From: Ingo Molnar <mingo@kernel.org>
To: Robert O'Callahan <robert@ocallahan.org>
Cc: Andy Lutomirski <luto@kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
Jonathan Adams <jwadams@google.com>,
Kees Cook <keescook@chromium.org>, Paul Turner <pjt@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linux-MM <linux-mm@kvack.org>,
LSM List <linux-security-module@vger.kernel.org>,
X86 ML <x86@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 2/7] x86/sci: add core implementation for system call isolation
Date: Thu, 2 May 2019 17:20:16 +0200 [thread overview]
Message-ID: <20190502152016.GA51567@gmail.com> (raw)
In-Reply-To: <CAOp6jLa1Rs2xrhJ2wpWoFbJGHyB99OX9doQZc+dNqOSUMgURsw@mail.gmail.com>
* Robert O'Callahan <robert@ocallahan.org> wrote:
> On Sat, Apr 27, 2019 at 10:46 PM Ingo Molnar <mingo@kernel.org> wrote:
> > - A C language runtime that is a subset of current C syntax and
> > semantics used in the kernel, and which doesn't allow access outside
> > of existing objects and thus creates a strictly enforced separation
> > between memory used for data, and memory used for code and control
> > flow.
> >
> > - This would involve, at minimum:
> >
> > - tracking every type and object and its inherent length and valid
> > access patterns, and never losing track of its type.
> >
> > - being a lot more organized about initialization, i.e. no
> > uninitialized variables/fields.
> >
> > - being a lot more strict about type conversions and pointers in
> > general.
> >
> > - ... and a metric ton of other details.
>
> Several research groups have tried to do this, and it is very
> difficult to do. In particular this was almost exactly the goal of
> C-Cured [1]. Much more recently, there's Microsoft's CheckedC [2] [3],
> which is less ambitious. Check the references of the latter for lots
> of relevant work. If anyone really pursues this they should talk
> directly to researchers who've worked on this, e.g. George Necula; you
> need to know what *didn't* work well, which is hard to glean from
> papers. (Academic publishing is broken that way.)
>
> One problem with adopting "safe C" or Rust in the kernel is that most
> of your security mitigations (e.g. KASLR, CFI, other randomizations)
> probably need to remain in place as long as there is a significant
> amount of C in the kernel, which means the benefits from eliminating
> them will be realized very far in the future, if ever, which makes the
> whole exercise harder to justify.
>
> Having said that, I think there's a good case to be made for writing
> kernel code in Rust, e.g. sketchy drivers. The classes of bugs
> prevented in Rust are significantly broader than your usual safe-C
> dialect (e.g. data races).
>
> [1] https://web.eecs.umich.edu/~weimerw/p/p477-necula.pdf
> [2] https://www.microsoft.com/en-us/research/uploads/prod/2019/05/checkedc-post2019.pdf
> [3] https://github.com/Microsoft/checkedc
So what might work better is if we defined a Rust dialect that used C
syntax. I.e. the end result would be something like the 'c2rust' or
'citrus' projects, where code like this would be directly translatable to
Rust:
void gz_compress(FILE * in, gzFile out)
{
char buf[BUFLEN];
int len;
int err;
for (;;) {
len = fread(buf, 1, sizeof(buf), in);
if (ferror(in)) {
perror("fread");
exit(1);
}
if (len == 0)
break;
if (gzwrite(out, buf, (unsigned)len) != len)
error(gzerror(out, &err));
}
fclose(in);
if (gzclose(out) != Z_OK)
error("failed gzclose");
}
#[no_mangle]
pub unsafe extern "C" fn gz_compress(mut in_: *mut FILE, mut out: gzFile) {
let mut buf: [i8; 16384];
let mut len;
let mut err;
loop {
len = fread(buf, 1, std::mem::size_of_val(&buf), in_);
if ferror(in_) != 0 { perror("fread"); exit(1); }
if len == 0 { break ; }
if gzwrite(out, buf, len as c_uint) != len {
error(gzerror(out, &mut err));
};
}
fclose(in_);
if gzclose(out) != Z_OK { error("failed gzclose"); };
}
Example taken from:
https://gitlab.com/citrus-rs/citrus
Does this make sense?
Thanks,
Ingo
next prev parent reply other threads:[~2019-05-02 15:20 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-25 21:45 [RFC PATCH 0/7] x86: introduce system calls addess space isolation Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 1/7] x86/cpufeatures: add X86_FEATURE_SCI Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 2/7] x86/sci: add core implementation for system call isolation Mike Rapoport
2019-04-26 7:49 ` Peter Zijlstra
2019-04-28 5:45 ` Mike Rapoport
2019-04-26 8:31 ` Ingo Molnar
2019-04-26 9:58 ` Ingo Molnar
2019-04-26 21:26 ` Andy Lutomirski
2019-04-27 8:47 ` Ingo Molnar
2019-04-27 10:46 ` Ingo Molnar
2019-04-29 18:26 ` James Morris
2019-04-29 18:43 ` Andy Lutomirski
2019-04-29 18:46 ` Andy Lutomirski
2019-04-30 5:03 ` Ingo Molnar
2019-04-30 9:38 ` Peter Zijlstra
2019-04-30 11:05 ` Ingo Molnar
2019-05-02 11:35 ` Robert O'Callahan
2019-05-02 15:20 ` Ingo Molnar [this message]
2019-05-02 21:07 ` Robert O'Callahan
2019-04-26 14:44 ` James Bottomley
2019-04-26 14:46 ` Dave Hansen
2019-04-26 14:57 ` James Bottomley
2019-04-26 15:07 ` Andy Lutomirski
2019-04-26 15:19 ` James Bottomley
2019-04-26 17:40 ` Andy Lutomirski
2019-04-26 18:49 ` James Bottomley
2019-04-26 19:22 ` Andy Lutomirski
2019-04-25 21:45 ` [RFC PATCH 3/7] x86/entry/64: add infrastructure for switching to isolated syscall context Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 4/7] x86/sci: hook up isolated system call entry and exit Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification Mike Rapoport
2019-04-26 7:42 ` Peter Zijlstra
2019-04-28 5:47 ` Mike Rapoport
2019-04-30 16:44 ` Andy Lutomirski
2019-05-01 5:39 ` Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 6/7] security: enable system call isolation in kernel config Mike Rapoport
2019-04-25 21:45 ` [RFC PATCH 7/7] sci: add example system calls to exercse SCI Mike Rapoport
2019-04-26 0:30 ` [RFC PATCH 0/7] x86: introduce system calls addess space isolation Andy Lutomirski
2019-04-26 8:07 ` Jiri Kosina
2019-04-28 6:01 ` Mike Rapoport
2019-04-26 14:41 ` Dave Hansen
2019-04-28 6:08 ` Mike Rapoport
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