linux-stable.git/fs/fuse, branch v5.13.4 Linux kernel stable tree fuse: fix illegal access to inode with reused nodeid 2021-07-20T14:00:24+00:00 Amir Goldstein amir73il@gmail.com 2021-06-21T11:03:53+00:00 c09a4ad6251f9354df0915ac5b8f22c7b9d6bc11 [ Upstream commit 15db16837a35d8007cb8563358787412213db25e ] Server responds to LOOKUP and other ops (READDIRPLUS/CREATE/MKNOD/...) with ourarg containing nodeid and generation. If a fuse inode is found in inode cache with the same nodeid but different generation, the existing fuse inode should be unhashed and marked "bad" and a new inode with the new generation should be hashed instead. This can happen, for example, with passhrough fuse filesystem that returns the real filesystem ino/generation on lookup and where real inode numbers can get recycled due to real files being unlinked not via the fuse passthrough filesystem. With current code, this situation will not be detected and an old fuse dentry that used to point to an older generation real inode, can be used to access a completely new inode, which should be accessed only via the new dentry. Note that because the FORGET message carries the nodeid w/o generation, the server should wait to get FORGET counts for the nlookup counts of the old and reused inodes combined, before it can free the resources associated to that nodeid. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 15db16837a35d8007cb8563358787412213db25e ]

Server responds to LOOKUP and other ops (READDIRPLUS/CREATE/MKNOD/...)
with ourarg containing nodeid and generation.

If a fuse inode is found in inode cache with the same nodeid but different
generation, the existing fuse inode should be unhashed and marked "bad" and
a new inode with the new generation should be hashed instead.

This can happen, for example, with passhrough fuse filesystem that returns
the real filesystem ino/generation on lookup and where real inode numbers
can get recycled due to real files being unlinked not via the fuse
passthrough filesystem.

With current code, this situation will not be detected and an old fuse
dentry that used to point to an older generation real inode, can be used to
access a completely new inode, which should be accessed only via the new
dentry.

Note that because the FORGET message carries the nodeid w/o generation, the
server should wait to get FORGET counts for the nlookup counts of the old
and reused inodes combined, before it can free the resources associated to
that nodeid.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
virtiofs: propagate sync() to file server 2021-07-20T14:00:24+00:00 Greg Kurz groug@kaod.org 2021-05-20T15:46:54+00:00 6ba041fc3c441e0cf4762f4baf0166e8d34f6802 [ Upstream commit 2d82ab251ef0f6e7716279b04e9b5a01a86ca530 ] Even if POSIX doesn't mandate it, linux users legitimately expect sync() to flush all data and metadata to physical storage when it is located on the same system. This isn't happening with virtiofs though: sync() inside the guest returns right away even though data still needs to be flushed from the host page cache. This is easily demonstrated by doing the following in the guest: $ dd if=/dev/zero of=/mnt/foo bs=1M count=5K ; strace -T -e sync sync 5120+0 records in 5120+0 records out 5368709120 bytes (5.4 GB, 5.0 GiB) copied, 5.22224 s, 1.0 GB/s sync() = 0 <0.024068> and start the following in the host when the 'dd' command completes in the guest: $ strace -T -e fsync /usr/bin/sync virtiofs/foo fsync(3) = 0 <10.371640> There are no good reasons not to honor the expected behavior of sync() actually: it gives an unrealistic impression that virtiofs is super fast and that data has safely landed on HW, which isn't the case obviously. Implement a ->sync_fs() superblock operation that sends a new FUSE_SYNCFS request type for this purpose. Provision a 64-bit placeholder for possible future extensions. Since the file server cannot handle the wait == 0 case, we skip it to avoid a gratuitous roundtrip. Note that this is per-superblock: a FUSE_SYNCFS is send for the root mount and for each submount. Like with FUSE_FSYNC and FUSE_FSYNCDIR, lack of support for FUSE_SYNCFS in the file server is treated as permanent success. This ensures compatibility with older file servers: the client will get the current behavior of sync() not being propagated to the file server. Note that such an operation allows the file server to DoS sync(). Since a typical FUSE file server is an untrusted piece of software running in userspace, this is disabled by default. Only enable it with virtiofs for now since virtiofsd is supposedly trusted by the guest kernel. Reported-by: Robert Krawitz <rlk@redhat.com> Signed-off-by: Greg Kurz <groug@kaod.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2d82ab251ef0f6e7716279b04e9b5a01a86ca530 ]

Even if POSIX doesn't mandate it, linux users legitimately expect sync() to
flush all data and metadata to physical storage when it is located on the
same system.  This isn't happening with virtiofs though: sync() inside the
guest returns right away even though data still needs to be flushed from
the host page cache.

This is easily demonstrated by doing the following in the guest:

$ dd if=/dev/zero of=/mnt/foo bs=1M count=5K ; strace -T -e sync sync
5120+0 records in
5120+0 records out
5368709120 bytes (5.4 GB, 5.0 GiB) copied, 5.22224 s, 1.0 GB/s
sync()                                  = 0 <0.024068>

and start the following in the host when the 'dd' command completes
in the guest:

$ strace -T -e fsync /usr/bin/sync virtiofs/foo
fsync(3)                                = 0 <10.371640>

There are no good reasons not to honor the expected behavior of sync()
actually: it gives an unrealistic impression that virtiofs is super fast
and that data has safely landed on HW, which isn't the case obviously.

Implement a ->sync_fs() superblock operation that sends a new FUSE_SYNCFS
request type for this purpose.  Provision a 64-bit placeholder for possible
future extensions.  Since the file server cannot handle the wait == 0 case,
we skip it to avoid a gratuitous roundtrip.  Note that this is
per-superblock: a FUSE_SYNCFS is send for the root mount and for each
submount.

Like with FUSE_FSYNC and FUSE_FSYNCDIR, lack of support for FUSE_SYNCFS in
the file server is treated as permanent success.  This ensures
compatibility with older file servers: the client will get the current
behavior of sync() not being propagated to the file server.

Note that such an operation allows the file server to DoS sync().  Since a
typical FUSE file server is an untrusted piece of software running in
userspace, this is disabled by default.  Only enable it with virtiofs for
now since virtiofsd is supposedly trusted by the guest kernel.

Reported-by: Robert Krawitz <rlk@redhat.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
fuse: reject internal errno 2021-07-14T15:06:18+00:00 Miklos Szeredi mszeredi@redhat.com 2021-06-22T07:15:35+00:00 0c1678f223daf89364283d4fa1b362b404d7b056 commit 49221cf86d18bb66fe95d3338cb33bd4b9880ca5 upstream. Don't allow userspace to report errors that could be kernel-internal. Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Fixes: 334f485df85a ("[PATCH] FUSE - device functions") Cc: <stable@vger.kernel.org> # v2.6.14 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 49221cf86d18bb66fe95d3338cb33bd4b9880ca5 upstream.

Don't allow userspace to report errors that could be kernel-internal.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Fixes: 334f485df85a ("[PATCH] FUSE - device functions")
Cc: <stable@vger.kernel.org> # v2.6.14
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fuse: check connected before queueing on fpq->io 2021-07-14T15:06:18+00:00 Miklos Szeredi mszeredi@redhat.com 2021-06-22T07:15:35+00:00 2644fd6588e5951012cd4fc7fe016ea8c7157eff commit 80ef08670d4c28a06a3de954bd350368780bcfef upstream. A request could end up on the fpq->io list after fuse_abort_conn() has reset fpq->connected and aborted requests on that list: Thread-1 Thread-2 ======== ======== ->fuse_simple_request() ->shutdown ->__fuse_request_send() ->queue_request() ->fuse_abort_conn() ->fuse_dev_do_read() ->acquire(fpq->lock) ->wait_for(fpq->lock) ->set err to all req's in fpq->io ->release(fpq->lock) ->acquire(fpq->lock) ->add req to fpq->io After the userspace copy is done the request will be ended, but req->out.h.error will remain uninitialized. Also the copy might block despite being already aborted. Fix both issues by not allowing the request to be queued on the fpq->io list after fuse_abort_conn() has processed this list. Reported-by: Pradeep P V K <pragalla@codeaurora.org> Fixes: fd22d62ed0c3 ("fuse: no fc->lock for iqueue parts") Cc: <stable@vger.kernel.org> # v4.2 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 80ef08670d4c28a06a3de954bd350368780bcfef upstream.

A request could end up on the fpq->io list after fuse_abort_conn() has
reset fpq->connected and aborted requests on that list:

Thread-1			  Thread-2
========			  ========
->fuse_simple_request()           ->shutdown
  ->__fuse_request_send()
    ->queue_request()		->fuse_abort_conn()
->fuse_dev_do_read()                ->acquire(fpq->lock)
  ->wait_for(fpq->lock) 	  ->set err to all req's in fpq->io
				  ->release(fpq->lock)
  ->acquire(fpq->lock)
  ->add req to fpq->io

After the userspace copy is done the request will be ended, but
req->out.h.error will remain uninitialized.  Also the copy might block
despite being already aborted.

Fix both issues by not allowing the request to be queued on the fpq->io
list after fuse_abort_conn() has processed this list.

Reported-by: Pradeep P V K <pragalla@codeaurora.org>
Fixes: fd22d62ed0c3 ("fuse: no fc->lock for iqueue parts")
Cc: <stable@vger.kernel.org> # v4.2
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fuse: ignore PG_workingset after stealing 2021-07-14T15:06:18+00:00 Miklos Szeredi mszeredi@redhat.com 2021-06-18T19:16:42+00:00 76d97f2f3b028974f681f32884780f45e09d0d56 commit b89ecd60d38ec042d63bdb376c722a16f92bcb88 upstream. Fix the "fuse: trying to steal weird page" warning. Description from Johannes Weiner: "Think of it as similar to PG_active. It's just another usage/heat indicator of file and anon pages on the reclaim LRU that, unlike PG_active, persists across deactivation and even reclaim (we store it in the page cache / swapper cache tree until the page refaults). So if fuse accepts pages that can legally have PG_active set, PG_workingset is fine too." Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com> Fixes: 1899ad18c607 ("mm: workingset: tell cache transitions from workingset thrashing") Cc: <stable@vger.kernel.org> # v4.20 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b89ecd60d38ec042d63bdb376c722a16f92bcb88 upstream.

Fix the "fuse: trying to steal weird page" warning.

Description from Johannes Weiner:

  "Think of it as similar to PG_active. It's just another usage/heat
   indicator of file and anon pages on the reclaim LRU that, unlike
   PG_active, persists across deactivation and even reclaim (we store it in
   the page cache / swapper cache tree until the page refaults).

   So if fuse accepts pages that can legally have PG_active set,
   PG_workingset is fine too."

Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Fixes: 1899ad18c607 ("mm: workingset: tell cache transitions from workingset thrashing")
Cc: <stable@vger.kernel.org> # v4.20
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fuse: Fix infinite loop in sget_fc() 2021-07-14T15:06:18+00:00 Greg Kurz groug@kaod.org 2021-06-04T16:11:52+00:00 108adb1a56680e47119d94ae3c1beeae1e5ea9a0 commit e4a9ccdd1c03b3dc58214874399d24331ea0a3ab upstream. We don't set the SB_BORN flag on submounts. This is wrong as these superblocks are then considered as partially constructed or dying in the rest of the code and can break some assumptions. One such case is when you have a virtiofs filesystem with submounts and you try to mount it again : virtio_fs_get_tree() tries to obtain a superblock with sget_fc(). The logic in sget_fc() is to loop until it has either found an existing matching superblock with SB_BORN set or to create a brand new one. It is assumed that a superblock without SB_BORN is transient and the loop is restarted. Forgetting to set SB_BORN on submounts hence causes sget_fc() to retry forever. Setting SB_BORN requires special care, i.e. a write barrier for super_cache_count() which can check SB_BORN without taking any lock. We should call vfs_get_tree() to deal with that but this requires to have a proper ->get_tree() implementation for submounts, which is a bigger piece of work. Go for a simple bug fix in the meatime. Fixes: bf109c64040f ("fuse: implement crossmounts") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Greg Kurz <groug@kaod.org> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e4a9ccdd1c03b3dc58214874399d24331ea0a3ab upstream.

We don't set the SB_BORN flag on submounts. This is wrong as these
superblocks are then considered as partially constructed or dying
in the rest of the code and can break some assumptions.

One such case is when you have a virtiofs filesystem with submounts
and you try to mount it again : virtio_fs_get_tree() tries to obtain
a superblock with sget_fc(). The logic in sget_fc() is to loop until
it has either found an existing matching superblock with SB_BORN set
or to create a brand new one. It is assumed that a superblock without
SB_BORN is transient and the loop is restarted. Forgetting to set
SB_BORN on submounts hence causes sget_fc() to retry forever.

Setting SB_BORN requires special care, i.e. a write barrier for
super_cache_count() which can check SB_BORN without taking any lock.
We should call vfs_get_tree() to deal with that but this requires
to have a proper ->get_tree() implementation for submounts, which
is a bigger piece of work. Go for a simple bug fix in the meatime.

Fixes: bf109c64040f ("fuse: implement crossmounts")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fuse: Fix crash if superblock of submount gets killed early 2021-07-14T15:06:18+00:00 Greg Kurz groug@kaod.org 2021-06-04T16:11:51+00:00 809b077db6b821c17b317da46ce10f7df036adfe commit e3a43f2a95393000778f8f302d48795add2fc4a8 upstream. As soon as fuse_dentry_automount() does up_write(&sb->s_umount), the superblock can theoretically be killed. If this happens before the submount was added to the &fc->mounts list, fuse_mount_remove() later crashes in list_del_init() because it assumes the submount to be already there. Add the submount before dropping sb->s_umount to fix the inconsistency. It is okay to nest fc->killsb under sb->s_umount, we already do this on the ->kill_sb() path. Signed-off-by: Greg Kurz <groug@kaod.org> Fixes: bf109c64040f ("fuse: implement crossmounts") Cc: stable@vger.kernel.org # v5.10+ Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e3a43f2a95393000778f8f302d48795add2fc4a8 upstream.

As soon as fuse_dentry_automount() does up_write(&sb->s_umount), the
superblock can theoretically be killed. If this happens before the
submount was added to the &fc->mounts list, fuse_mount_remove() later
crashes in list_del_init() because it assumes the submount to be
already there.

Add the submount before dropping sb->s_umount to fix the inconsistency.
It is okay to nest fc->killsb under sb->s_umount, we already do this
on the ->kill_sb() path.

Signed-off-by: Greg Kurz <groug@kaod.org>
Fixes: bf109c64040f ("fuse: implement crossmounts")
Cc: stable@vger.kernel.org # v5.10+
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fuse: Fix crash in fuse_dentry_automount() error path 2021-07-14T15:06:18+00:00 Greg Kurz groug@kaod.org 2021-06-04T16:11:50+00:00 7ef44eacefc1180f451009cea60f2ad3a467c153 commit d92d88f0568e97c437eeb79d9c9609bd8277406f upstream. If fuse_fill_super_submount() returns an error, the error path triggers a crash: [ 26.206673] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] [ 26.226362] RIP: 0010:__list_del_entry_valid+0x25/0x90 [...] [ 26.247938] Call Trace: [ 26.248300] fuse_mount_remove+0x2c/0x70 [fuse] [ 26.248892] virtio_kill_sb+0x22/0x160 [virtiofs] [ 26.249487] deactivate_locked_super+0x36/0xa0 [ 26.250077] fuse_dentry_automount+0x178/0x1a0 [fuse] The crash happens because fuse_mount_remove() assumes that the FUSE mount was already added to list under the FUSE connection, but this only done after fuse_fill_super_submount() has returned success. This means that until fuse_fill_super_submount() has returned success, the FUSE mount isn't actually owned by the superblock. We should thus reclaim ownership by clearing sb->s_fs_info, which will skip the call to fuse_mount_remove(), and perform rollback, like virtio_fs_get_tree() already does for the root sb. Fixes: bf109c64040f ("fuse: implement crossmounts") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Greg Kurz <groug@kaod.org> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d92d88f0568e97c437eeb79d9c9609bd8277406f upstream.

If fuse_fill_super_submount() returns an error, the error path
triggers a crash:

[   26.206673] BUG: kernel NULL pointer dereference, address: 0000000000000000
[...]
[   26.226362] RIP: 0010:__list_del_entry_valid+0x25/0x90
[...]
[   26.247938] Call Trace:
[   26.248300]  fuse_mount_remove+0x2c/0x70 [fuse]
[   26.248892]  virtio_kill_sb+0x22/0x160 [virtiofs]
[   26.249487]  deactivate_locked_super+0x36/0xa0
[   26.250077]  fuse_dentry_automount+0x178/0x1a0 [fuse]

The crash happens because fuse_mount_remove() assumes that the FUSE
mount was already added to list under the FUSE connection, but this
only done after fuse_fill_super_submount() has returned success.

This means that until fuse_fill_super_submount() has returned success,
the FUSE mount isn't actually owned by the superblock. We should thus
reclaim ownership by clearing sb->s_fs_info, which will skip the call
to fuse_mount_remove(), and perform rollback, like virtio_fs_get_tree()
already does for the root sb.

Fixes: bf109c64040f ("fuse: implement crossmounts")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-05-02T16:14:01+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-05-02T16:14:01+00:00 27787ba3fa4904422b3928b898d1bd3d74d98bea Pull misc vfs updates from Al Viro: "Assorted stuff all over the place" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: useful constants: struct qstr for ".." hostfs_open(): don't open-code file_dentry() whack-a-mole: kill strlen_user() (again) autofs: should_expire() argument is guaranteed to be positive apparmor:match_mn() - constify devpath argument buffer: a small optimization in grow_buffers get rid of autofs_getpath() constify dentry argument of dentry_path()/dentry_path_raw() 
Pull misc vfs updates from Al Viro:
 "Assorted stuff all over the place"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  useful constants: struct qstr for ".."
  hostfs_open(): don't open-code file_dentry()
  whack-a-mole: kill strlen_user() (again)
  autofs: should_expire() argument is guaranteed to be positive
  apparmor:match_mn() - constify devpath argument
  buffer: a small optimization in grow_buffers
  get rid of autofs_getpath()
  constify dentry argument of dentry_path()/dentry_path_raw()
Merge tag 'fuse-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse 2021-04-30T22:23:16+00:00 Linus Torvalds torvalds@linux-foundation.org 2021-04-30T22:23:16+00:00 9ec1efbf9ded6cf38fd910c6fe943972d970f384 Pull fuse updates from Miklos Szeredi: - Fix a page locking bug in write (introduced in 2.6.26) - Allow sgid bit to be killed in setacl() - Miscellaneous fixes and cleanups * tag 'fuse-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: cuse: simplify refcount cuse: prevent clone virtiofs: fix userns virtiofs: remove useless function virtiofs: split requests that exceed virtqueue size virtiofs: fix memory leak in virtio_fs_probe() fuse: invalidate attrs when page writeback completes fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID fuse: extend FUSE_SETXATTR request fuse: fix matching of FUSE_DEV_IOC_CLONE command fuse: fix a typo fuse: don't zero pages twice fuse: fix typo for fuse_conn.max_pages comment fuse: fix write deadlock 
Pull fuse updates from Miklos Szeredi:

 - Fix a page locking bug in write (introduced in 2.6.26)

 - Allow sgid bit to be killed in setacl()

 - Miscellaneous fixes and cleanups

* tag 'fuse-update-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  cuse: simplify refcount
  cuse: prevent clone
  virtiofs: fix userns
  virtiofs: remove useless function
  virtiofs: split requests that exceed virtqueue size
  virtiofs: fix memory leak in virtio_fs_probe()
  fuse: invalidate attrs when page writeback completes
  fuse: add a flag FUSE_SETXATTR_ACL_KILL_SGID to kill SGID
  fuse: extend FUSE_SETXATTR request
  fuse: fix matching of FUSE_DEV_IOC_CLONE command
  fuse: fix a typo
  fuse: don't zero pages twice
  fuse: fix typo for fuse_conn.max_pages comment
  fuse: fix write deadlock