Received-SPF: pass (google.com: domain of linux-kernel+bounces-145883-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Content-Type: text/plain;
	charset=us-ascii
Precedence: bulk
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.500.171.1.1\))
Subject: Re: [kpsingh:static_calls] [security] 9e15595ed0:
 Kernel_panic-not_syncing:lsm_static_call_init-Ran_out_of_static_slots
From: KP Singh <kpsingh@kernel.org>
In-Reply-To: <A9568514-FCB3-4715-9794-696383B2B7E8@kernel.org>
Date: Mon, 15 Apr 2024 22:42:20 +0200
Cc: Andrii Nakryiko <andrii@kernel.org>,
 Casey Schaufler <casey@schaufler-ca.com>,
 Kees Cook <keescook@chromium.org>,
 Song Liu <song@kernel.org>,
 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
 kernel test robot <oliver.sang@intel.com>,
 linux-kernel@vger.kernel.org,
 linux-security-module@vger.kernel.org,
 lkp@intel.com,
 oe-lkp@lists.linux.dev
Content-Transfer-Encoding: quoted-printable
Message-Id: <CD57788C-C9D6-4BA8-8352-90EBB6600D39@kernel.org>
References: <202404151225.ce542e38-lkp@intel.com>
 <757538DA-07A4-4332-BAFA-B864BFD06A76@kernel.org>
 <30876b80-c437-4916-b982-97c1a95c0747@I-love.SAKURA.ne.jp>
 <CAHC9VhS=hQuvv+Sw6cc2HwzcLApO7Rc3dAnqHytyzBpC1rokFA@mail.gmail.com>
 <CACYkzJ4G7hO0DNSBy4wpJG1PSgNkifuYcfOeTTpyVBtBtWvQSg@mail.gmail.com>
 <A9568514-FCB3-4715-9794-696383B2B7E8@kernel.org>
To: Paul Moore <paul@paul-moore.com>


> On 15 Apr 2024, at 17:47, KP Singh <kpsingh@kernel.org> wrote:
>=20
>=20

[...]

>> <penguin-kernel@i-love.sakura.ne.jp> wrote:
>>> On 2024/04/15 17:26, KP Singh wrote:
>>>> This seems like an odd config which does not enable STATIC_CALL, I =
am going to
>>>> make CONFIG_SECURITY depend on CONFIG_STATIC_CALL and make the =
dependency explicit.
>>>=20
>>> If CONFIG_SECURITY depends on CONFIG_STATIC_CALL, architectures =
which do not
>>> support CONFIG_STATIC_CALL can no longer use LSM ? That sounds a bad =
dependency.
>>=20
>> Agreed.  If the arch doesn't support static calls we need a fallback
>> solution for the LSM that is no worse than what we have now, and
>> preferably would still solve the issue of the BPF hooks active even
>> where this is no BPF program attached.
>=20
> Actually I take it back, when CONFIG_STATIC_CALL is not available, the =
implementation falls back to an indirect call. This crash is unrelated, =
I will debug further and post back.

 Apparently, when I smoke tested, I had CONFIG_IMA disabled so did not =
hit the bug. Well, now IMA is an LSM, so the following fixes it:

kpsingh@kpsingh:~/projects/linux$ git diff
diff --git a/include/linux/lsm_count.h b/include/linux/lsm_count.h
index dbb3c8573959..77803d117a30 100644
--- a/include/linux/lsm_count.h
+++ b/include/linux/lsm_count.h
@@ -78,6 +78,12 @@
 #define BPF_LSM_ENABLED
 #endif

+#if IS_ENABLED(CONFIG_IMA)
+#define IMA_ENABLED 1,
+#else
+#define IMA_ENABLED
+#endif
+
 #if IS_ENABLED(CONFIG_SECURITY_LANDLOCK)
 #define LANDLOCK_ENABLED 1,
 #else
@@ -103,6 +109,7 @@
                LOCKDOWN_ENABLED        \
                SAFESETID_ENABLED       \
                BPF_LSM_ENABLED         \
+               IMA_ENABLED             \
                LANDLOCK_ENABLED)


We don't need a CONFIG_STATIC_CALL dependency, th static_call code =
nicely falls back.

- KP

>=20
> - KP
>=20
>>=20
>> --=20
>> paul-moore.com
>=20