Re: [PATCH 08/11] powerpc/kernel: Add SIG_SYS support for compat tasks

[Kees Cook]

On Thu, Jul 23, 2015 at 3:21 AM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> SIG_SYS was added in commit a0727e8ce513 "signal, x86: add SIGSYS info
> and make it synchronous."
>
> Because we use the asm-generic struct siginfo, we got support for
> SIG_SYS for free as part of that commit.
>
> However there was no compat handling added for powerpc. That means we've
> been advertising the existence of signfo._sifields._sigsys to compat
> tasks, but not actually filling in the fields correctly.
>
> Luckily it looks like no one has noticed, presumably because the only
> user of SIGSYS in the kernel is seccomp filter, which we don't support
> yet.
>
> So before we enable seccomp filter, add compat handling for SIGSYS.
>
> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

> ---
>  arch/powerpc/include/asm/compat.h | 7 +++++++
>  arch/powerpc/kernel/signal_32.c   | 5 +++++
>  2 files changed, 12 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/compat.h b/arch/powerpc/include/asm/compat.h
> index b142b8e0ed9e..4f2df589ec1d 100644
> --- a/arch/powerpc/include/asm/compat.h
> +++ b/arch/powerpc/include/asm/compat.h
> @@ -174,6 +174,13 @@ typedef struct compat_siginfo {
>                         int _band;      /* POLL_IN, POLL_OUT, POLL_MSG */
>                         int _fd;
>                 } _sigpoll;
> +
> +               /* SIGSYS */
> +               struct {
> +                       unsigned int _call_addr; /* calling insn */
> +                       int _syscall;            /* triggering system call number */
> +                       unsigned int _arch;      /* AUDIT_ARCH_* of syscall */
> +               } _sigsys;
>         } _sifields;
>  } compat_siginfo_t;
>
> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
> index d3a831ac0f92..77f97284124e 100644
> --- a/arch/powerpc/kernel/signal_32.c
> +++ b/arch/powerpc/kernel/signal_32.c
> @@ -949,6 +949,11 @@ int copy_siginfo_to_user32(struct compat_siginfo __user *d, const siginfo_t *s)
>                 err |= __put_user(s->si_overrun, &d->si_overrun);
>                 err |= __put_user(s->si_int, &d->si_int);
>                 break;
> +       case __SI_SYS >> 16:
> +               err |= __put_user(ptr_to_compat(s->si_call_addr), &d->si_call_addr);
> +               err |= __put_user(s->si_syscall, &d->si_syscall);
> +               err |= __put_user(s->si_arch, &d->si_arch);
> +               break;
>         case __SI_RT >> 16: /* This is not generated by the kernel as of now.  */
>         case __SI_MESGQ >> 16:
>                 err |= __put_user(s->si_int, &d->si_int);
> --
> 2.1.0
>



-- 
Kees Cook
Chrome OS Security
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