diff options
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/mm/fault.c | 10 | ||||
| -rw-r--r-- | arch/x86/mm/pkeys.c | 101 |
3 files changed, 113 insertions, 0 deletions
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index f9d38a48e3c8..67cf2e1e557b 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -34,3 +34,5 @@ obj-$(CONFIG_ACPI_NUMA) += srat.o obj-$(CONFIG_NUMA_EMU) += numa_emulation.o obj-$(CONFIG_X86_INTEL_MPX) += mpx.o +obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o + diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index d81744e6f39f..5877b92ab6f1 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1108,6 +1108,16 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) */ if (error_code & PF_PK) return 1; + + if (!(error_code & PF_INSTR)) { + /* + * Assume all accesses require either read or execute + * permissions. This is not an instruction access, so + * it requires read permissions. + */ + if (!(vma->vm_flags & VM_READ)) + return 1; + } /* * Make sure to check the VMA so that we do not perform * faults just to hit a PF_PK as soon as we fill in a diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c new file mode 100644 index 000000000000..e8c474451928 --- /dev/null +++ b/arch/x86/mm/pkeys.c @@ -0,0 +1,101 @@ +/* + * Intel Memory Protection Keys management + * Copyright (c) 2015, Intel Corporation. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + */ +#include <linux/mm_types.h> /* mm_struct, vma, etc... */ +#include <linux/pkeys.h> /* PKEY_* */ +#include <uapi/asm-generic/mman-common.h> + +#include <asm/cpufeature.h> /* boot_cpu_has, ... */ +#include <asm/mmu_context.h> /* vma_pkey() */ +#include <asm/fpu/internal.h> /* fpregs_active() */ + +int __execute_only_pkey(struct mm_struct *mm) +{ + int ret; + + /* + * We do not want to go through the relatively costly + * dance to set PKRU if we do not need to. Check it + * first and assume that if the execute-only pkey is + * write-disabled that we do not have to set it + * ourselves. We need preempt off so that nobody + * can make fpregs inactive. + */ + preempt_disable(); + if (fpregs_active() && + !__pkru_allows_read(read_pkru(), PKEY_DEDICATED_EXECUTE_ONLY)) { + preempt_enable(); + return PKEY_DEDICATED_EXECUTE_ONLY; + } + preempt_enable(); + ret = arch_set_user_pkey_access(current, PKEY_DEDICATED_EXECUTE_ONLY, + PKEY_DISABLE_ACCESS); + /* + * If the PKRU-set operation failed somehow, just return + * 0 and effectively disable execute-only support. + */ + if (ret) + return 0; + + return PKEY_DEDICATED_EXECUTE_ONLY; +} + +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) != PKEY_DEDICATED_EXECUTE_ONLY) + return false; + + return true; +} + +/* + * This is only called for *plain* mprotect calls. + */ +int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, int pkey) +{ + /* + * Is this an mprotect_pkey() call? If so, never + * override the value that came from the user. + */ + if (pkey != -1) + return pkey; + /* + * 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); +} |