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: 8580ac9404f6 ("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

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index c8a78e8..182b16a 100644 (file)
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -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 {

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 2a902a9..36a5cc0 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -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;
                }

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6522ffd..1126b75 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -14050,11 +14050,11 @@ 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)) {