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Date: Thu, 08 Mar 2018 17:05:40 -0500
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Tycho Andersen <tycho@...ho.ws>
Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v2] ima: drop vla in ima_audit_measurement()
On Thu, 2018-03-08 at 14:45 -0700, Tycho Andersen wrote:
> Hi Mimi,
>
> On Thu, Mar 08, 2018 at 03:36:14PM -0500, Mimi Zohar wrote:
> > On Thu, 2018-03-08 at 13:23 -0700, Tycho Andersen wrote:
> >
> > > /*
> > > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> > > index 2cfb0c714967..356faae6f09c 100644
> > > --- a/security/integrity/ima/ima_main.c
> > > +++ b/security/integrity/ima/ima_main.c
> > > @@ -288,8 +288,11 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
> > > xattr_value, xattr_len, opened);
> > > inode_unlock(inode);
> > > }
> > > - if (action & IMA_AUDIT)
> > > - ima_audit_measurement(iint, pathname);
> > > + if (action & IMA_AUDIT) {
> > > + rc = ima_audit_measurement(iint, pathname);
> > > + if (rc < 0)
> > > + goto out_locked;
> > > + }
> > >
> > > if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
> > > rc = 0;
> >
> > Only when IMA-appraisal is enforcing file data integrity should
> > process_measurement() ever fail. Other errors can be logged/audited.
>
> Ok, so previously in ima_audit_measurement() when allocation failed,
> there was nothing logged. If we just keep this behavior like below,
> does that look good?
Before the IMA locking change that were just upstreamed, there were
problems with measuring/appraising files that were opened with the
O_DIRECT flag. Unless the IMA policy specified permit_directio, the
measurement/appraisal failed. With the new locking, opening files
with the O_DIRECTIO flag shouldn't be a problem. It just needs to be
fully tested before removing this code.
On failure, the code below tests the ima_audit_measurement() result
and skips the IMA_PERMIT_DIRECTIO test. Unless I'm missing something,
I don't see the point.
Mimi
> Thanks!
>
> Tycho
>
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 356faae6f09c..4e699bc7adc5 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -289,9 +289,13 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
> inode_unlock(inode);
> }
> if (action & IMA_AUDIT) {
> - rc = ima_audit_measurement(iint, pathname);
> - if (rc < 0)
> + int ret;
> +
> + ret = ima_audit_measurement(iint, pathname);
> + if (ret < 0 && ima_appraise & IMA_APPRAISE_ENFORCE) {
> + rc = ret;
> goto out_locked;
> + }
> }
>
> if ((file->f_flags & O_DIRECT) && (iint->flags & IMA_PERMIT_DIRECTIO))
>
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