linux-kernel - Re: [PATCH] KEYS: encrypted: fix key instantiation with user-provided data

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Message-ID: <53730789a41358673b1715dd650706e9ffcb1199.camel@linux.ibm.com>
Date:   Tue, 20 Sep 2022 10:43:14 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Nikolaus Voss <nv@...n.de>, David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>
Cc:     linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yael Tzur <yaelt@...gle.com>
Subject: Re: [PATCH] KEYS: encrypted: fix key instantiation with
 user-provided data

On Fri, 2022-09-16 at 07:45 +0200, Nikolaus Voss wrote:
> Commit cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-provided
> decrypted data") added key instantiation with user provided decrypted data.
> The user data is hex-ascii-encoded but was just memcpy'ed to the binary buffer.
> Fix this to use hex2bin instead.

Thanks, Nikolaus.  We iterated a number of times over what would be the
safest userspace input.  One of the last changes was that the key data
should be hex-ascii-encoded.  Unfortunately, the LTP
testcases/kernel/syscalls/keyctl09.c example isn't hex-ascii-encoded
and the example in Documentation/security/keys/trusted-encrypted.rst
just cat's a file.  Both expect the length to be the length of the
userspace provided data.   With this patch, when hex2bin() fails, there
is no explanation.

-- 
thanks,

Mimi