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 AD748C19F2A for ; Mon, 8 Aug 2022 02:10:16 +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=QHmrLHLZab6hPO LfB4QMPa2iSvzyPQgxVXDMEvC911nEcrckgsnCvgpS+ZQ4Kw+vbd1Q6R3E8nwv7DM0H4Z262BqvR8 ZHeVkwDvzMDXuJNY48quppZwv+U5UzypwKyxuz5Cz8fkOzGKM1q7a1rya86IqRLp+VDsdTCh3vpkw dM5pigX8ftopdxT6A7SpdeYSzijrE+LVXtrUzEc+zpDOGaHgz2wuWQhh9nBdouEdIrbTuPNyh1mmC 6tmDmxz5iz2VI9tzTDOcyTFT11qpCt4IYI+AUPO+eMwCsYRdxqxER4EwS2xSY+pj05VR9pMV0yZNP rzSIP4pir62sfdahzeNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oKsCd-007sI3-53; Mon, 08 Aug 2022 02:09:11 +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 1oKrgm-007dlU-S4 for linux-arm-kernel@lists.infradead.org; Mon, 08 Aug 2022 01:36:18 +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 2B0B860E8E; Mon, 8 Aug 2022 01:36:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 99B8EC4314C; Mon, 8 Aug 2022 01:36:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659922576; bh=M8tgTeIXH/X67VpqjvwYuPRwGg0JWAjfCSGH3QwPtlw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C4HJ53h2qeThYSz1Kvj9bKuz2BB6OD30uGDsiQhv9Ej8KutqQ9ioMndu/jguF9K0q L3Ot2MKHFEYzAhXOlqTWqQvvQX53R8jvyl20NVV2aH3SiCBp/19l6Bwjnevnp6skFq PliwsJDf6Xu2lXSPgodo/qGYuZHsRuK9bYlJRvb11EcnANAbBfbR/goDoAcAksoBFG +EyZYOyaT4CBnfmlK1xxjriARFhOT7hVv6MQNvm77bHMIObsxvcnStFMCgoP169Pas CKMgzVw00rhS29EYviS7xGaT9mEbf4agTKwPVLBPTxlodqTKD1BeDNYQmoZxcjloLY jrd5Q1FXEbarA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ard Biesheuvel , Will Deacon , Sasha Levin , catalin.marinas@arm.com, hca@linux.ibm.com, mpe@ellerman.id.au, mark.rutland@arm.com, Jason@zx2c4.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 5.15 05/45] arm64: kaslr: defer initialization to initcall where permitted Date: Sun, 7 Aug 2022 21:35:09 -0400 Message-Id: <20220808013551.315446-5-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220808013551.315446-1-sashal@kernel.org> References: <20220808013551.315446-1-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_183617_023160_BFF99A90 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