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Message-ID: <20211203053001.740945-1-houtao1@huawei.com>
Date: Fri, 3 Dec 2021 13:30:01 +0800
From: Hou Tao <houtao1@...wei.com>
To: Alexei Starovoitov <ast@...nel.org>
CC: Martin KaFai Lau <kafai@...com>, Yonghong Song <yhs@...com>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <houtao1@...wei.com>
Subject: [PATCH bpf-next v5] 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@...wei.com>
Acked-by: Yonghong Song <yhs@...com>
Acked-by: Martin KaFai Lau <kafai@...com>
---
v5:
* rebased on bpf-next
* patch #1 "bpf: Clean-up bpf_verifier_vlog() for BPF_LOG_KERNEL log level"
has been merged, so drop it
* doesn't pass max_total to bpf_verifier_log_attr_valid() because
now the max log buffer size of btf and verifier are the same.
v4: https://www.spinics.net/lists/bpf/msg50807.html
* rebased on bpf-next
* add Acked-by tags
v3: https://www.spinics.net/lists/bpf/msg48992.html
* rebased on bpf-next
* address comments from Daniel Borkmann:
patch #1: add prefix "BPF: " instead of "BPF:" for error message
patch #2: remove uncessary parenthesis, keep the max buffer length
setting of btf verifier, and add Fixes tag.
v2: https://www.spinics.net/lists/bpf/msg48809.html
* rebased on bpf-next
* patch #1: add a trailing newline if needed (suggested by Martin)
* add patch #2
v1: https://www.spinics.net/lists/bpf/msg48550.html
---
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 c8a78e830fca..182b16a91084 100644
--- 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 ed4258cb0832..d442dc07a8a1 100644
--- 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 6522ffdea487..1126b75fe650 100644
--- 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)) {
--
2.29.2
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