Re: [PATCH] vfs: Move kernel_read_file() to fs/read_write.c

Mimi Zohar
2019-03-04T16:12:32Z

On Mon, 2019-03-04 at 15:11 +0000, David Howells wrote:
> Move kernel_read_file() to fs/read_write.c and out of fs/exec.c as it's not
> actually used by anything in the execve subsystem.

All files being opened by the kernel should be calling one of these
helper routines.  Has that changed?

Mimi

>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
> ---
>
> fs/exec.c | 106 -------------------------------------------------------
> fs/read_write.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 106 insertions(+), 106 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index fb72d36f7823..cbb1a9cd25ca 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -61,7 +61,6 @@
> #include <linux/pipe_fs_i.h>
> #include <linux/oom.h>
> #include <linux/compat.h>
> -#include <linux/vmalloc.h>
>
> #include <linux/uaccess.h>
> #include <asm/mmu_context.h>
> @@ -892,111 +891,6 @@ 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;
> - 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 (id != READING_FIRMWARE_PREALLOC_BUFFER)
> - *buf = 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;
> - }
> -
> - 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 (id != READING_FIRMWARE_PREALLOC_BUFFER) {
> - 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_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);
> -
> ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
> {
> ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
> diff --git a/fs/read_write.c b/fs/read_write.c
> index ff3c5e6f87cf..555dcaec00ac 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -20,6 +20,7 @@
> #include <linux/compat.h>
> #include <linux/mount.h>
> #include <linux/fs.h>
> +#include <linux/vmalloc.h>
> #include "internal.h"
>
> #include <linux/uaccess.h>
> @@ -1362,6 +1363,111 @@ COMPAT_SYSCALL_DEFINE6(pwritev2, compat_ulong_t, fd,
>
> #endif
>
> +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;
> + 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 (id != READING_FIRMWARE_PREALLOC_BUFFER)
> + *buf = 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;
> + }
> +
> + 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 (id != READING_FIRMWARE_PREALLOC_BUFFER) {
> + 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_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);
> +
> static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
> size_t count, loff_t max)
> {
>