mirror of
https://github.com/drasko/codezero.git
synced 2026-08-26 00:00:06 +02:00
Moved user buffer access functions to user.c
This commit is contained in:
Bahadir Balban
@@ -221,192 +221,6 @@ Dynamic Linking.
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Copy from one buffer to another. Stop if maxlength or
|
||||
* a page boundary is hit.
|
||||
*/
|
||||
int strncpy_page(void *to_ptr, void *from_ptr, int maxlength)
|
||||
{
|
||||
int count = 0;
|
||||
char *to = to_ptr, *from = from_ptr;
|
||||
|
||||
do {
|
||||
if ((to[count] = from[count]) == '\0') {
|
||||
count++;
|
||||
break;
|
||||
} else
|
||||
count++;
|
||||
} while (count < maxlength && !page_boundary(&from[count]));
|
||||
|
||||
if (page_boundary(&from[count]))
|
||||
return -EFAULT;
|
||||
if (count == maxlength)
|
||||
return -E2BIG;
|
||||
|
||||
return count;
|
||||
}
|
||||
|
||||
/*
|
||||
* Copy from one buffer to another. Stop if maxlength or
|
||||
* a page boundary is hit. Breaks if unsigned long sized copy value is 0,
|
||||
* as opposed to a 0 byte as in string copy. If byte size 0 was used
|
||||
* a valid pointer with a 0 byte in it would give a false termination.
|
||||
*/
|
||||
int bufncpy_page(void *to_ptr, void *from_ptr, int maxlength)
|
||||
{
|
||||
int count = 0;
|
||||
unsigned long *to = to_ptr, *from = from_ptr;
|
||||
|
||||
do {
|
||||
if ((to[count] = from[count]) == 0) {
|
||||
count++;
|
||||
break;
|
||||
} else
|
||||
count++;
|
||||
} while (count < maxlength && !page_boundary(&from[count]));
|
||||
|
||||
if (page_boundary(&from[count]))
|
||||
return -EFAULT;
|
||||
if (count == maxlength)
|
||||
return -E2BIG;
|
||||
|
||||
return count;
|
||||
}
|
||||
|
||||
/*
|
||||
* Copies a variable sized userspace string or array of pointers
|
||||
* (think &argv[0]), into buffer. If a page boundary is hit,
|
||||
* unmaps the previous page, validates and maps the new page.
|
||||
*/
|
||||
int copy_user_buf(struct tcb *task, void *buf, char *user, int maxlength,
|
||||
int elem_size)
|
||||
{
|
||||
int count = maxlength;
|
||||
int copied = 0, ret = 0, total = 0;
|
||||
void *mapped = 0;
|
||||
int (*copy_func)(void *, void *, int count);
|
||||
|
||||
/* This bit determines what size copier function to use. */
|
||||
if (elem_size == sizeof(char))
|
||||
copy_func = strncpy_page;
|
||||
else if (elem_size == sizeof(unsigned long))
|
||||
copy_func = bufncpy_page;
|
||||
else
|
||||
return -EINVAL;
|
||||
|
||||
/* Map the first page the user buffer is in */
|
||||
if (!(mapped = pager_validate_map_user_range(task, user,
|
||||
TILL_PAGE_ENDS(user),
|
||||
VM_READ)))
|
||||
return -EINVAL;
|
||||
|
||||
while ((ret = copy_func(buf + copied, mapped, count)) < 0) {
|
||||
if (ret == -E2BIG)
|
||||
return ret;
|
||||
else if (ret == -EFAULT) {
|
||||
/*
|
||||
* Copied is always in bytes no matter what elem_size is
|
||||
* because we know we hit a page boundary and we increase
|
||||
* by the page boundary bytes
|
||||
*/
|
||||
pager_unmap_user_range(mapped, TILL_PAGE_ENDS(mapped));
|
||||
copied += TILL_PAGE_ENDS(mapped);
|
||||
count -= TILL_PAGE_ENDS(mapped);
|
||||
if (!(mapped =
|
||||
pager_validate_map_user_range(task, user + copied,
|
||||
TILL_PAGE_ENDS(user + copied),
|
||||
VM_READ)))
|
||||
return -EINVAL;
|
||||
}
|
||||
}
|
||||
|
||||
/* Note copied is always in bytes */
|
||||
total = (copied / elem_size) + ret;
|
||||
|
||||
/* Unmap the final page */
|
||||
pager_unmap_user_range(mapped, TILL_PAGE_ENDS(mapped));
|
||||
|
||||
return total;
|
||||
}
|
||||
|
||||
/*
|
||||
* Calls copy_user_buf with char-sized copying. This matters because
|
||||
* buffer is variable and the terminator must be in char size
|
||||
*/
|
||||
static inline int
|
||||
copy_user_string(struct tcb *task, void *buf, char *user,
|
||||
int maxlength)
|
||||
{
|
||||
return copy_user_buf(task, buf, user, maxlength, sizeof(char));
|
||||
}
|
||||
|
||||
/*
|
||||
* Calls copy_user_buf with unsigned long sized copying. This matters
|
||||
* because buffer is variable and the terminator must be in ulong size
|
||||
*/
|
||||
static inline int
|
||||
copy_user_ptrs(struct tcb *task, void *buf, char *user,
|
||||
int maxlength)
|
||||
{
|
||||
return copy_user_buf(task, buf, user, maxlength, sizeof(unsigned long));
|
||||
}
|
||||
|
||||
|
||||
int copy_user_args(struct tcb *task, struct args_struct *args,
|
||||
void *argv_user, int args_max)
|
||||
{
|
||||
char **argv = 0;
|
||||
void *argsbuf;
|
||||
char *curbuf;
|
||||
int argc = 0;
|
||||
int used;
|
||||
int count;
|
||||
|
||||
if (!(argsbuf = kzalloc(args_max)))
|
||||
return -ENOMEM;
|
||||
|
||||
/*
|
||||
* First, copy the null-terminated array of
|
||||
* pointers to argument strings.
|
||||
*/
|
||||
if ((count = copy_user_ptrs(task, argsbuf, argv_user, args_max)) < 0)
|
||||
goto out;
|
||||
|
||||
/* On success, we get the number of arg strings + the terminator */
|
||||
argc = count - 1;
|
||||
used = count * sizeof(char *);
|
||||
argv = argsbuf;
|
||||
curbuf = argsbuf + used;
|
||||
|
||||
/* Now we copy each argument string into buffer */
|
||||
for (int i = 0; i < argc; i++) {
|
||||
/* Copy string into empty space in buffer */
|
||||
if ((count = copy_user_string(task, curbuf, argv[i],
|
||||
args_max - used)) < 0)
|
||||
goto out;
|
||||
|
||||
/* Replace pointer to string with copied location */
|
||||
argv[i] = curbuf;
|
||||
|
||||
/* Update current empty buffer location */
|
||||
curbuf += count;
|
||||
|
||||
/* Increase used buffer count */
|
||||
used += count;
|
||||
}
|
||||
|
||||
/* Set up the args struct */
|
||||
args->argc = argc;
|
||||
args->argv = argv;
|
||||
args->size = used;
|
||||
|
||||
return 0;
|
||||
|
||||
out:
|
||||
kfree(argsbuf);
|
||||
return count;
|
||||
}
|
||||
|
||||
int sys_execve(struct tcb *sender, char *pathname, char *argv[], char *envp[])
|
||||
{
|
||||
int ret;
|
||||
|
||||
Reference in New Issue
Block a user