From 77d2e05abd45886dcad2b632c738cf46b9f7c19e Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Sat, 24 Mar 2018 11:44:23 -0700 Subject: [PATCH] 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 Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- include/linux/bpf_verifier.h | 7 +++++++ kernel/bpf/verifier.c | 19 +++++++++++-------- 2 files changed, 18 insertions(+), 8 deletions(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index c30668414b22..7e61c395fddf 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -166,6 +166,11 @@ static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log) return log->len_used >= log->len_total - 1; } +static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) +{ + return log->level && log->ubuf && !bpf_verifier_log_full(log); +} + #define BPF_MAX_SUBPROGS 256 /* single container for all structs @@ -192,6 +197,8 @@ struct bpf_verifier_env { u32 subprog_cnt; }; +void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, + va_list args); __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, const char *fmt, ...); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1e84e02ff733..8acd2207e412 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); } -- 2.11.0