-/* $Cambridge: exim/src/src/smtp_in.c,v 1.65 2009/10/15 08:06:23 tom 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;
*/
void
-smtp_printf(char *format, ...)
+smtp_printf(const char *format, ...)
{
va_list 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.
-
-Note also that repeated calls to va_start()/va_end() pairs is claimed to be
-non-portable; meanwhile, va_copy() is also non-portable in that it's C99, so
-we end up needing OS support to define it for us. */
+call another vararg function, only a function which accepts a va_list. */
void
-smtp_vprintf(char *format, va_list ap)
+smtp_vprintf(const char *format, va_list ap)
{
-va_list ap_d;
+BOOL yield;
+
+yield = string_vformat(big_buffer, big_buffer_size, format, ap);
DEBUG(D_receive)
{
- uschar *cr, *end;
- va_copy(ap_d, ap);
- (void) string_vformat(big_buffer, big_buffer_size, format, ap_d);
- 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);
}
-if (!string_vformat(big_buffer, big_buffer_size, format, ap))
+if (!yield)
{
log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
smtp_closedown(US"Unexpected error");
#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))
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,
git://git.exim.org / exim.git / blobdiff