On 23/03/2017 01:27, Chenbo Feng wrote:
> From: Chenbo Feng <fengc@xxxxxxxxxx>
>
> Returns the owner uid of the socket inside a sk_buff. This is useful to
> perform per-UID accounting of network traffic or per-UID packet
> filtering. The socket need to be a fullsock otherwise overflowuid is
> returned.
>
> Signed-off-by: Chenbo Feng <fengc@xxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 9 ++++++++-
> net/core/filter.c | 22 ++++++++++++++++++++++
> tools/include/uapi/linux/bpf.h | 3 ++-
> 3 files changed, 32 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index dc81a9f..ff42111 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -462,6 +462,12 @@ union bpf_attr {
> * @skb: pointer to skb
> * Return: 8 Bytes non-decreasing number on success or 0 if the socket
> * field is missing inside sk_buff
> + *
> + * u32 bpf_get_socket_uid(skb)
> + * Get the owner uid of the socket stored inside sk_buff.
> + * @skb: pointer to skb
> + * Return: uid of the socket owner on success or 0 if the socket pointer
> + * inside sk_buff is NULL
What about UID 0? Why not returning -1 on error?
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -510,7 +516,8 @@ union bpf_attr {
> FN(skb_change_head), \
> FN(xdp_adjust_head), \
> FN(probe_read_str), \
> - FN(get_socket_cookie),
> + FN(get_socket_cookie), \
> + FN(get_socket_uid),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 5b65ae3..93cc4af 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -2612,6 +2612,24 @@ static const struct bpf_func_proto bpf_get_socket_cookie_proto = {
> .arg1_type = ARG_PTR_TO_CTX,
> };
>
> +BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb)
> +{
> + struct sock *sk = sk_to_full_sk(skb->sk);
> + kuid_t kuid;
> +
> + if (!sk || !sk_fullsock(sk))
> + return overflowuid;
> + kuid = sock_net_uid(sock_net(sk), sk);
> + return from_kuid_munged(sock_net(sk)->user_ns, kuid);
> +}
> +
> +static const struct bpf_func_proto bpf_get_socket_uid_proto = {
> + .func = bpf_get_socket_uid,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> static const struct bpf_func_proto *
> bpf_base_func_proto(enum bpf_func_id func_id)
> {
> @@ -2648,6 +2666,8 @@ sk_filter_func_proto(enum bpf_func_id func_id)
> return &bpf_skb_load_bytes_proto;
> case BPF_FUNC_get_socket_cookie:
> return &bpf_get_socket_cookie_proto;
> + case BPF_FUNC_get_socket_uid:
> + return &bpf_get_socket_uid_proto;
> default:
> return bpf_base_func_proto(func_id);
> }
> @@ -2709,6 +2729,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
> return &bpf_skb_under_cgroup_proto;
> case BPF_FUNC_get_socket_cookie:
> return &bpf_get_socket_cookie_proto;
> + case BPF_FUNC_get_socket_uid:
> + return &bpf_get_socket_uid_proto;
> default:
> return bpf_base_func_proto(func_id);
> }
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index a94bdd3..4a2d56d 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -504,7 +504,8 @@ union bpf_attr {
> FN(skb_change_head), \
> FN(xdp_adjust_head), \
> FN(probe_read_str), \
> - FN(get_socket_cookie),
> + FN(get_socket_cookie), \
> + FN(get_socket_uid),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
>
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