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 3AA3DC43219 for ; Wed, 9 Mar 2022 16:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233017AbiCIQCl (ORCPT ); Wed, 9 Mar 2022 11:02:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234168AbiCIQCd (ORCPT ); Wed, 9 Mar 2022 11:02:33 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB1C117B0C7; Wed, 9 Mar 2022 08:01:24 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 7A25361670; Wed, 9 Mar 2022 16:01:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81B62C340E8; Wed, 9 Mar 2022 16:01:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646841683; bh=B8Kqgr1X+xDFQnu3Mxsih+Dcynf9OwVEriW613XzwTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mS+5p8bwrI6zvpwxyYlOilJipNzBxNiQQwEjb5IsVxNq1FCTS8xY9cPkKeFqzG/rg rSenwaIhDoQqvufkZ/uQSTmmJbzU85QAQ3eB3xUTgKJaUnMa2FwPJUUHVdk58MUCrH 5ygQD7m5giCgOVrIeVqxGwkiZdZpeEG50jb6fijY= 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 , Ben Hutchings Subject: [PATCH 4.9 12/24] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Date: Wed, 9 Mar 2022 16:59:25 +0100 Message-Id: <20220309155856.661941717@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220309155856.295480966@linuxfoundation.org> References: <20220309155856.295480966@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 4.19] Signed-off-by: Frank van der Linden [bwh: Backported to 4.9: adjust context] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++------ include/linux/bpf.h | 11 +++++++++++ kernel/sysctl.c | 8 ++++++++ 3 files changed, 48 insertions(+), 6 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "cpu.h" @@ -606,6 +607,16 @@ 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); @@ -949,6 +960,9 @@ 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; @@ -1686,6 +1700,20 @@ 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]); @@ -1708,12 +1736,7 @@ 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 @@ -295,6 +295,11 @@ static inline void bpf_long_memcpy(void /* verify correctness of eBPF program */ int bpf_check(struct bpf_prog **fp, union bpf_attr *attr); + +static inline bool unprivileged_ebpf_enabled(void) +{ + return !sysctl_unprivileged_bpf_disabled; +} #else static inline void bpf_register_prog_type(struct bpf_prog_type_list *tl) { @@ -322,6 +327,12 @@ static inline struct bpf_prog *bpf_prog_ { return ERR_PTR(-EOPNOTSUPP); } + +static inline bool unprivileged_ebpf_enabled(void) +{ + return false; +} + #endif /* CONFIG_BPF_SYSCALL */ /* verifier prototypes for helper functions called from eBPF programs */ --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -222,6 +222,11 @@ 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) { @@ -239,6 +244,9 @@ static int bpf_unpriv_handler(struct ctl return -EPERM; *(int *)table->data = unpriv_enable; } + + unpriv_ebpf_notify(unpriv_enable); + return ret; } #endif