Re: [PATCH bpf-next v8 04/12] bpf: Only reply field should be writeable
From: Yuchung Cheng <hidden>
Date: 2018-01-24 19:59:11
On Tue, Jan 23, 2018 at 11:57 PM, Lawrence Brakmo [off-list ref] wrote:
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.
Would this patch be more suitable for -net ?
Fixes: 40304b2a1567 ("bpf: BPF support for sock_ops")
Signed-off-by: Lawrence Brakmo <redacted>Acked-by: Yuchung Cheng <redacted>
quoted hunk ↗ jump to hunk
--- 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 0cf170f..c356ec0 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; --2.9.5