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Subject[PATCH 5.10 137/563] bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)
Date
From: Hou Tao <houtao1@huawei.com>

[ Upstream commit 866de407444398bc8140ea70de1dba5f91cc34ac ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/bpf_verifier.h | 7 +++++++
kernel/bpf/btf.c | 3 +--
kernel/bpf/verifier.c | 6 +++---
3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 6e330ff2f28df..391bc1480dfb1 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -367,6 +367,13 @@ 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 72534a6f4b96e..dc497eaf22663 100644
--- a/kernel/bpf/btf.c
+++ b/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;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b43c9de34a2c2..c623c3e549210 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12349,11 +12349,11 @@ 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)) {
--
2.34.1


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