Add a eBPF helper function to retrieve socket uid

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 <[email protected]> Signed-off-by: David S. Miller <[email protected]>
torvalds · Mar 24, 2017 · 6acc5c2 · 6acc5c2
1 parent 91b8270
commit 6acc5c2
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Showing 3 changed files with 32 additions and 2 deletions.
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
@@ -465,6 +465,12 @@ 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), \
@@ -513,7 +519,8 @@ 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
@@ -2619,6 +2619,24 @@ 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)
 {
@@ -2655,6 +2673,8 @@ 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);
  }
@@ -2716,6 +2736,8 @@ 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
@@ -507,7 +507,8 @@ 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