diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 19:22:39 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 19:48:54 +0100 |
| commit | 786889636ad75296c213547d1ca656af4c59f390 (patch) | |
| tree | e8b249f00fbaf7a75dd05fa9d318d9a8f9c02f2c /arch/arm64/mm | |
| parent | arm64: Disable TTBR0_EL1 during normal kernel execution (diff) | |
| download | linux-786889636ad75296c213547d1ca656af4c59f390.tar.xz linux-786889636ad75296c213547d1ca656af4c59f390.zip | |
arm64: Handle faults caused by inadvertent user access with PAN enabled
When TTBR0_EL1 is set to the reserved page, an erroneous kernel access
to user space would generate a translation fault. This patch adds the
checks for the software-set PSR_PAN_BIT to emulate a permission fault
and report it accordingly.
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm')
| -rw-r--r-- | arch/arm64/mm/fault.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index d035cc594445..a78a5c401806 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -269,13 +269,19 @@ out: return fault; } -static inline bool is_permission_fault(unsigned int esr) +static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs) { unsigned int ec = ESR_ELx_EC(esr); unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE; - return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM) || - (ec == ESR_ELx_EC_IABT_CUR && fsc_type == ESR_ELx_FSC_PERM); + if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR) + return false; + + if (system_uses_ttbr0_pan()) + return fsc_type == ESR_ELx_FSC_FAULT && + (regs->pstate & PSR_PAN_BIT); + else + return fsc_type == ESR_ELx_FSC_PERM; } static bool is_el0_instruction_abort(unsigned int esr) @@ -315,7 +321,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, mm_flags |= FAULT_FLAG_WRITE; } - if (is_permission_fault(esr) && (addr < USER_DS)) { + if (addr < USER_DS && is_permission_fault(esr, regs)) { /* regs->orig_addr_limit may be 0 if we entered from EL0 */ if (regs->orig_addr_limit == KERNEL_DS) die("Accessing user space memory with fs=KERNEL_DS", regs, esr); |