From patchwork Fri Aug 11 03:37:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Lynch via B4 Relay X-Patchwork-Id: 13350046 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 67CFFC001E0 for ; Fri, 11 Aug 2023 03:38:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229757AbjHKDiM (ORCPT ); Thu, 10 Aug 2023 23:38:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229457AbjHKDiL (ORCPT ); Thu, 10 Aug 2023 23:38:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C0CB26A0; Thu, 10 Aug 2023 20:38:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2A27264CCF; Fri, 11 Aug 2023 03:38:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPS id 7CEFBC433C8; Fri, 11 Aug 2023 03:38:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691725090; bh=whhV6SkWkfSGuUqgawwieXdrPYWPSac+Odl5OgaklPE=; h=From:Date:Subject:To:Cc:Reply-To:From; b=DfDe0sLPiPncLsY2sbT70pZ0lDY1i41wPQVm/fwKmZ0U2fNXlG1fYIH+4AZj0qyln 1dEdQED/NP4pGRVef+jrI0UlYHKsadZJp4B+x4CfsOij5dIxYwUyJ7hsVc4jaZiY25 PbqaAHcl3uT5ijrOe23XaoQWLNAZ96dKrLtGov+j/5fGVGzTDZnbl2sXmNlUOydmB7 y+dwA1ogfv2uWJeP1o1C3UVnKxkaPur7KLMIr/hsssimMSvO5RbVoZsnA4qORKybg5 Wi7ItzfogLeAeqR3b+rMvtAusPlURfYicquZZUMfqmpzfbO8S7GgkrzclopjGPtExT 6CvvPCun/7zzg== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 603D9C001DE; Fri, 11 Aug 2023 03:38:10 +0000 (UTC) From: Nathan Lynch via B4 Relay Date: Thu, 10 Aug 2023 22:37:55 -0500 Subject: [PATCH v2] powerpc/rtas_flash: allow user copy to flash block cache objects MIME-Version: 1.0 Message-Id: <20230810-rtas-flash-vs-hardened-usercopy-v2-1-dcf63793a938@linux.ibm.com> X-B4-Tracking: v=1; b=H4sIABKt1WQC/4XNQQ6DIBCF4asY1h0DmNjSVe/RuEAYyyQKDSjRG O9eag/Q5f8W39tZwkiY2L3aWcRMiYIvIS8VM077FwLZ0kxy2fBrIyDOOsEw6uQgJ3A6WvRoYSm OCe8NuNKtlU3bcyFYUd4RB1rPh2dX2lGaQ9zOwyy+68++8f92FiBAolJmUCh7tI+R/LLW1E+1C RPrjuP4AOBsLJnSAAAA To: Michael Ellerman , Nicholas Piggin , Christophe Leroy , Kees Cook Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Nathan Lynch X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1691725089; l=3245; i=nathanl@linux.ibm.com; s=20230206; h=from:subject:message-id; bh=mnxTyBgPfZp2EwTmjYzNjMI5jJcJ4qTWUk5dzWOmYlA=; b=x0ZNdmr3h+oB6GmQqV4qkH5z0Kn3pjHXJhNWw+wl5tKyWa6HZJ6Ppd1jwAMLXktRgXVkRrfzu MIoMmqKBswLBh9MUxfzfOgjHQJZkouOSveeH8oS+DXgkIHSpwdAynpi X-Developer-Key: i=nathanl@linux.ibm.com; a=ed25519; pk=6daubz/ymoaMF+8voz7UHwnhluEsmDZuqygIIMWpQQY= X-Endpoint-Received: by B4 Relay for nathanl@linux.ibm.com/20230206 with auth_id=27 X-Original-From: Nathan Lynch Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org From: Nathan Lynch With hardened usercopy enabled (CONFIG_HARDENED_USERCOPY=y), using the /proc/powerpc/rtas/firmware_update interface to prepare a system firmware update yields a BUG(): kernel BUG at mm/usercopy.c:102! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: CPU: 0 PID: 2232 Comm: dd Not tainted 6.5.0-rc3+ #2 Hardware name: IBM,8408-E8E POWER8E (raw) 0x4b0201 0xf000004 of:IBM,FW860.50 (SV860_146) hv:phyp pSeries NIP: c0000000005991d0 LR: c0000000005991cc CTR: 0000000000000000 REGS: c0000000148c76a0 TRAP: 0700 Not tainted (6.5.0-rc3+) MSR: 8000000000029033 CR: 24002242 XER: 0000000c CFAR: c0000000001fbd34 IRQMASK: 0 [ ... GPRs omitted ... ] NIP [c0000000005991d0] usercopy_abort+0xa0/0xb0 LR [c0000000005991cc] usercopy_abort+0x9c/0xb0 Call Trace: [c0000000148c7940] [c0000000005991cc] usercopy_abort+0x9c/0xb0 (unreliable) [c0000000148c79b0] [c000000000536814] __check_heap_object+0x1b4/0x1d0 [c0000000148c79f0] [c000000000599080] __check_object_size+0x2d0/0x380 [c0000000148c7a30] [c000000000045ed4] rtas_flash_write+0xe4/0x250 [c0000000148c7a80] [c00000000068a0fc] proc_reg_write+0xfc/0x160 [c0000000148c7ab0] [c0000000005a381c] vfs_write+0xfc/0x4e0 [c0000000148c7b70] [c0000000005a3e10] ksys_write+0x90/0x160 [c0000000148c7bc0] [c00000000002f2c8] system_call_exception+0x178/0x320 [c0000000148c7e50] [c00000000000d520] system_call_common+0x160/0x2c4 --- interrupt: c00 at 0x7fff9f17e5e4 The blocks of the firmware image are copied directly from user memory to objects allocated from flash_block_cache, so flash_block_cache must be created using kmem_cache_create_usercopy() to mark it safe for user access. Fixes: 6d07d1cd300f ("usercopy: Restrict non-usercopy caches to size 0") Signed-off-by: Nathan Lynch Reviewed-by: Kees Cook --- I believe it's much more common to update Power system firmware without involving a Linux partition, which may explain why this has gone unreported for so long. --- Changes in v2: - Drop excessive local const variables. No functional change. - Link to v1: https://lore.kernel.org/r/20230801-rtas-flash-vs-hardened-usercopy-v1-1-2e99cf9e2bed@linux.ibm.com --- arch/powerpc/kernel/rtas_flash.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- base-commit: c3cad890877f59aeeaf5a638aa7a7c0612c16fa1 change-id: 20230731-rtas-flash-vs-hardened-usercopy-09a6d236b011 Best regards, diff --git a/arch/powerpc/kernel/rtas_flash.c b/arch/powerpc/kernel/rtas_flash.c index 4caf5e3079eb..359577ec1680 100644 --- a/arch/powerpc/kernel/rtas_flash.c +++ b/arch/powerpc/kernel/rtas_flash.c @@ -709,9 +709,9 @@ static int __init rtas_flash_init(void) if (!rtas_validate_flash_data.buf) return -ENOMEM; - flash_block_cache = kmem_cache_create("rtas_flash_cache", - RTAS_BLK_SIZE, RTAS_BLK_SIZE, 0, - NULL); + flash_block_cache = kmem_cache_create_usercopy("rtas_flash_cache", + RTAS_BLK_SIZE, RTAS_BLK_SIZE, + 0, 0, RTAS_BLK_SIZE, NULL); if (!flash_block_cache) { printk(KERN_ERR "%s: failed to create block cache\n", __func__);