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Date: Fri, 4 Nov 2022 23:32:05 -0400 From: Paul Moore <paul@...l-moore.com> To: John Johansen <john.johansen@...onical.com> Cc: linux-security-module@...r.kernel.org, selinux@...r.kernel.org, netdev@...r.kernel.org, Alexei Starovoitov <alexei.starovoitov@...il.com> Subject: Re: [PATCH] lsm: make security_socket_getpeersec_stream() sockptr_t safe On Mon, Oct 31, 2022 at 5:59 AM John Johansen <john.johansen@...onical.com> wrote: > On 10/10/22 14:58, Paul Moore wrote: > > Commit 4ff09db1b79b ("bpf: net: Change sk_getsockopt() to take the > > sockptr_t argument") made it possible to call sk_getsockopt() > > with both user and kernel address space buffers through the use of > > the sockptr_t type. Unfortunately at the time of conversion the > > security_socket_getpeersec_stream() LSM hook was written to only > > accept userspace buffers, and in a desire to avoid having to change > > the LSM hook the commit author simply passed the sockptr_t's > > userspace buffer pointer. Since the only sk_getsockopt() callers > > at the time of conversion which used kernel sockptr_t buffers did > > not allow SO_PEERSEC, and hence the > > security_socket_getpeersec_stream() hook, this was acceptable but > > also very fragile as future changes presented the possibility of > > silently passing kernel space pointers to the LSM hook. > > > > There are several ways to protect against this, including careful > > code review of future commits, but since relying on code review to > > catch bugs is a recipe for disaster and the upstream eBPF maintainer > > is "strongly against defensive programming", this patch updates the > > LSM hook, and all of the implementations to support sockptr_t and > > safely handle both user and kernel space buffers. > > > > Signed-off-by: Paul Moore <paul@...l-moore.com> > > looks good to me Thanks. I just merged this into lsm/next. > Acked-by: John Johansen <john.johansen@...onical.com> -- paul-moore.com
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