| 1 | ### -*-m4-*- |
| 2 | ### |
| 3 | ### Client authentication for distorted.org.uk Exim configuration |
| 4 | ### |
| 5 | ### (c) 2012 Mark Wooding |
| 6 | ### |
| 7 | |
| 8 | ###----- Licensing notice --------------------------------------------------- |
| 9 | ### |
| 10 | ### This program is free software; you can redistribute it and/or modify |
| 11 | ### it under the terms of the GNU General Public License as published by |
| 12 | ### the Free Software Foundation; either version 2 of the License, or |
| 13 | ### (at your option) any later version. |
| 14 | ### |
| 15 | ### This program is distributed in the hope that it will be useful, |
| 16 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | ### GNU General Public License for more details. |
| 19 | ### |
| 20 | ### You should have received a copy of the GNU General Public License |
| 21 | ### along with this program; if not, write to the Free Software Foundation, |
| 22 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 23 | |
| 24 | ###-------------------------------------------------------------------------- |
| 25 | ### Authenticators. |
| 26 | |
| 27 | m4_define(<:CHECK_PASSWD:>, |
| 28 | <:${lookup {$1} lsearch {CONF_sysconf_dir/passwd} \ |
| 29 | {${if crypteq {$2} {$value}}} \ |
| 30 | {false}}:>) |
| 31 | |
| 32 | m4_define(<:ALLOW_PLAINTEXT_AUTH_P:>, |
| 33 | <:or {{match_ip {$sender_host_address}{+thishost}} \ |
| 34 | {and {{def:tls_cipher} {eq{$acl_c_mode}{submission}}}}}:>) |
| 35 | |
| 36 | m4_define(<:CLIENT_SECRETS_FILE:>, <:CONF_sysconf_dir/client-secrets:>) |
| 37 | |
| 38 | m4_define(<:CLIENT_SECRET_GET:>, |
| 39 | <:${if exists {CLIENT_SECRETS_FILE} \ |
| 40 | {${lookup {$domain} partial0-lsearch {CLIENT_SECRETS_FILE} \ |
| 41 | {${extract {$1}{$value}$2$3}} \ |
| 42 | {${lookup {$host} partial0-lsearch {CLIENT_SECRETS_FILE} \ |
| 43 | {${extract {$1}{$value}$2$3}} $3}}}} \ |
| 44 | $3}:>) |
| 45 | |
| 46 | m4_define(<:CLIENT_SECRET_EXISTSP:>, |
| 47 | <:CLIENT_SECRET_GET($1, {true}, {false}):>) |
| 48 | |
| 49 | m4_define(<:CLIENT_SECRET:>, |
| 50 | <:CLIENT_SECRET_GET($1, {${expand:$value}}, fail):>) |
| 51 | |
| 52 | SECTION(auth)m4_dnl |
| 53 | plain: |
| 54 | driver = plaintext |
| 55 | public_name = PLAIN |
| 56 | server_advertise_condition = ${if ALLOW_PLAINTEXT_AUTH_P} |
| 57 | server_prompts = : |
| 58 | server_condition = CHECK_PASSWD($auth2, $auth3) |
| 59 | server_set_id = $auth2 |
| 60 | client_condition = CLIENT_SECRET_EXISTSP(plain) |
| 61 | client_send = <; CLIENT_SECRET(plain) |
| 62 | |
| 63 | login: |
| 64 | driver = plaintext |
| 65 | public_name = LOGIN |
| 66 | server_advertise_condition = ${if ALLOW_PLAINTEXT_AUTH_P} |
| 67 | server_prompts = <; Username: ; Password: |
| 68 | server_condition = CHECK_PASSWD($auth1, $auth2) |
| 69 | server_set_id = $auth1 |
| 70 | client_condition = CLIENT_SECRET_EXISTSP(login-passwd) |
| 71 | client_send = <; \ |
| 72 | ; CLIENT_SECRET(login-name) \ |
| 73 | ; CLIENT_SECRET(login-passwd) |
| 74 | |
| 75 | cram_md5: |
| 76 | driver = cram_md5 |
| 77 | public_name = CRAM-MD5 |
| 78 | client_condition = CLIENT_SECRET_EXISTSP(cram-md5-secret) |
| 79 | client_name = CLIENT_SECRET(cram-md5-name) |
| 80 | client_secret = CLIENT_SECRET(cram-md5-secret) |
| 81 | |
| 82 | DIVERT(null) |
| 83 | ###-------------------------------------------------------------------------- |
| 84 | ### Dealing with `AUTH' parameters and relaying. |
| 85 | |
| 86 | SECTION(global, acl)m4_dnl |
| 87 | acl_smtp_mailauth = mailauth |
| 88 | SECTION(acl, misc)m4_dnl |
| 89 | ## Check the `AUTH=...' parameter to a `MAIL' command. |
| 90 | mailauth: |
| 91 | ## If the client has authenticated using TLS then we're OK. The |
| 92 | ## sender was presumably checked upstream, and we can believe that |
| 93 | ## the name has been transmitted honestly. |
| 94 | accept condition = ${if def:tls_peerdn} |
| 95 | |
| 96 | ## If this is submission, and the client has authenticated, then we |
| 97 | ## check that the name matches the user. |
| 98 | accept condition = ${if eq {$authenticated_sender} \ |
| 99 | {$authenticated_id@CONF_master_domain}} |
| 100 | |
| 101 | ## Otherwise we can't tell who really sent it. |
| 102 | deny message = Authenticated user not authoritative for claimed sender. |
| 103 | |
| 104 | DIVERT(null) |
| 105 | ###----- That's all, folks -------------------------------------------------- |