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From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: Matthew Garrett <mjg59@google.com>
Cc: linux-integrity <linux-integrity@vger.kernel.org>,
	Paul Moore <paul@paul-moore.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Eric Paris <eparis@parisplace.org>,
	selinux@tycho.nsa.gov, Casey Schaufler <casey@schaufler-ca.com>,
	LSM List <linux-security-module@vger.kernel.org>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Subject: Re: [PATCH V3 2/2] IMA: Support using new creds in appraisal policy
Date: Tue, 28 Nov 2017 17:33:10 -0500	[thread overview]
Message-ID: <1511908390.3473.30.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <CACdnJuvN6NxHLG=hS4iDRHBGWWdzFeUMfkF3ETRjXCbwiXpgnQ@mail.gmail.com>

On Tue, 2017-11-28 at 13:37 -0800, Matthew Garrett wrote:
> On Tue, Nov 28, 2017 at 1:35 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > On Tue, 2017-11-28 at 13:22 -0800, Matthew Garrett wrote:
> >> We need to check against the appropriate credentials structure, and
> >> since we're doing this before commit_creds() has been called we can't
> >> just do it against the one in the task structure.  For BPRM_CHECK
> >> that'll be current_cred(), which means there's no change in
> >> functionality, whereas for CREDS_CHECK it'll be the new credentials
> >> structure.
> >
> > The existing code calls security_task_getsecid() with "current" not
> > "current_cred".  Will replacing security_task_getsecid() with
> > security_cred_getsecid() return the same info for the original
> > BRPM_CHECK?
> 
> security_task_getsecid(current) will give the same results as
> security_cred_getsecid(current_creds())

Unwinding security_task_getsecid(current) looks like it is using
real_cred, while current_cred() is using cred.

selinux_task_getsecid() -> task_sid() -> cred_sid(__task_cred())

#define __task_cred(task)       \
        rcu_dereference((task)->real_cred)

selinux_task_getsecid() -> cred_sid()

#define current_cred() \
        rcu_dereference_protected(current->cred, 1)

Is the change intentional?

Mimi

WARNING: multiple messages have this Message-ID (diff)
From: zohar@linux.vnet.ibm.com (Mimi Zohar)
To: linux-security-module@vger.kernel.org
Subject: [PATCH V3 2/2] IMA: Support using new creds in appraisal policy
Date: Tue, 28 Nov 2017 17:33:10 -0500	[thread overview]
Message-ID: <1511908390.3473.30.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <CACdnJuvN6NxHLG=hS4iDRHBGWWdzFeUMfkF3ETRjXCbwiXpgnQ@mail.gmail.com>

On Tue, 2017-11-28 at 13:37 -0800, Matthew Garrett wrote:
> On Tue, Nov 28, 2017 at 1:35 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> > On Tue, 2017-11-28 at 13:22 -0800, Matthew Garrett wrote:
> >> We need to check against the appropriate credentials structure, and
> >> since we're doing this before commit_creds() has been called we can't
> >> just do it against the one in the task structure.  For BPRM_CHECK
> >> that'll be current_cred(), which means there's no change in
> >> functionality, whereas for CREDS_CHECK it'll be the new credentials
> >> structure.
> >
> > The existing code calls security_task_getsecid() with "current" not
> > "current_cred".  Will replacing security_task_getsecid() with
> > security_cred_getsecid() return the same info for the original
> > BRPM_CHECK?
> 
> security_task_getsecid(current) will give the same results as
> security_cred_getsecid(current_creds())

Unwinding security_task_getsecid(current) looks like it is using
real_cred, while current_cred() is using cred.

selinux_task_getsecid() -> task_sid() -> cred_sid(__task_cred())

#define __task_cred(task)       \
        rcu_dereference((task)->real_cred)

selinux_task_getsecid() -> cred_sid()

#define current_cred() \
        rcu_dereference_protected(current->cred, 1)

Is the change intentional?

Mimi

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  reply	other threads:[~2017-11-28 22:33 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-26  8:40 [PATCH V3 1/2] security: Add a cred_getsecid hook Matthew Garrett
2017-10-26  8:40 ` Matthew Garrett
2017-10-26  8:40 ` [PATCH V3 2/2] IMA: Support using new creds in appraisal policy Matthew Garrett
2017-10-26  8:40   ` Matthew Garrett
2017-10-26  9:11   ` James Morris
2017-10-26  9:11     ` James Morris
2017-11-28 20:48   ` Mimi Zohar
2017-11-28 20:48     ` Mimi Zohar
2017-11-28 20:48     ` Mimi Zohar
2017-11-28 21:22     ` Matthew Garrett
2017-11-28 21:22       ` Matthew Garrett
2017-11-28 21:35       ` Mimi Zohar
2017-11-28 21:35         ` Mimi Zohar
2017-11-28 21:35         ` Mimi Zohar
2017-11-28 21:37         ` Matthew Garrett
2017-11-28 21:37           ` Matthew Garrett
2017-11-28 22:33           ` Mimi Zohar [this message]
2017-11-28 22:33             ` Mimi Zohar
2017-12-15 22:24             ` Matthew Garrett
2017-12-15 22:24               ` Matthew Garrett
2017-12-15 22:35               ` Matthew Garrett
2017-12-15 22:35                 ` Matthew Garrett
2017-12-18 15:39                 ` Mimi Zohar
2017-12-18 15:39                   ` Mimi Zohar
2017-12-18 15:39                   ` Mimi Zohar
2017-10-26  9:04 ` [PATCH V3 1/2] security: Add a cred_getsecid hook James Morris
2017-10-26  9:04   ` James Morris
2017-10-26 13:21 ` Casey Schaufler
2017-10-26 13:21   ` Casey Schaufler
2017-10-30 10:54   ` Matthew Garrett
2017-10-30 10:54     ` Matthew Garrett
2017-10-26 14:20 ` Stephen Smalley
2017-10-26 14:20   ` Stephen Smalley
2017-10-26 14:20   ` Stephen Smalley
2017-10-30 10:57   ` Matthew Garrett
2017-10-30 10:57     ` Matthew Garrett
2017-10-30 17:03     ` Stephen Smalley
2017-10-30 17:03       ` Stephen Smalley
2017-10-30 17:03       ` Stephen Smalley
2017-11-14 19:42       ` Matthew Garrett
2017-11-14 19:42         ` Matthew Garrett

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