Re: [PATCH] apparmor: support finer-grained ptrace checks

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On 09/22/2017 04:55 PM, Jim Fehlig wrote:
On 09/22/2017 03:25 PM, Jamie Strandboge wrote:
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},

Yes, this is what I have on the test system, where I've been editing the profiles directly. I'm at a loss to explain why it works. I.e. why I can start confined domains with the rule, but can't without it.

Duh. With the bogus rule the profile fails to parse and thus is not loaded.

Regards,
Jim

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