From: Daniel Borkmann <daniel@iogearbox•net>
To: Jakub Kicinski <kubakici@wp•pl>
Cc: netdev@vger•kernel.org, alexei.starovoitov@gmail•com,
oss-drivers@netronome•com
Subject: Re: [PATCH net-next 5/5] bpf: write back the verifier log buffer as it gets filled
Date: Thu, 05 Oct 2017 23:45:51 +0200 [thread overview]
Message-ID: <59D6A80F.8030208@iogearbox.net> (raw)
In-Reply-To: <20171005142647.7a8d87a3@cakuba.netronome.com>
On 10/05/2017 11:26 PM, Jakub Kicinski wrote:
> On Thu, 05 Oct 2017 23:10:03 +0200, Daniel Borkmann wrote:
>>> include/linux/bpf_verifier.h | 7 +++--
>>> kernel/bpf/verifier.c | 64 +++++++++++++++++++++++++++++++-------------
>>> 2 files changed, 50 insertions(+), 21 deletions(-)
>>>
>>> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
>>> index 598802dd1897..c0f0e210c3f8 100644
>>> --- a/include/linux/bpf_verifier.h
>>> +++ b/include/linux/bpf_verifier.h
>>> @@ -140,10 +140,13 @@ struct bpf_verifier_env {
>>> bool seen_direct_write;
>>> struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
>>>
>>> - u32 log_level;
>>> + char __user *log_ubuf;
>>> + u32 log_usize;
>>> + u32 log_ulen;
>>> + char *log_buf;
>>> u32 log_size;
>>> u32 log_len;
>>> - char *log_buf;
>>> + u32 log_level;
>>
>> Small request: given we'd now have log_{level,ubuf,usize,ulen,buf,size,len}
>> in struct bpf_verifier_env, could we abstract that a bit e.g. into something
>> like struct bpf_verifier_log, which has level and kbuf and ubuf as members
>> of which {k,u}buf would be something like struct bpf_verifier_buf with three
>> members (mem or buf, len_total, len_used) or such. I think most of patch 1
>> is on passing env into verbose, so likely wouldn't be too much change required
>> for this, but would be nice to make that a bit more structured if we need to
>> touch it anyway.
>
> I thought about it but got put off by the fact that on of the bufs has
> a special __user marking.. So I don't think we can really have a common
> struct bpf_verifier_buf for the two :S Any suggestions on how to work
> around that?
Little bit annoying, I know. We have same 'issue' with struct sock_fprog_kern
and struct sock_fprog, probably something similar would be needed here for
the bpf_verifier_buf thing as well to make it two structs.
>>> ret = -ENOMEM;
>>> - env->log_buf = vmalloc(env->log_size);
>>> + env->log_buf = page_address(alloc_page(GFP_USER));
>>
>> alloc_page() can return NULL, if I spot this correctly, then page_address()
>> cannot handle NULL and would try to deref it, no? Am I missing something?
>
> Oh, I need to fix the nfp driver too, then!
prev parent reply other threads:[~2017-10-05 21:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-05 15:34 [PATCH net-next 0/5] bpf: get rid of global verifier state and reuse instruction printer Jakub Kicinski
2017-10-05 15:34 ` [PATCH net-next 1/5] bpf: remove global verifier log Jakub Kicinski
2017-10-05 15:34 ` [PATCH net-next 2/5] bpf: move instruction printing into a separate file Jakub Kicinski
2017-10-05 15:34 ` [PATCH net-next 3/5] tools: bpftool: use the kernel's instruction printer Jakub Kicinski
2017-10-05 15:34 ` [PATCH net-next 4/5] bpf: don't rely on the verifier lock for metadata_dst allocation Jakub Kicinski
2017-10-05 15:34 ` [PATCH net-next 5/5] bpf: write back the verifier log buffer as it gets filled Jakub Kicinski
2017-10-05 21:10 ` Daniel Borkmann
2017-10-05 21:26 ` Jakub Kicinski
2017-10-05 21:45 ` Daniel Borkmann [this message]
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