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  1. 09 Jan, 2016 5 commits
    • Al Viro's avatar
      nbd: use ->compat_ioctl() · 263a3df1
      Al Viro authored 
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      263a3df1
    • Al Viro's avatar
      Merge branch 'for-linus' into work.misc · 6108209c
      Al Viro authored
      6108209c
    • Jann Horn's avatar
      compat_ioctl: don't call do_ioctl under set_fs(KERNEL_DS) · a7f61e89
      Jann Horn authored 
      This replaces all code in fs/compat_ioctl.c that translated
ioctl arguments into a in-kernel structure, then performed
do_ioctl under set_fs(KERNEL_DS), with code that allocates
data on the user stack and can call the VFS ioctl handler
under USER_DS.

This is done as a hardening measure because the caller
does not know what kind of ioctl handler will be invoked,
only that no corresponding compat_ioctl handler exists and
what the ioctl command number is. The accidental
invocation of an unlocked_ioctl handler that unexpectedly
calls copy_to_user could be a severe security issue.
Signed-off-by: default avatarJann Horn <jann@thejh.net>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      a7f61e89
    • Al Viro's avatar
      compat_ioctl: don't pass fd around when not needed · 66cf191f
      Al Viro authored 
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      66cf191f
    • Jann Horn's avatar
      compat_ioctl: don't look up the fd twice · b4341721
      Jann Horn authored 
      In code in fs/compat_ioctl.c that translates ioctl arguments
into a in-kernel structure, then performs sys_ioctl, possibly
under set_fs(KERNEL_DS), this commit changes the sys_ioctl
calls to do_ioctl calls. do_ioctl is a new function that does
the same thing as sys_ioctl, but doesn't look up the fd again.

This change is made to avoid (potential) security issues
because of ioctl handlers that accept one of the ioctl
commands I2C_FUNCS, VIDEO_GET_EVENT, MTIOCPOS, MTIOCGET,
TIOCGSERIAL, TIOCSSERIAL, RTC_IRQP_READ, RTC_EPOCH_READ.
This can happen for multiple reasons:

 - The ioctl command number could be reused.
 - The ioctl handler might not check the full ioctl
   command. This is e.g. true for drm_ioctl.
 - The ioctl handler is very special, e.g. cuse_file_ioctl

The real issue is that set_fs(KERNEL_DS) is used here,
but that's fixed in a separate commit
"compat_ioctl: don't call do_ioctl under set_fs(KERNEL_DS)".

This change mitigates potential security issues by
preventing a race that permits invocation of
unlocked_ioctl handlers under KERNEL_DS through compat
code even if a corresponding compat_ioctl handler exists.

So far, no way has been identified to use this to damage
kernel memory without having CAP_SYS_ADMIN in the init ns
(with the capability, doing reads/writes at arbitrary
kernel addresses should be easy through CUSE's ioctl
handler with FUSE_IOCTL_UNRESTRICTED set).

[AV: two missed sys_ioctl() taken care of]
Signed-off-by: default avatarJann Horn <jann@thejh.net>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      b4341721
  3. 06 Jan, 2016 8 commits
  5. 04 Jan, 2016 22 commits
  7. 03 Jan, 2016 3 commits
  9. 31 Dec, 2015 2 commits
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