From: Takashi Iwai <tiwai@suse.de>
To: Roberto Sassu <roberto.sassu@huawei.com>
Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Oops at boot with linux-next kernel with IMA boot options
Date: Thu, 28 May 2020 18:37:12 +0200 [thread overview]
Message-ID: <s5hk10wm2x3.wl-tiwai@suse.de> (raw)
In-Reply-To: <s5htv00m5sb.wl-tiwai@suse.de>
On Thu, 28 May 2020 17:35:16 +0200,
Takashi Iwai wrote:
>
> Hi Roberto,
>
> it seems that the recent changes in IMA in linux-next caused a
> regression: namely it triggers an Oops when booting with the options
> ima_policy=tcb ima_template_fmt='d-ng|n-ng|d|ng'
And further experiment revealed that passing only ima_template_fmt=d
is enough for triggering the bug. Other formats don't matter.
(snip)
> It's a KVM instance without any TPM stuff, just passed the options
> above. I could trigger the same bug on a bare metal, too.
>
> Then I performed bisection and it spotted the commit:
> 6f1a1d103b48b1533a9c804e7a069e2c8e937ce7
> ima: Switch to ima_hash_algo for boot aggregate
>
> Actually reverting this commit fixed the Oops again.
So, looking at the fact above (triggered by "d") and this bisection
result, it seems that the issue is specific to ima_eventdigest_init().
The difference from others is that this has a check by
ima_template_hash_algo_allowed(), and currently the check allows only
SHA1 and MD5, while now SHA256 is assigned as default. So I tested
adding SHA256 there like below, and it seems working.
Hopefully I'm heading to a right direction...
thanks,
Takashi
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -13,7 +13,8 @@
static bool ima_template_hash_algo_allowed(u8 algo)
{
- if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
+ if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_SHA256 ||
+ algo == HASH_ALGO_MD5)
return true;
return false;
next prev parent reply other threads:[~2020-05-28 16:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 15:35 Oops at boot with linux-next kernel with IMA boot options Takashi Iwai
2020-05-28 16:37 ` Takashi Iwai [this message]
2020-05-28 17:36 ` Roberto Sassu
2020-05-28 18:02 ` Takashi Iwai
2020-05-29 7:33 ` Roberto Sassu
2020-05-29 7:45 ` Takashi Iwai
2020-05-31 18:50 ` Mimi Zohar
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