linux-kernel - [PATCH] MODSIGN: only panic in fips mode if sig

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Date:	Tue, 22 Jan 2013 13:43:57 -0500
From:	Kyle McMartin <kyle@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	dhowells@...hat.com, rusty@...tcorp.com.au, jstancek@...hat.com
Subject: [PATCH] MODSIGN: only panic in fips mode if sig_enforce is set

Commit 1d0059f3a added a test to check if the system is booted in fips
mode, and if so, panic the system if an unsigned module is loaded.
However the wording of the changelog "in signature enforcing mode" leads
one to assume that sig_enforce should be set for the panic to occur and
that these two tests are transposed.

Move the test for -ENOKEY && !sig_enforce before the test of fips_mode,
so that err will be 0, and the panic will not trigger unless we've
explicitly disabled unsigned modules with sig_enforce set, so that
systemtap and 3rd party modules will work in fips mode. (This also
matches the behaviour by Red Hat Enterprise Linux 6.)

Things which need to deny module loading such as secure boot already set
sig_enforce, so there's no issue here.

Reported-by: Jan Stancek <jstancek@...hat.com>
Signed-off-by: Kyle McMartin <kyle@...hat.com>

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2460,11 +2460,11 @@ static int module_sig_check(struct load_info *info)
 	}

 	/* Not having a signature is only an error if we're strict. */
+	if (err == -ENOKEY && !sig_enforce)
+		err = 0;
 	if (err < 0 && fips_enabled)
 		panic("Module verification failed with error %d in FIPS mode\n",
 		      err);
-	if (err == -ENOKEY && !sig_enforce)
-		err = 0;

 	return err;
 }
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