From 87bbabbed8a77092135f6442b8d5619906a81255 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Thu, 18 Jan 2018 17:50:34 -0800 Subject: [PATCH] powerpc: implementation for arch_override_mprotect_pkey() arch independent code calls arch_override_mprotect_pkey() to return a pkey that best matches the requested protection. This patch provides the implementation. Signed-off-by: Ram Pai Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/mmu_context.h | 5 +++++ arch/powerpc/include/asm/pkeys.h | 21 +++++++++++++++++++- arch/powerpc/mm/pkeys.c | 36 ++++++++++++++++++++++++++++++++++ 3 files changed, 61 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h index 4d69223d217a..3ba571dfdfd9 100644 --- a/arch/powerpc/include/asm/mmu_context.h +++ b/arch/powerpc/include/asm/mmu_context.h @@ -198,6 +198,11 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma, #define thread_pkey_regs_save(thread) #define thread_pkey_regs_restore(new_thread, old_thread) #define thread_pkey_regs_init(thread) + +static inline int vma_pkey(struct vm_area_struct *vma) +{ + return 0; +} #endif /* CONFIG_PPC_MEM_KEYS */ #endif /* __KERNEL__ */ diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index df372557ec33..24e82260052f 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -41,6 +41,13 @@ static inline u64 pkey_to_vmflag_bits(u16 pkey) return (((u64)pkey << VM_PKEY_SHIFT) & ARCH_VM_PKEY_FLAGS); } +static inline int vma_pkey(struct vm_area_struct *vma) +{ + if (static_branch_likely(&pkey_disabled)) + return 0; + return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; +} + #define arch_max_pkey() pkeys_total #define pkey_alloc_mask(pkey) (0x1 << pkey) @@ -137,10 +144,22 @@ static inline int execute_only_pkey(struct mm_struct *mm) return __execute_only_pkey(mm); } +extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, + int prot, int pkey); static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, int pkey) { - return 0; + if (static_branch_likely(&pkey_disabled)) + return 0; + + /* + * Is this an mprotect_pkey() call? If so, never override the value that + * came from the user. + */ + if (pkey != -1) + return pkey; + + return __arch_override_mprotect_pkey(vma, prot, pkey); } extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index a4aac75f1a93..010c90c1f5da 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -322,3 +322,39 @@ int __execute_only_pkey(struct mm_struct *mm) 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; + + return (vma_pkey(vma) == vma->vm_mm->context.execute_only_pkey); +} + +/* + * This should only be called for *plain* mprotect calls. + */ +int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, + int pkey) +{ + /* + * If the currently associated pkey is execute-only, but the requested + * protection requires read or write, move it back to the default pkey. + */ + if (vma_is_pkey_exec_only(vma) && (prot & (PROT_READ | PROT_WRITE))) + return 0; + + /* + * The requested protection is execute-only. Hence let's use an + * execute-only pkey. + */ + if (prot == PROT_EXEC) { + pkey = execute_only_pkey(vma->vm_mm); + if (pkey > 0) + return pkey; + } + + /* Nothing to override. */ + return vma_pkey(vma); +} -- 2.11.0