From: Ram Pai <linuxram@us.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com,
bsingharora@gmail.com, dave.hansen@intel.com, hbabu@us.ibm.com,
linuxram@us.ibm.com
Subject: [RFC v2 08/12] powerpc: Handle exceptions caused by violation of pkey protection.
Date: Fri, 16 Jun 2017 20:52:40 -0700 [thread overview]
Message-ID: <1497671564-20030-9-git-send-email-linuxram@us.ibm.com> (raw)
In-Reply-To: <1497671564-20030-1-git-send-email-linuxram@us.ibm.com>
Handle Data and Instruction exceptions caused by memory
protection-key.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
(cherry picked from commit a5e5217619a0c475fe0cacc3b0cf1d3d33c79a09)
Conflicts:
arch/powerpc/include/asm/reg.h
arch/powerpc/kernel/exceptions-64s.S
---
arch/powerpc/include/asm/mmu_context.h | 12 +++++
arch/powerpc/include/asm/pkeys.h | 9 ++++
arch/powerpc/include/asm/reg.h | 7 +--
arch/powerpc/mm/fault.c | 21 +++++++-
arch/powerpc/mm/pkeys.c | 90 ++++++++++++++++++++++++++++++++++
5 files changed, 134 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index da7e943..71fffe0 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -175,11 +175,23 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
{
}
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+bool arch_pte_access_permitted(pte_t pte, bool write);
+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_pte_access_permitted(pte_t pte, bool write)
+{
+ /* by default, allow everything */
+ return true;
+}
static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
bool write, bool execute, bool foreign)
{
/* by default, allow everything */
return true;
}
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
#endif /* __KERNEL__ */
#endif /* __ASM_POWERPC_MMU_CONTEXT_H */
diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 9b6820d..405e7db 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -14,6 +14,15 @@
VM_PKEY_BIT3 | \
VM_PKEY_BIT4)
+static inline u16 pte_flags_to_pkey(unsigned long pte_flags)
+{
+ return ((pte_flags & H_PAGE_PKEY_BIT4) ? 0x1 : 0x0) |
+ ((pte_flags & H_PAGE_PKEY_BIT3) ? 0x2 : 0x0) |
+ ((pte_flags & H_PAGE_PKEY_BIT2) ? 0x4 : 0x0) |
+ ((pte_flags & H_PAGE_PKEY_BIT1) ? 0x8 : 0x0) |
+ ((pte_flags & H_PAGE_PKEY_BIT0) ? 0x10 : 0x0);
+}
+
#define pkey_to_vmflag_bits(key) (((key & 0x1UL) ? VM_PKEY_BIT0 : 0x0UL) | \
((key & 0x2UL) ? VM_PKEY_BIT1 : 0x0UL) | \
((key & 0x4UL) ? VM_PKEY_BIT2 : 0x0UL) | \
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 2dcb8a1..a11977f 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -285,9 +285,10 @@
#define DSISR_UNSUPP_MMU 0x00080000 /* Unsupported MMU config */
#define DSISR_SET_RC 0x00040000 /* Failed setting of R/C bits */
#define DSISR_PGDIRFAULT 0x00020000 /* Fault on page directory */
-#define DSISR_PAGE_FAULT_MASK (DSISR_BIT32 | \
- DSISR_PAGEATTR_CONFLT | \
- DSISR_BADACCESS | \
+#define DSISR_PAGE_FAULT_MASK (DSISR_BIT32 | \
+ DSISR_PAGEATTR_CONFLT | \
+ DSISR_BADACCESS | \
+ DSISR_KEYFAULT | \
DSISR_BIT43)
#define SPRN_TBRL 0x10C /* Time Base Read Lower Register (user, R/O) */
#define SPRN_TBRU 0x10D /* Time Base Read Upper Register (user, R/O) */
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 3a7d580..c31624f 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -216,9 +216,10 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
* bits we are interested in. But there are some bits which
* indicate errors in DSISR but can validly be set in SRR1.
*/
- if (trap == 0x400)
+ if (trap == 0x400) {
error_code &= 0x48200000;
- else
+ flags |= FAULT_FLAG_INSTRUCTION;
+ } else
is_write = error_code & DSISR_ISSTORE;
#else
is_write = error_code & ESR_DST;
@@ -261,6 +262,13 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
}
#endif
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+ if (error_code & DSISR_KEYFAULT) {
+ code = SEGV_PKUERR;
+ goto bad_area_nosemaphore;
+ }
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
@@ -441,6 +449,15 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
#endif /* CONFIG_PPC_STD_MMU */
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+ if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
+ flags & FAULT_FLAG_INSTRUCTION,
+ 0)) {
+ code = SEGV_PKUERR;
+ goto bad_area;
+ }
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 11a32b3..439241a 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -27,6 +27,37 @@ static inline bool pkey_allows_readwrite(int pkey)
return !(read_amr() & ((AMR_AD_BIT|AMR_WD_BIT) << pkey_shift));
}
+static inline bool pkey_allows_read(int pkey)
+{
+ int pkey_shift = (arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY;
+
+ if (!(read_uamor() & (0x3ul << pkey_shift)))
+ return true;
+
+ return !(read_amr() & (AMR_AD_BIT << pkey_shift));
+}
+
+static inline bool pkey_allows_write(int pkey)
+{
+ int pkey_shift = (arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY;
+
+ if (!(read_uamor() & (0x3ul << pkey_shift)))
+ return true;
+
+ return !(read_amr() & (AMR_WD_BIT << pkey_shift));
+}
+
+static inline bool pkey_allows_execute(int pkey)
+{
+ int pkey_shift = (arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY;
+
+ if (!(read_uamor() & (0x3ul << pkey_shift)))
+ return true;
+
+ return !(read_iamr() & (IAMR_EX_BIT << pkey_shift));
+}
+
+
/*
* set the access right in AMR IAMR and UAMOR register
* for @pkey to that specified in @init_val.
@@ -175,3 +206,62 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot,
*/
return vma_pkey(vma);
}
+
+bool arch_pte_access_permitted(pte_t pte, bool write)
+{
+ int pkey = pte_flags_to_pkey(pte_val(pte));
+
+ if (!pkey_allows_read(pkey))
+ return false;
+ if (write && !pkey_allows_write(pkey))
+ return false;
+ return true;
+}
+
+/*
+ * 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;
+ /* 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;
+
+ if (execute)
+ return pkey_allows_execute(pkey);
+
+ if (!pkey_allows_read(pkey))
+ return false;
+
+ if (write)
+ return pkey_allows_write(pkey);
+
+ return true;
+}
--
1.8.3.1
next prev parent reply other threads:[~2017-06-17 3:53 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-17 3:52 [RFC v2 00/12] powerpc: Memory Protection Keys Ram Pai
2017-06-17 3:52 ` [RFC v2 01/12] powerpc: Free up four 64K PTE bits in 4K backed hpte pages Ram Pai
2017-06-20 10:20 ` Anshuman Khandual
2017-06-20 23:23 ` Ram Pai
2017-06-21 5:35 ` Anshuman Khandual
2017-06-21 6:34 ` Ram Pai
2017-06-21 6:41 ` Aneesh Kumar K.V
2017-06-21 9:30 ` Ram Pai
2017-06-22 9:07 ` Anshuman Khandual
2017-06-22 16:20 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 02/12] powerpc: Free up four 64K PTE bits in 64K " Ram Pai
2017-06-20 10:51 ` Anshuman Khandual
2017-06-20 23:25 ` Ram Pai
2017-06-21 6:50 ` Aneesh Kumar K.V
2017-06-21 6:54 ` Aneesh Kumar K.V
2017-06-21 20:14 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 03/12] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call Ram Pai
2017-06-19 12:18 ` Michael Ellerman
2017-06-20 22:45 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 04/12] powerpc: store and restore the pkey state across context switches Ram Pai
2017-06-17 3:52 ` [RFC v2 05/12] powerpc: Implementation for sys_mprotect_pkey() system call Ram Pai
2017-06-21 7:16 ` Aneesh Kumar K.V
2017-06-17 3:52 ` [RFC v2 06/12] powerpc: Program HPTE key protection bits Ram Pai
2017-06-20 8:21 ` Anshuman Khandual
2017-06-20 23:26 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 07/12] powerpc: Macro the mask used for checking DSI exception Ram Pai
2017-06-20 8:14 ` Anshuman Khandual
2017-06-20 23:28 ` Ram Pai
2017-06-21 7:25 ` Aneesh Kumar K.V
2017-06-21 9:17 ` Ram Pai
2017-06-17 3:52 ` Ram Pai [this message]
2017-06-20 7:24 ` [RFC v2 08/12] powerpc: Handle exceptions caused by violation of pkey protection Anshuman Khandual
2017-06-20 23:43 ` Ram Pai
2017-06-21 3:54 ` Anshuman Khandual
2017-06-21 6:26 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 09/12] powerpc: Deliver SEGV signal on pkey violation Ram Pai
2017-06-20 6:54 ` Anshuman Khandual
2017-06-20 23:56 ` Ram Pai
2017-06-21 3:18 ` Anshuman Khandual
2017-06-21 6:10 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 10/12] powerpc: Read AMR only if pkey-violation caused the exception Ram Pai
2017-06-19 11:06 ` Michael Ellerman
2017-06-19 17:59 ` Ram Pai
2017-06-20 6:46 ` Anshuman Khandual
2017-06-20 23:58 ` Ram Pai
2017-06-20 23:56 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 11/12]Documentation: Documentation updates Ram Pai
2017-06-20 6:18 ` Anshuman Khandual
2017-06-21 0:04 ` Ram Pai
2017-06-17 3:52 ` [RFC v2 12/12]selftest: Updated protection key selftest Ram Pai
2017-06-19 11:04 ` Michael Ellerman
2017-06-20 6:26 ` Anshuman Khandual
2017-06-21 0:10 ` Ram Pai
2017-06-20 5:10 ` [RFC v2 00/12] powerpc: Memory Protection Keys Balbir Singh
2017-06-20 6:05 ` Anshuman Khandual
2017-06-20 9:56 ` Benjamin Herrenschmidt
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