Gitweb:
https://git.exim.org/exim.git/commitdiff/fcb900d84cc71cb169bd1b223920de1026772695
Commit: fcb900d84cc71cb169bd1b223920de1026772695
Parent: ae75164b86600394f3e271a3d54bb88d946eb924
Author: Jeremy Harris <jgh146exb@???>
AuthorDate: Sat Jan 5 19:11:18 2019 +0000
Committer: Jeremy Harris <jgh146exb@???>
CommitDate: Sat Jan 5 19:11:18 2019 +0000
Docs: tweak TLS authenticator chapter
---
doc/doc-docbook/spec.xfpt | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 2d69e1a..25e3507 100644
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -26607,7 +26607,7 @@ to be returned. If the result of a successful expansion is an empty string,
expansion is &"1"&, &"yes"&, or &"true"&, authentication succeeds and the
generic &%server_set_id%& option is expanded and saved in &$authenticated_id$&.
For any other result, a temporary error code is returned, with the expanded
-string as the error text
+string as the error text.
&*Warning*&: If you use a lookup in the expansion to find the user's
password, be sure to make the authentication fail if the user is unknown.
@@ -27435,20 +27435,25 @@ tls:
driver = tls
server_param1 = ${certextract {subj_altname,mail,>:} \
{$tls_in_peercert}}
- server_condition = ${if forany {$auth1} \
+ server_condition = ${if and { {eq{$tls_in_certificate_verified}{1}} \
+ {forany {$auth1} \
{!= {0} \
{${lookup ldap{ldap:///\
mailname=${quote_ldap_dn:${lc:$item}},\
ou=users,LDAP_DC?mailid} {$value}{0} \
- } } } }
+ } } } }}}
server_set_id = ${if = {1}{${listcount:$auth1}} {$auth1}{}}
.endd
This accepts a client certificate that is verifiable against any
of your configured trust-anchors
(which usually means the full set of public CAs)
and which has a SAN with a good account name.
-Note that the client cert is on the wire in-clear, including the SAN,
-whereas a plaintext SMTP AUTH done inside TLS is not.
+
+Note that, up to TLS1.2, the client cert is on the wire in-clear, including the SAN,
+The account name is therefore guessable by an opponent.
+TLS 1.3 protects both server and client certificates, and is not vulnerable
+in this way.
+Likewise, a traditional plaintext SMTP AUTH done inside TLS is not.
. An alternative might use
. .code
