** Description changed:
SRU Justification:
==================
[Impact]
* Currently the kernel module appended signature is verified twice
(finit_module) - once by the module_sig_check() and again by IMA.
* To prevent this the powerpc secure boot rules define an IMA
architecture specific policy rule only if CONFIG_MODULE_SIG_FORCE is not
enabled.
* But this doesn't take the ability into account of enabling
"sig_enforce" at the boot command line (module.sig_enforce=1).
* Including the IMA module appraise rule results in failing the
finit_module syscall, unless the module signing public key is loaded
onto the IMA keyring.
* This patch fixes secure boot policy rules to be based on
CONFIG_MODULE_SIG instead.
[Fix]
* fa4f3f56ccd28ac031ab275e673ed4098855fed4 fa4f3f56ccd2 "powerpc/ima:
Fix secure boot rules in ima arch policy"
[Test Case]
* Perform a secure boot on a powerpc system with 'module.sig_enforce=1'
set at the boot command.
* If the IMA module appraise rule is included, the finit_module syscall
will fail (unless the module signing public key got loaded onto the IMA
keyring) without having the patch in place.
- * The verificatiob needs to be done by the IBM Power team.
+ * The verification needs to be done by the IBM Power team.
[Regression Potential]
* There is (always) a certain regression risk with having code changes,
especially in the secure boot area.
* But this patch is limited to the powerpc platform and will not affect
any other architecture.
* It got discussed at
https://lore.kernel.org/r/[email protected]
- before it became finally upstream accepted with kernel 5.7-rc7.
+ before it became finally upstream accepted with kernel 5.7-rc7.
* The secure boot code itself wasn't really touched, rather than it's basis
for execution.
- The IMA policy rule for module appraisal is now added only if
'CONFIG_MODULE_SIG' is not enabled (instead of CONFIG_MODULE_SIG_FORCE).
- Hence the change is very limited and straightforward.
+ The IMA policy rule for module appraisal is now added only if
'CONFIG_MODULE_SIG' is not enabled (instead of CONFIG_MODULE_SIG_FORCE).
+ Hence the change is very limited and straightforward.
[Other]
* Since the patch got upstream with 5.7-rc7, it is already in groovy, hence
this SRU is for focal only.
__________
== Comment: #0 - Michael Ranweiler <[email protected]> - 2020-04-22
14:44:31 ==
+++ This bug was initially created as a clone of Bug #184073 +++
This bug is a follow on to LP 1866909 to address a missing piece - only
half the following patch was included in 5.4.0-24.28.
The upstream patch has an additional fix but it?s not critical for GA.
It can get included as part of bug fixes. It also affects only power.
The patch("powerpc/ima: fix secure boot rules in ima arch policy") is
posted to linux-integrity and linuxppc-dev mailing list
(https://lore.kernel.org/linux-integrity/1586549618-6106-1-git-send-
[email protected]/T/#u)
If there are any issues identified during further testing, they will get
opened as separate issue to be addressed later.
Thanks & Regards,
- Nayna
== Comment: #4 - Michael Ranweiler <[email protected]> - 2020-05-11
02:23:35 ==
Updated posting:
https://lore.kernel.org/linux-integrity/1588342612-14532-1-git-send-
[email protected]/T/#u
** Changed in: linux (Ubuntu)
Status: Incomplete => Triaged
** Changed in: ubuntu-power-systems
Status: Incomplete => Triaged
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https://bugs.launchpad.net/bugs/1877955
Title:
Fix for secure boot rules in IMA arch policy on powerpc
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