diff mbox series

[bpf-next,v6,4/5] selftests/bpf: Use vmlinux.h in socket_cookie_prog.c

Message ID 20210126183559.1302406-4-revest@chromium.org (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series [bpf-next,v6,1/5] bpf: Be less specific about socket cookies guarantees | expand

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Commit Message

Florent Revest Jan. 26, 2021, 6:35 p.m. UTC 
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 <revest@chromium.org>
---
 .../testing/selftests/bpf/progs/socket_cookie_prog.c  | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Comments

Andrii Nakryiko Jan. 27, 2021, 8:57 p.m. UTC | #1 
On Tue, Jan 26, 2021 at 10:36 AM Florent Revest <revest@chromium.org> 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 <revest@chromium.org>
> ---

Acked-by: Andrii Nakryiko <andrii@kernel.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
>
diff mbox series

Patch

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;