Re: [PATCH v3 seccomp 5/5] seccomp/cache: Report cache data through /proc/pid/seccomp_cache

Jann Horn via Containers
2020-09-30T23:08:37Z

[adding x86 folks to enhance bikeshedding]

On Thu, Oct 1, 2020 at 12:59 AM Kees Cook <keescook@chromium.org> wrote:
> On Wed, Sep 30, 2020 at 10:19:16AM -0500, YiFei Zhu wrote:
> > From: YiFei Zhu <yifeifz2@illinois.edu>
> >
> > Currently the kernel does not provide an infrastructure to translate
> > architecture numbers to a human-readable name. Translating syscall
> > numbers to syscall names is possible through FTRACE_SYSCALL
> > infrastructure but it does not provide support for compat syscalls.
> >
> > This will create a file for each PID as /proc/pid/seccomp_cache.
> > The file will be empty when no seccomp filters are loaded, or be
> > in the format of:
> > <arch name> <decimal syscall number> <ALLOW | FILTER>
> > where ALLOW means the cache is guaranteed to allow the syscall,
> > and filter means the cache will pass the syscall to the BPF filter.
> >
> > For the docker default profile on x86_64 it looks like:
> > x86_64 0 ALLOW
> > x86_64 1 ALLOW
> > x86_64 2 ALLOW
> > x86_64 3 ALLOW
> > [...]
> > x86_64 132 ALLOW
> > x86_64 133 ALLOW
> > x86_64 134 FILTER
> > x86_64 135 FILTER
> > x86_64 136 FILTER
> > x86_64 137 ALLOW
> > x86_64 138 ALLOW
> > x86_64 139 FILTER
> > x86_64 140 ALLOW
> > x86_64 141 ALLOW
[...]
> > diff --git a/arch/x86/include/asm/seccomp.h b/arch/x86/include/asm/seccomp.h
> > index 7b3a58271656..33ccc074be7a 100644
> > --- a/arch/x86/include/asm/seccomp.h
> > +++ b/arch/x86/include/asm/seccomp.h
> > @@ -19,13 +19,16 @@
> > #ifdef CONFIG_X86_64
> > # define SECCOMP_ARCH_DEFAULT AUDIT_ARCH_X86_64
> > # define SECCOMP_ARCH_DEFAULT_NR NR_syscalls
> > +# define SECCOMP_ARCH_DEFAULT_NAME "x86_64"
> > # ifdef CONFIG_COMPAT
> > # define SECCOMP_ARCH_COMPAT AUDIT_ARCH_I386
> > # define SECCOMP_ARCH_COMPAT_NR IA32_NR_syscalls
> > +# define SECCOMP_ARCH_COMPAT_NAME "x86_32"
>
> I think this should be "ia32"? Is there a good definitive guide on this
> naming convention?

"man 2 syscall" calls them "x86-64" and "i386". The syscall table
files use ABI names "i386" and "64". The syscall stub prefixes use
"x64" and "ia32".

I don't think we have a good consistent naming strategy here. :P