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 EF466F9D7; Sat, 3 Feb 2024 04:10:34 +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=1706933435; cv=none; b=PD8yZHXuo7d7BBtBQKwRYkPJi+SVIE6BS1D5oECvm05qGahSkyH4LGKhiczU0dxq4/o8yKTRjX3naQe5Segc65nnDhvsO8g8l91usugruvXRa9T+DhiytwiOIIWnWhCRqPd9bsFmPG73rBq8Xtwk8MvE4bcQ1FHMwsC14+jPo4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706933435; c=relaxed/simple; bh=Cx0AFHUTgGe340ATzUmcfZ+BhxFUHL9QsJ0brBGq8JQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Nl42soFYbWxEdl8o05t0PVutxEhbx7StKD01KXRtjcPGi2GGbBlG/K9Qr4AxKtE5e8ce0HhnYq98ENa0fhp8lbu18cmLppraaYnpXOn6lzTarZlRGIkRZqJnmFsdrRcyq3Uz+r38Bq3VCRYKvO0ST0BEtMd00vPXeXkC0G7+/kU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EUveV5uR; 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="EUveV5uR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4858C433B2; Sat, 3 Feb 2024 04:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1706933434; bh=Cx0AFHUTgGe340ATzUmcfZ+BhxFUHL9QsJ0brBGq8JQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EUveV5uRVUXanpPZBxgI87kSPBCU/lHVcVdq4ktoaER1H9AXGRk8LwAZpZloLGN7s 7OnZE61rW3z9RGEReo8mptGULcM/M7EOk+DaHnVySkQEPfpxZHgTrXMLUyzDqgWoXY smvwDeQC6YtXbFrZupxLJmM3WujDGnc0JbQ/KqRs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Max Kellermann , Tejun Heo , Sasha Levin Subject: [PATCH 6.1 164/219] fs/kernfs/dir: obey S_ISGID Date: Fri, 2 Feb 2024 20:05:37 -0800 Message-ID: <20240203035339.533582198@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240203035317.354186483@linuxfoundation.org> References: <20240203035317.354186483@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ 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 44842e6cf0a9..a00e11ebfa77 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -669,6 +669,18 @@ 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