From patchwork Wed Aug 21 11:49:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Matthias_M=C3=A4nnich?= X-Patchwork-Id: 11106483 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4149A1813 for ; Wed, 21 Aug 2019 11:54:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1624F2339E for ; Wed, 21 Aug 2019 11:54:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vkvKel/T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726858AbfHULyW (ORCPT ); Wed, 21 Aug 2019 07:54:22 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:33490 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727696AbfHULyU (ORCPT ); Wed, 21 Aug 2019 07:54:20 -0400 Received: by mail-qk1-f201.google.com with SMTP id m6so1869381qki.0 for ; Wed, 21 Aug 2019 04:54:19 -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=YVmpgulJe1j8ZxI/z8q9REM9ff/53N3ph4WhYI1NbSw=; b=vkvKel/Ty5vdgEXVJOty1nSV+9zHvdCwk5xEsGWFyO1yXtrcnw06a1J4xduIE/D41b b17f/f9VC9Hycv/jEF5X1L8iOedLWQOsmZo5OZDT4NKG8/jV6vUb0jjqKswEH12FBIbc Up37+2gxNc0wWe3+2Ipt1QMXC6LQH7hM/pnWafDGbSM0YSSPwKU2BK27Ijh8WPOMCCVq 0ANg0OWnVfXpX9p5UZi6Q1tmxfSu/jwgsT8qmv0jn6VS5FGVz7l3bCVqGT5QCgJcsDIj 9HkSz7IHY98wAfYjEBVsuupuuoPmPaM6qfu/E7DtfKRA0IJtCZWUhSUWdUPTfK/iIi8n 7cVA== 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=YVmpgulJe1j8ZxI/z8q9REM9ff/53N3ph4WhYI1NbSw=; b=rQif+ck3t5EpcLHQqB53+RtggZCwWjsgDidmbZZI9x2LJsgF5QG3TkKbvKi3xIIGWe J0ipW7JXYgXcvy4v1chP3wN1iDomUNJRDGHfburZgbQaF7UQbOMD3ARZ8ztxKjVsdOJG OlAmO2HnCpqDhRie9o+6LDpgAyJXLOE2SyJCSH3lWaQWAf25uGbZw+pIIsVKPA0VhikQ O5me6jSjRJHhsjFvM8WAXBpv1ptID0N76d2UWAKkMmZzVuzf04H9+Km+e++Ugh+kQmB4 cO7BEg4z72sAnD6yXN19DxV3CPBOPcMZ5ZPIrF4Gn3pAVwiLZZqslHMXQA+3WXKBWR0v Cq5g== X-Gm-Message-State: APjAAAWGLIuKvN+TMEliCzlvbowsM8bJ8fu6L64ps/XRgKI6mV/S76xD wwz7S6ofOpMXZh7H+LT+McCJfwrMDGqsxA== X-Google-Smtp-Source: APXvYqxAyh6WyYN0U6MnqiCNvPpLjzr9zPgSKWKWLsEuukLq9ZLrKuMMJ2/SMkJRvkBQbMrnKQd6mI8bZHfS/A== X-Received: by 2002:a0c:ba0b:: with SMTP id w11mr17684872qvf.71.1566388458563; Wed, 21 Aug 2019 04:54:18 -0700 (PDT) Date: Wed, 21 Aug 2019 12:49:18 +0100 In-Reply-To: <20190821114955.12788-1-maennich@google.com> Message-Id: <20190821114955.12788-4-maennich@google.com> Mime-Version: 1.0 References: <20190813121733.52480-1-maennich@google.com> <20190821114955.12788-1-maennich@google.com> X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH v3 03/11] module: add support for symbol namespaces. From: Matthias Maennich To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, maennich@google.com, arnd@arndb.de, geert@linux-m68k.org, gregkh@linuxfoundation.org, hpa@zytor.com, jeyu@kernel.org, joel@joelfernandes.org, kstewart@linuxfoundation.org, linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-modules@vger.kernel.org, linux-scsi@vger.kernel.org, linux-usb@vger.kernel.org, lucas.de.marchi@gmail.com, maco@android.com, maco@google.com, michal.lkml@markovi.net, mingo@redhat.com, oneukum@suse.com, pombredanne@nexb.com, sam@ravnborg.org, sspatil@google.com, stern@rowland.harvard.edu, tglx@linutronix.de, usb-storage@lists.one-eyed-alien.net, x86@kernel.org, yamada.masahiro@socionext.com, Michael Ellerman , Andrew Morton , Ard Biesheuvel Sender: owner-linux-modules@vger.kernel.org Precedence: bulk List-ID: The EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL() macros can be used to export a symbol to a specific namespace. There are no _GPL_FUTURE and _UNUSED variants because these are currently unused, and I'm not sure they are necessary. I didn't add EXPORT_SYMBOL_NS() for ASM exports; this patch sets the namespace of ASM exports to NULL by default. In case of relative references, it will be relocatable to NULL. If there's a need, this should be pretty easy to add. A module that wants to use a symbol exported to a namespace must add a MODULE_IMPORT_NS() statement to their module code; otherwise, modpost will complain when building the module, and the kernel module loader will emit an error and fail when loading the module. MODULE_IMPORT_NS() adds a modinfo tag 'import_ns' to the module. That tag can be observed by the modinfo command, modpost and kernel/module.c at the time of loading the module. The ELF symbols are renamed to include the namespace with an asm label; for example, symbol 'usb_stor_suspend' in namespace USB_STORAGE becomes 'usb_stor_suspend.USB_STORAGE'. This allows modpost to do namespace checking, without having to go through all the effort of parsing ELF and relocation records just to get to the struct kernel_symbols. On x86_64 I saw no difference in binary size (compression), but at runtime this will require a word of memory per export to hold the namespace. An alternative could be to store namespaced symbols in their own section and use a separate 'struct namespaced_kernel_symbol' for that section, at the cost of making the module loader more complex. Co-developed-by: Martijn Coenen Signed-off-by: Martijn Coenen Reviewed-by: Greg Kroah-Hartman Signed-off-by: Matthias Maennich --- include/asm-generic/export.h | 6 +-- include/linux/export.h | 85 ++++++++++++++++++++++++++++++------ include/linux/module.h | 2 + kernel/module.c | 43 ++++++++++++++++++ 4 files changed, 120 insertions(+), 16 deletions(-) diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h index 63f54907317b..e2b5d0f569d3 100644 --- a/include/asm-generic/export.h +++ b/include/asm-generic/export.h @@ -17,11 +17,11 @@ .macro __put, val, name #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS - .long \val - ., \name - . + .long \val - ., \name - ., 0 - . #elif defined(CONFIG_64BIT) - .quad \val, \name + .quad \val, \name, 0 #else - .long \val, \name + .long \val, \name, 0 #endif .endm diff --git a/include/linux/export.h b/include/linux/export.h index 28a4d2150689..8e12e05444d1 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -20,6 +20,8 @@ extern struct module __this_module; #ifdef CONFIG_MODULES +#define NS_SEPARATOR "." + #if defined(__KERNEL__) && !defined(__GENKSYMS__) #ifdef CONFIG_MODVERSIONS /* Mark the CRC weak since genksyms apparently decides not to @@ -49,6 +51,16 @@ extern struct module __this_module; * absolute relocations that require runtime processing on relocatable * kernels. */ +#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ + __ADDRESSABLE(sym) \ + asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ + " .balign 4 \n" \ + "__ksymtab_" #sym NS_SEPARATOR #ns ": \n" \ + " .long " #sym "- . \n" \ + " .long __kstrtab_" #sym "- . \n" \ + " .long __kstrtab_ns_" #sym "- . \n" \ + " .previous \n") + #define __KSYMTAB_ENTRY(sym, sec) \ __ADDRESSABLE(sym) \ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \ @@ -56,32 +68,53 @@ extern struct module __this_module; "__ksymtab_" #sym ": \n" \ " .long " #sym "- . \n" \ " .long __kstrtab_" #sym "- . \n" \ + " .long 0 - . \n" \ " .previous \n") struct kernel_symbol { int value_offset; int name_offset; + int namespace_offset; }; #else +#define __KSYMTAB_ENTRY_NS(sym, sec, ns) \ + static const struct kernel_symbol __ksymtab_##sym##__##ns \ + asm("__ksymtab_" #sym NS_SEPARATOR #ns) \ + __attribute__((section("___ksymtab" sec "+" #sym), used)) \ + __aligned(sizeof(void *)) \ + = { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym} + #define __KSYMTAB_ENTRY(sym, sec) \ static const struct kernel_symbol __ksymtab_##sym \ + asm("__ksymtab_" #sym) \ __attribute__((section("___ksymtab" sec "+" #sym), used)) \ __aligned(sizeof(void *)) \ - = { (unsigned long)&sym, __kstrtab_##sym } + = { (unsigned long)&sym, __kstrtab_##sym, NULL } struct kernel_symbol { unsigned long value; const char *name; + const char *namespace; }; #endif -/* For every exported symbol, place a struct in the __ksymtab section */ -#define ___EXPORT_SYMBOL(sym, sec) \ +#define ___export_symbol_common(sym, sec) \ extern typeof(sym) sym; \ __CRC_SYMBOL(sym, sec) \ static const char __kstrtab_##sym[] \ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ - = #sym; \ + = #sym \ + +/* For every exported symbol, place a struct in the __ksymtab section */ +#define ___EXPORT_SYMBOL_NS(sym, sec, ns) \ + ___export_symbol_common(sym, sec); \ + static const char __kstrtab_ns_##sym[] \ + __attribute__((section("__ksymtab_strings"), used, aligned(1))) \ + = #ns; \ + __KSYMTAB_ENTRY_NS(sym, sec, ns) + +#define ___EXPORT_SYMBOL(sym, sec) \ + ___export_symbol_common(sym, sec); \ __KSYMTAB_ENTRY(sym, sec) #if defined(__DISABLE_EXPORTS) @@ -91,6 +124,7 @@ struct kernel_symbol { * be reused in other execution contexts such as the UEFI stub or the * decompressor. */ +#define __EXPORT_SYMBOL_NS(sym, sec, ns) #define __EXPORT_SYMBOL(sym, sec) #elif defined(CONFIG_TRIM_UNUSED_KSYMS) @@ -117,18 +151,26 @@ struct kernel_symbol { #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec) #define __cond_export_sym_0(sym, sec) /* nothing */ +#define __EXPORT_SYMBOL_NS(sym, sec, ns) \ + __ksym_marker(sym); \ + __cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym)) +#define __cond_export_ns_sym(sym, sec, ns, conf) \ + ___cond_export_ns_sym(sym, sec, ns, conf) +#define ___cond_export_ns_sym(sym, sec, ns, enabled) \ + __cond_export_ns_sym_##enabled(sym, sec, ns) +#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns) +#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */ + #else +#define __EXPORT_SYMBOL_NS ___EXPORT_SYMBOL_NS #define __EXPORT_SYMBOL ___EXPORT_SYMBOL #endif -#define EXPORT_SYMBOL(sym) \ - __EXPORT_SYMBOL(sym, "") - -#define EXPORT_SYMBOL_GPL(sym) \ - __EXPORT_SYMBOL(sym, "_gpl") - -#define EXPORT_SYMBOL_GPL_FUTURE(sym) \ - __EXPORT_SYMBOL(sym, "_gpl_future") +#define EXPORT_SYMBOL(sym) __EXPORT_SYMBOL(sym, "") +#define EXPORT_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_gpl") +#define EXPORT_SYMBOL_GPL_FUTURE(sym) __EXPORT_SYMBOL(sym, "_gpl_future") +#define EXPORT_SYMBOL_NS(sym, ns) __EXPORT_SYMBOL_NS(sym, "", ns) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) __EXPORT_SYMBOL_NS(sym, "_gpl", ns) #ifdef CONFIG_UNUSED_SYMBOLS #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused") @@ -138,11 +180,28 @@ struct kernel_symbol { #define EXPORT_UNUSED_SYMBOL_GPL(sym) #endif -#endif /* __GENKSYMS__ */ +#endif /* __KERNEL__ && !__GENKSYMS__ */ + +#if defined(__GENKSYMS__) +/* + * When we're running genksyms, ignore the namespace and make the _NS + * variants look like the normal ones. There are two reasons for this: + * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro + * argument is itself not expanded because it's always tokenized or + * concatenated; but when running genksyms, a blank definition of the + * macro does allow the argument to be expanded; if a namespace + * happens to collide with a #define, this can cause issues. + * 2) There's no need to modify genksyms to deal with the _NS variants + */ +#define EXPORT_SYMBOL_NS(sym, ns) EXPORT_SYMBOL(sym) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) EXPORT_SYMBOL_GPL(sym) +#endif #else /* !CONFIG_MODULES... */ #define EXPORT_SYMBOL(sym) +#define EXPORT_SYMBOL_NS(sym, ns) +#define EXPORT_SYMBOL_NS_GPL(sym, ns) #define EXPORT_SYMBOL_GPL(sym) #define EXPORT_SYMBOL_GPL_FUTURE(sym) #define EXPORT_UNUSED_SYMBOL(sym) diff --git a/include/linux/module.h b/include/linux/module.h index 1455812dd325..b3611e749f72 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -280,6 +280,8 @@ struct notifier_block; #ifdef CONFIG_MODULES +#define MODULE_IMPORT_NS(ns) MODULE_INFO(import_ns, #ns) + extern int modules_disabled; /* for sysctl */ /* Get/put a kernel symbol (calls must be symmetric) */ void *__symbol_get(const char *symbol); diff --git a/kernel/module.c b/kernel/module.c index a23067907169..57e8253f2251 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -544,6 +544,15 @@ static const char *kernel_symbol_name(const struct kernel_symbol *sym) #endif } +static const char *kernel_symbol_namespace(const struct kernel_symbol *sym) +{ +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS + return offset_to_ptr(&sym->namespace_offset); +#else + return sym->namespace; +#endif +} + static int cmp_name(const void *va, const void *vb) { const char *a; @@ -1379,6 +1388,34 @@ static inline int same_magic(const char *amagic, const char *bmagic, } #endif /* CONFIG_MODVERSIONS */ +static char *get_modinfo(const struct load_info *info, const char *tag); +static char *get_next_modinfo(const struct load_info *info, const char *tag, + char *prev); + +static int verify_namespace_is_imported(const struct load_info *info, + const struct kernel_symbol *sym, + struct module *mod) +{ + const char *namespace; + char *imported_namespace; + + namespace = kernel_symbol_namespace(sym); + if (namespace) { + imported_namespace = get_modinfo(info, "import_ns"); + while (imported_namespace) { + if (strcmp(namespace, imported_namespace) == 0) + return 0; + imported_namespace = get_next_modinfo( + info, "import_ns", imported_namespace); + } + pr_err("%s: module uses symbol (%s) from namespace %s, but does not import it.\n", + mod->name, kernel_symbol_name(sym), namespace); + return -EINVAL; + } + return 0; +} + + /* Resolve a symbol for this module. I.e. if we find one, record usage. */ static const struct kernel_symbol *resolve_symbol(struct module *mod, const struct load_info *info, @@ -1413,6 +1450,12 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, goto getname; } + err = verify_namespace_is_imported(info, sym, mod); + if (err) { + sym = ERR_PTR(err); + goto getname; + } + getname: /* We must make copy under the lock if we failed to get ref. */ strncpy(ownername, module_name(owner), MODULE_NAME_LEN);