bpf: Fix tcp_clamp_kern.c sample program

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

Fixes: 390ee7e29fc8 ("bpf: enforce return code for cgroup-bpf programs")
Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 11 deletions

diff --git a/samples/bpf/tcp_clamp_kern.c b/samples/bpf/tcp_clamp_kern.c
index d68eadd9ca2d..f4225c9d2c0c 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;