selinux-refpolicy/policy/modules/services/stubby.fc
Nicolas Iooss 919c889b7d
Add policy for stubby DNS resolver
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
2019-02-17 22:16:33 +01:00

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/etc/stubby(/.*)? -- gen_context(system_u:object_r:stubby_etc_t,s0)
/usr/bin/stubby -- gen_context(system_u:object_r:stubby_exec_t,s0)
/usr/lib/systemd/system/stubby.*\.service -- gen_context(system_u:object_r:stubby_unit_t,s0)