On 6/30/17, 5:01 PM, "Daniel Borkmann" <dan...@iogearbox.net> wrote:
On 06/30/2017 10:06 PM, Lawrence Brakmo wrote:
[...]
> @@ -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)
> +{
> + struct sock *sk = bpf_sock->sk;
> + int ret = 0;
> + int val;
> +
> + if (!sk_fullsock(sk))
> + return -EINVAL;
> +
> + if (level == SOL_SOCKET) {
> + /* 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,
Hm, I had some feedback on this in your last revision of the patch
set [1] that a NULL pointer dereference can be triggered here. Probably
oversaw it; I mentioned wrt the above:
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.
Would be good if you could still address it in a most likely final respin.
Thanks,
Daniel
Working on it, will have it soon. Thanks for all the feedback!
[1]
https://urldefense.proofpoint.com/v2/url?u=http-3A__patchwork.ozlabs.org_patch_781800_&d=DwIC-g&c=5VD0RTtNlTh3ycd41b3MUw&r=pq_Mqvzfy-C8ltkgyx1u_g&m=6nijuGf2vMueVsU1CETOPc1IB9xCd3ApP5vUppoXe_A&s=l4VJ1IUAA1qjTa0fMvOxsKRdoa361lM65q5QGKteEMw&e=
