From patchwork Thu Apr 8 18:28:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 12192241 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=-16.7 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 5F82DC433B4 for ; Thu, 8 Apr 2021 18:32:29 +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 DC443610FC for ; Thu, 8 Apr 2021 18:32:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC443610FC 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=Lko7qgz7uL/q0gFKxWNfpuy0W1oR79lNAzAI+XUlHz4=; b=bsQEO5rPMaRA// EaWhCJEykIH/51OYlWk8zPX7dY/82gXCjr+GV4eBfV3nkNCtaOGrGMa5z2M607aFkhR4G7bKwCSJ9 e/E9/CAVHql375K5pBtYFbRhZXDd5tme8OC8PGMqAz7DudPFddHL5Ie3msbu+qXQk2cIUAXjEYSik DMPj/srEPtim17qAoF1pUVX+BlQjfJhwVjrl8SnnrFCMvQC6Mte3bmMYJzXt2CUaMpc3rfROClkOR vT8ZiH07ogbDR9kvhHyF5jZPy+7++pIaPJ5uJv43rua4GvpsozirbO8yn7c9f6QX+cTj66JmcL7kV ZeyKia/zs/NlN5qsmGRQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lUZPx-008v78-3M; Thu, 08 Apr 2021 18:30:14 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lUZOt-008uht-03 for linux-arm-kernel@lists.infradead.org; Thu, 08 Apr 2021 18:29:09 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id v2so586943ybc.17 for ; Thu, 08 Apr 2021 11:29:00 -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=qNLGON3mLEW9otlCYITUwcgh/bW+ooEbGJnw36Nqnno=; b=jj7kg+VOYnwmWzkTWEHiW28jPkIwiSNlmYCpDvaVmnqrHmBOyAOIMYPWJ9h864B4wy Tzp0pjqCpebrLADZgh91W+KKB8eGueD1VwBS6L7cebE7ZSkkUJu44191T9NS6Rskdh0h 8KxnMbVMi9us5lmvFv05UFsGi1dICU0/jOW35jW1yFDSqWjFoKWggx118j+DDE3/RxML zsfSf8gO1o/pVNO2RMm+vd+3gL61iabM9gmKVtTjnQFryvd6INtxjocfZiBVqnr7RGy/ cE5ecHhNG8V4CRTzylPDxAIUG1JiZs88nEOCENsfA99dniQCG6exDwniRiS5DuiKcDZa k0/Q== 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=qNLGON3mLEW9otlCYITUwcgh/bW+ooEbGJnw36Nqnno=; b=LI4rr7t/CekpnTSmnBRjqyi6KJB/BmtiJzvTKX/vhJDa20qvIp/YPHT933IAc7JUAT 0Ir7hfXrx1cm6xSDVoBQReXReZWxOj6pahSJsGe++MB0XqVAH6yNEQMh57bh3LBWrphG BS6LOZ4ObrqBSilr/iWWP4fBYMSBlKLMmOafTrAukRi41jNiYvUFuBOmZWSZmeoRuwJW 5ptuNvtjppOe/ndDSNvBEvvCqByNFNEgyisbUk8g+tWujChoB5NAgpBbncz2DrOov7Of wtyWW+6yr0YGyV91NfnzjFlEVEJ0ApzSvyAmxLwRXQACWa2hSmyLivCb88l0+HwuXN6v 9TlA== X-Gm-Message-State: AOAM530m49MLIAXwChd+jNsQIWB9VdP78IAOVry/J9LNOK6X/UoSDllR EoE8GpkCZ8UWnSzf6Qnc1k3yYwVXTSfeLKJvU4s= X-Google-Smtp-Source: ABdhPJxUVsuqAxqz+Uc34PB7dmpMvtjLBCQlu4buaoD1UTMPY6dYbIzL2DM8WBBiz1+HV0EZ0aw7CIFzq9DHWz0IVJg= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:3560:8505:40a2:e021]) (user=samitolvanen job=sendgmr) by 2002:a25:360a:: with SMTP id d10mr13411630yba.473.1617906539163; Thu, 08 Apr 2021 11:28:59 -0700 (PDT) Date: Thu, 8 Apr 2021 11:28:32 -0700 In-Reply-To: <20210408182843.1754385-1-samitolvanen@google.com> Message-Id: <20210408182843.1754385-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20210408182843.1754385-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.1.295.g9ea45b61b8-goog Subject: [PATCH v6 07/18] 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 , Peter Zijlstra , Sedat Dilek , Mark Rutland , Catalin Marinas , 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, clang-built-linux@googlegroups.com, Sami Tolvanen X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210408_192907_145018_5C3812CD X-CRM114-Status: GOOD ( 18.24 ) 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 Tested-by: Nathan Chancellor --- kernel/kallsyms.c | 55 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 50 insertions(+), 5 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 8043a90aa50e..c851ca0ed357 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -161,6 +161,27 @@ 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, i.e. foo() becomes foo$707af9a22804d33c81801f27dcfe489b. + * This causes confusion and potentially breaks user space tools, so we + * strip the suffix from expanded symbol names. + */ +static inline bool cleanup_symbol_name(char *s) +{ + char *res; + + res = strrchr(s, '$'); + if (res) + *res = '\0'; + + return res != NULL; +} +#else +static inline bool cleanup_symbol_name(char *s) { return false; } +#endif + /* Lookup the address for this symbol. Returns 0 if not found. */ unsigned long kallsyms_lookup_name(const char *name) { @@ -173,6 +194,9 @@ 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 +327,9 @@ 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 +342,16 @@ 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 +362,23 @@ 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 +390,16 @@ 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. */