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bpf: Allow all printable characters in BTF DATASEC names

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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 <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-15-eddyz87@gmail.com
This commit is contained in:
Eduard Zingerman 2024-03-06 12:45:28 +02:00 • committed by Andrii Nakryiko
parent 733e5e8754
commit bd70a8fb7c
1 changed files with 15 additions and 1 deletions
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16
kernel/bpf/btf.c
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@ -809,9 +809,23 @@ static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
return __btf_name_valid(btf, 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) 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) static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)