mirror of
https://github.com/torvalds/linux
synced 2024-10-15 07:47:34 +00:00
113eeb5177
In preparation for further refactoring of kernel_read_file*(), rename the "max_size" argument to the more accurate "buf_size", and correct its type to size_t. Add kerndoc to explain the specifics of how the arguments will be used. Note that with buf_size now size_t, it can no longer be negative (and was never called with a negative value). Adjust callers to use it as a "maximum size" when *buf is NULL. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Acked-by: Scott Branden <scott.branden@broadcom.com> Link: https://lore.kernel.org/r/20201002173828.2099543-7-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
153 lines
3.1 KiB
C
153 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
#include <linux/fs.h>
|
|
#include <linux/fs_struct.h>
|
|
#include <linux/kernel_read_file.h>
|
|
#include <linux/security.h>
|
|
#include <linux/vmalloc.h>
|
|
|
|
/**
|
|
* kernel_read_file() - read file contents into a kernel buffer
|
|
*
|
|
* @file file to read from
|
|
* @buf pointer to a "void *" buffer for reading into (if
|
|
* *@buf is NULL, a buffer will be allocated, and
|
|
* @buf_size will be ignored)
|
|
* @buf_size size of buf, if already allocated. If @buf not
|
|
* allocated, this is the largest size to allocate.
|
|
* @id the kernel_read_file_id identifying the type of
|
|
* file contents being read (for LSMs to examine)
|
|
*
|
|
* Returns number of bytes read (no single read will be bigger
|
|
* than INT_MAX), or negative on error.
|
|
*
|
|
*/
|
|
int kernel_read_file(struct file *file, void **buf,
|
|
size_t buf_size, enum kernel_read_file_id id)
|
|
{
|
|
loff_t i_size, pos;
|
|
ssize_t bytes = 0;
|
|
void *allocated = NULL;
|
|
int ret;
|
|
|
|
if (!S_ISREG(file_inode(file)->i_mode))
|
|
return -EINVAL;
|
|
|
|
ret = deny_write_access(file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = security_kernel_read_file(file, id);
|
|
if (ret)
|
|
goto out;
|
|
|
|
i_size = i_size_read(file_inode(file));
|
|
if (i_size <= 0) {
|
|
ret = -EINVAL;
|
|
goto out;
|
|
}
|
|
if (i_size > INT_MAX || i_size > buf_size) {
|
|
ret = -EFBIG;
|
|
goto out;
|
|
}
|
|
|
|
if (!*buf)
|
|
*buf = allocated = vmalloc(i_size);
|
|
if (!*buf) {
|
|
ret = -ENOMEM;
|
|
goto out;
|
|
}
|
|
|
|
pos = 0;
|
|
while (pos < i_size) {
|
|
bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
|
|
if (bytes < 0) {
|
|
ret = bytes;
|
|
goto out_free;
|
|
}
|
|
|
|
if (bytes == 0)
|
|
break;
|
|
}
|
|
|
|
if (pos != i_size) {
|
|
ret = -EIO;
|
|
goto out_free;
|
|
}
|
|
|
|
ret = security_kernel_post_read_file(file, *buf, i_size, id);
|
|
|
|
out_free:
|
|
if (ret < 0) {
|
|
if (allocated) {
|
|
vfree(*buf);
|
|
*buf = NULL;
|
|
}
|
|
}
|
|
|
|
out:
|
|
allow_write_access(file);
|
|
return ret == 0 ? pos : ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernel_read_file);
|
|
|
|
int kernel_read_file_from_path(const char *path, void **buf,
|
|
size_t buf_size, enum kernel_read_file_id id)
|
|
{
|
|
struct file *file;
|
|
int ret;
|
|
|
|
if (!path || !*path)
|
|
return -EINVAL;
|
|
|
|
file = filp_open(path, O_RDONLY, 0);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
ret = kernel_read_file(file, buf, buf_size, id);
|
|
fput(file);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
|
|
|
|
int kernel_read_file_from_path_initns(const char *path, void **buf,
|
|
size_t buf_size,
|
|
enum kernel_read_file_id id)
|
|
{
|
|
struct file *file;
|
|
struct path root;
|
|
int ret;
|
|
|
|
if (!path || !*path)
|
|
return -EINVAL;
|
|
|
|
task_lock(&init_task);
|
|
get_fs_root(init_task.fs, &root);
|
|
task_unlock(&init_task);
|
|
|
|
file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
|
|
path_put(&root);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
ret = kernel_read_file(file, buf, buf_size, id);
|
|
fput(file);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
|
|
|
|
int kernel_read_file_from_fd(int fd, void **buf, size_t buf_size,
|
|
enum kernel_read_file_id id)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int ret = -EBADF;
|
|
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
ret = kernel_read_file(f.file, buf, buf_size, id);
|
|
out:
|
|
fdput(f);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
|