Commit 2585cd62 authored Jan 25, 2018 by Lawrence Brakmo Committed by Alexei Starovoitov Jan 25, 2018

bpf: Only reply field should be writeable



Currently, a sock_ops BPF program can write the op field and all the
reply fields (reply and replylong). This is a bug. The op field should
not have been writeable and there is currently no way to use replylong
field for indices >= 1. This patch enforces that only the reply field
(which equals replylong[0]) is writeable.

Fixes: 40304b2a ("bpf: BPF support for sock_ops")
Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent e9dcd80b

net/core/filter.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -3845,8 +3845,7 @@ static bool sock_ops_is_valid_access(int off, int size,
		{
		if (type == BPF_WRITE) {
		switch (off) {
		case offsetof(struct bpf_sock_ops, op) ...
		offsetof(struct bpf_sock_ops, replylong[3]):
		case offsetof(struct bpf_sock_ops, reply):
		break;
		default:
		return false;