[Dovecot] When the subject portion of an e-mail contains a control character, dovecot.sieve terminates unexpectatedly.

[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