From patchwork Mon Oct 3 20:42:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kyle Huey X-Patchwork-Id: 12997780 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 10A50C433FE for ; Mon, 3 Oct 2022 20:42:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229611AbiJCUmn (ORCPT ); Mon, 3 Oct 2022 16:42:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229522AbiJCUmg (ORCPT ); Mon, 3 Oct 2022 16:42:36 -0400 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 689884B491 for ; Mon, 3 Oct 2022 13:42:35 -0700 (PDT) Received: by mail-pg1-x529.google.com with SMTP id c7so10638681pgt.11 for ; Mon, 03 Oct 2022 13:42:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kylehuey.com; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date; bh=4qLQoJQNu1CZW/0PSN7Xr+tyBQTuegEan0yqmUNKFmY=; b=Nbg7Y+ulmuPhnyslETGZ9FvylenNR9uhx3/BBNxvuUUMxMIKLTRrScH/NOzmr/1SSA Y8vQKwIgZygsltUnLEqEzazMnXiIQBDiVYiInXA1IaJ26uYHcNh/GdrHCDyt4faw3oLR CbK4W8v7AzMPsvL18a+sh8GvK6yWrYLov0xVvbBNEEo/5x2+SgtPUILYa3RgqAzuPM3k SOLSwPBo+lbONMU6LlDwBLwtX27TZ+fkRN2S0Pm8vGB4TkXCeVIupX7d47a4a03mBGhn hasU2wxPwgaSeKV7Kc5dOm82UFxhQMSr5MhcDLOWotBHAI80r2RqNdhW+eG6X8PybxRY kUVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date; bh=4qLQoJQNu1CZW/0PSN7Xr+tyBQTuegEan0yqmUNKFmY=; b=u5ThBs3X/6VzJEVOoy2dOoUsrOjZaVvvFSt0Ly/JrlChiIftgyHZ5k/RSBo2CY38JB u2QJYb0rm3ZuQnegU9pDX/8zBQrhH/wAZb/UFiPxC5+5087I82u88+FWHs6PuzXAaVcE BUVkQiRvVCgDSgbFcLlz4Bxaz0fP6+IsW3HXTOqJJbDs494zxgOHM2crqS4crSKaRB6V va/7j8bqbU6TIReQH9GtreqRzy45JT8rj3/efVBExbxsgxOIlkoyp7YVwbcP6gdARoh/ 9D42M4Vkg7PtFGiUrKK2E2z/Ws9FBYNi4VJTBhfUOMiggVO9D/+BmKor1q6ayaLhX0Ga f8CQ== X-Gm-Message-State: ACrzQf3LNv68XQTPBdy5EiwhpljKgDhiNbdnBu/0Pe03VqeoFL66cXEY Iv18a8nxvuPMeNm93Sllpo939A== X-Google-Smtp-Source: AMsMyM4thTNJXA6D7jB785C8pcwUMO3FeXB26ake8K/B8O5iQPd8J2W8NefAVsVBdak8eQ3DeRQ3fg== X-Received: by 2002:a65:6cc8:0:b0:3fe:2b89:cc00 with SMTP id g8-20020a656cc8000000b003fe2b89cc00mr20444357pgw.599.1664829754854; Mon, 03 Oct 2022 13:42:34 -0700 (PDT) Received: from minbar.home.kylehuey.com (c-71-198-251-229.hsd1.ca.comcast.net. [71.198.251.229]) by smtp.gmail.com with ESMTPSA id c3-20020a170903234300b0017834a6966csm7693795plh.176.2022.10.03.13.42.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 13:42:34 -0700 (PDT) From: Kyle Huey X-Google-Original-From: Kyle Huey To: Dave Hansen , Thomas Gleixner , Borislav Petkov Cc: Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Paolo Bonzini , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Robert O'Callahan , David Manouchehri , Kyle Huey , Borislav Petkov , stable@vger.kernel.org Subject: [PATCH v6 1/2] x86/fpu: Allow PKRU to be (once again) written by ptrace. Date: Mon, 3 Oct 2022 13:42:30 -0700 Message-Id: <20221003204231.104972-1-khuey@kylehuey.com> X-Mailer: git-send-email 2.37.3 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org From: Kyle Huey When management of the PKRU register was moved away from XSTATE, emulation of PKRU's existence in XSTATE was added for reading PKRU through ptrace, but not for writing PKRU through ptrace. This can be seen by running gdb and executing `p $pkru`, `set $pkru = 42`, and `p $pkru`. On affected kernels (5.14+) the write to the PKRU register (which gdb performs through ptrace) is ignored. There are three APIs that write PKRU: sigreturn, PTRACE_SETREGSET with NT_X86_XSTATE, and KVM_SET_XSAVE. sigreturn still uses XRSTOR to write to PKRU. KVM_SET_XSAVE has its own special handling to make PKRU writes take effect (in fpu_copy_uabi_to_guest_fpstate). Push that down into copy_uabi_to_xstate and have PTRACE_SETREGSET with NT_X86_XSTATE pass in a pointer to the appropriate PKRU slot. copy_sigframe_from_user_to_xstate depends on copy_uabi_to_xstate populating the PKRU field in the task's XSTATE so that __fpu_restore_sig can do a XRSTOR from it, so continue doing that. This also adds code to initialize the PKRU value to the hardware init value (namely 0) if the PKRU bit is not set in the XSTATE header provided to ptrace, to match XRSTOR. Fixes: e84ba47e313d ("x86/fpu: Hook up PKRU into ptrace()") Signed-off-by: Kyle Huey Cc: Dave Hansen Cc: Thomas Gleixner Cc: Borislav Petkov Cc: stable@vger.kernel.org # 5.14+ --- arch/x86/kernel/fpu/core.c | 20 +++++++++----------- arch/x86/kernel/fpu/regset.c | 2 +- arch/x86/kernel/fpu/signal.c | 2 +- arch/x86/kernel/fpu/xstate.c | 25 ++++++++++++++++++++----- arch/x86/kernel/fpu/xstate.h | 4 ++-- 5 files changed, 33 insertions(+), 20 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 3b28c5b25e12..c273669e8a00 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -391,8 +391,6 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, { struct fpstate *kstate = gfpu->fpstate; const union fpregs_state *ustate = buf; - struct pkru_state *xpkru; - int ret; if (!cpu_feature_enabled(X86_FEATURE_XSAVE)) { if (ustate->xsave.header.xfeatures & ~XFEATURE_MASK_FPSSE) @@ -406,16 +404,16 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, if (ustate->xsave.header.xfeatures & ~xcr0) return -EINVAL; - ret = copy_uabi_from_kernel_to_xstate(kstate, ustate); - if (ret) - return ret; + /* + * Nullify @vpkru to preserve its current value if PKRU's bit isn't set + * in the header. KVM's odd ABI is to leave PKRU untouched in this + * case (all other components are eventually re-initialized). + * (Not clear that this is actually necessary for compat). + */ + if (!(ustate->xsave.header.xfeatures & XFEATURE_MASK_PKRU)) + vpkru = NULL; - /* Retrieve PKRU if not in init state */ - if (kstate->regs.xsave.header.xfeatures & XFEATURE_MASK_PKRU) { - xpkru = get_xsave_addr(&kstate->regs.xsave, XFEATURE_PKRU); - *vpkru = xpkru->pkru; - } - return 0; + return copy_uabi_from_kernel_to_xstate(kstate, ustate, vpkru); } EXPORT_SYMBOL_GPL(fpu_copy_uabi_to_guest_fpstate); #endif /* CONFIG_KVM */ diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c index 75ffaef8c299..6d056b68f4ed 100644 --- a/arch/x86/kernel/fpu/regset.c +++ b/arch/x86/kernel/fpu/regset.c @@ -167,7 +167,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, } fpu_force_restore(fpu); - ret = copy_uabi_from_kernel_to_xstate(fpu->fpstate, kbuf ?: tmpbuf); + ret = copy_uabi_from_kernel_to_xstate(fpu->fpstate, kbuf ?: tmpbuf, &target->thread.pkru); out: vfree(tmpbuf); diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 91d4b6de58ab..558076dbde5b 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -396,7 +396,7 @@ static bool __fpu_restore_sig(void __user *buf, void __user *buf_fx, fpregs = &fpu->fpstate->regs; if (use_xsave() && !fx_only) { - if (copy_sigframe_from_user_to_xstate(fpu->fpstate, buf_fx)) + if (copy_sigframe_from_user_to_xstate(tsk, buf_fx)) return false; } else { if (__copy_from_user(&fpregs->fxsave, buf_fx, diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index c8340156bfd2..8f14981a3936 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1197,7 +1197,7 @@ static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size, static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf, - const void __user *ubuf) + const void __user *ubuf, u32 *pkru) { struct xregs_state *xsave = &fpstate->regs.xsave; unsigned int offset, size; @@ -1246,6 +1246,21 @@ static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf, } } + /* + * Update the user protection key storage. Allow KVM to + * pass in a NULL pkru pointer if the mask bit is unset + * for its legacy ABI behavior. + */ + if (pkru) + *pkru = 0; + + if (hdr.xfeatures & XFEATURE_MASK_PKRU) { + struct pkru_state *xpkru; + + xpkru = __raw_xsave_addr(xsave, XFEATURE_PKRU); + *pkru = xpkru->pkru; + } + /* * The state that came in from userspace was user-state only. * Mask all the user states out of 'xfeatures': @@ -1264,9 +1279,9 @@ static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf, * Convert from a ptrace standard-format kernel buffer to kernel XSAVE[S] * format and copy to the target thread. Used by ptrace and KVM. */ -int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf) +int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru) { - return copy_uabi_to_xstate(fpstate, kbuf, NULL); + return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru); } /* @@ -1274,10 +1289,10 @@ int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf) * XSAVE[S] format and copy to the target thread. This is called from the * sigreturn() and rt_sigreturn() system calls. */ -int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate, +int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf) { - return copy_uabi_to_xstate(fpstate, NULL, ubuf); + return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru); } static bool validate_independent_components(u64 mask) diff --git a/arch/x86/kernel/fpu/xstate.h b/arch/x86/kernel/fpu/xstate.h index 5ad47031383b..a4ecb04d8d64 100644 --- a/arch/x86/kernel/fpu/xstate.h +++ b/arch/x86/kernel/fpu/xstate.h @@ -46,8 +46,8 @@ extern void __copy_xstate_to_uabi_buf(struct membuf to, struct fpstate *fpstate, u32 pkru_val, enum xstate_copy_mode copy_mode); extern void copy_xstate_to_uabi_buf(struct membuf to, struct task_struct *tsk, enum xstate_copy_mode mode); -extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf); -extern int copy_sigframe_from_user_to_xstate(struct fpstate *fpstate, const void __user *ubuf); +extern int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru); +extern int copy_sigframe_from_user_to_xstate(struct task_struct *tsk, const void __user *ubuf); extern void fpu__init_cpu_xstate(void); From patchwork Mon Oct 3 20:42:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kyle Huey X-Patchwork-Id: 12997781 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 AE238C433FE for ; Mon, 3 Oct 2022 20:42:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230050AbiJCUmp (ORCPT ); Mon, 3 Oct 2022 16:42:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230035AbiJCUmi (ORCPT ); Mon, 3 Oct 2022 16:42:38 -0400 Received: from mail-pg1-x529.google.com (mail-pg1-x529.google.com [IPv6:2607:f8b0:4864:20::529]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BE0A4BA50 for ; Mon, 3 Oct 2022 13:42:37 -0700 (PDT) Received: by mail-pg1-x529.google.com with SMTP id c7so10638742pgt.11 for ; Mon, 03 Oct 2022 13:42:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kylehuey.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=XCNEHMJr0hfjsQ+vnHehtUNGIlWFLDcrEGyzhvj9K5g=; b=CXJ8dGA/ffmTvSFWrVejIJaKtGXY++gZTlvcBhvkxiZdfbOoQwmMvfqvcYN6BuBjBL kwJHrjt52wKdbnYieGIG6evu9EwLcAsD1LkalSm8xrXYTmpt7kXRUeVop2AVaz7YgPkt oE3pop2M+0mLdQ0CgzIKSAm7tBu1dTk3uU6yfVdAdiGusUCq3ONGqQNgI0B+JxIUcZ5b U/2nJ2WFPbZVSEir7XwNYT1d6OEBwC9cOQTkCzBsKz+47ouvzvZoC66JTexklzCwG0gi Jl6btI2XflaTe4Vc6HwSsosIlMW+u/EXpcW5rZ/6C+SYzLIwztH2DYHJLYjiR5eLiwnr nNtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=XCNEHMJr0hfjsQ+vnHehtUNGIlWFLDcrEGyzhvj9K5g=; b=5pAuBAVy0pdktGyYZq9NBCYs9sADDuY1DVimU0Xg5izStd6UInfFbTzSupUHFVgBaO 1cHu6xaDAX71vq46uUKbgWMKt20jBjTaoGzAj16+v7iwSt+PGnUpcO1n1VpzMv4rh5mg Nj8zZsqKY2lenf9+KcXC4vqojw2FbA4FxqKvtxvx3QpxZ5svMSG6mzitSFbidY1Icu3o B+qdi5IVeT5uwAQP5lGrd01+CL6sxI8oFtl07Dr2/0fS4FQ4RmbdDA+E/Xia95eHlyH3 wbUJU7Ql7R8ObYk4u4suSH8ggJMhLLrGJcmGlL2DSSFCadJ0roW7AwTK00SfxyNqGYJr IbkA== X-Gm-Message-State: ACrzQf3jdGfqANcqKHTqSIAXqva8HH6ux1izkT9u8vK0s2qq4H1RReFH ujKZ12EoqXJvqQ4vRbwJVCUVGA== X-Google-Smtp-Source: AMsMyM5S3W4glbXlT91W9TaDgku4QWpy+oDiV9AxANcEO0043OsQNPIDgKBTNtxRIVxnD8/iQWX+ag== X-Received: by 2002:a05:6a00:2402:b0:52c:81cf:8df8 with SMTP id z2-20020a056a00240200b0052c81cf8df8mr24553293pfh.60.1664829756819; Mon, 03 Oct 2022 13:42:36 -0700 (PDT) Received: from minbar.home.kylehuey.com (c-71-198-251-229.hsd1.ca.comcast.net. [71.198.251.229]) by smtp.gmail.com with ESMTPSA id c3-20020a170903234300b0017834a6966csm7693795plh.176.2022.10.03.13.42.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 13:42:36 -0700 (PDT) From: Kyle Huey X-Google-Original-From: Kyle Huey To: Dave Hansen , Thomas Gleixner , Borislav Petkov Cc: Ingo Molnar , x86@kernel.org, "H. Peter Anvin" , Paolo Bonzini , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Robert O'Callahan , David Manouchehri , Kyle Huey Subject: [PATCH v6 2/2] selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace Date: Mon, 3 Oct 2022 13:42:31 -0700 Message-Id: <20221003204231.104972-2-khuey@kylehuey.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221003204231.104972-1-khuey@kylehuey.com> References: <20221003204231.104972-1-khuey@kylehuey.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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 | 131 ++++++++++++++++++- 2 files changed, 141 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..95f403a0c46d 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 +1551,129 @@ 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) +{ + u32 new_pkru; + 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; + + new_pkru = ~read_pkey_reg(); + /* Don't make PROT_EXEC mappings inaccessible */ + new_pkru &= ~3; + + child = fork(); + pkey_assert(child >= 0); + dprintf3("[%d] fork() ret: %d\n", getpid(), child); + if (!child) { + ptrace(PTRACE_TRACEME, 0, 0, 0); + /* Stop and allow the tracer to modify PKRU directly */ + raise(SIGSTOP); + + /* + * need __read_pkey_reg() version so we do not do shadow_pkey_reg + * checking + */ + if (__read_pkey_reg() != new_pkru) + exit(1); + + /* Stop and allow the tracer to clear XSTATE_BV for PKRU */ + raise(SIGSTOP); + + if (__read_pkey_reg() != 0) + exit(1); + + /* Stop and allow the tracer to examine PKRU */ + raise(SIGSTOP); + + exit(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); + + xsave = (void *)malloc(xsave_size); + pkey_assert(xsave > 0); + + /* Modify the PKRU register directly */ + 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 = new_pkru; + + ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + + /* Test that the modification is visible in ptrace before any execution */ + memset(xsave, 0xCC, xsave_size); + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + pkey_assert(*pkey_register == new_pkru); + + /* Execute the tracee */ + ret = ptrace(PTRACE_CONT, child, 0, 0); + pkey_assert(ret == 0); + + /* Test that the tracee saw the PKRU value change */ + pkey_assert(child == waitpid(child, &status, 0)); + dprintf3("[%d] waitpid(%d) status: %x\n", getpid(), child, status); + pkey_assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP); + + /* Test that the modification is visible in ptrace after execution */ + memset(xsave, 0xCC, xsave_size); + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + pkey_assert(*pkey_register == new_pkru); + + /* Clear the PKRU bit from XSTATE_BV */ + xstate_bv = (u64 *)(xsave + 512); + *xstate_bv &= ~(1 << 9); + + ret = ptrace(PTRACE_SETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + + /* Test that the modification is visible in ptrace before any execution */ + memset(xsave, 0xCC, xsave_size); + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + pkey_assert(*pkey_register == 0); + + ret = ptrace(PTRACE_CONT, child, 0, 0); + pkey_assert(ret == 0); + + /* Test that the tracee saw the PKRU value go to 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); + + /* Test that the modification is visible in ptrace after execution */ + memset(xsave, 0xCC, xsave_size); + ret = ptrace(PTRACE_GETREGSET, child, (void *)NT_X86_XSTATE, &iov); + pkey_assert(ret == 0); + pkey_assert(*pkey_register == 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); +} +#endif + void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey) { int size = PAGE_SIZE; @@ -1585,6 +1709,9 @@ void (*pkey_tests[])(int *ptr, u16 pkey) = { test_pkey_syscalls_bad_args, test_pkey_alloc_exhaust, test_pkey_alloc_free_attach_pkey0, +#if defined(__i386__) || defined(__x86_64__) + test_ptrace_modifies_pkru, +#endif }; void run_tests_once(void)