From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0996C25B0C for ; Sat, 6 Aug 2022 08:52:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230247AbiHFIwg (ORCPT ); Sat, 6 Aug 2022 04:52:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229609AbiHFIwe (ORCPT ); Sat, 6 Aug 2022 04:52:34 -0400 Received: from mail-ed1-x534.google.com (mail-ed1-x534.google.com [IPv6:2a00:1450:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F3F411C0F; Sat, 6 Aug 2022 01:52:33 -0700 (PDT) Received: by mail-ed1-x534.google.com with SMTP id x21so5938092edd.3; Sat, 06 Aug 2022 01:52:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=8fIC7ahPt/yl/Wyy4QWb7dX1zPPvhwOFguvsp8IXkz8=; b=WiebgT5b2J4a0+leH+elpcb5xrOH20I+e99nRYnioqk0cPGLYuSR65D/V5ao0bRQN6 lpooaDZR1Gb26N2xT9OQjoK3+ONLmWGohPc3ssSa2n7ltPgoX1Avn2Z6xhvfe+7eCLN9 /V+TyRhiIFdTc+ZDrjcxfs0Mq91wD8GYPY2SougDba7OXMhWYIiHqYBYQhE+PPO8QoaF 3r9h3RVMvyPHPH+Do2dzzmwqjdsn+gX9FBDIrn1d90/oTwFV8p1TdnnDd1wZ4bOcn36m jXkopJvRk3vyLhTvvGIuM55ghDEZHv0QvX91GJyZ73YDfQ0VMJe+P6P169teRsYlCZ/o Yu2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=8fIC7ahPt/yl/Wyy4QWb7dX1zPPvhwOFguvsp8IXkz8=; b=JZTP3XuVcd3MrBu6nt8o1y7mM/X1WUaSFBWtfhBaW4CmlLGB11ztjFXpaXnbi5zEiP Avpfo+pmx6dlm3i74ye/Kq8k1NiMXKJMhklFXfXB0C36KnNplJtH7LmcJ4A6ua4Ygyok S5XWrxR/XnVwVV36SvNl90TwFf6jDqlPUuyOKatlBaeGBXNAvPqbiqHdPUejKLthfUIC KYA2Lzf7I1s94xarqJgos7MOyosoz2RqxQeyU1obQjm5efRV2C/XeN9tGMmUek/3NGGr ZKTxulHPHqCzb72tHqEhoQcoScbc+U7RrIj0H/hTWyHrwV2uD8qatTs6ra+Q2Wvkj1V5 bA5Q== X-Gm-Message-State: ACgBeo1g9YxOYgLyngRL+X0//wcZ9Txp52tJCYw+GSq+Djt07QBn8fY6 Lqzgt9LFIO/8UIpuM57+vi0= X-Google-Smtp-Source: AA6agR7I3BPzMaJLhn7mIBm8oYPE933dMZssupMAVRo2LmXHgjANUX3pIUiEIg0GbYRxMFeejYFBKQ== X-Received: by 2002:a05:6402:2691:b0:43d:ba10:854b with SMTP id w17-20020a056402269100b0043dba10854bmr9583625edd.158.1659775951887; Sat, 06 Aug 2022 01:52:31 -0700 (PDT) Received: from gmail.com (195-38-112-141.pool.digikabel.hu. [195.38.112.141]) by smtp.gmail.com with ESMTPSA id m17-20020a1709062ad100b0072b7d76211dsm2434804eje.107.2022.08.06.01.52.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 06 Aug 2022 01:52:31 -0700 (PDT) Sender: Ingo Molnar Date: Sat, 6 Aug 2022 10:52:29 +0200 From: Ingo Molnar To: Kyle Huey Cc: Dave Hansen , Thomas Gleixner , Borislav Petkov , Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Paolo Bonzini , Andy Lutomirski , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Robert O'Callahan , David Manouchehri Subject: Re: [PATCH v4 2/2] selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace Message-ID: References: <20220805230158.39378-1-khuey@kylehuey.com> <20220805230158.39378-2-khuey@kylehuey.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220805230158.39378-2-khuey@kylehuey.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Kyle Huey wrote: > From: Kyle Huey > > This tests PTRACE_SETREGSET with NT_X86_XSTATE modifying PKRU directly and > removing the PKRU bit from XSTATE_BV. > > Signed-off-by: Kyle Huey > --- > tools/testing/selftests/vm/pkey-x86.h | 12 +++ > tools/testing/selftests/vm/protection_keys.c | 88 +++++++++++++++++++- > 2 files changed, 98 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/vm/pkey-x86.h b/tools/testing/selftests/vm/pkey-x86.h > index b078ce9c6d2a..72c14cd3ddc7 100644 > --- a/tools/testing/selftests/vm/pkey-x86.h > +++ b/tools/testing/selftests/vm/pkey-x86.h > @@ -104,6 +104,18 @@ static inline int cpu_has_pkeys(void) > return 1; > } > > +static inline int cpu_max_xsave_size(void) > +{ > + unsigned long XSTATE_CPUID = 0xd; > + unsigned int eax; > + unsigned int ebx; > + unsigned int ecx; > + unsigned int edx; > + > + __cpuid_count(XSTATE_CPUID, 0, eax, ebx, ecx, edx); > + return ecx; > +} > + > static inline u32 pkey_bit_position(int pkey) > { > return pkey * PKEY_BITS_PER_PKEY; > diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c > index 291bc1e07842..27759d3ed9cd 100644 > --- a/tools/testing/selftests/vm/protection_keys.c > +++ b/tools/testing/selftests/vm/protection_keys.c > @@ -18,12 +18,13 @@ > * do a plain mprotect() to a mprotect_pkey() area and make sure the pkey sticks > * > * Compile like this: > - * gcc -o protection_keys -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm > - * gcc -m32 -o protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm > + * gcc -mxsave -o protection_keys -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm > + * gcc -mxsave -m32 -o protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm > */ > #define _GNU_SOURCE > #define __SANE_USERSPACE_TYPES__ > #include > +#include > #include > #include > #include > @@ -1550,6 +1551,86 @@ void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey) > do_not_expect_pkey_fault("plain read on recently PROT_EXEC area"); > } > > +#if defined(__i386__) || defined(__x86_64__) > +void test_ptrace_modifies_pkru(int *ptr, u16 pkey) > +{ > + pid_t child; > + int status, ret; > + int pkey_offset = pkey_reg_xstate_offset(); > + size_t xsave_size = cpu_max_xsave_size(); > + void *xsave; > + u32 *pkey_register; > + u64 *xstate_bv; > + struct iovec iov; > + > + child = fork(); > + pkey_assert(child >= 0); > + dprintf3("[%d] fork() ret: %d\n", getpid(), child); > + if (!child) { > + u32 pkey_register = read_pkey_reg(); > + > + ptrace(PTRACE_TRACEME, 0, 0, 0); > + raise(SIGSTOP); > + > + /* > + * need __read_pkey_reg() version so we do not do shadow_pkey_reg > + * checking > + */ > + if (pkey_register == __read_pkey_reg()) > + exit(1); > + > + raise(SIGSTOP); > + > + exit(__read_pkey_reg()); > + } > + > + pkey_assert(child == waitpid(child, &status, 0)); > + dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status); > + pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP); > + > + xsave = (void *)malloc(xsave_size); > + pkey_assert(xsave > 0); > + > + iov.iov_base = xsave; > + iov.iov_len = xsave_size; > + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); > + pkey_assert(ret == 0); > + > + pkey_register = (u32 *)(xsave + pkey_offset); > + pkey_assert(*pkey_register == read_pkey_reg()); > + > + *pkey_register = !read_pkey_reg(); > + > + ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov); > + pkey_assert(ret == 0); > + > + ret = ptrace(PTRACE_CONT, child, 0, 0); > + pkey_assert(ret == 0); > + > + pkey_assert(child == waitpid(child, &status, 0)); > + dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status); > + pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP); > + > + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); > + pkey_assert(ret == 0); > + > + xstate_bv = (u64 *)(xsave + 512); > + *xstate_bv &= ~(1 << 9); > + > + ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov); > + pkey_assert(ret == 0); > + > + ret = ptrace(PTRACE_CONT, child, 0, 0); > + pkey_assert(ret == 0); > + > + pkey_assert(child == waitpid(child, &status, 0)); > + dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status); > + pkey_assert(WIFEXITED(status)); > + pkey_assert(WEXITSTATUS(status) == 0); > + free(xsave); LGTM. May I ask for a bit more in terms of testing the ABI: writing some non-trivial (not all-zero and not all-ones) value into the PKRU register, forcing the child task to go through a FPU save/restore context switch and then reading it back and verifying the value, or something like that? Thanks, Ingo