From bd70a8fb7ca4fcb078086f4d96b048aaf1aa4786 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Wed, 6 Mar 2024 12:45:28 +0200 Subject: [PATCH] bpf: Allow all printable characters in BTF DATASEC names The intent is to allow libbpf to use SEC("?.struct_ops") to identify struct_ops maps that are optional, e.g. like in the following BPF code: SEC("?.struct_ops") struct test_ops optional_map = { ... }; Which yields the following BTF: ... [13] DATASEC '?.struct_ops' size=0 vlen=... ... To load such BTF libbpf rewrites DATASEC name before load. After this patch the rewrite won't be necessary. Signed-off-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240306104529.6453-15-eddyz87@gmail.com --- kernel/bpf/btf.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 6ff0bd1a91d561..170d017e8e4afc 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -809,9 +809,23 @@ static bool btf_name_valid_identifier(const struct btf *btf, u32 offset) return __btf_name_valid(btf, offset); } +/* Allow any printable character in DATASEC names */ static bool btf_name_valid_section(const struct btf *btf, u32 offset) { - return __btf_name_valid(btf, offset); + /* offset must be valid */ + const char *src = btf_str_by_offset(btf, offset); + const char *src_limit; + + /* set a limit on identifier length */ + src_limit = src + KSYM_NAME_LEN; + src++; + while (*src && src < src_limit) { + if (!isprint(*src)) + return false; + src++; + } + + return !*src; } static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)