From patchwork Mon Jan 9 17:47:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 13094047 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 63E81C54EBD for ; Mon, 9 Jan 2023 17:52:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6XhyYpZgMnezd2E7124lxfncOqTkW8rbotGllk3C9ZQ=; b=liupfeooTRgHKq qHm/uscLhkWkAPZXID2O4szr3qw/YwU3QQTE19NyMhxcSEdAtW5D4YG66wL+J5r0+KJK+UPnL6QXA X+efU0YkRSSRFJ+E6oZvDnFn/oYie5p/5PM8aYZwQgGHGyT6hJcI2x1w+IPCAtp1WjTulaLXop2mC Wppfbml31X+D+sdYRQvrb8rU6z2qSqJNe0WhI6Yuivnwb8iGPRJC7FdYOsLFTTOaV5UEjJb9pxJ8j Del1L6N3Gl70VnpE/PqE3yQQw/wwnuoRhxuMrfIVTaJIKPGmIJSQbEtqxQxcop1Rkc2d/zPYpGPL5 qT1p7pmJ3ih5GHCw+pUQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pEwIk-0031ho-0G; Mon, 09 Jan 2023 17:51:15 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1pEwFn-00304X-DH for linux-arm-kernel@lists.infradead.org; Mon, 09 Jan 2023 17:48:14 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D646761299; Mon, 9 Jan 2023 17:48:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B623C433D2; Mon, 9 Jan 2023 17:48:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673286490; bh=3/offehC15LZ6/BvqOb+3fbnk4F90UgfhDAUzleeXtU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YhE/JuDWg9kUepq9rqJ2F0cRA/hfZaIjFz7g6s1qHlkHnMENeIcqbgU+/b955wypZ 2ZjDHcWSuO/jfE7Qwwr8FWJ55jKWtGCvYwcZfvacOA0dmMaKx4JNz3rQz+cF+QQrUS qoGSy9J+xZkEOROkkcttLR61K5/O99i/NwmKdJyiAZSQ50I5wrgUck9iV9sSFE/PLf Kl95AOfc2oXamtG+x2DNiGyQHDkysqjvshktPGWcja455Le8BtMm1ATZwYsUPYmoDe Yzzi7tFRDAkOx2vc1u7pLB99zNLZWH0KQv2FMpS+ZwQd6j5wARhNlUBCka5Nvwf1L/ yMlhyU2ZV7Vtg== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Sami Tolvanen , Kees Cook Subject: [PATCH v2 1/2] arm64: Always load shadow stack pointer directly from the task struct Date: Mon, 9 Jan 2023 18:47:59 +0100 Message-Id: <20230109174800.3286265-2-ardb@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230109174800.3286265-1-ardb@kernel.org> References: <20230109174800.3286265-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2302; i=ardb@kernel.org; h=from:subject; bh=3/offehC15LZ6/BvqOb+3fbnk4F90UgfhDAUzleeXtU=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBjvFNOaEusriFg80EEK+K7rfPqTe+bTnBV+M3T4Ujq nybBulqJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCY7xTTgAKCRDDTyI5ktmPJLR4C/ 9NM1LnJgh+iv3KCnLT9M5ZlG3ZxYu1GcvkbFmtGDuH5zCyFP1xFj+ODLStBPVNjH2Hr7ZQMe0wLbvh N/ox/N/EFjYDyJRaU2LC2Ms1OsmDdLibPlTomVxSAw4xx8z/TpdBJDfc+8dmLqUOhKahob3e93/Prp uwxscKF5RE+3mbnoeMQ6U2uNC6RIJfIB/7uNuOlJs/j4EE1OQ0w8rtEAtmacPhU5Uo5WPPH7K3ja3P tkWVVRXLvFpYe73+3ODWYRIcxCJyvoZSYgeCvAjGXri7+4tHqgjqJ8WDUKHLzUcJKPxgnnvRY+jkO3 tGeEr3+jleezqZIXg/GaZ6cTFg7GIqJjTImH2ey+iG2jwNFr+y/vo21bIGUSB7osPXEhhXRObrty+z 1U3CztJAqDyw23SbjSrwBvn9lVp4/ROvHD4zSfgJwTOMKnOJChoUwO79n3QVumwS8sr/CxIB8esnGi fDSp1jvKqmuRxwoZBbvfnAoiZorgomnAaD7zlhG17KLDc= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230109_094812_000146_6E05F45D X-CRM114-Status: GOOD ( 12.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org All occurrences of the scs_load macro load the value of the shadow call stack pointer from the task which is current at that point. So instead of taking a task struct register argument in the scs_load macro to specify the task struct to load from, let's always reference the current task directly. This should make it much harder to exploit any instruction sequences reloading the shadow call stack pointer register from memory. Signed-off-by: Ard Biesheuvel Acked-by: Mark Rutland Reviewed-by: Kees Cook --- arch/arm64/include/asm/scs.h | 7 ++++--- arch/arm64/kernel/entry.S | 4 ++-- arch/arm64/kernel/head.S | 2 +- 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h index ff7da1268a52ab79..13df982a080805e6 100644 --- a/arch/arm64/include/asm/scs.h +++ b/arch/arm64/include/asm/scs.h @@ -10,15 +10,16 @@ #ifdef CONFIG_SHADOW_CALL_STACK scs_sp .req x18 - .macro scs_load tsk - ldr scs_sp, [\tsk, #TSK_TI_SCS_SP] + .macro scs_load_current + get_current_task scs_sp + ldr scs_sp, [scs_sp, #TSK_TI_SCS_SP] .endm .macro scs_save tsk str scs_sp, [\tsk, #TSK_TI_SCS_SP] .endm #else - .macro scs_load tsk + .macro scs_load_current .endm .macro scs_save tsk diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 11cb99c4d298784d..546f7773238ea45d 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -275,7 +275,7 @@ alternative_if ARM64_HAS_ADDRESS_AUTH alternative_else_nop_endif 1: - scs_load tsk + scs_load_current .else add x21, sp, #PT_REGS_SIZE get_current_task tsk @@ -848,7 +848,7 @@ SYM_FUNC_START(cpu_switch_to) msr sp_el0, x1 ptrauth_keys_install_kernel x1, x8, x9, x10 scs_save x0 - scs_load x1 + scs_load_current ret SYM_FUNC_END(cpu_switch_to) NOKPROBE(cpu_switch_to) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 952e17bd1c0b4f91..b9c1a506798ea315 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -404,7 +404,7 @@ SYM_FUNC_END(create_kernel_mapping) stp xzr, xzr, [sp, #S_STACKFRAME] add x29, sp, #S_STACKFRAME - scs_load \tsk + scs_load_current adr_l \tmp1, __per_cpu_offset ldr w\tmp2, [\tsk, #TSK_TI_CPU]