @@ return -1; /* Arguments: + is_server channel specifier buff buffer of data len number of bytes @@ -1609,11 +2167,11 @@ Returns: the number of bytes after a successful write, */ int -tls_write(const uschar *buff, size_t len) +tls_write(BOOL is_server, const uschar *buff, size_t len) { ssize_t outbytes; size_t left = len; -exim_gnutls_state_st *state = current_global_tls_state; +exim_gnutls_state_st *state = is_server ? &state_server : &state_client; DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left); while (left > 0) @@ -1667,6 +2225,7 @@ Arguments: Returns a random number in range [0, max-1] */ +#ifdef HAVE_GNUTLS_RND int vaguely_random_number(int max) { @@ -1704,6 +2263,78 @@ for (p = smallbuf; needed_len; --needed_len, ++p) * smooth distribution and cares enough then they should submit a patch then. */ return r % max; } +#else /* HAVE_GNUTLS_RND */ +int +vaguely_random_number(int max) +{ + return vaguely_random_number_fallback(max); +} +#endif /* HAVE_GNUTLS_RND */ + + + + +/************************************************* +* Let tls_require_ciphers be checked at startup * +*************************************************/ + +/* The tls_require_ciphers option, if set, must be something which the +library can parse. + +Returns: NULL on success, or error message +*/ + +uschar * +tls_validate_require_cipher(void) +{ +int rc; +uschar *expciphers = NULL; +gnutls_priority_t priority_cache; +const char *errpos; + +#define validate_check_rc(Label) do { \ + if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \ + return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0) +#define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0) + +if (exim_gnutls_base_init_done) + log_write(0, LOG_MAIN|LOG_PANIC, + "already initialised GnuTLS, Exim developer bug"); + +#ifdef HAVE_GNUTLS_PKCS11 +if (!gnutls_allow_auto_pkcs11) + { + rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL); + validate_check_rc(US"gnutls_pkcs11_init"); + } +#endif +rc = gnutls_global_init(); +validate_check_rc(US"gnutls_global_init()"); +exim_gnutls_base_init_done = TRUE; + +if (!(tls_require_ciphers && *tls_require_ciphers)) + return_deinit(NULL); + +if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers)) + return_deinit(US"failed to expand tls_require_ciphers"); + +if (!(expciphers && *expciphers)) + return_deinit(NULL); + +DEBUG(D_tls) + debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers); + +rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos); +validate_check_rc(string_sprintf( + "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"", + expciphers, errpos - CS expciphers, errpos)); + +#undef return_deinit +#undef validate_check_rc +gnutls_global_deinit(); + +return NULL; +} @@ -1727,4 +2358,6 @@ fprintf(f, "Library version: GnuTLS: Compile: %s\n" gnutls_check_version(NULL)); } +/* vi: aw ai sw=2 +*/ /* End of tls-gnu.c */