[PATCH net-next 6/6] bpf: Fix tcp_clamp_kern.c sample program

[Lawrence Brakmo]

The program was returning -1 in some cases which is not allowed
by the verifier any longer.

Fixes: 6c4a01b27852 ("bpf: Sample bpf program to set sndcwnd clamp")
Signed-off-by: Lawrence Brakmo <bra...@fb.com>
---
 samples/bpf/tcp_clamp_kern.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/samples/bpf/tcp_clamp_kern.c b/samples/bpf/tcp_clamp_kern.c
index d68eadd9..f4225c9 100644
--- a/samples/bpf/tcp_clamp_kern.c
+++ b/samples/bpf/tcp_clamp_kern.c
@@ -41,8 +41,10 @@ int bpf_clamp(struct bpf_sock_ops *skops)
        /* For testing purposes, only execute rest of BPF program
         * if neither port numberis 55601
         */
-       if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 
55601)
-               return -1;
+       if (bpf_ntohl(skops->remote_port) != 55601 && skops->local_port != 
55601) {
+               skops->reply = -1;
+               return 0;
+       }
 
        op = (int) skops->op;
 
@@ -66,9 +68,9 @@ int bpf_clamp(struct bpf_sock_ops *skops)
                        /* Set sndbuf and rcvbuf of active connections */
                        rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF,
                                            &bufsize, sizeof(bufsize));
-                       rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET,
-                                                     SO_RCVBUF, &bufsize,
-                                                     sizeof(bufsize));
+                       rv += bpf_setsockopt(skops, SOL_SOCKET,
+                                            SO_RCVBUF, &bufsize,
+                                            sizeof(bufsize));
                        break;
                case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
                        rv = bpf_setsockopt(skops, SOL_TCP,
@@ -80,12 +82,12 @@ int bpf_clamp(struct bpf_sock_ops *skops)
                        rv = bpf_setsockopt(skops, SOL_TCP,
                                            TCP_BPF_SNDCWND_CLAMP,
                                            &clamp, sizeof(clamp));
-                       rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET,
-                                                     SO_SNDBUF, &bufsize,
-                                                     sizeof(bufsize));
-                       rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET,
-                                                     SO_RCVBUF, &bufsize,
-                                                     sizeof(bufsize));
+                       rv += bpf_setsockopt(skops, SOL_SOCKET,
+                                            SO_SNDBUF, &bufsize,
+                                            sizeof(bufsize));
+                       rv += bpf_setsockopt(skops, SOL_SOCKET,
+                                            SO_RCVBUF, &bufsize,
+                                            sizeof(bufsize));
                        break;
                default:
                        rv = -1;
-- 
2.9.5