Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Tetsuo Handa]

Casey Schaufler wrote:
> On 2/6/2019 2:23 AM, Tetsuo Handa wrote:
> > But as I update the documentation ( https://tomoyo.osdn.jp/2.6/chapter-3.html.en#3.6 ),
> > I came to think that we should ignore security= parameter when lsm= parameter is specified.
> >
> > Currently, it is possible to enable TOMOYO and only one of SELinux/Smack/AppArmor. Therefore,
> > it is possible to disable only TOMOYO by specifying security=selinux when we want to enable
> > only SELinux, by specifying security=smack when we want to enable only Smack, by specifying
> > security=apparmor when we want to enable only AppArmor. That is, we can use security= parameter
> > in order to specify the other LSM module which should not be disabled.
> >
> > But when it becomes possible to enable TOMOYO and more than one of SELinux/Smack/AppArmor,
> > we will no longer be able to selectively disable one LSM module using security= parameter, for
> > security= parameter is intended for specifying only one LSM module which should be enabled.
> > That is, we will need to use lsm= parameter in order to selectively disable LSM modules.
> 
> Yes. That is correct. The existing behavior of security= is maintained.

But the existing behavior of CONFIG_DEFAULT_SECURITY is not maintained.
This might cause a problem like

  commit e5a3b95f581da62e2054ef79d3be2d383e9ed664
  Author: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
  Date:   Sat Feb 14 11:46:56 2009 +0900

      TOMOYO: Don't create securityfs entries unless registered.

      TOMOYO should not create /sys/kernel/security/tomoyo/ interface unless
      TOMOYO is registered.

for Ubuntu users because Ubuntu kernels are built with

  CONFIG_SECURITY_SELINUX=y
  CONFIG_SECURITY_SMACK=y
  CONFIG_SECURITY_TOMOYO=y
  CONFIG_SECURITY_APPARMOR=y
  CONFIG_SECURITY_YAMA=y
  CONFIG_DEFAULT_SECURITY="apparmor"

. Due to CONFIG_DEFAULT_SECURITY="apparmor", majority of Ubuntu users are enabling
only AppArmor without explicitly specifying "security=apparmor".

Currently default CONFIG_LSM setting is

  "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"

but Ubuntu kernels would have to be built with non-default CONFIG_LSM setting like

  "yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo"

in order to make sure that AppArmor is by default chosen for the LSM_FLAG_EXCLUSIVE module.

Now that TOMOYO becomes a !LSM_FLAG_EXCLUSIVE module, not specifying "security=apparmor" will
automatically enable TOMOYO. And majority of Ubuntu users will unexpectedly encounter TOMOYO
messages. But removing "tomoyo" from CONFIG_LSM setting in order to save majority of Ubuntu
users from unexpectedly encountering TOMOYO messages also has a problem; Ubuntu users who want
to enable only TOMOYO from LSM_FLAG_LEGACY_MAJOR modules can specify "security=tomoyo", but
Ubuntu users who want to enable TOMOYO and one of SELinux,Smack,AppArmor (including syzbot)
will have to explicitly specify "lsm=" because "security=" can't allow enabling multiple
LSM_FLAG_LEGACY_MAJOR modules.

> The new behavior of lsm= is provided to allow general handling of a list
> of security modules. It uses the same form of data as CONFIG_LSM.
> 
> > Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
> > when lsm= parameter is specified.
> 
> That reduces flexibility somewhat. If I am debugging security modules
> I may want to use lsm= to specify the order while using security= to
> identify a specific exclusive module. I could do that using lsm= by
> itself, but habits die hard.

"lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).

Since "security=" can't be used for selectively enable/disable more than one of
SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Casey Schaufler]

On 2/6/2019 6:30 PM, Tetsuo Handa wrote:
> Casey Schaufler wrote:
>> On 2/6/2019 2:23 AM, Tetsuo Handa wrote:
>>> But as I update the documentation ( https://tomoyo.osdn.jp/2.6/chapter-3.html.en#3.6 ),
>>> I came to think that we should ignore security= parameter when lsm= parameter is specified.
>>>
>>> Currently, it is possible to enable TOMOYO and only one of SELinux/Smack/AppArmor. Therefore,
>>> it is possible to disable only TOMOYO by specifying security=selinux when we want to enable
>>> only SELinux, by specifying security=smack when we want to enable only Smack, by specifying
>>> security=apparmor when we want to enable only AppArmor. That is, we can use security= parameter
>>> in order to specify the other LSM module which should not be disabled.
>>>
>>> But when it becomes possible to enable TOMOYO and more than one of SELinux/Smack/AppArmor,
>>> we will no longer be able to selectively disable one LSM module using security= parameter, for
>>> security= parameter is intended for specifying only one LSM module which should be enabled.
>>> That is, we will need to use lsm= parameter in order to selectively disable LSM modules.
>> Yes. That is correct. The existing behavior of security= is maintained.
> But the existing behavior of CONFIG_DEFAULT_SECURITY is not maintained.

That's a developer interface, not a user interface. I realize
that may be splitting hairs, but it had to change.

> This might cause a problem like
>
>   commit e5a3b95f581da62e2054ef79d3be2d383e9ed664
>   Author: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>   Date:   Sat Feb 14 11:46:56 2009 +0900
>
>       TOMOYO: Don't create securityfs entries unless registered.
>
>       TOMOYO should not create /sys/kernel/security/tomoyo/ interface unless
>       TOMOYO is registered.
>
> for Ubuntu users because Ubuntu kernels are built with
>
>   CONFIG_SECURITY_SELINUX=y
>   CONFIG_SECURITY_SMACK=y
>   CONFIG_SECURITY_TOMOYO=y
>   CONFIG_SECURITY_APPARMOR=y
>   CONFIG_SECURITY_YAMA=y
>   CONFIG_DEFAULT_SECURITY="apparmor"
>
> . Due to CONFIG_DEFAULT_SECURITY="apparmor", majority of Ubuntu users are enabling
> only AppArmor without explicitly specifying "security=apparmor".
>
> Currently default CONFIG_LSM setting is
>
>   "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
>
> but Ubuntu kernels would have to be built with non-default CONFIG_LSM setting like
>
>   "yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo"
>
> in order to make sure that AppArmor is by default chosen for the LSM_FLAG_EXCLUSIVE module.

Yes, and Yocto Project is likely to want Smack specified first.

> Now that TOMOYO becomes a !LSM_FLAG_EXCLUSIVE module, not specifying "security=apparmor" will
> automatically enable TOMOYO. And majority of Ubuntu users will unexpectedly encounter TOMOYO
> messages. But removing "tomoyo" from CONFIG_LSM setting in order to save majority of Ubuntu
> users from unexpectedly encountering TOMOYO messages also has a problem; Ubuntu users who want
> to enable only TOMOYO from LSM_FLAG_LEGACY_MAJOR modules can specify "security=tomoyo", but
> Ubuntu users who want to enable TOMOYO and one of SELinux,Smack,AppArmor (including syzbot)
> will have to explicitly specify "lsm=" because "security=" can't allow enabling multiple
> LSM_FLAG_LEGACY_MAJOR modules.

I believe we got general buy in from Ubuntu, and I understand
that the LSM list is awkward, but I don't see a rational alternate.
I know that I played with a half dozen, and nothing was closer to
maintaining the status quo.

>> The new behavior of lsm= is provided to allow general handling of a list
>> of security modules. It uses the same form of data as CONFIG_LSM.
>>
>>> Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
>>> when lsm= parameter is specified.
>> That reduces flexibility somewhat. If I am debugging security modules
>> I may want to use lsm= to specify the order while using security= to
>> identify a specific exclusive module. I could do that using lsm= by
>> itself, but habits die hard.
> "lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
> have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
> to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).
>
> Since "security=" can't be used for selectively enable/disable more than one of
> SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
> better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.

I added Kees to the CC list. Kees, what to you think about
ignoring security= if lsm= is specified? I'm ambivalent.

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Tetsuo Handa]

On 2019/02/08 1:24, Casey Schaufler wrote:
>>>> Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
>>>> when lsm= parameter is specified.
>>> That reduces flexibility somewhat. If I am debugging security modules
>>> I may want to use lsm= to specify the order while using security= to
>>> identify a specific exclusive module. I could do that using lsm= by
>>> itself, but habits die hard.
>> "lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
>> have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
>> to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).
>>
>> Since "security=" can't be used for selectively enable/disable more than one of
>> SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
>> better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.
> 
> I added Kees to the CC list. Kees, what to you think about
> ignoring security= if lsm= is specified? I'm ambivalent.
> 
> 

To help administrators easily understand what LSM modules are possibly enabled by default (which
have to be fetched from e.g. /boot/config-`uname -r`) and specify lsm= parameter when they need,
I propose changes shown below.

diff --git a/security/security.c b/security/security.c
index 3147785e..051d708 100644
--- a/security/security.c
+++ b/security/security.c
@@ -51,8 +51,6 @@
 static __initdata const char *chosen_lsm_order;
 static __initdata const char *chosen_major_lsm;
 
-static __initconst const char * const builtin_lsm_order = CONFIG_LSM;
-
 /* Ordered list of LSMs to initialize. */
 static __initdata struct lsm_info **ordered_lsms;
 static __initdata struct lsm_info *exclusive;
@@ -284,14 +282,22 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 static void __init ordered_lsm_init(void)
 {
 	struct lsm_info **lsm;
+	const char *order = CONFIG_LSM;
+	const char *origin = "builtin";
 
 	ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
 				GFP_KERNEL);
 
-	if (chosen_lsm_order)
-		ordered_lsm_parse(chosen_lsm_order, "cmdline");
-	else
-		ordered_lsm_parse(builtin_lsm_order, "builtin");
+	if (chosen_lsm_order) {
+		if (chosen_major_lsm) {
+			pr_info("security= is ignored because of lsm=\n");
+			chosen_major_lsm = NULL;
+		}
+		order = chosen_lsm_order;
+		origin = "cmdline";
+	}
+	pr_info("Security Framework initializing: %s\n", order);
+	ordered_lsm_parse(order, origin);
 
 	for (lsm = ordered_lsms; *lsm; lsm++)
 		prepare_lsm(*lsm);
@@ -333,8 +339,6 @@ int __init security_init(void)
 	int i;
 	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
 
-	pr_info("Security Framework initializing\n");
-
 	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
 	     i++)
 		INIT_HLIST_HEAD(&list[i]);

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Casey Schaufler]

On 2/8/2019 2:52 AM, Tetsuo Handa wrote:
> On 2019/02/08 1:24, Casey Schaufler wrote:
>>>>> Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
>>>>> when lsm= parameter is specified.
>>>> That reduces flexibility somewhat. If I am debugging security modules
>>>> I may want to use lsm= to specify the order while using security= to
>>>> identify a specific exclusive module. I could do that using lsm= by
>>>> itself, but habits die hard.
>>> "lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
>>> have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
>>> to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).
>>>
>>> Since "security=" can't be used for selectively enable/disable more than one of
>>> SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
>>> better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.
>> I added Kees to the CC list. Kees, what to you think about
>> ignoring security= if lsm= is specified? I'm ambivalent.
>>
>>
> To help administrators easily understand what LSM modules are possibly enabled by default (which
> have to be fetched from e.g. /boot/config-`uname -r`)

$ cat /sys/kernel/security/lsm

>  and specify lsm= parameter when they need,
> I propose changes shown below.
>
> diff --git a/security/security.c b/security/security.c
> index 3147785e..051d708 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -51,8 +51,6 @@
>  static __initdata const char *chosen_lsm_order;
>  static __initdata const char *chosen_major_lsm;
>  
> -static __initconst const char * const builtin_lsm_order = CONFIG_LSM;
> -
>  /* Ordered list of LSMs to initialize. */
>  static __initdata struct lsm_info **ordered_lsms;
>  static __initdata struct lsm_info *exclusive;
> @@ -284,14 +282,22 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  static void __init ordered_lsm_init(void)
>  {
>  	struct lsm_info **lsm;
> +	const char *order = CONFIG_LSM;
> +	const char *origin = "builtin";
>  
>  	ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
>  				GFP_KERNEL);
>  
> -	if (chosen_lsm_order)
> -		ordered_lsm_parse(chosen_lsm_order, "cmdline");
> -	else
> -		ordered_lsm_parse(builtin_lsm_order, "builtin");
> +	if (chosen_lsm_order) {
> +		if (chosen_major_lsm) {
> +			pr_info("security= is ignored because of lsm=\n");
> +			chosen_major_lsm = NULL;
> +		}
> +		order = chosen_lsm_order;
> +		origin = "cmdline";
> +	}
> +	pr_info("Security Framework initializing: %s\n", order);
> +	ordered_lsm_parse(order, origin);
>  
>  	for (lsm = ordered_lsms; *lsm; lsm++)
>  		prepare_lsm(*lsm);
> @@ -333,8 +339,6 @@ int __init security_init(void)
>  	int i;
>  	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
>  
> -	pr_info("Security Framework initializing\n");
> -
>  	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
>  	     i++)
>  		INIT_HLIST_HEAD(&list[i]);

I'm not going to object to this, but I don't see it as important.

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Tetsuo Handa]

On 2019/02/09 1:23, Casey Schaufler wrote:
> On 2/8/2019 2:52 AM, Tetsuo Handa wrote:
>> To help administrators easily understand what LSM modules are possibly enabled by default (which
>> have to be fetched from e.g. /boot/config-`uname -r`)
> 
> $ cat /sys/kernel/security/lsm
> 

/sys/kernel/security/lsm is list of "actually" enabled modules, isn't it?
What I want is "possibly" enabled modules. Ubuntu would chose from either

  (a) explicitly add security=apparmor to kernel command line

or

  (b) explicitly remove tomoyo from CONFIG_LSM at kernel config

in order not to enable TOMOYO for those who want to enable only one of 
SELinux/Smack/AppArmor. And for those who want to enable TOMOYO, I think
that (b) (in other words, add

  lsm="modules listed in CONFIG_LSM" + ",tomoyo"

) will retain compatibility when it becomes possible to enable more than
one of SELinux/Smack/AppArmor at the same time.

If we can know "possibly" enabled modules from dmesg, users don't need to
look at e.g. /boot/config-`uname -r`. It is not essential, but it's handy.

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Tetsuo Handa]

On 2019/02/09 9:28, Tetsuo Handa wrote:
> On 2019/02/09 1:23, Casey Schaufler wrote:
>> On 2/8/2019 2:52 AM, Tetsuo Handa wrote:
>>> To help administrators easily understand what LSM modules are possibly enabled by default (which
>>> have to be fetched from e.g. /boot/config-`uname -r`)
>>
>> $ cat /sys/kernel/security/lsm
>>
> 
> /sys/kernel/security/lsm is list of "actually" enabled modules, isn't it?
> What I want is "possibly" enabled modules. Ubuntu would chose from either
> 
>   (a) explicitly add security=apparmor to kernel command line
> 
> or
> 
>   (b) explicitly remove tomoyo from CONFIG_LSM at kernel config
> 
> in order not to enable TOMOYO for those who want to enable only one of 
> SELinux/Smack/AppArmor. And for those who want to enable TOMOYO, I think
> that (b) (in other words, add
> 
>   lsm="modules listed in CONFIG_LSM" + ",tomoyo"
> 
> ) will retain compatibility when it becomes possible to enable more than
> one of SELinux/Smack/AppArmor at the same time.
> 
> If we can know "possibly" enabled modules from dmesg, users don't need to
> look at e.g. /boot/config-`uname -r`. It is not essential, but it's handy.
> 

Well, thinking again, specifying

lsm="modules listed in /sys/kernel/security/lsm" + ",tomoyo"

makes sense, for there is no need to care about disabled modules when
enabling TOMOYO. Therefore,

+	pr_info("Security Framework initializing: %s\n", order);
-	pr_info("Security Framework initializing\n");

won't be needed.

On 2019/02/09 6:33, Kees Cook wrote:
> On Thu, Feb 7, 2019 at 8:24 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
>> I added Kees to the CC list. Kees, what to you think about
>> ignoring security= if lsm= is specified? I'm ambivalent.
> 
> This was one of many earlier suggestions, and the consensus seemed to
> be "don't mix security= and lsm=". Why would anyone use both?
> 

Then, can we add this change?

+	if (chosen_lsm_order) {
+		if (chosen_major_lsm) {
+			pr_info("security= is ignored because of lsm=\n");
+			chosen_major_lsm = NULL;
+		}
+	}

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Kees Cook]

On Fri, Feb 8, 2019 at 2:52 AM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> On 2019/02/08 1:24, Casey Schaufler wrote:
> >>>> Then, I think that it is straightforward (and easier to manage) to ignore security= parameter
> >>>> when lsm= parameter is specified.
> >>> That reduces flexibility somewhat. If I am debugging security modules
> >>> I may want to use lsm= to specify the order while using security= to
> >>> identify a specific exclusive module. I could do that using lsm= by
> >>> itself, but habits die hard.
> >> "lsm=" can be used for identifying a specific exclusive module, and Ubuntu kernels would
> >> have to use CONFIG_LSM (or "lsm=") for identifying the default exclusive module (in order
> >> to allow enabling both TOMOYO and one of SELinux,Smack,AppArmor at the same time).
> >>
> >> Since "security=" can't be used for selectively enable/disable more than one of
> >> SELinux,Smack,TOMOYO,AppArmor, I think that recommending users to migrate to "lsm=" is the
> >> better direction. And ignoring "security=" when "lsm=" is specified is easier to understand.
> >
> > I added Kees to the CC list. Kees, what to you think about
> > ignoring security= if lsm= is specified? I'm ambivalent.
> >
> >
>
> To help administrators easily understand what LSM modules are possibly enabled by default (which
> have to be fetched from e.g. /boot/config-`uname -r`) and specify lsm= parameter when they need,
> I propose changes shown below.
>
> diff --git a/security/security.c b/security/security.c
> index 3147785e..051d708 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -51,8 +51,6 @@
>  static __initdata const char *chosen_lsm_order;
>  static __initdata const char *chosen_major_lsm;
>
> -static __initconst const char * const builtin_lsm_order = CONFIG_LSM;
> -
>  /* Ordered list of LSMs to initialize. */
>  static __initdata struct lsm_info **ordered_lsms;
>  static __initdata struct lsm_info *exclusive;
> @@ -284,14 +282,22 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
>  static void __init ordered_lsm_init(void)
>  {
>         struct lsm_info **lsm;
> +       const char *order = CONFIG_LSM;
> +       const char *origin = "builtin";
>
>         ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
>                                 GFP_KERNEL);
>
> -       if (chosen_lsm_order)
> -               ordered_lsm_parse(chosen_lsm_order, "cmdline");
> -       else
> -               ordered_lsm_parse(builtin_lsm_order, "builtin");
> +       if (chosen_lsm_order) {
> +               if (chosen_major_lsm) {
> +                       pr_info("security= is ignored because of lsm=\n");

This is intended to be the new default way to change the LSM
("lsm=..."), so I'd rather not have this appear every time. Also, it
must continue to interact with the builtin ordering, so if you wanted
this, I think better would be to do:

diff --git a/security/security.c b/security/security.c
index 3147785e20d7..e6153ed54361 100644
--- a/security/security.c
+++ b/security/security.c
@@ -288,9 +288,13 @@ static void __init ordered_lsm_init(void)
        ordered_lsms = kcalloc(LSM_COUNT + 1, sizeof(*ordered_lsms),
                                GFP_KERNEL);

-       if (chosen_lsm_order)
+       if (chosen_lsm_order) {
+               if (chosen_major_lsm) {
+                       pr_info("security= is ignored because of lsm=\n");
+                       chosen_major_lsm = NULL;
+               }
                ordered_lsm_parse(chosen_lsm_order, "cmdline");
-       else
+       } else
                ordered_lsm_parse(builtin_lsm_order, "builtin");

        for (lsm = ordered_lsms; *lsm; lsm++)

> +       pr_info("Security Framework initializing: %s\n", order);
> +       ordered_lsm_parse(order, origin);
>
>         for (lsm = ordered_lsms; *lsm; lsm++)
>                 prepare_lsm(*lsm);
> @@ -333,8 +339,6 @@ int __init security_init(void)
>         int i;
>         struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
>
> -       pr_info("Security Framework initializing\n");
> -
>         for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
>              i++)
>                 INIT_HLIST_HEAD(&list[i]);



-- 
Kees Cook

Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

[Kees Cook]

On Thu, Feb 7, 2019 at 8:24 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
> I added Kees to the CC list. Kees, what to you think about
> ignoring security= if lsm= is specified? I'm ambivalent.

This was one of many earlier suggestions, and the consensus seemed to
be "don't mix security= and lsm=". Why would anyone use both?

-- 
Kees Cook