linux-kernel - [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket

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Date:   Thu,  3 Dec 2020 22:33:28 +0100
From:   Florent Revest <revest@...omium.org>
To:     bpf@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kpsingh@...omium.org, revest@...gle.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next v2 1/3] bpf: Expose bpf_get_socket_cookie to tracing programs

This creates a new helper proto because the existing
bpf_get_socket_cookie_sock_proto has a ARG_PTR_TO_CTX argument and only
works for BPF programs where the context is a sock.

This helper could also be useful to other BPF program types such as LSM.

Signed-off-by: Florent Revest <revest@...gle.com>
---
 include/uapi/linux/bpf.h       | 7 +++++++
 kernel/trace/bpf_trace.c       | 4 ++++
 net/core/filter.c              | 7 +++++++
 tools/include/uapi/linux/bpf.h | 7 +++++++
 4 files changed, 25 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c3458ec1f30a..3e0e33c43998 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1662,6 +1662,13 @@ union bpf_attr {
  * 	Return
  * 		A 8-byte long non-decreasing number.
  *
+ * u64 bpf_get_socket_cookie(void *sk)
+ * 	Description
+ * 		Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
+ * 		*sk*, but gets socket from a BTF **struct sock**.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
  * 	Return
  * 		The owner UID of the socket associated to *skb*. If the socket
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d255bc9b2bfa..14ad96579813 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1725,6 +1725,8 @@ raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 	}
 }
 
+extern const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto;
+
 const struct bpf_func_proto *
 tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -1748,6 +1750,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_sk_storage_get_tracing_proto;
 	case BPF_FUNC_sk_storage_delete:
 		return &bpf_sk_storage_delete_tracing_proto;
+	case BPF_FUNC_get_socket_cookie:
+		return &bpf_get_socket_cookie_sock_tracing_proto;
 #endif
 	case BPF_FUNC_seq_printf:
 		return prog->expected_attach_type == BPF_TRACE_ITER ?
diff --git a/net/core/filter.c b/net/core/filter.c
index 2ca5eecebacf..177c4e5e529d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4631,6 +4631,13 @@ static const struct bpf_func_proto bpf_get_socket_cookie_sock_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 };
 
+const struct bpf_func_proto bpf_get_socket_cookie_sock_tracing_proto = {
+	.func		= bpf_get_socket_cookie_sock,
+	.gpl_only	= false,
+	.ret_type	= RET_INTEGER,
+	.arg1_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
+};
+
 BPF_CALL_1(bpf_get_socket_cookie_sock_ops, struct bpf_sock_ops_kern *, ctx)
 {
 	return __sock_gen_cookie(ctx->sk);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c3458ec1f30a..3e0e33c43998 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1662,6 +1662,13 @@ union bpf_attr {
  * 	Return
  * 		A 8-byte long non-decreasing number.
  *
+ * u64 bpf_get_socket_cookie(void *sk)
+ * 	Description
+ * 		Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
+ * 		*sk*, but gets socket from a BTF **struct sock**.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
  * 	Return
  * 		The owner UID of the socket associated to *skb*. If the socket
-- 
2.29.2.576.ga3fc446d84-goog