[PATCH 4.19 133/243] bpf: btf: implement btf_name_valid_identifier()

Greg Kroah-Hartman
2019-12-11T15:52:09Z

From: Yonghong Song <yhs@fb.com>

[ Upstream commit cdbb096adddb3f42584cecb5ec2e07c26815b71f ]

Function btf_name_valid_identifier() have been implemented in
bpf-next commit 2667a2626f4d ("bpf: btf: Add BTF_KIND_FUNC and
BTF_KIND_FUNC_PROTO"). Backport this function so later patch
can use it.

Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/btf.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index cfa27b7d1168c..f0f9109f59bac 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -5,6 +5,7 @@
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
+#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
@@ -426,6 +427,30 @@ static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
offset < btf->hdr.str_len;
}

+/* Only C-style identifier is permitted. This can be relaxed if
+ * necessary.
+ */
+static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
+{
+ /* offset must be valid */
+ const char *src = &btf->strings[offset];
+ const char *src_limit;
+
+ if (!isalpha(*src) && *src != '_')
+ return false;
+
+ /* set a limit on identifier length */
+ src_limit = src + KSYM_NAME_LEN;
+ src++;
+ while (*src && src < src_limit) {
+ if (!isalnum(*src) && *src != '_')
+ return false;
+ src++;
+ }
+
+ return !*src;
+}
+
static const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
if (!offset)
--
2.20.1