From: Daniel Borkmann <daniel@iogearbox•net>
To: Daniel Mack <daniel@zonque•org>, ast@fb•com
Cc: dh.herrmann@gmail•com, netdev@vger•kernel.org, davem@davemloft•net
Subject: Re: [PATCH v1 1/2] bpf: add a longest prefix match trie map implementation
Date: Fri, 06 Jan 2017 11:43:21 +0100 [thread overview]
Message-ID: <586F74C9.3020305@iogearbox.net> (raw)
In-Reply-To: <2edd2b2b-a89e-0df0-c1dc-fdaee2315597@zonque.org>
On 01/05/2017 09:14 PM, Daniel Mack wrote:
[...]
> In my use case, the actual value of a node is in fact ignored, all that
> matters is whether a node exists in a trie or not. The test code uses
> u64 for its tests.
>
> I can change it around so that the value size can be defined by
> userspace, but ideally it would also support 0-byte lengths then. The
> bpf map syscall handler should handle the latter just fine if I read the
> code correctly?
Right now no map is allowed to have value size of 0, but since kmalloc()
would return ZERO_SIZE_PTR in such case, it looks like it should
work^tm, although I haven't checked whether it's guaranteed that all
the copy_{from,to}_user() implementations work with 0 size as well
and whether ubsan would complain on the ZERO_SIZE_PTR for memcpy() etc.
Perhaps better to reject value size of 0 initially and later on follow
up with making the syscall code more robust for such cases (afaik, for
the htab this was also on todo.)?
Thanks,
Daniel
next prev parent reply other threads:[~2017-01-06 10:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-29 17:28 [PATCH v1 0/2] bpf: add longest prefix match map Daniel Mack
2016-12-29 17:28 ` [PATCH v1 1/2] bpf: add a longest prefix match trie map implementation Daniel Mack
2017-01-05 16:25 ` Daniel Borkmann
2017-01-05 16:40 ` Daniel Borkmann
2017-01-05 20:01 ` Daniel Borkmann
2017-01-05 20:14 ` Daniel Mack
2017-01-06 10:43 ` Daniel Borkmann [this message]
2017-01-06 19:59 ` Alexei Starovoitov
2017-01-05 20:04 ` Daniel Mack
2017-01-05 20:20 ` Daniel Borkmann
2016-12-29 17:28 ` [PATCH v1 2/2] bpf: Add tests for the lpm trie map Daniel Mack
2016-12-30 20:25 ` [PATCH v1 0/2] bpf: add longest prefix match map David Miller
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