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From: Florent Revest <revest@chromium.org>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	kpsingh@chromium.org, revest@google.com, jackmanb@chromium.org,
	linux-kernel@vger.kernel.org,
	Florent Revest <revest@chromium.org>,
	KP Singh <kpsingh@kernel.org>
Subject: [PATCH bpf-next v7 4/5] selftests/bpf: Use vmlinux.h in socket_cookie_prog.c
Date: Wed, 10 Feb 2021 12:14:05 +0100
Message-ID: <20210210111406.785541-4-revest@chromium.org> (raw)
In-Reply-To: <20210210111406.785541-1-revest@chromium.org>

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@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.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;
 
-- 
2.30.0.478.g8a0d178c01-goog


  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-10 11:14 [PATCH bpf-next v7 1/5] bpf: Be less specific about socket cookies guarantees Florent Revest
2021-02-10 11:14 ` [PATCH bpf-next v7 2/5] bpf: Expose bpf_get_socket_cookie to tracing programs Florent Revest
2021-02-10 19:51   ` Andrii Nakryiko
2021-02-10 19:55     ` Florent Revest
2021-02-12  2:28   ` Alexei Starovoitov
2021-02-10 11:14 ` [PATCH bpf-next v7 3/5] selftests/bpf: Integrate the socket_cookie test to test_progs Florent Revest
2021-02-10 11:14 ` Florent Revest [this message]
2021-02-10 11:14 ` [PATCH bpf-next v7 5/5] selftests/bpf: Add a selftest for the tracing bpf_get_socket_cookie Florent Revest
2021-02-12  2:20 ` [PATCH bpf-next v7 1/5] bpf: Be less specific about socket cookies guarantees patchwork-bot+netdevbpf

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