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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, THOBY Simon <Simon.THOBY@viveris.fr>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Mimi Zohar <zohar@linux.ibm.com>
Subject: [PATCH 5.10 233/236] IMA: remove the dependency on CRYPTO_MD5
Date:   Mon, 13 Sep 2021 15:15:38 +0200
Message-Id: <20210913131108.267650097@linuxfoundation.org>
In-Reply-To: <20210913131100.316353015@linuxfoundation.org>
References: <20210913131100.316353015@linuxfoundation.org>
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From: THOBY Simon <Simon.THOBY@viveris.fr>

commit 8510505d55e194d3f6c9644c9f9d12c4f6b0395a upstream.

MD5 is a weak digest algorithm that shouldn't be used for cryptographic
operation. It hinders the efficiency of a patch set that aims to limit
the digests allowed for the extended file attribute namely security.ima.
MD5 is no longer a requirement for IMA, nor should it be used there.

The sole place where we still use the MD5 algorithm inside IMA is setting
the ima_hash algorithm to MD5, if the user supplies 'ima_hash=md5'
parameter on the command line.  With commit ab60368ab6a4 ("ima: Fallback
to the builtin hash algorithm"), setting "ima_hash=md5" fails gracefully
when CRYPTO_MD5 is not set:
	ima: Can not allocate md5 (reason: -2)
	ima: Allocating md5 failed, going to use default hash algorithm sha256

Remove the CRYPTO_MD5 dependency for IMA.

Signed-off-by: THOBY Simon <Simon.THOBY@viveris.fr>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
[zohar@linux.ibm.com: include commit number in patch description for
stable.]
Cc: stable@vger.kernel.org # 4.17
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 security/integrity/ima/Kconfig |    1 -
 1 file changed, 1 deletion(-)

--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -6,7 +6,6 @@ config IMA
 	select SECURITYFS
 	select CRYPTO
 	select CRYPTO_HMAC
-	select CRYPTO_MD5
 	select CRYPTO_SHA1
 	select CRYPTO_HASH_INFO
 	select TCG_TPM if HAS_IOMEM && !UML