diff options
Diffstat (limited to 'arch/arm64/include/asm/uaccess.h')
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 248 |
1 files changed, 219 insertions, 29 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 14450f742554..21963026efd0 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -18,6 +18,12 @@ #ifndef __ASM_UACCESS_H #define __ASM_UACCESS_H +#include <asm/alternative.h> +#include <asm/kernel-pgtable.h> +#include <asm/sysreg.h> + +#ifndef __ASSEMBLY__ + /* * User space memory access functions */ @@ -25,10 +31,8 @@ #include <linux/string.h> #include <linux/thread_info.h> -#include <asm/alternative.h> #include <asm/cpufeature.h> #include <asm/ptrace.h> -#include <asm/sysreg.h> #include <asm/errno.h> #include <asm/memory.h> #include <asm/compiler.h> @@ -65,6 +69,16 @@ extern int fixup_exception(struct pt_regs *regs); static inline void set_fs(mm_segment_t fs) { current_thread_info()->addr_limit = fs; + + /* + * Enable/disable UAO so that copy_to_user() etc can access + * kernel memory with the unprivileged instructions. + */ + if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS) + asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO)); + else + asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO, + CONFIG_ARM64_UAO)); } #define segment_eq(a,b) ((a) == (b)) @@ -115,6 +129,99 @@ static inline void set_fs(mm_segment_t fs) #define user_addr_max get_fs /* + * User access enabling/disabling. + */ +#ifdef CONFIG_ARM64_SW_TTBR0_PAN +static inline void __uaccess_ttbr0_disable(void) +{ + unsigned long ttbr; + + /* reserved_ttbr0 placed at the end of swapper_pg_dir */ + ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE; + write_sysreg(ttbr, ttbr0_el1); + isb(); +} + +static inline void __uaccess_ttbr0_enable(void) +{ + unsigned long flags; + + /* + * Disable interrupts to avoid preemption between reading the 'ttbr0' + * variable and the MSR. A context switch could trigger an ASID + * roll-over and an update of 'ttbr0'. + */ + local_irq_save(flags); + write_sysreg(current_thread_info()->ttbr0, ttbr0_el1); + isb(); + local_irq_restore(flags); +} + +static inline bool uaccess_ttbr0_disable(void) +{ + if (!system_uses_ttbr0_pan()) + return false; + __uaccess_ttbr0_disable(); + return true; +} + +static inline bool uaccess_ttbr0_enable(void) +{ + if (!system_uses_ttbr0_pan()) + return false; + __uaccess_ttbr0_enable(); + return true; +} +#else +static inline bool uaccess_ttbr0_disable(void) +{ + return false; +} + +static inline bool uaccess_ttbr0_enable(void) +{ + return false; +} +#endif + +#define __uaccess_disable(alt) \ +do { \ + if (!uaccess_ttbr0_disable()) \ + asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ + CONFIG_ARM64_PAN)); \ +} while (0) + +#define __uaccess_enable(alt) \ +do { \ + if (!uaccess_ttbr0_enable()) \ + asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ + CONFIG_ARM64_PAN)); \ +} while (0) + +static inline void uaccess_disable(void) +{ + __uaccess_disable(ARM64_HAS_PAN); +} + +static inline void uaccess_enable(void) +{ + __uaccess_enable(ARM64_HAS_PAN); +} + +/* + * These functions are no-ops when UAO is present. + */ +static inline void uaccess_disable_not_uao(void) +{ + __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); +} + +static inline void uaccess_enable_not_uao(void) +{ + __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); +} + +/* * The "__xxx" versions of the user access functions do not verify the address * space - it must have been done previously with a separate "access_ok()" * call. @@ -122,9 +229,10 @@ static inline void set_fs(mm_segment_t fs) * The "__xxx_error" versions set the third argument to -EFAULT if an error * occurs, and leave it unchanged on success. */ -#define __get_user_asm(instr, reg, x, addr, err) \ +#define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ asm volatile( \ - "1: " instr " " reg "1, [%2]\n" \ + "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ + alt_instr " " reg "1, [%2]\n", feature) \ "2:\n" \ " .section .fixup, \"ax\"\n" \ " .align 2\n" \ @@ -143,27 +251,29 @@ static inline void set_fs(mm_segment_t fs) do { \ unsigned long __gu_val; \ __chk_user_ptr(ptr); \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN)); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ - __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err)); \ + __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 2: \ - __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err)); \ + __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 4: \ - __get_user_asm("ldr", "%w", __gu_val, (ptr), (err)); \ + __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 8: \ - __get_user_asm("ldr", "%", __gu_val, (ptr), (err)); \ + __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ default: \ BUILD_BUG(); \ } \ + uaccess_disable_not_uao(); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN)); \ } while (0) #define __get_user(x, ptr) \ @@ -190,9 +300,10 @@ do { \ ((x) = 0, -EFAULT); \ }) -#define __put_user_asm(instr, reg, x, addr, err) \ +#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ asm volatile( \ - "1: " instr " " reg "1, [%2]\n" \ + "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ + alt_instr " " reg "1, [%2]\n", feature) \ "2:\n" \ " .section .fixup,\"ax\"\n" \ " .align 2\n" \ @@ -210,26 +321,28 @@ do { \ do { \ __typeof__(*(ptr)) __pu_val = (x); \ __chk_user_ptr(ptr); \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN)); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ - __put_user_asm("strb", "%w", __pu_val, (ptr), (err)); \ + __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 2: \ - __put_user_asm("strh", "%w", __pu_val, (ptr), (err)); \ + __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 4: \ - __put_user_asm("str", "%w", __pu_val, (ptr), (err)); \ + __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ case 8: \ - __put_user_asm("str", "%", __pu_val, (ptr), (err)); \ + __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ + (err), ARM64_HAS_UAO); \ break; \ default: \ BUILD_BUG(); \ } \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ - CONFIG_ARM64_PAN)); \ + uaccess_disable_not_uao(); \ } while (0) #define __put_user(x, ptr) \ @@ -256,24 +369,39 @@ do { \ -EFAULT; \ }) -extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); -extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); +extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); +extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); +static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n) +{ + check_object_size(to, n, false); + return __arch_copy_from_user(to, from, n); +} + +static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) +{ + check_object_size(from, n, true); + return __arch_copy_to_user(to, from, n); +} + static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { - if (access_ok(VERIFY_READ, from, n)) - n = __copy_from_user(to, from, n); - else /* security hole - plug it */ + if (access_ok(VERIFY_READ, from, n)) { + check_object_size(to, n, false); + n = __arch_copy_from_user(to, from, n); + } else /* security hole - plug it */ memset(to, 0, n); return n; } static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) { - if (access_ok(VERIFY_WRITE, to, n)) - n = __copy_to_user(to, from, n); + if (access_ok(VERIFY_WRITE, to, n)) { + check_object_size(from, n, true); + n = __arch_copy_to_user(to, from, n); + } return n; } @@ -299,4 +427,66 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *str, long n); +#else /* __ASSEMBLY__ */ + +#include <asm/assembler.h> + +/* + * User access enabling/disabling macros. + */ +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + .macro __uaccess_ttbr0_disable, tmp1 + mrs \tmp1, ttbr1_el1 // swapper_pg_dir + add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir + msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1 + isb + .endm + + .macro __uaccess_ttbr0_enable, tmp1 + get_thread_info \tmp1 + ldr \tmp1, [\tmp1, #TSK_TI_TTBR0] // load saved TTBR0_EL1 + msr ttbr0_el1, \tmp1 // set the non-PAN TTBR0_EL1 + isb + .endm + + .macro uaccess_ttbr0_disable, tmp1 +alternative_if_not ARM64_HAS_PAN + __uaccess_ttbr0_disable \tmp1 +alternative_else_nop_endif + .endm + + .macro uaccess_ttbr0_enable, tmp1, tmp2 +alternative_if_not ARM64_HAS_PAN + save_and_disable_irq \tmp2 // avoid preemption + __uaccess_ttbr0_enable \tmp1 + restore_irq \tmp2 +alternative_else_nop_endif + .endm +#else + .macro uaccess_ttbr0_disable, tmp1 + .endm + + .macro uaccess_ttbr0_enable, tmp1, tmp2 + .endm +#endif + +/* + * These macros are no-ops when UAO is present. + */ + .macro uaccess_disable_not_uao, tmp1 + uaccess_ttbr0_disable \tmp1 +alternative_if ARM64_ALT_PAN_NOT_UAO + SET_PSTATE_PAN(1) +alternative_else_nop_endif + .endm + + .macro uaccess_enable_not_uao, tmp1, tmp2 + uaccess_ttbr0_enable \tmp1, \tmp2 +alternative_if ARM64_ALT_PAN_NOT_UAO + SET_PSTATE_PAN(0) +alternative_else_nop_endif + .endm + +#endif /* __ASSEMBLY__ */ + #endif /* __ASM_UACCESS_H */ |