On 06/28/2017 07:31 PM, Lawrence Brakmo wrote:
Added support for calling a subset of socket setsockopts from
BPF_PROG_TYPE_SOCK_OPS programs. The code was duplicated rather
than making the changes to call the socket setsockopt function because
the changes required would have been larger.
The ops supported are:
SO_RCVBUF
SO_SNDBUF
SO_MAX_PACING_RATE
SO_PRIORITY
SO_RCVLOWAT
SO_MARK
Signed-off-by: Lawrence Brakmo <bra...@fb.com>
[...]
@@ -2672,6 +2673,69 @@ static const struct bpf_func_proto
bpf_get_socket_uid_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
+BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
+ int, level, int, optname, char *, optval, int, optlen)
Nit: I would rather make optlen a u32. But more below.
+{
+ struct sock *sk = bpf_sock->sk;
+ int ret = 0;
+ int val;
+
+ if (bpf_sock->is_req_sock)
+ return -EINVAL;
+
+ if (level == SOL_SOCKET) {
if (optlen != sizeof(int))
return -EINVAL;
+ /* Only some socketops are supported */
+ val = *((int *)optval);
+
+ switch (optname) {
+ case SO_RCVBUF:
+ sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
+ sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
+ break;
+ case SO_SNDBUF:
+ sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
+ sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
+ break;
+ case SO_MAX_PACING_RATE:
+ sk->sk_max_pacing_rate = val;
+ sk->sk_pacing_rate = min(sk->sk_pacing_rate,
+ sk->sk_max_pacing_rate);
+ break;
+ case SO_PRIORITY:
+ sk->sk_priority = val;
+ break;
+ case SO_RCVLOWAT:
+ if (val < 0)
+ val = INT_MAX;
+ sk->sk_rcvlowat = val ? : 1;
+ break;
+ case SO_MARK:
+ sk->sk_mark = val;
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ } else if (level == SOL_TCP &&
+ sk->sk_prot->setsockopt == tcp_setsockopt) {
+ /* Place holder */
+ ret = -EINVAL;
+ } else {
+ ret = -EINVAL;
+ }
+ return ret;
+}
+
+static const struct bpf_func_proto bpf_setsockopt_proto = {
+ .func = bpf_setsockopt,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING,
+ .arg4_type = ARG_PTR_TO_MEM,
+ .arg5_type = ARG_CONST_SIZE_OR_ZERO,
Any reason you went with the ARG_CONST_SIZE_OR_ZERO type? Semantics
of this are that allowed [arg4, arg5] pair can be i) [NULL, 0] or
ii) [non-NULL, non-zero], where in case ii) verifier checks that the
area is initialized when coming from BPF stack.
So above 'val = *((int *)optval);' would give a NULL pointer deref
with NULL passed as arg or in case optlen was < sizeof(int) we access
stack out of bounds potentially. If the [NULL, 0] pair is not required,
I would just make that a ARG_CONST_SIZE and then check for size before
accessing optval.
+};
+
static const struct bpf_func_proto *
bpf_base_func_proto(enum bpf_func_id func_id)
{
