2018-01-15 14:26:15 +03:00
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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2018-01-06 17:13:39 +03:00
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From: Andy Lutomirski <luto@kernel.org>
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Date: Mon, 4 Dec 2017 15:07:45 +0100
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2018-01-15 14:26:15 +03:00
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Subject: [PATCH] x86/mm/pti: Share cpu_entry_area with user space page tables
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2018-01-06 17:13:39 +03:00
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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Share the cpu entry area so the user space and kernel space page tables
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have the same P4D page.
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Signed-off-by: Andy Lutomirski <luto@kernel.org>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: Brian Gerst <brgerst@gmail.com>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>
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Cc: David Laight <David.Laight@aculab.com>
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Cc: Denys Vlasenko <dvlasenk@redhat.com>
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Cc: Eduardo Valentin <eduval@amazon.com>
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Cc: Greg KH <gregkh@linuxfoundation.org>
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Josh Poimboeuf <jpoimboe@redhat.com>
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Cc: Juergen Gross <jgross@suse.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Will Deacon <will.deacon@arm.com>
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Cc: aliguori@amazon.com
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Cc: daniel.gruss@iaik.tugraz.at
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Cc: hughd@google.com
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Cc: keescook@google.com
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit f7cfbee91559ca7e3e961a00ffac921208a115ad)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 6e8142de3a6e84a82a421b66a74ba37976912282)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/mm/pti.c | 25 +++++++++++++++++++++++++
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1 file changed, 25 insertions(+)
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diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
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index d58bcee470fc..59290356f19f 100644
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--- a/arch/x86/mm/pti.c
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+++ b/arch/x86/mm/pti.c
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@@ -264,6 +264,29 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
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}
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}
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+/*
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+ * Clone a single p4d (i.e. a top-level entry on 4-level systems and a
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+ * next-level entry on 5-level systems.
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+ */
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+static void __init pti_clone_p4d(unsigned long addr)
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+{
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+ p4d_t *kernel_p4d, *user_p4d;
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+ pgd_t *kernel_pgd;
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+
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+ user_p4d = pti_user_pagetable_walk_p4d(addr);
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+ kernel_pgd = pgd_offset_k(addr);
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+ kernel_p4d = p4d_offset(kernel_pgd, addr);
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+ *user_p4d = *kernel_p4d;
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+}
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+
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+/*
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+ * Clone the CPU_ENTRY_AREA into the user space visible page table.
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+ */
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+static void __init pti_clone_user_shared(void)
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+{
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+ pti_clone_p4d(CPU_ENTRY_AREA_BASE);
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+}
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+
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/*
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* Initialize kernel page table isolation
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*/
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@@ -273,4 +296,6 @@ void __init pti_init(void)
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return;
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pr_info("enabled\n");
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+
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+ pti_clone_user_shared();
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}
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--
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2.14.2
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