From: Aleksa Sarai <asarai@suse.de>
To: Aleksa Sarai <cyphar@cyphar.com>
Cc: Sargun Dhillon <sargun@sargun.me>,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
containers@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, christian.brauner@ubuntu.com
Subject: Re: [PATCH 3/4] seccomp: Add SECCOMP_USER_NOTIF_FLAG_PIDFD to get pidfd on listener trap
Date: Sun, 26 Jan 2020 15:14:39 +1100 [thread overview]
Message-ID: <20200126041439.liwfmb4h74zmhi76@yavin.dot.cyphar.com> (raw)
In-Reply-To: <20200126040325.5eimmm7hli5qcqrr@yavin.dot.cyphar.com>
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On 2020-01-26, Aleksa Sarai <cyphar@cyphar.com> wrote:
> On 2020-01-24, Sargun Dhillon <sargun@sargun.me> wrote:
> > static long seccomp_notify_recv(struct seccomp_filter *filter,
> > void __user *buf)
> > {
> > struct seccomp_knotif *knotif = NULL, *cur;
> > struct seccomp_notif unotif;
> > + struct task_struct *group_leader;
> > + bool send_pidfd;
> > ssize_t ret;
> >
> > + if (copy_from_user(&unotif, buf, sizeof(unotif)))
> > + return -EFAULT;
> > /* Verify that we're not given garbage to keep struct extensible. */
> > - ret = check_zeroed_user(buf, sizeof(unotif));
> > - if (ret < 0)
> > - return ret;
> > - if (!ret)
> > + if (unotif.id ||
> > + unotif.pid ||
> > + memchr_inv(&unotif.data, 0, sizeof(unotif.data)) ||
> > + unotif.pidfd)
> > + return -EINVAL;
>
> IMHO this check is more confusing than the original check_zeroed_user().
> Something like the following is simpler and less prone to forgetting to
> add a new field in the future:
>
> if (memchr_inv(&unotif, 0, sizeof(unotif)))
> return -EINVAL;
Also the check in the patch doesn't ensure that any unnamed padding is
zeroed -- memchr_inv(&unotif, 0, sizeof(unotif)) does.
--
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>
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next prev parent reply other threads:[~2020-01-26 4:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-24 9:17 [PATCH 0/4] Add the ability to get a pidfd on seccomp user notifications Sargun Dhillon
2020-01-24 9:17 ` [PATCH 1/4] pid: Add pidfd_create_file helper Sargun Dhillon
2020-01-24 9:17 ` [PATCH 2/4] fork: Use newly created " Sargun Dhillon
2020-01-24 9:17 ` [PATCH 3/4] seccomp: Add SECCOMP_USER_NOTIF_FLAG_PIDFD to get pidfd on listener trap Sargun Dhillon
2020-01-24 18:03 ` Tycho Andersen
2020-01-24 20:09 ` Sargun Dhillon
2020-01-26 4:10 ` Aleksa Sarai
2020-01-26 5:42 ` Tycho Andersen
[not found] ` <CAMp4zn_Xv2iicmH2Nc4-EZceD7T8AFe9PQRNX4bNEiAuoKs+vA@mail.gmail.com>
2020-05-15 11:58 ` Christian Brauner
2020-01-26 4:03 ` Aleksa Sarai
2020-01-26 4:14 ` Aleksa Sarai [this message]
2020-01-27 5:06 ` Sargun Dhillon
2020-01-24 9:17 ` [PATCH 4/4] selftests/seccomp: test SECCOMP_USER_NOTIF_FLAG_PIDFD Sargun Dhillon
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