From patchwork Thu Mar 18 17:11:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12148749 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DB34C433DB for ; Thu, 18 Mar 2021 17:14:21 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9FCF864EF2 for ; Thu, 18 Mar 2021 17:14:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9FCF864EF2 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Cc:To:From:Subject:References:Mime-Version: Message-Id:In-Reply-To:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=GWwp9o3n6murfe7jP/dSXmOey5TG6gJR6ZyULXffuQY=; b=BsNK+/pIkR+xDy MFzMsuBWYFnQOL8aOxvUJSgQROlnmmzL0GuR1ZKdJlfKoBHUIOGpn24Flq6Y1EKn+yK7ykG00xa3j T2bGLJo56+ksYl7o9ZkYqbvTEe/G4R4z/XEu+A+crVR77PJenvIPbMnMy6uosEhf8DM0/fEmrQiNq JOiuBzGUUZ6quSuO03n781yweC/HOXNwsSgv0JmmOR986lJNkD7Rst8OC8RHgqXC2QVM4M8cVAPkj O7hzagPsCRoFPMU8Fv6HDMig0Lhayh+gd65az14DQuf/rzTXticoUTBo516HuvslIxzHE39sdCRns X+Y8j31qdkb60ZCmElsg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lMwCN-005gC2-ON; Thu, 18 Mar 2021 17:12:42 +0000 Received: from mail-pj1-x104a.google.com ([2607:f8b0:4864:20::104a]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lMwBJ-005fm6-QH for linux-arm-kernel@lists.infradead.org; Thu, 18 Mar 2021 17:11:35 +0000 Received: by mail-pj1-x104a.google.com with SMTP id z21so20264764pjt.0 for ; Thu, 18 Mar 2021 10:11:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=QoegLXCzdycUycxpIzR40RqHRPa9NLqqSFx528i53Ro=; b=SwdpuVXHhmr5I7uUVGY1EjCm8+fTTbfiNABDrVeBEVmIvbeeIDlt/UhyWnlCaKQm07 OIVzSOKtR3TWxAAi/LnAZiHfEIOEJFpBom+cqUC5mlcbXjV+TWyDtvH30rGq0Gs390D1 gKgHu/2HCL710YS0gubnGCYv6wl8+cDW5YmBKVr3wnbCPMiEX3L6SMXkiSg65Jb4yGk5 6t/YyfLngnf9r/RqZQWnFpYTr8wfMnnp2xedEMcFyg73Q8MHPxOyZplkRYUZtrweMSEb t5YGPopzwnrFjPlk4cXa7Qj0ab6klJPgsRdMebUCuUpOilfqFPZMRnljqiv9zyy4kWwZ kRWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=QoegLXCzdycUycxpIzR40RqHRPa9NLqqSFx528i53Ro=; b=sgWtuA+HbOS24Kl+d86Jy97arZTwSxyxyZfiQuYy7rBc9RjMq9Wux2/YtWrsU0UNmt 93H5enccx8sDB+FfjODpqblScrjTFPe9vs3tucfyYWz+t5WlGYP2rJmXVEYiajm6ArjB mbKowm9zcHlYr5xc2eFJ16fhs3ZlwhkC0CC0/xAatee4ydE7YmG3tzNtgkObukv6ozn/ 3bshXsli2mqKVuGuDBIuO7+ArQyxHZVEKgOTaZzh7sQEyzOcS2LnTT8eA1VZJgGD2AJv 04kS/fqvt3QnzrQ5Gvt9liMzREzeRnlygApq21z15ZrFgre65tjXYexkKyxXUMYoxum/ 8+5Q== X-Gm-Message-State: AOAM530xTUUNI92h54zyTqBIO74pqbegktbtP0Q64JuPxj6jpGkePSs7 URJ8MfJowz5Tq/4PPRStyVr9brfa+VgH1OcxdCU= X-Google-Smtp-Source: ABdhPJx7blCXf2gjM2TRqlPaz7K7KuIqvTaBoVDCfyrUDL1O5jt8iCqoUsRNSsWoTAT2ZRwEgLc0VblPK6SpskXxR50= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:c0d7:a7ba:fb41:a35a]) (user=samitolvanen job=sendgmr) by 2002:aa7:9619:0:b029:1fa:ed79:b724 with SMTP id q25-20020aa796190000b02901faed79b724mr4972560pfg.38.1616087491320; Thu, 18 Mar 2021 10:11:31 -0700 (PDT) Date: Thu, 18 Mar 2021 10:11:01 -0700 In-Reply-To: <20210318171111.706303-1-samitolvanen@google.com> Message-Id: <20210318171111.706303-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20210318171111.706303-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.291.g576ba9dcdaf-goog Subject: [PATCH v2 07/17] kallsyms: strip ThinLTO hashes from static functions From: Sami Tolvanen To: Kees Cook Cc: Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , bpf@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Sami Tolvanen X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210318_171133_938961_5CAB0338 X-CRM114-Status: GOOD ( 18.32 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org With CONFIG_CFI_CLANG and ThinLTO, Clang appends a hash to the names of all static functions not marked __used. This can break userspace tools that don't expect the function name to change, so strip out the hash from the output. Suggested-by: Jack Pham Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- kernel/kallsyms.c | 54 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 8043a90aa50e..17d3a704bafa 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -161,6 +161,26 @@ static unsigned long kallsyms_sym_address(int idx) return kallsyms_relative_base - 1 - kallsyms_offsets[idx]; } +#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN) +/* + * LLVM appends a hash to static function names when ThinLTO and CFI are + * both enabled, which causes confusion and potentially breaks user space + * tools, so we will strip the postfix from expanded symbol names. + */ +static inline char *cleanup_symbol_name(char *s) +{ + char *res = NULL; + + res = strrchr(s, '$'); + if (res) + *res = '\0'; + + return res; +} +#else +static inline char *cleanup_symbol_name(char *s) { return NULL; } +#endif + /* Lookup the address for this symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name) { @@ -173,6 +193,9 @@ unsigned long kallsyms_lookup_name(const char *name) if (strcmp(namebuf, name) == 0) return kallsyms_sym_address(i); + + if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0) + return kallsyms_sym_address(i); } return module_kallsyms_lookup_name(name); } @@ -303,7 +326,9 @@ const char *kallsyms_lookup(unsigned long addr, namebuf, KSYM_NAME_LEN); if (modname) *modname = NULL; - return namebuf; + + ret = namebuf; + goto found; } /* See if it's in a module or a BPF JITed image. */ @@ -316,11 +341,16 @@ const char *kallsyms_lookup(unsigned long addr, if (!ret) ret = ftrace_mod_address_lookup(addr, symbolsize, offset, modname, namebuf); + +found: + cleanup_symbol_name(namebuf); return ret; } int lookup_symbol_name(unsigned long addr, char *symname) { + int res; + symname[0] = '\0'; symname[KSYM_NAME_LEN - 1] = '\0'; @@ -331,15 +361,23 @@ int lookup_symbol_name(unsigned long addr, char *symname) /* Grab name */ kallsyms_expand_symbol(get_symbol_offset(pos), symname, KSYM_NAME_LEN); - return 0; + goto found; } /* See if it's in a module. */ - return lookup_module_symbol_name(addr, symname); + res = lookup_module_symbol_name(addr, symname); + if (res) + return res; + +found: + cleanup_symbol_name(symname); + return 0; } int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name) { + int res; + name[0] = '\0'; name[KSYM_NAME_LEN - 1] = '\0'; @@ -351,10 +389,16 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size, kallsyms_expand_symbol(get_symbol_offset(pos), name, KSYM_NAME_LEN); modname[0] = '\0'; - return 0; + goto found; } /* See if it's in a module. */ - return lookup_module_symbol_attrs(addr, size, offset, modname, name); + res = lookup_module_symbol_attrs(addr, size, offset, modname, name); + if (res) + return res; + +found: + cleanup_symbol_name(name); + return 0; } /* Look up a kernel symbol and return it in a text buffer. */