linux-kernel - Re: [PATCH] Fix kexec forbidding kernels signed with custom platform keys to boot

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Message-ID: <654fbafb-69da-cd9a-b176-7b03401e71c5@sembritzki.me>
Date:   Wed, 15 Aug 2018 19:27:33 +0200
From:   Yannik Sembritzki <yannik@...britzki.me>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Peter Anvin <hpa@...or.com>,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Fix kexec forbidding kernels signed with custom platform
 keys to boot

Would this be okay?

diff --git a/arch/x86/kernel/kexec-bzimage64.c
b/arch/x86/kernel/kexec-bzimage64.c
index 7326078e..2ba47e24 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -41,6 +41,9 @@
 #define MIN_KERNEL_LOAD_ADDR   0x100000
 #define MIN_INITRD_LOAD_ADDR   0x1000000
 
+// Allow both builtin trusted keys and secondary trusted keys
+#define TRUST_FULL_KEYRING     (void *)1UL
+
 /*
  * This is a place holder for all boot loader specific data structure which
  * gets allocated in one call but gets freed much later during cleanup
@@ -532,7 +535,7 @@ static int bzImage64_cleanup(void *loader_data)
 static int bzImage64_verify_sig(const char *kernel, unsigned long
kernel_len)
 {
        return verify_pefile_signature(kernel, kernel_len,
-                                      NULL,
+                                      TRUST_FULL_KEYRING,
                                       VERIFYING_KEXEC_PE_SIGNATURE);
 }
 #endif
--

On 15.08.2018 18:54, Linus Torvalds wrote:
> This needs more people involved, and at least a sign-off.
>
> It looks ok, but I think we need a #define for the magical (void *)1UL
> thing. I see the use in verify_pkcs7_signature(), but still.
>
>               Linus
>
>
>
> On Wed, Aug 15, 2018 at 3:11 AM Yannik Sembritzki <yannik@...britzki.me> wrote:
>> ---
>>  arch/x86/kernel/kexec-bzimage64.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
>> index 7326078e..eaaa125d 100644
>> --- a/arch/x86/kernel/kexec-bzimage64.c
>> +++ b/arch/x86/kernel/kexec-bzimage64.c
>> @@ -532,7 +532,7 @@ static int bzImage64_cleanup(void *loader_data)
>>  static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
>>  {
>>         return verify_pefile_signature(kernel, kernel_len,
>> -                                      NULL,
>> +                                      (void *)1UL,
>>                                        VERIFYING_KEXEC_PE_SIGNATURE);
>>  }
>>  #endif
>> --
>> 2.17.1
>>
>> The exact scenario under which this issue occurs is described here:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1554113
>>