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Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set

From Mimi Zohar <zohar@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set
Date 2017-04-07 14:40 +0200
Message-ID <ttBlf-746-3@gated-at.bofh.it> (permalink)
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On Fri, 2017-04-07 at 10:17 +0100, David Howells wrote:
> Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> 
> > > Okay, fair enough.  I can stick in an OR with an IS_ENABLED on some IMA
> > > symbol.  CONFIG_IMA_KEXEC maybe?  And also require IMA be enabled?
> > 
> > Not quite, since as Dave pointed out, IMA is policy driven.  As a
> > policy is installed, we could set a flag.
> 
> Does such a flag exist as yet?

Not exactly what is needed.  There's a flag named ima_appraise, which
is used internally in IMA. A temporary flag is created, while
validating the rules.

	if (default_appraise_rules[i].func == POLICY_CHECK)
        	temp_ima_appraise |= IMA_APPRAISE_POLICY;

        if (!result && (entry->action == UNKNOWN))
                result = -EINVAL;
        else if (entry->func == MODULE_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_MODULES;
        else if (entry->func == FIRMWARE_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
        else if (entry->func == POLICY_CHECK)
                temp_ima_appraise |= IMA_APPRAISE_POLICY;

If the entire policy is valid,   ima_update_policy_flag() sets the ima_appraise flag.

        ima_appraise |= temp_ima_appraise;

From an IMA perspective, either a file hash or signature are valid,
but for this usage it must be a signature.  So in addition to testing
entry->func, above, entry->flags would need to be tested as well to
detect if IMA_DIGSIG_REQUIRED is set.

Mimi

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Thread

[PATCH 00/24] Kernel lockdown David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 24/24] Lock down module params that specify hardware  parameters (eg. ioport) David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 03/24] efi: Lock down the kernel if booted in secure boot  mode David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 20/24] bpf: Restrict kernel image access functions when the  kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
    Re: [PATCH 20/24] bpf: Restrict kernel image access functions when  the kernel is locked down Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2017-04-06 14:30 +0200
      Re: [PATCH 20/24] bpf: Restrict kernel image access functions when  the kernel is locked down Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-04-06 14:50 +0200
  [PATCH 12/24] PCI: Lock down BAR access when the kernel is locked  down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 15/24] asus-wmi: Restrict debugfs interface when the kernel  is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
    Re: [PATCH 15/24] asus-wmi: Restrict debugfs interface when the  kernel is locked down Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-04-07 12:30 +0200
      Re: [PATCH 15/24] asus-wmi: Restrict debugfs interface when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-07 15:00 +0200
        Re: [PATCH 15/24] asus-wmi: Restrict debugfs interface when the  kernel is locked down Andy Shevchenko <andy.shevchenko@gmail.com> - 2017-04-09 13:20 +0200
          Re: [PATCH 15/24] asus-wmi: Restrict debugfs interface when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-10 15:20 +0200
  [PATCH 02/24] Add the ability to lock down access to the running  kernel image David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 07/24] kexec: Disable at runtime if the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
    Re: [PATCH 07/24] kexec: Disable at runtime if the kernel is locked  down Dave Young <dyoung@redhat.com> - 2017-04-07 05:10 +0200
  [PATCH 08/24] Copy secure_boot flag in boot params across kexec  reboot David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 06/24] Add a sysrq option to exit secure boot mode David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 10/24] hibernate: Disable when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:20 +0200
  [PATCH 14/24] x86: Restrict MSR access when the kernel is locked  down David Howells <dhowells@redhat.com> - 2017-04-05 22:30 +0200
  [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:30 +0200
  [PATCH 11/24] uswsusp: Disable when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-05 22:30 +0200
    Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-06 01:40 +0200
      Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down Oliver Neukum <oneukum@suse.com> - 2017-04-06 08:50 +0200
        Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-06 11:30 +0200
          Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-06 22:20 +0200
            Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down Jiri Kosina <jikos@kernel.org> - 2017-04-06 22:30 +0200
              Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down poma <pomidorabelisima@gmail.com> - 2017-04-08 05:30 +0200
          Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-06 22:20 +0200
      Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down David Howells <dhowells@redhat.com> - 2017-04-06 09:00 +0200
        Re: [PATCH 11/24] uswsusp: Disable when the kernel is locked down "Rafael J. Wysocki" <rafael@kernel.org> - 2017-04-06 22:20 +0200
  [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set David Howells <dhowells@redhat.com> - 2017-04-05 22:30 +0200
    Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Dave Young <dyoung@redhat.com> - 2017-04-07 05:10 +0200
      Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-04-07 05:50 +0200
        Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Dave Young <dyoung@redhat.com> - 2017-04-07 08:20 +0200
          Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set David Howells <dhowells@redhat.com> - 2017-04-07 09:10 +0200
            Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Dave Young <dyoung@redhat.com> - 2017-04-07 09:50 +0200
              Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-04-07 10:30 +0200
                Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Dave Young <dyoung@redhat.com> - 2017-04-07 10:50 +0200
          Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-04-07 09:50 +0200
            Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Dave Young <dyoung@redhat.com> - 2017-04-07 10:10 +0200
        Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set David Howells <dhowells@redhat.com> - 2017-04-07 09:20 +0200
          Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-04-07 09:50 +0200
            Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set David Howells <dhowells@redhat.com> - 2017-04-07 11:20 +0200
              Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has  been set Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-04-07 14:40 +0200
                Re: [PATCH 09/24] kexec_file: Disable at runtime if securelevel has been set David Howells <dhowells@redhat.com> - 2017-04-10 15:30 +0200
  Re: [PATCH 00/24] Kernel lockdown "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2017-04-07 18:10 +0200
    Re: [PATCH 00/24] Kernel lockdown Justin Forbes <jmforbes@linuxtx.org> - 2017-04-07 18:40 +0200

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