From mboxrd@z Thu Jan 1 00:00:00 1970 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 EC378C19F2A for ; Mon, 8 Aug 2022 01:33:12 +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=4UUh//h049R1ckXVPrixatWhYp3GswwWLfGX7mjMCXM=; b=QmgAwWXv7wxOXk JFvGvziqndpnxclxp00CPsY0QtJAj/ztKiuHx5sXCTm5hJLOGIGdq7UrefOJ/HcnNkgRfePxtVEWV bHfz6lM929vpxiBXJyN+ubQZKh0oiH7z8ctVHkNYp+Ir8n8S05p5ZLF5HMHqfAD/LNzOeWPnmX3Pz 14VSfhFyYdS9hJgGC82TCC1xDW4w3cK1iFFKLDznCUbP8+qA3ZDxChFonVaA29cQgO4W2mHKNWpPe kqbWsEMXBCFsmUpkVpmTIkj2fSDloyShSLTXBizo+KGrK/VoNQLsfJ0mdVifi9RpxFkUVoc/3bZ43 X61i9Soi2ACrnAZEEq5Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oKrck-007bS3-ER; Mon, 08 Aug 2022 01:32:06 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oKrcY-007bOC-11 for linux-arm-kernel@lists.infradead.org; Mon, 08 Aug 2022 01:31:55 +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 7E4C660DB9; Mon, 8 Aug 2022 01:31:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F862C433D7; Mon, 8 Aug 2022 01:31:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659922312; bh=M8tgTeIXH/X67VpqjvwYuPRwGg0JWAjfCSGH3QwPtlw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Noa0M+CXTD0z3HCKkY58T+GPZUkyZ+0oQT9PxI0E4zlrl7weS+aXNcBO6sFtulMBt koVql3CakU4GSUsgS+NfUZayeX8FvtMXJbgCA6VkpFasiL5vWLjqJwZjxaBf4VyX7J XjUBWNco2yOT+gMMMsUVtTwyhS1P7qqlMoCq5e1uB2+UkJu7mJKJWHtV7fP4LOr7Ob 8lO9OjA5GvBS0Xfars3HvEN7uHgH8SA2PPtvatJu0fRRDefNrRwjdoAMKvIs5hCyEm VRJsmEjn0UISbCSq1wC9jdNhsyl2QAfObYIH7QifnBmtsEx9RejA9sukTjkqn4or7B G5F8Sx+50ewkg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ard Biesheuvel , Will Deacon , Sasha Levin , catalin.marinas@arm.com, bp@suse.de, mpe@ellerman.id.au, mark.rutland@arm.com, Jason@zx2c4.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 5.19 07/58] arm64: kaslr: defer initialization to initcall where permitted Date: Sun, 7 Aug 2022 21:30:25 -0400 Message-Id: <20220808013118.313965-7-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220808013118.313965-1-sashal@kernel.org> References: <20220808013118.313965-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220807_183154_221425_D060637E X-CRM114-Status: GOOD ( 22.93 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Ard Biesheuvel [ Upstream commit fc5a89f75d2aad3e566e030675ac420aee49729c ] The early KASLR init code runs extremely early, and anything that could be deferred until later should be. So let's defer the randomization of the module region until much later - this also simplifies the arithmetic, given that we no longer have to reason about the link time vs load time placement of the core kernel explicitly. Also get rid of the global status variable, and infer the status reported by the diagnostic print from other KASLR related context. While at it, get rid of the special case for KASAN without KASAN_VMALLOC, which never occurs in practice. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20220624150651.1358849-20-ardb@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/kaslr.c | 95 +++++++++++++++++---------------------- 1 file changed, 40 insertions(+), 55 deletions(-) diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c index d5542666182f..3edee81d8ea7 100644 --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -20,14 +20,6 @@ #include #include -enum kaslr_status { - KASLR_ENABLED, - KASLR_DISABLED_CMDLINE, - KASLR_DISABLED_NO_SEED, - KASLR_DISABLED_FDT_REMAP, -}; - -static enum kaslr_status __initdata kaslr_status; u64 __ro_after_init module_alloc_base; u16 __initdata memstart_offset_seed; @@ -63,15 +55,9 @@ struct arm64_ftr_override kaslr_feature_override __initdata; u64 __init kaslr_early_init(void) { void *fdt; - u64 seed, offset, mask, module_range; + u64 seed, offset, mask; unsigned long raw; - /* - * Set a reasonable default for module_alloc_base in case - * we end up running with module randomization disabled. - */ - module_alloc_base = (u64)_etext - MODULES_VSIZE; - /* * Try to map the FDT early. If this fails, we simply bail, * and proceed with KASLR disabled. We will make another @@ -79,7 +65,6 @@ u64 __init kaslr_early_init(void) */ fdt = get_early_fdt_ptr(); if (!fdt) { - kaslr_status = KASLR_DISABLED_FDT_REMAP; return 0; } @@ -93,7 +78,6 @@ u64 __init kaslr_early_init(void) * return 0 if that is the case. */ if (kaslr_feature_override.val & kaslr_feature_override.mask & 0xf) { - kaslr_status = KASLR_DISABLED_CMDLINE; return 0; } @@ -106,7 +90,6 @@ u64 __init kaslr_early_init(void) seed ^= raw; if (!seed) { - kaslr_status = KASLR_DISABLED_NO_SEED; return 0; } @@ -126,19 +109,43 @@ u64 __init kaslr_early_init(void) /* use the top 16 bits to randomize the linear region */ memstart_offset_seed = seed >> 48; - if (!IS_ENABLED(CONFIG_KASAN_VMALLOC) && - (IS_ENABLED(CONFIG_KASAN_GENERIC) || - IS_ENABLED(CONFIG_KASAN_SW_TAGS))) - /* - * KASAN without KASAN_VMALLOC does not expect the module region - * to intersect the vmalloc region, since shadow memory is - * allocated for each module at load time, whereas the vmalloc - * region is shadowed by KASAN zero pages. So keep modules - * out of the vmalloc region if KASAN is enabled without - * KASAN_VMALLOC, and put the kernel well within 4 GB of the - * module region. - */ - return offset % SZ_2G; + return offset; +} + +static int __init kaslr_init(void) +{ + u64 module_range; + u32 seed; + + /* + * Set a reasonable default for module_alloc_base in case + * we end up running with module randomization disabled. + */ + module_alloc_base = (u64)_etext - MODULES_VSIZE; + + if (kaslr_feature_override.val & kaslr_feature_override.mask & 0xf) { + pr_info("KASLR disabled on command line\n"); + return 0; + } + + if (!kaslr_offset()) { + pr_warn("KASLR disabled due to lack of seed\n"); + return 0; + } + + pr_info("KASLR enabled\n"); + + /* + * KASAN without KASAN_VMALLOC does not expect the module region to + * intersect the vmalloc region, since shadow memory is allocated for + * each module at load time, whereas the vmalloc region will already be + * shadowed by KASAN zero pages. + */ + BUILD_BUG_ON((IS_ENABLED(CONFIG_KASAN_GENERIC) || + IS_ENABLED(CONFIG_KASAN_SW_TAGS)) && + !IS_ENABLED(CONFIG_KASAN_VMALLOC)); + + seed = get_random_u32(); if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) { /* @@ -150,8 +157,7 @@ u64 __init kaslr_early_init(void) * resolved normally.) */ module_range = SZ_2G - (u64)(_end - _stext); - module_alloc_base = max((u64)_end + offset - SZ_2G, - (u64)MODULES_VADDR); + module_alloc_base = max((u64)_end - SZ_2G, (u64)MODULES_VADDR); } else { /* * Randomize the module region by setting module_alloc_base to @@ -163,33 +169,12 @@ u64 __init kaslr_early_init(void) * when ARM64_MODULE_PLTS is enabled. */ module_range = MODULES_VSIZE - (u64)(_etext - _stext); - module_alloc_base = (u64)_etext + offset - MODULES_VSIZE; } /* use the lower 21 bits to randomize the base of the module region */ module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21; module_alloc_base &= PAGE_MASK; - return offset; -} - -static int __init kaslr_init(void) -{ - switch (kaslr_status) { - case KASLR_ENABLED: - pr_info("KASLR enabled\n"); - break; - case KASLR_DISABLED_CMDLINE: - pr_info("KASLR disabled on command line\n"); - break; - case KASLR_DISABLED_NO_SEED: - pr_warn("KASLR disabled due to lack of seed\n"); - break; - case KASLR_DISABLED_FDT_REMAP: - pr_warn("KASLR disabled due to FDT remapping failure\n"); - break; - } - return 0; } -core_initcall(kaslr_init) +subsys_initcall(kaslr_init) -- 2.35.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel