From: Eric Biggers <ebiggers3@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@google.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
David Safford <safford@us.ibm.com>
Subject: Re: [PATCH 3/5] KEYS: encrypted: sanitize all key material
Date: Fri, 21 Apr 2017 11:24:18 -0700 [thread overview]
Message-ID: <20170421182418.GA12755@gmail.com> (raw)
In-Reply-To: <28373.1492785068@warthog.procyon.org.uk>
On Fri, Apr 21, 2017 at 03:31:08PM +0100, David Howells wrote:
> Eric Biggers <ebiggers3@gmail.com> wrote:
>
> > - memzero_explicit(epayload->decrypted_data, epayload->decrypted_datalen);
> > - kfree(key->payload.data[0]);
> > + kzfree(key->payload.data[0]);
>
> Should kzfree() be using memzero_explicit() rather than memset()?
>
> David
It's not actually needed because it's impossible for the compiler to optimize
away the memset(). memzero_explicit() is only needed on stack data.
The reason I still used memzero_explicit() for heap data in a couple of my
patches, even though it's unnecessary, is just that it makes it clearer that
it's being done for sanitization purposes, as opposed to some random memset.
That's not as much of an issue for kzfree(), since it's explicitly for
sanitization purposes already.
As a separate note, something that might make sense at some point would be to
skip the memset in kzfree() if slab poisoning is enabled.
Eric
WARNING: multiple messages have this Message-ID (diff)
From: ebiggers3@gmail.com (Eric Biggers)
To: linux-security-module@vger.kernel.org
Subject: [PATCH 3/5] KEYS: encrypted: sanitize all key material
Date: Fri, 21 Apr 2017 11:24:18 -0700 [thread overview]
Message-ID: <20170421182418.GA12755@gmail.com> (raw)
In-Reply-To: <28373.1492785068@warthog.procyon.org.uk>
On Fri, Apr 21, 2017 at 03:31:08PM +0100, David Howells wrote:
> Eric Biggers <ebiggers3@gmail.com> wrote:
>
> > - memzero_explicit(epayload->decrypted_data, epayload->decrypted_datalen);
> > - kfree(key->payload.data[0]);
> > + kzfree(key->payload.data[0]);
>
> Should kzfree() be using memzero_explicit() rather than memset()?
>
> David
It's not actually needed because it's impossible for the compiler to optimize
away the memset(). memzero_explicit() is only needed on stack data.
The reason I still used memzero_explicit() for heap data in a couple of my
patches, even though it's unnecessary, is just that it makes it clearer that
it's being done for sanitization purposes, as opposed to some random memset.
That's not as much of an issue for kzfree(), since it's explicitly for
sanitization purposes already.
As a separate note, something that might make sense at some point would be to
skip the memset in kzfree() if slab poisoning is enabled.
Eric
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next prev parent reply other threads:[~2017-04-21 18:24 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-21 8:30 [PATCH 0/5] KEYS: sanitize key payloads Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 1/5] KEYS: sanitize add_key() and keyctl() " Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-28 17:57 ` Eric Biggers
2017-04-28 17:57 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 2/5] KEYS: user_defined: sanitize " Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 3/5] KEYS: encrypted: sanitize all key material Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 4/5] KEYS: trusted: " Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-21 8:30 ` [PATCH 5/5] KEYS: sanitize key structs before freeing Eric Biggers
2017-04-21 8:30 ` Eric Biggers
2017-04-21 13:57 ` [PATCH 2/5] KEYS: user_defined: sanitize key payloads David Howells
2017-04-21 13:57 ` David Howells
2017-04-21 18:34 ` Eric Biggers
2017-04-21 18:34 ` Eric Biggers
2017-04-24 14:14 ` David Howells
2017-04-24 14:14 ` David Howells
2017-04-21 14:31 ` [PATCH 3/5] KEYS: encrypted: sanitize all key material David Howells
2017-04-21 14:31 ` David Howells
2017-04-21 18:24 ` Eric Biggers [this message]
2017-04-21 18:24 ` Eric Biggers
2017-04-24 14:14 ` David Howells
2017-04-24 14:14 ` David Howells
2017-04-27 15:09 ` [PATCH 0/5] KEYS: sanitize key payloads David Howells
2017-04-27 15:09 ` David Howells
2017-04-27 17:43 ` Eric Biggers
2017-04-27 17:43 ` Eric Biggers
2017-06-02 15:34 ` [PATCH 1/5] KEYS: sanitize add_key() and keyctl() " David Howells
2017-06-02 15:34 ` David Howells
2017-06-02 15:34 ` David Howells
2017-06-02 17:24 ` Eric Biggers
2017-06-02 17:24 ` Eric Biggers
2017-06-02 17:24 ` Eric Biggers
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