Re: Untaint $local_part, $domain and other variables

On 9/14/25 13:42, Jeremy Harris via Exim-users wrote:

> On 2025/09/14 6:09 PM, Emilio Augusto Lazo Zaia via Exim-users wrote:
>> I'm trying to implement a mechanism to notify a local recipient when a message addressed to them is denied by an ACL rule
>
> If a message has been denied, how will this transport be run?
>
> I think you have more issues than those arguments.

I did not explain sufficiently.

on check_rcpt_acl:

warn
     spf = fail
     condition = ${if match_domain{$domain}{+local_domains}{yes}{no}}
     set acl_m2 = spf_fail_notify

accept
     condition = ${if eq{$acl_m2}{spf_fail_notify}{yes}{no}}
     log_message = SPF FAIL - Notifying recipient $local_part@$domain

Router:

spf_fail:
     driver = accept
     condition = ${if eq{$acl_m2}{spf_fail_notify}{yes}{no}}
     transport = spf_fail_notif
     no_more

Actually, the email would not be "denied" by an ACL as I mentioned. Instead, it will only be tagged with the variable acl_m2 and then processed on transport through the script. This script will then discard the message and write a warning to the user (or write to a file to take other actions, such as notifying them once a day).

My only concern is with all the variables the transport must send to the script as arguments, since Exim refuses to use them because they are all *tainted*."


-- 
Emilio Augusto Lazo Zaia


-- 
Emilio Augusto Lazo Zaia

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