Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753036AbdF0KRT (ORCPT ); Tue, 27 Jun 2017 06:17:19 -0400 Received: from mail-qk0-f196.google.com ([209.85.220.196]:35875 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751699AbdF0KMd (ORCPT ); Tue, 27 Jun 2017 06:12:33 -0400 From: Ram Pai 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 v4 06/17] powerpc: Implementation for sys_mprotect_pkey() system call Date: Tue, 27 Jun 2017 03:11:48 -0700 Message-Id: <1498558319-32466-7-git-send-email-linuxram@us.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1498558319-32466-1-git-send-email-linuxram@us.ibm.com> References: <1498558319-32466-1-git-send-email-linuxram@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7074 Lines: 237 This system call, associates the pkey with vma corresponding to the given address range. Signed-off-by: Ram Pai --- arch/powerpc/include/asm/mman.h | 8 ++- arch/powerpc/include/asm/pkeys.h | 17 ++++++- arch/powerpc/include/asm/systbl.h | 1 + arch/powerpc/include/asm/unistd.h | 4 +- arch/powerpc/include/uapi/asm/unistd.h | 1 + arch/powerpc/mm/pkeys.c | 93 +++++++++++++++++++++++++++++++++- 6 files changed, 117 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h index 30922f6..067eec2 100644 --- a/arch/powerpc/include/asm/mman.h +++ b/arch/powerpc/include/asm/mman.h @@ -13,6 +13,7 @@ #include #include +#include #include /* @@ -22,7 +23,12 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, unsigned long pkey) { - return (prot & PROT_SAO) ? VM_SAO : 0; +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + return (((prot & PROT_SAO) ? VM_SAO : 0) | + pkey_to_vmflag_bits(pkey)); +#else + return ((prot & PROT_SAO) ? VM_SAO : 0); +#endif } #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey) diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 7bc8746..41bf5d4 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 unsigned long pkey_to_vmflag_bits(int pkey) +{ + return (((pkey & 0x1UL) ? VM_PKEY_BIT0 : 0x0UL) | + ((pkey & 0x2UL) ? VM_PKEY_BIT1 : 0x0UL) | + ((pkey & 0x4UL) ? VM_PKEY_BIT2 : 0x0UL) | + ((pkey & 0x8UL) ? VM_PKEY_BIT3 : 0x0UL) | + ((pkey & 0x10UL) ? VM_PKEY_BIT4 : 0x0UL)); +} + /* * Bits are in BE format. * NOTE: key 31, 1, 0 are not used. @@ -42,6 +51,12 @@ #define mm_set_pkey_is_reserved(mm, pkey) (PKEY_INITIAL_ALLOCAION & \ pkeybit_mask(pkey)) + +static inline int vma_pkey(struct vm_area_struct *vma) +{ + return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; +} + static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) { /* a reserved key is never considered as 'explicitly allocated' */ @@ -114,7 +129,7 @@ static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, return __arch_set_user_pkey_access(tsk, pkey, init_val); } -static inline pkey_mm_init(struct mm_struct *mm) +static inline void pkey_mm_init(struct mm_struct *mm) { mm_pkey_allocation_map(mm) = PKEY_INITIAL_ALLOCAION; /* -1 means unallocated or invalid */ diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h index 22dd776..b33b551 100644 --- a/arch/powerpc/include/asm/systbl.h +++ b/arch/powerpc/include/asm/systbl.h @@ -390,3 +390,4 @@ SYSCALL(statx) SYSCALL(pkey_alloc) SYSCALL(pkey_free) +SYSCALL(pkey_mprotect) diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h index e0273bc..daf1ba9 100644 --- a/arch/powerpc/include/asm/unistd.h +++ b/arch/powerpc/include/asm/unistd.h @@ -12,12 +12,10 @@ #include -#define NR_syscalls 386 +#define NR_syscalls 387 #define __NR__exit __NR_exit -#define __IGNORE_pkey_mprotect - #ifndef __ASSEMBLY__ #include diff --git a/arch/powerpc/include/uapi/asm/unistd.h b/arch/powerpc/include/uapi/asm/unistd.h index 7993a07..71ae45e 100644 --- a/arch/powerpc/include/uapi/asm/unistd.h +++ b/arch/powerpc/include/uapi/asm/unistd.h @@ -396,5 +396,6 @@ #define __NR_statx 383 #define __NR_pkey_alloc 384 #define __NR_pkey_free 385 +#define __NR_pkey_mprotect 386 #endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */ diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index b97366e..11a32b3 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -15,6 +15,17 @@ #include /* PKEY_* */ #include +#define pkeyshift(pkey) ((arch_max_pkey()-pkey-1) * AMR_BITS_PER_PKEY) + +static inline bool pkey_allows_readwrite(int pkey) +{ + int pkey_shift = pkeyshift(pkey); + + if (!(read_uamor() & (0x3UL << pkey_shift))) + return true; + + return !(read_amr() & ((AMR_AD_BIT|AMR_WD_BIT) << pkey_shift)); +} /* * set the access right in AMR IAMR and UAMOR register @@ -68,7 +79,60 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, int __execute_only_pkey(struct mm_struct *mm) { - return -1; + bool need_to_set_mm_pkey = false; + int execute_only_pkey = mm->context.execute_only_pkey; + int ret; + + /* Do we need to assign a pkey for mm's execute-only maps? */ + if (execute_only_pkey == -1) { + /* Go allocate one to use, which might fail */ + execute_only_pkey = mm_pkey_alloc(mm); + if (execute_only_pkey < 0) + return -1; + need_to_set_mm_pkey = true; + } + + /* + * We do not want to go through the relatively costly + * dance to set AMR if we do not need to. Check it + * first and assume that if the execute-only pkey is + * readwrite-disabled than we do not have to set it + * ourselves. + */ + if (!need_to_set_mm_pkey && + !pkey_allows_readwrite(execute_only_pkey)) + return execute_only_pkey; + + /* + * Set up AMR so that it denies access for everything + * other than execution. + */ + ret = __arch_set_user_pkey_access(current, execute_only_pkey, + (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)); + /* + * If the AMR-set operation failed somehow, just return + * 0 and effectively disable execute-only support. + */ + if (ret) { + mm_set_pkey_free(mm, execute_only_pkey); + return -1; + } + + /* We got one, store it and use it from here on out */ + if (need_to_set_mm_pkey) + mm->context.execute_only_pkey = execute_only_pkey; + return execute_only_pkey; +} + +static inline bool vma_is_pkey_exec_only(struct vm_area_struct *vma) +{ + /* Do this check first since the vm_flags should be hot */ + if ((vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) != VM_EXEC) + return false; + if (vma_pkey(vma) != vma->vm_mm->context.execute_only_pkey) + return false; + + return true; } /* @@ -84,5 +148,30 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, if (pkey != -1) return pkey; - return 0; + /* + * Look for a protection-key-drive execute-only mapping + * which is now being given permissions that are not + * execute-only. Move it back to the default pkey. + */ + if (vma_is_pkey_exec_only(vma) && + (prot & (PROT_READ|PROT_WRITE))) { + return 0; + } + /* + * The mapping is execute-only. Go try to get the + * execute-only protection key. If we fail to do that, + * fall through as if we do not have execute-only + * support. + */ + if (prot == PROT_EXEC) { + pkey = execute_only_pkey(vma->vm_mm); + if (pkey > 0) + return pkey; + } + /* + * This is a vanilla, non-pkey mprotect (or we failed to + * setup execute-only), inherit the pkey from the VMA we + * are working on. + */ + return vma_pkey(vma); } -- 1.8.3.1