[Bug 1918410] [NEW] isc-dhcp-client denied by apparmor

[Anisse Astier]

Public bug reported:

Hi, I get weird errors in the audit log, seeing dhclient is being denied
reading its comm or the comm of one of its tasks:


[1383307.827378] audit: type=1400 audit(1615367094.054:162): apparmor="DENIED" operation="open" profile="/{,usr/}sbin/dhclient" name="/proc/1095210/task/1095213/comm" pid=1095210 comm="dhclient" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0

This might or might not be linked with the fact that I can't get an IPv4
on this interface. Note that it happened to other, see this comment:

https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/1413232/comments/8

Or even an article recommending disabling apparmor for dhclient(!):
https://blog.anthony-jacob.com/perte-dip-v4-sous-ubuntu-20-04-apparmor-et-dhclient/


As I said, I'm not sure this is the root cause of the lack of IPv4 renewal, because running it manually *does* succeed in getting an IP. And running it in strace shows the EACCES failure:

[pid 1095210] openat(AT_FDCWD, "/proc/self/task/1095211/comm", O_RDWRstrace: Process 1095211 attached
) = -1 EACCES (Permission non accordée)

** Affects: isc-dhcp (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1918410

Title:
  isc-dhcp-client denied by apparmor

Status in isc-dhcp package in Ubuntu:
  New

Bug description:
  Hi, I get weird errors in the audit log, seeing dhclient is being
  denied reading its comm or the comm of one of its tasks:

  
  [1383307.827378] audit: type=1400 audit(1615367094.054:162): apparmor="DENIED" operation="open" profile="/{,usr/}sbin/dhclient" name="/proc/1095210/task/1095213/comm" pid=1095210 comm="dhclient" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0

  This might or might not be linked with the fact that I can't get an
  IPv4 on this interface. Note that it happened to other, see this
  comment:

  https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/1413232/comments/8

  Or even an article recommending disabling apparmor for dhclient(!):
  https://blog.anthony-jacob.com/perte-dip-v4-sous-ubuntu-20-04-apparmor-et-dhclient/

  
  As I said, I'm not sure this is the root cause of the lack of IPv4 renewal, because running it manually *does* succeed in getting an IP. And running it in strace shows the EACCES failure:

  [pid 1095210] openat(AT_FDCWD, "/proc/self/task/1095211/comm", O_RDWRstrace: Process 1095211 attached
  ) = -1 EACCES (Permission non accordée)

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