From: ebiederm@xmission.com (Eric W. Biederman)
To: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux Containers <containers@lists.linux-foundation.org>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Jann Horn <jannh@google.com>, Jens Axboe <axboe@kernel.dk>,
Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v9 4/8] Reimplement RLIMIT_NPROC on top of ucounts
Date: Wed, 07 Apr 2021 11:56:36 -0500 [thread overview]
Message-ID: <m1eefmjanv.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20210406154444.icpvezlq3izzxf5t@example.org> (Alexey Gladkov's message of "Tue, 6 Apr 2021 17:44:44 +0200")
Alexey Gladkov <gladkov.alexey@gmail.com> writes:
> On Mon, Apr 05, 2021 at 11:56:35AM -0500, Eric W. Biederman wrote:
>>
>> Also when setting ns->ucount_max[] in create_user_ns because one value
>> is signed and the other is unsigned. Care should be taken so that
>> rlimit_infinity is translated into the largest positive value the
>> type can hold.
>
> You mean like that ?
>
> ns->ucount_max[UCOUNT_RLIMIT_NPROC] = rlimit(RLIMIT_NPROC) <= LONG_MAX ?
> rlimit(RLIMIT_NPROC) : LONG_MAX;
> ns->ucount_max[UCOUNT_RLIMIT_MSGQUEUE] = rlimit(RLIMIT_MSGQUEUE) <= LONG_MAX ?
> rlimit(RLIMIT_MSGQUEUE) : LONG_MAX;
> ns->ucount_max[UCOUNT_RLIMIT_SIGPENDING] = rlimit(RLIMIT_SIGPENDING) <= LONG_MAX ?
> rlimit(RLIMIT_SIGPENDING) : LONG_MAX;
> ns->ucount_max[UCOUNT_RLIMIT_MEMLOCK] = rlimit(RLIMIT_MEMLOCK) <= LONG_MAX ?
> rlimit(RLIMIT_MEMLOCK) : LONG_MAX;
Yes.
I only got as far as:
if (rlimit(RLIMI_NNN) == RLIM_INFINITY) {
ns->ucount_max[UCOUNT_LIMIT_NNN] = LONG_MAX;
} else {
ns->ucount_max[UCOUNT_LMIT_NNN] = rlmit(RLIMIT_NNN);
}
But forcing everything about LONG_MAX to LONG_MAX actually looks better
in practice. Especially as that is effectively RLIMIT_INFINITY anyway.
Eric
next prev parent reply other threads:[~2021-04-07 16:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 20:59 [PATCH v9 0/8] Count rlimits in each user namespace Alexey Gladkov
2021-03-23 20:59 ` [PATCH v9 1/8] Increase size of ucounts to atomic_long_t Alexey Gladkov
2021-03-23 20:59 ` [PATCH v9 2/8] Add a reference to ucounts for each cred Alexey Gladkov
2021-03-23 20:59 ` [PATCH v9 3/8] Use atomic_t for ucounts reference counting Alexey Gladkov
2021-04-05 17:01 ` Eric W. Biederman
2021-03-23 20:59 ` [PATCH v9 4/8] Reimplement RLIMIT_NPROC on top of ucounts Alexey Gladkov
2021-04-05 16:56 ` Eric W. Biederman
2021-04-06 15:44 ` Alexey Gladkov
2021-04-07 16:56 ` Eric W. Biederman [this message]
2021-03-23 20:59 ` [PATCH v9 5/8] Reimplement RLIMIT_MSGQUEUE " Alexey Gladkov
2021-03-23 20:59 ` [PATCH v9 6/8] Reimplement RLIMIT_SIGPENDING " Alexey Gladkov
2021-04-05 16:58 ` Eric W. Biederman
2021-03-23 20:59 ` [PATCH v9 7/8] Reimplement RLIMIT_MEMLOCK " Alexey Gladkov
2021-03-23 20:59 ` [PATCH v9 8/8] kselftests: Add test to check for rlimit changes in different user namespaces Alexey Gladkov
2021-04-05 17:03 ` [PATCH v9 0/8] Count rlimits in each user namespace Eric W. Biederman
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