Public bug reported:

When setting a features-file in /etc/apparmor/apparmor.conf (and using policies 
for this feature-set) certain operations are DENIED, although they should be 
allowed.
This occurs for example when running an Ubuntu kernel with Debian Buster 
apparmor.

Steps for reproducing:
* Starting from a minimal Buster VM (apparmor 2.13.2-10)
* Install unbound (one example) - apparmor confinement works as expected
* Install a kernel from Ubuntu (tested with: 5.0.0-25.26 from disco and 
5.2.0-15.16 from eoan)
* Reboot - unbound fails to start - the following messages are in `dmesg`:

```
[    3.109740] audit: type=1400 audit(1567527034.644:9): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=516 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
[    3.113969] audit: type=1400 audit(1567527034.652:10): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=516 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
[    5.322119] audit: type=1400 audit(1567527036.856:21): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
[    5.324621] audit: type=1400 audit(1567527036.860:22): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
[    5.326335] audit: type=1400 audit(1567527036.860:23): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="inet6" sock_type="dgram" protocol=0 requested_mask="create" 
denied_mask="create"
```

The problem does not occur when:
* booting the corresponding mainline kernels (5.0.18 and 5.29)
* booting debian kernels (5.2.9-2 from testing+sid and 4.19.0-5-amd64 from 
buster)
* the features-file is changed to reflect the features present in Ubuntu kernels
* the features-file option is removed (commented out) in 
/etc/apparmor/apparmor.conf

Opening the bug against linux and not apparmor, because it looks to me like the 
issue might be in
the Ubuntu patches.

Glad to provide further information and help testing!

Thanks for all your great work!

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: apparmor

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https://bugs.launchpad.net/bugs/1842459

Title:
  apparmor abi-feature pinning not working with Disco and Eoan kernels

Status in linux package in Ubuntu:
  New

Bug description:
  When setting a features-file in /etc/apparmor/apparmor.conf (and using 
policies for this feature-set) certain operations are DENIED, although they 
should be allowed.
  This occurs for example when running an Ubuntu kernel with Debian Buster 
apparmor.

  Steps for reproducing:
  * Starting from a minimal Buster VM (apparmor 2.13.2-10)
  * Install unbound (one example) - apparmor confinement works as expected
  * Install a kernel from Ubuntu (tested with: 5.0.0-25.26 from disco and 
5.2.0-15.16 from eoan)
  * Reboot - unbound fails to start - the following messages are in `dmesg`:

  ```
  [    3.109740] audit: type=1400 audit(1567527034.644:9): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=516 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
  [    3.113969] audit: type=1400 audit(1567527034.652:10): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=516 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
  [    5.322119] audit: type=1400 audit(1567527036.856:21): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
  [    5.324621] audit: type=1400 audit(1567527036.860:22): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="unix" sock_type="stream" protocol=0 requested_mask="create" 
denied_mask="create" addr=none
  [    5.326335] audit: type=1400 audit(1567527036.860:23): apparmor="DENIED" 
operation="create" profile="/usr/sbin/unbound" pid=549 comm="unbound" 
family="inet6" sock_type="dgram" protocol=0 requested_mask="create" 
denied_mask="create"
  ```

  The problem does not occur when:
  * booting the corresponding mainline kernels (5.0.18 and 5.29)
  * booting debian kernels (5.2.9-2 from testing+sid and 4.19.0-5-amd64 from 
buster)
  * the features-file is changed to reflect the features present in Ubuntu 
kernels
  * the features-file option is removed (commented out) in 
/etc/apparmor/apparmor.conf

  Opening the bug against linux and not apparmor, because it looks to me like 
the issue might be in
  the Ubuntu patches.

  Glad to provide further information and help testing!

  Thanks for all your great work!

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