diff options
Diffstat (limited to 'arch/um/kernel/skas/uaccess.c')
| -rw-r--r-- | arch/um/kernel/skas/uaccess.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c new file mode 100644 index 000000000..2dec915ab --- /dev/null +++ b/arch/um/kernel/skas/uaccess.c @@ -0,0 +1,250 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <linux/err.h> +#include <linux/highmem.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <asm/current.h> +#include <asm/page.h> +#include <kern_util.h> +#include <os.h> + +pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + + if (mm == NULL) + return NULL; + + pgd = pgd_offset(mm, addr); + if (!pgd_present(*pgd)) + return NULL; + + p4d = p4d_offset(pgd, addr); + if (!p4d_present(*p4d)) + return NULL; + + pud = pud_offset(p4d, addr); + if (!pud_present(*pud)) + return NULL; + + pmd = pmd_offset(pud, addr); + if (!pmd_present(*pmd)) + return NULL; + + return pte_offset_kernel(pmd, addr); +} + +static pte_t *maybe_map(unsigned long virt, int is_write) +{ + pte_t *pte = virt_to_pte(current->mm, virt); + int err, dummy_code; + + if ((pte == NULL) || !pte_present(*pte) || + (is_write && !pte_write(*pte))) { + err = handle_page_fault(virt, 0, is_write, 1, &dummy_code); + if (err) + return NULL; + pte = virt_to_pte(current->mm, virt); + } + if (!pte_present(*pte)) + pte = NULL; + + return pte; +} + +static int do_op_one_page(unsigned long addr, int len, int is_write, + int (*op)(unsigned long addr, int len, void *arg), void *arg) +{ + struct page *page; + pte_t *pte; + int n; + + pte = maybe_map(addr, is_write); + if (pte == NULL) + return -1; + + page = pte_page(*pte); +#ifdef CONFIG_64BIT + pagefault_disable(); + addr = (unsigned long) page_address(page) + + (addr & ~PAGE_MASK); +#else + addr = (unsigned long) kmap_atomic(page) + + (addr & ~PAGE_MASK); +#endif + n = (*op)(addr, len, arg); + +#ifdef CONFIG_64BIT + pagefault_enable(); +#else + kunmap_atomic((void *)addr); +#endif + + return n; +} + +static long buffer_op(unsigned long addr, int len, int is_write, + int (*op)(unsigned long, int, void *), void *arg) +{ + long size, remain, n; + + size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len); + remain = len; + + n = do_op_one_page(addr, size, is_write, op, arg); + if (n != 0) { + remain = (n < 0 ? remain : 0); + goto out; + } + + addr += size; + remain -= size; + if (remain == 0) + goto out; + + while (addr < ((addr + remain) & PAGE_MASK)) { + n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg); + if (n != 0) { + remain = (n < 0 ? remain : 0); + goto out; + } + + addr += PAGE_SIZE; + remain -= PAGE_SIZE; + } + if (remain == 0) + goto out; + + n = do_op_one_page(addr, remain, is_write, op, arg); + if (n != 0) { + remain = (n < 0 ? remain : 0); + goto out; + } + + return 0; + out: + return remain; +} + +static int copy_chunk_from_user(unsigned long from, int len, void *arg) +{ + unsigned long *to_ptr = arg, to = *to_ptr; + + memcpy((void *) to, (void *) from, len); + *to_ptr += len; + return 0; +} + +unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n) +{ + if (uaccess_kernel()) { + memcpy(to, (__force void*)from, n); + return 0; + } + + return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to); +} +EXPORT_SYMBOL(raw_copy_from_user); + +static int copy_chunk_to_user(unsigned long to, int len, void *arg) +{ + unsigned long *from_ptr = arg, from = *from_ptr; + + memcpy((void *) to, (void *) from, len); + *from_ptr += len; + return 0; +} + +unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n) +{ + if (uaccess_kernel()) { + memcpy((__force void *) to, from, n); + return 0; + } + + return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from); +} +EXPORT_SYMBOL(raw_copy_to_user); + +static int strncpy_chunk_from_user(unsigned long from, int len, void *arg) +{ + char **to_ptr = arg, *to = *to_ptr; + int n; + + strncpy(to, (void *) from, len); + n = strnlen(to, len); + *to_ptr += n; + + if (n < len) + return 1; + return 0; +} + +long __strncpy_from_user(char *dst, const char __user *src, long count) +{ + long n; + char *ptr = dst; + + if (uaccess_kernel()) { + strncpy(dst, (__force void *) src, count); + return strnlen(dst, count); + } + + n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user, + &ptr); + if (n != 0) + return -EFAULT; + return strnlen(dst, count); +} +EXPORT_SYMBOL(__strncpy_from_user); + +static int clear_chunk(unsigned long addr, int len, void *unused) +{ + memset((void *) addr, 0, len); + return 0; +} + +unsigned long __clear_user(void __user *mem, unsigned long len) +{ + if (uaccess_kernel()) { + memset((__force void*)mem, 0, len); + return 0; + } + + return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL); +} +EXPORT_SYMBOL(__clear_user); + +static int strnlen_chunk(unsigned long str, int len, void *arg) +{ + int *len_ptr = arg, n; + + n = strnlen((void *) str, len); + *len_ptr += n; + + if (n < len) + return 1; + return 0; +} + +long __strnlen_user(const void __user *str, long len) +{ + int count = 0, n; + + if (uaccess_kernel()) + return strnlen((__force char*)str, len) + 1; + + n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count); + if (n == 0) + return count + 1; + return 0; +} +EXPORT_SYMBOL(__strnlen_user); |