From patchwork Wed Jul 3 22:11:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yuxuan Luo X-Patchwork-Id: 1956463 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com (client-ip=185.125.189.65; helo=lists.ubuntu.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=patchwork.ozlabs.org) Received: from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4WDvCQ0S9Sz1xqv for ; Thu, 4 Jul 2024 08:12:17 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=lists.ubuntu.com) by lists.ubuntu.com with esmtp (Exim 4.86_2) (envelope-from ) id 1sP8Ct-0005HY-Cs; Wed, 03 Jul 2024 22:12:07 +0000 Received: from smtp-relay-internal-1.internal ([10.131.114.114] helo=smtp-relay-internal-1.canonical.com) by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1sP8Cs-0005HO-Kz for kernel-team@lists.ubuntu.com; Wed, 03 Jul 2024 22:12:06 +0000 Received: from mail-qt1-f199.google.com (mail-qt1-f199.google.com [209.85.160.199]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-1.canonical.com (Postfix) with ESMTPS id 7764B3F0D2 for ; Wed, 3 Jul 2024 22:12:06 +0000 (UTC) Received: by mail-qt1-f199.google.com with SMTP id d75a77b69052e-44659591ce2so75538061cf.3 for ; Wed, 03 Jul 2024 15:12:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720044725; x=1720649525; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=USKe0aEnaOc12ORaDbPlV+TO4Uop3+9Er1GZuFvZjLE=; b=uOo8aoiP01IR0FYKlmC36VDgQbheTX6v9bhOFlAOSo5r0VAVs2Z8HCQzr1D1Ogp1v+ 1MiHNu9pChANfBxIptjyOPTzme+yTZjbkrOpPuvB+ejEkZaKAc8dzxdWB0L7CTUVnU33 v6P0dHc4Eyjk6nOXBCcz3/Ofme/2Z4GKF7nddVmSdeMFni9pYZE4ZIl47Yxtabk5B+d9 RcHe+jhDMzCIT/vfpfFuzm33qLui9XQHnESZdNlXEgDKFd0JI6fwfvwIbg743ZKycFbv nYCf2F9FfTaiILBYSWra3QntPienG7cQUjxyGAFo+FNUfRa1+yCR0LcgV1cQNY+5qsUC fwyQ== X-Gm-Message-State: AOJu0YxLHJ2Eel0K/1XGOoIodwU/W/sHSwDdRBHWBWhibaldtVVYn6gj try06ucxsMEZI5PUSjiJuJSRPF7LPyKqUiojX8LT+b9GTwdmSphAqsFr2vUeiOS6Otq0rsS8/XJ S8jdUfwwsTWrcXZpOvC9KZxkVq6Qjfc5+lMQUSLj8sw0nWL8lqBdhELzL5s1uNSOLEN1vG9l+zT mJJVXKy91Dbg== X-Received: by 2002:ac8:5947:0:b0:446:3c7a:3689 with SMTP id d75a77b69052e-44662e43e17mr157057181cf.43.1720044724757; Wed, 03 Jul 2024 15:12:04 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFeYJnbU7r9Kmhw0AhXZ6Eh3k+9TZysi3j6Yg2WiezNOPalNyB3i2zU5w2UbZOqo3zXgT8M/g== X-Received: by 2002:ac8:5947:0:b0:446:3c7a:3689 with SMTP id d75a77b69052e-44662e43e17mr157057021cf.43.1720044724386; Wed, 03 Jul 2024 15:12:04 -0700 (PDT) Received: from cache-ubuntu.hsd1.nj.comcast.net ([2001:67c:1562:8007::aac:4795]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4465143c93csm54430991cf.52.2024.07.03.15.12.03 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jul 2024 15:12:03 -0700 (PDT) From: Yuxuan Luo To: kernel-team@lists.ubuntu.com Subject: [SRU][Noble][PATCH 1/2] x86/sev: Harden #VC instruction emulation somewhat Date: Wed, 3 Jul 2024 18:11:56 -0400 Message-Id: <20240703221157.1675604-3-yuxuan.luo@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240703221157.1675604-1-yuxuan.luo@canonical.com> References: <20240703221157.1675604-1-yuxuan.luo@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: "Borislav Petkov (AMD)" Compare the opcode bytes at rIP for each #VC exit reason to verify the instruction which raised the #VC exception is actually the right one. Signed-off-by: Borislav Petkov (AMD) Acked-by: Tom Lendacky Link: https://lore.kernel.org/r/20240105101407.11694-1-bp@alien8.de (cherry picked from commit e3ef461af35a8c74f2f4ce6616491ddb355a208f) CVE-2024-25742 Signed-off-by: Yuxuan Luo --- arch/x86/boot/compressed/sev.c | 4 ++ arch/x86/kernel/sev-shared.c | 102 ++++++++++++++++++++++++++++++++- arch/x86/kernel/sev.c | 5 +- 3 files changed, 108 insertions(+), 3 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 4c9b752814177..bea0719d70f2d 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -307,6 +307,10 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code) if (result != ES_OK) goto finish; + result = vc_check_opcode_bytes(&ctxt, exit_code); + if (result != ES_OK) + goto finish; + switch (exit_code) { case SVM_EXIT_RDTSC: case SVM_EXIT_RDTSCP: diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index be2fa2fc02f36..0bd7ccbe87324 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -10,11 +10,15 @@ */ #ifndef __BOOT_COMPRESSED -#define error(v) pr_err(v) -#define has_cpuflag(f) boot_cpu_has(f) +#define error(v) pr_err(v) +#define has_cpuflag(f) boot_cpu_has(f) +#define sev_printk(fmt, ...) printk(fmt, ##__VA_ARGS__) +#define sev_printk_rtl(fmt, ...) printk_ratelimited(fmt, ##__VA_ARGS__) #else #undef WARN #define WARN(condition, format...) (!!(condition)) +#define sev_printk(fmt, ...) +#define sev_printk_rtl(fmt, ...) #endif /* I/O parameters for CPUID-related helpers */ @@ -570,6 +574,7 @@ void __head do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) { unsigned int subfn = lower_bits(regs->cx, 32); unsigned int fn = lower_bits(regs->ax, 32); + u16 opcode = *(unsigned short *)regs->ip; struct cpuid_leaf leaf; int ret; @@ -577,6 +582,10 @@ void __head do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) if (exit_code != SVM_EXIT_CPUID) goto fail; + /* Is it really a CPUID insn? */ + if (opcode != 0xa20f) + goto fail; + leaf.fn = fn; leaf.subfn = subfn; @@ -1167,3 +1176,92 @@ static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) out: return ret; } + +static enum es_result vc_check_opcode_bytes(struct es_em_ctxt *ctxt, + unsigned long exit_code) +{ + unsigned int opcode = (unsigned int)ctxt->insn.opcode.value; + u8 modrm = ctxt->insn.modrm.value; + + switch (exit_code) { + + case SVM_EXIT_IOIO: + case SVM_EXIT_NPF: + /* handled separately */ + return ES_OK; + + case SVM_EXIT_CPUID: + if (opcode == 0xa20f) + return ES_OK; + break; + + case SVM_EXIT_INVD: + if (opcode == 0x080f) + return ES_OK; + break; + + case SVM_EXIT_MONITOR: + if (opcode == 0x010f && modrm == 0xc8) + return ES_OK; + break; + + case SVM_EXIT_MWAIT: + if (opcode == 0x010f && modrm == 0xc9) + return ES_OK; + break; + + case SVM_EXIT_MSR: + /* RDMSR */ + if (opcode == 0x320f || + /* WRMSR */ + opcode == 0x300f) + return ES_OK; + break; + + case SVM_EXIT_RDPMC: + if (opcode == 0x330f) + return ES_OK; + break; + + case SVM_EXIT_RDTSC: + if (opcode == 0x310f) + return ES_OK; + break; + + case SVM_EXIT_RDTSCP: + if (opcode == 0x010f && modrm == 0xf9) + return ES_OK; + break; + + case SVM_EXIT_READ_DR7: + if (opcode == 0x210f && + X86_MODRM_REG(ctxt->insn.modrm.value) == 7) + return ES_OK; + break; + + case SVM_EXIT_VMMCALL: + if (opcode == 0x010f && modrm == 0xd9) + return ES_OK; + + break; + + case SVM_EXIT_WRITE_DR7: + if (opcode == 0x230f && + X86_MODRM_REG(ctxt->insn.modrm.value) == 7) + return ES_OK; + break; + + case SVM_EXIT_WBINVD: + if (opcode == 0x90f) + return ES_OK; + break; + + default: + break; + } + + sev_printk(KERN_ERR "Wrong/unhandled opcode bytes: 0x%x, exit_code: 0x%lx, rIP: 0x%lx\n", + opcode, exit_code, ctxt->regs->ip); + + return ES_UNSUPPORTED; +} diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index eb2873b5eb1bb..e77dbd58ac7b0 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -1740,7 +1740,10 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, struct ghcb *ghcb, unsigned long exit_code) { - enum es_result result; + enum es_result result = vc_check_opcode_bytes(ctxt, exit_code); + + if (result != ES_OK) + return result; switch (exit_code) { case SVM_EXIT_READ_DR7: