[PATCH V2 3/3] ARM: net: bpf_jit: add support for jitted seccomp filters.

[Mircea Gherzan]

2013/3/18 Nicolas Schichan <nschichan at freebox.fr>:
> This patch selects HAVE_SECCOMP_FILTER_JIT in the ARM Kconfig file,
> implements and seccomp_jit_compile() and seccomp_jit_free(), and adds
> support for BPF_S_ANC_SECCOMP_LD_W instruction.
>
> BPF_S_ANC_SECCOMP_LD_W instructions trigger the generation of a call
> to C function seccomp_bpf_load().
>
> Signed-off-by: Nicolas Schichan <nschichan at freebox.fr>
> ---
>  arch/arm/Kconfig          |    1 +
>  arch/arm/net/bpf_jit_32.c |   36 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 37 insertions(+)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index dedf02b..b3dce17 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -24,6 +24,7 @@ config ARM
>         select HAVE_ARCH_SECCOMP_FILTER
>         select HAVE_ARCH_TRACEHOOK
>         select HAVE_BPF_JIT
> +       select HAVE_SECCOMP_FILTER_JIT
>         select HAVE_C_RECORDMCOUNT
>         select HAVE_DEBUG_KMEMLEAK
>         select HAVE_DMA_API_DEBUG
> diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
> index 0ea29e0..86e3b78 100644
> --- a/arch/arm/net/bpf_jit_32.c
> +++ b/arch/arm/net/bpf_jit_32.c
> @@ -548,6 +548,15 @@ load_common:
>                         emit_err_ret(ARM_COND_NE, ctx);
>                         emit(ARM_MOV_R(r_A, ARM_R0), ctx);
>                         break;
> +#ifdef CONFIG_SECCOMP_FILTER_JIT
> +               case BPF_S_ANC_SECCOMP_LD_W:
> +                       ctx->seen |= SEEN_CALL;
> +                       emit_mov_i(ARM_R3, (u32)seccomp_bpf_load, ctx);
> +                       emit_mov_i(ARM_R0, k, ctx);
> +                       emit_blx_r(ARM_R3, ctx);
> +                       emit(ARM_MOV_R(r_A, ARM_R0), ctx);
> +                       break;
> +#endif
>                 case BPF_S_LD_W_IND:
>                         load_order = 2;
>                         goto load_ind;
> @@ -956,3 +965,30 @@ void bpf_jit_free(struct sk_filter *fp)
>                 schedule_work(work);
>         }
>  }
> +
> +#ifdef CONFIG_SECCOMP_FILTER_JIT
> +void seccomp_jit_compile(struct seccomp_filter *fp)
> +{
> +       struct jit_ctx ctx;
> +
> +       memset(&ctx, 0, sizeof(ctx));
> +       ctx.prog_len = fp->len;
> +       ctx.prog_insns = fp->insns;
> +
> +       __bpf_jit_compile(&ctx);
> +       if (ctx.target)
> +               fp->bpf_func = (void*)ctx.target;
> +}
> +
> +void seccomp_jit_free(struct seccomp_filter *fp)
> +{
> +       struct work_struct *work;
> +
> +       if (fp->bpf_func != sk_run_filter) {
> +               work = (struct work_struct *)fp->bpf_func;
> +
> +               INIT_WORK(work, bpf_jit_free_worker);
> +               schedule_work(work);
> +       }
> +}
> +#endif
> --
> 1.7.10.4
>

Acked-by: Mircea Gherzan <mgherzan at gmail.com>