linux-kernel - [PATCH 01/24] bpfilter: reject kernel addresses

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Date:   Mon, 20 Jul 2020 14:47:14 +0200
From:   Christoph Hellwig <hch@....de>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        linux-sctp@...r.kernel.org, linux-hams@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, bridge@...ts.linux-foundation.org,
        linux-can@...r.kernel.org, dccp@...r.kernel.org,
        linux-decnet-user@...ts.sourceforge.net,
        linux-wpan@...r.kernel.org, linux-s390@...r.kernel.org,
        mptcp@...ts.01.org, lvs-devel@...r.kernel.org,
        rds-devel@....oracle.com, linux-afs@...ts.infradead.org,
        tipc-discussion@...ts.sourceforge.net, linux-x25@...r.kernel.org
Subject: [PATCH 01/24] bpfilter: reject kernel addresses

When feeding addresses to userspace we can't support kernel addresses
that were fed under set_fs(KERNEL_DS) from bpf-cgroup.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 net/bpfilter/bpfilter_kern.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/bpfilter/bpfilter_kern.c b/net/bpfilter/bpfilter_kern.c
index 2c31e82cb953af..977e9dad72ca4f 100644
--- a/net/bpfilter/bpfilter_kern.c
+++ b/net/bpfilter/bpfilter_kern.c
@@ -41,6 +41,11 @@ static int __bpfilter_process_sockopt(struct sock *sk, int optname,
 	ssize_t n;
 	int ret = -EFAULT;
 
+	if (uaccess_kernel()) {
+		pr_err("kernel access not supported\n");
+		return -EFAULT;
+	}
+
 	req.is_set = is_set;
 	req.pid = current->pid;
 	req.cmd = optname;
-- 
2.27.0