rpms/exim/devel exim-csa.patch, NONE, 1.1 .cvsignore, 1.3, 1.4 exim.spec, 1.2, 1.3 sources, 1.3, 1.4 exim-4.51-csa.2c.patch, 1.1, NONE
David Woodhouse (dwmw2)
fedora-extras-commits at redhat.com
Thu Jun 16 11:17:07 UTC 2005
Author: dwmw2
Update of /cvs/extras/rpms/exim/devel
In directory cvs-int.fedora.redhat.com:/tmp/cvs-serv31017/devel
Modified Files:
.cvsignore exim.spec sources
Added Files:
exim-csa.patch
Removed Files:
exim-4.51-csa.2c.patch
Log Message:
auto-import exim-4.51-2 on branch devel from exim-4.51-2.src.rpm
exim-csa.patch:
--- NEW FILE exim-csa.patch ---
--- doc/ChangeLog 4 May 2005 10:17:28 -0000 1.133
+++ doc/ChangeLog 10 May 2005 10:19:11 -0000 1.134
@@ -1,7 +1,13 @@
-$Cambridge: exim/exim-doc/doc-txt/ChangeLog,v 1.133 2005/05/04 10:17:28 ph10 Exp $
+$Cambridge: exim/exim-doc/doc-txt/ChangeLog,v 1.134 2005/05/10 10:19:11 ph10 Exp $
Change log file for Exim from version 4.21
-------------------------------------------
+
+
+Exim version 4.52
+-----------------
+
+TF/01 Added support for Client SMTP Authorization. See NewStuff for details.
Exim version 4.51
--- doc/NewStuff 3 May 2005 14:20:00 -0000 1.39
+++ doc/NewStuff 10 May 2005 10:19:11 -0000 1.40
@@ -7,6 +7,66 @@
but have not yet made it into the main manual (which is most conveniently
updated when there is a relatively large batch of changes). The doc/ChangeLog
file contains a listing of all changes, including bug fixes.
+
+
+Exim version 4.52
+-----------------
+
+TF/01 Support for checking Client SMTP Authorization has been added. CSA is a
+ system which allows a site to advertise which machines are and are not
+ permitted to send email. This is done by placing special SRV records in
+ the DNS, which are looked up using the client's HELO domain. At this
+ time CSA is still an Internet-Draft.
+
+ Client SMTP Authorization checks are performed by the ACL condition
+ verify=csa. This will fail if the client is not authorized. If there is
+ a DNS problem, or if no valid CSA SRV record is found, or if the client
+ is authorized, the condition succeeds. These three cases can be
+ distinguished using the expansion variable $csa_status, which can take
+ one of the values "fail", "defer", "unknown", or "ok". The condition
+ does not itself defer because that would be likely to cause problems
+ for legitimate email.
+
+ The error messages produced by the CSA code include slightly more
+ detail. If $csa_status is "defer" this may be because of problems
+ looking up the CSA SRV record, or problems looking up the CSA target
+ address record. There are four reasons for $csa_status being "fail":
+ the client's host name is explicitly not authorized; the client's IP
+ address does not match any of the CSA target IP addresses; the client's
+ host name is authorized but it has no valid target IP addresses (e.g.
+ the target's addresses are IPv6 and the client is using IPv4); or the
+ client's host name has no CSA SRV record but a parent domain has
+ asserted that all subdomains must be explicitly authorized.
+
+ The verify=csa condition can take an argument which is the domain to
+ use for the DNS query. The default is verify=csa/$sender_helo_name.
+
+ This implementation includes an extension to CSA. If the query domain
+ is an address literal such as [192.0.2.95], or if it is a bare IP
+ address, Exim will search for CSA SRV records in the reverse DNS as if
+ the HELO domain was e.g. 95.2.0.192.in-addr.arpa. Therefore it is
+ meaningful to say, for example, verify=csa/$sender_host_address - in
+ fact, this is the check that Exim performs if the client does not say
+ HELO. This extension can be turned off by setting the main
+ configuration option dns_csa_use_reverse = false.
+
+ If a CSA SRV record is not found for the domain itself, then a search
+ is performed through its parent domains for a record which might be
+ making assertions about subdomains. The maximum depth of this search is
+ limited using the main configuration option dns_csa_search_limit, which
+ takes the value 5 by default. Exim does not look for CSA SRV records in
+ a top level domain, so the default settings handle HELO domains as long
+ as seven (hostname.five.four.three.two.one.com) which encompasses the
+ vast majority of legitimate HELO domains.
+
+ The dnsdb lookup also has support for CSA. Although dnsdb already
+ supports SRV lookups, this is not sufficient because of the extra
+ parent domain search behaviour of CSA, and (as with PTR lookups)
+ dnsdb also turns IP addresses into lookups in the reverse DNS space.
+ The result of ${lookup dnsdb {csa=$sender_helo_name} } has two
+ space-separated fields: an authorization code and a target host name.
+ The authorization code can be "Y" for yes, "N" for no, "X" for explicit
+ authorization required but absent, or "?" for unknown.
Version 4.51
--- src/acl.c 6 Apr 2005 14:03:53 -0000 1.28
+++ src/acl.c 10 May 2005 10:19:11 -0000 1.29
@@ -505,6 +505,45 @@
{ 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 **,
@@ -938,6 +977,304 @@
/*************************************************
+* 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). */
+
+found = domain;
+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) *
*************************************************/
@@ -1017,6 +1353,19 @@
{
if (slash != NULL) goto NO_OPTIONS;
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
--- src/dns.c 17 Feb 2005 11:58:26 -0000 1.5
+++ src/dns.c 10 May 2005 10:19:11 -0000 1.6
@@ -153,9 +153,9 @@
*************************************************/
/* Call this with reset == RESET_ANSWERS to scan the answer block, reset ==
-RESET_ADDITIONAL to scan the additional records, and reset == RESET_NEXT to
-get the next record. The result is in static storage which must be copied if
-it is to be preserved.
+RESET_AUTHORITY to scan the authority records, reset == RESET_ADDITIONAL to
+scan the additional records, and reset == RESET_NEXT to get the next record.
+The result is in static storage which must be copied if it is to be preserved.
Arguments:
dnsa pointer to dns answer block
@@ -192,12 +192,14 @@
dnss->rrcount = ntohs(h->ancount);
- /* Skip over answers and NS records if wanting to look at the additional
+ /* Skip over answers if we want to look at the authority section. Also skip
+ the NS records (i.e. authority section) if wanting to look at the additional
records. */
- if (reset == RESET_ADDITIONAL)
+ if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount);
+
+ if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL)
{
- dnss->rrcount += ntohs(h->nscount);
while (dnss->rrcount-- > 0)
{
namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen,
@@ -207,11 +209,11 @@
GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */
dnss->aptr += dnss->srr.size; /* skip over it */
}
- dnss->rrcount = ntohs(h->arcount);
+ dnss->rrcount = (reset == RESET_AUTHORITY)
+ ? ntohs(h->nscount) : ntohs(h->arcount);
}
}
-
/* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount
contains the number of RR records left. */
@@ -666,6 +668,153 @@
if (rc != DNS_NOMATCH && rc != DNS_NODATA) return rc;
while (*d != 0 && *d != '.') d++;
if (*d++ == 0) break;
+ }
+ return DNS_NOMATCH;
+ }
+
+/* Try to look up the Client SMTP Authorization SRV record for the name. If
+there isn't one, search from the top downwards for a CSA record in a parent
+domain, which might be making assertions about subdomains. If we find a record
+we set fully_qualified_name to whichever lookup succeeded, so that the caller
+can tell whether to look at the explicit authorization field or the subdomain
+assertion field. */
+
+if (type == T_CSA)
+ {
+ uschar *srvname, *namesuff, *tld, *p;
+ int priority, weight, port;
+ int limit, rc, i;
+ BOOL ipv6;
+ dns_record *rr;
+ dns_scan dnss;
+
+ DEBUG(D_dns) debug_printf("CSA lookup of %s\n", name);
+
+ srvname = string_sprintf("_client._smtp.%s", name);
+ rc = dns_lookup(dnsa, srvname, T_SRV, NULL);
+ if (rc == DNS_SUCCEED || rc == DNS_AGAIN)
+ {
+ if (rc == DNS_SUCCEED) *fully_qualified_name = name;
+ return rc;
+ }
+
+ /* Search for CSA subdomain assertion SRV records from the top downwards,
+ starting with the 2nd level domain. This order maximizes cache-friendliness.
+ We skip the top level domains to avoid loading their nameservers and because
+ we know they'll never have CSA SRV records. */
+
+ namesuff = Ustrrchr(name, '.');
+ if (namesuff == NULL) return DNS_NOMATCH;
+ tld = namesuff + 1;
+ ipv6 = FALSE;
+ limit = dns_csa_search_limit;
+
+ /* Use more appropriate search parameters if we are in the reverse DNS. */
+
+ if (strcmpic(namesuff, US".arpa") == 0)
+ {
+ if (namesuff - 8 > name && strcmpic(namesuff - 8, US".in-addr.arpa") == 0)
+ {
+ namesuff -= 8;
+ tld = namesuff + 1;
+ limit = 3;
+ }
+ else if (namesuff - 4 > name && strcmpic(namesuff - 4, US".ip6.arpa") == 0)
+ {
+ namesuff -= 4;
+ tld = namesuff + 1;
+ ipv6 = TRUE;
+ limit = 3;
+ }
+ }
+
+ DEBUG(D_dns) debug_printf("CSA TLD %s\n", tld);
+
+ /* Do not perform the search if the top level or 2nd level domains do not
+ exist. This is quite common, and when it occurs all the search queries would
+ go to the root or TLD name servers, which is not friendly. So we check the
+ AUTHORITY section; if it contains the root's SOA record or the TLD's SOA then
+ the TLD or the 2LD (respectively) doesn't exist and we can skip the search.
+ If the TLD and the 2LD exist but the explicit CSA record lookup failed, then
+ the AUTHORITY SOA will be the 2LD's or a subdomain thereof. */
+
+ if (rc == DNS_NOMATCH)
+ {
+ /* This is really gross. The successful return value from res_search() is
+ the packet length, which is stored in dnsa->answerlen. If we get a
+ negative DNS reply then res_search() returns -1, which causes the bounds
+ checks for name decompression to fail when it is treated as a packet
+ length, which in turn causes the authority search to fail. The correct
+ packet length has been lost inside libresolv, so we have to guess a
+ replacement value. (The only way to fix this properly would be to
+ re-implement res_search() and res_query() so that they don't muddle their
+ success and packet length return values.) For added safety we only reset
+ the packet length if the packet header looks plausible. */
+
+ HEADER *h = (HEADER *)dnsa->answer;
+ if (h->qr == 1 && h->opcode == QUERY && h->tc == 0
+ && (h->rcode == NOERROR || h->rcode == NXDOMAIN)
+ && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0
+ && ntohs(h->nscount) >= 1)
+ dnsa->answerlen = MAXPACKET;
+
+ for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
+ rr != NULL;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+ if (rr->type != T_SOA) continue;
+ else if (strcmpic(rr->name, US"") == 0 ||
+ strcmpic(rr->name, tld) == 0) return DNS_NOMATCH;
+ else break;
+ }
+
+ for (i = 0; i < limit; i++)
+ {
+ if (ipv6)
+ {
+ /* Scan through the IPv6 reverse DNS in chunks of 16 bits worth of IP
+ address, i.e. 4 hex chars and 4 dots, i.e. 8 chars. */
+ namesuff -= 8;
+ if (namesuff <= name) return DNS_NOMATCH;
+ }
+ else
+ /* Find the start of the preceding domain name label. */
+ do
+ if (--namesuff <= name) return DNS_NOMATCH;
+ while (*namesuff != '.');
+
+ DEBUG(D_dns) debug_printf("CSA parent search at %s\n", namesuff + 1);
+
+ srvname = string_sprintf("_client._smtp.%s", namesuff + 1);
+ rc = dns_lookup(dnsa, srvname, T_SRV, NULL);
+ if (rc == DNS_AGAIN) return rc;
+ if (rc != DNS_SUCCEED) continue;
+
+ /* Check that the SRV record we have found is worth returning. We don't
+ just return the first one we find, because some lower level SRV record
+ might make stricter assertions than its parent domain. */
+
+ 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);
+
+ /* Check the CSA version number */
+ if (priority != 1) continue;
+
+ /* If it's making an interesting assertion, return this response. */
+ if (port & 1)
+ {
+ *fully_qualified_name = namesuff + 1;
+ return DNS_SUCCEED;
+ }
+ }
}
return DNS_NOMATCH;
}
--- src/exim.h 27 Apr 2005 10:00:18 -0000 1.11
+++ src/exim.h 10 May 2005 10:19:11 -0000 1.12
@@ -280,12 +280,19 @@
#define T_SRV 33
#endif
-/* We use the private type T_ZNS for retrieving the nameservers for the
-enclosing zone of a domain, and the private type T_MXH for retrieving
-the MX hostnames only (without their priorities). */
+/* We define a few private types for special DNS lookups:
+
+ . T_ZNS gets the nameservers of the enclosing zone of a domain
+
+ . T_MXH gets the MX hostnames only (without their priorities)
+
+ . T_CSA gets the domain's Client SMTP Authorization SRV record
+
+*/
#define T_ZNS (-1)
#define T_MXH (-2)
+#define T_CSA (-3)
/* The resolv.h header defines __P(x) on some Solaris 2.5.1 systems (without
checking that it is already defined, in fact). This conflicts with other
--- src/expand.c 28 Apr 2005 13:29:27 -0000 1.20
+++ src/expand.c 10 May 2005 10:19:11 -0000 1.21
@@ -333,6 +333,7 @@
{ "caller_uid", vtype_uid, &real_uid },
{ "compile_date", vtype_stringptr, &version_date },
{ "compile_number", vtype_stringptr, &version_cnumber },
+ { "csa_status", vtype_stringptr, &csa_status },
#ifdef WITH_OLD_DEMIME
{ "demime_errorlevel", vtype_int, &demime_errorlevel },
{ "demime_reason", vtype_stringptr, &demime_reason },
--- src/globals.c 3 May 2005 14:20:01 -0000 1.23
+++ src/globals.c 10 May 2005 10:19:11 -0000 1.24
@@ -385,6 +385,8 @@
int continue_sequence = 1;
uschar *continue_transport = NULL;
+uschar *csa_status = NULL;
+
BOOL daemon_listen = FALSE;
uschar *daemon_smtp_port = US"smtp";
BOOL debug_daemon = FALSE;
@@ -473,6 +475,8 @@
#endif
uschar *dns_again_means_nonexist = NULL;
+int dns_csa_search_limit = 5;
+BOOL dns_csa_use_reverse = TRUE;
uschar *dns_ipv4_lookup = NULL;
int dns_retrans = 0;
int dns_retry = 0;
--- src/globals.h 3 May 2005 14:20:01 -0000 1.15
+++ src/globals.h 10 May 2005 10:19:11 -0000 1.16
@@ -214,6 +214,8 @@
extern int continue_sequence; /* Sequence num for continued delivery */
extern uschar *continue_transport; /* Transport for continued delivery */
+extern uschar *csa_status; /* Client SMTP Authorization result */
+
extern BOOL daemon_listen; /* True if listening required */
extern uschar *daemon_smtp_port; /* Can be a list of ports */
extern BOOL debug_daemon; /* Debug the daemon process only */
@@ -271,6 +273,8 @@
#endif
extern uschar *dns_again_means_nonexist; /* Domains that are badly set up */
+extern int dns_csa_search_limit; /* How deep to search for CSA SRV records */
+extern BOOL dns_csa_use_reverse; /* Check CSA in reverse DNS? (non-standard) */
extern uschar *dns_ipv4_lookup; /* For these domains, don't look for AAAA (or A6) */
extern int dns_retrans; /* Retransmission time setting */
extern int dns_retry; /* Number of retries */
--- src/macros.h 7 Apr 2005 10:54:54 -0000 1.12
+++ src/macros.h 10 May 2005 10:19:11 -0000 1.13
@@ -178,7 +178,7 @@
/* Options for dns_next_rr */
-enum { RESET_NEXT, RESET_ANSWERS, RESET_ADDITIONAL };
+enum { RESET_NEXT, RESET_ANSWERS, RESET_AUTHORITY, RESET_ADDITIONAL };
/* Argument values for the time-of-day function */
--- src/readconf.c 5 Apr 2005 13:58:35 -0000 1.7
+++ src/readconf.c 10 May 2005 10:19:11 -0000 1.8
@@ -193,6 +193,8 @@
{ "delivery_date_remove", opt_bool, &delivery_date_remove },
{ "dns_again_means_nonexist", opt_stringptr, &dns_again_means_nonexist },
{ "dns_check_names_pattern", opt_stringptr, &check_dns_names_pattern },
+ { "dns_csa_search_limit", opt_int, &dns_csa_search_limit },
+ { "dns_csa_use_reverse", opt_bool, &dns_csa_use_reverse },
{ "dns_ipv4_lookup", opt_stringptr, &dns_ipv4_lookup },
{ "dns_retrans", opt_time, &dns_retrans },
{ "dns_retry", opt_int, &dns_retry },
--- src/lookups/dnsdb.c 17 Feb 2005 11:58:27 -0000 1.10
+++ src/lookups/dnsdb.c 10 May 2005 10:19:11 -0000 1.11
@@ -31,6 +31,7 @@
#endif
#endif
"cname",
+ "csa",
"mx",
"mxh",
"ns",
@@ -49,6 +50,7 @@
#endif
#endif
T_CNAME,
+ T_CSA, /* Private type for "Client SMTP Authorization". */
T_MX,
T_MXH, /* Private type for "MX hostnames" */
T_NS,
@@ -112,7 +114,7 @@
int type = T_TXT;
int failrc = FAIL;
uschar *outsep = US"\n";
-uschar *equals, *domain;
+uschar *equals, *domain, *found;
uschar buffer[256];
/* Because we're the working in the search pool, we try to reclaim as much
@@ -228,15 +230,18 @@
!= NULL)
{
uschar rbuffer[256];
- int searchtype = (type == T_ZNS)? T_NS : /* record type we want */
- (type == T_MXH)? T_MX : type;
+ int searchtype = (type == T_CSA)? T_SRV : /* record type we want */
+ (type == T_MXH)? T_MX :
+ (type == T_ZNS)? T_NS : type;
+
+ /* If the type is PTR or CSA, we have to construct the relevant magic lookup
+ key if the original is an IP address (some experimental protocols are using
+ PTR records for different purposes where the key string is a host name, and
+ Exim's extended CSA can be keyed by domains or IP addresses). This code for
+ doing the reversal is now in a separate function. */
- /* If the type is PTR, we have to construct the relevant magic lookup key if
- the original is an IP address (some experimental protocols are using PTR
- records for different purposes where the key string is a host name). This
- code for doing the reversal is now in a separate function. */
-
- if (type == T_PTR && string_is_ip_address(domain, NULL) > 0)
+ if ((type == T_PTR || type == T_CSA) &&
+ string_is_ip_address(domain, NULL) > 0)
{
dns_build_reverse(domain, rbuffer);
domain = rbuffer;
@@ -244,15 +249,16 @@
DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", domain);
- /* Do the lookup and sort out the result. There are two special types that
- are handled specially: T_ZNS and T_MXH. The former is handled in a special
- lookup function so that the facility could be used from other parts of the
- Exim code. The latter affects only what happens later on in this function,
- but for tidiness it is handled in a similar way. If the lookup fails,
- continue with the next domain. In the case of DEFER, adjust the final
- "nothing found" result, but carry on to the next domain. */
+ /* Do the lookup and sort out the result. There are three special types that
+ are handled specially: T_CSA, T_ZNS and T_MXH. The former two are handled in
+ a special lookup function so that the facility could be used from other
+ parts of the Exim code. The latter affects only what happens later on in
+ this function, but for tidiness it is handled in a similar way. If the
+ lookup fails, continue with the next domain. In the case of DEFER, adjust
+ the final "nothing found" result, but carry on to the next domain. */
- rc = dns_special_lookup(&dnsa, domain, type, NULL);
+ found = domain;
+ rc = dns_special_lookup(&dnsa, domain, type, &found);
if (rc == DNS_NOMATCH || rc == DNS_NODATA) continue;
if (rc != DNS_SUCCEED)
@@ -300,32 +311,63 @@
yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1),
(rr->data)[0]);
}
- else /* T_CNAME, T_MX, T_MXH, T_NS, T_SRV, T_PTR */
+ else /* T_CNAME, T_CSA, T_MX, T_MXH, T_NS, T_PTR, T_SRV */
{
- int num;
+ int priority, weight, port;
uschar s[264];
uschar *p = (uschar *)(rr->data);
if (type == T_MXH)
{
/* mxh ignores the priority number and includes only the hostnames */
- GETSHORT(num, p); /* pointer is advanced */
+ GETSHORT(priority, p);
}
else if (type == T_MX)
{
- GETSHORT(num, p); /* pointer is advanced */
- sprintf(CS s, "%d ", num);
+ GETSHORT(priority, p);
+ sprintf(CS s, "%d ", priority);
yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
}
else if (type == T_SRV)
{
- int weight, port;
- GETSHORT(num, p); /* pointer is advanced */
+ GETSHORT(priority, p);
GETSHORT(weight, p);
GETSHORT(port, p);
- sprintf(CS s, "%d %d %d ", num, weight, port);
+ sprintf(CS s, "%d %d %d ", priority, weight, port);
yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
}
+ else if (type == T_CSA)
+ {
+ /* See acl_verify_csa() for more comments about CSA. */
+
+ GETSHORT(priority, p);
+ GETSHORT(weight, p);
+ GETSHORT(port, p);
+
+ if (priority != 1) continue; /* CSA version must be 1 */
+
+ /* If the CSA record we found is not the one we asked for, analyse
+ the subdomain assertions in the port field, else analyse the direct
+ authorization status in the weight field. */
+
+ if (found != domain)
+ {
+ if (port & 1) *s = 'X'; /* explicit authorization required */
+ else *s = '?'; /* no subdomain assertions here */
+ }
+ else
+ {
+ if (weight < 2) *s = 'N'; /* not authorized */
+ else if (weight == 2) *s = 'Y'; /* authorized */
+ else if (weight == 3) *s = '?'; /* unauthorizable */
+ else continue; /* invalid */
+ }
+
+ s[1] = ' ';
+ yield = string_cat(yield, &size, &ptr, s, 2);
+ }
+
+ /* GETSHORT() has advanced the pointer to the target domain. */
rc = dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p,
(DN_EXPAND_ARG4_TYPE)(s), sizeof(s));
--- src/configure.default 29 Mar 2005 09:49:49 -0000 1.2
+++ src/configure.default 10 May 2005 14:48:07 -0000 1.3
@@ -322,6 +322,17 @@
# warn message = X-Warning: $sender_host_address is in a black list at $dnslist_domain
# log_message = found in $dnslist_domain
# dnslists = black.list.example
+ #############################################################################
+
+ #############################################################################
+ # This check is commented out because it is recognized that not every
+ # sysadmin will want to do it. If you enable it, the check performs
+ # Client SMTP Authorization (csa) checks on the sending host. These checks
+ # do DNS lookups for SRV records. The CSA proposal is currently (May 2005)
+ # an Internet draft. You can, of course, add additional conditions to this
+ # ACL statement to restrict the CSA checks to certain hosts only.
+ #
+ # require verify = csa
#############################################################################
# Accept if the address is in a local domain, but only if the recipient can
Index: .cvsignore
===================================================================
RCS file: /cvs/extras/rpms/exim/devel/.cvsignore,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- .cvsignore 4 May 2005 16:30:44 -0000 1.3
+++ .cvsignore 16 Jun 2005 11:17:05 -0000 1.4
@@ -1,2 +1,2 @@
-sa-exim-4.2.tar.gz
exim-4.51.tar.bz2
+sa-exim-4.2.tar.gz
Index: exim.spec
===================================================================
RCS file: /cvs/extras/rpms/exim/devel/exim.spec,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- exim.spec 4 May 2005 16:30:44 -0000 1.2
+++ exim.spec 16 Jun 2005 11:17:05 -0000 1.3
@@ -1,7 +1,7 @@
Summary: The exim mail transfer agent
Name: exim
Version: 4.51
-Release: 1
+Release: 2
License: GPL
Url: http://www.exim.org/
Group: System Environment/Daemons
@@ -25,7 +25,7 @@
Patch12: exim-4.33-cyrus.patch
Patch13: exim-4.43-pamconfig.patch
Patch14: exim-4.50-spamdconf.patch
-Patch15: exim-4.51-csa.2c.patch
+Patch15: http://www.cus.cam.ac.uk/~fanf2/hermes/doc/antiforgery/exim-csa.patch
Requires: /etc/aliases
BuildRequires: db4-devel openssl-devel openldap-devel XFree86-devel pam-devel
@@ -78,7 +78,7 @@
%patch12 -p1 -b .cyrus
%patch13 -p1 -b .pam
%patch14 -p1 -b .spamd
-%patch15 -p0 -b .csa.2c
+%patch15 -p0 -b .csa
%build
%ifnarch s390 s390x
@@ -287,6 +287,9 @@
%doc sa-exim*/{ACKNOWLEDGEMENTS,INSTALL,LICENSE,TODO}
%changelog
+* Wed May 4 2005 David Woodhouse <dwmw2 at redhat.com> 4.51-2
+- Update CSA patch
+
* Wed May 4 2005 David Woodhouse <dwmw2 at redhat.com> 4.51-1
- Update to Exim 4.51
- Include Tony's CSA support patch
Index: sources
===================================================================
RCS file: /cvs/extras/rpms/exim/devel/sources,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- sources 4 May 2005 16:30:44 -0000 1.3
+++ sources 16 Jun 2005 11:17:05 -0000 1.4
@@ -1,2 +1,2 @@
-ad76f73c6b3d01caa88078e3e622745a sa-exim-4.2.tar.gz
36c0c005e012d13beb7edfd8d124c049 exim-4.51.tar.bz2
+ad76f73c6b3d01caa88078e3e622745a sa-exim-4.2.tar.gz
--- exim-4.51-csa.2c.patch DELETED ---
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