Re: [PATCH net-next v2 2/2] Add a eBPF helper function to retrieve socket uid

[Eric Dumazet]

On Sun, 2017-02-05 at 18:17 -0800, Chenbo Feng wrote:
> From: Chenbo Feng 
> 
> 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 
> ---
> +BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb)
> +{
> + struct sock *sk = skb->sk;
> + kuid_t kuid = sock_net_uid(net, sk && sk_fullsock(sk) ?
> +sk : NULL);
> + return (u32)kuid.val;
> +}
> +

Have you considered to use sk_to_full_sk() ?

struct sock *sk = sk_to_full_sk(skb->sk);
kuid_t kuid = sock_net_uid(net, sk);

Re: [PATCH net-next v2 2/2] Add a eBPF helper function to retrieve socket uid

[kbuild test robot]

Hi Chenbo,

[auto build test ERROR on net-next/master]

url:
https://github.com/0day-ci/linux/commits/Chenbo-Feng/Two-Helper-function-about-socket-information/20170206-102835
config: x86_64-randconfig-x014-201706 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64 

All errors (new ones prefixed by >>):

   net/core/filter.c: In function 'bpf_get_socket_uid':
>> net/core/filter.c:2618:29: error: 'net' undeclared (first use in this 
>> function)
 kuid_t kuid = sock_net_uid(net, sk && sk_fullsock(sk) ?
^~~
   net/core/filter.c:2618:29: note: each undeclared identifier is reported only 
once for each function it appears in

vim +/net +2618 net/core/filter.c

  2612  .arg1_type  = ARG_PTR_TO_CTX,
  2613  };
  2614  
  2615  BPF_CALL_1(bpf_get_socket_uid, struct sk_buff *, skb)
  2616  {
  2617  struct sock *sk = skb->sk;
> 2618  kuid_t kuid = sock_net_uid(net, sk && sk_fullsock(sk) ?
  2619 sk : NULL);
  2620  return (u32)kuid.val;
  2621  }

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: application/gzip

[PATCH net-next v2 2/2] Add a eBPF helper function to retrieve socket uid

[Chenbo Feng]

From: Chenbo Feng 

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 
---
 include/uapi/linux/bpf.h |  9 -
 net/core/filter.c| 17 +
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6923d21..4854027 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -455,6 +455,12 @@ 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), \
@@ -503,7 +509,8 @@ 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 632fb91..523ed08 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2612,6 +2612,21 @@ 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 = skb->sk;
+   kuid_t kuid = sock_net_uid(net, sk && sk_fullsock(sk) ?
+  sk : NULL);
+   return (u32)kuid.val;
+}
+
+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)
 {
@@ -2637,6 +2652,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return bpf_get_trace_printk_proto();
case BPF_FUNC_get_socket_cookie:
return _get_socket_cookie_proto;
+   case BPF_FUNC_get_socket_uid:
+   return _get_socket_uid_proto;
default:
return NULL;
}
-- 
2.7.4