Date: Thu, 10 Dec 2020 20:32:39 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Neil Chen <carpenter.nail.cz@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Subject: Re: Proposed patch for key managment
Message-ID: <20201211013239.GD13515@momjian.us>
References: <20201202213814.GG20285@momjian.us>
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On Thu, Dec 10, 2020 at 07:26:48PM +0800, Neil Chen wrote:
> 
> 
>     Hi, everyone
> 
>     I have read the patch and did some simple tests. I'm not entirely sure
>     about some code segments; e.g.:
> 
>     In the BootStrapKmgr() we generate a data encryption key by:
>     key = generate_crypto_key(file_encryption_keylen);
> 
>     However, I found that the file_encryption_keylen is always 0 in bootstrap
>     mode because there exitst another variable bootstrap_file_encryption_keylen
>     in xlog.c and bootstrap.c.

Oh, good point;  that is very helpful.  I was relying on SetConfigOption
to set file_encryption_keylen, but that happens _after_ we create the
keys, so they were zero length.  I have fixed this by passing
bootstrap_file_encryption_keylen to the boot routines.  The diff URL has
the fix:

	https://github.com/postgres/postgres/compare/master...bmomjian:key.diff

>     We get the REL/WAL key by KmgrGetKey() call and it works like:
>     return (const CryptoKey *) &(KmgrShmem->intlKeys[id]);
> 
>     But in bootstrap mode, the KmgrShmem are not assigned. So, if we want to
>     use it to encrypt something in bootstrap mode, I suggest we make the
>     following changes:
>     if ( in bootstrap mode)
>     return intlKeys[id]; // a static variable which contains key
>     else
>     reutrn (const CryptoKey *) &(KmgrShmem->intlKeys[id]);

Yes, you are also correct here.  I had not gotten to using KmgrGetKey
yet, but it clearly needs your suggestion, so have done that.

Thanks for your help.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee