-/* $Cambridge: exim/src/src/acl.c,v 1.26 2005/03/29 10:56:48 ph10 Exp $ */
+/* $Cambridge: exim/src/src/acl.c,v 1.32 2005/05/17 15:00:04 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
{ US"submission", CONTROL_SUBMISSION, TRUE}
};
+/* Support data structures for Client SMTP Authorization. acl_verify_csa()
+caches its result in a tree to avoid repeated DNS queries. The result is an
+integer code which is used as an index into the following tables of
+explanatory strings and verification return codes. */
+
+static tree_node *csa_cache = NULL;
+
+enum { CSA_UNKNOWN, CSA_OK, CSA_DEFER_SRV, CSA_DEFER_ADDR,
+ CSA_FAIL_EXPLICIT, CSA_FAIL_DOMAIN, CSA_FAIL_NOADDR, CSA_FAIL_MISMATCH };
+
+/* The acl_verify_csa() return code is translated into an acl_verify() return
+code using the following table. It is OK unless the client is definitely not
+authorized. This is because CSA is supposed to be optional for sending sites,
+so recipients should not be too strict about checking it - especially because
+DNS problems are quite likely to occur. It's possible to use $csa_status in
+further ACL conditions to distinguish ok, unknown, and defer if required, but
+the aim is to make the usual configuration simple. */
+
+static int csa_return_code[] = {
+ OK, OK, OK, OK,
+ FAIL, FAIL, FAIL, FAIL
+};
+
+static uschar *csa_status_string[] = {
+ US"unknown", US"ok", US"defer", US"defer",
+ US"fail", US"fail", US"fail", US"fail"
+};
+
+static uschar *csa_reason_string[] = {
+ US"unknown",
+ US"ok",
+ US"deferred (SRV lookup failed)",
+ US"deferred (target address lookup failed)",
+ US"failed (explicit authorization required)",
+ US"failed (host name not authorized)",
+ US"failed (no authorized addresses)",
+ US"failed (client address mismatch)"
+};
+
/* Enable recursion between acl_check_internal() and acl_check_condition() */
static int acl_check_internal(int, address_item *, uschar *, int, uschar **,
s++;
}
- /* Read the name of a verb or a condition, or the start of a new ACL */
+ /* Read the name of a verb or a condition, or the start of a new ACL, which
+ can be started by a name, or by a macro definition. */
s = readconf_readname(name, sizeof(name), s);
- if (*s == ':')
- {
- if (negated || name[0] == 0)
- {
- *error = string_sprintf("malformed ACL name in \"%s\"", saveline);
- return NULL;
- }
- break;
- }
+ if (*s == ':' || isupper(name[0] && *s == '=')) return yield;
/* If a verb is unrecognized, it may be another condition or modifier that
continues the previous verb. */
strcmpic(log_message, US"sender verify failed") == 0)
text = string_sprintf("%s: %s", text, sender_verified_failed->message);
- /* Search previously logged warnings. They are kept in malloc store so they
- can be freed at the start of a new message. */
+ /* Search previously logged warnings. They are kept in malloc
+ store so they can be freed at the start of a new message. */
for (logged = acl_warn_logged; logged != NULL; logged = logged->next)
if (Ustrcmp(logged->text, text) == 0) break;
+/*************************************************
+* Check client IP address matches CSA target *
+*************************************************/
+
+/* Called from acl_verify_csa() below. This routine scans a section of a DNS
+response for address records belonging to the CSA target hostname. The section
+is specified by the reset argument, either RESET_ADDITIONAL or RESET_ANSWERS.
+If one of the addresses matches the client's IP address, then the client is
+authorized by CSA. If there are target IP addresses but none of them match
+then the client is using an unauthorized IP address. If there are no target IP
+addresses then the client cannot be using an authorized IP address. (This is
+an odd configuration - why didn't the SRV record have a weight of 1 instead?)
+
+Arguments:
+ dnsa the DNS answer block
+ dnss a DNS scan block for us to use
+ reset option specifing what portion to scan, as described above
+ target the target hostname to use for matching RR names
+
+Returns: CSA_OK successfully authorized
+ CSA_FAIL_MISMATCH addresses found but none matched
+ CSA_FAIL_NOADDR no target addresses found
+*/
+
+static int
+acl_verify_csa_address(dns_answer *dnsa, dns_scan *dnss, int reset,
+ uschar *target)
+{
+dns_record *rr;
+dns_address *da;
+
+BOOL target_found = FALSE;
+
+for (rr = dns_next_rr(dnsa, dnss, reset);
+ rr != NULL;
+ rr = dns_next_rr(dnsa, dnss, RESET_NEXT))
+ {
+ /* Check this is an address RR for the target hostname. */
+
+ if (rr->type != T_A
+ #if HAVE_IPV6
+ && rr->type != T_AAAA
+ #ifdef SUPPORT_A6
+ && rr->type != T_A6
+ #endif
+ #endif
+ ) continue;
+
+ if (strcmpic(target, rr->name) != 0) continue;
+
+ target_found = TRUE;
+
+ /* Turn the target address RR into a list of textual IP addresses and scan
+ the list. There may be more than one if it is an A6 RR. */
+
+ for (da = dns_address_from_rr(dnsa, rr); da != NULL; da = da->next)
+ {
+ /* If the client IP address matches the target IP address, it's good! */
+
+ DEBUG(D_acl) debug_printf("CSA target address is %s\n", da->address);
+
+ if (strcmpic(sender_host_address, da->address) == 0) return CSA_OK;
+ }
+ }
+
+/* If we found some target addresses but none of them matched, the client is
+using an unauthorized IP address, otherwise the target has no authorized IP
+addresses. */
+
+if (target_found) return CSA_FAIL_MISMATCH;
+else return CSA_FAIL_NOADDR;
+}
+
+
+
+/*************************************************
+* Verify Client SMTP Authorization *
+*************************************************/
+
+/* Called from acl_verify() below. This routine calls dns_lookup_special()
+to find the CSA SRV record corresponding to the domain argument, or
+$sender_helo_name if no argument is provided. It then checks that the
+client is authorized, and that its IP address corresponds to the SRV
+target's address by calling acl_verify_csa_address() above. The address
+should have been returned in the DNS response's ADDITIONAL section, but if
+not we perform another DNS lookup to get it.
+
+Arguments:
+ domain pointer to optional parameter following verify = csa
+
+Returns: CSA_UNKNOWN no valid CSA record found
+ CSA_OK successfully authorized
+ CSA_FAIL_* client is definitely not authorized
+ CSA_DEFER_* there was a DNS problem
+*/
+
+static int
+acl_verify_csa(uschar *domain)
+{
+tree_node *t;
+uschar *found, *p;
+int priority, weight, port;
+dns_answer dnsa;
+dns_scan dnss;
+dns_record *rr;
+int rc, type;
+uschar target[256];
+
+/* Work out the domain we are using for the CSA lookup. The default is the
+client's HELO domain. If the client has not said HELO, use its IP address
+instead. If it's a local client (exim -bs), CSA isn't applicable. */
+
+while (isspace(*domain) && *domain != '\0') ++domain;
+if (*domain == '\0') domain = sender_helo_name;
+if (domain == NULL) domain = sender_host_address;
+if (sender_host_address == NULL) return CSA_UNKNOWN;
+
+/* If we have an address literal, strip off the framing ready for turning it
+into a domain. The framing consists of matched square brackets possibly
+containing a keyword and a colon before the actual IP address. */
+
+if (domain[0] == '[')
+ {
+ uschar *start = Ustrchr(domain, ':');
+ if (start == NULL) start = domain;
+ domain = string_copyn(start + 1, Ustrlen(start) - 2);
+ }
+
+/* Turn domains that look like bare IP addresses into domains in the reverse
+DNS. This code also deals with address literals and $sender_host_address. It's
+not quite kosher to treat bare domains such as EHLO 192.0.2.57 the same as
+address literals, but it's probably the most friendly thing to do. This is an
+extension to CSA, so we allow it to be turned off for proper conformance. */
+
+if (string_is_ip_address(domain, NULL))
+ {
+ if (!dns_csa_use_reverse) return CSA_UNKNOWN;
+ dns_build_reverse(domain, target);
+ domain = target;
+ }
+
+/* Find out if we've already done the CSA check for this domain. If we have,
+return the same result again. Otherwise build a new cached result structure
+for this domain. The name is filled in now, and the value is filled in when
+we return from this function. */
+
+t = tree_search(csa_cache, domain);
+if (t != NULL) return t->data.val;
+
+t = store_get_perm(sizeof(tree_node) + Ustrlen(domain));
+Ustrcpy(t->name, domain);
+(void)tree_insertnode(&csa_cache, t);
+
+/* Now we are ready to do the actual DNS lookup(s). */
+
+switch (dns_special_lookup(&dnsa, domain, T_CSA, &found))
+ {
+ /* If something bad happened (most commonly DNS_AGAIN), defer. */
+
+ default:
+ return t->data.val = CSA_DEFER_SRV;
+
+ /* If we found nothing, the client's authorization is unknown. */
+
+ case DNS_NOMATCH:
+ case DNS_NODATA:
+ return t->data.val = CSA_UNKNOWN;
+
+ /* We got something! Go on to look at the reply in more detail. */
+
+ case DNS_SUCCEED:
+ break;
+ }
+
+/* Scan the reply for well-formed CSA SRV records. */
+
+for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
+ rr != NULL;
+ rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
+ {
+ if (rr->type != T_SRV) continue;
+
+ /* Extract the numerical SRV fields (p is incremented) */
+
+ p = rr->data;
+ GETSHORT(priority, p);
+ GETSHORT(weight, p);
+ GETSHORT(port, p);
+
+ DEBUG(D_acl)
+ debug_printf("CSA priority=%d weight=%d port=%d\n", priority, weight, port);
+
+ /* Check the CSA version number */
+
+ if (priority != 1) continue;
+
+ /* If the domain does not have a CSA SRV record of its own (i.e. the domain
+ found by dns_special_lookup() is a parent of the one we asked for), we check
+ the subdomain assertions in the port field. At the moment there's only one
+ assertion: legitimate SMTP clients are all explicitly authorized with CSA
+ SRV records of their own. */
+
+ if (found != domain)
+ {
+ if (port & 1)
+ return t->data.val = CSA_FAIL_EXPLICIT;
+ else
+ return t->data.val = CSA_UNKNOWN;
+ }
+
+ /* This CSA SRV record refers directly to our domain, so we check the value
+ in the weight field to work out the domain's authorization. 0 and 1 are
+ unauthorized; 3 means the client is authorized but we can't check the IP
+ address in order to authenticate it, so we treat it as unknown; values
+ greater than 3 are undefined. */
+
+ if (weight < 2) return t->data.val = CSA_FAIL_DOMAIN;
+
+ if (weight > 2) continue;
+
+ /* Weight == 2, which means the domain is authorized. We must check that the
+ client's IP address is listed as one of the SRV target addresses. Save the
+ target hostname then break to scan the additional data for its addresses. */
+
+ (void)dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p,
+ (DN_EXPAND_ARG4_TYPE)target, sizeof(target));
+
+ DEBUG(D_acl) debug_printf("CSA target is %s\n", target);
+
+ break;
+ }
+
+/* If we didn't break the loop then no appropriate records were found. */
+
+if (rr == NULL) return t->data.val = CSA_UNKNOWN;
+
+/* Do not check addresses if the target is ".", in accordance with RFC 2782.
+A target of "." indicates there are no valid addresses, so the client cannot
+be authorized. (This is an odd configuration because weight=2 target=. is
+equivalent to weight=1, but we check for it in order to keep load off the
+root name servers.) Note that dn_expand() turns "." into "". */
+
+if (Ustrcmp(target, "") == 0) return t->data.val = CSA_FAIL_NOADDR;
+
+/* Scan the additional section of the CSA SRV reply for addresses belonging
+to the target. If the name server didn't return any additional data (e.g.
+because it does not fully support SRV records), we need to do another lookup
+to obtain the target addresses; otherwise we have a definitive result. */
+
+rc = acl_verify_csa_address(&dnsa, &dnss, RESET_ADDITIONAL, target);
+if (rc != CSA_FAIL_NOADDR) return t->data.val = rc;
+
+/* The DNS lookup type corresponds to the IP version used by the client. */
+
+#if HAVE_IPV6
+if (Ustrchr(sender_host_address, ':') != NULL)
+ type = T_AAAA;
+else
+#endif /* HAVE_IPV6 */
+ type = T_A;
+
+
+#if HAVE_IPV6 && defined(SUPPORT_A6)
+DNS_LOOKUP_AGAIN:
+#endif
+
+switch (dns_lookup(&dnsa, target, type, NULL))
+ {
+ /* If something bad happened (most commonly DNS_AGAIN), defer. */
+
+ default:
+ return t->data.val = CSA_DEFER_ADDR;
+
+ /* If the query succeeded, scan the addresses and return the result. */
+
+ case DNS_SUCCEED:
+ rc = acl_verify_csa_address(&dnsa, &dnss, RESET_ANSWERS, target);
+ if (rc != CSA_FAIL_NOADDR) return t->data.val = rc;
+ /* else fall through */
+
+ /* If the target has no IP addresses, the client cannot have an authorized
+ IP address. However, if the target site uses A6 records (not AAAA records)
+ we have to do yet another lookup in order to check them. */
+
+ case DNS_NOMATCH:
+ case DNS_NODATA:
+
+ #if HAVE_IPV6 && defined(SUPPORT_A6)
+ if (type == T_AAAA) { type = T_A6; goto DNS_LOOKUP_AGAIN; }
+ #endif
+
+ return t->data.val = CSA_FAIL_NOADDR;
+ }
+}
+
+
+
/*************************************************
* Handle verification (address & other) *
*************************************************/
return helo_verified? OK : FAIL;
}
+/* Do Client SMTP Authorization checks in a separate function, and turn the
+result code into user-friendly strings. */
+
+if (strcmpic(ss, US"csa") == 0)
+ {
+ rc = acl_verify_csa(list);
+ *log_msgptr = *user_msgptr = string_sprintf("client SMTP authorization %s",
+ csa_reason_string[rc]);
+ csa_status = csa_status_string[rc];
+ DEBUG(D_acl) debug_printf("CSA result %s\n", csa_status);
+ return csa_return_code[rc];
+ }
+
/* Check that all relevant header lines have the correct syntax. If there is
a syntax error, we return details of the error to the sender if configured to
send out full details. (But a "message" setting on the ACL can override, as
{
uschar *pp = p + 1;
while (*pp != 0) pp++;
- fake_reject_text = expand_string(string_copyn(p+1, pp-p));
+ fake_reject_text = expand_string(string_copyn(p+1, pp-p-1));
p = pp;
}
else
break;
case CONTROL_SUBMISSION:
+ originator_name = US"";
submission_mode = TRUE;
while (*p == '/')
{
{
uschar *pp = p + 8;
while (*pp != 0 && *pp != '/') pp++;
- submission_domain = string_copyn(p+8, pp-p);
+ submission_domain = string_copyn(p+8, pp-p-8);
+ p = pp;
+ }
+ else if (Ustrncmp(p, "/name=", 6) == 0)
+ {
+ uschar *pp = p + 6;
+ while (*pp != 0 && *pp != '/') pp++;
+ originator_name = string_copy(parse_fix_phrase(p+6, pp-p-6,
+ big_buffer, big_buffer_size));
p = pp;
}
else break;
HDEBUG(D_acl)
debug_printf("delay skipped in -bh checking mode\n");
}
+
+ /* It appears to be impossible to detect that a TCP/IP connection has
+ gone away without reading from it. This means that we cannot shorten
+ the delay below if the client goes away, because we cannot discover
+ that the client has closed its end of the connection. (The connection
+ is actually in a half-closed state, waiting for the server to close its
+ end.) It would be nice to be able to detect this state, so that the
+ Exim process is not held up unnecessarily. However, it seems that we
+ can't. The poll() function does not do the right thing, and in any case
+ it is not always available.
+
+ NOTE: If ever this state of affairs changes, remember that we may be
+ dealing with stdin/stdout here, in addition to TCP/IP connections.
+ Whatever is done must work in both cases. To detected the stdin/stdout
+ case, check for smtp_in or smtp_out being NULL. */
+
else
{
while (delay > 0) delay = sleep(delay);
/* If the verb is WARN, discard any user message from verification, because
such messages are SMTP responses, not header additions. The latter come
- only from explicit "message" modifiers. */
+ only from explicit "message" modifiers. However, put the user message into
+ $acl_verify_message so it can be used in subsequent conditions or modifiers
+ (until something changes it). */
case ACLC_VERIFY:
rc = acl_verify(where, addr, arg, user_msgptr, log_msgptr, basic_errno);
+ acl_verify_message = *user_msgptr;
if (verb == ACL_WARN) *user_msgptr = NULL;
break;
if (cond == OK)
acl_warn(where, *user_msgptr, *log_msgptr);
else if (cond == DEFER)
- acl_warn(where, NULL, string_sprintf("ACL \"warn\" statement skipped: "
- "condition test deferred: %s",
- (*log_msgptr == NULL)? US"" : *log_msgptr));
+ log_write(0, LOG_MAIN, "%s Warning: ACL \"warn\" statement skipped: "
+ "condition test deferred%s%s", host_and_ident(TRUE),
+ (*log_msgptr == NULL)? US"" : US": ",
+ (*log_msgptr == NULL)? US"" : *log_msgptr);
*log_msgptr = *user_msgptr = NULL; /* In case implicit DENY follows */
break;
git://git.exim.org / users / jgh / exim.git / blobdiff