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From: David Howells <dhowells@redhat.com>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: dhowells@redhat.com, stephen.smalley.work@gmail.com,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Paul Moore <paul@paul-moore.com>,
	keyrings@vger.kernel.org, selinux@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] keys: Make the KEY_NEED_* perms an enum rather than a mask
Date: Wed, 13 May 2020 23:25:19 +0000	[thread overview]
Message-ID: <3612472.1589412319@warthog.procyon.org.uk> (raw)
In-Reply-To: <004ec27a-cc3a-c75c-952b-ff371b82b8d1@schaufler-ca.com>

Casey Schaufler <casey@schaufler-ca.com> wrote:

> > -	if (perm & ~KEY_NEED_ALL)
> > -		return -EINVAL;
> > +	switch (need_perm) {
> > +	default:
> > +		return -EACCES;
> ...
> Is the change from -EINVAL to -EACCES a bug fix?
> Does it introduce an incompatibility?

It shouldn't happen.  All the actual cases should be covered explicitly in the
switch.  It's to catch a programming issue in the kernel where a new value
gets added to the enum but not propagated to all the places that check for it.

I'd actually prefer it to be something even more obvious, especially as EINVAL
is so widely used in the kernel.  Should I put a WARN_ON in there?

David

WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: Casey Schaufler <casey@schaufler-ca.com>
Cc: dhowells@redhat.com, stephen.smalley.work@gmail.com,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Paul Moore <paul@paul-moore.com>,
	keyrings@vger.kernel.org, selinux@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] keys: Make the KEY_NEED_* perms an enum rather than a mask
Date: Thu, 14 May 2020 00:25:19 +0100	[thread overview]
Message-ID: <3612472.1589412319@warthog.procyon.org.uk> (raw)
In-Reply-To: <004ec27a-cc3a-c75c-952b-ff371b82b8d1@schaufler-ca.com>

Casey Schaufler <casey@schaufler-ca.com> wrote:

> > -	if (perm & ~KEY_NEED_ALL)
> > -		return -EINVAL;
> > +	switch (need_perm) {
> > +	default:
> > +		return -EACCES;
> ...
> Is the change from -EINVAL to -EACCES a bug fix?
> Does it introduce an incompatibility?

It shouldn't happen.  All the actual cases should be covered explicitly in the
switch.  It's to catch a programming issue in the kernel where a new value
gets added to the enum but not propagated to all the places that check for it.

I'd actually prefer it to be something even more obvious, especially as EINVAL
is so widely used in the kernel.  Should I put a WARN_ON in there?

David


  parent reply	other threads:[~2020-05-13 23:25 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-17 15:48 Problem with 9ba09998baa9 ("selinux: Implement the watch_key security hook") in linux-next Paul Moore
2020-04-17 15:48 ` Paul Moore
2020-04-17 16:32 ` Richard Haines
2020-04-17 16:32   ` Richard Haines
2020-04-17 16:59   ` Paul Moore
2020-04-17 16:59     ` Paul Moore
2020-04-21 12:29 ` David Howells
2020-04-21 12:29   ` David Howells
2020-04-22 19:20   ` Paul Moore
2020-04-22 19:20     ` Paul Moore
2020-04-22 21:09     ` Paul Moore
2020-04-22 21:09       ` Paul Moore
2020-04-24 23:43   ` David Howells
2020-04-24 23:43     ` David Howells
2020-04-26 20:53     ` Paul Moore
2020-04-26 20:53       ` Paul Moore
2020-04-27 14:12     ` [PATCH] selinux: Fix use of KEY_NEED_* instead of KEY__* perms David Howells
2020-04-27 14:12       ` David Howells
2020-04-27 14:36       ` Stephen Smalley
2020-04-27 14:36         ` Stephen Smalley
2020-04-27 15:24         ` Paul Moore
2020-04-27 15:24           ` Paul Moore
2020-04-27 17:02       ` Stephen Smalley
2020-04-27 17:02         ` Stephen Smalley
2020-04-27 22:17         ` Paul Moore
2020-04-27 22:17           ` Paul Moore
2020-04-28 12:54 ` [PATCH] selinux: Fix use of KEY_NEED_* instead of KEY__* perms [v2] David Howells
2020-04-28 12:54   ` David Howells
2020-04-28 14:32   ` Stephen Smalley
2020-04-28 14:32     ` Stephen Smalley
2020-04-28 15:57   ` David Howells
2020-04-28 15:57     ` David Howells
2020-04-28 16:19     ` Stephen Smalley
2020-04-28 16:19       ` Stephen Smalley
2020-05-01 16:37       ` Paul Moore
2020-05-01 16:37         ` Paul Moore
2020-05-12 22:33       ` [PATCH] keys: Make the KEY_NEED_* perms an enum rather than a mask David Howells
2020-05-12 22:33         ` David Howells
2020-05-13  1:04         ` Paul Moore
2020-05-13  1:04           ` Paul Moore
2020-05-13 12:58         ` Stephen Smalley
2020-05-13 12:58           ` Stephen Smalley
2020-05-13 15:25         ` Casey Schaufler
2020-05-13 15:25           ` Casey Schaufler
2020-05-13 23:13         ` David Howells
2020-05-13 23:13           ` David Howells
2020-05-14 12:08           ` Stephen Smalley
2020-05-14 12:08             ` Stephen Smalley
2020-05-14 14:45             ` Stephen Smalley
2020-05-14 14:45               ` Stephen Smalley
2020-05-13 23:16         ` David Howells
2020-05-13 23:16           ` David Howells
2020-05-13 23:25         ` David Howells [this message]
2020-05-13 23:25           ` David Howells
2020-05-14 11:00         ` Jarkko Sakkinen
2020-05-14 11:00           ` Jarkko Sakkinen
2020-05-14 16:58         ` [PATCH] keys: Move permissions checking decisions into the checking code David Howells
2020-05-14 16:58           ` David Howells
2020-05-14 17:06           ` Casey Schaufler
2020-05-14 17:06             ` Casey Schaufler
2020-05-15 15:06           ` Stephen Smalley
2020-05-15 15:06             ` Stephen Smalley
2020-05-15 16:45           ` David Howells
2020-05-15 16:45             ` David Howells
2020-05-15 18:55             ` Stephen Smalley
2020-05-15 18:55               ` Stephen Smalley
2020-05-15 19:10               ` Casey Schaufler
2020-05-15 19:10                 ` Casey Schaufler
2020-05-15 22:27             ` David Howells
2020-05-15 22:27               ` David Howells

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