Re: [PATCH 23/28] security: Introduce LSM_ORDER_LAST

From: Mimi Zohar <zohar@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>,
	viro@zeniv.linux.org.uk, chuck.lever@oracle.com,
	jlayton@kernel.org, dmitry.kasatkin@gmail.com,
	paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com,
	dhowells@redhat.com, jarkko@kernel.org,
	stephen.smalley.work@gmail.com, eparis@parisplace.org,
	casey@schaufler-ca.com, brauner@kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
	selinux@vger.kernel.org, linux-kernel@vger.kernel.org,
	stefanb@linux.ibm.com, Roberto Sassu <roberto.sassu@huawei.com>
Subject: Re: [PATCH 23/28] security: Introduce LSM_ORDER_LAST
Date: Wed, 08 Mar 2023 08:13:27 -0500	[thread overview]
Message-ID: <a0320926ebfe732dabc4e53c3a35ede450c75474.camel@linux.ibm.com> (raw)
In-Reply-To: <20230303182602.1088032-1-roberto.sassu@huaweicloud.com>

Hi Roberto,

On Fri, 2023-03-03 at 19:25 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> 
> Introduce LSM_ORDER_LAST, to satisfy the requirement of LSMs willing to be
> the last, e.g. the 'integrity' LSM, without changing the kernel command
> line or configuration.

Please reframe this as a bug fix for 79f7865d844c ("LSM: Introduce
"lsm=" for boottime LSM selection") and upstream it first, with
'integrity' as the last LSM.   The original bug fix commit 92063f3ca73a
("integrity: double check iint_cache was initialized") could then be
removed.

> 
> As for LSM_ORDER_FIRST, LSMs with LSM_ORDER_LAST are always enabled and put
> at the end of the LSM list in no particular order.

^Similar to LSM_ORDER_FIRST ...

And remove "in no particular order".

> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>  include/linux/lsm_hooks.h |  1 +
>  security/security.c       | 12 +++++++++---
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 21a8ce23108..05c4b831d99 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -93,6 +93,7 @@ extern void security_add_hooks(struct security_hook_list *hooks, int count,
>  enum lsm_order {
>  	LSM_ORDER_FIRST = -1,	/* This is only for capabilities. */
>  	LSM_ORDER_MUTABLE = 0,
> +	LSM_ORDER_LAST = 1,
>  };
>  
>  struct lsm_info {
> diff --git a/security/security.c b/security/security.c
> index 322090a50cd..24f52ba3218 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -284,9 +284,9 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  		bool found = false;
>  
>  		for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
> -			if (lsm->order == LSM_ORDER_MUTABLE &&
> -			    strcmp(lsm->name, name) == 0) {
> -				append_ordered_lsm(lsm, origin);
> +			if (strcmp(lsm->name, name) == 0) {
> +				if (lsm->order == LSM_ORDER_MUTABLE)
> +					append_ordered_lsm(lsm, origin);
>  				found = true;
>  			}
>  		}
> @@ -306,6 +306,12 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  		}
>  	}
>  
> +	/* LSM_ORDER_LAST is always last. */
> +	for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
> +		if (lsm->order == LSM_ORDER_LAST)
> +			append_ordered_lsm(lsm, "   last");
> +	}
> +
>  	/* Disable all LSMs not in the ordered list. */
>  	for (lsm = __start_lsm_info; lsm < __end_lsm_info; lsm++) {
>  		if (exists_ordered_lsm(lsm))

-- 
thanks,

Mimi