Re: allowing privileges on untrusted languages
От | Kohei KaiGai |
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Тема | Re: allowing privileges on untrusted languages |
Дата | |
Msg-id | CADyhKSUXXVbswozzfP7ZCAyfx9La6q-HWvnu43Xemjz4Z+XOxQ@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: allowing privileges on untrusted languages (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: allowing privileges on untrusted languages
(Robert Haas <robertmhaas@gmail.com>)
|
Список | pgsql-hackers |
2013/1/20 Tom Lane <tgl@sss.pgh.pa.us>: > Robert Haas <robertmhaas@gmail.com> writes: >> Yeah. We'd need to think a little bit about how to make this work, >> since I think that adding a gajillion booleans to pg_authid will not >> make anyone very happy. But I like the idea. GRANT >> kill_sessions_of_other_users TO bob? GRANT install_untrusted_pls TO >> any_database_owner? GRANT install_an_extension_called(hstore) TO >> any_database_owner? I know there are other ways of doing all of these >> things, so don't take the specific proposals too seriously, but we >> clearly have a need to parcel out controlled bits of the superuser >> mojo to individual users in a nice, clean, convenient way. Getting >> agreement on the details is likely to be difficult, but it seems like >> a good concept from 10,000 feet. > > The traditional answer to that, which not only can be done already in > all existing releases but is infinitely more flexible than any > hard-wired scheme we could implement, is that you create superuser-owned > security-definer functions that can execute any specific operation you > want to allow, and then GRANT EXECUTE on those functions to just the > people who should have it. > I also agree it is a right solution to provide unprivileged users a trusted way to handle privileged operations, as set-uid programs are widely utilized for same purpose on operating system, however, it needs to satisfy an assumption these trusted procedures have to be free from bugs and vulnerabilities. In general, it is not an easy assumption. Thus, it is the reason why fine-grained capability is preferred than root as single-point-of-failure on security. For example, now /bin/ping has no set-uid bit on recent Fedora system, to avoid a risk when this program has any vulnerability. [kaigai@iwashi ~]$ ls -l /bin/ping -rwxr-xr-x. 1 root root 40880 Dec 7 15:19 /bin/ping [kaigai@iwashi ~]$ getcap /bin/ping/bin/ping = cap_net_admin,cap_net_raw+ep I think, our situation is similar. If DBA is not 100% certain on safeness of self-defined functions, I believe he want unprivileged users to call security-definer functions owned by limited capable user, instead of fully capable superuser. I'm not positive to over-interpret this concept, like hundred of capabilities being nightmare of maintenance. However, it is worthwhile as basis of self-defined security-definer functions. I'd like people to imagine a case when trusted procedures were buggy. Thanks, -- KaiGai Kohei <kaigai@kaigai.gr.jp>
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