X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/b536a578fbabdc9d39da53d54a8d7700ba537431..e4e3d18dad8b9b8560889f552e1060d0f83c7159:/src/src/smtp_out.c diff --git a/src/src/smtp_out.c b/src/src/smtp_out.c index c5eafbc57..eae74da00 100644 --- a/src/src/smtp_out.c +++ b/src/src/smtp_out.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. */ /* A number of functions for driving outgoing SMTP calls. */ @@ -52,9 +53,21 @@ if (!(expint = expand_string(istring))) return FALSE; } -while (isspace(*expint)) expint++; -if (*expint == 0) return TRUE; +if (is_tainted(expint)) + { + log_write(0, LOG_MAIN|LOG_PANIC, + "attempt to use tainted value '%s' from '%s' for interface", + expint, istring); + addr->transport_return = PANIC; + addr->message = string_sprintf("failed to expand \"interface\" " + "option for %s: configuration error", msg); + return FALSE; + } + +Uskip_whitespace(&expint); +if (!*expint) return TRUE; +/* we just tested to ensure no taint, so big_buffer is ok */ while ((iface = string_nextinlist(&expint, &sep, big_buffer, big_buffer_size))) { @@ -144,58 +157,107 @@ return TRUE; static void tfo_out_check(int sock) { -# if defined(TCP_INFO) && defined(EXIM_HAVE_TCPI_UNACKED) +# ifdef __FreeBSD__ struct tcp_info tinfo; socklen_t len = sizeof(tinfo); -if (getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0) - switch (tcp_out_fastopen) - { - /* This is a somewhat dubious detection method; totally undocumented so likely - to fail in future kernels. There seems to be no documented way. What we really - want to know is if the server sent smtp-banner data before our ACK of his SYN,ACK - hit him. What this (possibly?) detects is whether we sent a TFO cookie with our - SYN, as distinct from a TFO request. This gets a false-positive when the server - key is rotated; we send the old one (which this test sees) but the server returns - the new one and does not send its SMTP banner before we ACK his SYN,ACK. - To force that rotation case: - '# echo -n "00000000-00000000-00000000-0000000" >/proc/sys/net/ipv4/tcp_fastopen_key' - The kernel seems to be counting unack'd packets. */ - - case TFO_ATTEMPTED: - if (tinfo.tcpi_unacked > 1) - { - DEBUG(D_transport|D_v) - debug_printf("TCP_FASTOPEN tcpi_unacked %d\n", tinfo.tcpi_unacked); - tcp_out_fastopen = TFO_USED; - } - break; +/* A getsockopt TCP_FASTOPEN unfortunately returns "was-used" for a TFO/R as +well as a TFO/C. Use what we can of the Linux hack below; reliability issues ditto. */ +switch (tcp_out_fastopen) + { + case TFO_ATTEMPTED_NODATA: + if ( getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0 + && tinfo.tcpi_state == TCPS_SYN_SENT + && tinfo.__tcpi_unacked > 0 + ) + { + DEBUG(D_transport|D_v) + debug_printf("TCP_FASTOPEN tcpi_unacked %d\n", tinfo.__tcpi_unacked); + tcp_out_fastopen = TFO_USED_NODATA; + } + break; + /* + case TFO_ATTEMPTED_DATA: + case TFO_ATTEMPTED_DATA: + if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA) XXX no equvalent as of 12.2 + */ + } -# ifdef notdef /* This seems to always fire, meaning that we cannot tell - whether the server accepted data we sent. For now assume - that it did. */ +switch (tcp_out_fastopen) + { + case TFO_ATTEMPTED_DATA: tcp_out_fastopen = TFO_USED_DATA; break; + default: break; /* compiler quietening */ + } - /* If there was data-on-SYN but we had to retrasnmit it, declare no TFO */ +# else /* Linux & Apple */ +# if defined(TCP_INFO) && defined(EXIM_HAVE_TCPI_UNACKED) +struct tcp_info tinfo; +socklen_t len = sizeof(tinfo); + +switch (tcp_out_fastopen) + { + /* This is a somewhat dubious detection method; totally undocumented so likely + to fail in future kernels. There seems to be no documented way. What we really + want to know is if the server sent smtp-banner data before our ACK of his SYN,ACK + hit him. What this (possibly?) detects is whether we sent a TFO cookie with our + SYN, as distinct from a TFO request. This gets a false-positive when the server + key is rotated; we send the old one (which this test sees) but the server returns + the new one and does not send its SMTP banner before we ACK his SYN,ACK. + To force that rotation case: + '# echo -n "00000000-00000000-00000000-0000000" >/proc/sys/net/ipv4/tcp_fastopen_key' + The kernel seems to be counting unack'd packets. */ + + case TFO_ATTEMPTED_NODATA: + if ( getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0 + && tinfo.tcpi_state == TCP_SYN_SENT + && tinfo.tcpi_unacked > 1 + ) + { + DEBUG(D_transport|D_v) + debug_printf("TCP_FASTOPEN tcpi_unacked %d\n", tinfo.tcpi_unacked); + tcp_out_fastopen = TFO_USED_NODATA; + } + break; - case TFO_USED: - if (!(tinfo.tcpi_options & TCPI_OPT_SYN_DATA)) + /* When called after waiting for received data we should be able + to tell if data we sent was accepted. */ + + case TFO_ATTEMPTED_DATA: + if ( getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0 + && tinfo.tcpi_state == TCP_ESTABLISHED + ) + if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA) + { + DEBUG(D_transport|D_v) debug_printf("TFO: data was acked\n"); + tcp_out_fastopen = TFO_USED_DATA; + } + else { DEBUG(D_transport|D_v) debug_printf("TFO: had to retransmit\n"); tcp_out_fastopen = TFO_NOT_USED; } - break; + break; - default: break; /* compiler quietening */ + default: break; /* compiler quietening */ + } # endif - } -# endif +# endif /* Linux & Apple */ } #endif -/* Arguments as for smtp_connect(), plus - early_data if non-NULL, idenmpotent data to be sent - +/* Arguments: + host host item containing name and address and port + host_af AF_INET or AF_INET6 + port TCP port number + interface outgoing interface address or NULL + tb transport + timeout timeout value or 0 + early_data if non-NULL, idempotent data to be sent - preferably in the TCP SYN segment + Special case: non-NULL but with NULL blob.data - caller is + client-data-first (eg. TLS-on-connect) and a lazy-TCP-connect is + acceptable. Returns: connected socket number, or -1 with errno set */ @@ -259,20 +321,51 @@ if (interface && ip_bind(sock, host_af, interface, 0) < 0) /* Connect to the remote host, and add keepalive to the socket before returning it, if requested. If the build supports TFO, request it - and if the caller -requested some early-data then include that in the TFO request. */ +requested some early-data then include that in the TFO request. If there is +early-data but no TFO support, send it after connecting. */ else { #ifdef TCP_FASTOPEN + /* See if TCP Fast Open usable. Default is a traditional 3WHS connect */ if (verify_check_given_host(CUSS &ob->hosts_try_fastopen, host) == OK) - fastopen_blob = early_data ? early_data : &tcp_fastopen_nodata; + { + if (!early_data) + fastopen_blob = &tcp_fastopen_nodata; /* TFO, with no data */ + else if (early_data->data) + fastopen_blob = early_data; /* TFO, with data */ +# ifdef TCP_FASTOPEN_CONNECT + else + { /* expecting client data */ + debug_printf(" set up lazy-connect\n"); + setsockopt(sock, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, US &on, sizeof(on)); + /* fastopen_blob = NULL; lazy TFO, triggered by data write */ + } +# endif + } #endif if (ip_connect(sock, host_af, host->address, port, timeout, fastopen_blob) < 0) save_errno = errno; else if (early_data && !fastopen_blob && early_data->data && early_data->len) + { + /* We had some early-data to send, but couldn't do TFO */ + HDEBUG(D_transport|D_acl|D_v) + debug_printf("sending %ld nonTFO early-data\n", (long)early_data->len); + +#ifdef TCP_QUICKACK_notdef + (void) setsockopt(sock, IPPROTO_TCP, TCP_QUICKACK, US &off, sizeof(off)); +#endif if (send(sock, early_data->data, early_data->len, 0) < 0) save_errno = errno; + } +#ifdef TCP_QUICKACK_notdef + /* Under TFO (with openssl & pipe-conn; testcase 4069, as of + 5.10.8-100.fc32.x86_64) this seems to be inop. + Perhaps overwritten when we (client) go -> ESTABLISHED on seeing the 3rd-ACK? + For that case, added at smtp_reap_banner(). */ + (void) setsockopt(sock, IPPROTO_TCP, TCP_QUICKACK, US &off, sizeof(off)); +#endif } /* Either bind() or connect() failed */ @@ -281,7 +374,7 @@ if (save_errno != 0) { HDEBUG(D_transport|D_acl|D_v) { - debug_printf_indent("failed: %s", CUstrerror(save_errno)); + debug_printf_indent(" failed: %s", CUstrerror(save_errno)); if (save_errno == ETIMEDOUT) debug_printf(" (timeout=%s)", readconf_printtime(timeout)); debug_printf("\n"); @@ -291,13 +384,14 @@ if (save_errno != 0) return -1; } -/* Both bind() and connect() succeeded */ +/* Both bind() and connect() succeeded, and any early-data */ else { union sockaddr_46 interface_sock; EXIM_SOCKLEN_T size = sizeof(interface_sock); - HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("connected\n"); + + HDEBUG(D_transport|D_acl|D_v) debug_printf_indent(" connected\n"); if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0) sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port); else @@ -307,9 +401,10 @@ else close(sock); return -1; } + if (ob->keepalive) ip_keepalive(sock, host->address, TRUE); #ifdef TCP_FASTOPEN - if (fastopen_blob) tfo_out_check(sock); + tfo_out_check(sock); #endif return sock; } @@ -324,7 +419,7 @@ smtp_port_for_connect(host_item * host, int port) { if (host->port != PORT_NONE) { - HDEBUG(D_transport|D_acl|D_v) + HDEBUG(D_transport|D_acl|D_v) if (port != host->port) debug_printf_indent("Transport port=%d replaced by host-specific port=%d\n", port, host->port); port = host->port; @@ -343,45 +438,65 @@ non-IPv6 systems, to enable the code to be less messy. However, on such systems host->address will always be an IPv4 address. Arguments: - host host item containing name and address and port - host_af AF_INET or AF_INET6 - interface outgoing interface address or NULL - timeout timeout value or 0 - tb transport + sc details for making connection: host, af, interface, transport + early_data if non-NULL, data to be sent - preferably in the TCP SYN segment + Special case: non-NULL but with NULL blob.data - caller is + client-data-first (eg. TLS-on-connect) and a lazy-TCP-connect is + acceptable. Returns: connected socket number, or -1 with errno set */ int -smtp_connect(host_item *host, int host_af, uschar *interface, - int timeout, transport_instance * tb) +smtp_connect(smtp_connect_args * sc, const blob * early_data) { -int port = host->port; -#ifdef SUPPORT_SOCKS -smtp_transport_options_block * ob = - (smtp_transport_options_block *)tb->options_block; -#endif +int port = sc->host->port; +smtp_transport_options_block * ob = sc->ob; -callout_address = string_sprintf("[%s]:%d", host->address, port); +callout_address = string_sprintf("[%s]:%d", sc->host->address, port); HDEBUG(D_transport|D_acl|D_v) { uschar * s = US" "; - if (interface) s = string_sprintf(" from %s ", interface); + if (sc->interface) s = string_sprintf(" from %s ", sc->interface); #ifdef SUPPORT_SOCKS if (ob->socks_proxy) s = string_sprintf("%svia proxy ", s); #endif - debug_printf_indent("Connecting to %s %s%s... ", host->name, callout_address, s); + debug_printf_indent("Connecting to %s %s%s... ", sc->host->name, callout_address, s); } /* Create and connect the socket */ #ifdef SUPPORT_SOCKS if (ob->socks_proxy) - return socks_sock_connect(host, host_af, port, interface, tb, timeout); + { + int sock = socks_sock_connect(sc->host, sc->host_af, port, sc->interface, + sc->tblock, ob->connect_timeout); + + if (sock >= 0) + { + if (early_data && early_data->data && early_data->len) + if (send(sock, early_data->data, early_data->len, 0) < 0) + { + int save_errno = errno; + HDEBUG(D_transport|D_acl|D_v) + { + debug_printf_indent("failed: %s", CUstrerror(save_errno)); + if (save_errno == ETIMEDOUT) + debug_printf(" (timeout=%s)", readconf_printtime(ob->connect_timeout)); + debug_printf("\n"); + } + (void)close(sock); + sock = -1; + errno = save_errno; + } + } + return sock; + } #endif -return smtp_sock_connect(host, host_af, port, interface, tb, timeout, NULL); +return smtp_sock_connect(sc->host, sc->host_af, port, sc->interface, + sc->tblock, ob->connect_timeout, early_data); } @@ -410,18 +525,49 @@ BOOL more = mode == SCMD_MORE; HDEBUG(D_transport|D_acl) debug_printf_indent("cmd buf flush %d bytes%s\n", n, more ? " (more expected)" : ""); -#ifdef SUPPORT_TLS +#ifndef DISABLE_TLS if (outblock->cctx->tls_ctx) rc = tls_write(outblock->cctx->tls_ctx, outblock->buffer, n, more); else #endif - rc = send(outblock->cctx->sock, outblock->buffer, n, + + { + if (outblock->conn_args) + { + blob early_data = { .data = outblock->buffer, .len = n }; + + /* We ignore the more-flag if we're doing a connect with early-data, which + means we won't get BDAT+data. A pity, but wise due to the idempotency + requirement: TFO with data can, in rare cases, replay the data to the + receiver. */ + + if ( (outblock->cctx->sock = smtp_connect(outblock->conn_args, &early_data)) + < 0) + return FALSE; + outblock->conn_args = NULL; + rc = n; + } + else + { + rc = send(outblock->cctx->sock, outblock->buffer, n, #ifdef MSG_MORE - more ? MSG_MORE : 0 + more ? MSG_MORE : 0 #else - 0 + 0 #endif - ); + ); + +#if defined(__linux__) + /* This is a workaround for a current linux kernel bug: as of + 5.6.8-200.fc31.x86_64 small (cctx->sock, IPPROTO_TCP, TCP_CORK, &off, sizeof(off)); +#endif + } + } if (rc <= 0) { @@ -460,34 +606,40 @@ int smtp_write_command(void * sx, int mode, const char *format, ...) { smtp_outblock * outblock = &((smtp_context *)sx)->outblock; -int count; int rc = 0; -va_list ap; if (format) { + gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer }; + va_list ap; + + /* Use taint-unchecked routines for writing into big_buffer, trusting that + we'll never expand the results. Actually, the error-message use - leaving + the results in big_buffer for potential later use - is uncomfortably distant. + XXX Would be better to assume all smtp commands are short, use normal pool + alloc rather than big_buffer, and another global for the data-for-error. */ + va_start(ap, format); - if (!string_vformat(big_buffer, big_buffer_size, CS format, ap)) + if (!string_vformat(&gs, SVFMT_TAINT_NOCHK, CS format, ap)) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing " "SMTP"); va_end(ap); - count = Ustrlen(big_buffer); + string_from_gstring(&gs); - if (count > outblock->buffersize) + if (gs.ptr > outblock->buffersize) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing " "SMTP"); - if (count > outblock->buffersize - (outblock->ptr - outblock->buffer)) + if (gs.ptr > outblock->buffersize - (outblock->ptr - outblock->buffer)) { rc = outblock->cmd_count; /* flush resets */ if (!flush_buffer(outblock, SCMD_FLUSH)) return -1; } - Ustrncpy(CS outblock->ptr, big_buffer, count); - outblock->ptr += count; + Ustrncpy(outblock->ptr, gs.s, gs.ptr); + outblock->ptr += gs.ptr; outblock->cmd_count++; - count -= 2; - big_buffer[count] = 0; /* remove \r\n for error message */ + gs.ptr -= 2; string_from_gstring(&gs); /* remove \r\n for error message */ /* We want to hide the actual data sent in AUTH transactions from reflections and logs. While authenticating, a flag is set in the outblock to enable this. @@ -504,10 +656,12 @@ if (format) while (!isspace(*p)) p++; while (isspace(*p)) p++; } - while (*p != 0) *p++ = '*'; + while (*p) *p++ = '*'; } - HDEBUG(D_transport|D_acl|D_v) debug_printf_indent(" SMTP>> %s\n", big_buffer); + HDEBUG(D_transport|D_acl|D_v) debug_printf_indent(" SMTP%c> %s\n", + mode == SCMD_BUFFER ? '|' : mode == SCMD_MORE ? '+' : '>', + big_buffer); } if (mode != SCMD_BUFFER) @@ -535,14 +689,14 @@ Arguments: inblock the SMTP input block (contains holding buffer, socket, etc.) buffer where to put the line size space available for the line - timeout the timeout to use when reading a packet + timelimit deadline for reading the lime, seconds past epoch Returns: length of a line that has been put in the buffer - -1 otherwise, with errno set + -1 otherwise, with errno set, and inblock->ptr adjusted */ static int -read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout) +read_response_line(smtp_inblock *inblock, uschar *buffer, int size, time_t timelimit) { uschar *p = buffer; uschar *ptr = inblock->ptr; @@ -579,15 +733,16 @@ for (;;) { *p = 0; /* Leave malformed line for error message */ errno = ERRNO_SMTPFORMAT; + inblock->ptr = ptr; return -1; } } /* Need to read a new input packet. */ - if((rc = ip_recv(cctx, inblock->buffer, inblock->buffersize, timeout)) <= 0) + if((rc = ip_recv(cctx, inblock->buffer, inblock->buffersize, timelimit)) <= 0) { - DEBUG(D_deliver|D_transport|D_acl) + DEBUG(D_deliver|D_transport|D_acl|D_v) debug_printf_indent(errno ? " SMTP(%s)<<\n" : " SMTP(closed)<<\n", strerror(errno)); break; @@ -633,27 +788,43 @@ Arguments: Returns: TRUE if a valid, non-error response was received; else FALSE */ +/*XXX could move to smtp transport; no other users */ BOOL -smtp_read_response(void * sx, uschar *buffer, int size, int okdigit, +smtp_read_response(void * sx0, uschar * buffer, int size, int okdigit, int timeout) { -smtp_inblock * inblock = &((smtp_context *)sx)->inblock; -uschar *ptr = buffer; -int count; +smtp_context * sx = sx0; +uschar * ptr = buffer; +int count = 0; +time_t timelimit = time(NULL) + timeout; errno = 0; /* Ensure errno starts out zero */ +#ifndef DISABLE_PIPE_CONNECT +if (sx->pending_BANNER || sx->pending_EHLO) + { + int rc; + if ((rc = smtp_reap_early_pipe(sx, &count)) != OK) + { + DEBUG(D_transport) debug_printf("failed reaping pipelined cmd responsess\n"); + buffer[0] = '\0'; + if (rc == DEFER) errno = ERRNO_TLSFAILURE; + return FALSE; + } + } +#endif + /* This is a loop to read and concatenate the lines that make up a multi-line response. */ for (;;) { - if ((count = read_response_line(inblock, ptr, size, timeout)) < 0) + if ((count = read_response_line(&sx->inblock, ptr, size, timelimit)) < 0) return FALSE; HDEBUG(D_transport|D_acl|D_v) - debug_printf_indent(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr); + debug_printf_indent(" %s %s\n", ptr == buffer ? "SMTP<<" : " ", ptr); /* Check the format of the response: it must start with three digits; if these are followed by a space or end of line, the response is complete. If @@ -687,6 +858,10 @@ for (;;) size -= count + 1; } +#ifdef TCP_FASTOPEN + tfo_out_check(sx->cctx.sock); +#endif + /* Return a value that depends on the SMTP return code. On some systems a non-zero value of errno has been seen at this point, so ensure it is zero, because the caller of this function looks at errno when FALSE is returned, to