linux-kernel - Re: TOMOYO in linux-next

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Message-Id: <200903270412.n2R4CG7o054009@www262.sakura.ne.jp>
Date:	Fri, 27 Mar 2009 13:12:16 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:	pavel@....cz, jmorris@...ei.org
Cc:	linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: TOMOYO in linux-next

Hello.

James Morris wrote:
> As for the rest of the feedback, please work with the developers to fix 
> any bugs or lack of documentation.
Thanks.

Pavel Machek wrote:
> Are those interfaces documented somewhere?
They are documented at http://tomoyo.sourceforge.jp/en/2.2.x/policy-reference.html .

> This is quite nasty. I don't think turning off enforcement in
> interrupt is good idea. ("fails open").
This is not "fails open". TOMOYO deals only operations which are allowed to
sleep (e.g. opening files, making directories). This in_interrupt() check is
for safety in case somebody who are not allowed to sleep called TOMOYO's
function by error.

> I'm not sure basing security on pids is good idea...
PID is used for reaching a domain which that PID is in, not for access control
decisions.

> Hmm, barrier is spelled otherwise, and I'm not sure I'd trust this:
> 
> +struct tomoyo_path_info_with_data {
> +       /* Keep "head" first, for this pointer is passed to tomoyo_free(). */
> +       struct tomoyo_path_info head;
> +       char bariier1[16]; /* Safeguard for overrun. */
> 
> I guess constants should be used here:
Oh, typo, thanks.
I think there is no need to use #define here, for nobody accesses
barrier1/barrier2.

> +#ifdef TOMOYO_DEBUG_DOMAIN_UNDELETE
> +                       if (domain2->is_deleted != 255)
> +                               printk(KERN_DEBUG
> +                                      "Marked %p as non undeletable\n",
> +                                      domain2);
> +#endif
> +                       domain2->is_deleted = 255;
> 
> (I don't know why we want undelete in tomoyo.)
This "undelete domain" feature was introduced to allow administrators switch
domain policy periodically.

> If it contains copyright, it should contain copyright. It probably
> should not contain version numbers.
TOMOYO's management tools want /sys/kernel/security/tomoyo/version .

> Can we get an interface that does not need as many strings/ as much
> string parsing?
A plain text interface splitted by ' ' and '\n' is cleaner than introducing
binary interface. (TOMOYO uses \040 for ' ' and \012 for '\n'. No worry for
' ' and '\n' in pathnames.)

> That's my main complaint: Documentation.*tomoyo nor
> Documentation.*TOMOYO does not exist, still this adds a *lot* of new
> user<->kernel interfaces.
> 
> New user<->kernel interaces should be documented and very carefuly
> reviewed; I don't think that happened here.
These user<->kernel interface are for TOMOYO's policy management tools,
not for general userland applications like /bin/bash /usr/sbin/sshd etc.

Regards.

----------------------------------------
TOMOYO: Fix a typo.

Signed-off-by: Kentaro Takeda <takedakn@...data.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Signed-off-by: Toshiharu Harada <haradats@...data.co.jp>
---
 security/tomoyo/common.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.29-git1.orig/security/tomoyo/common.h
+++ linux-2.6.29-git1/security/tomoyo/common.h
@@ -55,7 +55,7 @@ struct tomoyo_path_info {
 struct tomoyo_path_info_with_data {
 	/* Keep "head" first, for this pointer is passed to tomoyo_free(). */
 	struct tomoyo_path_info head;
-	char bariier1[16]; /* Safeguard for overrun. */
+	char barrier1[16]; /* Safeguard for overrun. */
 	char body[TOMOYO_MAX_PATHNAME_LEN];
 	char barrier2[16]; /* Safeguard for overrun. */
 };
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