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 8EAC67BAFF; Wed, 21 Feb 2024 14:05:32 +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=1708524332; cv=none; b=gHf1w+XEBbUubc+PsnAyO61MAcIVzCqRSqzx27aVJRQV6OBDJPb/1/2WRrNlSRMVvVAvihasaWci5kVb/lEHk+Vphpcvaxb4gkr4hwooXkHnRdWDHDq+Z9OCcE/sHwaMYga+mJ6nspx5SH1oWwGEItLSyOKDd1DDY2XK/Bw0pa4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708524332; c=relaxed/simple; bh=9HZpis6lv8YmpC9Hc7qOPdw4K1fnXERP72Q9iUn06Eg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NbbYBVEFSCy6vrQ6TYnmG1AFTKbUEcPkHcVQkIjx8URkpkmKSOxUN2j+qo3OsEPnG03TsKA95jihiu4iLyrYDl2kz5sn8MhuJ+j/83VsoF65M+icMH9RWTYVeXxb1c7Of3uejYU7MRJn+JdG2od6R39j/Pr7hRw8d+BGFURS2e8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JPyFjSRC; 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="JPyFjSRC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEF72C433F1; Wed, 21 Feb 2024 14:05:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708524332; bh=9HZpis6lv8YmpC9Hc7qOPdw4K1fnXERP72Q9iUn06Eg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JPyFjSRC2sOKyDcy8h8mvDTiif1mQsxLgATW8llWbdyooPtiKbFdJ40v4rSbUk2kK o3c2UAIuVLEDhew/4T5eWKDqrpGNIHhAC3PJ1NNtf3AOR6Ood3zC6wy/vZ5PUmr9lJ L6HNCqJFoOqab9R1kOFsPIqdN18PtkYnJt0Cw+vE= 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 5.10 211/379] fs/kernfs/dir: obey S_ISGID Date: Wed, 21 Feb 2024 14:06:30 +0100 Message-ID: <20240221130001.141936820@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240221125954.917878865@linuxfoundation.org> References: <20240221125954.917878865@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-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 c91ee05cce74..0ba056e06e48 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -696,6 +696,18 @@ 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