linux-kernel - [RFC v6 30/62] powerpc: implementation for arch_vma_access

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1500177424-13695-31-git-send-email-linuxram@us.ibm.com>
Date:   Sat, 15 Jul 2017 20:56:32 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, dave.hansen@...el.com, hbabu@...ibm.com,
        linuxram@...ibm.com, arnd@...db.de, akpm@...ux-foundation.org,
        corbet@....net, mingo@...hat.com, mhocko@...nel.org
Subject: [RFC v6 30/62] powerpc: implementation for arch_vma_access_permitted()

This patch provides the implementation for
arch_vma_access_permitted(). Returns true if the
requested access is allowed by pkey associated with the
vma.

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 arch/powerpc/include/asm/mmu_context.h |    5 +++-
 arch/powerpc/mm/pkeys.c                |   43 ++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 7232484..635d4a6 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -175,6 +175,10 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
 {
 }
 
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+bool arch_vma_access_permitted(struct vm_area_struct *vma,
+			bool write, bool execute, bool foreign);
+#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 		bool write, bool execute, bool foreign)
 {
@@ -182,7 +186,6 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 	return true;
 }
 
-#ifndef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
 #define pkey_initialize()
 #define pkey_mm_init(mm)
 
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 1794e17..9999ce1 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -234,3 +234,46 @@ bool arch_pte_access_permitted(u64 pte, bool write, bool execute)
 	return pkey_access_permitted(pte_to_pkey_bits(pte),
 			write, execute);
 }
+
+/*
+ * We only want to enforce protection keys on the current process
+ * because we effectively have no access to AMR/IAMR for other
+ * processes or any way to tell *which * AMR/IAMR in a threaded
+ * process we could use.
+ *
+ * So do not enforce things if the VMA is not from the current
+ * mm, or if we are in a kernel thread.
+ */
+static inline bool vma_is_foreign(struct vm_area_struct *vma)
+{
+	if (!current->mm)
+		return true;
+	/*
+	 * if the VMA is from another process, then AMR/IAMR has no
+	 * relevance and should not be enforced.
+	 */
+	if (current->mm != vma->vm_mm)
+		return true;
+
+	return false;
+}
+
+bool arch_vma_access_permitted(struct vm_area_struct *vma,
+		bool write, bool execute, bool foreign)
+{
+	int pkey;
+
+	if (!pkey_inited)
+		return true;
+
+	/* allow access if the VMA is not one from this process */
+	if (foreign || vma_is_foreign(vma))
+		return true;
+
+	pkey = vma_pkey(vma);
+
+	if (!pkey)
+		return true;
+
+	return pkey_access_permitted(pkey, write, execute);
+}
-- 
1.7.1