Hi Kees,
On 2020-07-24 11:39 a.m., Kees Cook wrote:
On Fri, Jul 24, 2020 at 11:23:37AM -0700, Kees Cook wrote:
On Thu, Jul 23, 2020 at 10:41:07PM -0700, Scott Branden wrote:
On 2020-07-23 12:15 p.m., Kees Cook wrote:
On Wed, Jul 22, 2020 at 03:29:26PM -0700, Scott Branden wrote:
These changes don't pass the kernel-selftest for partial reads I added
(which are at the end of this patch v2 series).
Oh, interesting. Is there any feedback in dmesg? I wonder if I have the
LSMs configured differently than you?
I have no LSMs configured that I know of.
Yes, there is failure in dmesg which is how I determined to add my
workaround.
Without workaround, dmesg log attached after booting and running
fw_run_tests.h
See change below added for temp workaround for issue.
[...]
+
+ whole_file = (offset == 0 && i_size <= buf_size);
A hack to get this passing I added which probably breaks some security?
if (whole_file) {
+ ret = security_kernel_read_file(file, id, whole_file);
+ if (ret)
+ goto out;
+
}
This would imply I did something wrong in the LSM hook refactoring (i.e.
some LSM is rejecting the !whole_file case, but if the entire call to
the hooks are skipped, it's okay).
What does this return on your test system:
echo $(cat /sys/kernel/security/lsm)
ima kernel configs are enabled but I don't enable security policies
on the kernel command line.
echo $(cat /sys/kernel/security/lsm)
cat: /sys/kernel/security/lsm: No such file or directory
Oh, er... CONFIG_SECURITYFS is missing?
Can you send me your .config?
Ah, nevermind, I found my config mistake. I thought I had the right
setting, but I'd missed CONFIG_IMA_APPRAISE=y. With that enabled, the
firmware tests _correctly_ fail, since IMA can't appraise partial reads.
So, this doesn't look like a bug to me.
Now I'm confused. The original patch series I made with IMA additions
under Mimi's direction
passed the kernel selftests with partial read. And
request_partial_firmware_into_buf therefore worked.
Your changes don't work with CONFIG_IMA_APPRAISE=y on? Is there a way
to make IMA ignore this file to make things work then?
Seems like another change is needed for IMA to ignore partial reads if
it can't appraise them?
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