linux.git/drivers/vfio/mdev/mdev_sysfs.c, branch v6.18.21

vfio/mdev: Constify struct kobj_type

2024-09-06T14:20:52+00:00

This 'struct kobj_type' is not modified. It is only used in
kobject_init_and_add() which takes a 'const struct kobj_type *ktype'
parameter.

Constifying this structure and moving it to a read-only section,
and this can increase over all security.

```
[Before]
   text   data    bss    dec    hex    filename
   2372    600      0   2972    b9c    drivers/vfio/mdev/mdev_sysfs.o

[After]
   text   data    bss    dec    hex    filename
   2436    568      0   3004    bbc    drivers/vfio/mdev/mdev_sysfs.o
```

Signed-off-by: Hongbo Li 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20240904011837.2010444-1-lihongbo22@huawei.com
Signed-off-by: Alex Williamson

vfio/mdev: Fix a null-ptr-deref bug for mdev_unregister_parent()

2023-09-22T18:48:04+00:00

Inject fault while probing mdpy.ko, if kstrdup() of create_dir() fails in
kobject_add_internal() in kobject_init_and_add() in mdev_type_add()
in parent_create_sysfs_files(), it will return 0 and probe successfully.
And when rmmod mdpy.ko, the mdpy_dev_exit() will call
mdev_unregister_parent(), the mdev_type_remove() may traverse uninitialized
parent->types[i] in parent_remove_sysfs_files(), and it will cause
below null-ptr-deref.

If mdev_type_add() fails, return the error code and kset_unregister()
to fix the issue.

 general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
 KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
 CPU: 2 PID: 10215 Comm: rmmod Tainted: G        W        N 6.6.0-rc2+ #20
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
 RIP: 0010:__kobject_del+0x62/0x1c0
 Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 51 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 28 48 8d 7d 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 24 01 00 00 48 8b 75 10 48 89 df 48 8d 6b 3c e8
 RSP: 0018:ffff88810695fd30 EFLAGS: 00010202
 RAX: dffffc0000000000 RBX: ffffffffa0270268 RCX: 0000000000000000
 RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000010
 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed10233a4ef1
 R10: ffff888119d2778b R11: 0000000063666572 R12: 0000000000000000
 R13: fffffbfff404e2d4 R14: dffffc0000000000 R15: ffffffffa0271660
 FS:  00007fbc81981540(0000) GS:ffff888119d00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fc14a142dc0 CR3: 0000000110a62003 CR4: 0000000000770ee0
 DR0: ffffffff8fb0bce8 DR1: ffffffff8fb0bce9 DR2: ffffffff8fb0bcea
 DR3: ffffffff8fb0bceb DR6: 00000000fffe0ff0 DR7: 0000000000000600
 PKRU: 55555554
 Call Trace:
  
  ? die_addr+0x3d/0xa0
  ? exc_general_protection+0x144/0x220
  ? asm_exc_general_protection+0x22/0x30
  ? __kobject_del+0x62/0x1c0
  kobject_del+0x32/0x50
  parent_remove_sysfs_files+0xd6/0x170 [mdev]
  mdev_unregister_parent+0xfb/0x190 [mdev]
  ? mdev_register_parent+0x270/0x270 [mdev]
  ? find_module_all+0x9d/0xe0
  mdpy_dev_exit+0x17/0x63 [mdpy]
  __do_sys_delete_module.constprop.0+0x2fa/0x4b0
  ? module_flags+0x300/0x300
  ? __fput+0x4e7/0xa00
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x46/0xb0
 RIP: 0033:0x7fbc813221b7
 Code: 73 01 c3 48 8b 0d d1 8c 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a1 8c 2c 00 f7 d8 64 89 01 48
 RSP: 002b:00007ffe780e0648 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
 RAX: ffffffffffffffda RBX: 00007ffe780e06a8 RCX: 00007fbc813221b7
 RDX: 000000000000000a RSI: 0000000000000800 RDI: 000055e214df9b58
 RBP: 000055e214df9af0 R08: 00007ffe780df5c1 R09: 0000000000000000
 R10: 00007fbc8139ecc0 R11: 0000000000000206 R12: 00007ffe780e0870
 R13: 00007ffe780e0ed0 R14: 000055e214df9260 R15: 000055e214df9af0
  
 Modules linked in: mdpy(-) mdev vfio_iommu_type1 vfio [last unloaded: mdpy]
 Dumping ftrace buffer:
    (ftrace buffer empty)
 ---[ end trace 0000000000000000 ]---
 RIP: 0010:__kobject_del+0x62/0x1c0
 Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 51 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 28 48 8d 7d 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 24 01 00 00 48 8b 75 10 48 89 df 48 8d 6b 3c e8
 RSP: 0018:ffff88810695fd30 EFLAGS: 00010202
 RAX: dffffc0000000000 RBX: ffffffffa0270268 RCX: 0000000000000000
 RDX: 0000000000000002 RSI: 0000000000000004 RDI: 0000000000000010
 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed10233a4ef1
 R10: ffff888119d2778b R11: 0000000063666572 R12: 0000000000000000
 R13: fffffbfff404e2d4 R14: dffffc0000000000 R15: ffffffffa0271660
 FS:  00007fbc81981540(0000) GS:ffff888119d00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fc14a142dc0 CR3: 0000000110a62003 CR4: 0000000000770ee0
 DR0: ffffffff8fb0bce8 DR1: ffffffff8fb0bce9 DR2: ffffffff8fb0bcea
 DR3: ffffffff8fb0bceb DR6: 00000000fffe0ff0 DR7: 0000000000000600
 PKRU: 55555554
 Kernel panic - not syncing: Fatal exception
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Kernel Offset: disabled
 Rebooting in 1 seconds..

Fixes: da44c340c4fe ("vfio/mdev: simplify mdev_type handling")
Signed-off-by: Jinjie Ruan 
Reviewed-by: Eric Farman 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20230918115551.1423193-1-ruanjinjie@huawei.com
Signed-off-by: Alex Williamson

vfio/mdev: Use sysfs_emit() to instead of sprintf()

2023-01-30T19:16:13+00:00

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: Bo Liu 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20230129084117.2384-1-liubo03@inspur.com
Signed-off-by: Alex Williamson

vfio/mdev: add mdev available instance checking to the core

2022-10-04T18:06:58+00:00

Many of the mdev drivers use a simple counter for keeping track of the
available instances. Move this code to the core code and store the counter
in the mdev_parent. Implement it using correct locking, fixing mdpy.

Drivers just provide the value in the mdev_driver at registration time
and the core code takes care of maintaining it and exposing the value in
sysfs.

[hch: count instances per-parent instead of per-type, use an atomic_t
 to avoid taking mdev_list_lock in the show method]

Signed-off-by: Jason Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the description sysfs into the core code

2022-10-04T18:06:58+00:00

Every driver just emits a string, simply add a method to the mdev_driver
to return it and provide a standard sysfs show function.

Remove the now unused types_attrs field in struct mdev_driver and the
support code for it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Link: https://lore.kernel.org/r/20220923092652.100656-14-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the available_instance sysfs into the core code

2022-10-04T18:06:58+00:00

Every driver just print a number, simply add a method to the mdev_driver
to return it and provide a standard sysfs show function.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-13-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the name sysfs into the core code

2022-10-04T18:06:58+00:00

Every driver just emits a static string, simply add a field to the
mdev_type for the driver to fill out or fall back to the sysfs name and
provide a standard sysfs show function.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-12-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the device_api sysfs into the core code

2022-10-04T18:06:58+00:00

Every driver just emits a static string, simply feed it through the ops
and provide a standard sysfs show function.

Signed-off-by: Jason Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-11-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: simplify mdev_type handling

2022-10-04T18:06:58+00:00

Instead of abusing struct attribute_group to control initialization of
struct mdev_type, just define the actual attributes in the mdev_driver,
allocate the mdev_type structures in the caller and pass them to
mdev_register_parent.

This allows the caller to use container_of to get at the containing
structure and thus significantly simplify the code.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-6-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: embedd struct mdev_parent in the parent data structure

2022-10-04T18:06:58+00:00

Simplify mdev_{un}register_device by requiring the caller to pass in
a structure allocate as part of the parent device structure.  This
removes the need for a list of parents and the separate mdev_parent
refcount as we can simplify rely on the reference to the parent device.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-5-hch@lst.de
Signed-off-by: Alex Williamson