fs/kernel_read_file: Split into separate source file

These routines are used in places outside of exec(2), so in preparation
for refactoring them, move them into a separate source file,
fs/kernel_read_file.c.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-5-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kees Cook 2020-10-02 10:38:16 -07:00 committed by Greg Kroah-Hartman
parent b89999d004
commit 5287b07f6d
3 changed files with 140 additions and 133 deletions

View File

@ -13,7 +13,8 @@ obj-y := open.o read_write.o file_table.o super.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o splice.o sync.o utimes.o d_path.o \
stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \
fs_types.o fs_context.o fs_parser.o fsopen.o init.o
fs_types.o fs_context.o fs_parser.o fsopen.o init.o \
kernel_read_file.o
ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o block_dev.o direct-io.o mpage.o

132
fs/exec.c
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@ -950,138 +950,6 @@ struct file *open_exec(const char *name)
}
EXPORT_SYMBOL(open_exec);
int kernel_read_file(struct file *file, void **buf, loff_t *size,
loff_t max_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) || max_size < 0)
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 > SIZE_MAX || (max_size > 0 && i_size > max_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);
if (!ret)
*size = pos;
out_free:
if (ret < 0) {
if (allocated) {
vfree(*buf);
*buf = NULL;
}
}
out:
allow_write_access(file);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file);
int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
loff_t max_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, size, max_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,
loff_t *size, loff_t max_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, size, max_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, loff_t *size, loff_t max_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, size, max_size, id);
out:
fdput(f);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
#if defined(CONFIG_HAVE_AOUT) || defined(CONFIG_BINFMT_FLAT) || \
defined(CONFIG_BINFMT_ELF_FDPIC)
ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)

138
fs/kernel_read_file.c Normal file
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@ -0,0 +1,138 @@
// 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>
int kernel_read_file(struct file *file, void **buf, loff_t *size,
loff_t max_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) || max_size < 0)
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 > SIZE_MAX || (max_size > 0 && i_size > max_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);
if (!ret)
*size = pos;
out_free:
if (ret < 0) {
if (allocated) {
vfree(*buf);
*buf = NULL;
}
}
out:
allow_write_access(file);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file);
int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
loff_t max_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, size, max_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,
loff_t *size, loff_t max_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, size, max_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, loff_t *size, loff_t max_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, size, max_size, id);
out:
fdput(f);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);