Commit 866de407 authored Dec 03, 2021 by Hou Tao Committed by Alexei Starovoitov Dec 04, 2021

bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)



BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.

Fixes: 8580ac94 ("bpf: Process in-kernel BTF")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.com

parent da54ab14

include/linux/bpf_verifier.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -396,6 +396,13 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
		log->level == BPF_LOG_KERNEL);
		}

		static inline bool
		bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log)
		{
		return log->len_total >= 128 && log->len_total <= UINT_MAX >> 2 &&
		log->level && log->ubuf && !(log->level & ~BPF_LOG_MASK);
		}

		#define BPF_MAX_SUBPROGS 256

		struct bpf_subprog_info {

kernel/bpf/btf.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -4473,8 +4473,7 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size,
		log->len_total = log_size;

		/* log attributes have to be sane */
		if (log->len_total < 128 \|\| log->len_total > UINT_MAX >> 2 \|\|
		!log->level \|\| !log->ubuf) {
		if (!bpf_verifier_log_attr_valid(log)) {
		err = -EINVAL;
		goto errout;
		}

kernel/bpf/verifier.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -14050,12 +14050,12 @@ int bpf_check(struct bpf_prog *prog, union bpf_attr attr, bpfptr_t uattr)
		log->ubuf = (char __user *) (unsigned long) attr->log_buf;
		log->len_total = attr->log_size;

		ret = -EINVAL;
		/* log attributes have to be sane */
		if (log->len_total < 128 \|\| log->len_total > UINT_MAX >> 2 \|\|
		!log->level \|\| !log->ubuf \|\| log->level & ~BPF_LOG_MASK)
		if (!bpf_verifier_log_attr_valid(log)) {
		ret = -EINVAL;
		goto err_unlock;
		}
		}

		if (IS_ERR(btf_vmlinux)) {
		/* Either gcc or pahole or kernel are broken. */