Re: [PATCH bpf-next v6 4/5] selftests/bpf: Use vmlinux.h in socket_cookie_prog.c
From: Andrii Nakryiko <hidden>
Date: 2021-01-27 20:59:36
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On Tue, Jan 26, 2021 at 10:36 AM Florent Revest [off-list ref] wrote:
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> Signed-off-by: Florent Revest <redacted> ---
Acked-by: Andrii Nakryiko <andrii@kernel.org>
quoted hunk ↗ jump to hunk
.../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