Date: Mon, 3 Jun 2019 14:33:47 -0500 From: Kyle Evans <kevans@freebsd.org> To: jail@freebsd.org, James Gritton <jamie@freebsd.org> Subject: Re: svn commit: r348509 - head/lib/libjail Message-ID: <CACNAnaET5zG%2B=do4Z1hN1cq-mj_BryAtScPjVbUFF__AtJd84w@mail.gmail.com> In-Reply-To: <201906021403.x52E3v0x067698@repo.freebsd.org> References: <201906021403.x52E3v0x067698@repo.freebsd.org>
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(Resend to get the list address right- sorry Jamie!) On Sun, Jun 2, 2019 at 9:04 AM Kyle Evans <kevans@freebsd.org> wrote: > > Author: kevans > Date: Sun Jun 2 14:03:56 2019 > New Revision: 348509 > URL: https://svnweb.freebsd.org/changeset/base/348509 > > Log: > jail_getid(3): add special-case immediate return for jid 0 > > As depicted in the comment: jid 0 always exists, but the lookup will fail as > it does not appear in the kernel's alljails list being a special jail. Some > callers will expect/rely on this, and we have no reason to lie because it > does always exist. > > Reported by: Stefan Hegnauer <stefan.hegnauer gmx ch> > MFC after: soon (regression, breaks inspecting jail host bits, partial > revert) > > Modified: > head/lib/libjail/jail_getid.c > > Modified: head/lib/libjail/jail_getid.c > ============================================================================== > --- head/lib/libjail/jail_getid.c Sun Jun 2 09:28:50 2019 (r348508) > +++ head/lib/libjail/jail_getid.c Sun Jun 2 14:03:56 2019 (r348509) > @@ -54,6 +54,15 @@ jail_getid(const char *name) > > jid = strtoul(name, &ep, 10); > if (*name && !*ep) { > + /* > + * jid == 0 is a special case; it will not appear in the > + * kernel's jail list, but naturally processes will be assigned > + * to it because it is prison 0. Trivially return this one > + * without a trip to the kernel, because it always exists but > + * the lookup won't succeed. > + */ > + if (jid == 0) > + return jid; > jiov[0].iov_base = __DECONST(char *, "jid"); > jiov[0].iov_len = sizeof("jid"); > jiov[1].iov_base = &jid; > On a related note- do we have a good reason for not exposing jid 0 via jail_get(2) if that's what's requested and we're operating in prison0? I have no historical context here, so it's not clear to me what issues that might expose other than the issue of exposing a prison that's not all that interesting. Thanks, Kyle Evans
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