From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36A931DDEA; Tue, 27 Aug 2024 15:15:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724771726; cv=none; b=Ap9mYAHI0bO0jXkM9zZ73GcKZc7AokI/KvXlEEegM2xotBl4TzDwMymISkR9uzhWAsQefvgWhRhglqxqiQZedGnTmm0drCPX95vL5oDjuJ5lYEogvd2TRC585B5u8d2GjvalbGO5h+w7a2VOlcnxLa4Gzyt+rAJg2H2rahNwRPA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724771726; c=relaxed/simple; bh=PkugcM2B1c8cPpnAEy8Fb1nyYuk0CvMU7Fa1PDFVEVU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hgLx/Gkn3sm8lHk8n+w+A7BSsNgqsZvbSDOyUjY4mP8poVO3D2kw8sSDATsrxC4X+DANk0mtaITJ3NpLckb/d3RN1vCxmRgFelkoSxzi3hIy+0QVmtvwqOheNfBYzp/PVPAjSwtY7OwHb3DKqc7aZX+jG4Y3uiOKA2RjUjXqWCs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Iyg53KK3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Iyg53KK3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2B66C4DDFF; Tue, 27 Aug 2024 15:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1724771726; bh=PkugcM2B1c8cPpnAEy8Fb1nyYuk0CvMU7Fa1PDFVEVU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Iyg53KK3n3dw/3H+XcRV0uT8WEL7PoLrNs5EMujUWi7aRndqwngUIo+iHNbciWnSF bd/zKb6x7HWPSU2kTolYuJnnC0pQJTg/bC6jIRDRRbgaq3sMYxrIHj44614OgJvrwk Q1pS8ZSBn1J2rKuIVbPBJ2HBa7xA4SpG3dp8cPI0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Biggers , Christian Brauner Subject: [PATCH 6.10 268/273] Revert "pidfd: prevent creation of pidfds for kthreads" Date: Tue, 27 Aug 2024 16:39:52 +0200 Message-ID: <20240827143843.598137619@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240827143833.371588371@linuxfoundation.org> References: <20240827143833.371588371@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner commit 232590ea7fc125986a526e03081b98e5783f70d2 upstream. This reverts commit 3b5bbe798b2451820e74243b738268f51901e7d0. Eric reported that systemd-shutdown gets broken by blocking the creating of pidfds for kthreads as older versions seems to rely on being able to create a pidfd for any process in /proc. Reported-by: Eric Biggers Link: https://lore.kernel.org/r/20240818035818.GA1929@sol.localdomain Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman --- kernel/fork.c | 25 +++---------------------- 1 file changed, 3 insertions(+), 22 deletions(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2069,23 +2069,10 @@ static int __pidfd_prepare(struct pid *p */ int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret) { - if (!pid) - return -EINVAL; - - scoped_guard(rcu) { - struct task_struct *tsk; + bool thread = flags & PIDFD_THREAD; - if (flags & PIDFD_THREAD) - tsk = pid_task(pid, PIDTYPE_PID); - else - tsk = pid_task(pid, PIDTYPE_TGID); - if (!tsk) - return -EINVAL; - - /* Don't create pidfds for kernel threads for now. */ - if (tsk->flags & PF_KTHREAD) - return -EINVAL; - } + if (!pid || !pid_has_task(pid, thread ? PIDTYPE_PID : PIDTYPE_TGID)) + return -EINVAL; return __pidfd_prepare(pid, flags, ret); } @@ -2432,12 +2419,6 @@ __latent_entropy struct task_struct *cop if (clone_flags & CLONE_PIDFD) { int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0; - /* Don't create pidfds for kernel threads for now. */ - if (args->kthread) { - retval = -EINVAL; - goto bad_fork_free_pid; - } - /* Note that no task has been attached to @pid yet. */ retval = __pidfd_prepare(pid, flags, &pidfile); if (retval < 0)