From nobody Fri Dec 19 19:56:48 2025 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 A4FC12144C1; Mon, 31 Mar 2025 14:32:34 +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=1743431554; cv=none; b=J3Fw1e6WJ1V1Z3ZUU6YGyAmKPw6BoyQahu3BI1EJq18Ege06gDftQc2ZFmJKmkf4w3qX2Q7Cttl9fllIu/a5B5Z55t6bClP+b64lVDJzBEuLkLgGTvN0+SkISxcJOoj7HUMu4GuQhsR97UKpJQFWmcv/pAggqjl/BK814NdUDy8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743431554; c=relaxed/simple; bh=NPMu5PMOc2IS2Cbsuk893FEO4aCVyIvnT+PYZF8LVlk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=hSTJg9mS4+k4xzdCzjcxdHjyYGhEFClzKjVAdGOvYYR3j0edXkn+sfTbZX8UfZPo1FXaz5WXYRYfUOZGQzV+96pbJcDoM9mfseyVkuv0NwQd3lSkYm5l8dJvkHir73oFR8XZLnS6ZzC99KzFemX9hNbFUfp9GtkiK5Pyop0c8Ds= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XB7WSdXp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XB7WSdXp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38BCAC4CEE3; Mon, 31 Mar 2025 14:32:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743431554; bh=NPMu5PMOc2IS2Cbsuk893FEO4aCVyIvnT+PYZF8LVlk=; h=From:To:Cc:Subject:Date:From; b=XB7WSdXpEpx65ST4Ebd3RbB1NORz4hTLN368ms92xvIS5Ao+xcHayd2cSCrIpsbbZ QGcWvwnY8QiBOKpFrtJuJcQyygvipU0AOVWOIQ9CIy0Ot27kpCFuiC/okWJ0iQhu++ 7HllqZFUdCr1wyxdIn8ACD4ao9CWO1KiHk0qqvtqiXHEWv0Jcuo9fhIcGKeUH0w/IF rfB5pHqoCkcsbSfRjxs1XEMuLzMKmUlSFYG1IUyxJC0r7ULk+dlggu13S2Xprt4Cuv XPdrCL//fAOt3YtWGtrckRllTVAj2Sn3ueedWlMYyYbNlRQRgZO2XS6MGj2uD1/H5d 5GzKntabjx36g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Trond Myklebust , "Eric W. Biederman" , Christian Brauner , Sasha Levin , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 5.15] umount: Allow superblock owners to force umount Date: Mon, 31 Mar 2025 10:32:31 -0400 Message-Id: <20250331143231.1667887-1-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.179 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Trond Myklebust [ Upstream commit e1ff7aa34dec7e650159fd7ca8ec6af7cc428d9f ] Loosen the permission check on forced umount to allow users holding CAP_SYS_ADMIN privileges in namespaces that are privileged with respect to the userns that originally mounted the filesystem. Signed-off-by: Trond Myklebust Link: https://lore.kernel.org/r/12f212d4ef983714d065a6bb372fbb378753bf4c.17= 42315194.git.trond.myklebust@hammerspace.com Acked-by: "Eric W. Biederman" Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/namespace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index 22af4b6c737f4..642baef4d9aaa 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1734,6 +1734,7 @@ static void warn_mandlock(void) static int can_umount(const struct path *path, int flags) { struct mount *mnt =3D real_mount(path->mnt); + struct super_block *sb =3D path->dentry->d_sb; =20 if (!may_mount()) return -EPERM; @@ -1743,7 +1744,7 @@ static int can_umount(const struct path *path, int fl= ags) return -EINVAL; if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ return -EINVAL; - if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) + if (flags & MNT_FORCE && !ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) return -EPERM; return 0; } --=20 2.39.5