Re: [PATCH bpf-next v8 04/12] bpf: Only reply field should be writeable

On 1/24/18 11:58 AM, Yuchung Cheng wrote:

On Tue, Jan 23, 2018 at 11:57 PM, Lawrence Brakmo [off-list ref] wrote:

quoted

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 ?

yes. we will send it to 4.15 and 4.14 as soon as it's released.
See discussion with Eric.

quoted

Fixes: 40304b2a1567 ("bpf: BPF support for sock_ops")
Signed-off-by: Lawrence Brakmo <redacted>

Acked-by: Yuchung Cheng <redacted>

quoted

---
 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