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SubjectRe: [PATCH V2 3/3] ARM: net: bpf_jit: add support for jitted seccomp filters.
From
2013/3/18 Nicolas Schichan <nschichan@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@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@gmail.com>


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