arch/um/kernel/skas/uaccess.c - linux - Git at Google

 // 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 <asm/futex.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 (!access_ok(src, 1))
 		return -EFAULT;

 	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 char __user *str, long len)
 {
 	int count = 0, n;

 	if (!access_ok(str, 1))
 		return -EFAULT;

 	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);

 /**
  * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
  *			  argument and comparison of the previous
  *			  futex value with another constant.
  *
  * @encoded_op:	encoded operation to execute
  * @uaddr:	pointer to user space address
  *
  * Return:
  * 0 - On success
  * -EFAULT - User access resulted in a page fault
  * -EAGAIN - Atomic operation was unable to complete due to contention
  * -ENOSYS - Operation not supported
  */

 int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval, ret;
 	struct page *page;
 	unsigned long addr = (unsigned long) uaddr;
 	pte_t *pte;

 	ret = -EFAULT;
 	if (!access_ok(uaddr, sizeof(*uaddr)))
 		return -EFAULT;
 	preempt_disable();
 	pte = maybe_map(addr, 1);
 	if (pte == NULL)
 		goto out_inuser;

 	page = pte_page(*pte);
 #ifdef CONFIG_64BIT
 	pagefault_disable();
 	addr = (unsigned long) page_address(page) +
 			(((unsigned long) addr) & ~PAGE_MASK);
 #else
 	addr = (unsigned long) kmap_atomic(page) +
 		((unsigned long) addr & ~PAGE_MASK);
 #endif
 	uaddr = (u32 *) addr;
 	oldval = *uaddr;

 	ret = 0;

 	switch (op) {
 	case FUTEX_OP_SET:
 		*uaddr = oparg;
 		break;
 	case FUTEX_OP_ADD:
 		*uaddr += oparg;
 		break;
 	case FUTEX_OP_OR:
 		*uaddr |= oparg;
 		break;
 	case FUTEX_OP_ANDN:
 		*uaddr &= ~oparg;
 		break;
 	case FUTEX_OP_XOR:
 		*uaddr ^= oparg;
 		break;
 	default:
 		ret = -ENOSYS;
 	}
 #ifdef CONFIG_64BIT
 	pagefault_enable();
 #else
 	kunmap_atomic((void *)addr);
 #endif

 out_inuser:
 	preempt_enable();

 	if (ret == 0)
 		*oval = oldval;

 	return ret;
 }
 EXPORT_SYMBOL(arch_futex_atomic_op_inuser);

 /**
  * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
  *				uaddr with newval if the current value is
  *				oldval.
  * @uval:	pointer to store content of @uaddr
  * @uaddr:	pointer to user space address
  * @oldval:	old value
  * @newval:	new value to store to @uaddr
  *
  * Return:
  * 0 - On success
  * -EFAULT - User access resulted in a page fault
  * -EAGAIN - Atomic operation was unable to complete due to contention
  * -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
  */

 int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 			      u32 oldval, u32 newval)
 {
 	struct page *page;
 	pte_t *pte;
 	int ret = -EFAULT;

 	if (!access_ok(uaddr, sizeof(*uaddr)))
 		return -EFAULT;

 	preempt_disable();
 	pte = maybe_map((unsigned long) uaddr, 1);
 	if (pte == NULL)
 		goto out_inatomic;

 	page = pte_page(*pte);
 #ifdef CONFIG_64BIT
 	pagefault_disable();
 	uaddr = page_address(page) + (((unsigned long) uaddr) & ~PAGE_MASK);
 #else
 	uaddr = kmap_atomic(page) + ((unsigned long) uaddr & ~PAGE_MASK);
 #endif

 	*uval = *uaddr;

 	ret = cmpxchg(uaddr, oldval, newval);

 #ifdef CONFIG_64BIT
 	pagefault_enable();
 #else
 	kunmap_atomic(uaddr);
 #endif
 	ret = 0;

 out_inatomic:
 	preempt_enable();
 	return ret;
 }
 EXPORT_SYMBOL(futex_atomic_cmpxchg_inatomic);
	// 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 <asm/futex.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 (!access_ok(src, 1))
	return -EFAULT;

	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 char __user *str, long len)
	{
	int count = 0, n;

	if (!access_ok(str, 1))
	return -EFAULT;

	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);

	/**
	* arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
	* argument and comparison of the previous
	* futex value with another constant.
	*
	* @encoded_op: encoded operation to execute
	* @uaddr: pointer to user space address
	*
	* Return:
	* 0 - On success
	* -EFAULT - User access resulted in a page fault
	* -EAGAIN - Atomic operation was unable to complete due to contention
	* -ENOSYS - Operation not supported
	*/

	int arch_futex_atomic_op_inuser(int op, u32 oparg, int oval, u32 __user uaddr)
	{
	int oldval, ret;
	struct page *page;
	unsigned long addr = (unsigned long) uaddr;
	pte_t *pte;

	ret = -EFAULT;
	if (!access_ok(uaddr, sizeof(*uaddr)))
	return -EFAULT;
	preempt_disable();
	pte = maybe_map(addr, 1);
	if (pte == NULL)
	goto out_inuser;

	page = pte_page(*pte);
	#ifdef CONFIG_64BIT
	pagefault_disable();
	addr = (unsigned long) page_address(page) +
	(((unsigned long) addr) & ~PAGE_MASK);
	#else
	addr = (unsigned long) kmap_atomic(page) +
	((unsigned long) addr & ~PAGE_MASK);
	#endif
	uaddr = (u32 *) addr;
	oldval = *uaddr;

	ret = 0;

	switch (op) {
	case FUTEX_OP_SET:
	*uaddr = oparg;
	break;
	case FUTEX_OP_ADD:
	*uaddr += oparg;
	break;
	case FUTEX_OP_OR:
	*uaddr \|= oparg;
	break;
	case FUTEX_OP_ANDN:
	*uaddr &= ~oparg;
	break;
	case FUTEX_OP_XOR:
	*uaddr ^= oparg;
	break;
	default:
	ret = -ENOSYS;
	}
	#ifdef CONFIG_64BIT
	pagefault_enable();
	#else
	kunmap_atomic((void *)addr);
	#endif

	out_inuser:
	preempt_enable();

	if (ret == 0)
	*oval = oldval;

	return ret;
	}
	EXPORT_SYMBOL(arch_futex_atomic_op_inuser);

	/**
	* futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
	* uaddr with newval if the current value is
	* oldval.
	* @uval: pointer to store content of @uaddr
	* @uaddr: pointer to user space address
	* @oldval: old value
	* @newval: new value to store to @uaddr
	*
	* Return:
	* 0 - On success
	* -EFAULT - User access resulted in a page fault
	* -EAGAIN - Atomic operation was unable to complete due to contention
	* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
	*/

	int futex_atomic_cmpxchg_inatomic(u32 uval, u32 __user uaddr,
	u32 oldval, u32 newval)
	{
	struct page *page;
	pte_t *pte;
	int ret = -EFAULT;

	if (!access_ok(uaddr, sizeof(*uaddr)))
	return -EFAULT;

	preempt_disable();
	pte = maybe_map((unsigned long) uaddr, 1);
	if (pte == NULL)
	goto out_inatomic;

	page = pte_page(*pte);
	#ifdef CONFIG_64BIT
	pagefault_disable();
	uaddr = page_address(page) + (((unsigned long) uaddr) & ~PAGE_MASK);
	#else
	uaddr = kmap_atomic(page) + ((unsigned long) uaddr & ~PAGE_MASK);
	#endif

	uval = uaddr;

	ret = cmpxchg(uaddr, oldval, newval);

	#ifdef CONFIG_64BIT
	pagefault_enable();
	#else
	kunmap_atomic(uaddr);
	#endif
	ret = 0;

	out_inatomic:
	preempt_enable();
	return ret;
	}
	EXPORT_SYMBOL(futex_atomic_cmpxchg_inatomic);