From patchwork Mon Aug 8 14:15:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kyle Huey X-Patchwork-Id: 12938840 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 2A303C25B0C for ; Mon, 8 Aug 2022 14:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231898AbiHHOQB (ORCPT ); Mon, 8 Aug 2022 10:16:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243181AbiHHOPn (ORCPT ); Mon, 8 Aug 2022 10:15:43 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9337CDA for ; Mon, 8 Aug 2022 07:15:42 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id q9-20020a17090a2dc900b001f58bcaca95so7907340pjm.3 for ; Mon, 08 Aug 2022 07:15:42 -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; bh=pG2ctVJXo4i6wIZyM4i+Ghh/SkIZeHnSqWmH/J73kw8=; b=i8sQzDFJxieaZCTqiKpLCFMcNqzUHDOyA/vmoIry52AIjdnuvgIIIOvvlCNhnNfatA L1UnXotKwRIMEQzg6nZV63Dn1djXASTnou8zHkDWnS01Ibt2jCOdOLjtqGVpWL7DIkNM ncU1jmQd8cVh7R9WNPQDd+U+8tdk8VGTrpqL3HEtWHWQJPaK5b6drxtryK50bglJzZyt 3lGqKOcUKvtuWm66RlMLRgnDs7eLeSbKOU9rOedrsIGeIUiysmF33pylYH3rmlQ2ILt4 ObvJHyQdSVOWOECriVn3XpPYy4tca/mfeWFYLnvV4zuV/qK7JtuHDvJmAc5ZAQjaIFEZ NQeA== 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; bh=pG2ctVJXo4i6wIZyM4i+Ghh/SkIZeHnSqWmH/J73kw8=; b=Yn/ZGETAgrPqf5TOtu7ziX3p6Lrk4mFoteKWgZ+sVESuiXu9c9ZMG+lWnGiTE1rSoO ZsHGrVSBGDFD2mcb32GNqRsJ7Q8QPaJy0dSCfKzjTG7dt3GJimwTuyhegO0mwRtic4JB S18f+4nVoIaOlc1HbAdZGeo7LvdgWeM/rOz8QIsAZO2D/bmpZmr3loc4DrQleN8eA/pq OhHVJLehNiTQLTZUWWVzj1/DgceS53/Xc00OkPSxBbYHy+IuaUg11NElVl68rGiStJEU PTZxZDQc03e0ji3C3Ko6a40E1NetCVeVaOt6PwOjJDheahWtiOBYp+54/oLek+bi5jgW 9Xvw== X-Gm-Message-State: ACgBeo3KWlL8cUpKgNQzYLuYTETAdu6spvFwcY5ONwxZSRrpulTtVrli DRHVDbh70p0LDugyk0WQ8LU3ug== X-Google-Smtp-Source: AA6agR6OFDGCCYGm5yHn9DjQ4qQFexr/TGf+qoDuw2FHA1wa/C5koEX7nKBtA8GC21ShSl8MJjDlNQ== X-Received: by 2002:a17:902:f688:b0:16f:28:ea27 with SMTP id l8-20020a170902f68800b0016f0028ea27mr18424504plg.151.1659968142316; Mon, 08 Aug 2022 07:15:42 -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 l7-20020a170902f68700b0016eede528b4sm8967357plg.61.2022.08.08.07.15.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Aug 2022 07:15:42 -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 , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Robert O'Callahan , David Manouchehri , Kyle Huey Subject: [PATCH v5 2/2] selftests/vm/pkeys: Add a regression test for setting PKRU through ptrace Date: Mon, 8 Aug 2022 07:15:38 -0700 Message-Id: <20220808141538.102394-2-khuey@kylehuey.com> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220808141538.102394-1-khuey@kylehuey.com> References: <20220808141538.102394-1-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)