bpf: Add bpf_verifier_vlog() and bpf_verifier_log_needed()
The BTF (BPF Type Format) verifier needs to reuse the current
BPF verifier log. Hence, it requires the following changes:
(1) Expose log_write() in verifier.c for other users.
Its name is renamed to bpf_verifier_vlog().
(2) The BTF verifier also needs to check
'log->level && log->ubuf && !bpf_verifier_log_full(log);'
independently outside of the current log_write(). It is
because the BTF verifier will do one-check before
making multiple calls to btf_verifier_vlog to log
the details of a type.
Hence, this check is also re-factored to a new function
bpf_verifier_log_needed(). Since it is re-factored,
we can check it before va_start() in the current
bpf_verifier_log_write() and verbose().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1e84e02..8acd220 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -168,15 +168,11 @@ struct bpf_call_arg_meta {
static DEFINE_MUTEX(bpf_verifier_lock);
-static void log_write(struct bpf_verifier_env *env, const char *fmt,
- va_list args)
+void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
+ va_list args)
{
- struct bpf_verifier_log *log = &env->log;
unsigned int n;
- if (!log->level || !log->ubuf || bpf_verifier_log_full(log))
- return;
-
n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
@@ -200,18 +196,25 @@ __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
{
va_list args;
+ if (!bpf_verifier_log_needed(&env->log))
+ return;
+
va_start(args, fmt);
- log_write(env, fmt, args);
+ bpf_verifier_vlog(&env->log, fmt, args);
va_end(args);
}
EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
+ struct bpf_verifier_env *env = private_data;
va_list args;
+ if (!bpf_verifier_log_needed(&env->log))
+ return;
+
va_start(args, fmt);
- log_write(private_data, fmt, args);
+ bpf_verifier_vlog(&env->log, fmt, args);
va_end(args);
}
