[PATCH net-next v4 01/11] net-timestamp: add support for bpf_setsockopt()

[Jason Xing <kerneljasonxing@gmail.com>]

From: Jason Xing <kernelxing@tencent.com>

Users can write the following code to enable the bpf extension:
bpf_setsockopt(skops, SOL_SOCKET, SK_BPF_CB_FLAGS, &flags, sizeof(flags));

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/net/sock.h             |  7 +++++++
 include/uapi/linux/bpf.h       |  8 ++++++++
 net/core/filter.c              | 22 ++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  1 +
 4 files changed, 38 insertions(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index 7464e9f9f47c..0dd464ba9e46 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -303,6 +303,7 @@ struct sk_filter;
   *	@sk_stamp: time stamp of last packet received
   *	@sk_stamp_seq: lock for accessing sk_stamp on 32 bit architectures only
   *	@sk_tsflags: SO_TIMESTAMPING flags
+  *	@sk_bpf_cb_flags: used for bpf_setsockopt
   *	@sk_use_task_frag: allow sk_page_frag() to use current->task_frag.
   *			   Sockets that can be used under memory reclaim should
   *			   set this to false.
@@ -445,6 +446,12 @@ struct sock {
 	u32			sk_reserved_mem;
 	int			sk_forward_alloc;
 	u32			sk_tsflags;
+#ifdef CONFIG_BPF_SYSCALL
+#define SK_BPF_CB_FLAG_TEST(SK, FLAG) ((SK)->sk_bpf_cb_flags & (FLAG))
+	u32			sk_bpf_cb_flags;
+#else
+#define SK_BPF_CB_FLAG_TEST(SK, FLAG) 0
+#endif
 	__cacheline_group_end(sock_write_rxtx);
 
 	__cacheline_group_begin(sock_write_tx);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4162afc6b5d0..e629e09b0b31 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6903,6 +6903,13 @@ enum {
 	BPF_SOCK_OPS_ALL_CB_FLAGS       = 0x7F,
 };
 
+/* Definitions for bpf_sk_cb_flags */
+enum {
+	SK_BPF_CB_TX_TIMESTAMPING	= 1<<0,
+	SK_BPF_CB_MASK			= (SK_BPF_CB_TX_TIMESTAMPING - 1) |
+					   SK_BPF_CB_TX_TIMESTAMPING
+};
+
 /* List of known BPF sock_ops operators.
  * New entries can only be added at the end
  */
@@ -7081,6 +7088,7 @@ enum {
 	TCP_BPF_SYN_IP		= 1006, /* Copy the IP[46] and TCP header */
 	TCP_BPF_SYN_MAC         = 1007, /* Copy the MAC, IP[46], and TCP header */
 	TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
+	SK_BPF_CB_FLAGS		= 1009, /* Used to set socket bpf flags */
 };
 
 enum {
diff --git a/net/core/filter.c b/net/core/filter.c
index 6625b3f563a4..f7e9f88e09b1 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5214,6 +5214,24 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = {
 	.arg1_type      = ARG_PTR_TO_CTX,
 };
 
+static int sk_bpf_set_cb_flags(struct sock *sk, sockptr_t optval, bool getopt)
+{
+	int sk_bpf_cb_flags;
+
+	if (getopt)
+		return -EINVAL;
+
+	if (copy_from_sockptr(&sk_bpf_cb_flags, optval, sizeof(sk_bpf_cb_flags)))
+		return -EFAULT;
+
+	if (sk_bpf_cb_flags & ~SK_BPF_CB_MASK)
+		return -EINVAL;
+
+	sk->sk_bpf_cb_flags = sk_bpf_cb_flags;
+
+	return 0;
+}
+
 static int sol_socket_sockopt(struct sock *sk, int optname,
 			      char *optval, int *optlen,
 			      bool getopt)
@@ -5230,6 +5248,7 @@ static int sol_socket_sockopt(struct sock *sk, int optname,
 	case SO_MAX_PACING_RATE:
 	case SO_BINDTOIFINDEX:
 	case SO_TXREHASH:
+	case SK_BPF_CB_FLAGS:
 		if (*optlen != sizeof(int))
 			return -EINVAL;
 		break;
@@ -5239,6 +5258,9 @@ static int sol_socket_sockopt(struct sock *sk, int optname,
 		return -EINVAL;
 	}
 
+	if (optname == SK_BPF_CB_FLAGS)
+		return sk_bpf_set_cb_flags(sk, KERNEL_SOCKPTR(optval), getopt);
+
 	if (getopt) {
 		if (optname == SO_BINDTODEVICE)
 			return -EINVAL;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 4162afc6b5d0..6b0a5b787b12 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7081,6 +7081,7 @@ enum {
 	TCP_BPF_SYN_IP		= 1006, /* Copy the IP[46] and TCP header */
 	TCP_BPF_SYN_MAC         = 1007, /* Copy the MAC, IP[46], and TCP header */
 	TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
+	SK_BPF_CB_FLAGS		= 1009, /* Used to set socket bpf flags */
 };
 
 enum {
-- 
2.37.3