linux-kernel - Re: [PATCH V34 29/29] lockdown: Print current->comm in restriction messages

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Message-ID: <201906221724.EF1BA1D@keescook>
Date:   Sat, 22 Jun 2019 17:25:28 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Matthew Garrett <matthewgarrett@...gle.com>
Cc:     jmorris@...ei.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        David Howells <dhowells@...hat.com>,
        Matthew Garrett <mjg59@...gle.com>
Subject: Re: [PATCH V34 29/29] lockdown: Print current->comm in restriction
 messages

On Fri, Jun 21, 2019 at 05:03:58PM -0700, Matthew Garrett wrote:
> Print the content of current->comm in messages generated by lockdown to
> indicate a restriction that was hit.  This makes it a bit easier to find
> out what caused the message.
> 
> The message now patterned something like:
> 
>         Lockdown: <comm>: <what> is restricted; see man kernel_lockdown.7
> 
> Signed-off-by: David Howells <dhowells@...hat.com>
> Signed-off-by: Matthew Garrett <mjg59@...gle.com>
> ---
>  security/lockdown/lockdown.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index 98f9ee0026d5..9ca6f442fbc7 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -83,8 +83,8 @@ static int lockdown_is_locked_down(enum lockdown_reason what)
>  {	
>  	if ((kernel_locked_down >= what)) {

To satisfy my paranoia, can you just add here:

		if (WARN(what > LOCKDOWN_..._MAX))
			return -EPERM;

With that:

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

>  		if (lockdown_reasons[what])
> -			pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n",
> -				  lockdown_reasons[what]);
> +			pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
> +				  current->comm, lockdown_reasons[what]);
>  		return -EPERM;
>  	}
>  
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
> 

-- 
Kees Cook