From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 005052144A0 for ; Tue, 12 Nov 2024 17:56:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731434187; cv=none; b=aJdqTi0XHEcoYC4yFS2K/CW5N9oDeoKzB+zPyJ9STf4y+wVgKoIv1hter39FmRnD54X/x68HxYkjfPq2xgsLXFeHH+r7UXdkjov8MADyUE1WVM30qbNMK615YXvLcs4l21oQYmGjxgrd2Tu4e9Q1PW1m/74d1v4OW5+s8uzz9J0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731434187; c=relaxed/simple; bh=JWSxFmX0mWdW30jemqkQmnNHt0dCtAUSXXk9eh8by28=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Ij5+kJTnu3QUmD3uVZkAkroDMoR6nqQHJtG1OTOvKyxeGKJeuD21WuxjQbImASesFGzQffXbNDT+u/2Hr3tN5lqC8TGT8MUFwIfjJWm1ImHeXP3Ic6rOmJ1iNPU3kAAbGMq4DQXIbntBOw4SNHvYvNzJnwkefw8Id2DF0nUmcyI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=WvlPBj8g; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WvlPBj8g" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2e9b4a68809so4690348a91.1 for ; Tue, 12 Nov 2024 09:56:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1731434182; x=1732038982; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=b9YTemcNOSBux/pW1rWp64ZP6TCtswrMtsdAWnShfy0=; b=WvlPBj8gpdUpj2RvGrbqV4y8B5AM7v3Sta9FZ16aa9T+8GrNTLB52d+xFBATO/S/7F 44/UTOgIGMyGu97h6M/rlaA6GxZy5n3RMgKaxJJshgS8RoFup9VWCz9dPyjIGgT1P1z/ w7adBvXCFbpoWwKhRWiMhLgdrUxR1EO2SD1j+/xiIucS/SOEZlv4Z/Kq7QdOTukur6c9 tD8FWdnEyGez/u3/+fJcgbNxtKcj3c9e4LxFtyfxd8o1s7cCr2x40Lzsq2UpMmo3IVht GYfNCcxBviPr+YmoXbOU8msFeo/l8xS3/27n+I3tVl7OxV1kkKcxFNVwe1i1rZ33lBJ+ FK7g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1731434182; x=1732038982; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=b9YTemcNOSBux/pW1rWp64ZP6TCtswrMtsdAWnShfy0=; b=bouSwNVR6Zs5KXnu7sktXDEm/WQu1s1Dvc3IuP7vCvSHh633jbINp5tNCo7buSQuZk hEfUz3cyS5/KzU7xRSIrkAycGp8xU1rdDD1oe4a0Upsz2N+c8tyvuH3P0cRaXLtfea2c qWbiTrrEmqnKWxBxsTDHKGmZYqpFOKTEPfNOSbUgFbmjXFwBNBUzgrFfDpYFXQNpSQBV scaRDMypPkjHTGyWVAf9Al8CNh52vyYo0xe09aclUrhYhhKigHRXBMOrvwu5t/+mfmVg GxiqGCzyQMlgZY32Yc2EYsg+c3zysRgdCKJAoR5mzwvfSoieuNIMdoSg8QeeGMZKpByg b7Bg== X-Forwarded-Encrypted: i=1; AJvYcCWaAXTHVF2o0dUx8W3lQ3Czt/6ZfYuQAmeOYJwZIVvnKee2tqiE+BxrwZ1uh7mcSd35FChleLqzNw6RbCA=@vger.kernel.org X-Gm-Message-State: AOJu0YzLJhp2kV5IC/cjfFyde0WmkX7uILMdqmVWSDEEX95nRg5qkJ2P MZhECU/udsO65KTrqJbkRHUy6DlOG9pqA5UO/W30DjM5rHbZjMSHIONVAeayii7FJzfmK4AHIrM zwA== X-Google-Smtp-Source: AGHT+IE5WL7h2XGzNj0qvrasZxftY/gxfWOWiXcQjrdbTbO16lDeHCTWuerM/EDIQ9IuAlYE6FEWQVvgFrY= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:9d:3983:ac13:c240]) (user=seanjc job=sendgmr) by 2002:a17:90b:198c:b0:2d8:8f24:bd8c with SMTP id 98e67ed59e1d1-2e9e493301emr50942a91.0.1731434182424; Tue, 12 Nov 2024 09:56:22 -0800 (PST) Date: Tue, 12 Nov 2024 09:56:20 -0800 In-Reply-To: <20241112092023.GL22801@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241111105430.575636482@infradead.org> <20241112092023.GL22801@noisy.programming.kicks-ass.net> Message-ID: Subject: Re: [RFC][PATCH 0/8] module: Strict per-modname namespaces From: Sean Christopherson To: Peter Zijlstra Cc: mcgrof@kernel.org, x86@kernel.org, hpa@zytor.com, petr.pavlu@suse.com, samitolvanen@google.com, da.gomez@samsung.com, masahiroy@kernel.org, nathan@kernel.org, nicolas@fjasle.eu, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, linux-kbuild@vger.kernel.org, hch@infradead.org, gregkh@linuxfoundation.org Content-Type: text/plain; charset="us-ascii" On Tue, Nov 12, 2024, Peter Zijlstra wrote: > On Mon, Nov 11, 2024 at 04:48:58PM -0800, Sean Christopherson wrote: > > On Mon, Nov 11, 2024, Peter Zijlstra wrote: > > > Hi! > > > > > > Implement a means for exports to be available only to an explicit list of named > > > modules. By explicitly limiting the usage of certain exports, the abuse > > > potential/risk is greatly reduced. > > > > > > The first three 'patches' clean up the existing export namespace code along the > > > same lines of 33def8498fdd ("treewide: Convert macro and uses of __section(foo) > > > to __section("foo")") and for the same reason, it is not desired for the > > > namespace argument to be a macro expansion itself. > > > > > > In fact, the second patch is really only a script, because sending the output > > > to the list is a giant waste of bandwidth. Whoever eventually commits this to a > > > git tree should squash these first three patches. > > > > > > The remainder of the patches introduce the special "MODULE_" > > > namespace, which shall be forbidden from being explicitly imported. A module > > > that matches the simple modname-list will get an implicit import. > > > > > > Lightly tested with something like: > > > > > > git grep -l EXPORT_SYMBOL arch/x86/kvm/ | while read file; > > > do > > > sed -i -e 's/EXPORT_SYMBOL_GPL(\(.[^)]*\))/EXPORT_SYMBOL_GPL_FOR(\1, "kvm,kvm-intel,kvm-amd")/g' $file; > > > done > > > > Heh, darn modules. This will compile just fine, but if the module contains a > > dash, loading the module will fail because scripts/Makefile.lib replaces the dash > > with an underscore the build name. E.g. "kvm-intel" at compile time generates > > kvm-intel.ko, but the actual name of the module as seen by the kernel is kvm_intel. > > I was wondering about that... WTH is kvm doing that? No idea. The naming has been that way since KVM's inception in commit 6aa8b732ca01 ("[PATCH] kvm: userspace interface"). My guess is that either no one noticed, or those who noticed didn't care. FWIW, IMO the kernel build system is the one that's being weird. AFAICT, the '-' => '_' conversion was added so that spinlocks could be placed into unique subsections. Amusingly, it doesn't appear that there are any remaining users of LOCK_SECTION_NAME. commit b5635319d32438ed516568f53013a460ba16e6ee Author: Dave Jones AuthorDate: Fri Feb 8 01:43:23 2002 -0800 Commit: Linus Torvalds CommitDate: Fri Feb 8 01:43:23 2002 -0800 [PATCH] text.lock -> subsection changes. Make spinlocks etc use subsections of their parent sections instead of an ELF section of their own - needed for newer binutils when the parent sector is removed. #define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME #define LOCK_SECTION_START(extra) \ ".subsection 1\n\t" \ extra \ ".ifndef " LOCK_SECTION_NAME "\n\t" \ LOCK_SECTION_NAME ":\n\t" \ ".endif\n" #define LOCK_SECTION_END \ ".previous\n\t" #define __lockfunc __section(".spinlock.text") > I mean, I suppose you can do: "kvm-intel,kvm_intel" but that's somewhat > tedious. This likely needs to be addressed in whatever chunk of code is enforcing the namespaces. The s/-/_ behavior (and vice versa!) is *very* baked into the kernel at this point, e.g. parameqn() will happily parse dashes or underscores for every kernel parameter. As horrific as it is, I think the module namespace needs to do the same, i.e. treat dashes and underscores as one and the same. More historical amusement: commit 8863179c65618844379ef90d4a708293042465c8 Author: Andrew Morton AuthorDate: Sun Feb 2 06:08:27 2003 -0800 Commit: Linus Torvalds CommitDate: Sun Feb 2 06:08:27 2003 -0800 [PATCH] kernel param and KBUILD_MODNAME name-munging mess Patch from: Rusty Russell Mikael Pettersson points out that "-s" gets mangled to "_s" on the kernel command line, even though it turns out not to be a parameter. commit 326e7842d30d5cfc1089b85a7aa63e5c9f3c0a74 Author: Rusty Russell AuthorDate: Sat Dec 14 20:13:11 2002 -0800 Commit: Linus Torvalds CommitDate: Sat Dec 14 20:13:11 2002 -0800 [PATCH] Module Parameter Core Patch This patch is a rewrite of the insmod and boot parameter handling, to unify them. The new format is fairly simple: built on top of __module_param_call there are several helpers, eg "module_param(foo, int, 000)". The final argument is the permissions bits, for exposing parameters in sysfs (if non-zero) at a later stage.