configfs: restore the kernel v5.13 text attribute write behavior

Instead of appending new text attribute data at the offset specified by the
write() system call, only pass the newly written data to the .store()
callback.

Reported-by: Bodo Stroesser <bostroesser@gmail.com>
Tested-by: Bodo Stroesser <bostroesser@gmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: fix the read and write iterators

Commit 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter
methods") changed the simple_read_from_buffer() calls into copy_to_iter()
calls and the simple_write_to_buffer() calls into copy_from_iter() calls.
The simple*buffer() methods update the file offset (*ppos) but the read
and write iterators not yet. Make the read and write iterators update the
file offset (iocb->ki_pos).

This patch has been tested as follows:

# modprobe target_core_user
# dd if=/sys/kernel/config/target/dbroot bs=1
/var/target
12+0 records in
12+0 records out
12 bytes copied, 9.5539e-05 s, 126 kB/s

# cd /sys/kernel/config/acpi/table
# mkdir test
# cd test
# dmesg -c >/dev/null; printf 'SSDT\x8\0\0\0abcdefghijklmnopqrstuvwxyz' | dd of=aml bs=1; dmesg -c
34+0 records in
34+0 records out
34 bytes copied, 0.010627 s, 3.2 kB/s
[ 261.056551] ACPI configfs: invalid table length

Reported-by: Yanko Kaneti <yaneti@declera.com>
Cc: Yanko Kaneti <yaneti@declera.com>
Fixes: 7fe1e79b59ba ("configfs: implement the .read_iter and .write_iter methods")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: simplify configfs_release_bin_file

Remove the clearing of various fields just before freeing the
buffer structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: fix memleak in configfs_release_bin_file

When reading binary attributes in progress, buffer->bin_buffer is setup in
configfs_read_bin_file() but never freed.

Fixes: 03607ace807b4 ("configfs: implement binary attributes")
Signed-off-by: Chung-Chiang Cheng <cccheng@synology.com>
[hch: move the vfree rather than duplicating it]
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: implement the .read_iter and .write_iter methods

Configfs is one of the few filesystems that does not yet support the
.read_iter and .write_iter callbacks. This patch adds support for these
methods in configfs.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: split out a separate fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: drop pointless kerneldoc comments

file.c has a bunch of kerneldoc comments for static functions that do not
document any API but just list what is done. Drop them.

Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: fix the kerneldoc comment for configfs_create_bin_file

Mention the correct argument name.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>

treewide: remove editor modelines and cruft

The section "19) Editor modelines and other cruft" in
Documentation/process/coding-style.rst clearly says, "Do not include any
of these in source files."

I recently receive a patch to explicitly add a new one.

Let's do treewide cleanups, otherwise some people follow the existing code
and attempt to upstream their favoriate editor setups.

It is even nicer if scripts/checkpatch.pl can check it.

If we like to impose coding style in an editor-independent manner, I think
editorconfig (patch [1]) is a saner solution.

[1] https://lore.kernel.org/lkml/20200703073143.423557-1-danny@kdrag0n.dev/

Link: https://lkml.kernel.org/r/20210324054457.1477489-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org> [auxdisplay]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

configfs: fix a use-after-free in __configfs_open_file

Commit b0841eefd969 ("configfs: provide exclusion between IO and removals")
uses ->frag_dead to mark the fragment state, thus no bothering with extra
refcount on config_item when opening a file. The configfs_get_config_item
was removed in __configfs_open_file, but not with config_item_put. So the
refcount on config_item will lost its balance, causing use-after-free
issues in some occasions like this:

Test:
1. Mount configfs on /config with read-only items:
drwxrwx--- 289 root root 0 2021-04-01 11:55 /config
drwxr-xr-x 2 root root 0 2021-04-01 11:54 /config/a
--w--w--w- 1 root root 4096 2021-04-01 11:53 /config/a/1.txt
......

2. Then run:
for file in /config
do
echo $file
grep -R 'key' $file
done

3. __configfs_open_file will be called in parallel, the first one
got called will do:
if (file->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO))
goto out_put_module;
config_item_put(buffer->item);
kref_put()
package_details_release()
kfree()

the other one will run into use-after-free issues like this:
BUG: KASAN: use-after-free in __configfs_open_file+0x1bc/0x3b0
Read of size 8 at addr fffffff155f02480 by task grep/13096
CPU: 0 PID: 13096 Comm: grep VIP: 00 Tainted: G W 4.14.116-kasan #1
TGID: 13096 Comm: grep
Call trace:
dump_stack+0x118/0x160
kasan_report+0x22c/0x294
__asan_load8+0x80/0x88
__configfs_open_file+0x1bc/0x3b0
configfs_open_file+0x28/0x34
do_dentry_open+0x2cc/0x5c0
vfs_open+0x80/0xe0
path_openat+0xd8c/0x2988
do_filp_open+0x1c4/0x2fc
do_sys_open+0x23c/0x404
SyS_openat+0x38/0x48

Allocated by task 2138:
kasan_kmalloc+0xe0/0x1ac
kmem_cache_alloc_trace+0x334/0x394
packages_make_item+0x4c/0x180
configfs_mkdir+0x358/0x740
vfs_mkdir2+0x1bc/0x2e8
SyS_mkdirat+0x154/0x23c
el0_svc_naked+0x34/0x38

Freed by task 13096:
kasan_slab_free+0xb8/0x194
kfree+0x13c/0x910
package_details_release+0x524/0x56c
kref_put+0xc4/0x104
config_item_put+0x24/0x34
__configfs_open_file+0x35c/0x3b0
configfs_open_file+0x28/0x34
do_dentry_open+0x2cc/0x5c0
vfs_open+0x80/0xe0
path_openat+0xd8c/0x2988
do_filp_open+0x1c4/0x2fc
do_sys_open+0x23c/0x404
SyS_openat+0x38/0x48
el0_svc_naked+0x34/0x38

To fix this issue, remove the config_item_put in
__configfs_open_file to balance the refcount of config_item.

Fixes: b0841eefd969 ("configfs: provide exclusion between IO and removals")
Signed-off-by: Daiyue Zhang <zhangdaiyue1@huawei.com>
Signed-off-by: Yi Chen <chenyi77@huawei.com>
Signed-off-by: Ge Qiu <qiuge@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

fs: configfs: delete repeated words in comments

Drop duplicated words {the, that} in comments.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20200811021826.25032-1-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

configfs: provide exclusion between IO and removals

Make sure that attribute methods are not called after the item
has been removed from the tree. To do so, we
* at the point of no return in removals, grab ->frag_sem
exclusive and mark the fragment dead.
* call the methods of attributes with ->frag_sem taken
shared and only after having verified that the fragment is still
alive.

The main benefit is for method instances - they are
guaranteed that the objects they are accessing *and* all ancestors
are still there. Another win is that we don't need to bother
with extra refcount on config_item when opening a file -
the item will be alive for as long as it stays in the tree, and
we won't touch it/attributes/any associated data after it's
been removed from the tree.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: new object reprsenting tree fragments

Refcounted, hangs of configfs_dirent, created by operations that add
fragments to configfs tree (mkdir and configfs_register_{subsystem,group}).
Will be used in the next commit to provide exclusion between fragment
removal and ->show/->store calls.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: stash the data we need into configfs_buffer at open time

simplifies the ->read()/->write()/->release() instances nicely

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 145

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 021110 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 84 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190524100844.756442981@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

configfs: Fix bool initialization/comparison

Bool initializations should use true and false. Bool tests don't need
comparisons.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Replace <asm/uaccess.h> with <linux/uaccess.h> globally

This was entirely automated, using the script by Al:

PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

configfs: Return -EFBIG from configfs_write_bin_file.

The check for writing more than cb_max_size bytes does not 'goto out' so
it is a no-op which allows users to vmalloc an arbitrary amount.

Fixes: 03607ace807b ("configfs: implement binary attributes")
Cc: stable@kernel.org
Signed-off-by: Phil Turnbull <phil.turnbull@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: don't set buffer_needs_fill to zero if show() returns error

A confgifs attribute's show() callback is called once the first time
the user attempts to read from it. If it returns an error, that
error is returned to the user. However, the open file's
buffer_needs_fill is still set to zero and consecutive read() calls
will find an empty buffer that doesn't need filling and return 0 to
the user. This could give the user the wrong impression that the
attribute was read successfully.

Fix this by not setting buffer_needs_fill if show() returns an error,
making consecutive read() calls call show() again and either get an
error again or get data.

Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: Remove ppos increment in configfs_write_bin_file

The simple_write_to_buffer() already increments the @ppos on success,
see fs/libfs.c simple_write_to_buffer() comment:

"
On success, the number of bytes written is returned and the offset @ppos
advanced by this number, or negative value is returned on error.
"

If the configfs_write_bin_file() is invoked with @count smaller than the
total length of the written binary file, it will be invoked multiple times.
Since configfs_write_bin_file() increments @ppos on success, after calling
simple_write_to_buffer(), the @ppos is incremented twice.

Subsequent invocation of configfs_write_bin_file() will result in the next
piece of data being written to the offset twice as long as the length of
the previous write, thus creating buffer with "holes" in it.

The simple testcase using DTO follows:
$ mkdir /sys/kernel/config/device-tree/overlays/1
$ dd bs=1 if=foo.dtbo of=/sys/kernel/config/device-tree/overlays/1/dtbo
Without this patch, the testcase will result in twice as big buffer in the
kernel, which is then passed to the cfs_overlay_item_dtbo_write() .

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>

wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

configfs: implement binary attributes

ConfigFS lacked binary attributes up until now. This patch
introduces support for binary attributes in a somewhat similar
manner of sysfs binary attributes albeit with changes that
fit the configfs usage model.

Problems that configfs binary attributes fix are everything that
requires a binary blob as part of the configuration of a resource,
such as bitstream loading for FPGAs, DTBs for dynamically created
devices etc.

Look at Documentation/filesystems/configfs/configfs.txt for internals
and howto use them.

This patch is against linux-next as of today that contains
Christoph's configfs rework.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[hch: folded a fix from Geert Uytterhoeven <geert+renesas@glider.be>]
[hch: a few tiny updates based on review feedback]
Signed-off-by: Christoph Hellwig <hch@lst.de>

configfs: remove old API

Remove the old show_attribute and store_attribute methods and update
the documentation. Also replace the two C samples with a single new
one in the proper samples directory where people expect to find it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

configfs: add show and store methods to struct configfs_attribute

Add methods to struct configfs_attribute to directly show and store
attributes without adding boilerplate code to every user. In addition
to the methods this also adds 3 helper macros to define read/write,
read-only and write-only attributes with a single line of code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

VFS: normal filesystems (and lustre): d_inode() annotations

that's the bulk of filesystem drivers dealing with inodes of their own

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

configfs_add_file: fold into its sole caller

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

configfs: use capped length for ->store_attribute()

The difference between "count" and "len" is that "len" is capped at
4095. Changing it like this makes it match how sysfs_write_file() is
implemented.

This is a static analysis patch. I haven't found any store_attribute()
functions where this change makes a difference.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs: replace remaining __FUNCTION__ occurrences

__FUNCTION__ is gcc-specific, use __func__

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

configfs: file.c fix possible recursive locking

configfs_register_subsystem() with default_groups triggers recursive locking.
it seems that mutex_lock_nested is needed.

=============================================
[ INFO: possible recursive locking detected ]
2.6.24-rc6 #145
---------------------------------------------
swapper/1 is trying to acquire lock:
(&sb->s_type->i_mutex_key#3){--..}, at: [<c40c9a9e>] configfs_add_file+0x2e/0x70

but task is already holding lock:
(&sb->s_type->i_mutex_key#3){--..}, at: [<c40ca985>] configfs_register_subsystem+0x55/0x130

other info that might help us debug this:
1 lock held by swapper/1:
#0: (&sb->s_type->i_mutex_key#3){--..}, at: [<c40ca985>] configfs_register_subsystem+0x55/0x130

stack backtrace:
Pid: 1, comm: swapper Not tainted 2.6.24-rc6 #145
[<c40053ba>] show_trace_log_lvl+0x1a/0x30
[<c4005e82>] show_trace+0x12/0x20
[<c400687e>] dump_stack+0x6e/0x80
[<c404ec72>] __lock_acquire+0xe62/0x1120
[<c404efb2>] lock_acquire+0x82/0xa0
[<c43fda88>] mutex_lock_nested+0x98/0x2e0
[<c40c9a9e>] configfs_add_file+0x2e/0x70
[<c40c9b0c>] configfs_create_file+0x2c/0x40
[<c40ca639>] configfs_attach_item+0x139/0x220
[<c40ca734>] configfs_attach_group+0x14/0x140
[<c40ca7e9>] configfs_attach_group+0xc9/0x140
[<c40ca9f6>] configfs_register_subsystem+0xc6/0x130
[<c45c8186>] init_netconsole+0x2b6/0x300
[<c45a75f2>] kernel_init+0x142/0x320
[<c4004fb3>] kernel_thread_helper+0x7/0x14
=======================

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

[PATCH] configsfs buffer: use mutex

Seems copied from sysfs, but I don't see a reason here nor there to use
a semaphore instead of a mutex. Convert.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

configfs: consistent attribute size

The attribute store/show code currently limits attributes at PAGE_SIZE.
This code comes from sysfs, where it still works that way.

However, PAGE_SIZE is not constant. A 16k attribute string works on
ia64 but not on x86. Really a subsystem shouldn't allow different
attribute sizes based on platform.

As such, limit all simple attributes to 4k. This works on all
platforms, and is consistent with all current code.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

use simple_read_from_buffer() in fs/

Cleanup using simple_read_from_buffer() in binfmt_misc, configfs, and sysfs.

Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

configfs: Zero terminate data in configfs attribute writes.

Attributes in configfs are text files. As such, most handlers expect to be
able to call functions like simple_strtoul() without checking the bounds
of the buffer. Change the call to zero terminate the buffer before calling
the client's ->store() method. This does reduce the attribute size from
PAGE_SIZE to PAGE_SIZE-1.

Also, change get_zeroed_page() to alloc_page(), as we are handling the
termination.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

[PATCH] configfs: change uses of f_{dentry, vfsmnt} to use f_path

Change all the uses of f_{dentry,vfsmnt} to f_path.{dentry,mnt} in the
configfs filesystem.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

configfs: handle kzalloc() failure in check_perm()

check_perm() does not drop the reference to the module when kzalloc()
failure occurs.

Signed-Off-By: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

[PATCH] pr_debug: configfs: use size_t length modifier in pr_debug format argument

configfs: use size_t length modifier in pr_debug format argument

Signed-off-by: Zach Brown <zach.brown@oracle.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] fs: Conversions from kmalloc+memset to k(z|c)alloc

Conversions from kmalloc+memset to kzalloc.

Signed-off-by: Panagiotis Issaris <takis@issaris.org>
Jffs2-bit-acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Make most file operations structs in fs/ const

This is a conversion to make the various file_operations structs in fs/
const. Basically a regexp job, with a few manual fixups

The goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

configfs: Add permission and ownership to configfs objects.

configfs always made item and attribute ownership root.root and
permissions based on a umask of 022. Add ->setattr() to allow
chown(2)/chmod(2), and persist the changes for the lifetime of the
items and attributes.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

[PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_sem

This patch converts the inode semaphore to a mutex. I have tested it on
XFS and compiled as much as one can consider on an ia64. Anyway your
luck with it might be different.

Modified-by: Ingo Molnar <mingo@elte.hu>

(finished the conversion)

Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH] configfs: User-driven configuration filesystem

Configfs, a file system for userspace-driven kernel object configuration.
The OCFS2 stack makes extensive use of this for propagation of cluster
configuration information into kernel.

Signed-off-by: Joel Becker <joel.becker@oracle.com>