Stubby is a DNS resolver that encrypts DNS queries and transmits them to
a resolver in a TLS channel. It therefore requires less permissions than
a traditionnal DNS resolver such as named or unbound (provided by module
"bind").
cf. https://dnsprivacy.org/wiki/display/DP/DNS+Privacy+Daemon+-+Stubby
This program is packaged for Arch Linux, Debian, etc.
DNS-over-TLS uses TCP port 853, which does not seem to conflict with
existing ports. Label it like other DNS ports.
init_dbus_chat(stubby_t) is required on systemd-based distributions
because stubby's service uses DynamicUser=yes [1]. Without this
statement, the following denials are reported by dbus:
type=USER_AVC msg=audit(1550007165.936:257): pid=274 uid=81
auid=4294967295 ses=4294967295 subj=system_u:system_r:system_dbusd_t
msg='avc: denied { send_msg } for msgtype=method_call
interface=org.freedesktop.DBus member=Hello
dest=org.freedesktop.DBus spid=649
scontext=system_u:system_r:stubby_t
tcontext=system_u:system_r:system_dbusd_t tclass=dbus permissive=1
exe="/usr/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
type=USER_AVC msg=audit(1550007165.939:258): pid=274 uid=81
auid=4294967295 ses=4294967295 subj=system_u:system_r:system_dbusd_t
msg='avc: denied { send_msg } for msgtype=method_call
interface=org.freedesktop.systemd1.Manager
member=LookupDynamicUserByUID dest=org.freedesktop.systemd1 spid=649
tpid=1 scontext=system_u:system_r:stubby_t
tcontext=system_u:system_r:init_t tclass=dbus permissive=1
exe="/usr/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
type=USER_AVC msg=audit(1550007165.939:259): pid=274 uid=81
auid=4294967295 ses=4294967295 subj=system_u:system_r:system_dbusd_t
msg='avc: denied { send_msg } for msgtype=method_return dest=:1.39
spid=1 tpid=649 scontext=system_u:system_r:init_t
tcontext=system_u:system_r:stubby_t tclass=dbus permissive=1
exe="/usr/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
[1] https://github.com/getdnsapi/stubby/blob/v0.2.5/systemd/stubby.service#L8
Nicolas Iooss