Messages in this thread | | | Subject | Re: [PATCH v2] seccomp: not compatible with ARM OABI | From | Eric Paris <> | Date | Thu, 07 Nov 2013 13:56:37 -0500 |
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On Thu, 2013-11-07 at 10:39 -0800, Kees Cook wrote: > On Thu, Nov 7, 2013 at 10:16 AM, Andy Lutomirski <luto@amacapital.net> wrote: > > On Thu, Nov 7, 2013 at 9:47 AM, Kees Cook <keescook@chromium.org> wrote: > >> Make sure that seccomp filter won't be built when ARM OABI is in use, > >> since there is work needed to distinguish calling conventions. Until > >> that is done (which is likely never since OABI is deprecated), make > >> sure seccomp filter is unavailable in the OABI world. > >> > >> Signed-off-by: Kees Cook <keescook@chromium.org> > >> --- > >> v2: > >> - toggle availability via HAVE_ARCH_SECCOMP_FILTER; James Hogan. > >> --- > >> arch/arm/Kconfig | 7 ++++++- > >> 1 file changed, 6 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > >> index 0a1dc697333c..a0a8590f3609 100644 > >> --- a/arch/arm/Kconfig > >> +++ b/arch/arm/Kconfig > >> @@ -23,7 +23,7 @@ config ARM > >> select HARDIRQS_SW_RESEND > >> select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL > >> select HAVE_ARCH_KGDB > >> - select HAVE_ARCH_SECCOMP_FILTER > >> + select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT) > >> select HAVE_ARCH_TRACEHOOK > >> select HAVE_BPF_JIT > >> select HAVE_CONTEXT_TRACKING > >> @@ -1735,6 +1735,11 @@ config OABI_COMPAT > >> in memory differs between the legacy ABI and the new ARM EABI > >> (only for non "thumb" binaries). This option adds a tiny > >> overhead to all syscalls and produces a slightly larger kernel. > >> + > >> + The seccomp filter system will not be available when this is > >> + selected, since there is no way yet to sensibly distinguish > >> + between calling conventions during filtering. > >> + > >> If you know you'll be using only pure EABI user space then you > >> can say N here. If this option is not selected and you attempt > >> to execute a legacy ABI binary then the result will be > >> -- > >> 1.7.9.5 > >> > >> > > > > FWIW, OABI-only (i.e. !AEABI, as opposed to OABI_COMPAT) is, in > > principle, supportable -- userspace would just have to know that, if > > build for OABI, the calling convention is different. > > Right -- I opted for enforcing seccomp-on-ARM-means-EABI. > > > I doubt this is worth supporting, though, and, if no one complains > > about your patch for a couple releases, then that would mean we could > > get away with adding AUDIT_ARCH_ARM_OABI or something (maybe for > > seccomp only) if needed.
Audit already has: (ARM && AEABI && !OABI_COMPAT) adding AUDIT_ARCH_ARM_OABI means we could support it and no worries about ABI breakage.
Isn't x32 similarly screwy? Does it work because the syscall numbers are different?
-Eric
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