Re: [PATCH v5 06/12] S.A.R.A.: WX protection

From: Randy Dunlap <rdunlap@infradead.org>
To: Salvatore Mesoraca <s.mesoraca16@gmail.com>,
	linux-kernel@vger.kernel.org
Cc: kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
	linux-security-module@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Brad Spengler <spender@grsecurity.net>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Christoph Hellwig <hch@infradead.org>,
	James Morris <james.l.morris@oracle.com>,
	Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
	PaX Team <pageexec@freemail.hu>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v5 06/12] S.A.R.A.: WX protection
Date: Sat, 6 Jul 2019 08:38:39 -0700	[thread overview]
Message-ID: <fcbf55e9-78dc-fb1a-e893-4fea8ebdc202@infradead.org> (raw)
In-Reply-To: <1562410493-8661-7-git-send-email-s.mesoraca16@gmail.com>

On 7/6/19 3:54 AM, Salvatore Mesoraca wrote:
> diff --git a/security/sara/Kconfig b/security/sara/Kconfig
> index b98cf27..54a96e0 100644
> --- a/security/sara/Kconfig
> +++ b/security/sara/Kconfig
> @@ -60,3 +60,77 @@ config SECURITY_SARA_NO_RUNTIME_ENABLE
>  
>  	  If unsure, answer Y.
>  
> +config SECURITY_SARA_WXPROT
> +	bool "WX Protection: W^X and W!->X protections"
> +	depends on SECURITY_SARA
> +	default y
> +	help
> +	  WX Protection aims to improve user-space programs security by applying:
> +	    - W^X memory restriction
> +	    - W!->X (once writable never executable) mprotect restriction
> +	    - Executable MMAP prevention
> +	  See Documentation/admin-guide/LSM/SARA.rst. for further information.

	                                        .rst for further information.

> +
> +	  If unsure, answer Y.
> +
> +choice
> +	prompt "Default action for W^X and W!->X protections"
> +	depends on SECURITY_SARA
> +	depends on SECURITY_SARA_WXPROT
> +	default SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_COMPLAIN_VERBOSE
> +
> +        help

Use tab instead of spaces for indentation above.

> +	  Choose the default behaviour of WX Protection when no config
> +	  rule matches or no rule is loaded.
> +	  For further information on available flags and their meaning
> +	  see Documentation/admin-guide/LSM/SARA.rst.
> +
> +	config SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_COMPLAIN_VERBOSE
> +		bool "Protections enabled but not enforced."
> +		help
> +		  All features enabled except "Executable MMAP prevention",
> +		  verbose reporting, but no actual enforce: it just complains.
> +		  Its numeric value is 0x3f, for more information see
> +		  Documentation/admin-guide/LSM/SARA.rst.
> +
> +        config SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_ENFORCE_VERBOSE
> +		bool "Full protection, verbose."
> +		help
> +		  All features enabled except "Executable MMAP prevention".
> +		  The enabled features will be enforced with verbose reporting.
> +		  Its numeric value is 0x2f, for more information see
> +		  Documentation/admin-guide/LSM/SARA.rst.
> +
> +        config SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_ENFORCE
> +		bool "Full protection, quiet."
> +		help
> +		  All features enabled except "Executable MMAP prevention".
> +		  The enabled features will be enforced quietly.
> +		  Its numeric value is 0xf, for more information see
> +		  Documentation/admin-guide/LSM/SARA.rst.
> +
> +	config SECURITY_SARA_WXPROT_DEFAULT_FLAGS_NONE
> +		bool "No protection at all."
> +		help
> +		  All features disabled.
> +		  Its numeric value is 0, for more information see
> +		  Documentation/admin-guide/LSM/SARA.rst.
> +endchoice
> +
> +config SECURITY_SARA_WXPROT_DISABLED
> +	bool "WX protection will be disabled at boot."
> +	depends on SECURITY_SARA_WXPROT
> +	default n

Omit "default n" please.

> +	help
> +	  If you say Y here WX protection won't be enabled at startup. You can
> +	  override this option via user-space utilities or at boot time via
> +	  "sara.wxprot_enabled=[0|1]" kernel parameter.
> +
> +	  If unsure, answer N.
> +
> +config SECURITY_SARA_WXPROT_DEFAULT_FLAGS
> +	hex
> +	default "0x3f" if SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_COMPLAIN_VERBOSE
> +	default "0x2f" if SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_ENFORCE_VERBOSE
> +	default "0xf" if SECURITY_SARA_WXPROT_DEFAULT_FLAGS_ALL_ENFORCE
> +	default "0" if SECURITY_SARA_WXPROT_DEFAULT_FLAGS_NONE

-- 
~Randy