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Date: Thu, 22 Jan 2026 00:51:12 +0000
From: Eric Biggers <ebiggers@kernel.org>
To: Benjamin Coddington <bcodding@hammerspace.com>
Cc: Chuck Lever <chuck.lever@oracle.com>, Jeff Layton <jlayton@kernel.org>,
	NeilBrown <neil@brown.name>, Trond Myklebust <trondmy@kernel.org>,
	Anna Schumaker <anna@kernel.org>,
	Rick Macklem <rick.macklem@gmail.com>, linux-nfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: Re: [PATCH v2 1/3] NFSD: Add a key for signing filehandles
Message-ID: <20260122005112.GA946159@google.com>
References: <cover.1769026777.git.bcodding@hammerspace.com>
 <6d7bfccbaf082194ea257749041c19c2c2385cce.1769026777.git.bcodding@hammerspace.com>
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In-Reply-To: <6d7bfccbaf082194ea257749041c19c2c2385cce.1769026777.git.bcodding@hammerspace.com>

On Wed, Jan 21, 2026 at 03:24:16PM -0500, Benjamin Coddington wrote:
> +		sip_fh_key = kmalloc(sizeof(siphash_key_t), GFP_KERNEL);
> +		if (!sip_fh_key) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
> +
> +		memcpy(sip_fh_key, &uuid_fh_key, sizeof(siphash_key_t));

Note that siphash_key_t consists of a pair of native-endian u64's:

    typedef struct {
            u64 key[2];
    } siphash_key_t;

If you copy a byte array into it, the result will differ on little
endian vs. big endian CPUs.

You may want to do le64_to_cpus() on each u64, like what
fscrypt_derive_siphash_key() does.

- Eric