linux-kernel - [PATCH v10 17/27] powerpc: check key protection for user page access

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Message-Id: <1516326648-22775-18-git-send-email-linuxram@us.ibm.com>
Date:   Thu, 18 Jan 2018 17:50:38 -0800
From:   Ram Pai <linuxram@...ibm.com>
To:     mpe@...erman.id.au, mingo@...hat.com, akpm@...ux-foundation.org,
        corbet@....net, arnd@...db.de
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org, x86@...nel.org,
        linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, benh@...nel.crashing.org, paulus@...ba.org,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, hbabu@...ibm.com, mhocko@...nel.org,
        bauerman@...ux.vnet.ibm.com, ebiederm@...ssion.com,
        linuxram@...ibm.com
Subject: [PATCH v10 17/27] powerpc: check key protection for user page access

Make sure that the kernel does not access user pages without
checking their key-protection.

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index e785c68..3d8186e 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -464,6 +464,25 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 
 #ifdef CONFIG_PPC_MEM_KEYS
 extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute);
+
+#define pte_access_permitted(pte, write) \
+	(pte_present(pte) && \
+	 ((!(write) || pte_write(pte)) && \
+	  arch_pte_access_permitted(pte_val(pte), !!write, 0)))
+
+/*
+ * We store key in pmd/pud for huge pages. Need to check for key protection.
+ */
+#define pmd_access_permitted(pmd, write) \
+	(pmd_present(pmd) && \
+	 ((!(write) || pmd_write(pmd)) && \
+	  arch_pte_access_permitted(pmd_val(pmd), !!write, 0)))
+
+#define pud_access_permitted(pud, write) \
+	(pud_present(pud) && \
+	 ((!(write) || pud_write(pud)) && \
+	  arch_pte_access_permitted(pud_val(pud), !!write, 0)))
+
 #endif /* CONFIG_PPC_MEM_KEYS */
 
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
-- 
1.7.1