linux/include/linux/kernel_read_file.h
Pasha Tatashin dabba87229 fs/kernel_read_file: allow to read files up-to ssize_t
Patch series "Allow to kexec with initramfs larger than 2G", v2.

Currently, the largest initramfs that is supported by kexec_file_load()
syscall is 2G.

This is because kernel_read_file() returns int, and is limited to INT_MAX
or 2G.

On the other hand, there are kexec based boot loaders (i.e.  u-root), that
may need to boot netboot images that might be larger than 2G.

The first patch changes the return type from int to ssize_t in
kernel_read_file* functions.

The second patch increases the maximum initramfs file size to 4G.

Tested: verified that can kexec_file_load() works with 4G initramfs
on x86_64.


This patch (of 2):

Currently, the maximum file size that is supported is 2G.  This may be too
small in some cases.  For example, kexec_file_load() system call loads
initramfs.  In some netboot cases initramfs can be rather large.

Allow to use up-to ssize_t bytes.  The callers still can limit the maximum
file size via buf_size.

Link: https://lkml.kernel.org/r/20220527025535.3953665-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20220527025535.3953665-2-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-16 19:58:21 -07:00

56 lines
1.6 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_KERNEL_READ_FILE_H
#define _LINUX_KERNEL_READ_FILE_H
#include <linux/file.h>
#include <linux/types.h>
/* This is a list of *what* is being read, not *how* nor *where*. */
#define __kernel_read_file_id(id) \
id(UNKNOWN, unknown) \
id(FIRMWARE, firmware) \
id(MODULE, kernel-module) \
id(KEXEC_IMAGE, kexec-image) \
id(KEXEC_INITRAMFS, kexec-initramfs) \
id(POLICY, security-policy) \
id(X509_CERTIFICATE, x509-certificate) \
id(MAX_ID, )
#define __fid_enumify(ENUM, dummy) READING_ ## ENUM,
#define __fid_stringify(dummy, str) #str,
enum kernel_read_file_id {
__kernel_read_file_id(__fid_enumify)
};
static const char * const kernel_read_file_str[] = {
__kernel_read_file_id(__fid_stringify)
};
static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
{
if ((unsigned int)id >= READING_MAX_ID)
return kernel_read_file_str[READING_UNKNOWN];
return kernel_read_file_str[id];
}
ssize_t kernel_read_file(struct file *file, loff_t offset,
void **buf, size_t buf_size,
size_t *file_size,
enum kernel_read_file_id id);
ssize_t kernel_read_file_from_path(const char *path, loff_t offset,
void **buf, size_t buf_size,
size_t *file_size,
enum kernel_read_file_id id);
ssize_t kernel_read_file_from_path_initns(const char *path, loff_t offset,
void **buf, size_t buf_size,
size_t *file_size,
enum kernel_read_file_id id);
ssize_t kernel_read_file_from_fd(int fd, loff_t offset,
void **buf, size_t buf_size,
size_t *file_size,
enum kernel_read_file_id id);
#endif /* _LINUX_KERNEL_READ_FILE_H */