Date: Tue, 14 Mar 2023 20:33:10 +0100
From: hubert depesz lubaczewski <depesz@depesz.com>
Sender: depesz@depesz.com
To: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Subject: pg_read_server_files doesn't let me use pg_ls_dir() or pg_read_file?
Message-ID: <ZBDL9gMrc0/fjrLU@depesz.com>
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Hi,
Tested it now on built today Pg 16devel, straight from repo.

In docs (https://www.postgresql.org/docs/current/functions-admin.html#FUNCTIONS-ADMIN-GENFILE), I found:
> The functions shown in Table 9.99 provide native access to files on
> the machine hosting the server. Only files within the database cluster
> directory and the log_directory can be accessed, unless the user is
> a superuser or is granted the role pg_read_server_files. Use
> a relative path for files in the cluster directory, and a path
> matching the log_directory configuration setting for log files.

which I understand that if I'll grant pg_read_server_files to some user,
then this user should be able to use the generic file access functions.

So I tried:

#v+
$ select current_user;
 current_user
──────────────
 test
(1 row)

$ \du+ test
                                            List of roles
 Role name │ Attributes │                           Member of                           │ Description
───────────┼────────────┼───────────────────────────────────────────────────────────────┼─────────────
 test      │            │ {pg_read_all_settings,pg_read_all_stats,pg_read_server_files} │

$ select * from pg_ls_dir('.');
ERROR:  permission denied for function pg_ls_dir

$ select * from pg_ls_dir('log');
ERROR:  permission denied for function pg_ls_dir

$ select * from pg_ls_dir('/etc');
ERROR:  permission denied for function pg_ls_dir

$ select * from pg_read_file('PG_VERSION');
ERROR:  permission denied for function pg_read_file

$ select * from pg_read_file('/etc/passwd');
ERROR:  permission denied for function pg_read_file
#v-

After I additionally granted EXECUTE on the functions, I was able to run them, even when I revoked pg_read_server_files.

Am I missing something in there, or is this a bug?

Best regards,

depesz