The patch titled
Subject: fs/kernel_read_file: allow to read files up-to ssize_t
has been added to the -mm mm-nonmm-unstable branch. Its filename is
fs-kernel_read_file-allow-to-read-files-up-to-ssize_t.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-kernel_read_file-allow-to-read-files-up-to-ssize_t.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: fs/kernel_read_file: allow to read files up-to ssize_t
Date: Fri, 27 May 2022 02:55:34 +0000
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@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20220527025535.3953665-2-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/kernel_read_file.c | 38 ++++++++++++++---------------
include/linux/kernel_read_file.h | 32 ++++++++++++------------
include/linux/limits.h | 1
3 files changed, 36 insertions(+), 35 deletions(-)
--- a/fs/kernel_read_file.c~fs-kernel_read_file-allow-to-read-files-up-to-ssize_t
+++ a/fs/kernel_read_file.c
@@ -29,15 +29,15 @@
* change between calls to kernel_read_file().
*
* Returns number of bytes read (no single read will be bigger
- * than INT_MAX), or negative on error.
+ * than SSIZE_MAX), or negative on error.
*
*/
-int 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(struct file *file, loff_t offset, void **buf,
+ size_t buf_size, size_t *file_size,
+ enum kernel_read_file_id id)
{
loff_t i_size, pos;
- size_t copied;
+ ssize_t copied;
void *allocated = NULL;
bool whole_file;
int ret;
@@ -58,7 +58,7 @@ int kernel_read_file(struct file *file,
goto out;
}
/* The file is too big for sane activities. */
- if (i_size > INT_MAX) {
+ if (i_size > SSIZE_MAX) {
ret = -EFBIG;
goto out;
}
@@ -124,12 +124,12 @@ out:
}
EXPORT_SYMBOL_GPL(kernel_read_file);
-int 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(const char *path, loff_t offset, void **buf,
+ size_t buf_size, size_t *file_size,
+ enum kernel_read_file_id id)
{
struct file *file;
- int ret;
+ ssize_t ret;
if (!path || !*path)
return -EINVAL;
@@ -144,14 +144,14 @@ int kernel_read_file_from_path(const cha
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
-int 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_path_initns(const char *path, loff_t offset,
+ void **buf, size_t buf_size,
+ size_t *file_size,
+ enum kernel_read_file_id id)
{
struct file *file;
struct path root;
- int ret;
+ ssize_t ret;
if (!path || !*path)
return -EINVAL;
@@ -171,12 +171,12 @@ int kernel_read_file_from_path_initns(co
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
-int 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)
+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)
{
struct fd f = fdget(fd);
- int ret = -EBADF;
+ ssize_t ret = -EBADF;
if (!f.file || !(f.file->f_mode & FMODE_READ))
goto out;
--- a/include/linux/kernel_read_file.h~fs-kernel_read_file-allow-to-read-files-up-to-ssize_t
+++ a/include/linux/kernel_read_file.h
@@ -35,21 +35,21 @@ static inline const char *kernel_read_fi
return kernel_read_file_str[id];
}
-int 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);
-int 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);
-int 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);
-int 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);
+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 */
--- a/include/linux/limits.h~fs-kernel_read_file-allow-to-read-files-up-to-ssize_t
+++ a/include/linux/limits.h
@@ -7,6 +7,7 @@
#include <vdso/limits.h>
#define SIZE_MAX (~(size_t)0)
+#define SSIZE_MAX ((ssize_t)(SIZE_MAX >> 1))
#define PHYS_ADDR_MAX (~(phys_addr_t)0)
#define U8_MAX ((u8)~0U)
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
fs-kernel_read_file-allow-to-read-files-up-to-ssize_t.patch
kexec_file-increase-maximum-file-size-to-4g.patch
