linux-kernel - Re: [PATCH] KEYS: encrypted: Add check for strsep

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Date: Mon, 12 Feb 2024 05:11:57 +0000
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Mimi Zohar" <zohar@...ux.ibm.com>, "Dan Williams"
 <dan.j.williams@...el.com>, "Verma, Vishal L" <vishal.l.verma@...el.com>,
 "paul@...l-moore.com" <paul@...l-moore.com>, "dhowells@...hat.com"
 <dhowells@...hat.com>, "yaelt@...gle.com" <yaelt@...gle.com>,
 "serge@...lyn.com" <serge@...lyn.com>, "nichen@...as.ac.cn"
 <nichen@...as.ac.cn>, "sumit.garg@...aro.org" <sumit.garg@...aro.org>,
 "jmorris@...ei.org" <jmorris@...ei.org>
Cc: "Jiang, Dave" <dave.jiang@...el.com>, "linux-integrity@...r.kernel.org"
 <linux-integrity@...r.kernel.org>, "linux-cxl@...r.kernel.org"
 <linux-cxl@...r.kernel.org>, "linux-kernel@...r.kernel.org"
 <linux-kernel@...r.kernel.org>, "keyrings@...r.kernel.org"
 <keyrings@...r.kernel.org>, "linux-security-module@...r.kernel.org"
 <linux-security-module@...r.kernel.org>, "nvdimm@...ts.linux.dev"
 <nvdimm@...ts.linux.dev>
Subject: Re: [PATCH] KEYS: encrypted: Add check for strsep

On Fri Feb 2, 2024 at 12:05 AM UTC, Mimi Zohar wrote:
> On Thu, 2024-02-01 at 23:43 +0200, Jarkko Sakkinen wrote:
> > On Tue Jan 30, 2024 at 8:25 PM EET, Dan Williams wrote:
> > > Jarkko Sakkinen wrote:
> > > > On Tue Jan 30, 2024 at 7:22 PM EET, Jarkko Sakkinen wrote:
> > > > > On Wed Jan 24, 2024 at 11:10 PM EET, Verma, Vishal L wrote:
> > > > > > On Wed, 2024-01-24 at 15:40 -0500, Mimi Zohar wrote:
> > > > > > > On Wed, 2024-01-24 at 20:10 +0000, Verma, Vishal L wrote:
> > > > > > > > Ah, thanks for confirming! Would you like me to send a
> > > > > > > > revert patch or
> > > > > > > > will you do it?
> > > > > > > 
> > > > > > > Revert "KEYS: encrypted: Add check for strsep"
> > > > > > >     
> > > > > > > This reverts commit
> > > > > > > b4af096b5df5dd131ab796c79cedc7069d8f4882.
> > > > > > >     
> > > > > > > New encrypted keys are created either from kernel-generated 
> > > > > > > random
> > > > > > > numbers or user-provided decrypted data.  Revert the change
> > > > > > > requiring
> > > > > > > user-provided decrypted data.
> > > > > > > 
> > > > > > > 
> > > > > > > Can I add your Reported-by?
> > > > > > 
> > > > > > Yes that works, Thank you.
> > > > > 
> > > > > This went totally wrong IMHO.
> > > > > 
> > > > > Priority should be to locate and fix the bug not revert useful
> > > > > stuff
> > > > > when a bug is found that has limited scope.
> > > > 
> > > > By guidelines here the commit is also a bug fix and reverting
> > > > such commit means seeding a bug to the mainline. Also the klog
> > > > message alone is a bug fix here. So also by book it really has
> > > > to come back as it was already commit because we cannot
> > > > knowingly mount bugs to the mainline, right?
> > > 
> > > No, the commit broke userspace. The rule is do not cause
> > > regressions
> > > even if userspace is abusing the ABI in an undesirable way. Even
> > > the
> > > new pr_info() is a log spamming behavior change, a pr_debug() might
> > > be
> > > suitable, but otherwise a logic change here needs a clear
> > > description
> > > about what is broken about the old userspace behavior and why the
> > > kernel
> > > can not possibly safely handle it.
> > 
> > The rationale literally gives empirical proof that the log message
> > is useful by measure. It would be useless if log level is decreased
> > to debug, as then sysadmin's won't take notice. I don't really know
> > what is the definition of "spam" here but at least for me actually
> > useful log message are not in that category.
> > 
> > Issue was legit but git revert is objectively an incorrect way to
> > address the bug.
>
> No, I made a mistake in upstreaming the patch in the first place.  It
> broke the original "encrypted" keys usage.  Reverting it was the
> correct solution.
>
> Mimi

The way I see it the semantic change caused the bug because it was not
backwards compatible. That does not make the log message less useful.

BR, Jarkko