From: ebiederm@xmission.com (Eric W. Biederman)
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
James Morris <jmorris@namei.org>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>,
Seth Forshee <seth.forshee@canonical.com>,
Dongsu Park <dongsu@kinvolk.io>, Alban Crequy <alban@kinvolk.io>
Subject: Re: [PATCH v1 1/2] ima: fail signature verification on untrusted filesystems
Date: Mon, 26 Feb 2018 20:12:55 -0600 [thread overview]
Message-ID: <87606jw57c.fsf@xmission.com> (raw)
In-Reply-To: <1519255954.3400.16.camel@linux.vnet.ibm.com> (Mimi Zohar's message of "Wed, 21 Feb 2018 18:32:34 -0500")
Mimi Zohar <zohar@linux.vnet.ibm.com> writes:
> On Wed, 2018-02-21 at 17:12 -0600, Eric W. Biederman wrote:
>>
>> As I understand the second scenario SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> is set, which implies that the filesystem is lacking something for IMA
>> to reliably know when a file has changed. AKA a technical deficiency.
>>
>> The fourth scenario is the case when SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> can be legitimately be cleared, because the filesystem provides all
>> of the necessary support for IMA to reliably know when a file has
>> changed.
>
> The information might be there, but IMA currently detects a file
> change and resets the flags only when the last writer calls
> __fput(). Any other time, new support would be needed.
My point was only that for local NTFS or local exFAT with a quality
and trusted fuse implementation they should be as safe in this regard
as any other filesystem. So in theory we could have fuse implementing
this level of filesystem as well. Not that I suggest we try for that
out of the gate.
Thank you very much for the clarification about the last fput that helps
me understand SB_I_IMA_UNVERIFIEDABLE_SIGNATURES much better.
Eric
WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v1 1/2] ima: fail signature verification on untrusted filesystems
Date: Mon, 26 Feb 2018 20:12:55 -0600 [thread overview]
Message-ID: <87606jw57c.fsf@xmission.com> (raw)
In-Reply-To: <1519255954.3400.16.camel@linux.vnet.ibm.com> (Mimi Zohar's message of "Wed, 21 Feb 2018 18:32:34 -0500")
Mimi Zohar <zohar@linux.vnet.ibm.com> writes:
> On Wed, 2018-02-21 at 17:12 -0600, Eric W. Biederman wrote:
>>
>> As I understand the second scenario SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> is set, which implies that the filesystem is lacking something for IMA
>> to reliably know when a file has changed. AKA a technical deficiency.
>>
>> The fourth scenario is the case when SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> can be legitimately be cleared, because the filesystem provides all
>> of the necessary support for IMA to reliably know when a file has
>> changed.
>
> The information might be there, but IMA currently detects a file
> change and resets the flags only when the last writer calls
> __fput().??Any other time, new support would be needed.
My point was only that for local NTFS or local exFAT with a quality
and trusted fuse implementation they should be as safe in this regard
as any other filesystem. So in theory we could have fuse implementing
this level of filesystem as well. Not that I suggest we try for that
out of the gate.
Thank you very much for the clarification about the last fput that helps
me understand SB_I_IMA_UNVERIFIEDABLE_SIGNATURES much better.
Eric
--
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: ebiederm@xmission.com (Eric W. Biederman)
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
James Morris <jmorris@namei.org>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Miklos Szeredi <miklos@szeredi.hu>,
Seth Forshee <seth.forshee@canonical.com>,
Dongsu Park <dongsu@kinvolk.io>, Alban Crequy <alban@kinvolk.io>
Subject: Re: [PATCH v1 1/2] ima: fail signature verification on untrusted filesystems
Date: Mon, 26 Feb 2018 20:12:55 -0600 [thread overview]
Message-ID: <87606jw57c.fsf@xmission.com> (raw)
In-Reply-To: <1519255954.3400.16.camel@linux.vnet.ibm.com> (Mimi Zohar's message of "Wed, 21 Feb 2018 18:32:34 -0500")
Mimi Zohar <zohar@linux.vnet.ibm.com> writes:
> On Wed, 2018-02-21 at 17:12 -0600, Eric W. Biederman wrote:
>>
>> As I understand the second scenario SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> is set, which implies that the filesystem is lacking something for IMA
>> to reliably know when a file has changed. AKA a technical deficiency.
>>
>> The fourth scenario is the case when SB_I_IMA_UNVERIFIABLE_SIGNATURES
>> can be legitimately be cleared, because the filesystem provides all
>> of the necessary support for IMA to reliably know when a file has
>> changed.
>
> The information might be there, but IMA currently detects a file
> change and resets the flags only when the last writer calls
> __fput(). Any other time, new support would be needed.
My point was only that for local NTFS or local exFAT with a quality
and trusted fuse implementation they should be as safe in this regard
as any other filesystem. So in theory we could have fuse implementing
this level of filesystem as well. Not that I suggest we try for that
out of the gate.
Thank you very much for the clarification about the last fput that helps
me understand SB_I_IMA_UNVERIFIEDABLE_SIGNATURES much better.
Eric
next prev parent reply other threads:[~2018-02-27 2:13 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-19 15:18 [PATCH v1 0/2] ima: untrusted filesystems Mimi Zohar
2018-02-19 15:18 ` Mimi Zohar
2018-02-19 15:18 ` [PATCH v1 1/2] ima: fail signature verification on " Mimi Zohar
2018-02-19 15:18 ` Mimi Zohar
2018-02-19 21:47 ` Eric W. Biederman
2018-02-19 21:47 ` Eric W. Biederman
2018-02-20 0:52 ` James Morris
2018-02-20 0:52 ` James Morris
2018-02-20 2:02 ` Eric W. Biederman
2018-02-20 2:02 ` Eric W. Biederman
2018-02-20 14:02 ` Mimi Zohar
2018-02-20 14:02 ` Mimi Zohar
2018-02-20 14:02 ` Mimi Zohar
2018-02-20 20:16 ` Serge E. Hallyn
2018-02-20 20:16 ` Serge E. Hallyn
2018-02-20 20:16 ` Serge E. Hallyn
2018-02-21 14:46 ` Mimi Zohar
2018-02-21 14:46 ` Mimi Zohar
2018-02-21 14:46 ` Mimi Zohar
2018-02-21 22:46 ` Eric W. Biederman
2018-02-21 22:46 ` Eric W. Biederman
2018-02-21 22:46 ` Eric W. Biederman
2018-02-21 22:57 ` Mimi Zohar
2018-02-21 22:57 ` Mimi Zohar
2018-02-21 22:57 ` Mimi Zohar
2018-02-21 23:12 ` Eric W. Biederman
2018-02-21 23:12 ` Eric W. Biederman
2018-02-21 23:12 ` Eric W. Biederman
2018-02-21 23:32 ` Mimi Zohar
2018-02-21 23:32 ` Mimi Zohar
2018-02-21 23:32 ` Mimi Zohar
2018-02-27 2:12 ` Eric W. Biederman [this message]
2018-02-27 2:12 ` Eric W. Biederman
2018-02-27 2:12 ` Eric W. Biederman
2018-02-21 22:53 ` Eric W. Biederman
2018-02-21 22:53 ` Eric W. Biederman
2018-02-21 22:53 ` Eric W. Biederman
2018-02-21 23:03 ` Mimi Zohar
2018-02-21 23:03 ` Mimi Zohar
2018-02-21 23:03 ` Mimi Zohar
2018-02-19 22:50 ` kbuild test robot
2018-02-19 22:50 ` kbuild test robot
2018-02-19 22:50 ` kbuild test robot
2018-02-19 23:36 ` kbuild test robot
2018-02-19 23:36 ` kbuild test robot
2018-02-19 23:36 ` kbuild test robot
2018-02-19 15:18 ` [PATCH v1 2/2] fuse: define the filesystem as untrusted Mimi Zohar
2018-02-19 15:18 ` Mimi Zohar
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=87606jw57c.fsf@xmission.com \
--to=ebiederm@xmission.com \
--cc=alban@kinvolk.io \
--cc=dongsu@kinvolk.io \
--cc=jmorris@namei.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=miklos@szeredi.hu \
--cc=serge@hallyn.com \
--cc=seth.forshee@canonical.com \
--cc=zohar@linux.vnet.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.