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 BCFC8C352A1 for ; Thu, 10 Mar 2022 14:33:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244200AbiCJOdG (ORCPT ); Thu, 10 Mar 2022 09:33:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343810AbiCJObW (ORCPT ); Thu, 10 Mar 2022 09:31:22 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ACDE2DF62; Thu, 10 Mar 2022 06:27:35 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 12DCBB82544; Thu, 10 Mar 2022 14:27:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34CCDC340EB; Thu, 10 Mar 2022 14:27:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646922445; bh=89JcRwzpPQWsm4ynWokjCyskjgS1HkJfGu3hLUmkuPM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sRMxG2abW2gLpYTzu8OA3jsQye2Ijxtn0rEHiR1IXoV92E80eHlUhnqcwEvhf35w/ PxH5/trTC0IkOEKFngMmWvqr03xzMbQ7V+er0rTXc4w04C97Mcsd2dPAZnaTjKjj/X nCFB4Xen03w/Cc4DpSZggTviRcJN/nE+CWpvQDCc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josh Poimboeuf , Borislav Petkov , Thomas Gleixner , Frank van der Linden Subject: [PATCH 5.4 06/33] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Date: Thu, 10 Mar 2022 15:19:07 +0100 Message-Id: <20220310140808.933873567@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310140808.741682643@linuxfoundation.org> References: <20220310140808.741682643@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Josh Poimboeuf commit 44a3918c8245ab10c6c9719dd12e7a8d291980d8 upstream. With unprivileged eBPF enabled, eIBRS (without retpoline) is vulnerable to Spectre v2 BHB-based attacks. When both are enabled, print a warning message and report it in the 'spectre_v2' sysfs vulnerabilities file. Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Reviewed-by: Thomas Gleixner [fllinden@amazon.com: backported to 5.4] Signed-off-by: Frank van der Linden Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++------ include/linux/bpf.h | 12 ++++++++++++ kernel/sysctl.c | 8 ++++++++ 3 files changed, 49 insertions(+), 6 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -31,6 +31,7 @@ #include #include #include +#include #include "cpu.h" @@ -607,6 +608,16 @@ static inline const char *spectre_v2_mod static inline const char *spectre_v2_module_string(void) { return ""; } #endif +#define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" + +#ifdef CONFIG_BPF_SYSCALL +void unpriv_ebpf_notify(int new_state) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && !new_state) + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); +} +#endif + static inline bool match_option(const char *arg, int arglen, const char *opt) { int len = strlen(opt); @@ -951,6 +962,9 @@ static void __init spectre_v2_select_mit break; } + if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); + if (spectre_v2_in_eibrs_mode(mode)) { /* Force it so VMEXIT will restore correctly */ x86_spec_ctrl_base |= SPEC_CTRL_IBRS; @@ -1698,6 +1712,20 @@ static char *ibpb_state(void) return ""; } +static ssize_t spectre_v2_show_state(char *buf) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); + + return sprintf(buf, "%s%s%s%s%s%s\n", + spectre_v2_strings[spectre_v2_enabled], + ibpb_state(), + boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", + stibp_state(), + boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", + spectre_v2_module_string()); +} + static ssize_t srbds_show_state(char *buf) { return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]); @@ -1723,12 +1751,7 @@ static ssize_t cpu_show_common(struct de return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]); case X86_BUG_SPECTRE_V2: - return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], - ibpb_state(), - boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", - stibp_state(), - boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", - spectre_v2_module_string()); + return spectre_v2_show_state(buf); case X86_BUG_SPEC_STORE_BYPASS: return sprintf(buf, "%s\n", ssb_strings[ssb_mode]); --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -751,6 +751,12 @@ int bpf_prog_test_run_skb(struct bpf_pro int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr); + +static inline bool unprivileged_ebpf_enabled(void) +{ + return !sysctl_unprivileged_bpf_disabled; +} + #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { @@ -881,6 +887,12 @@ static inline int bpf_prog_test_run_flow { return -ENOTSUPP; } + +static inline bool unprivileged_ebpf_enabled(void) +{ + return false; +} + #endif /* CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get_type(u32 ufd, --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -251,6 +251,11 @@ static int sysrq_sysctl_handler(struct c #endif #ifdef CONFIG_BPF_SYSCALL + +void __weak unpriv_ebpf_notify(int new_state) +{ +} + static int bpf_unpriv_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { @@ -268,6 +273,9 @@ static int bpf_unpriv_handler(struct ctl return -EPERM; *(int *)table->data = unpriv_enable; } + + unpriv_ebpf_notify(unpriv_enable); + return ret; } #endif