contrib/apparmor: Merge pasta and passt profiles, update rules

AppArmor resolves executable links before profile attachment rules
are evaluated, so, as long as pasta is installed as a link to passt,
there's no way to differentiate the two cases. Merge the two profiles
and leave a TODO note behind, explaining two possible ways forward.

Update the rules so that passt and pasta are actually usable, once
the profile is installed. Most required changes are related to
isolation and sandboxing features.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

2 files changed, 51 insertions, 88 deletions

diff --git a/contrib/apparmor/usr.bin.passt b/contrib/apparmor/usr.bin.passt
index a19fede..96b61ef 100644
--- a/contrib/apparmor/usr.bin.passt
+++ b/contrib/apparmor/usr.bin.passt
@@ -3,7 +3,10 @@
 # PASST - Plug A Simple Socket Transport
 #  for qemu/UNIX domain socket mode
 #
-# contrib/apparmor/usr.bin.passt - AppArmor profile example/template for passt
+# PASTA - Pack A Subtle Tap Abstraction
+#  for network namespace/tap device mode
+#
+# contrib/apparmor/usr.bin.passt - AppArmor profile for passt(1) and pasta(1)
 #
 # Copyright (c) 2022 Red Hat GmbH
 # Author: Stefano Brivio <sbrivio@redhat.com>
@@ -12,31 +15,29 @@ abi <abi/3.0>,
 
 include <tunables/global>
 
-/usr/bin/passt {
-  ### Alternatively: include <abstractions/base>
-  @{etc_ro}/ld.so.cache			r,
-  /{usr/,}lib{,32,64}/ld-*.so		r,
-  /{usr/,}lib{,32,64}/libc-*.so		mr,
-  /{usr/,}lib/@{multiarch}/ld-*.so	r,
-  /{usr/,}lib/@{multiarch}/libc-*.so	mr,
-  /dev/null 				rw,	# __daemon(), util.c
-  signal receive set=int peer=unconfined,
-  signal receive set=term peer=unconfined,
-  ###
+profile passt /usr/bin/passt{,.avx2} flags=(attach_disconnected) {
+  ### Common rules for passt and pasta
 
-  ### Alternatively: include <abstractions/nameservice>
+  include <abstractions/base>
+
+  # Alternatively: include <abstractions/nameservice>
   @{etc_ro}/resolv.conf			r,	# get_dns(), conf.c
-  ###
 
-  capability sys_admin,				# sandbox(), passt.c
-  capability setpcap,				# drop_caps(), util.c
+  capability net_bind_service,			# isolation.c, conf.c
+  capability setuid,
+  capability setgid,
+  capability sys_admin,
+  capability setpcap,
+  capability net_admin,
+  capability sys_ptrace,
 
-  mount		""	-> "/",			# sandbox(), passt.c
+  /					r,	# isolate_prefork(), isolation.c
+  mount		""	-> "/",
   mount		""	-> "/tmp/",
   pivot_root	"/tmp/" -> "/tmp/",
   umount	"/",
 
-  network netlink raw,				# netlink.c
+  network netlink raw,				# nl_sock_init_do(), netlink.c
 
   network inet stream,				# tcp.c
   network inet6 stream,
@@ -46,14 +47,42 @@ include <tunables/global>
 
   network unix stream,				# tap.c
 
-  network unix dgram,				# __openlog(), util.c
+  network unix dgram,				# __openlog(), log.c
 
-  ### Alternatively: include <abstractions/user-tmp>
+  # Alternatively: include <abstractions/user-tmp>
   owner /tmp/**				w,	# tap_sock_unix_init(), pcap(),
-						# write_pidfile()
-  ###
+						# write_pidfile(),
+						# logfile_init()
 
   owner @{HOME}/**			w,	# pcap(), write_pidfile()
 
   /usr/bin/passt.avx2			ix,	# arch_avx2_exec(), arch.c
+
+
+  ### Rules for pasta
+  ###
+  ### TODO: AppArmor doesn't give us the chance to attach a separate profile
+  ### depending on the executable symlink. That's possible with SELinux. Two
+  ### alternatives: implement that in AppArmor, or consider aa_change_hat(2).
+  ### With this, rules for passt(1) could be restricted significantly. Note that
+  ### the attach_disconnected flag is not needed for passt(1).
+
+  @{PROC}/net/tcp			r,	# procfs_scan_listen(), util.c
+  @{PROC}/net/tcp6			r,
+  @{PROC}/net/udp			r,
+  @{PROC}/net/udp6			r,
+
+  @{run}/user/@{uid}/netns/*		r,	# pasta_open_ns(), pasta.c
+
+  @{PROC}/[0-9]*/ns/net			r,	# pasta_wait_for_ns(),
+  @{PROC}/[0-9]*/ns/user		r,	# conf_pasta_ns()
+
+  /dev/net/tun				rw,	# tap_ns_tun(), tap.c
+
+  owner @{PROC}/@{pid}/gid_map		w,	# pasta_start_ns(), conf_ugid()
+  owner @{PROC}/@{pid}/setgroups	w,
+  owner @{PROC}/@{pid}/uid_map		rw,
+
+  owner @{PROC}/sys/net/ipv4/ping_group_range w, # pasta_spawn_cmd(), pasta.c
+  /{usr/,}bin/**			Ux,
 }
diff --git a/contrib/apparmor/usr.bin.pasta b/contrib/apparmor/usr.bin.pasta
deleted file mode 100644
index 844fcf3..0000000
--- a/contrib/apparmor/usr.bin.pasta
+++ /dev/null
@@ -1,66 +0,0 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
-#
-# PASTA - Pack A Subtle Tap Abstraction
-#  for network namespace/tap device mode
-#
-# contrib/apparmor/usr.bin.pasta - AppArmor profile example/template for pasta
-#
-# Copyright (c) 2022 Red Hat GmbH
-# Author: Stefano Brivio <sbrivio@redhat.com>
-
-abi <abi/3.0>,
-
-include <tunables/global>
-
-/usr/bin/pasta flags=(attach_disconnected) {
-  include <abstractions/base>			# Interactive shell
-  include <abstractions/nameservice>
-  include <abstractions/consoles>
-  include <abstractions/bash>
-  owner /proc/**/ns/user		r,
-  /					r,
-  capability sys_ptrace,			# bash
-  capability dac_read_search,
-  capability dac_override,
-  @{etc_ro}/**				r,
-  /usr/**				r,
-  /lib/**				r,
-  owner @{HOME}/**			rw,
-  owner /tmp/**				rw,
-
-  /proc/*/net/tcp			r,	# procfs_scan_listen(), util.c
-  /proc/*/net/tcp6			r,
-  /proc/*/net/udp			r,
-  /proc/*/net/udp6			r,
-
-  /dev/net/tun				rw,	# tap_ns_tun(), tap.c
-
-  capability net_admin,				# for network namespace only
-  capability setpcap,				# drop_caps(), util.c
-  capability sys_admin,				# sandbox(), passt.c
-
-  mount		""	-> "/",			# sandbox(), passt.c
-  mount		""	-> "/tmp/",
-  pivot_root	"/tmp/" -> "/tmp/",
-  umount	"/",
-
-  network netlink raw,				# netlink.c
-
-  network inet stream,				# tcp.c
-  network inet6 stream,
-
-  network inet dgram,				# udp.c
-  network inet6 dgram,
-
-  network unix stream,				# tap.c
-
-  network unix dgram,				# __openlog(), util.c
-
-  owner /proc/*/gid_map			w,	# pasta_setup_ns()
-  owner /proc/*/setgroups		w,
-  owner /proc/*/uid_map			w,
-  owner /proc/sys/net/ipv4/ping_group_range w,
-  /{usr/,}bin/**			mrix,	# spawning shell
-
-  /usr/bin/pasta.avx2			ix,	# arch_avx2_exec(), arch.c
-}