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bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)

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[ Upstream commit 866de40744 ]

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: 8580ac9404 ("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>
This commit is contained in:
Hou Tao 2021-12-03 13:30:01 +08:00 • committed by Justin Hammond
parent f3588f766b
commit c6234bcbc6
3 changed files with 11 additions and 5 deletions
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7
include/linux/bpf_verifier.h
View file

@ -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 {

3
kernel/bpf/btf.c
View file

@ -4332,8 +4332,7 @@ 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;
}

6
kernel/bpf/verifier.c
View file

@ -13759,11 +13759,11 @@ 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)) {