linux-stable.git/fs/fuse/dev.c, branch v6.11

Merge tag 'fuse-fixes-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2024-09-03T19:32:00+00:00

Pull fuse fixes from Miklos Szeredi:

 - Fix EIO if splice and page stealing are enabled on the fuse device

 - Disable problematic combination of passthrough and writeback-cache

 - Other bug fixes found by code review

* tag 'fuse-fixes-6.11-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: disable the combination of passthrough and writeback cache
  fuse: update stats for pages in dropped aux writeback list
  fuse: clear PG_uptodate when using a stolen page
  fuse: fix memory leak in fuse_create_open
  fuse: check aborted connection before adding requests to pending list for resending
  fuse: use unsigned type for getxattr/listxattr size truncation

fuse: clear PG_uptodate when using a stolen page

2024-08-28T16:10:29+00:00

Originally when a stolen page was inserted into fuse's page cache by
fuse_try_move_page(), it would be marked uptodate.  Then
fuse_readpages_end() would call SetPageUptodate() again on the already
uptodate page.

Commit 413e8f014c8b ("fuse: Convert fuse_readpages_end() to use
folio_end_read()") changed that by replacing the SetPageUptodate() +
unlock_page() combination with folio_end_read(), which does mostly the
same, except it sets the uptodate flag with an xor operation, which in the
above scenario resulted in the uptodate flag being cleared, which in turn
resulted in EIO being returned on the read.

Fix by clearing PG_uptodate instead of setting it in fuse_try_move_page(),
conforming to the expectation of folio_end_read().

Reported-by: Jürg Billeter 
Debugged-by: Matthew Wilcox 
Fixes: 413e8f014c8b ("fuse: Convert fuse_readpages_end() to use folio_end_read()")
Cc:  # v6.10
Signed-off-by: Miklos Szeredi

fuse: check aborted connection before adding requests to pending list for resending

2024-08-28T16:10:29+00:00

There is a race condition where inflight requests will not be aborted if
they are in the middle of being re-sent when the connection is aborted.

If fuse_resend has already moved all the requests in the fpq->processing
lists to its private queue ("to_queue") and then the connection starts
and finishes aborting, these requests will be added to the pending queue
and remain on it indefinitely.

Fixes: 760eac73f9f6 ("fuse: Introduce a new notification type for resend pending requests")
Signed-off-by: Joanne Koong 
Reviewed-by: Josef Bacik 
Reviewed-by: Jingbo Xu 
Cc:  # v6.9
Signed-off-by: Miklos Szeredi

fuse: Initialize beyond-EOF page contents before setting uptodate

2024-08-18T15:45:39+00:00

fuse_notify_store(), unlike fuse_do_readpage(), does not enable page
zeroing (because it can be used to change partial page contents).

So fuse_notify_store() must be more careful to fully initialize page
contents (including parts of the page that are beyond end-of-file)
before marking the page uptodate.

The current code can leave beyond-EOF page contents uninitialized, which
makes these uninitialized page contents visible to userspace via mmap().

This is an information leak, but only affects systems which do not
enable init-on-alloc (via CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y or the
corresponding kernel command line parameter).

Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=2574
Cc: stable@kernel.org
Fixes: a1d75f258230 ("fuse: add store request")
Signed-off-by: Jann Horn 
Signed-off-by: Linus Torvalds

fuse: clear FR_SENT when re-adding requests into pending list

2024-05-10T09:10:39+00:00

The following warning was reported by lee bruce:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 8264 at fs/fuse/dev.c:300
  fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300
  Modules linked in:
  CPU: 0 PID: 8264 Comm: ab2 Not tainted 6.9.0-rc7
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
  RIP: 0010:fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300
  ......
  Call Trace:
  
  fuse_dev_do_read.constprop.0+0xd36/0x1dd0 fs/fuse/dev.c:1334
  fuse_dev_read+0x166/0x200 fs/fuse/dev.c:1367
  call_read_iter include/linux/fs.h:2104 [inline]
  new_sync_read fs/read_write.c:395 [inline]
  vfs_read+0x85b/0xba0 fs/read_write.c:476
  ksys_read+0x12f/0x260 fs/read_write.c:619
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xce/0x260 arch/x86/entry/common.c:83
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
  ......
  

The warning is due to the FUSE_NOTIFY_RESEND notify sent by the write()
syscall in the reproducer program and it happens as follows:

(1) calls fuse_dev_read() to read the INIT request
The read succeeds. During the read, bit FR_SENT will be set on the
request.
(2) calls fuse_dev_write() to send an USE_NOTIFY_RESEND notify
The resend notify will resend all processing requests, so the INIT
request is moved from processing list to pending list again.
(3) calls fuse_dev_read() with an invalid output address
fuse_dev_read() will try to copy the same INIT request to the output
address, but it will fail due to the invalid address, so the INIT
request is ended and triggers the warning in fuse_request_end().

Fix it by clearing FR_SENT when re-adding requests into pending list.

Acked-by: Miklos Szeredi 
Reported-by: xingwei lee 
Reported-by: yue sun 
Closes: https://lore.kernel.org/linux-fsdevel/58f13e47-4765-fce4-daf4-dffcc5ae2330@huaweicloud.com/T/#m091614e5ea2af403b259e7cea6a49e51b9ee07a7
Fixes: 760eac73f9f6 ("fuse: Introduce a new notification type for resend pending requests")
Signed-off-by: Hou Tao 
Signed-off-by: Miklos Szeredi

fuse: set FR_PENDING atomically in fuse_resend()

2024-05-10T09:10:12+00:00

When fuse_resend() moves the requests from processing lists to pending
list, it uses __set_bit() to set FR_PENDING bit in req->flags.

Using __set_bit() is not safe, because other functions may update
req->flags concurrently (e.g., request_wait_answer() may call
set_bit(FR_INTERRUPTED, &flags)).

Fix it by using set_bit() instead.

Fixes: 760eac73f9f6 ("fuse: Introduce a new notification type for resend pending requests")
Signed-off-by: Hou Tao 
Signed-off-by: Miklos Szeredi

fuse: Use the high bit of request ID for indicating resend requests

2024-03-06T08:56:35+00:00

Some FUSE daemons want to know if the received request is a resend
request. The high bit of the fuse request ID is utilized for indicating
this, enabling the receiver to perform appropriate handling.

The init flag "FUSE_HAS_RESEND" is added to indicate this feature.

Signed-off-by: Zhao Chen 
Signed-off-by: Miklos Szeredi

fuse: Introduce a new notification type for resend pending requests

2024-03-06T08:56:34+00:00

When a FUSE daemon panics and failover, we aim to minimize the impact on
applications by reusing the existing FUSE connection. During this process,
another daemon is employed to preserve the FUSE connection's file
descriptor. The new started FUSE Daemon will takeover the fd and continue
to provide service.

However, it is possible for some inflight requests to be lost and never
returned. As a result, applications awaiting replies would become stuck
forever. To address this, we can resend these pending requests to the
new started FUSE daemon.

This patch introduces a new notification type "FUSE_NOTIFY_RESEND", which
can trigger resending of the pending requests, ensuring they are properly
processed again.

Signed-off-by: Zhao Chen 
Signed-off-by: Miklos Szeredi

fuse: implement ioctls to manage backing files

2024-03-05T12:40:36+00:00

FUSE server calls the FUSE_DEV_IOC_BACKING_OPEN ioctl with a backing file
descriptor.  If the call succeeds, a backing file identifier is returned.

A later change will be using this backing file id in a reply to OPEN
request with the flag FOPEN_PASSTHROUGH to setup passthrough of file
operations on the open FUSE file to the backing file.

The FUSE server should call FUSE_DEV_IOC_BACKING_CLOSE ioctl to close the
backing file by its id.

This can be done at any time, but if an open reply with FOPEN_PASSTHROUGH
flag is still in progress, the open may fail if the backing file is
closed before the fuse file was opened.

Setting up backing files requires a server with CAP_SYS_ADMIN privileges.
For the backing file to be successfully setup, the backing file must
implement both read_iter and write_iter file operations.

The limitation on the level of filesystem stacking allowed for the
backing file is enforced before setting up the backing file.

Signed-off-by: Alessio Balsini 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

fuse: factor out helper for FUSE_DEV_IOC_CLONE

2024-02-23T16:36:32+00:00

In preparation to adding more fuse dev ioctls.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi