linux-kernel - Re: [PATCH v8 3/5] selftests/sgx: Dump enclave memory map

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Date:   Sat, 12 Jun 2021 07:27:23 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     shuah@...nel.org, linux-kselftest@...r.kernel.org,
        linux-sgx@...r.kernel.org,
        Reinette Chatre <reinette.chatre@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 3/5] selftests/sgx: Dump enclave memory map

On Fri, Jun 11, 2021 at 04:45:19PM -0600, Shuah Khan wrote:
> On 6/10/21 2:30 AM, Jarkko Sakkinen wrote:
> > Often, it's useful to check whether /proc/self/maps looks sane when
> > dealing with memory mapped objects, especially when they are JIT'ish
> > dynamically constructed objects. Therefore, dump "/dev/sgx_enclave"
> > matching lines from the memory map in FIXTURE_SETUP().
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
> > ---
> >   tools/testing/selftests/sgx/main.c | 14 ++++++++++++++
> >   1 file changed, 14 insertions(+)
> > 
> > diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
> > index 6da19b6bf287..14030f8b85ff 100644
> > --- a/tools/testing/selftests/sgx/main.c
> > +++ b/tools/testing/selftests/sgx/main.c
> > @@ -117,6 +117,8 @@ FIXTURE_SETUP(enclave)
> >   	Elf64_Sym *sgx_enter_enclave_sym = NULL;
> >   	struct vdso_symtab symtab;
> >   	struct encl_segment *seg;
> > +	char maps_line[256];
> > +	FILE *maps_file;
> >   	unsigned int i;
> >   	void *addr;
> > @@ -167,6 +169,18 @@ FIXTURE_SETUP(enclave)
> >   	memset(&self->run, 0, sizeof(self->run));
> >   	self->run.tcs = self->encl.encl_base;
> > +	maps_file = fopen("/proc/self/maps", "r");
> 
> I almost applied these. Does this require root access, if so,
> please add logic to skip the test if non-root user runs it.
> 
> Same comments for all other paths that might require root access.

As Dave stated, it does not. A process can inspect its own state
through /proc/self path. E.g. Chrome web browser uses /proc/self/exe
to initialize multiple instances of itself for browser tabs...

As far as other things go, this patch set does not bind to any other
new OS resources.

> thanks,
> -- Shuah

/Jarkko