bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)

stable inclusion
from stable-v5.10.94
commit 924886fa2246d24d0f0f80096300f607f1b7a829
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=924886fa2246d24d0f0f80096300f607f1b7a829

--------------------------------

[ Upstream commit 866de407 ]

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: NHou Tao <houtao1@huawei.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NYonghong Song <yhs@fb.com>
Acked-by: NMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.comSigned-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

include/linux/bpf_verifier.h

@@ -369,6 +369,13 @@ 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

@@ -4135,8 +4135,7 @@ static struct btf *btf_parse(void __user *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

@@ -12390,12 +12390,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 		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. */