diff options
Diffstat (limited to 'arch/arm64/include/asm/uaccess.h')
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 490 |
1 files changed, 294 insertions, 196 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 32fc8061aa76..5b91803201ef 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -18,50 +18,25 @@ #include <linux/kasan-checks.h> #include <linux/string.h> +#include <asm/asm-extable.h> #include <asm/cpufeature.h> +#include <asm/mmu.h> +#include <asm/mte.h> #include <asm/ptrace.h> #include <asm/memory.h> #include <asm/extable.h> -#define get_fs() (current_thread_info()->addr_limit) - -static inline void set_fs(mm_segment_t fs) -{ - current_thread_info()->addr_limit = fs; - - /* - * Prevent a mispredicted conditional call to set_fs from forwarding - * the wrong address limit to access_ok under speculation. - */ - spec_bar(); - - /* On user-mode return, check fs is correct */ - set_thread_flag(TIF_FSCHECK); - - /* - * 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)) +static inline int __access_ok(const void __user *ptr, unsigned long size); /* * Test whether a block of memory is a valid user space address. * Returns 1 if the range is valid, 0 otherwise. * * This is equivalent to the following test: - * (u65)addr + (u65)size <= (u65)current->addr_limit + 1 + * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX */ -static inline unsigned long __range_ok(const void __user *addr, unsigned long size) +static inline int access_ok(const void __user *addr, unsigned long size) { - unsigned long ret, limit = current_thread_info()->addr_limit; - /* * Asynchronous I/O running in a kernel thread does not have the * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag @@ -71,35 +46,11 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) addr = untagged_addr(addr); - __chk_user_ptr(addr); - asm volatile( - // A + B <= C + 1 for all A,B,C, in four easy steps: - // 1: X = A + B; X' = X % 2^64 - " adds %0, %3, %2\n" - // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4 - " csel %1, xzr, %1, hi\n" - // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X' - // to compensate for the carry flag being set in step 4. For - // X > 2^64, X' merely has to remain nonzero, which it does. - " csinv %0, %0, xzr, cc\n" - // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1 - // comes from the carry in being clear. Otherwise, we are - // testing X' - C == 0, subject to the previous adjustments. - " sbcs xzr, %0, %1\n" - " cset %0, ls\n" - : "=&r" (ret), "+r" (limit) : "Ir" (size), "0" (addr) : "cc"); - - return ret; + return likely(__access_ok(addr, size)); } +#define access_ok access_ok -#define access_ok(addr, size) __range_ok(addr, size) -#define user_addr_max get_fs - -#define _ASM_EXTABLE(from, to) \ - " .pushsection __ex_table, \"a\"\n" \ - " .align 3\n" \ - " .long (" #from " - .), (" #to " - .)\n" \ - " .popsection\n" +#include <asm-generic/access_ok.h> /* * User access enabling/disabling. @@ -112,9 +63,8 @@ static inline void __uaccess_ttbr0_disable(void) local_irq_save(flags); ttbr = read_sysreg(ttbr1_el1); ttbr &= ~TTBR_ASID_MASK; - /* reserved_ttbr0 placed before swapper_pg_dir */ - write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1); - isb(); + /* reserved_pg_dir placed before swapper_pg_dir */ + write_sysreg(ttbr - RESERVED_SWAPPER_OFFSET, ttbr0_el1); /* Set reserved ASID */ write_sysreg(ttbr, ttbr1_el1); isb(); @@ -138,7 +88,6 @@ static inline void __uaccess_ttbr0_enable(void) ttbr1 &= ~TTBR_ASID_MASK; /* safety measure */ ttbr1 |= ttbr0 & TTBR_ASID_MASK; write_sysreg(ttbr1, ttbr1_el1); - isb(); /* Restore user page table */ write_sysreg(ttbr0, ttbr0_el1); @@ -185,47 +134,32 @@ static inline void __uaccess_enable_hw_pan(void) CONFIG_ARM64_PAN)); } -#define __uaccess_disable(alt) \ -do { \ - if (!uaccess_ttbr0_disable()) \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ - CONFIG_ARM64_PAN)); \ -} while (0) +static inline void uaccess_disable_privileged(void) +{ + mte_disable_tco(); -#define __uaccess_enable(alt) \ -do { \ - if (!uaccess_ttbr0_enable()) \ - asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ - CONFIG_ARM64_PAN)); \ -} while (0) + if (uaccess_ttbr0_disable()) + return; -static inline void uaccess_disable(void) -{ - __uaccess_disable(ARM64_HAS_PAN); + __uaccess_enable_hw_pan(); } -static inline void uaccess_enable(void) +static inline void uaccess_enable_privileged(void) { - __uaccess_enable(ARM64_HAS_PAN); -} + mte_enable_tco(); -/* - * These functions are no-ops when UAO is present. - */ -static inline void uaccess_disable_not_uao(void) -{ - __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); -} + if (uaccess_ttbr0_enable()) + return; -static inline void uaccess_enable_not_uao(void) -{ - __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); + __uaccess_disable_hw_pan(); } /* - * Sanitise a uaccess pointer such that it becomes NULL if above the - * current addr_limit. In case the pointer is tagged (has the top byte set), - * untag the pointer before checking. + * Sanitize a uaccess pointer such that it cannot reach any kernel address. + * + * Clearing bit 55 ensures the pointer cannot address any portion of the TTBR1 + * address range (i.e. any kernel address), and either the pointer falls within + * the TTBR0 address range or must cause a fault. */ #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) static inline void __user *__uaccess_mask_ptr(const void __user *ptr) @@ -233,14 +167,12 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) void __user *safe_ptr; asm volatile( - " bics xzr, %3, %2\n" - " csel %0, %1, xzr, eq\n" - : "=&r" (safe_ptr) - : "r" (ptr), "r" (current_thread_info()->addr_limit), - "r" (untagged_addr(ptr)) - : "cc"); - - csdb(); + " bic %0, %1, %2\n" + : "=r" (safe_ptr) + : "r" (ptr), + "i" (BIT(55)) + ); + return safe_ptr; } @@ -252,59 +184,81 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) * 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, alt_instr, reg, x, addr, err, feature) \ +#ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT +#define __get_mem_asm(load, reg, x, addr, label, type) \ + asm_goto_output( \ + "1: " load " " reg "0, [%1]\n" \ + _ASM_EXTABLE_##type##ACCESS(1b, %l2) \ + : "=r" (x) \ + : "r" (addr) : : label) +#else +#define __get_mem_asm(load, reg, x, addr, label, type) do { \ + int __gma_err = 0; \ asm volatile( \ - "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ - alt_instr " " reg "1, [%2]\n", feature) \ + "1: " load " " reg "1, [%2]\n" \ "2:\n" \ - " .section .fixup, \"ax\"\n" \ - " .align 2\n" \ - "3: mov %w0, %3\n" \ - " mov %1, #0\n" \ - " b 2b\n" \ - " .previous\n" \ - _ASM_EXTABLE(1b, 3b) \ - : "+r" (err), "=&r" (x) \ - : "r" (addr), "i" (-EFAULT)) - -#define __raw_get_user(x, ptr, err) \ + _ASM_EXTABLE_##type##ACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \ + : "+r" (__gma_err), "=r" (x) \ + : "r" (addr)); \ + if (__gma_err) goto label; } while (0) +#endif + +#define __raw_get_mem(ldr, x, ptr, label, type) \ +do { \ + unsigned long __gu_val; \ + switch (sizeof(*(ptr))) { \ + case 1: \ + __get_mem_asm(ldr "b", "%w", __gu_val, (ptr), label, type); \ + break; \ + case 2: \ + __get_mem_asm(ldr "h", "%w", __gu_val, (ptr), label, type); \ + break; \ + case 4: \ + __get_mem_asm(ldr, "%w", __gu_val, (ptr), label, type); \ + break; \ + case 8: \ + __get_mem_asm(ldr, "%x", __gu_val, (ptr), label, type); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ +} while (0) + +/* + * We must not call into the scheduler between uaccess_ttbr0_enable() and + * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions, + * we must evaluate these outside of the critical section. + */ +#define __raw_get_user(x, ptr, label) \ do { \ - unsigned long __gu_val; \ + __typeof__(*(ptr)) __user *__rgu_ptr = (ptr); \ + __typeof__(x) __rgu_val; \ __chk_user_ptr(ptr); \ - uaccess_enable_not_uao(); \ - switch (sizeof(*(ptr))) { \ - case 1: \ - __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ + do { \ + __label__ __rgu_failed; \ + uaccess_ttbr0_enable(); \ + __raw_get_mem("ldtr", __rgu_val, __rgu_ptr, __rgu_failed, U); \ + uaccess_ttbr0_disable(); \ + (x) = __rgu_val; \ break; \ - case 2: \ - __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ - break; \ - case 4: \ - __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ - break; \ - case 8: \ - __get_user_asm("ldr", "ldtr", "%x", __gu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ - break; \ - default: \ - BUILD_BUG(); \ - } \ - uaccess_disable_not_uao(); \ - (x) = (__force __typeof__(*(ptr)))__gu_val; \ + __rgu_failed: \ + uaccess_ttbr0_disable(); \ + goto label; \ + } while (0); \ } while (0) #define __get_user_error(x, ptr, err) \ do { \ + __label__ __gu_failed; \ __typeof__(*(ptr)) __user *__p = (ptr); \ might_fault(); \ if (access_ok(__p, sizeof(*__p))) { \ __p = uaccess_mask_ptr(__p); \ - __raw_get_user((x), __p, (err)); \ + __raw_get_user((x), __p, __gu_failed); \ } else { \ - (x) = 0; (err) = -EFAULT; \ + __gu_failed: \ + (x) = (__force __typeof__(x))0; (err) = -EFAULT; \ } \ } while (0) @@ -317,56 +271,90 @@ do { \ #define get_user __get_user -#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ - asm volatile( \ - "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ - alt_instr " " reg "1, [%2]\n", feature) \ - "2:\n" \ - " .section .fixup,\"ax\"\n" \ - " .align 2\n" \ - "3: mov %w0, %3\n" \ - " b 2b\n" \ - " .previous\n" \ - _ASM_EXTABLE(1b, 3b) \ - : "+r" (err) \ - : "r" (x), "r" (addr), "i" (-EFAULT)) - -#define __raw_put_user(x, ptr, err) \ +/* + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking + * functions, we must evaluate these outside of the critical section. + */ +#define __get_kernel_nofault(dst, src, type, err_label) \ do { \ - __typeof__(*(ptr)) __pu_val = (x); \ - __chk_user_ptr(ptr); \ - uaccess_enable_not_uao(); \ - switch (sizeof(*(ptr))) { \ - case 1: \ - __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ + __typeof__(dst) __gkn_dst = (dst); \ + __typeof__(src) __gkn_src = (src); \ + do { \ + __label__ __gkn_label; \ + \ + __mte_enable_tco_async(); \ + __raw_get_mem("ldr", *((type *)(__gkn_dst)), \ + (__force type *)(__gkn_src), __gkn_label, K); \ + __mte_disable_tco_async(); \ break; \ - case 2: \ - __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ - break; \ - case 4: \ - __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ - break; \ - case 8: \ - __put_user_asm("str", "sttr", "%x", __pu_val, (ptr), \ - (err), ARM64_HAS_UAO); \ + __gkn_label: \ + __mte_disable_tco_async(); \ + goto err_label; \ + } while (0); \ +} while (0) + +#define __put_mem_asm(store, reg, x, addr, label, type) \ + asm goto( \ + "1: " store " " reg "0, [%1]\n" \ + "2:\n" \ + _ASM_EXTABLE_##type##ACCESS(1b, %l2) \ + : : "rZ" (x), "r" (addr) : : label) + +#define __raw_put_mem(str, x, ptr, label, type) \ +do { \ + __typeof__(*(ptr)) __pu_val = (x); \ + switch (sizeof(*(ptr))) { \ + case 1: \ + __put_mem_asm(str "b", "%w", __pu_val, (ptr), label, type); \ + break; \ + case 2: \ + __put_mem_asm(str "h", "%w", __pu_val, (ptr), label, type); \ + break; \ + case 4: \ + __put_mem_asm(str, "%w", __pu_val, (ptr), label, type); \ + break; \ + case 8: \ + __put_mem_asm(str, "%x", __pu_val, (ptr), label, type); \ + break; \ + default: \ + BUILD_BUG(); \ + } \ +} while (0) + +/* + * We must not call into the scheduler between uaccess_ttbr0_enable() and + * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions, + * we must evaluate these outside of the critical section. + */ +#define __raw_put_user(x, ptr, label) \ +do { \ + __label__ __rpu_failed; \ + __typeof__(*(ptr)) __user *__rpu_ptr = (ptr); \ + __typeof__(*(ptr)) __rpu_val = (x); \ + __chk_user_ptr(__rpu_ptr); \ + \ + do { \ + uaccess_ttbr0_enable(); \ + __raw_put_mem("sttr", __rpu_val, __rpu_ptr, __rpu_failed, U); \ + uaccess_ttbr0_disable(); \ break; \ - default: \ - BUILD_BUG(); \ - } \ - uaccess_disable_not_uao(); \ + __rpu_failed: \ + uaccess_ttbr0_disable(); \ + goto label; \ + } while (0); \ } while (0) #define __put_user_error(x, ptr, err) \ do { \ + __label__ __pu_failed; \ __typeof__(*(ptr)) __user *__p = (ptr); \ might_fault(); \ if (access_ok(__p, sizeof(*__p))) { \ __p = uaccess_mask_ptr(__p); \ - __raw_put_user((x), __p, (err)); \ + __raw_put_user((x), __p, __pu_failed); \ } else { \ + __pu_failed: \ (err) = -EFAULT; \ } \ } while (0) @@ -380,14 +368,37 @@ do { \ #define put_user __put_user +/* + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking + * functions, we must evaluate these outside of the critical section. + */ +#define __put_kernel_nofault(dst, src, type, err_label) \ +do { \ + __typeof__(dst) __pkn_dst = (dst); \ + __typeof__(src) __pkn_src = (src); \ + \ + do { \ + __label__ __pkn_err; \ + __mte_enable_tco_async(); \ + __raw_put_mem("str", *((type *)(__pkn_src)), \ + (__force type *)(__pkn_dst), __pkn_err, K); \ + __mte_disable_tco_async(); \ + break; \ + __pkn_err: \ + __mte_disable_tco_async(); \ + goto err_label; \ + } while (0); \ +} while(0) + extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); #define raw_copy_from_user(to, from, n) \ ({ \ unsigned long __acfu_ret; \ - uaccess_enable_not_uao(); \ + uaccess_ttbr0_enable(); \ __acfu_ret = __arch_copy_from_user((to), \ __uaccess_mask_ptr(from), (n)); \ - uaccess_disable_not_uao(); \ + uaccess_ttbr0_disable(); \ __acfu_ret; \ }) @@ -395,23 +406,57 @@ extern unsigned long __must_check __arch_copy_to_user(void __user *to, const voi #define raw_copy_to_user(to, from, n) \ ({ \ unsigned long __actu_ret; \ - uaccess_enable_not_uao(); \ + uaccess_ttbr0_enable(); \ __actu_ret = __arch_copy_to_user(__uaccess_mask_ptr(to), \ (from), (n)); \ - uaccess_disable_not_uao(); \ + uaccess_ttbr0_disable(); \ __actu_ret; \ }) -extern unsigned long __must_check __arch_copy_in_user(void __user *to, const void __user *from, unsigned long n); -#define raw_copy_in_user(to, from, n) \ -({ \ - unsigned long __aciu_ret; \ - uaccess_enable_not_uao(); \ - __aciu_ret = __arch_copy_in_user(__uaccess_mask_ptr(to), \ - __uaccess_mask_ptr(from), (n)); \ - uaccess_disable_not_uao(); \ - __aciu_ret; \ -}) +static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) +{ + if (unlikely(!access_ok(ptr,len))) + return 0; + uaccess_ttbr0_enable(); + return 1; +} +#define user_access_begin(a,b) user_access_begin(a,b) +#define user_access_end() uaccess_ttbr0_disable() +#define unsafe_put_user(x, ptr, label) \ + __raw_put_mem("sttr", x, uaccess_mask_ptr(ptr), label, U) +#define unsafe_get_user(x, ptr, label) \ + __raw_get_mem("ldtr", x, uaccess_mask_ptr(ptr), label, U) + +/* + * KCSAN uses these to save and restore ttbr state. + * We do not support KCSAN with ARM64_SW_TTBR0_PAN, so + * they are no-ops. + */ +static inline unsigned long user_access_save(void) { return 0; } +static inline void user_access_restore(unsigned long enabled) { } + +/* + * We want the unsafe accessors to always be inlined and use + * the error labels - thus the macro games. + */ +#define unsafe_copy_loop(dst, src, len, type, label) \ + while (len >= sizeof(type)) { \ + unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ + dst += sizeof(type); \ + src += sizeof(type); \ + len -= sizeof(type); \ + } + +#define unsafe_copy_to_user(_dst,_src,_len,label) \ +do { \ + char __user *__ucu_dst = (_dst); \ + const char *__ucu_src = (_src); \ + size_t __ucu_len = (_len); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ + unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ +} while (0) #define INLINE_COPY_TO_USER #define INLINE_COPY_FROM_USER @@ -420,9 +465,9 @@ extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned lo static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n) { if (access_ok(to, n)) { - uaccess_enable_not_uao(); + uaccess_ttbr0_enable(); n = __arch_clear_user(__uaccess_mask_ptr(to), n); - uaccess_disable_not_uao(); + uaccess_ttbr0_disable(); } return n; } @@ -433,8 +478,6 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strnlen_user(const char __user *str, long n); #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE -struct page; -void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len); extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n); static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) @@ -444,4 +487,59 @@ static inline int __copy_from_user_flushcache(void *dst, const void __user *src, } #endif +#ifdef CONFIG_ARCH_HAS_SUBPAGE_FAULTS + +/* + * Return 0 on success, the number of bytes not probed otherwise. + */ +static inline size_t probe_subpage_writeable(const char __user *uaddr, + size_t size) +{ + if (!system_supports_mte()) + return 0; + return mte_probe_user_range(uaddr, size); +} + +#endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */ + +#ifdef CONFIG_ARM64_GCS + +static inline int gcssttr(unsigned long __user *addr, unsigned long val) +{ + register unsigned long __user *_addr __asm__ ("x0") = addr; + register unsigned long _val __asm__ ("x1") = val; + int err = 0; + + /* GCSSTTR x1, x0 */ + asm volatile( + "1: .inst 0xd91f1c01\n" + "2: \n" + _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) + : "+r" (err) + : "rZ" (_val), "r" (_addr) + : "memory"); + + return err; +} + +static inline void put_user_gcs(unsigned long val, unsigned long __user *addr, + int *err) +{ + int ret; + + if (!access_ok((char __user *)addr, sizeof(u64))) { + *err = -EFAULT; + return; + } + + uaccess_ttbr0_enable(); + ret = gcssttr(addr, val); + if (ret != 0) + *err = ret; + uaccess_ttbr0_disable(); +} + + +#endif /* CONFIG_ARM64_GCS */ + #endif /* __ASM_UACCESS_H */ |