[Dovecot] When the subject portion of an e-mail contains a control character, dovecot.sieve terminates unexpectatedly.
Hello.
We have currently set dovecot.sieve to insert the text "[SPAM]" at the beginning of an e-mail's subject when it's X-Spam-Score is above 80%. After we set our system as stated the following errors occur:
- When an e-mail's subject contains control characters like [Ctrl+V|^V], dovecot.sieve terminates with an error and an e-mail is not able to be sent. When a MIME encoded Subject like [ＴＥＳＴ^VＭＡＩＬ] is sent we're not able to edit the subject and dovecot ends with an error.
This is a sample of the data that was used in testing. Subject: =?ISO-2022-JP?B?GyRCI1QjRSNTI1QbKEIWGyRCI00jQSNJI0wbKEI=?= X-Spam-Score: 100.00% ↓ Subject: =?ISO-2022-JP?B?GyRCI1QjRSNTI1QbKEIWGyRCI00jQSNJI0wbKEI=?= X-Spam-Score: 100.00%
This is the log generated by the data above.
sieve: info: started log at May 02 10:46:22. main script: line 14: error: addheader action: specified value `[SPAM] ＴＥＳＴ?・・' is invalid.
Aside from [Ctrl + V] the following control charcters also cause errors: backspace Ctrl + A Ctrl + C Ctrl + [ Ctrl + X Ctrl + Y
- When an e-mail's subject line contains a "\0" character, everything following the null character is deleted. When a MIME encoded Subject is sent, for example "ＴＥＳＴ\0ＭＡＩＬ", the subject becomes "[SPAM]ＴＥＳＴ", the characters after the NULL character are deleted and dovecot.sieve ends normally.
This is a sample of the data that we collected. Subject: =?ISO-2022-JP?B?GyRCI1QjRSNTI1QbKEIAGyRCI00jQSNJI0wbKEI=?= X-Spam-Score: 100.00% ↓ Subject: [SPAM] =?utf-8?b?77y077yl77yz77y0?= X-Spam-Score: 100.00%
-Environment ・OS CentOS release 6.5 (Final) x86_64
・Software Version dovecot-2.2.12 dovecot-2.2-pigeonhole-0.4.2
・Results from the "dovecot -n" command.
# 2.2.12: /etc/dovecot/dovecot.conf # OS: Linux 2.6.32-431.5.1.el6.x86_64 x86_64 CentOS release 6.5 (Final) disable_plaintext_auth = no lock_method = dotlock mail_fsync = always mail_gid = vmail mail_location = maildir:~/Maildir mail_nfs_index = yes mail_nfs_storage = yes mail_plugins = quota mail_temp_dir = /var/tmp mail_uid = vmail managesieve_notify_capability = mailto managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress
comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify
environment mailbox date ihave spamtest spamtestplus editheader mbox_write_locks = dotlock mmap_disable = yes passdb { driver = passwd } plugin { quota = maildir:User quota sieve = ~/Maildir/dovecot.sieve sieve_dir = ~/Maildir/sieve sieve_editheader_max_header_size = 1k sieve_editheader_protected = X-Verified sieve_extensions = +editheader +spamtest +spamtestplus sieve_max_actions = 250 sieve_max_redirects = 100 sieve_spamtest_max_value = 100.00 sieve_spamtest_status_header = X-Spam-Score: ([[:digit:]]+\.[[:digit:]]+)% sieve_spamtest_status_type = score sieve_user_log = /var/log/dovecot.sieve/%d/%u.log } postmaster_address = postmaster@example.jp protocols = pop3 imap service auth { unix_listener auth-userdb { group = vmail mode = 0600 user = vmail } } ssl_ca = </etc/pki/tls/certs/CA.crt ssl_cert = </etc/pki/tls/certs/example.jp.crt ssl_key = </etc/pki/tls/private/example.jp.key submission_host = 127.0.0.1:20025 userdb { args = /etc/dovecot/ldap/userdb.conf.ext driver = ldap } protocol lda { mail_plugins = quota sieve } protocol imap { mail_plugins = quota imap_quota passdb { args = /etc/dovecot/ldap/passdb.conf.ext driver = ldap } } protocol pop3 { passdb { args = /etc/dovecot/ldap/passdb.conf.ext driver = ldap } }
-Contents of the "dovecot.sieve" file user/Maildir/dovecot.sieve
require "fileinto"; require "mailbox"; require "envelope"; require "variables"; require "editheader"; require "spamtestplus"; require "relational"; require "enotify"; require "comparator-i;ascii-numeric";
if spamtest :percent :value "ge" :comparator "i;ascii-numeric" "80" { if exists "subject" { deleteheader :matches "subject" "*"; addheader "Subject" "[SPAM] ${1}"; } else { addheader "Subject" "[SPAM]"; } }
Please reply. Thank you.
--
Atsuko Tanaka DesigNET Inc. e-mail：tanaka@designet.co.jp
On 2.5.2014, at 11.27, Atsuko Tanaka <tanaka@designet.co.jp> wrote:
We have currently set dovecot.sieve to insert the text "[SPAM]" at the beginning of an e-mail's subject when it's X-Spam-Score is above 80%. After we set our system as stated the following errors occur:
When an e-mail's subject contains control characters like [Ctrl+V|^V], dovecot.sieve terminates with an error and an e-mail is not able to be sent. When a MIME encoded Subject like [ＴＥＳＴ^VＭＡＩＬ] is sent we're not able to edit the subject and dovecot ends with an error. .. Aside from [Ctrl + V] the following control charcters also cause errors: backspace Ctrl + A Ctrl + C Ctrl + [ Ctrl + X Ctrl + Y
When an e-mail's subject line contains a "\0" character, everything following the null character is deleted.
Is there a reason why mails contain these kind of control characters? Is it commonly used? And is it OK if Dovecot translates them to UTF-8 for the rewritten header, or would the subject have to stay ISO-2022-JP encoded?
Timo Sirainen wrote:
Is there a reason why mails contain these kind of control characters? Is it commonly used? And is it OK if Dovecot translates them to UTF-8 for the rewritten header, or would the subject have to stay ISO-2022-JP encoded?
Some spammers may like to core dump our servers :-)
Thank you for reply.
(2014/05/05 21:24), Timo Sirainen wrote:
Is there a reason why mails contain these kind of control characters? Is it commonly used? And is it OK if Dovecot translates them to UTF-8 for the rewritten header, or would the subject have to stay ISO-2022-JP encoded?
Not common, but it is present. Spammers may send. I'm in trouble in fact.
Atsuko Tanaka
We were able to solve the problem, "When a control character is included in the subject of an e-mail, dovecot exits with a fatal error" using the following information: 1. We added the following field to the sieve setting file: /etc/dovecot/conf.d/90-sieve.conf --------------------------------------------------------------------- sieve_editheader_rfc2822_check = yes --------------------------------------------------------------------- This is a switch for whether or not to check if a file is RFC2822 or not. When it's set to yes, it works the exact same as before changes were made. The default is yes. 2. When the sieve_editheader_rfc2822_check setting is set to no, we make sure not to check for RFC2822. Version: dovecot-2.2-pigeonhole-0.4.2 The patch is listed as below: --------------------------------------------------------------------- diff -Nur dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/plugins/editheader/cmd-addheader.c dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/plugins/editheader/cmd-addheader.c --- dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/plugins/editheader/cmd-addheader.c 2014-05-14 15:17:52.586774630 +0900 +++ dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/plugins/editheader/cmd-addheader.c 2014-05-14 15:22:12.536780572 +0900 @@ -281,7 +281,8 @@ return SIEVE_EXEC_OK; } - if ( !rfc2822_header_field_body_verify + if ( this_ext->svinst->chk_rfc2822 == TRUE && + !rfc2822_header_field_body_verify (str_c(value), str_len(value), TRUE, TRUE) ) { sieve_runtime_error(renv, NULL, "addheader action: " "specified value `%s' is invalid", diff -Nur dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/sieve-common.h dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/sieve-common.h --- dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/sieve-common.h 2014-05-14 15:17:52.593774606 +0900 +++ dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/sieve-common.h 2014-05-14 15:23:57.584775286 +0900 @@ -189,6 +189,9 @@ size_t max_script_size; unsigned int max_actions; unsigned int max_redirects; + + /* Check */ + bool chk_rfc2822; }; #endif /* __SIEVE_COMMON_H */ diff -Nur dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/sieve.c dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/sieve.c --- dovecot-2.2-pigeonhole-0.4.2_org/src/lib-sieve/sieve.c 2014-05-14 15:17:52.583774672 +0900 +++ dovecot-2.2-pigeonhole-0.4.2/src/lib-sieve/sieve.c 2014-05-14 15:19:39.628771207 +0900 @@ -51,6 +51,7 @@ size_t size_setting; const char *domain; pool_t pool; + bool bool_setting; /* Create Sieve engine instance */ pool = pool_alloconly_create("sieve", 8192); @@ -118,6 +119,15 @@ svinst->max_redirects = (unsigned int) uint_setting; } + /* Check RFC2822 from configuration */ + + svinst->chk_rfc2822 = TRUE; + + if (sieve_setting_get_bool_value + (svinst, "sieve_editheader_rfc2822_check", &bool_setting) ) { + svinst->chk_rfc2822 = bool_setting; + } + /* Initialize extensions */ if ( !sieve_extensions_init(svinst) ) { sieve_deinit(&svinst); ---------------------------------------------------------------------
1) When an e-mail's subject contains control characters like [Ctrl+V|^V], dovecot.sieve terminates with an error and an e-mail is not able to be sent. When a MIME encoded Subject like [ＴＥＳＴ^VＭＡＩＬ] is sent we're not able to edit the subject and dovecot ends with an error.
This is a sample of the data that was used in testing. Subject: =?ISO-2022-JP?B?GyRCI1QjRSNTI1QbKEIWGyRCI00jQSNJI0wbKEI=?= X-Spam-Score: 100.00% ↓ Subject: =?ISO-2022-JP?B?GyRCI1QjRSNTI1QbKEIWGyRCI00jQSNJI0wbKEI=?= X-Spam-Score: 100.00%
This is the log generated by the data above. ---------------------------------------------------------------------- sieve: info: started log at May 02 10:46:22. main script: line 14: error: addheader action: specified value `[SPAM] ＴＥＳＴ?・・' is invalid. ----------------------------------------------------------------------
Aside from [Ctrl + V] the following control charcters also cause errors: backspace Ctrl + A Ctrl + C Ctrl + [ Ctrl + X Ctrl + Y
Atsuko Tanaka
On 5/22/2014 7:28 AM, Atsuko Tanaka wrote:
We were able to solve the problem, "When a control character is included in the subject of an e-mail, dovecot exits with a fatal error" using the following information:
Did you try the latest versions? We made a few changes that should resolve this already.
Regards,
Stephan.
participants (4)
-
Atsuko Tanaka
-
Milan Cvetkovic
-
Stephan Bosch
-
Timo Sirainen