From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f73.google.com (mail-ed1-f73.google.com [209.85.208.73]) (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 8FAEE31197B for ; Thu, 11 Dec 2025 12:59:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765457978; cv=none; b=bHjDOpfAcSSiM7Y1QPQprG7aliH6HCwJxD9ZOtwJ8vHR9IIeKvzznVUkd+PP/PUqsXUGoLqOqjN3Lng0DaMnamGIsFQSyhM1CL6+IX2bKcqzX1tTLRwR1VKUMuVr4cMHJIleDQi7rk/PGMzcbCZpRlqpLIRgma95+wpq32HZrJY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765457978; c=relaxed/simple; bh=+z79bXLoOJ+XZE6osatr9wzGHUsuMYC5kf8Bmab816s=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=s226+pu5CbpfP6v8znFcfz6oZjVZCIoNw8EXsOM1+GnxO0LE6BqInmpgb6yQA8GtTDyLsmd2LzUIU7iI6PYy04y0kygzOj9ZkhJYHATvK9lub+u2KndKf4cih6f6rsn61ipftc1VV/6lOpQWCbmNb9c3zABnSaqFZGWxLYq334Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--smostafa.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=LoQSeB2V; arc=none smtp.client-ip=209.85.208.73 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--smostafa.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="LoQSeB2V" Received: by mail-ed1-f73.google.com with SMTP id 4fb4d7f45d1cf-640b8087663so52944a12.3 for ; Thu, 11 Dec 2025 04:59:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1765457975; x=1766062775; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=r3J1hYN9XMEFmXD/a5v7i5culnnk0CIa5QUwHD0Ft2E=; b=LoQSeB2VWhxRWZb/Wj2hqXYyyhICdTPwk4aNxCWW05g6robsfvJv5Ris0iTKcFci0t 6oD8fncN5B6jLZeOdIk+uKxHnw5A8HmV/IK1UnTcs6tkX3LLF5s80QwU4Lnli7UpFNoE GdGhE18nHv26n8khKeRgtvbwGWy9xog4YW7zileV/u1YfqCBOAoCxjSfGpgFdIAT2hMV cN2Te1VPOf/QuTA+5gEjbblOR53/UfrIe90RlPfj63w4tsY7NcX9+yG3DgqvwF8oPMBE iVOXg93n7dcS2trJ4a9dJ0TZjEPHRm5N8X6bKgrH8pMAW+Ez/rUfHXMc+PXs9iu52RRN KqPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765457975; x=1766062775; 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=r3J1hYN9XMEFmXD/a5v7i5culnnk0CIa5QUwHD0Ft2E=; b=Kgrohx+FBh4ozw9XPeC53oaQSyDfYLpA2Z7vZdSNKaWvRQXdI/BQLk6xDuMCNwG1Ze Ovv1x9bw/baablynD03ofH5y8SWCYGQWSUd5nxXmn7U6v0nukFGkacDuZ7g+SmJlWpGc 1EUcr67aT4Jhkm/D84q9EdtxO/t3iHmTn37NFYeNb2Yl4LkMcx32/DuVJIKsLxawKCOp J2r0WWtfM5tuwbpfg4cRkgjPB2PXu3E4BC/6QeEBZoSwRndNIftvw7qiHT0TGYlKtmoM GOkI9jHvSlg2QVxvSm6Re4mQ3HY36uUrslrOUESyslUO211Rivi5VQkK1peOkVYFgJ59 WSEg== X-Forwarded-Encrypted: i=1; AJvYcCWwMu4L6LFYPlV+gUSE4UnWM5asSkeBp27b/Ai+QXNdYcq7e2uLRzNO5ihpI8yp9XpQ1OKcQQ==@lists.linux.dev X-Gm-Message-State: AOJu0YyEoM3stsx7v1TIPRoN4C7HlOMzO80WKKZOf+PtGG69wwh5F//k fiSZysiT1333n97A6GOlyvLaHSWp6sUfFiJr/O/SfxrptDach/BuRsa04JweL1uqopJjmgN66y6 aMno27yZiK9+juA== X-Google-Smtp-Source: AGHT+IG4CAINMoRrbl1/Lgxz8kmNwjv/bmm/r66kW6sFrhYWMSR/59VpzDrRMyuM6uvP8I+JLx3Vv8a86mrk/g== X-Received: from ejbuz10.prod.google.com ([2002:a17:907:118a:b0:b79:f583:7b35]) (user=smostafa job=prod-delivery.src-stubby-dispatcher) by 2002:a17:907:3c8e:b0:b4b:dd7e:65f2 with SMTP id a640c23a62f3a-b7ce823a835mr725575966b.5.1765457974933; Thu, 11 Dec 2025 04:59:34 -0800 (PST) Date: Thu, 11 Dec 2025 12:59:25 +0000 In-Reply-To: <20251211125928.3258905-1-smostafa@google.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251211125928.3258905-1-smostafa@google.com> X-Mailer: git-send-email 2.52.0.223.gf5cc29aaa4-goog Message-ID: <20251211125928.3258905-2-smostafa@google.com> Subject: [PATCH v4 1/4] iommu: Add page_ext for IOMMU_DEBUG_PAGEALLOC From: Mostafa Saleh To: linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, xiaqinxin@huawei.com, baolu.lu@linux.intel.com, rdunlap@infradead.org, Mostafa Saleh Content-Type: text/plain; charset="UTF-8" Add a new config IOMMU_DEBUG_PAGEALLOC, which registers new data to page_ext. This config will be used by the IOMMU API to track pages mapped in the IOMMU to catch drivers trying to free kernel memory that they still map in their domains, causing all types of memory corruption. This behaviour is disabled by default and can be enabled using kernel cmdline iommu.debug_pagealloc. Signed-off-by: Mostafa Saleh --- .../admin-guide/kernel-parameters.txt | 9 ++++++ drivers/iommu/Kconfig | 19 +++++++++++ drivers/iommu/Makefile | 1 + drivers/iommu/iommu-debug-pagealloc.c | 32 +++++++++++++++++++ include/linux/iommu-debug-pagealloc.h | 17 ++++++++++ mm/page_ext.c | 4 +++ 6 files changed, 82 insertions(+) create mode 100644 drivers/iommu/iommu-debug-pagealloc.c create mode 100644 include/linux/iommu-debug-pagealloc.h diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a8d0afde7f85..d484d9d8d0a4 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2675,6 +2675,15 @@ Kernel parameters 1 - Bypass the IOMMU for DMA. unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. + iommu.debug_pagealloc= + [KNL,EARLY] When CONFIG_IOMMU_DEBUG_PAGEALLOC is set, this + parameter enables the feature at boot time. By default, it + is disabled and the system behaves the same way as a kernel + built without CONFIG_IOMMU_DEBUG_PAGEALLOC. + Format: { "0" | "1" } + 0 - Sanitizer disabled. + 1 - Sanitizer enabled, expect runtime overhead. + io7= [HW] IO7 for Marvel-based Alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig index 99095645134f..f86262b11416 100644 --- a/drivers/iommu/Kconfig +++ b/drivers/iommu/Kconfig @@ -384,6 +384,25 @@ config SPRD_IOMMU Say Y here if you want to use the multimedia devices listed above. +config IOMMU_DEBUG_PAGEALLOC + bool "Debug IOMMU mappings against page allocations" + depends on DEBUG_PAGEALLOC && IOMMU_API && PAGE_EXTENSION + help + This enables a consistency check between the kernel page allocator and + the IOMMU subsystem. It verifies that pages being allocated or freed + are not currently mapped in any IOMMU domain. + + This helps detect DMA use-after-free bugs where a driver frees a page + but forgets to unmap it from the IOMMU, potentially allowing a device + to overwrite memory that the kernel has repurposed. + + These checks are best-effort and may not detect all problems. + + Due to performance overhead, this feature is disabled by default. + You must enable "iommu.debug_pagealloc" from the kernel command + line to activate the runtime checks. + + If unsure, say N. endif # IOMMU_SUPPORT source "drivers/iommu/generic_pt/Kconfig" diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile index 8e8843316c4b..0275821f4ef9 100644 --- a/drivers/iommu/Makefile +++ b/drivers/iommu/Makefile @@ -36,3 +36,4 @@ obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o obj-$(CONFIG_APPLE_DART) += apple-dart.o +obj-$(CONFIG_IOMMU_DEBUG_PAGEALLOC) += iommu-debug-pagealloc.o diff --git a/drivers/iommu/iommu-debug-pagealloc.c b/drivers/iommu/iommu-debug-pagealloc.c new file mode 100644 index 000000000000..4022e9af7f27 --- /dev/null +++ b/drivers/iommu/iommu-debug-pagealloc.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 - Google Inc + * Author: Mostafa Saleh + * IOMMU API debug page alloc sanitizer + */ +#include +#include +#include +#include + +static bool needed; + +struct iommu_debug_metadata { + atomic_t ref; +}; + +static __init bool need_iommu_debug(void) +{ + return needed; +} + +struct page_ext_operations page_iommu_debug_ops = { + .size = sizeof(struct iommu_debug_metadata), + .need = need_iommu_debug, +}; + +static int __init iommu_debug_pagealloc(char *str) +{ + return kstrtobool(str, &needed); +} +early_param("iommu.debug_pagealloc", iommu_debug_pagealloc); diff --git a/include/linux/iommu-debug-pagealloc.h b/include/linux/iommu-debug-pagealloc.h new file mode 100644 index 000000000000..83e64d70bf6c --- /dev/null +++ b/include/linux/iommu-debug-pagealloc.h @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 - Google Inc + * Author: Mostafa Saleh + * IOMMU API debug page alloc sanitizer + */ + +#ifndef __LINUX_IOMMU_DEBUG_PAGEALLOC_H +#define __LINUX_IOMMU_DEBUG_PAGEALLOC_H + +#ifdef CONFIG_IOMMU_DEBUG_PAGEALLOC + +extern struct page_ext_operations page_iommu_debug_ops; + +#endif /* CONFIG_IOMMU_DEBUG_PAGEALLOC */ + +#endif /* __LINUX_IOMMU_DEBUG_PAGEALLOC_H */ diff --git a/mm/page_ext.c b/mm/page_ext.c index d7396a8970e5..297e4cd8ce90 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c @@ -11,6 +11,7 @@ #include #include #include +#include /* * struct page extension @@ -89,6 +90,9 @@ static struct page_ext_operations *page_ext_ops[] __initdata = { #ifdef CONFIG_PAGE_TABLE_CHECK &page_table_check_ops, #endif +#ifdef CONFIG_IOMMU_DEBUG_PAGEALLOC + &page_iommu_debug_ops, +#endif }; unsigned long page_ext_size; -- 2.52.0.223.gf5cc29aaa4-goog