diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/kup-radix.h | 6 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/kup.h | 1 | ||||
| -rw-r--r-- | arch/powerpc/mm/fault.c | 25 |
3 files changed, 29 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h index 6d6628424134..7679bd0c5af0 100644 --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h @@ -95,6 +95,12 @@ static inline void prevent_user_access(void __user *to, const void __user *from, set_kuap(AMR_KUAP_BLOCKED); } +static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) +{ + return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) && + (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), + "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read"); +} #endif /* CONFIG_PPC_KUAP */ #endif /* __ASSEMBLY__ */ diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index d7312defbe1c..28ad4654eed2 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -26,6 +26,7 @@ static inline void allow_user_access(void __user *to, const void __user *from, unsigned long size) { } static inline void prevent_user_access(void __user *to, const void __user *from, unsigned long size) { } +static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write) { return false; } #endif /* CONFIG_PPC_KUAP */ static inline void allow_read_from_user(const void __user *from, unsigned long size) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 463d1e9d026e..b5d3578d9f65 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -44,6 +44,7 @@ #include <asm/mmu_context.h> #include <asm/siginfo.h> #include <asm/debug.h> +#include <asm/kup.h> static inline bool notify_page_fault(struct pt_regs *regs) { @@ -224,7 +225,7 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, /* Is this a bad kernel fault ? */ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, - unsigned long address) + unsigned long address, bool is_write) { int is_exec = TRAP(regs) == 0x400; @@ -235,6 +236,9 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, address >= TASK_SIZE ? "exec-protected" : "user", address, from_kuid(&init_user_ns, current_uid())); + + // Kernel exec fault is always bad + return true; } if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) && @@ -244,7 +248,22 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, from_kuid(&init_user_ns, current_uid())); } - return is_exec || (address >= TASK_SIZE) || !search_exception_tables(regs->nip); + // Kernel fault on kernel address is bad + if (address >= TASK_SIZE) + return true; + + // Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad + if (!search_exception_tables(regs->nip)) + return true; + + // Read/write fault in a valid region (the exception table search passed + // above), but blocked by KUAP is bad, it can never succeed. + if (bad_kuap_fault(regs, is_write)) + return true; + + // What's left? Kernel fault on user in well defined regions (extable + // matched), and allowed by KUAP in the faulting context. + return false; } static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address, @@ -467,7 +486,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, * take a page fault to a kernel address or a page fault to a user * address outside of dedicated places */ - if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address))) + if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write))) return SIGSEGV; /* |