Re: [libvirt] [PATCH] apparmor: support finer-grained ptrace checks
On Fri, 2017-09-22 at 15:04 -0600, Jim Fehlig wrote:
Using kernel 4.13, apparmor 2.11, and the current libvirt.git profiles,
simply
starting libvirtd results in the following denial
type=AVC msg=audit(1506112085.645:954): apparmor="DENIED"
operation="ptrace"
profile="/usr/sbin/libvirtd" pid=6984 comm="libvirtd"
requested_mask="trace"
denied_mask="trace" peer="unconfined"
Adding 'ptrace (trace) peer=unconfined,' allows starting libvirtd with no
denials. But this rule is not enough to start unconfined domains, where I see
the following denial
This is fine for the libvirtd profile (not libvirt-qemu/libvirt-lxc of course).
I'm curious what libvirtd is trying to trace...
type=AVC msg=audit(1506112301.227:1112): apparmor="DENIED"
operation="ptrace"
profile="/usr/sbin/libvirtd" pid=7498 comm="libvirtd"
requested_mask="trace"
denied_mask="trace" peer="/usr/sbin/libvirtd"
Adding 'ptrace (trace) peer=/usr/sbin/libvirtd,' allows starting unconfined
domains. But this is still not enough to start confined domains, where I see
the
following denials
This is fine for the libvirtd profile (not libvirt-qemu/libvirt-lxc of course).
I suspect this is for libvirtd tracing things it launches.
type=AVC msg=audit(1506112631.408:1312): apparmor="DENIED"
operation="open"
profile="virt-aa-helper" name="/etc/libnl/classid" pid=8283
comm="virt-aa-helper" requested_mask="r" denied_mask="r"
fsuid=0 ouid=0
type=AVC msg=audit(1506112631.530:1319): apparmor="DENIED"
operation="open"
profile="virt-aa-helper" name="/etc/libnl/classid" pid=8289
comm="virt-aa-helper" requested_mask="r" denied_mask="r"
fsuid=0 ouid=0
type=AVC msg=audit(1506112632.186:1324): apparmor="DENIED"
operation="ptrace"
profile="/usr/sbin/libvirtd" pid=8342 comm="libvirtd"
requested_mask="trace"
denied_mask="trace"
peer="libvirt-66154842-e926-4f92-92f0-1c1bf61dd1ff"
Finally, adding 'ptrace (trace) peer=(label=@{profile_name}),' allows
starting
confined domains.
This rule isn't right and doesn't parse (apparmor 2.11.0):
$ apparmor_parser -QTK ./apparmor.profile
AppArmor parser error for ./apparmor.profile in ./apparmor.profile at line 6:
syntax error, unexpected TOK_CONDLISTID, expecting TOK_CONDID or TOK_END_OF_RULE
I suspect you intended:
ptrace (trace) peer=@{profile_name},
but the denial you posted is the profile for libvirtd, so @{profile_name}
expands to "/usr/sbin/libvirtd", which the rule I just gave is the same as the
second rule above.
The peer in the denial is peer="libvirt-66154842-e926-4f92-92f0-1c1bf61dd1ff",
so the rule you want is:
ptrace (trace) peer=libvirt-*,
This should allow libvirtd to ptrace either qemu or libvirt-lxc guests.
--
Jamie Strandboge | http://www.canonical.com
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