X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/6a9cf7f890226aa085842cd3d94b13e78ea31637..a85c067ba6c6940512cf57ec213277a370d87e70:/src/src/tls.c diff --git a/src/src/tls.c b/src/src/tls.c index ffcc8598c..9e20b5bca 100644 --- a/src/src/tls.c +++ b/src/src/tls.c @@ -2,9 +2,10 @@ * Exim - an Internet mail transport agent * *************************************************/ +/* Copyright (c) The Exim Maintainers 2020 - 2022 */ /* Copyright (c) University of Cambridge 1995 - 2018 */ -/* Copyright (c) The Exim Maintainers 2020 */ /* See the file NOTICE for conditions of use and distribution. */ +/* SPDX-License-Identifier: GPL-2.0-only */ /* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is based on a patch that was originally contributed by Steve Haslam. It was @@ -25,6 +26,11 @@ functions from the OpenSSL or GNU TLS libraries. */ #endif +/* Forward decl. */ +static void tls_client_resmption_key(tls_support *, smtp_connect_args *, + smtp_transport_options_block *); + + #if defined(MACRO_PREDEF) && !defined(DISABLE_TLS) # include "macro_predef.h" # ifdef USE_GNUTLS @@ -38,10 +44,13 @@ functions from the OpenSSL or GNU TLS libraries. */ static void tls_per_lib_daemon_init(void); static void tls_per_lib_daemon_tick(void); -static void tls_server_creds_init(void); +static unsigned 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 *); @@ -73,6 +82,13 @@ static int ssl_xfer_eof = FALSE; static BOOL ssl_xfer_error = FALSE; #endif +#ifdef EXIM_HAVE_KEVENT +# define KEV_SIZE 16 /* Eight file,dir pairs */ +static struct kevent kev[KEV_SIZE]; +static int kev_used = 0; +#endif + +static unsigned tls_creds_expire = 0; /************************************************* * Expand string; give error on failure * @@ -107,7 +123,7 @@ return TRUE; } -#ifdef EXIM_HAVE_INOTIFY +#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT) /* 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. @@ -118,33 +134,129 @@ 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. +The call chain for OpenSSL uses a (undocumented) call into the library +to discover the actual file. We don't know what GnuTLS uses. 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) +# ifdef EXIM_HAVE_INOTIFY { +uschar buf[PATH_MAX]; +ssize_t len; uschar * s; if (Ustrcmp(filename, "system,cache") == 0) return TRUE; - if (!(s = Ustrrchr(filename, '/'))) return FALSE; -s = string_copyn(filename, s - filename); + +for (unsigned loop = 20; + (len = readlink(CCS filename, CS buf, sizeof(buf))) >= 0; ) + { /* a symlink */ + if (--loop == 0) { errno = ELOOP; return FALSE; } + filename = buf[0] == '/' + ? string_copyn(buf, (unsigned)len) /* mem released by tls_set_watch */ + : string_sprintf("%.*s/%.*s", (int)(s - filename), filename, (int)len, buf); + s = Ustrrchr(filename, '/'); + } +if (errno != EINVAL) + return FALSE; /* other error */ + +/* not a symlink */ +s = string_copyn(filename, s - filename); /* mem released by tls_set_watch */ + 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)); +DEBUG(D_tls) debug_printf("notify_add_watch: %s\n", strerror(errno)); +return FALSE; +} +# endif +# ifdef EXIM_HAVE_KEVENT +{ +uschar * s, * t; +int fd1, fd2, i, j, cnt = 0; +struct stat sb; +#ifdef OpenBSD +struct kevent k_dummy; +struct timespec ts = {0}; +#endif + +errno = 0; +if (Ustrcmp(filename, "system,cache") == 0) return TRUE; + +for (;;) + { + if (kev_used > KEV_SIZE-2) { s = US"out of kev space"; goto bad; } + if (!(s = Ustrrchr(filename, '/'))) return FALSE; + s = string_copyn(filename, s - filename); /* mem released by tls_set_watch */ + + /* The dir open will fail if there is a symlink on the path. Fine; it's too + much effort to handle all possible cases; just refuse the preload. */ + + if ((fd2 = open(CCS s, O_RDONLY | O_NOFOLLOW)) < 0) { s = US"open dir"; goto bad; } + + if ((lstat(CCS filename, &sb)) < 0) { s = US"lstat"; goto bad; } + if (!S_ISLNK(sb.st_mode)) + { + if ((fd1 = open(CCS filename, O_RDONLY | O_NOFOLLOW)) < 0) + { s = US"open file"; goto bad; } + DEBUG(D_tls) debug_printf("watch file '%s':\t%d\n", filename, fd1); + EV_SET(&kev[kev_used++], + (uintptr_t)fd1, + EVFILT_VNODE, + EV_ADD | EV_ENABLE | EV_ONESHOT, + NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND + | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE, + 0, + NULL); + cnt++; + } + DEBUG(D_tls) debug_printf("watch dir '%s':\t%d\n", s, fd2); + EV_SET(&kev[kev_used++], + (uintptr_t)fd2, + EVFILT_VNODE, + EV_ADD | EV_ENABLE | EV_ONESHOT, + NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND + | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE, + 0, + NULL); + cnt++; + + if (!(S_ISLNK(sb.st_mode))) break; + + t = store_get(1024, GET_UNTAINTED); + Ustrncpy(t, s, 1022); + j = Ustrlen(s); + t[j++] = '/'; + if ((i = readlink(CCS filename, (void *)(t+j), 1023-j)) < 0) { s = US"readlink"; goto bad; } + filename = t; + *(t += i+j) = '\0'; + store_release_above(t+1); + } + +#ifdef OpenBSD +if (kevent(tls_watch_fd, &kev[kev_used-cnt], cnt, &k_dummy, 1, &ts) >= 0) + return TRUE; +#else +if (kevent(tls_watch_fd, &kev[kev_used-cnt], cnt, NULL, 0, NULL) >= 0) + return TRUE; +#endif +s = US"kevent"; + +bad: +DEBUG(D_tls) + if (errno) + debug_printf("%s: %s: %s\n", __FUNCTION__, s, strerror(errno)); + else + debug_printf("%s: %s\n", __FUNCTION__, s); return FALSE; } +# endif /*EXIM_HAVE_KEVENT*/ /* Create an inotify facility if needed. @@ -157,13 +269,23 @@ 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; +if (Ustrncmp(filename, "system", 6) == 0) return TRUE; + +DEBUG(D_tls) debug_printf("tls_set_watch: '%s'\n", filename); + +if ( tls_watch_fd < 0 +# ifdef EXIM_HAVE_INOTIFY + && (tls_watch_fd = inotify_init1(O_CLOEXEC)) < 0 +# endif +# ifdef EXIM_HAVE_KEVENT + && (tls_watch_fd = kqueue()) < 0 +# endif + ) + { + DEBUG(D_tls) debug_printf("inotify_init: %s\n", strerror(errno)); + return FALSE; + } r = store_mark(); @@ -177,10 +299,26 @@ else rc = tls_set_one_watch(filename); store_reset(r); +if (!rc) DEBUG(D_tls) debug_printf("tls_set_watch() fail on '%s': %s\n", filename, strerror(errno)); return rc; } +void +tls_watch_discard_event(int fd) +{ +#ifdef EXIM_HAVE_INOTIFY +(void) read(fd, big_buffer, big_buffer_size); +#endif +#ifdef EXIM_HAVE_KEVENT +struct kevent kev; +struct timespec t = {0}; +(void) kevent(fd, NULL, 0, &kev, 1, &t); +#endif +} +#endif /*EXIM_HAVE_INOTIFY*/ + + void tls_client_creds_reload(BOOL watch) { @@ -192,30 +330,44 @@ for(transport_instance * t = transports; t; t = t->next) } } -static void -tls_daemon_creds_reload(void) -{ -tls_server_creds_invalidate(); -tls_server_creds_init(); -tls_client_creds_reload(TRUE); -} +void +tls_watch_invalidate(void) +{ +if (tls_watch_fd < 0) return; +#ifdef EXIM_HAVE_KEVENT +/* Close the files we had open for kevent */ +for (int i = 0; i < kev_used; i++) + { + DEBUG(D_tls) debug_printf("closing watch fd: %d\n", (int) kev[i].ident); + (void) close((int) kev[i].ident); + kev[i].ident = (uintptr_t)-1; + } +kev_used = 0; +#endif -/* Called, after a delay for multiple file ops to get done, from -the daemon when any of the watches added (above) fire. +close(tls_watch_fd); +tls_watch_fd = -1; +} -Dump the set of watches and arrange to reload cached creds (which -will set up new watches). */ static void -tls_watch_triggered(void) +tls_daemon_creds_reload(void) { -DEBUG(D_tls) debug_printf("watch triggered\n"); -close(tls_watch_fd); -tls_watch_fd = -1; +unsigned lifetime; + +#ifdef EXIM_HAVE_KEVENT +tls_watch_invalidate(); +#endif + +tls_server_creds_invalidate(); -tls_daemon_creds_reload(); +/* _expire is for a time-limited selfsign server cert */ +tls_creds_expire = (lifetime = tls_server_creds_init()) + ? time(NULL) + lifetime : 0; + +tls_client_creds_reload(TRUE); } @@ -228,22 +380,47 @@ static BOOL opt_unset_or_noexpand(const uschar * opt) { return !opt || Ustrchr(opt, '$') == NULL; } -#endif /* EXIM_HAVE_INOTIFY */ -/* Called every time round the daemon loop */ +/* Called every time round the daemon loop. -void +If we reloaded fd-watcher, return the old watch fd +having modified the global for the new one. Otherwise +return -1. +*/ + +int tls_daemon_tick(void) { +int old_watch_fd = tls_watch_fd; + tls_per_lib_daemon_tick(); -#ifdef EXIM_HAVE_INOTIFY -if (tls_watch_trigger_time && time(NULL) >= tls_watch_trigger_time + 5) +#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT) +if (tls_creds_expire && time(NULL) >= tls_creds_expire) + { + /* The server cert is a selfsign, with limited lifetime. Dump it and + generate a new one. Reload the rest of the creds also as the machinery + is all there. */ + + DEBUG(D_tls) debug_printf("selfsign cert rotate\n"); + tls_creds_expire = 0; + tls_daemon_creds_reload(); + return old_watch_fd; + } +else if (tls_watch_trigger_time && time(NULL) >= tls_watch_trigger_time + 5) { - tls_watch_trigger_time = 0; - tls_watch_triggered(); + /* 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). */ + + DEBUG(D_tls) debug_printf("watch triggered\n"); + tls_watch_trigger_time = tls_creds_expire = 0; + tls_daemon_creds_reload(); + return old_watch_fd; } #endif +return -1; } /* Called once at daemon startup */ @@ -316,6 +493,9 @@ Returns: the character int tls_ungetc(int ch) { +if (ssl_xfer_buffer_lwm <= 0) + log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in tls_ungetc"); + ssl_xfer_buffer[--ssl_xfer_buffer_lwm] = ch; return ch; } @@ -528,7 +708,6 @@ 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. @@ -634,6 +813,45 @@ return status == 0; +static void +tls_client_resmption_key(tls_support * tlsp, smtp_connect_args * conn_args, + smtp_transport_options_block * ob) +{ +#ifndef DISABLE_TLS_RESUME +hctx * h = &tlsp->resume_hctx; +blob b; +gstring * g; + +DEBUG(D_tls) if (conn_args->host_lbserver) + debug_printf("TLS: lbserver '%s'\n", conn_args->host_lbserver); + +# ifdef EXIM_HAVE_SHA2 +exim_sha_init(h, HASH_SHA2_256); +# else +exim_sha_init(h, HASH_SHA1); +# endif +exim_sha_update_string(h, conn_args->host_lbserver); +# ifdef SUPPORT_DANE +if (conn_args->dane) + exim_sha_update(h, CUS &conn_args->tlsa_dnsa, sizeof(dns_answer)); +# endif +exim_sha_update_string(h, conn_args->host->address); +exim_sha_update(h, CUS &conn_args->host->port, sizeof(conn_args->host->port)); +exim_sha_update_string(h, conn_args->sending_ip_address); +exim_sha_update_string(h, openssl_options); +exim_sha_update_string(h, ob->tls_require_ciphers); +exim_sha_update_string(h, tlsp->sni); +# ifdef EXIM_HAVE_ALPN +exim_sha_update_string(h, ob->tls_alpn); +# endif +exim_sha_finish(h, &b); +for (g = string_get(b.len*2+1); b.len-- > 0; ) + g = string_fmt_append(g, "%02x", *b.data++); +tlsp->resume_index = string_from_gstring(g); +DEBUG(D_tls) debug_printf("TLS: resume session index %s\n", tlsp->resume_index); +#endif +} + #endif /*!DISABLE_TLS*/ #endif /*!MACRO_PREDEF*/