From nobody Fri Dec 19 19:54:41 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 35A2F21A44A; Mon, 31 Mar 2025 14:32:37 +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=1743431557; cv=none; b=fkIhQO1ujETJ2c6KIMt3eigNRcer+9KgKXKlNEJVzTti1Ot2J7yFlxDl+VJHG98ihldP45W/KoMDBw+1gTWMsDYBkvIc6So/p9dQ38SZMmxlFxY3ZzlxkOlLvRo/q/4spykxIvmd2v6HjNXOZaAmc/mqEpJFLzwddSOBHxEIWcQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743431557; c=relaxed/simple; bh=zORTvlJlx+KkHe9iE94PcQMRLf91J3RmqhTq+NrHcuc=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=uWBonV202xZP8Nzh7wZFyomNKpe6vSn06diR08p3GibS4KfUslF+AcaOuUwHS9K1+c/Wj08qiPxzEea7tZM9L+7W6FWgGbFlQwGt/wKlguKUHhSSefFVvDHqopJIPKEs2TEGxR8GjZJ71ntlIzU/7VRclSxzCA0YeNh7QRuadcI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=I0ce2Nax; 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="I0ce2Nax" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 228E1C4CEE3; Mon, 31 Mar 2025 14:32:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743431557; bh=zORTvlJlx+KkHe9iE94PcQMRLf91J3RmqhTq+NrHcuc=; h=From:To:Cc:Subject:Date:From; b=I0ce2NaxfAUE+95c2CalerRnYZYJ/LQRXtaEntm11+ElidZ6iEgyvEUdoccGxM/Yz cEWk6CVYAFYqoQLEKatEopkOp4+MHPpZqUAK8rwE4KM0FxMxdCqfFiHtBCnaE8lOdg DIraEJvuHZcZ+llv5pxMdJNCsdB1bqas8AcvXkQp5EBvHDE52IPajtFzSpJNmwyc7A W+M1qZsAIgJsPw19uuOfbpkbz8jdQGK96jQJxKhBOIOB4rjPVPNbVSZGC9YLO/fTgE F4/ut5NK/PS4v3ocu6bVjqjP6gazGpeP87B73KDCI1bEPiVL9pYL1Cx27tkBgcPkbN zx61MRMB63ODQ== 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 5.10] umount: Allow superblock owners to force umount Date: Mon, 31 Mar 2025 10:32:34 -0400 Message-Id: <20250331143234.1667913-1-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 5.10.235 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 7e67db7456b3d..2f97112657adc 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1716,6 +1716,7 @@ static inline bool may_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; @@ -1725,7 +1726,7 @@ 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