diff mbox

[net-next,v6,2/3] Add a eBPF helper function to retrieve socket uid

Message ID 1490069337-14076-3-git-send-email-chenbofeng.kernel@gmail.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Chenbo Feng March 21, 2017, 4:08 a.m. UTC 
From: Chenbo Feng <fengc@google.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. The socket need to be a fullsock otherwise overflowuid is
returned.

Signed-off-by: Chenbo Feng <fengc@google.com>
---
 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(-)

Comments

Alexei Starovoitov March 21, 2017, 5:40 a.m. UTC | #1 
On Mon, Mar 20, 2017 at 09:08:56PM -0700, Chenbo Feng wrote:
> From: Chenbo Feng <fengc@google.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. The socket need to be a fullsock otherwise overflowuid is
> returned.
> 
> Signed-off-by: Chenbo Feng <fengc@google.com>

Acked-by: Alexei Starovoitov <ast@kernel.org>
Lorenzo Colitti March 21, 2017, 7 a.m. UTC | #2 
On Tue, Mar 21, 2017 at 1:08 PM, Chenbo Feng
<chenbofeng.kernel@gmail.com> wrote:
> +       if (!sk || !sk_fullsock(sk))
> +               return overflowuid;
> +       kuid = sock_net_uid(sock_net(sk), sk);
> +       return from_kuid_munged(current_user_ns(), kuid);

Is current_user_ns() correct in all the contexts you'll want to run
this code from? For packets sent by userspace applications it's likely
to be correct, but what about received packets, and packets processed
by the xt_ebpf module?
diff mbox

Patch

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
  */
 #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..2f022df 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(current_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