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Date: Thu, 02 Feb 2017 22:32:55 +0100
From: Daniel Borkmann <daniel@...earbox.net>
To: Chenbo Feng <chenbofeng.kernel@...il.com>,
"David S . Miller" <davem@...emloft.net>,
Alexei Starovoitov <ast@...com>, netdev@...r.kernel.org
CC: Willem de Bruijn <willemb@...gle.com>,
Lorenzo Colitti <lorenzo@...gle.com>,
Chenbo Feng <fengc@...gle.com>
Subject: Re: [PATCH net-next 2/2] Add a eBPF helper function to retrieve socket
uid
On 02/02/2017 09:59 PM, Chenbo Feng wrote:
> From: Chenbo Feng <fengc@...gle.com>
>
> 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.
>
> Signed-off-by: Chenbo Feng <chenbofeng.kernel@...il.com>
> ---
> include/linux/bpf.h | 1 +
> include/uapi/linux/bpf.h | 9 ++++++++-
> net/core/filter.c | 19 +++++++++++++++++++
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 3f2e0af28c6e..c775ca4678b7 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -350,6 +350,7 @@ extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
> extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
> extern const struct bpf_func_proto bpf_get_stackid_proto;
> extern const struct bpf_func_proto bpf_get_socket_cookie_proto;
> +extern const struct bpf_func_proto bpf_get_socket_uid_proto;
Likewise, no need to add it here.
> /* Shared helpers among cBPF and eBPF. */
> void bpf_user_rnd_init_once(void);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 62ee5fab08e5..dad4dc7aca49 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -436,6 +436,12 @@ 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
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -483,7 +489,8 @@ union bpf_attr {
> FN(get_numa_node_id), \
> FN(skb_change_head), \
> FN(xdp_adjust_head), \
> - 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 913b14d3b484..bc36ed72551f 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -2610,6 +2610,23 @@ 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;
> + kuid_t kuid;
Nit: already init them above.
> + sk = skb->sk;
> + kuid = sock_net_uid(dev_net(skb->dev), sk);
Don't you need to test for fullsock? Do you mean something like below?
struct sock *sk = skb->sk;
kuid_t kuid = sock_net_uid(net, sk && sk_fullsock(sk) ?
sk : NULL);
> + return (u32)kuid.val;
> +}
> +
> +const struct bpf_func_proto bpf_get_socket_uid_proto = {
static ...
> + .func = bpf_get_socket_uid,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> static const struct bpf_func_proto *
> sk_filter_func_proto(enum bpf_func_id func_id)
> {
> @@ -2635,6 +2652,8 @@ sk_filter_func_proto(enum bpf_func_id func_id)
> return bpf_get_trace_printk_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 NULL;
> }
>
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