path: root/postfix/postfix.sh

#!/bin/sh
#
# /etc/local-COMMON/postfix/postfix.sh
# Copyright 2002-2010,2013-2016,2020 Jonas Smedegaard <dr@jones.dk>
#
# Auto-tweak plain installed postfix Debian package
#
# TODO:
#  * Implement stuff from here: http://www.wsrcc.com/spam/
#  * Implement stuff from here: http://www.muine.org/~hoang/postfix.html
#  * Implement stuff from here: http://jimsun.linxnet.com/misc/postfix-anti-UCE.txt
#  * Figure out a way to use chroot jail for TLS stuff.
#  * Use https://www.dnswl.org/

set -e

# Let's standardize sort
export LC_ALL=C

warn()  {
    echo >&2 "Warning: $1"
}

exit1() {
    echo >&2 "Error: $1"
    echo >&2 "Exiting..."
    exit 1
}

FORCE=${FORCE:-}

REDPILL=${REDPILL:-REDPILL}
REALM=${REALM:-ORG}

TLS_CERT=${TLS_CERT:-/etc/ssl/certs/postfix.pem}
TLS_KEY=${TLS_KEY:-/etc/ssl/private/postfix.pem}

# TODO: maybe use AMaViS default of 20 (and instead tune spamassassin)
# <https://www.ijs.si/software/amavisd/amavisd-new-docs.html#max_requests>
AMAVIS_MAXPROC=${AMAVIS_MAXPROC:-2}

# TODO: check if DKIMPROXY_MAXPROC_IN should be handled too
#DKIMPROXY_MAXPROC_IN=5
DKIMPROXY_MAXPROC_OUT=5

# resolve redpill config paths
realmsdir="/etc/local-$REDPILL"
thisrealm=$(cat "/etc/local-$REALM/realm" || dnsdomainname | tr '[:lower:]' '[:upper:]')
if ! [ -d "$realmsdir" ]; then
    warn "Realms directory \"$realmsdir\" does not exist."
fi
catfilefromownrealm() {
    set -e
    file=$1
    [ -d "$realmsdir" ] || exit 0

    cat "$realmsdir/$thisrealm/$file"
}
catallfilesfromotherrealms() {
    set -e
    file=$1
    [ -d "$realmsdir" ] || exit 0
    [ -f "$realmsdir/realms" ] || exit 0

    realms=$(sed 's/#.*//' < "$realmsdir/realms")

    for realm in $realms; do
        if [ "$thisrealm" != "$realm" ]; then
            cat "$realmsdir/$realm/$file"
        fi
    done
}
catfirstfile() {
    set -e
    file=$1
    context=${2:-postfix}
    configdir=
    for dir in /etc/local "/etc/local-$REALM" "/etc/local-$REDPILL" /etc/local-COMMON; do
        if [ -d "$dir/$context" ] && [ -f "$dir/$context/$file" ]; then
            configdir="$dir/$context"
            break
        fi
    done
    if [ -z "$configdir" ]; then
        exit1 "ERROR: file \"$file\" not found."
    fi
    cat "$configdir/$file"
}

# TODO: support trailing comment.
getperlvarfromfile() {
    set -e
    var=$1
    default=$2
    file=$3
    context=${4:-postfix}
    catfirstfile "$file" "$context" \
        | var=$var default=$default perl -n \
        -e '/^\$$ENV{"var"}\h*=\h*(\d+)/ and $s=$1; END {print length($s) ? $s : $ENV{"default"}}'
}

getlinesfromfile() {
    set -e
    param=$1
    shift
    replacements=
    for subparam in "$@"; do
        case "$subparam" in
            *=)
            oldparam=$(echo "$subparam" | awk -F= '{print $1}')
            replacements="$replacements;s/,*[^,]*${oldparam}[^,]*,*/,/"
            continue
            ;;
            *=*=*)
            oldparam=$(echo "$subparam" | awk -F= '{print $1}')
            newparam=$(echo "$subparam" | awk -F= '{print $2}')
            newparamfile=$(echo "$subparam" | awk -F= '{print $3}')
            ;;
            *)
            oldparam=$subparam
            newparam=$subparam
            newparamfile=$subparam
            ;;
        esac
        newparamvalues=$(getlinesfromfile "$newparamfile" | sed -e 's/.*=[ ]*//' -e 's/,/ /g')
        newstring=
        for newparamvalue in $newparamvalues; do
            newstring="${newstring}$newparam $newparamvalue,"
        done
        replacements="$replacements;s/$oldparam/$newstring/"
    done
    printf "%s = " "$param"
    catfirstfile "$param" | sed 's/#.*//' | tr '\n' ',' | sed -e 's/^[,     ]*//;s/[,   ]\+/,/g' -e 's/\^/ /g' -e "s/,\$//$replacements"
}

#postgrey=
#if [ -x /usr/sbin/postgrey ]; then
#   # FIXME: Use this somehow, and only warn below
#   postgrey=1
#else
#   exit1 "ERROR: Greylisting support (Debian package postgrey) missing."
#fi
dovecot=
dovecot_lmtp=
dovecot_deliver=
if [ -x /usr/sbin/dovecot ]; then
    dovecot=1
    if [ -x /usr/lib/dovecot/lmtp ]; then
        dovecot_lmtp=1
    elif [ -x /usr/lib/dovecot/deliver ]; then
        warn "Dovecot LMTP missing - (Debian package dovecot-lmtp)."
        dovecot_deliver=1
    else
        warn "Dovecot deliver missing."
    fi
else
    warn "Dovecot missing - (Debian package dovecot-core or dovecot)."
fi
tls_cert=
if [ -f "$TLS_CERT" ] && [ -f "$TLS_KEY" ]; then
    tls_cert=1
else
    warn "No TLS - requires certificate \"$TLS_CERT\" and key \"$TLS_KEY\"."
fi
# TODO: enable only on systems with user accounts
submission=1
# TODO: check that dovecot SASL is configured
sasl_inbound=
if [ -n "$tls_cert" ] && [ -n "$dovecot" ] && [ -n "$submission" ]; then
    sasl_inbound=1
else
    warn "No inbound SASL authentication - requires TLS encryption and Dovecot."
fi
amavis=
if [ -x /usr/sbin/amavisd ] || [ -x /usr/sbin/amavisd-new ]; then
    amavis=1
else
    warn "AMaViS missing (Debian package amavisd-new)."
fi
dkimproxy=
if [ -x /usr/sbin/dkimproxy.in ]; then
    if [ "1" = "$amavis" ]; then
        dkimproxy=1
    else
        warn "No DKIM/Domainkey - requires DKIMproxy and AMaViS."
    fi
else
    warn "DKIMproxy missing (Debian package dkimproxy)."
fi

confdir=/etc/postfix

_postconf() {
    postconf -c "$tempdir" "$1" "$(echo "$2" | tr '\n' ' ')"
}

postmapfiles=

tempdir=$(mktemp -td postfix.XXXXXX)
cp -a -t "$tempdir" "$confdir"/*

# Inspired by D. J. Bernstein: http://cr.yp.to/smtp/greeting.html
_postconf -e smtpd_banner="\$myhostname NO UCE ESMTP \$mail_name (Debian/GNU)"

# Some badly configured setup use hostname instead of FQDN
# Disable completely: Effective, but hurts executive type guys using windows servers... :-(
#if _postconf myhostname | grep -q '\.'; then
#   _postconf -e smtpd_helo_required=yes
#fi
_postconf -e smtpd_helo_required=no
_postconf -e "$(getlinesfromfile permit_mx_backup_networks)"
_postconf -e maps_rbl_domains=
_postconf -e "$(getlinesfromfile smtpd_client_restrictions reject_rhsbl_client)"
_postconf -e "$(getlinesfromfile smtpd_helo_restrictions)"
_postconf -e "$(getlinesfromfile smtpd_sender_restrictions reject_rhsbl_sender ${dkimproxy:-sender_access_regex=})"
_postconf -e "$(getlinesfromfile smtpd_recipient_restrictions reject_maps_rbl=reject_rbl_client=maps_rbl_domains)"
_postconf -e "$(getlinesfromfile smtpd_data_restrictions)"

# FIXME: clear only specific line (not whole file) when dkimproxy unused
if [ -f "$tempdir/sender_access_regex" ]; then
    if [ -n "$dkimproxy" ]; then
        grep -q -F '/^/  FILTER dkimsign:[127.0.0.1]:10026' "$tempdir/sender_access_regex" \
        || echo '/^/  FILTER dkimsign:[127.0.0.1]:10026' >> "$tempdir/sender_access_regex"
    else
        if grep -q -F '/^/  FILTER dkimsign:[127.0.0.1]:10026' "$tempdir/sender_access_regex"; then
            echo "echo '' > \"$confdir/sender_access_regex\"" >> "$tempdir/COMMANDS"
            rm "$tempdir/sender_access_regex"
        fi
    fi
    postmapfiles="$postmapfiles sender_access_regex"
fi

# Support exceptions to default response
# (Day Old Bread (dob) lists need to reject only temporarily)
_postconf -e rbl_reply_maps="hash:$confdir/rbl_reply_map"
sed 's/#.*//' \
    < /etc/local-COMMON/postfix/rbl_reply_map \
    > "$tempdir/rbl_reply_map"
postmapfiles="$postmapfiles rbl_reply_map"

# Verify senders of common suspicious and known verifiable domains
# (exclude verification of postmaster@ to not verify verification probes)
# (add own domains before peers for (rare) cases of duplicates)
# FIXME: somehow do this step only if enabled in smtpd_sender_restrictions
# TODO: Properly implement exception exclusion like yahoo (which does not want to be checked any longer!)
grep -v yahoo \
    < /etc/local-COMMON/postfix/maildomains \
    | sort \
    | sed 's/$/ reject_unverified_sender/' \
    > "$tempdir/sender_access"
( catfilefromownrealm maildomains | sort; catallfilesfromotherrealms maildomains | sort ) \
    | sed 's/\(.*\)$/postmaster@\1  permit\n\1  reject_unverified_sender/' \
    >> "$tempdir/sender_access"
[ ! -f "$tempdir/sender_access.addon" ] || cat "$tempdir/sender_access.addon" \
    >> "$tempdir/sender_access"
postmapfiles="$postmapfiles sender_access"
_postconf -e unverified_sender_reject_code=550

# Trust recipient verification too
_postconf -e unverified_recipient_reject_code=550

if [ -n "$dovecot_lmtp" ]; then
    _postconf -e mailbox_transport=lmtp:unix:private/dovecot-lmtp
    _postconf -X mailbox_command
elif [ -n "$dovecot_deliver" ]; then
    _postconf -X mailbox_transport
    _postconf -e mailbox_command=/usr/lib/dovecot/deliver
else
    _postconf -X mailbox_transport
    _postconf -X mailbox_command
fi

# outbound opportunistic encryption
_postconf -e smtp_tls_security_level=may
if [ -n "$tls_cert" ]; then
    _postconf -e smtp_tls_cert_file="$TLS_CERT"
    _postconf -e smtp_tls_key_file="$TLS_KEY"
else
    _postconf -X smtp_tls_cert_file
    _postconf -X smtp_tls_key_file
fi
_postconf -e smtp_tls_loglevel=1

# enforce TLS trust path towards peers
catallfilesfromotherrealms mailhost | sort \
    | sed 's/^/[/;s/$/]:submission  secure/' \
    > "$tempdir/tls_policy"
[ ! -f "$tempdir/tls_policy.addon" ] || cat "$tempdir/tls_policy.addon" \
    >> "$tempdir/tls_policy"
postmapfiles="$postmapfiles tls_policy"
_postconf -e smtp_tls_policy_maps="hash:$confdir/tls_policy"

# inbound opportunistic encryption
if [ -n "$tls_cert" ]; then
    _postconf -e smtpd_tls_security_level=may
    _postconf -e smtpd_tls_cert_file="$TLS_CERT"
    _postconf -e smtpd_tls_key_file="$TLS_KEY"
    _postconf -e smtpd_tls_loglevel=1
    _postconf -e smtpd_tls_auth_only=yes
    _postconf -e smtpd_tls_received_header=yes
else
    _postconf -e smtpd_tls_security_level=none
    _postconf -X smtpd_tls_cert_file
    _postconf -X smtpd_tls_key_file
    _postconf -X smtpd_tls_loglevel
    _postconf -X smtpd_tls_auth_only
    _postconf -X smtpd_tls_received_header
fi
# Avoid smtpd_tls_CApath or smtpd_tls_CAfile to trick outlook.com
# See <http://postfix.1071664.n5.nabble.com/Problems-with-incoming-mails-from-outlook-com-td78356.html>
_postconf -X smtpd_tls_CApath
_postconf -X smtpd_tls_CAfile

# obsolete TLS-related settings
_postconf -X smtpd_use_tls
_postconf -X smtp_tls_CApath
_postconf -X lmtp_tls_CApath
_postconf -X smtp_tls_CAfile
_postconf -X lmtp_tls_CAfile
_postconf -X smtpd_tls_ask_ccert
_postconf -X smtp_tls_note_starttls_offer
_postconf -X smtpd_tls_session_cache_database
_postconf -X smtpd_tls_session_cache_timeout
_postconf -X smtp_tls_session_cache_database
_postconf -X tls_random_exchange_name
_postconf -X tls_random_source

# submission
# <http://www.postfix.org/SASL_README.html>
# <https://doc.dovecot.org/configuration_manual/howto/postfix_and_dovecot_sasl/#using-sasl-with-postfix-submission-port>
if [ -n "$submission" ]; then
    _postconf -Me submission/inet="
submission inet n   -   y   -   -   smtpd
    -o syslog_name=postfix/\$service_name
    -o smtpd_tls_security_level=encrypt
"
    _postconf -Me smtps/inet="
smtps inet  n   -   y   -   -   smtpd
    -o syslog_name=postfix/\$service_name
    -o smtpd_tls_wrappermode=yes
    -o smtpd_sasl_auth_enable=yes
"
    if [ -n "$sasl_inbound" ]; then
        _postconf -Pe submission/inet/smtpd_sasl_auth_enable=yes
        _postconf -Pe smtps/inet/smtpd_sasl_auth_enable=yes
    else
        _postconf -PX submission/inet/smtpd_sasl_auth_enable
        _postconf -PX smtps/inet/smtpd_sasl_auth_enable
    fi
else
    _postconf -MX submission/inet
    _postconf -MX smtps/inet
fi
if [ -n "$sasl_inbound" ]; then
    _postconf -e smtpd_sasl_local_domain=\$mydomain
    _postconf -e smtpd_sasl_type=dovecot
    _postconf -e smtpd_sasl_path=private/auth
    _postconf -e broken_sasl_auth_clients=yes
else
    _postconf -X smtpd_sasl_local_domain
    _postconf -X smtpd_sasl_type
    _postconf -X smtpd_sasl_path
    _postconf -X broken_sasl_auth_clients
fi

# obsolete SASL-related settings
_postconf -X smtpd_sasl_auth_enable
_postconf -X smtpd_sasl_security_options

if [ -n "$amavis" ]; then
    amavis_maxproc=$(getperlvarfromfile max_servers "$AMAVIS_MAXPROC" amavisd.conf.addon amavis)
    _postconf -Me amavisfeed/unix="
amavisfeed unix -   -   n   -   $amavis_maxproc lmtp
    -o lmtp_data_done_timeout=1200s
    -o lmtp_send_xforward_command=yes
    -o disable_dns_lookups=yes
    -o max_use=$amavis_maxproc
"
    _postconf -Me 127.0.0.1:10025/inet='
127.0.0.1:10025 inet n  -   n   -   -   smtpd
    -o content_filter=
    -o local_recipient_maps=
    -o relay_recipient_maps=
    -o smtpd_restriction_classes=
    -o smtpd_delay_reject=no
    -o smtpd_client_restrictions=permit_mynetworks,reject
    -o smtpd_helo_restrictions=
    -o smtpd_sender_restrictions=
    -o smtpd_recipient_restrictions=permit_mynetworks,reject
    -o smtpd_data_restrictions=reject_unauth_pipelining
    -o smtpd_end_of_data_restrictions=
    -o mynetworks=127.0.0.0/8
    -o smtpd_error_sleep_time=0
    -o smtpd_soft_error_limit=1001
    -o smtpd_hard_error_limit=1000
    -o smtpd_client_connection_count_limit=0
    -o smtpd_client_connection_rate_limit=0
    -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks,no_milters
'
    _postconf -e receive_override_options=no_address_mappings
    if [ -n "$dkimproxy" ]; then
        _postconf -e content_filter='amavisfeed:[127.0.0.1]:10028'
        _postconf -Pe pickup/fifo/content_filter='dkimsign:127.0.0.1:10028'
        if [ -n "$submission" ]; then
            _postconf -Pe submission/inet/content_filter='dkimsign:[127.0.0.1]:10028'
            _postconf -Pe smtps/inet/content_filter='dkimsign:[127.0.0.1]:10028'
        fi
        # FIXME: supersede DKIMPROXY_MAXPROC_OUT from /etc/default/dkimproxy
        _postconf -Me dkimsign/unix="
dkimsign unix   -   -   n   -   $DKIMPROXY_MAXPROC_OUT  smtp
    -o smtp_send_xforward_command=yes
    -o smtp_discard_ehlo_keywords=8bitmime,starttls
"
        _postconf -Me 127.0.0.1:10029/inet='
127.0.0.1:10029 inet n  -   n   -   -   smtpd
    -o content_filter=
    -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks,no_milters
    -o smtpd_helo_restrictions=
    -o smtpd_client_restrictions=
    -o smtpd_sender_restrictions=
    -o smtpd_recipient_restrictions=permit_mynetworks,reject
    -o mynetworks=127.0.0.0/8
    -o smtpd_authorized_xforward_hosts=127.0.0.0/8
'
    else
        _postconf -MX dkimsign/unix
        _postconf -MX 127.0.0.1:10029/inet
        _postconf -e content_filter='amavisfeed:[127.0.0.1]:10024'
        _postconf -PX pickup/fifo/content_filter
        if [ -n "$submission" ]; then
            _postconf -PX submission/inet/content_filter
            _postconf -PX smtps/inet/content_filter
        fi
    fi
else
    _postconf -MX amavisfeed/unix
    _postconf -MX 127.0.0.1:10025/inet
    _postconf -X content_filter
    _postconf -X receive_override_options
fi

# obsolete settings
_postconf -X max_use
_postconf -MX smtp-amavis/unix

diff -ruNw "$confdir" "$tempdir" || if [ $? -gt 1 ]; then exit $?; else needs_reload=1; fi

if [ "1" = "$FORCE" ]; then
    do_update=y
elif [ "1" = "$needs_reload" ]; then
    printf 'Above is the intended changes. OK to update (y/N)? '
    read -r do_update
fi
case $do_update in
    y|Y)
    if [ -f "$tempdir/COMMANDS" ]; then
        sh -s < "$tempdir/COMMANDS"
    fi
    rm -f "$tempdir/COMMANDS"

    diff -q "$confdir/master.cf" "$tempdir/master.cf" || if [ $? -gt 1 ]; then exit $?; else needs_restart=1; fi

    cp -a -f -t "$confdir" "$tempdir"/*
    rm -rf "$tempdir"

    for file in $postmapfiles; do
        postmap "$confdir/$file"
    done

    if [ "1" = "$needs_restart" ]; then
        service postfix restart
    else
        service postfix force-reload
    fi

    if [ "1" = "$needs_reload" ]; then
        echo >&2 "Changes applied!"
    fi
    ;;
    *)
    if [ "1" = "$needs_reload" ]; then
        exit1 "Aborted!"
    fi
    ;;
esac

if [ "1" != "$needs_reload" ]; then
    echo >&2 "No changes needed!"
fi

# Based on this: http://jimsun.linxnet.com/misc/postfix-anti-UCE.txt
# Support for trusted MX backup networks added
# PCRE stuff avoided, as PCRE is only optional on newest Debian packages
# RBLs replaced with those recommended by http://www.antispews.org/
# spam filter based on these: http://www.postfix.org/FILTER_README.html
#   https://www.ijs.si/software/amavisd/amavisd-new-docs.html
# TLS based on this: http://www.postfix.org/TLS_README.html

# Here's a convenient overview of different blackholes:
#   http://rbls.org/