From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 16 Sep 2014 17:25:31 +0100 Subject: [PATCH arm64-next v4] net: bpf: arm64: address randomize and write protect JIT code In-Reply-To: <1410853730-16470-1-git-send-email-dborkman@redhat.com> References: <1410853730-16470-1-git-send-email-dborkman@redhat.com> Message-ID: <20140916162531.GC32073@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Sep 16, 2014 at 08:48:50AM +0100, Daniel Borkmann wrote: > This is the ARM64 variant for 314beb9bcab ("x86: bpf_jit_comp: secure bpf > jit against spraying attacks"). > > Thanks to commit 11d91a770f1f ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX > support") which added necessary infrastructure, we can now implement > RO marking of eBPF generated JIT image pages and randomize start offset > for the JIT code, so that it does not reside directly on a page boundary > anymore. Likewise, the holes are filled with illegal instructions: here > we use BRK #0x100 (opcode 0xd4202000) to trigger a fault in the kernel > (unallocated BRKs would trigger a fault through do_debug_exception). This > seems more reliable as we don't have a guaranteed undefined instruction > space on ARM64. > > This is basically the ARM64 variant of what we already have in ARM via > commit 55309dd3d4cd ("net: bpf: arm: address randomize and write protect > JIT code"). Moreover, this commit also presents a merge resolution due to > conflicts with commit 60a3b2253c41 ("net: bpf: make eBPF interpreter images > read-only") as we don't use kfree() in bpf_jit_free() anymore to release > the locked bpf_prog structure, but instead bpf_prog_unlock_free() through > a different allocator. > > JIT tested on aarch64 with BPF test suite. > > Reference: http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html > Signed-off-by: Daniel Borkmann > Cc: Zi Shen Lim > Cc: Will Deacon > Cc: Catalin Marinas > Cc: David S. Miller > Cc: Alexei Starovoitov > --- > v3->v4: > - Inclusion into debug-monitors.h as suggested by Will > v2->v3: > - Use cpu_to_le32() as suggested by Zi/Will > v1->v2: > - Use brk insn as suggested by Catalin > Note: > - This patch depends on net-next being merged to mainline due > to the mentioned merge conflict. > > arch/arm64/include/asm/debug-monitors.h | 8 +++++++ > arch/arm64/net/bpf_jit_comp.c | 39 +++++++++++++++++++++++++-------- > 2 files changed, 38 insertions(+), 9 deletions(-) Thanks, Daniel, this looks great: Acked-by: Will Deacon We can merge this at -rc1. Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754641AbaIPQ0M (ORCPT ); Tue, 16 Sep 2014 12:26:12 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:33867 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754440AbaIPQ0K (ORCPT ); Tue, 16 Sep 2014 12:26:10 -0400 Date: Tue, 16 Sep 2014 17:25:31 +0100 From: Will Deacon To: Daniel Borkmann Cc: Catalin Marinas , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Zi Shen Lim , "David S. Miller" , Alexei Starovoitov Subject: Re: [PATCH arm64-next v4] net: bpf: arm64: address randomize and write protect JIT code Message-ID: <20140916162531.GC32073@arm.com> References: <1410853730-16470-1-git-send-email-dborkman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1410853730-16470-1-git-send-email-dborkman@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 16, 2014 at 08:48:50AM +0100, Daniel Borkmann wrote: > This is the ARM64 variant for 314beb9bcab ("x86: bpf_jit_comp: secure bpf > jit against spraying attacks"). > > Thanks to commit 11d91a770f1f ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX > support") which added necessary infrastructure, we can now implement > RO marking of eBPF generated JIT image pages and randomize start offset > for the JIT code, so that it does not reside directly on a page boundary > anymore. Likewise, the holes are filled with illegal instructions: here > we use BRK #0x100 (opcode 0xd4202000) to trigger a fault in the kernel > (unallocated BRKs would trigger a fault through do_debug_exception). This > seems more reliable as we don't have a guaranteed undefined instruction > space on ARM64. > > This is basically the ARM64 variant of what we already have in ARM via > commit 55309dd3d4cd ("net: bpf: arm: address randomize and write protect > JIT code"). Moreover, this commit also presents a merge resolution due to > conflicts with commit 60a3b2253c41 ("net: bpf: make eBPF interpreter images > read-only") as we don't use kfree() in bpf_jit_free() anymore to release > the locked bpf_prog structure, but instead bpf_prog_unlock_free() through > a different allocator. > > JIT tested on aarch64 with BPF test suite. > > Reference: http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html > Signed-off-by: Daniel Borkmann > Cc: Zi Shen Lim > Cc: Will Deacon > Cc: Catalin Marinas > Cc: David S. Miller > Cc: Alexei Starovoitov > --- > v3->v4: > - Inclusion into debug-monitors.h as suggested by Will > v2->v3: > - Use cpu_to_le32() as suggested by Zi/Will > v1->v2: > - Use brk insn as suggested by Catalin > Note: > - This patch depends on net-next being merged to mainline due > to the mentioned merge conflict. > > arch/arm64/include/asm/debug-monitors.h | 8 +++++++ > arch/arm64/net/bpf_jit_comp.c | 39 +++++++++++++++++++++++++-------- > 2 files changed, 38 insertions(+), 9 deletions(-) Thanks, Daniel, this looks great: Acked-by: Will Deacon We can merge this at -rc1. Will