[PATCH] apparmor: Fixes for new user namespace detaching procedure

[PATCH] apparmor: Fixes for new user namespace detaching procedure

[Stefano Brivio]

Commit 7bf1595c9242 ("isolation: Don't create our userns as nobody")
changed the procedure user namespaces are detached, also for passt,
and adds unconditional setting of UID and GID maps.

This needs AppArmor adjustments:

- rules to access gid_map, uid_map, and setgroups entries in procfs
  now need to be enabled for passt as well, not just for pasta: move
  them to the passt abstraction (which is included from the pasta
  abstraction)

- we now need to open a user namespace originally detached by a
  separate holder process, which requires us to open procfs entries
  that are disconnected (from an AppArmor perspective) from the
  original namespace: add the attach_disconnected flag to the profile
  for passt as well (this was already the case for pasta).

  This isn't ideal but there doesn't seem any way around it: opening
  the namespace from the holder process itself doesn't help either.

  We'll need to add this flag also in passt subprofiles for
  guestfs-tools (maintained in Debian) and libvirtd (which only
  applies when guests are started as root for the moment, maintained
  by libvirt upstream).

Reported-by: Michal Humpula <bts@hudrydum.cz>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1149683
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 contrib/apparmor/abstractions/passt | 4 +++-
 contrib/apparmor/abstractions/pasta | 4 ----
 contrib/apparmor/usr.bin.passt      | 2 +-
 3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/contrib/apparmor/abstractions/passt b/contrib/apparmor/abstractions/passt
index f4570c1..0aeb19d 100644
--- a/contrib/apparmor/abstractions/passt
+++ b/contrib/apparmor/abstractions/passt
@@ -34,7 +34,9 @@
   pivot_root	"/tmp/" -> "/tmp/",
   umount	"/",
 
-  owner @{PROC}/@{pid}/uid_map		r,	# conf_ugid()
+  owner @{PROC}/@{pid}/gid_map		w,	# make_ugid_map()
+  owner @{PROC}/@{pid}/setgroups	w,
+  owner @{PROC}/@{pid}/uid_map		rw,
 
   @{PROC}/sys/net/ipv4/ip_local_port_range r,	# fwd_probe_ephemeral()
 
diff --git a/contrib/apparmor/abstractions/pasta b/contrib/apparmor/abstractions/pasta
index 251d4a2..89fa427 100644
--- a/contrib/apparmor/abstractions/pasta
+++ b/contrib/apparmor/abstractions/pasta
@@ -35,10 +35,6 @@
 
   /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.passt b/contrib/apparmor/usr.bin.passt
index da49e37..ccc2ea9 100644
--- a/contrib/apparmor/usr.bin.passt
+++ b/contrib/apparmor/usr.bin.passt
@@ -15,7 +15,7 @@ abi <abi/4.0>,
 
 include <tunables/global>
 
-profile passt /usr/bin/passt{,.avx2} {
+profile passt /usr/bin/passt{,.avx2} flags=(attach_disconnected) {
   include <abstractions/passt>
 
   include <abstractions/user-tmp>		# tap_sock_unix_open(),
-- 
2.43.0