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From: "Jan Beulich" <JBeulich@suse.com>
To: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, xen-devel@lists.xen.org
Subject: Re: [PATCH 15/15] xsm: add a default policy to .init.data
Date: Fri, 10 Jun 2016 01:15:09 -0600	[thread overview]
Message-ID: <575A851D02000078000F3D8E@prv-mh.provo.novell.com> (raw)
In-Reply-To: <3adb76f3-ea0c-798f-6eb7-5f25976a0626@tycho.nsa.gov>

>>> On 09.06.16 at 18:58, <dgdegra@tycho.nsa.gov> wrote:
> On 06/09/2016 11:30 AM, Andrew Cooper wrote:
>> On 09/06/16 15:47, Daniel De Graaf wrote:
>>> diff --git a/xen/xsm/xsm_core.c b/xen/xsm/xsm_core.c
>>> index 4a264c2..6ffccb2 100644
>>> --- a/xen/xsm/xsm_core.c
>>> +++ b/xen/xsm/xsm_core.c
>>> @@ -36,6 +36,17 @@ static inline int verify(struct xsm_operations *ops)
>>>      return 0;
>>>  }
>>>
>>> +extern char __xsm_init_policy_start[], __xsm_init_policy_end[];
>>> +
>>> +static void __init xsm_policy_init(void)
>>> +{
>>> +    if ( policy_size == 0 && __xsm_init_policy_end != __xsm_init_policy_start )
>>> +    {
>>> +        policy_buffer = __xsm_init_policy_start;
>>
>> I think this might cause a problem for ARM.
>>
>> xsm_dt_init(void) does
>>
>> ret = xsm_core_init();
>> xfree(policy_buffer);
>>
>> which might now try freeing a piece of initdata.  Even going back to c/s
>> a8f2fb51c19 which introduced this code, I can't spot its justification.
> 
> The buffer is allocated and populated in xsm_dt_policy_init.

Only if there is an XSM module; I think Andrew refers to the
assignment to policy_buffer still visible above, which would
remain untouched by xsm_dt_policy_init() if bailing early.

>> It also looks like the entire policy buffer can be const, at which point
>> it can be linked slightly higher in .init.data with the other
>> logically-const data.
> 
> Sure, although this will require quite a bit of const propagation down into
> the FLASK security server (or casting it away).

No casting away of constness please, except in very special situations
(which this one pretty clearly isn't).

Jan


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  reply	other threads:[~2016-06-10  7:15 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-09 14:47 [PATCH 00/15] XSM/FLASK updates for 4.8 Daniel De Graaf
2016-06-09 14:47 ` [PATCH 01/15] flask/policy: split into modules Daniel De Graaf
2016-06-14 18:55   ` Konrad Rzeszutek Wilk
2016-06-20  5:15   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 02/15] flask/policy: split out rules for system_r Daniel De Graaf
2016-06-14 19:08   ` Konrad Rzeszutek Wilk
2016-06-20  5:21   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 03/15] flask/policy: move user definitions and constraints into modules Daniel De Graaf
2016-06-17 15:28   ` Konrad Rzeszutek Wilk
2016-06-17 16:49     ` Daniel De Graaf
2016-06-20  5:22   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 04/15] flask/policy: remove unused support for binary modules Daniel De Graaf
2016-06-20  5:22   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 05/15] flask/policy: xenstore stubdom policy Daniel De Graaf
2016-06-17 15:34   ` Konrad Rzeszutek Wilk
2016-06-20  5:22   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 06/15] flask/policy: remove unused example Daniel De Graaf
2016-06-17 15:34   ` Konrad Rzeszutek Wilk
2016-06-20  5:23   ` Doug Goldstein
2016-06-09 14:47 ` [PATCH 07/15] flask: unify {get, set}vcpucontext permissions Daniel De Graaf
2016-06-17 15:37   ` Konrad Rzeszutek Wilk
2016-06-09 14:47 ` [PATCH 08/15] flask: remove unused secondary context in ocontext Daniel De Graaf
2016-06-09 16:01   ` Jan Beulich
2016-06-09 16:38     ` Daniel De Graaf
2016-06-09 14:47 ` [PATCH 09/15] flask: remove unused AVC callback functions Daniel De Graaf
2016-06-09 14:47 ` [PATCH 10/15] flask: remove xen_flask_userlist operation Daniel De Graaf
2016-06-09 16:07   ` Jan Beulich
2016-06-09 16:43     ` Daniel De Graaf
2016-06-10  6:51       ` Jan Beulich
2016-06-10 13:08         ` Daniel De Graaf
2016-06-10 14:28           ` Jan Beulich
2016-06-09 14:47 ` [PATCH 11/15] flask: improve unknown permission handling Daniel De Graaf
2016-06-17 15:45   ` Konrad Rzeszutek Wilk
2016-06-17 17:02     ` Daniel De Graaf
2016-06-17 17:13       ` Konrad Rzeszutek Wilk
2016-06-17 17:20         ` Daniel De Graaf
2016-06-09 14:47 ` [PATCH 12/15] xen/xsm: remove .xsm_initcall.init section Daniel De Graaf
2016-06-09 15:14   ` Andrew Cooper
2016-06-09 16:11   ` Jan Beulich
2016-06-09 16:42     ` Daniel De Graaf
2016-06-17 15:50   ` Konrad Rzeszutek Wilk
2016-06-17 17:04     ` Daniel De Graaf
2016-06-17 17:14       ` Konrad Rzeszutek Wilk
2016-06-17 17:18         ` Daniel De Graaf
2016-06-17 17:21           ` Konrad Rzeszutek Wilk
2016-06-17 23:17             ` Daniel De Graaf
2016-06-09 14:47 ` [PATCH 13/15] xsm: annotate setup functions with __init Daniel De Graaf
2016-06-09 15:15   ` Andrew Cooper
2016-06-09 14:47 ` [PATCH 14/15] xsm: clean up unregistration Daniel De Graaf
2016-06-09 15:16   ` Andrew Cooper
2016-06-17 15:51   ` Konrad Rzeszutek Wilk
2016-06-09 14:47 ` [PATCH 15/15] xsm: add a default policy to .init.data Daniel De Graaf
2016-06-09 15:30   ` Andrew Cooper
2016-06-09 16:58     ` Daniel De Graaf
2016-06-10  7:15       ` Jan Beulich [this message]
2016-06-09 16:15   ` Jan Beulich
2016-06-09 16:53     ` Daniel De Graaf
2016-06-09 21:54       ` Doug Goldstein
2016-06-10 14:50         ` Daniel De Graaf
2016-06-10  6:53       ` Jan Beulich
2016-06-17 15:54   ` Konrad Rzeszutek Wilk
2016-06-17 16:00 ` [PATCH 00/15] XSM/FLASK updates for 4.8 Konrad Rzeszutek Wilk
2016-06-20  5:40 ` Doug Goldstein

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