From: Ram Pai <linuxram@us.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
linux-doc@vger.kernel.org, linux-kselftest@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, arnd@arndb.de, akpm@linux-foundation.org,
corbet@lwn.net, mingo@redhat.com
Subject: [RFC v3 17/23] powerpc: Handle exceptions caused by violation of pkey protection
Date: Wed, 21 Jun 2017 18:39:33 -0700 [thread overview]
Message-ID: <1498095579-6790-18-git-send-email-linuxram@us.ibm.com> (raw)
In-Reply-To: <1498095579-6790-1-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>
---
arch/powerpc/include/asm/mmu_context.h | 12 +++++
arch/powerpc/include/asm/pkeys.h | 9 ++++
arch/powerpc/include/asm/reg.h | 2 +-
arch/powerpc/mm/fault.c | 20 ++++++++
arch/powerpc/mm/pkeys.c | 90 ++++++++++++++++++++++++++++++++++
5 files changed, 132 insertions(+), 1 deletion(-)
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 af3882f..a83722e 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 ba110dd..6e2a860 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -286,7 +286,7 @@
#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 | DSISR_BIT43)
+ 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) */
#define SPRN_CIR 0x11B /* Chip Information Register (hyper, R/0) */
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 3a7d580..3d71984 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -261,6 +261,13 @@ 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 +448,19 @@ 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,
+ is_exec, 0)) {
+ code = SEGV_PKUERR;
+ goto bad_area;
+ }
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
+ /* handle_mm_fault() needs to know if its a instruction access
+ * fault.
+ */
+ if (is_exec)
+ flags |= FAULT_FLAG_INSTRUCTION;
/*
* 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:[~2017-06-22 1:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-22 1:39 [RFC v3 00/23] powerpc: Memory Protection Keys Ram Pai
2017-06-22 1:39 ` [RFC v3 01/23] powerpc: Free up four 64K PTE bits in 4K backed HPTE pages Ram Pai
2017-06-22 9:21 ` Balbir Singh
2017-06-22 18:50 ` Ram Pai
2017-06-22 1:39 ` [RFC v3 02/23] powerpc: introduce set_hidx_slot helper Ram Pai
2017-06-25 23:03 ` Balbir Singh
2017-06-26 4:02 ` Benjamin Herrenschmidt
2017-06-27 0:17 ` Ram Pai
2017-06-27 0:16 ` Ram Pai
2017-06-22 1:39 ` [RFC v3 03/23] powerpc: introduce get_hidx_gslot helper Ram Pai
2017-06-22 1:39 ` [RFC v3 04/23] powerpc: Free up four 64K PTE bits in 64K backed HPTE pages Ram Pai
2017-06-22 1:39 ` [RFC v3 05/23] powerpc: capture the PTE format changes in the dump pte report Ram Pai
2017-06-22 1:39 ` [RFC v3 06/23] powerpc: use helper functions in __hash_page_4K() for 64K PTE Ram Pai
2017-06-22 1:39 ` [RFC v3 07/23] powerpc: use helper functions in __hash_page_4K() for 4K PTE Ram Pai
2017-06-22 1:39 ` [RFC v3 08/23] powerpc: use helper functions in flush_hash_page() Ram Pai
2017-06-22 1:39 ` [RFC v3 09/23] mm: introduce an additional vma bit for powerpc pkey Ram Pai
2017-06-22 1:39 ` [RFC v3 10/23] mm: provide the ability to disable execute on a key at creation Ram Pai
2017-06-22 1:39 ` [RFC v3 11/23] x86: key creation with PKEY_DISABLE_EXECUTE is disallowed Ram Pai
2017-06-22 1:39 ` [RFC v3 12/23] powerpc: Implement sys_pkey_alloc and sys_pkey_free system call Ram Pai
2017-06-22 1:39 ` [RFC v3 13/23] powerpc: store and restore the pkey state across context switches Ram Pai
2017-06-22 1:39 ` [RFC v3 14/23] powerpc: Implementation for sys_mprotect_pkey() system call Ram Pai
2017-06-22 1:39 ` [RFC v3 15/23] powerpc: Program HPTE key protection bits Ram Pai
2017-06-22 1:39 ` [RFC v3 16/23] powerpc: Macro the mask used for checking DSI exception Ram Pai
2017-06-22 1:39 ` Ram Pai [this message]
2017-06-22 1:39 ` [RFC v3 18/23] powerpc: Deliver SEGV signal on pkey violation Ram Pai
2017-06-22 1:39 ` [RFC v3 19/23] selftest: Move protecton key selftest to arch neutral directory Ram Pai
2017-06-22 1:39 ` [RFC v3 20/23] selftest: PowerPC specific test updates to memory protection keys Ram Pai
2017-06-22 1:39 ` [RFC v3 21/23] Documentation: Move protecton key documentation to arch neutral directory Ram Pai
2017-06-22 1:39 ` [RFC v3 22/23] Documentation: PowerPC specific updates to memory protection keys Ram Pai
2017-06-22 1:39 ` [RFC v3 23/23] procfs: display the protection-key number associated with a vma Ram Pai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1498095579-6790-18-git-send-email-linuxram@us.ibm.com \
--to=linuxram@us.ibm.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=arnd@arndb.de \
--cc=benh@kernel.crashing.org \
--cc=bsingharora@gmail.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@intel.com \
--cc=hbabu@us.ibm.com \
--cc=khandual@linux.vnet.ibm.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mingo@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).