[PATCH 1/5] bpf: Allow non struct type for btf ctx access

From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
	Andrii Nakryiko <andriin@fb.com>, Yonghong Song <yhs@fb.com>,
	Martin KaFai Lau <kafai@fb.com>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	David Miller <davem@redhat.com>
Subject: [PATCH 1/5] bpf: Allow non struct type for btf ctx access
Date: Sun, 29 Dec 2019 15:37:36 +0100	[thread overview]
Message-ID: <20191229143740.29143-2-jolsa@kernel.org> (raw)
In-Reply-To: <20191229143740.29143-1-jolsa@kernel.org>

I'm not sure why the restriction was added,
but I can't access pointers to POD types like
const char * when probing vfs_read function.

Removing the check and allow non struct type
access in context.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/btf.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index ed2075884724..ae90f60ac1b8 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3712,12 +3712,6 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 	/* skip modifiers */
 	while (btf_type_is_modifier(t))
 		t = btf_type_by_id(btf, t->type);
-	if (!btf_type_is_struct(t)) {
-		bpf_log(log,
-			"func '%s' arg%d type %s is not a struct\n",
-			tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]);
-		return false;
-	}
 	bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
 		tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)],
 		__btf_name_by_offset(btf, t->name_off));
-- 
2.21.1

