-/* $Cambridge: exim/src/src/smtp_in.c,v 1.55 2007/02/20 15:58:02 ph10 Exp $ */
-
/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2007 */
+/* Copyright (c) University of Cambridge 1995 - 2009 */
/* See the file NOTICE for conditions of use and distribution. */
/* Functions for handling an incoming SMTP call. */
int allow_severity = LOG_INFO;
int deny_severity = LOG_NOTICE;
+uschar *tcp_wrappers_name;
#endif
/* Size of buffer for reading SMTP commands. We used to use 512, as defined
by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
commands that accept arguments, and this in particular applies to AUTH, where
-the data can be quite long. */
+the data can be quite long. More recently this value was 2048 in Exim;
+however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
+such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
+The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
+we need room to handle large base64-encoded AUTHs for GSSAPI.
+*/
-#define smtp_cmd_buffer_size 2048
+#define smtp_cmd_buffer_size 16384
/* Size of buffer for reading SMTP incoming packets */
/* Structure for SMTP command list */
typedef struct {
- char *name;
+ const char *name;
int len;
short int cmd;
short int has_arg;
static BOOL helo_accept_junk;
static BOOL count_nonmail;
static BOOL pipelining_advertised;
+static BOOL rcpt_smtp_response_same;
+static BOOL rcpt_in_progress;
static int nonmail_command_count;
+static BOOL smtp_exit_function_called = 0;
static int synprot_error_count;
static int unknown_command_count;
static int sync_cmd_limit;
static int smtp_write_error = 0;
+static uschar *rcpt_smtp_response;
static uschar *smtp_data_buffer;
static uschar *smtp_cmd_data;
else smtp_had_eof = 1;
return EOF;
}
+#ifndef DISABLE_DKIM
+ dkim_exim_verify_feed(smtp_inbuffer, rc);
+#endif
smtp_inend = smtp_inbuffer + rc;
smtp_inptr = smtp_inbuffer;
}
+/*************************************************
+* Test for characters in the SMTP buffer *
+*************************************************/
+
+/* Used at the end of a message
+
+Arguments: none
+Returns: TRUE/FALSE
+*/
+
+BOOL
+smtp_buffered(void)
+{
+return smtp_inptr < smtp_inend;
+}
+
+
/*************************************************
* Write formatted string to SMTP channel *
*/
void
-smtp_printf(char *format, ...)
+smtp_printf(const char *format, ...)
{
va_list ap;
+va_start(ap, format);
+smtp_vprintf(format, ap);
+va_end(ap);
+}
+
+/* This is split off so that verify.c:respond_printf() can, in effect, call
+smtp_printf(), bearing in mind that in C a vararg function can't directly
+call another vararg function, only a function which accepts a va_list. */
+
+void
+smtp_vprintf(const char *format, va_list ap)
+{
+BOOL yield;
+
+yield = string_vformat(big_buffer, big_buffer_size, format, ap);
+
DEBUG(D_receive)
{
- uschar *cr, *end;
- va_start(ap, format);
- (void) string_vformat(big_buffer, big_buffer_size, format, ap);
- va_end(ap);
- end = big_buffer + Ustrlen(big_buffer);
- while ((cr = Ustrchr(big_buffer, '\r')) != NULL) /* lose CRs */
- memmove(cr, cr + 1, (end--) - cr);
- debug_printf("SMTP>> %s", big_buffer);
+ void *reset_point = store_get(0);
+ uschar *msg_copy, *cr, *end;
+ msg_copy = string_copy(big_buffer);
+ end = msg_copy + Ustrlen(msg_copy);
+ while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
+ memmove(cr, cr + 1, (end--) - cr);
+ debug_printf("SMTP>> %s", msg_copy);
+ store_reset(reset_point);
}
-va_start(ap, format);
+if (!yield)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
+ smtp_closedown(US"Unexpected error");
+ exim_exit(EXIT_FAILURE);
+ }
-/* If in a TLS session we have to format the string, and then write it using a
-TLS function. */
+/* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
+have had the same. Note: this code is also present in smtp_respond(). It would
+be tidier to have it only in one place, but when it was added, it was easier to
+do it that way, so as not to have to mess with the code for the RCPT command,
+which sometimes uses smtp_printf() and sometimes smtp_respond(). */
+
+if (rcpt_in_progress)
+ {
+ if (rcpt_smtp_response == NULL)
+ rcpt_smtp_response = string_copy(big_buffer);
+ else if (rcpt_smtp_response_same &&
+ Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
+ rcpt_smtp_response_same = FALSE;
+ rcpt_in_progress = FALSE;
+ }
+
+/* Now write the string */
#ifdef SUPPORT_TLS
if (tls_active >= 0)
{
- if (!string_vformat(big_buffer, big_buffer_size, format, ap))
- {
- log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf");
- smtp_closedown(US"Unexpected error");
- exim_exit(EXIT_FAILURE);
- }
if (tls_write(big_buffer, Ustrlen(big_buffer)) < 0) smtp_write_error = -1;
}
else
#endif
-/* Otherwise, just use the standard library function. */
-
-if (vfprintf(smtp_out, format, ap) < 0) smtp_write_error = -1;
-va_end(ap);
+if (fprintf(smtp_out, "%s", big_buffer) < 0) smtp_write_error = -1;
}
host_and_ident(FALSE));
if (smtp_batched_input)
moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
-smtp_printf("421 %s: SMTP command timeout - closing connection\r\n",
- smtp_active_hostname);
-mac_smtp_fflush();
+smtp_notquit_exit(US"command-timeout", US"421",
+ US"%s: SMTP command timeout - closing connection", smtp_active_hostname);
exim_exit(EXIT_FAILURE);
}
log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
if (smtp_batched_input)
moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
-smtp_printf("421 %s: Service not available - closing connection\r\n",
- smtp_active_hostname);
+smtp_notquit_exit(US"signal-exit", US"421",
+ US"%s: Service not available - closing connection", smtp_active_hostname);
exim_exit(EXIT_FAILURE);
}
except QUIT. The existence of an SMTP call is detected by the non-NULLness of
smtp_in.
-Argument: SMTP reply string to send, excluding the code
+Arguments:
+ message SMTP reply string to send, excluding the code
+
Returns: nothing
*/
s = string_append(s, &size, &ptr, 2, US" CV=",
tls_certificate_verified? "yes":"no");
if ((log_extra_selector & LX_tls_peerdn) != 0 && tls_peerdn != NULL)
- s = string_append(s, &size, &ptr, 3, US" DN=\"", tls_peerdn, US"\"");
+ s = string_append(s, &size, &ptr, 3, US" DN=\"",
+ string_printing(tls_peerdn), US"\"");
#endif
sep = (smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE)?
message_size = -1;
acl_added_headers = NULL;
queue_only_policy = FALSE;
+rcpt_smtp_response = NULL;
+rcpt_smtp_response_same = TRUE;
+rcpt_in_progress = FALSE;
deliver_freeze = FALSE; /* Can be set by ACL */
freeze_tell = freeze_tell_config; /* Can be set by ACL */
fake_response = OK; /* Can be set by ACL */
bmi_run = 0;
bmi_verdicts = NULL;
#endif
-#ifdef EXPERIMENTAL_DOMAINKEYS
-dk_do_verify = 0;
+#ifndef DISABLE_DKIM
+dkim_signers = NULL;
+dkim_disable_verify = FALSE;
+dkim_collect_input = FALSE;
#endif
#ifdef EXPERIMENTAL_SPF
spf_header_comment = NULL;
pipelining_advertised = FALSE;
pipelining_enable = TRUE;
sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
+smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
memset(sender_host_cache, 0, sizeof(sender_host_cache));
receive_ungetc = smtp_ungetc;
receive_feof = smtp_feof;
receive_ferror = smtp_ferror;
+receive_smtp_buffered = smtp_buffered;
smtp_inptr = smtp_inend = smtp_inbuffer;
smtp_had_eof = smtp_had_error = 0;
#ifdef USE_TCP_WRAPPERS
errno = 0;
- if (!hosts_ctl("exim",
+ tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name);
+ if (tcp_wrappers_name == NULL)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
+ "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
+ expand_string_message);
+ }
+ if (!hosts_ctl(tcp_wrappers_name,
(sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
(sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
(sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
esclen = codelen - 4;
}
+/* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
+have had the same. Note: this code is also present in smtp_printf(). It would
+be tidier to have it only in one place, but when it was added, it was easier to
+do it that way, so as not to have to mess with the code for the RCPT command,
+which sometimes uses smtp_printf() and sometimes smtp_respond(). */
+
+if (rcpt_in_progress)
+ {
+ if (rcpt_smtp_response == NULL)
+ rcpt_smtp_response = string_copy(msg);
+ else if (rcpt_smtp_response_same &&
+ Ustrcmp(rcpt_smtp_response, msg) != 0)
+ rcpt_smtp_response_same = FALSE;
+ rcpt_in_progress = FALSE;
+ }
+
+/* Not output the message, splitting it up into multiple lines if necessary. */
+
for (;;)
{
uschar *nl = Ustrchr(msg, '\n');
if (sender_verified_failed != NULL &&
!testflag(sender_verified_failed, af_sverify_told))
{
+ BOOL save_rcpt_in_progress = rcpt_in_progress;
+ rcpt_in_progress = FALSE; /* So as not to treat these as the error */
+
setflag(sender_verified_failed, af_sverify_told);
if (rc != FAIL || (log_extra_selector & LX_sender_verify_fail) != 0)
"Verification failed for <%s>\n%s",
sender_verified_failed->address,
sender_verified_failed->user_message));
+
+ rcpt_in_progress = save_rcpt_in_progress;
}
/* Sort out text for logging */
log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
smtp_get_connection_info());
+
+/* Run the not-quit ACL, but without any custom messages. This should not be a
+problem, because we get here only if some other ACL has issued "drop", and
+in that case, *its* custom messages will have been used above. */
+
+smtp_notquit_exit(US"acl-drop", NULL, NULL);
return 2;
}
+/*************************************************
+* Handle SMTP exit when QUIT is not given *
+*************************************************/
+
+/* This function provides a logging/statistics hook for when an SMTP connection
+is dropped on the floor or the other end goes away. It's a global function
+because it's called from receive.c as well as this module. As well as running
+the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
+response, either with a custom message from the ACL, or using a default. There
+is one case, however, when no message is output - after "drop". In that case,
+the ACL that obeyed "drop" has already supplied the custom message, and NULL is
+passed to this function.
+
+In case things go wrong while processing this function, causing an error that
+may re-enter this funtion, there is a recursion check.
+
+Arguments:
+ reason What $smtp_notquit_reason will be set to in the ACL;
+ if NULL, the ACL is not run
+ code The error code to return as part of the response
+ defaultrespond The default message if there's no user_msg
+
+Returns: Nothing
+*/
+
+void
+smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
+{
+int rc;
+uschar *user_msg = NULL;
+uschar *log_msg = NULL;
+
+/* Check for recursive acll */
+
+if (smtp_exit_function_called)
+ {
+ log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
+ reason);
+ return;
+ }
+smtp_exit_function_called = TRUE;
+
+/* Call the not-QUIT ACL, if there is one, unless no reason is given. */
+
+if (acl_smtp_notquit != NULL && reason != NULL)
+ {
+ smtp_notquit_reason = reason;
+ rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
+ &log_msg);
+ if (rc == ERROR)
+ log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
+ log_msg);
+ }
+
+/* Write an SMTP response if we are expected to give one. As the default
+responses are all internal, they should always fit in the buffer, but code a
+warning, just in case. Note that string_vformat() still leaves a complete
+string, even if it is incomplete. */
+
+if (code != NULL && defaultrespond != NULL)
+ {
+ if (user_msg == NULL)
+ {
+ uschar buffer[128];
+ va_list ap;
+ va_start(ap, defaultrespond);
+ if (!string_vformat(buffer, sizeof(buffer), CS defaultrespond, ap))
+ log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_notquit_exit()");
+ smtp_printf("%s %s\r\n", code, buffer);
+ va_end(ap);
+ }
+ else
+ smtp_respond(code, 3, TRUE, user_msg);
+ mac_smtp_fflush();
+ }
+}
+
+
+
+
/*************************************************
* Verify HELO argument *
*************************************************/
in order to be able to log the sender address on failure. */
if (strcmpic(name, US"SIZE") == 0 &&
- ((size = (int)Ustrtoul(value, &end, 10)), *end == 0))
+ ((size = Ustrtoul(value, &end, 10)), *end == 0))
{
if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
size = INT_MAX;
break;
- /* The RCPT command requires an address as an operand. All we do
- here is to parse it for syntactic correctness. There may be any number
- of RCPT commands, specifying multiple senders. We build them all into
- a data structure that is in argc/argv format. The start/end values
- given by parse_extract_address are not used, as we keep only the
- extracted address. */
+ /* The RCPT command requires an address as an operand. There may be any
+ number of RCPT commands, specifying multiple recipients. We build them all
+ into a data structure. The start/end values given by parse_extract_address
+ are not used, as we keep only the extracted address. */
case RCPT_CMD:
HAD(SCH_RCPT);
rcpt_count++;
- was_rcpt = TRUE;
+ was_rcpt = rcpt_in_progress = TRUE;
/* There must be a sender address; if the sender was rejected and
pipelining was advertised, we assume the client was pipelining, and do not
DATA command.
The example in the pipelining RFC 2920 uses 554, but I use 503 here
- because it is the same whether pipelining is in use or not. */
+ because it is the same whether pipelining is in use or not.
+
+ If all the RCPT commands that precede DATA provoked the same error message
+ (often indicating some kind of system error), it is helpful to include it
+ with the DATA rejection (an idea suggested by Tony Finch). */
case DATA_CMD:
HAD(SCH_DATA);
if (!discarded && recipients_count <= 0)
{
+ if (rcpt_smtp_response_same && rcpt_smtp_response != NULL)
+ {
+ uschar *code = US"503";
+ int len = Ustrlen(rcpt_smtp_response);
+ smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
+ "this error:");
+ /* Responses from smtp_printf() will have \r\n on the end */
+ if (len > 2 && rcpt_smtp_response[len-2] == '\r')
+ rcpt_smtp_response[len-2] = 0;
+ smtp_respond(code, 3, FALSE, rcpt_smtp_response);
+ }
if (pipelining_advertised && last_was_rcpt)
- smtp_printf("503 valid RCPT command must precede DATA\r\n");
+ smtp_printf("503 Valid RCPT command must precede DATA\r\n");
else
done = synprot_error(L_smtp_protocol_error, 503, NULL,
US"valid RCPT command must precede DATA");
toomany = FALSE;
cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
+ /* There's an attack where more data is read in past the STARTTLS command
+ before TLS is negotiated, then assumed to be part of the secure session
+ when used afterwards; we use segregated input buffers, so are not
+ vulnerable, but we want to note when it happens and, for sheer paranoia,
+ ensure that the buffer is "wiped".
+ Pipelining sync checks will normally have protected us too, unless disabled
+ by configuration. */
+
+ if (receive_smtp_buffered())
+ {
+ DEBUG(D_any)
+ debug_printf("Non-empty input buffer after STARTTLS; naive attack?");
+ if (tls_active < 0)
+ smtp_inend = smtp_inptr = smtp_inbuffer;
+ /* and if TLS is already active, tls_server_start() should fail */
+ }
+
+ /* There is nothing we value in the input buffer and if TLS is succesfully
+ negotiated, we won't use this buffer again; if TLS fails, we'll just read
+ fresh content into it. The buffer contains arbitrary content from an
+ untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
+ It seems safest to just wipe away the content rather than leave it as a
+ target to jump to. */
+
+ memset(smtp_inbuffer, 0, in_buffer_size);
+
/* Attempt to start up a TLS session, and if successful, discard all
knowledge that was obtained previously. At least, that's what the RFC says,
and that's what happens by default. However, in order to work round YAEB,
case EOF_CMD:
log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
smtp_get_connection_info());
+ smtp_notquit_exit(US"tls-failed", NULL, NULL);
done = 2;
break;
+ /* It is perhaps arguable as to which exit ACL should be called here,
+ but as it is probably a situtation that almost never arises, it
+ probably doesn't matter. We choose to call the real QUIT ACL, which in
+ some sense is perhaps "right". */
+
case QUIT_CMD:
- smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
+ user_msg = NULL;
+ if (acl_smtp_quit != NULL)
+ {
+ rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
+ &log_msg);
+ if (rc == ERROR)
+ log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
+ log_msg);
+ }
+ if (user_msg == NULL)
+ smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
+ else
+ smtp_respond(US"221", 3, TRUE, user_msg);
log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
smtp_get_connection_info());
done = 2;
case QUIT_CMD:
HAD(SCH_QUIT);
incomplete_transaction_log(US"QUIT");
-
if (acl_smtp_quit != NULL)
{
- rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit,&user_msg,&log_msg);
+ rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg, &log_msg);
if (rc == ERROR)
log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
log_msg);
}
-
if (user_msg == NULL)
smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
else
break;
- /* Show ETRN/EXPN/VRFY if there's
- an ACL for checking hosts; if actually used, a check will be done for
- permitted hosts. */
+ /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
+ used, a check will be done for permitted hosts. Show STARTTLS only if not
+ already in a TLS session and if it would be advertised in the EHLO
+ response. */
case HELP_CMD:
HAD(SCH_HELP);
buffer[0] = 0;
Ustrcat(buffer, " AUTH");
#ifdef SUPPORT_TLS
- Ustrcat(buffer, " STARTTLS");
+ if (tls_active < 0 &&
+ verify_check_host(&tls_advertise_hosts) != FAIL)
+ Ustrcat(buffer, " STARTTLS");
#endif
Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
Ustrcat(buffer, " NOOP QUIT RSET HELP");
case EOF_CMD:
incomplete_transaction_log(US"connection lost");
- smtp_printf("421 %s lost input connection\r\n", smtp_active_hostname);
+ smtp_notquit_exit(US"connection-lost", US"421",
+ US"%s lost input connection", smtp_active_hostname);
/* Don't log by default unless in the middle of a message, as some mailers
just drop the call rather than sending QUIT, and it clutters up the logs.
pipelining_advertised? "" : " not",
smtp_cmd_buffer, host_and_ident(TRUE),
string_printing(smtp_inptr));
- smtp_printf("554 SMTP synchronization error\r\n");
+ smtp_notquit_exit(US"synchronization-error", US"554",
+ US"SMTP synchronization error");
done = 1; /* Pretend eof - drops connection */
break;
log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
"nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
s - smtp_cmd_buffer, smtp_cmd_buffer);
- smtp_printf("554 Too many nonmail commands\r\n");
+ smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
done = 1; /* Pretend eof - drops connection */
break;
string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
US"unrecognized command");
incomplete_transaction_log(US"unrecognized command");
- smtp_printf("500 Too many unrecognized commands\r\n");
+ smtp_notquit_exit(US"bad-commands", US"500",
+ US"Too many unrecognized commands");
done = 2;
log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
"unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
projects / exim.git / blobdiff