linux-kernel - [PATCH bpf-next v6 4/5] selftests/bpf: Use vmlinux.h in socket_cookie

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Date:   Tue, 26 Jan 2021 19:35:58 +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, linux-kernel@...r.kernel.org,
        Florent Revest <revest@...omium.org>,
        KP Singh <kpsingh@...nel.org>
Subject: [PATCH bpf-next v6 4/5] selftests/bpf: Use vmlinux.h in socket_cookie_prog.c

When migrating from the bpf.h's to the vmlinux.h's definition of struct
bps_sock, an interesting LLVM behavior happened. LLVM started producing
two fetches of ctx->sk in the sockops program this means that the
verifier could not keep track of the NULL-check on ctx->sk. Therefore,
we need to extract ctx->sk in a variable before checking and
dereferencing it.

Acked-by: KP Singh <kpsingh@...nel.org>
Signed-off-by: Florent Revest <revest@...omium.org>
---
 .../testing/selftests/bpf/progs/socket_cookie_prog.c  | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
index 81e84be6f86d..fbd5eaf39720 100644
--- a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
+++ b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
@@ -1,12 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2018 Facebook
 
-#include <linux/bpf.h>
-#include <sys/socket.h>
+#include "vmlinux.h"
 
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_endian.h>
 
+#define AF_INET6 10
+
 struct socket_cookie {
 	__u64 cookie_key;
 	__u32 cookie_value;
@@ -41,7 +42,7 @@ int set_cookie(struct bpf_sock_addr *ctx)
 SEC("sockops")
 int update_cookie(struct bpf_sock_ops *ctx)
 {
-	struct bpf_sock *sk;
+	struct bpf_sock *sk = ctx->sk;
 	struct socket_cookie *p;
 
 	if (ctx->family != AF_INET6)
@@ -50,10 +51,10 @@ int update_cookie(struct bpf_sock_ops *ctx)
 	if (ctx->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
 		return 1;
 
-	if (!ctx->sk)
+	if (!sk)
 		return 1;
 
-	p = bpf_sk_storage_get(&socket_cookies, ctx->sk, 0, 0);
+	p = bpf_sk_storage_get(&socket_cookies, sk, 0, 0);
 	if (!p)
 		return 1;
 
-- 
2.30.0.280.ga3ce27912f-goog