From: Dan Williams <dan.j.williams@intel.com>
To: James Bottomley <jejb@linux.ibm.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
Roberto Sassu <roberto.sassu@huawei.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mimi Zohar <zohar@linux.ibm.com>,
David Howells <dhowells@redhat.com>,
keyrings@vger.kernel.org
Subject: Re: [PATCH] security/keys/trusted: Allow operation without hardware TPM
Date: Tue, 19 Mar 2019 18:55:59 -0700 [thread overview]
Message-ID: <CAPcyv4hXKQcdLnKG6rPNOJr2wjq31uCCr+16S5Yu6S5A_5UGrA@mail.gmail.com> (raw)
In-Reply-To: <1552956989.2785.31.camel@linux.ibm.com>
On Mon, Mar 18, 2019 at 5:56 PM James Bottomley <jejb@linux.ibm.com> wrote:
>
> On Mon, 2019-03-18 at 17:30 -0700, Dan Williams wrote:
> > On Mon, Mar 18, 2019 at 5:24 PM James Bottomley <jejb@linux.ibm.com>
> > wrote:
> > >
> > > On Mon, 2019-03-18 at 16:45 -0700, Dan Williams wrote:
> > > > Rather than fail initialization of the trusted.ko module, arrange
> > > > for the module to load, but rely on trusted_instantiate() to fail
> > > > trusted-key operations.
> > >
> > > What actual problem is this fixing? To me it would seem like an
> > > enhancement to make the trusted module fail at load time if there's
> > > no TPM rather than waiting until first use to find out it can never
> > > work. Is there some piece of user code that depends on the
> > > successful insertion of trusted.ko?
> >
> > The module dependency chain relies on it. If that can be broken that
> > would also be an acceptable fix.
> >
> > I found this through the following dependency chain: libnvdimm.ko ->
> > encrypted_keys.ko -> trusted.ko.
> >
> > "key_type_trusted" is the symbol that encrypted_keys needs regardless
> > of whether the tpm is present.
>
> That's a nasty dependency caused by every key type module exporting a
> symbol for its key type. It really seems that key types should be
> looked up by name not symbol to prevent more of these dependency issues
> from spreading. Something like this (untested and definitely won't
> work without doing an EXPORT_SYMBOL on key_type_lookup).
>
> If it does look acceptable we can also disentangle the nasty module
> dependencies in the encrypted key code around masterkey which alone
> should be a huge improvement because that code is too hacky to live.
>
> James
>
> ---
> diff --git a/security/keys/encrypted-keys/masterkey_trusted.c b/security/keys/encrypted-keys/masterkey_trusted.c
> index dc3d18cae642..b98416f091e2 100644
> --- a/security/keys/encrypted-keys/masterkey_trusted.c
> +++ b/security/keys/encrypted-keys/masterkey_trusted.c
> @@ -19,6 +19,7 @@
> #include <keys/trusted-type.h>
> #include <keys/encrypted-type.h>
> #include "encrypted.h"
> +#include "../internal.h"
>
> /*
> * request_trusted_key - request the trusted key
> @@ -32,8 +33,14 @@ struct key *request_trusted_key(const char *trusted_desc,
> {
> struct trusted_key_payload *tpayload;
> struct key *tkey;
> + struct key_type *type;
>
> - tkey = request_key(&key_type_trusted, trusted_desc, NULL);
> + type = key_type_lookup("trusted");
> + if (IS_ERR(type)) {
> + tkey = (struct key *)type;
> + goto error;
> + }
> + tkey = request_key(type, trusted_desc, NULL);
> if (IS_ERR(tkey))
> goto error;
This falls over with the need to pin the module while any key that
needs service from the hosting key_type operations might be live in
the system.
I could hang a "struct module *" off of the key_type so the host
module can be pinned, but that requires teaching all consumers of the
key_type module lifetime. Not impossible, but I think too big for a
fix, and I'd rather go with this local fixup to drop the dependency on
tpm_default_chip() successfully enumerating a TPM.
next prev parent reply other threads:[~2019-03-20 1:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-18 23:45 [PATCH] security/keys/trusted: Allow operation without hardware TPM Dan Williams
2019-03-19 0:24 ` James Bottomley
2019-03-19 0:30 ` Dan Williams
2019-03-19 0:56 ` James Bottomley
2019-03-19 1:34 ` Dan Williams
2019-03-20 1:55 ` Dan Williams [this message]
2019-03-20 2:19 ` James Bottomley
2019-03-19 22:56 ` Mimi Zohar
2019-03-19 23:01 ` Dan Williams
2019-03-21 13:54 ` Jarkko Sakkinen
2019-03-21 14:26 ` Roberto Sassu
2019-03-21 16:30 ` Dan Williams
2019-03-21 17:45 ` Roberto Sassu
2019-03-22 10:12 ` Jarkko Sakkinen
2019-03-22 15:24 ` Dan Williams
2019-03-25 14:12 ` Jarkko Sakkinen
2019-03-25 14:50 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAPcyv4hXKQcdLnKG6rPNOJr2wjq31uCCr+16S5Yu6S5A_5UGrA@mail.gmail.com \
--to=dan.j.williams@intel.com \
--cc=dhowells@redhat.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=jejb@linux.ibm.com \
--cc=keyrings@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
--cc=roberto.sassu@huawei.com \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).