X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=src%2Fsrc%2Ftls.c;h=a12211859a8709238cffe21c95ac8685de445400;hb=97a60b65cd60d34c9717c698efbdff9332aa4f1b;hp=796bc6d61649c482fa7846d8831a36a27311f31d;hpb=de517fd3061ee343cd36d05587c915f617318671;p=user%2Fhenk%2Fcode%2Fexim.git diff --git a/src/src/tls.c b/src/src/tls.c index 796bc6d61..a12211859 100644 --- a/src/src/tls.c +++ b/src/src/tls.c @@ -3,6 +3,7 @@ *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2018 */ +/* Copyright (c) The Exim Maintainers 2020 */ /* See the file NOTICE for conditions of use and distribution. */ /* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is @@ -35,6 +36,18 @@ functions from the OpenSSL or GNU TLS libraries. */ #ifndef MACRO_PREDEF +static void tls_per_lib_daemon_init(void); +static void tls_per_lib_daemon_tick(void); +static void tls_server_creds_init(void); +static void tls_server_creds_invalidate(void); +static void tls_client_creds_init(transport_instance *, BOOL); +static void tls_client_creds_invalidate(transport_instance *); +static void tls_daemon_creds_reload(void); +static BOOL opt_set_and_noexpand(const uschar *); +static BOOL opt_unset_or_noexpand(const uschar *); + + + /* This module is compiled only when it is specifically requested in the build-time configuration. However, some compilers don't like compiling empty modules, so keep them happy with a dummy when skipping the rest. Make it @@ -44,7 +57,9 @@ loops. */ #ifdef DISABLE_TLS static void dummy(int x) { dummy(x-1); } -#else +#else /* most of the rest of the file */ + +const exim_tlslib_state null_tls_preload = {0}; /* Static variables that are used for buffering data by both sets of functions and the common functions below. @@ -61,8 +76,6 @@ static int ssl_xfer_eof = FALSE; static BOOL ssl_xfer_error = FALSE; #endif -uschar *tls_channelbinding_b64 = NULL; - /************************************************* * Expand string; give error on failure * @@ -97,6 +110,154 @@ return TRUE; } +#ifdef EXIM_HAVE_INOTIFY +/* Add the directory for a filename to the inotify handle, creating that if +needed. This is enough to see changes to files in that dir. +Return boolean success. + +The word "system" fails, which is on the safe side as we don't know what +directory it implies nor if the TLS library handles a watch for us. + +The string "system,cache" is recognised and explicitly accepted without +setting a watch. This permits the system CA bundle to be cached even though +we have no way to tell when it gets modified by an update. + +We *might* try to run "openssl version -d" and set watches on the dir +indicated in its output, plus the "certs" subdir of it (following +synlimks for both). But this is undocumented even for OpenSSL, and +who knows what GnuTLS might be doing. + +A full set of caching including the CAs takes 35ms output off of the +server tls_init() (GnuTLS, Fedora 32, 2018-class x86_64 laptop hardware). +*/ +static BOOL +tls_set_one_watch(const uschar * filename) +{ +uschar * s; + +if (Ustrcmp(filename, "system,cache") == 0) return TRUE; + +if (!(s = Ustrrchr(filename, '/'))) return FALSE; +s = string_copyn(filename, s - filename); +DEBUG(D_tls) debug_printf("watch dir '%s'\n", s); + +if (inotify_add_watch(tls_watch_fd, CCS s, + IN_ONESHOT | IN_CLOSE_WRITE | IN_DELETE | IN_DELETE_SELF + | IN_MOVED_FROM | IN_MOVED_TO | IN_MOVE_SELF) >= 0) + return TRUE; +DEBUG(D_tls) debug_printf("add_watch: %s\n", strerror(errno)); +return FALSE; +} + + +/* Create an inotify facility if needed. +Then set watches on the dir containing the given file or (optionally) +list of files. Return boolean success. */ + +static BOOL +tls_set_watch(const uschar * filename, BOOL list) +{ +rmark r; +BOOL rc = FALSE; + +if (tls_watch_fd < 0 && (tls_watch_fd = inotify_init1(O_CLOEXEC)) < 0) + { + DEBUG(D_tls) debug_printf("inotify_init: %s\n", strerror(errno)); + return FALSE; + } + +if (!filename || !*filename) return TRUE; + +r = store_mark(); + +if (list) + { + int sep = 0; + for (uschar * s; s = string_nextinlist(&filename, &sep, NULL, 0); ) + if (!(rc = tls_set_one_watch(s))) break; + } +else + rc = tls_set_one_watch(filename); + +store_reset(r); +return rc; +} + + +/* Called, after a delay for multiple file ops to get done, from +the daemon when any of the watches added (above) fire. + +Dump the set of watches and arrange to reload cached creds (which +will set up new watches). */ + +static void +tls_watch_triggered(void) +{ +DEBUG(D_tls) debug_printf("watch triggered\n"); +close(tls_watch_fd); +tls_watch_fd = -1; + +tls_daemon_creds_reload(); +} +#endif /* EXIM_HAVE_INOTIFY */ + + +void +tls_client_creds_reload(BOOL watch) +{ +for(transport_instance * t = transports; t; t = t->next) + if (Ustrcmp(t->driver_name, "smtp") == 0) + { + tls_client_creds_invalidate(t); + tls_client_creds_init(t, watch); + } +} + +static void +tls_daemon_creds_reload(void) +{ +tls_server_creds_invalidate(); +tls_server_creds_init(); + +tls_client_creds_reload(TRUE); +} + + +/* Utility predicates for use by the per-library code */ +static BOOL +opt_set_and_noexpand(const uschar * opt) +{ return opt && *opt && Ustrchr(opt, '$') == NULL; } + +static BOOL +opt_unset_or_noexpand(const uschar * opt) +{ return !opt || Ustrchr(opt, '$') == NULL; } + + + +/* Called every time round the daemon loop */ + +void +tls_daemon_tick(void) +{ +tls_per_lib_daemon_tick(); +#ifdef EXIM_HAVE_INOTIFY +if (tls_watch_trigger_time && time(NULL) >= tls_watch_trigger_time + 5) + { + tls_watch_trigger_time = 0; + tls_watch_triggered(); + } +#endif +} + +/* Called once at daemon startup */ + +void +tls_daemon_init(void) +{ +tls_per_lib_daemon_init(); +} + + /************************************************* * Timezone environment flipping * *************************************************/ @@ -369,6 +530,113 @@ else if ((subjdn = tls_cert_subject(cert, NULL))) } return FALSE; } + + +/* Environment cleanup: The GnuTLS library uses SSLKEYLOGFILE in the environment +and writes a file by that name. Our OpenSSL code does the same, using keying +info from the library API. +The GnuTLS support only works if exim is run by root, not taking advantage of +the setuid bit. +You can use either the external environment (modulo the keep_environment config) +or the add_environment config option for SSLKEYLOGFILE; the latter takes +precedence. + +If the path is absolute, require it starts with the spooldir; otherwise delete +the env variable. If relative, prefix the spooldir. +*/ +void +tls_clean_env(void) +{ +uschar * path = US getenv("SSLKEYLOGFILE"); +if (path) + if (!*path) + unsetenv("SSLKEYLOGFILE"); + else if (*path != '/') + { + DEBUG(D_tls) + debug_printf("prepending spooldir to env SSLKEYLOGFILE\n"); + setenv("SSLKEYLOGFILE", CCS string_sprintf("%s/%s", spool_directory, path), 1); + } + else if (Ustrncmp(path, spool_directory, Ustrlen(spool_directory)) != 0) + { + DEBUG(D_tls) + debug_printf("removing env SSLKEYLOGFILE=%s: not under spooldir\n", path); + unsetenv("SSLKEYLOGFILE"); + } +} + +/************************************************* +* Drop privs for checking TLS config * +*************************************************/ + +/* We want to validate TLS options during readconf, but do not want to be +root when we call into the TLS library, in case of library linkage errors +which cause segfaults; before this check, those were always done as the Exim +runtime user and it makes sense to continue with that. + +Assumes: tls_require_ciphers has been set, if it will be + exim_user has been set, if it will be + exim_group has been set, if it will be + +Returns: bool for "okay"; false will cause caller to immediately exit. +*/ + +BOOL +tls_dropprivs_validate_require_cipher(BOOL nowarn) +{ +const uschar *errmsg; +pid_t pid; +int rc, status; +void (*oldsignal)(int); + +/* If TLS will never be used, no point checking ciphers */ + +if ( !tls_advertise_hosts + || !*tls_advertise_hosts + || Ustrcmp(tls_advertise_hosts, ":") == 0 + ) + return TRUE; +else if (!nowarn && !tls_certificate) + log_write(0, LOG_MAIN, + "Warning: No server certificate defined; will use a selfsigned one.\n" + " Suggested action: either install a certificate or change tls_advertise_hosts option"); + +oldsignal = signal(SIGCHLD, SIG_DFL); + +fflush(NULL); +if ((pid = exim_fork(US"cipher-validate")) < 0) + log_write(0, LOG_MAIN|LOG_PANIC_DIE, "fork failed for TLS check"); + +if (pid == 0) + { + /* in some modes, will have dropped privilege already */ + if (!geteuid()) + exim_setugid(exim_uid, exim_gid, FALSE, + US"calling tls_validate_require_cipher"); + + if ((errmsg = tls_validate_require_cipher())) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "tls_require_ciphers invalid: %s", errmsg); + fflush(NULL); + exim_underbar_exit(EXIT_SUCCESS); + } + +do { + rc = waitpid(pid, &status, 0); +} while (rc < 0 && errno == EINTR); + +DEBUG(D_tls) + debug_printf("tls_validate_require_cipher child %d ended: status=0x%x\n", + (int)pid, status); + +signal(SIGCHLD, oldsignal); + +return status == 0; +} + + + + #endif /*!DISABLE_TLS*/ #endif /*!MACRO_PREDEF*/