From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35A2EC43616 for ; Mon, 10 May 2021 13:06:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 233766128D for ; Mon, 10 May 2021 13:06:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351267AbhEJNFu (ORCPT ); Mon, 10 May 2021 09:05:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38254 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350814AbhEJNBg (ORCPT ); Mon, 10 May 2021 09:01:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620651631; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qYJxIj3byUuRfvoDwZxiPqSPDM85oniejzPazMGcaYc=; b=RkC4jKzyt8Wt09Wa3ReD71zDL0zrO6OGvAayvoq1tczOp8Vi3ysZz+ozSZxpqZelMWlr0i +6oDMW03u1edBjsCIo0yRwnYA0nvz/oc95BV01Swuxfdlh+zIN8IXcC2YmVSr8jywH0By1 +LWZnbofJXy+KCTjtgZJO/ewy/A9JHg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-175-t8T9_VgtNmieHN64DMH8Zg-1; Mon, 10 May 2021 09:00:29 -0400 X-MC-Unique: t8T9_VgtNmieHN64DMH8Zg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8E485107ACFB; Mon, 10 May 2021 13:00:28 +0000 (UTC) Received: from lithium.homenet.telecomitalia.it (ovpn-115-83.ams2.redhat.com [10.36.115.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0321F60FC2; Mon, 10 May 2021 13:00:19 +0000 (UTC) From: Giuseppe Scrivano To: linux-kernel@vger.kernel.org Cc: serge@hallyn.com, dwalsh@redhat.com, christian.brauner@ubuntu.com, ebiederm@xmission.com Subject: [RFC PATCH 2/3] getgroups: hide unknown groups Date: Mon, 10 May 2021 15:00:10 +0200 Message-Id: <20210510130011.1441834-3-gscrivan@redhat.com> In-Reply-To: <20210510130011.1441834-1-gscrivan@redhat.com> References: <20210510130011.1441834-1-gscrivan@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org do not copy to userspace the groups that are not known in the namespace. Signed-off-by: Giuseppe Scrivano --- kernel/groups.c | 40 +++++++++++++++++++-------------------- kernel/uid16.c | 50 ++++++++++++++++++++++++------------------------- 2 files changed, 44 insertions(+), 46 deletions(-) diff --git a/kernel/groups.c b/kernel/groups.c index f0c3b49da19e..97fa9faa7813 100644 --- a/kernel/groups.c +++ b/kernel/groups.c @@ -35,19 +35,30 @@ EXPORT_SYMBOL(groups_free); /* export the group_info to a user-space array */ static int groups_to_user(gid_t __user *grouplist, - const struct group_info *group_info) + const struct group_info *group_info, + int gidsetsize) { struct user_namespace *user_ns = current_user_ns(); - int i; unsigned int count = group_info->ngroups; + int i, ngroups = 0; for (i = 0; i < count; i++) { gid_t gid; - gid = from_kgid_munged(user_ns, group_info->gid[i]); - if (put_user(gid, grouplist+i)) - return -EFAULT; + gid = from_kgid(user_ns, group_info->gid[i]); + if (gid == (gid_t)-1) { + if (user_ns->flags & USERNS_SETGROUPS_SHADOW) + continue; + gid = overflowgid; + } + if (gidsetsize) { + if (ngroups == gidsetsize) + return -EINVAL; + if (put_user(gid, grouplist + ngroups)) + return -EFAULT; + } + ngroups++; } - return 0; + return ngroups; } /* fill a group_info from a user-space array - it must be allocated already */ @@ -146,26 +157,13 @@ EXPORT_SYMBOL(set_current_groups); SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) { + /* no need to grab task_lock here; it cannot change */ const struct cred *cred = current_cred(); - int i; if (gidsetsize < 0) return -EINVAL; - /* no need to grab task_lock here; it cannot change */ - i = cred->group_info->ngroups; - if (gidsetsize) { - if (i > gidsetsize) { - i = -EINVAL; - goto out; - } - if (groups_to_user(grouplist, cred->group_info)) { - i = -EFAULT; - goto out; - } - } -out: - return i; + return groups_to_user(grouplist, cred->group_info, gidsetsize); } bool may_setgroups(struct group_info **shadowed_groups) diff --git a/kernel/uid16.c b/kernel/uid16.c index cb1110f083ce..6f2dc793b5f8 100644 --- a/kernel/uid16.c +++ b/kernel/uid16.c @@ -112,21 +112,33 @@ SYSCALL_DEFINE1(setfsgid16, old_gid_t, gid) } static int groups16_to_user(old_gid_t __user *grouplist, - struct group_info *group_info) + struct group_info *group_info, + int gidsetsize) { struct user_namespace *user_ns = current_user_ns(); - int i; - old_gid_t group; - kgid_t kgid; + unsigned int count = group_info->ngroups; + int i, ngroups = 0; - for (i = 0; i < group_info->ngroups; i++) { - kgid = group_info->gid[i]; - group = high2lowgid(from_kgid_munged(user_ns, kgid)); - if (put_user(group, grouplist+i)) - return -EFAULT; + for (i = 0; i < count; i++) { + gid_t gid; + old_gid_t group; + + gid = from_kgid(user_ns, group_info->gid[i]); + if (gid == (gid_t)-1) { + if (user_ns->flags & USERNS_SETGROUPS_SHADOW) + continue; + gid = overflowgid; + } + group = high2lowgid(gid); + if (gidsetsize) { + if (ngroups == gidsetsize) + return -EINVAL; + if (put_user(group, grouplist + ngroups)) + return -EFAULT; + } + ngroups++; } - - return 0; + return ngroups; } static int groups16_from_user(struct group_info *group_info, @@ -153,25 +165,13 @@ static int groups16_from_user(struct group_info *group_info, SYSCALL_DEFINE2(getgroups16, int, gidsetsize, old_gid_t __user *, grouplist) { + /* no need to grab task_lock here; it cannot change */ const struct cred *cred = current_cred(); - int i; if (gidsetsize < 0) return -EINVAL; - i = cred->group_info->ngroups; - if (gidsetsize) { - if (i > gidsetsize) { - i = -EINVAL; - goto out; - } - if (groups16_to_user(grouplist, cred->group_info)) { - i = -EFAULT; - goto out; - } - } -out: - return i; + return groups16_to_user(grouplist, cred->group_info, gidsetsize); } SYSCALL_DEFINE2(setgroups16, int, gidsetsize, old_gid_t __user *, grouplist) -- 2.31.1