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 EEF436086D; Sun, 28 Jan 2024 16:13:33 +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=1706458414; cv=none; b=lLXKT2bUeLaxuqgWxaqt8y9MzfpqUm6225aGO+GOVjn44BWXjePd8lz9EK9tEm6HkCbPBUzIRIwSNzbsLOWsoAQjpjcby+Vu4DfnNYg+sEGjDBt2r7X+/esbpKbUX9CJrYMiOqJPqahoEgObAlRNSELU/zKrRsPfPVNCq8//jtY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706458414; c=relaxed/simple; bh=uMnD0aUO2l3M2khXx2m/8Vx9nla+p5h2CdRabr2cOEM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i0gGvrX/FVnj+K32mV+jF5lAFyK/wFvvAsoBF3GXjayOlZZDyXOwcFQqDJON3xvMBDBgwodP8DJItRDkx9lB8M5Ep/Vfl0EgqC0MQZBX62uEpVnMfosFjZ77nU43d8vAb2MH3kMA195dNLdfmBz+9IRPsDUCVQ9wbWDyxuOvEXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RdCFNJED; 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="RdCFNJED" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF01BC43399; Sun, 28 Jan 2024 16:13:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706458413; bh=uMnD0aUO2l3M2khXx2m/8Vx9nla+p5h2CdRabr2cOEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RdCFNJEDpD11hDgNXw4uPDRcIm+A8+O4e3dLdiKKrD+0dKCnFS19RMF3nkzT58xBr LTzBbEwiN01/Y6/XuWDr/vBDb3JyY8bt9HEErvcgrKKpwdh2SP7H9cSn7xC2CDofzB tUDpwU/za4qA2cBx5PQWbQdGff0zI32c/nOIlfaR43geIx9UxSmKNTEvsyN46rWq3n zTi8l+PsVp65tAKCOvCtQkRAj8BnO3XtlZFXZCeS+g1b+Ojr+VNUYURiLnFJpA2Ex6 8tl1aiQkSDHvAwC/mqKZ0nlhDpIdSLnDZFrY15lZTDa9GFiA7RlKFl8fLj7L0QcHE+ wzEDEw0erzhtA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Max Kellermann , Tejun Heo , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 6.6 10/31] fs/kernfs/dir: obey S_ISGID Date: Sun, 28 Jan 2024 11:12:40 -0500 Message-ID: <20240128161315.201999-10-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240128161315.201999-1-sashal@kernel.org> References: <20240128161315.201999-1-sashal@kernel.org> 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 6.6.14 Content-Transfer-Encoding: 8bit From: Max Kellermann [ Upstream commit 5133bee62f0ea5d4c316d503cc0040cac5637601 ] Handling of S_ISGID is usually done by inode_init_owner() in all other filesystems, but kernfs doesn't use that function. In kernfs, struct kernfs_node is the primary data structure, and struct inode is only created from it on demand. Therefore, inode_init_owner() can't be used and we need to imitate its behavior. S_ISGID support is useful for the cgroup filesystem; it allows subtrees managed by an unprivileged process to retain a certain owner gid, which then enables sharing access to the subtree with another unprivileged process. -- v1 -> v2: minor coding style fix (comment) Signed-off-by: Max Kellermann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20231208093310.297233-2-max.kellermann@ionos.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- fs/kernfs/dir.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 8b2bd65d70e7..62d39ecf0a46 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -676,6 +676,18 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, { struct kernfs_node *kn; + if (parent->mode & S_ISGID) { + /* this code block imitates inode_init_owner() for + * kernfs + */ + + if (parent->iattr) + gid = parent->iattr->ia_gid; + + if (flags & KERNFS_DIR) + mode |= S_ISGID; + } + kn = __kernfs_new_node(kernfs_root(parent), parent, name, mode, uid, gid, flags); if (kn) { -- 2.43.0