From: Florent Revest <revest@chromium.org>
To: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Cc: martin.lau@linux.dev, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, song@kernel.org, yhs@fb.com,
john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com,
haoluo@google.com, jolsa@kernel.org, nathan@kernel.org,
ndesaulniers@google.com, trix@redhat.com,
Florent Revest <revest@chromium.org>,
stable@vger.kernel.org
Subject: [PATCH bpf] bpf/btf: Accept function names that contain dots
Date: Thu, 15 Jun 2023 16:56:07 +0200 [thread overview]
Message-ID: <20230615145607.3469985-1-revest@chromium.org> (raw)
When building a kernel with LLVM=1, LLVM_IAS=0 and CONFIG_KASAN=y, LLVM
leaves DWARF tags for the "asan.module_ctor" & co symbols. In turn,
pahole creates BTF_KIND_FUNC entries for these and this makes the BTF
metadata validation fail because they contain a dot.
In a dramatic turn of event, this BTF verification failure can cause
the netfilter_bpf initialization to fail, causing netfilter_core to
free the netfilter_helper hashmap and netfilter_ftp to trigger a
use-after-free. The risk of u-a-f in netfilter will be addressed
separately but the existence of "asan.module_ctor" debug info under some
build conditions sounds like a good enough reason to accept functions
that contain dots in BTF.
Cc: stable@vger.kernel.org
Fixes: 1dc92851849c ("bpf: kernel side support for BTF Var and DataSec")
Signed-off-by: Florent Revest <revest@chromium.org>
---
kernel/bpf/btf.c | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6b682b8e4b50..72b32b7cd9cd 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -744,13 +744,12 @@ static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
return offset < btf->hdr.str_len;
}
-static bool __btf_name_char_ok(char c, bool first, bool dot_ok)
+static bool __btf_name_char_ok(char c, bool first)
{
if ((first ? !isalpha(c) :
!isalnum(c)) &&
c != '_' &&
- ((c == '.' && !dot_ok) ||
- c != '.'))
+ c != '.')
return false;
return true;
}
@@ -767,20 +766,20 @@ static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
return NULL;
}
-static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
+static bool __btf_name_valid(const struct btf *btf, u32 offset)
{
/* offset must be valid */
const char *src = btf_str_by_offset(btf, offset);
const char *src_limit;
- if (!__btf_name_char_ok(*src, true, dot_ok))
+ if (!__btf_name_char_ok(*src, true))
return false;
/* set a limit on identifier length */
src_limit = src + KSYM_NAME_LEN;
src++;
while (*src && src < src_limit) {
- if (!__btf_name_char_ok(*src, false, dot_ok))
+ if (!__btf_name_char_ok(*src, false))
return false;
src++;
}
@@ -788,17 +787,14 @@ static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
return !*src;
}
-/* Only C-style identifier is permitted. This can be relaxed if
- * necessary.
- */
static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
- return __btf_name_valid(btf, offset, false);
+ return __btf_name_valid(btf, offset);
}
static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
- return __btf_name_valid(btf, offset, true);
+ return __btf_name_valid(btf, offset);
}
static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
@@ -4422,7 +4418,7 @@ static s32 btf_var_check_meta(struct btf_verifier_env *env,
}
if (!t->name_off ||
- !__btf_name_valid(env->btf, t->name_off, true)) {
+ !__btf_name_valid(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
--
2.41.0.162.gfafddb0af9-goog
next reply other threads:[~2023-06-15 14:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-15 14:56 Florent Revest [this message]
2023-06-15 15:44 ` [PATCH bpf] bpf/btf: Accept function names that contain dots Florent Revest
2023-06-15 17:05 ` Eduard Zingerman
2023-06-19 11:20 ` Florent Revest
2023-06-19 13:55 ` Florent Revest
2023-06-19 15:24 ` Eduard Zingerman
2023-06-16 16:57 ` Andrii Nakryiko
2023-06-19 14:03 ` Florent Revest
2023-06-19 18:17 ` Yonghong Song
2023-06-20 13:24 ` Florent Revest
2023-06-20 14:38 ` Nick Desaulniers
2023-06-20 14:53 ` Yonghong Song
2023-06-20 15:07 ` Nick Desaulniers
2023-06-21 3:28 ` Yonghong Song
2023-06-21 8:43 ` Daniel Borkmann
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