From 2585cd62f0986a6e6d9c83363ed6dbcc66bc9f32 Mon Sep 17 00:00:00 2001 From: Lawrence Brakmo Date: Thu, 25 Jan 2018 16:14:05 -0800 Subject: [PATCH] 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: 40304b2a1567 ("bpf: BPF support for sock_ops") Signed-off-by: Lawrence Brakmo Acked-by: Yuchung Cheng Signed-off-by: Alexei Starovoitov --- net/core/filter.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 18da42a..bf9bb75 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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; -- 2.7.4