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From:   Mark O'Donovan <shiftee@posteo.net>
To:     linux-kernel@vger.kernel.org
Cc:     linux-nvme@lists.infradead.org, sagi@grimberg.me, hch@lst.de,
        axboe@kernel.dk, kbusch@kernel.org, hare@suse.de,
        Mark O'Donovan <shiftee@posteo.net>,
        Akash Appaiah <Akash.Appaiah@dell.com>
Subject: [PATCH v5 3/3] nvme-auth: allow mixing of secret and hash lengths
Date:   Tue, 17 Oct 2023 17:09:19 +0000
Message-Id: <20231017170919.30358-4-shiftee@posteo.net>
In-Reply-To: <20231017170919.30358-1-shiftee@posteo.net>
References: <20231017170919.30358-1-shiftee@posteo.net>
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We can now use any of the secret transformation hashes with a
secret, regardless of the secret size.
e.g. a 32 byte key with the SHA-512(64 byte) hash.

The example secret from the spec should now be permitted with
any of the following:
DHHC-1:00:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:01:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:02:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:
DHHC-1:03:ia6zGodOr4SEG0Zzaw398rpY0wqipUWj4jWjUh4HWUz6aQ2n:

Note: Secrets are still restricted to 32,48 or 64 bits.

Co-developed-by: Akash Appaiah <Akash.Appaiah@dell.com>
Signed-off-by: Akash Appaiah <Akash.Appaiah@dell.com>
Signed-off-by: Mark O'Donovan <shiftee@posteo.net>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 drivers/nvme/common/auth.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c
index f954aeb647a5..a8e87dfbeab2 100644
--- a/drivers/nvme/common/auth.c
+++ b/drivers/nvme/common/auth.c
@@ -190,14 +190,6 @@ struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret,
 		goto out_free_secret;
 	}
 
-	if (key_hash > 0 &&
-	    (key_len - 4) != nvme_auth_hmac_hash_len(key_hash)) {
-		pr_err("Mismatched key len %d for %s\n", key_len,
-		       nvme_auth_hmac_name(key_hash));
-		ret = -EINVAL;
-		goto out_free_secret;
-	}
-
 	/* The last four bytes is the CRC in little-endian format */
 	key_len -= 4;
 	/*
-- 
2.39.2