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Date: Mon, 13 Aug 2012 10:46:20 -0700
From: Casey Schaufler <casey@...aufler-ca.com>
To: Jarkko Sakkinen <jarkko.sakkinen@...el.com>
CC: linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH] Smack: remove task_wait() hook.
On 8/13/2012 4:45 AM, Jarkko Sakkinen wrote:
> On Thu, Aug 09, 2012 at 05:46:38PM -0700, Casey Schaufler wrote:
>> On 12/20/2011 11:20 PM, Jarkko Sakkinen wrote:
>>> Allow SIGCHLD to be passed to child process without
>>> explicit policy. This will help to keep the access
>>> control policy simple and easily maintainable with
>>> complex applications that require use of multiple
>>> security contexts. It will also help to keep them
>>> as isolated as possible.
>>>
>>> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...el.com>
>> I have a slightly different version that applies to the
>> current smack-next tree.
>>
>> Allow SIGCHLD to be passed to child process without
>> explicit policy. This will help to keep the access
>> control policy simple and easily maintainable with
>> complex applications that require use of multiple
>> security contexts. It will also help to keep them
>> as isolated as possible.
>>
>> Signed-off-by: Casey Schaufler <casey@...aufler-ca.com>
> Acked-by: Jarkko Sakkinen <jarkko.sakkinen@...el.com>
Applied to git://git.gitorious.org/smack-next/kernel.git
>> security/smack/smack_lsm.c | 37 ++++++++-----------------------------
>> 1 files changed, 8 insertions(+), 29 deletions(-)
>>
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 8221514..ce9273a 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -1691,40 +1691,19 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
>> * smack_task_wait - Smack access check for waiting
>> * @p: task to wait for
>> *
>> - * Returns 0 if current can wait for p, error code otherwise
>> + * Returns 0
>> */
>> static int smack_task_wait(struct task_struct *p)
>> {
>> - struct smk_audit_info ad;
>> - char *sp = smk_of_current();
>> - char *tsp = smk_of_forked(task_security(p));
>> - int rc;
>> -
>> - /* we don't log here, we can be overriden */
>> - rc = smk_access(tsp, sp, MAY_WRITE, NULL);
>> - if (rc == 0)
>> - goto out_log;
>> -
>> /*
>> - * Allow the operation to succeed if either task
>> - * has privilege to perform operations that might
>> - * account for the smack labels having gotten to
>> - * be different in the first place.
>> - *
>> - * This breaks the strict subject/object access
>> - * control ideal, taking the object's privilege
>> - * state into account in the decision as well as
>> - * the smack value.
>> + * Allow the operation to succeed.
>> + * Zombies are bad.
>> + * In userless environments (e.g. phones) programs
>> + * get marked with SMACK64EXEC and even if the parent
>> + * and child shouldn't be talking the parent still
>> + * may expect to know when the child exits.
>> */
>> - if (smack_privileged(CAP_MAC_OVERRIDE) ||
>> - has_capability(p, CAP_MAC_OVERRIDE))
>> - rc = 0;
>> - /* we log only if we didn't get overriden */
>> - out_log:
>> - smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
>> - smk_ad_setfield_u_tsk(&ad, p);
>> - smack_log(tsp, sp, MAY_WRITE, rc, &ad);
>> - return rc;
>> + return 0;
>> }
>>
>> /**
>>
>>> ---
>>> security/smack/smack_lsm.c | 40 ----------------------------------------
>>> 1 files changed, 0 insertions(+), 40 deletions(-)
>>>
>>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>>> index 7db62b4..cc788f5 100644
>>> --- a/security/smack/smack_lsm.c
>>> +++ b/security/smack/smack_lsm.c
>>> @@ -1685,45 +1685,6 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
>>> }
>>>
>>> /**
>>> - * smack_task_wait - Smack access check for waiting
>>> - * @p: task to wait for
>>> - *
>>> - * Returns 0 if current can wait for p, error code otherwise
>>> - */
>>> -static int smack_task_wait(struct task_struct *p)
>>> -{
>>> - struct smk_audit_info ad;
>>> - char *sp = smk_of_current();
>>> - char *tsp = smk_of_forked(task_security(p));
>>> - int rc;
>>> -
>>> - /* we don't log here, we can be overriden */
>>> - rc = smk_access(tsp, sp, MAY_WRITE, NULL);
>>> - if (rc == 0)
>>> - goto out_log;
>>> -
>>> - /*
>>> - * Allow the operation to succeed if either task
>>> - * has privilege to perform operations that might
>>> - * account for the smack labels having gotten to
>>> - * be different in the first place.
>>> - *
>>> - * This breaks the strict subject/object access
>>> - * control ideal, taking the object's privilege
>>> - * state into account in the decision as well as
>>> - * the smack value.
>>> - */
>>> - if (capable(CAP_MAC_OVERRIDE) || has_capability(p, CAP_MAC_OVERRIDE))
>>> - rc = 0;
>>> - /* we log only if we didn't get overriden */
>>> - out_log:
>>> - smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
>>> - smk_ad_setfield_u_tsk(&ad, p);
>>> - smack_log(tsp, sp, MAY_WRITE, rc, &ad);
>>> - return rc;
>>> -}
>>> -
>>> -/**
>>> * smack_task_to_inode - copy task smack into the inode blob
>>> * @p: task to copy from
>>> * @inode: inode to copy to
>>> @@ -3549,7 +3510,6 @@ struct security_operations smack_ops = {
>>> .task_getscheduler = smack_task_getscheduler,
>>> .task_movememory = smack_task_movememory,
>>> .task_kill = smack_task_kill,
>>> - .task_wait = smack_task_wait,
>>> .task_to_inode = smack_task_to_inode,
>>>
>>> .ipc_permission = smack_ipc_permission,
> /Jarkko
>
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