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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Andrii Nakryiko <andriin@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>,
	"ast@kernel.org" <ast@kernel.org>,
	"daniel@iogearbox.net" <daniel@iogearbox.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>
Subject: Re: [bpf-next PATCH] bpf: libbpf, add kernel version section parsing back
Date: Fri, 18 Oct 2019 18:33:16 -0700	[thread overview]
Message-ID: <CAADnVQLyi9os2FK9OSiZ2CMKtEd7NOR=P_Q-Qd9_0Lu9dn63kw@mail.gmail.com> (raw)
In-Reply-To: <4da33f52-e857-9997-4226-4eae0f440df9@fb.com>

On Fri, Oct 18, 2019 at 9:52 AM Andrii Nakryiko <andriin@fb.com> wrote:
> On 10/18/19 7:41 AM, John Fastabend wrote:
> > With commit "libbpf: stop enforcing kern_version,..." we removed the
> > kernel version section parsing in favor of querying for the kernel
> > using uname() and populating the version using the result of the
> > query. After this any version sections were simply ignored.
> >
> > Unfortunately, the world of kernels is not so friendly. I've found some
> > customized kernels where uname() does not match the in kernel version.
> > To fix this so programs can load in this environment this patch adds
> > back parsing the section and if it exists uses the user specified
> > kernel version to override the uname() result. However, keep most the
> > kernel uname() discovery bits so users are not required to insert the
> > version except in these odd cases.
> >
> > Fixes: 5e61f27070292 ("libbpf: stop enforcing kern_version, populate it for users")
> > Signed-off-by: John Fastabend <john.fastabend@gmail.com>
> > ---
> In the name of not breaking users of weird kernels :)
> Acked-by: Andrii Nakryiko <andriin@fb.com>

What does it mean that uname is cheated?
Can libbpf read it from /proc/sys/kernel/osrelease ?
or /proc/version?
Is that read only or user space can somehow overwrite it?

  reply	other threads:[~2019-10-19  1:33 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-18 14:41 John Fastabend
2019-10-18 16:51 ` Andrii Nakryiko
2019-10-19  1:33   ` Alexei Starovoitov [this message]
2019-10-19  4:41     ` John Fastabend
2019-10-18 19:11 ` Daniel Borkmann

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