From patchwork Thu Dec 14 10:17:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Roger_Pau_Monn=C3=A9?= X-Patchwork-Id: 13492705 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 708A4C41535 for ; Thu, 14 Dec 2023 10:18:00 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.654402.1021295 (Exim 4.92) (envelope-from ) id 1rDimo-0006VY-Dv; Thu, 14 Dec 2023 10:17:46 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 654402.1021295; Thu, 14 Dec 2023 10:17:46 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rDimo-0006U9-9I; Thu, 14 Dec 2023 10:17:46 +0000 Received: by outflank-mailman (input) for mailman id 654402; Thu, 14 Dec 2023 10:17:44 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rDimm-0006Da-NN for xen-devel@lists.xenproject.org; Thu, 14 Dec 2023 10:17:44 +0000 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [2a00:1450:4864:20::335]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 04d37c37-9a6a-11ee-98e9-6d05b1d4d9a1; Thu, 14 Dec 2023 11:17:43 +0100 (CET) Received: by mail-wm1-x335.google.com with SMTP id 5b1f17b1804b1-40c38de1ee4so56228455e9.0 for ; Thu, 14 Dec 2023 02:17:43 -0800 (PST) Received: from localhost ([213.195.127.70]) by smtp.gmail.com with ESMTPSA id fm21-20020a05600c0c1500b0040c03c3289bsm24222464wmb.37.2023.12.14.02.17.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Dec 2023 02:17:42 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 04d37c37-9a6a-11ee-98e9-6d05b1d4d9a1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1702549063; x=1703153863; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ViZ6HshgXIzZU2jJO110IUa3m0YwRdNIuCZWwBHHHR4=; b=RcGKljl3F+z6hAzSM7NwNsCjsTOLG8B1tfVtPpQVwIc7yqSWZcJzzbFvaPSMQUPqlj v1FkD2yVXBOeSGcCVsI9qGRQV9RbkSAb3KbJsOoRibabTLzkTz32QDPGZMRmmwVQek+b NHzLuZVN20ym/titjTUIkfR8nyatsANX/oqR0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702549063; x=1703153863; 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:message-id:reply-to; bh=ViZ6HshgXIzZU2jJO110IUa3m0YwRdNIuCZWwBHHHR4=; b=eP0YOPzmBeuxP4djDnLltivGkiBp4e3DoDFvlSc1qjjLqFdQp7FnrKyngjJXPdUHJi WmxbGiVVbdhfQVJp2tdLjpeQHmGs4PrBdxIWOyhjA6o0gv+/O3l+EzLMFkrH8Utv5Eev DsYxXq83GTZXSlmqAGxf8WDNSPFTfdBNoGAwc9BfK4GS0YxwHutypEwQ8FozfNkSJg50 Fa6OnjqdnqvZ0TQhRiCihV4SX6l65pybr6VZnQlAP/7DeOMBc4jdAZnsP8eGzWgaqWqq iYIz2RvKr9nIGYG9NVATflKmTjIH286MbklhdQaYLoRkV/4/LrkA11O/zn8CLOgtrzeC KIww== X-Gm-Message-State: AOJu0Yxbd7JKL3PI4lgLRum7FAB+iy9mjvBKIHnGfBOIj/gl6qRIjN+6 EfwTjT9BftmkbVa4s04C5+5ruIzXEiXq0qerbUM= X-Google-Smtp-Source: AGHT+IFrof9xmOuW95ijQWLTufyd6KrOVDaHydrGvFqct3533PxijnOPr2RuZI5T/3fRx6J6Lv8FuQ== X-Received: by 2002:a7b:cd89:0:b0:40b:5e59:e9e8 with SMTP id y9-20020a7bcd89000000b0040b5e59e9e8mr4510564wmj.135.1702549062650; Thu, 14 Dec 2023 02:17:42 -0800 (PST) From: Roger Pau Monne To: xen-devel@lists.xenproject.org Cc: Roger Pau Monne , Wei Liu , Anthony PERARD , Juergen Gross , Andrew Cooper , George Dunlap , Jan Beulich , Julien Grall , Stefano Stabellini Subject: [PATCH v3 2/4] xen/x86: introduce self modifying code test Date: Thu, 14 Dec 2023 11:17:17 +0100 Message-ID: <20231214101719.18770-3-roger.pau@citrix.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231214101719.18770-1-roger.pau@citrix.com> References: <20231214101719.18770-1-roger.pau@citrix.com> MIME-Version: 1.0 Introduce a helper to perform checks related to self modifying code, and start by creating a simple test to check that alternatives have been applied. Such test is hooked into the boot process and called just after alternatives have been applied. In case of failure a message is printed, and the hypervisor is tainted as not having passed the tests, this does require introducing a new taint bit (printed as 'A'). A new sysctl is also introduced to run the tests on demand. While there are no current users introduced here, further changes will introduce those, and it's helpful to have the interface defined in the sysctl header from the start. Note the sysctl visibility is not limited to x86, albeit the only implementation is for x86. It's expected that other architectures can reuse the same sysctl and structure, with possibly different tests. Leave adjusting those to when support for a different architecture is introduced, as the sysctl interface is not stable anyway. Signed-off-by: Roger Pau Monné --- Changes since v2: - Rename to smoc and place in test/smoc* - fix inline assembly. Changes since v1: - Rework test and interface. --- tools/include/xenctrl.h | 2 + tools/libs/ctrl/xc_misc.c | 14 ++++++ xen/arch/x86/Makefile | 1 + xen/arch/x86/include/asm/test-smoc.h | 18 ++++++++ xen/arch/x86/setup.c | 3 ++ xen/arch/x86/sysctl.c | 9 ++++ xen/arch/x86/test/Makefile | 1 + xen/arch/x86/test/smoc.c | 68 ++++++++++++++++++++++++++++ xen/common/kernel.c | 5 +- xen/include/public/sysctl.h | 10 ++++ xen/include/xen/lib.h | 1 + 11 files changed, 130 insertions(+), 2 deletions(-) create mode 100644 xen/arch/x86/include/asm/test-smoc.h create mode 100644 xen/arch/x86/test/Makefile create mode 100644 xen/arch/x86/test/smoc.c diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h index 2ef8b4e05422..0af796ae84e8 100644 --- a/tools/include/xenctrl.h +++ b/tools/include/xenctrl.h @@ -2658,6 +2658,8 @@ int xc_dt_overlay(xc_interface *xch, void *overlay_fdt, uint32_t overlay_fdt_size, uint8_t overlay_op); #endif +int xc_test_smoc(xc_interface *xch, uint32_t tests, uint32_t *result); + /* Compat shims */ #include "xenctrl_compat.h" diff --git a/tools/libs/ctrl/xc_misc.c b/tools/libs/ctrl/xc_misc.c index 5ecdfa2c7934..1d3d5929cf96 100644 --- a/tools/libs/ctrl/xc_misc.c +++ b/tools/libs/ctrl/xc_misc.c @@ -1021,6 +1021,20 @@ int xc_livepatch_replace(xc_interface *xch, char *name, uint32_t timeout, uint32 return _xc_livepatch_action(xch, name, LIVEPATCH_ACTION_REPLACE, timeout, flags); } +int xc_test_smoc(xc_interface *xch, uint32_t tests, uint32_t *result) +{ + struct xen_sysctl sysctl = { + .cmd = XEN_SYSCTL_test_smoc, + .u.test_smoc.tests = tests, + }; + int rc = do_sysctl(xch, &sysctl); + + if ( !rc ) + *result = sysctl.u.test_smoc.results; + + return rc; +} + /* * Local variables: * mode: C diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index f3abdf9cd111..ad5112b03c64 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_HVM) += hvm/ obj-y += mm/ obj-$(CONFIG_XENOPROF) += oprofile/ obj-$(CONFIG_PV) += pv/ +obj-y += test/ obj-y += x86_64/ obj-y += x86_emulate/ diff --git a/xen/arch/x86/include/asm/test-smoc.h b/xen/arch/x86/include/asm/test-smoc.h new file mode 100644 index 000000000000..2547b925d291 --- /dev/null +++ b/xen/arch/x86/include/asm/test-smoc.h @@ -0,0 +1,18 @@ +#ifndef _ASM_X86_TEST_SMC_H_ +#define _ASM_X86_TEST_SMC_H_ + +#include + +int test_smoc(uint32_t selection, uint32_t *results); + +#endif /* _ASM_X86_TEST_SMC_H_ */ + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index 3cba2be0af6c..e026b0ea5adc 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -58,6 +58,7 @@ #include #include #include +#include /* opt_nosmp: If true, secondary processors are ignored. */ static bool __initdata opt_nosmp; @@ -1951,6 +1952,8 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) alternative_branches(); + test_smoc(XEN_SYSCTL_TEST_SMOC_ALL, NULL); + /* * NB: when running as a PV shim VCPUOP_up/down is wired to the shim * physical cpu_add/remove functions, so launch the guest with only diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c index 1d40d82c5ad2..918e56631b94 100644 --- a/xen/arch/x86/sysctl.c +++ b/xen/arch/x86/sysctl.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -423,6 +424,14 @@ long arch_do_sysctl( break; } + case XEN_SYSCTL_test_smoc: + ret = test_smoc(sysctl->u.test_smoc.tests, + &sysctl->u.test_smoc.results); + if ( !ret && __copy_field_to_guest(u_sysctl, sysctl, + u.test_smoc.results) ) + ret = -EFAULT; + break; + default: ret = -ENOSYS; break; diff --git a/xen/arch/x86/test/Makefile b/xen/arch/x86/test/Makefile new file mode 100644 index 000000000000..b504b8196659 --- /dev/null +++ b/xen/arch/x86/test/Makefile @@ -0,0 +1 @@ +obj-y += smoc.o diff --git a/xen/arch/x86/test/smoc.c b/xen/arch/x86/test/smoc.c new file mode 100644 index 000000000000..e7529f937a5a --- /dev/null +++ b/xen/arch/x86/test/smoc.c @@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include + +#include +#include +#include + +static bool cf_check test_insn_replacement(void) +{ +#define EXPECTED_VALUE 2 + unsigned int r = ~EXPECTED_VALUE; + + alternative_io("", "mov %1, %0", X86_FEATURE_ALWAYS, + "+r" (r), "i" (EXPECTED_VALUE)); + + return r == EXPECTED_VALUE; +#undef EXPECTED_VALUE +} + +int test_smoc(uint32_t selection, uint32_t *results) +{ + struct { + unsigned int mask; + bool (*test)(void); + const char *name; + } static const tests[] = { + { XEN_SYSCTL_TEST_SMOC_INSN_REPL, &test_insn_replacement, + "alternative instruction replacement" }, + }; + unsigned int i; + + if ( selection & ~XEN_SYSCTL_TEST_SMOC_ALL ) + return -EINVAL; + + if ( results ) + *results = 0; + + printk(XENLOG_INFO "Checking Self Modify Code\n"); + + for ( i = 0; i < ARRAY_SIZE(tests); i++ ) + { + if ( !(selection & tests[i].mask) ) + continue; + + if ( tests[i].test() ) + { + if ( results ) + *results |= tests[i].mask; + continue; + } + + add_taint(TAINT_ERROR_SMOC); + printk(XENLOG_ERR "%s test failed\n", tests[i].name); + } + + return 0; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/common/kernel.c b/xen/common/kernel.c index 08dbaa2a054c..8ddfd309f65e 100644 --- a/xen/common/kernel.c +++ b/xen/common/kernel.c @@ -386,13 +386,14 @@ char *print_tainted(char *str) { if ( tainted ) { - snprintf(str, TAINT_STRING_MAX_LEN, "Tainted: %c%c%c%c%c%c", + snprintf(str, TAINT_STRING_MAX_LEN, "Tainted: %c%c%c%c%c%c%c", tainted & TAINT_MACHINE_INSECURE ? 'I' : ' ', tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', tainted & TAINT_SYNC_CONSOLE ? 'C' : ' ', tainted & TAINT_ERROR_INJECT ? 'E' : ' ', tainted & TAINT_HVM_FEP ? 'H' : ' ', - tainted & TAINT_CPU_OUT_OF_SPEC ? 'S' : ' '); + tainted & TAINT_CPU_OUT_OF_SPEC ? 'S' : ' ', + tainted & TAINT_ERROR_SMOC ? 'A' : ' '); } else { diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h index 9b19679caeb1..4b17f1344732 100644 --- a/xen/include/public/sysctl.h +++ b/xen/include/public/sysctl.h @@ -1180,6 +1180,7 @@ struct xen_sysctl_cpu_policy { }; typedef struct xen_sysctl_cpu_policy xen_sysctl_cpu_policy_t; DEFINE_XEN_GUEST_HANDLE(xen_sysctl_cpu_policy_t); + #endif #if defined(__arm__) || defined (__aarch64__) @@ -1201,6 +1202,13 @@ struct xen_sysctl_dt_overlay { }; #endif +struct xen_sysctl_test_smoc { + uint32_t tests; /* IN: bitmap with selected tests to execute. */ +#define XEN_SYSCTL_TEST_SMOC_INSN_REPL (1U << 0) +#define XEN_SYSCTL_TEST_SMOC_ALL (XEN_SYSCTL_TEST_SMOC_INSN_REPL) + uint32_t results; /* OUT: test result: 1 -> success, 0 -> failure. */ +}; + struct xen_sysctl { uint32_t cmd; #define XEN_SYSCTL_readconsole 1 @@ -1232,6 +1240,7 @@ struct xen_sysctl { /* #define XEN_SYSCTL_set_parameter 28 */ #define XEN_SYSCTL_get_cpu_policy 29 #define XEN_SYSCTL_dt_overlay 30 +#define XEN_SYSCTL_test_smoc 31 uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */ union { struct xen_sysctl_readconsole readconsole; @@ -1259,6 +1268,7 @@ struct xen_sysctl { struct xen_sysctl_cpu_levelling_caps cpu_levelling_caps; struct xen_sysctl_cpu_featureset cpu_featureset; struct xen_sysctl_livepatch_op livepatch; + struct xen_sysctl_test_smoc test_smoc; #if defined(__i386__) || defined(__x86_64__) struct xen_sysctl_cpu_policy cpu_policy; #endif diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h index 1793be5b6b89..575431e4bd38 100644 --- a/xen/include/xen/lib.h +++ b/xen/include/xen/lib.h @@ -167,6 +167,7 @@ uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c); #define TAINT_HVM_FEP (1u << 3) #define TAINT_MACHINE_INSECURE (1u << 4) #define TAINT_CPU_OUT_OF_SPEC (1u << 5) +#define TAINT_ERROR_SMOC (1U << 6) extern unsigned int tainted; #define TAINT_STRING_MAX_LEN 20 extern char *print_tainted(char *str);