From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann 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 Message-ID: <59D6A80F.8030208@iogearbox.net> References: <20171005153422.8947-1-jakub.kicinski@netronome.com> <20171005153422.8947-6-jakub.kicinski@netronome.com> <59D69FAB.1020605@iogearbox.net> <20171005142647.7a8d87a3@cakuba.netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, oss-drivers@netronome.com To: Jakub Kicinski Return-path: Received: from www62.your-server.de ([213.133.104.62]:56945 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751381AbdJEVpx (ORCPT ); Thu, 5 Oct 2017 17:45:53 -0400 In-Reply-To: <20171005142647.7a8d87a3@cakuba.netronome.com> Sender: netdev-owner@vger.kernel.org List-ID: 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!