Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030425AbVLNEK3 (ORCPT ); Tue, 13 Dec 2005 23:10:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030434AbVLNEK3 (ORCPT ); Tue, 13 Dec 2005 23:10:29 -0500 Received: from zproxy.gmail.com ([64.233.162.205]:23160 "EHLO zproxy.gmail.com") by vger.kernel.org with ESMTP id S1030425AbVLNEK2 convert rfc822-to-8bit (ORCPT ); Tue, 13 Dec 2005 23:10:28 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=abSzHq0BLLou4G+ZweHozwaHH+GudMqfNZRND0Ox9A9zTd8XvkbKHqs6bE6BLq+WcXjMp8rADeYaPYMKsrRRkjGrjNavlRdHOrxS7DuwaNol+spmXEbOZ//XXP0UY3nBlcYdjFCfrJjo7gk50VeoPBJ0KYupD1Nxgg67UFRVADs= Message-ID: <81083a450512132010t2596046bsf7a36f85df19b89c@mail.gmail.com> Date: Wed, 14 Dec 2005 09:40:27 +0530 From: Ashutosh Naik To: Rusty Russell Subject: Re: [RFC][PATCH] Prevent overriding of Symbols in the Kernel, avoiding Undefined behaviour Cc: Jesper Juhl , anandhkrishnan@yahoo.co.in, linux-kernel@vger.kernel.org, rth@redhat.com, akpm@osdl.org, Greg KH , alan@lxorguk.ukuu.org.uk In-Reply-To: <1134525816.30383.13.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <81083a450512120439h69ccf938m12301985458ea69f@mail.gmail.com> <1134424878.22036.13.camel@localhost.localdomain> <81083a450512130626x417d86c9w31f300555c99fdb2@mail.gmail.com> <9a8748490512130849o73c14313l166e6dd360f32d70@mail.gmail.com> <1134525816.30383.13.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2769 Lines: 79 On 12/14/05, Rusty Russell wrote: > Patch looks good! A few nits still: Have resolved all the nits ( hopefully :) ) > We already do this to resolve (more) symbols, so I don't see it as a > problem. However, I believe that lock is redundant here: we need both > locks to write the list, but either is sufficient for reading, and we > already hold the sem. Ya, the lock is redundant here, as we are already inside a semaphore. Signed-off-by: Ashutosh Naik Signed-off-by: Anand Krishnan --- linux-2.6.15-rc5/kernel/module.c.orig 2005-12-14 09:27:53.000000000 +0530 +++ linux-2.6.15-rc5/kernel/module.c 2005-12-14 09:18:31.000000000 +0530 @@ -1204,6 +1204,39 @@ void *__symbol_get(const char *symbol) } EXPORT_SYMBOL_GPL(__symbol_get); +/* + * Ensure that an exported symbol [global namespace] does not already exist + * in the Kernel or in some other modules exported symbol table. + */ +static int verify_export_symbols(struct module *mod) +{ + const char *name = NULL; + unsigned long i, ret = 0; + struct module *owner; + const unsigned long *crc; + + for (i = 0; i < mod->num_syms; i++) + if (!__find_symbol(mod->syms[i].name, &owner, &crc, 1)) { + name = mod->syms[i].name; + ret = -ENOEXEC; + goto dup; + } + + for (i = 0; i < mod->num_gpl_syms; i++) + if (!__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) { + name = mod->gpl_syms[i].name; + ret = -ENOEXEC; + goto dup; + } + +dup: + if (ret) + printk(KERN_ERR "%s: exports duplicate symbol %s (owned by %s)\n", + mod->name, name, module_name(owner)); + + return ret; +} + /* Change all symbols so that sh_value encodes the pointer directly. */ static int simplify_symbols(Elf_Shdr *sechdrs, unsigned int symindex, @@ -1767,6 +1800,12 @@ static struct module *load_module(void _ goto cleanup; } + /* Find duplicate symbols */ + err = verify_export_symbols(mod); + + if (err < 0) + goto cleanup; + /* Set up and sort exception table */ mod->num_exentries = sechdrs[exindex].sh_size / sizeof(*mod->extable); mod->extable = extable = (void *)sechdrs[exindex].sh_addr; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/