Re: [PATCH 5.4,4.19] lsm: new security_file_ioctl_compat() hook

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Feb 05, 2024 at 05:29:53PM -0800, Eric Biggers wrote:
> From: Alfred Piccioni <alpic@google.com>
> 
> commit f1bb47a31dff6d4b34fb14e99850860ee74bb003 upstream.
> [Please apply to 5.4-stable and 4.19-stable.  The upstream commit failed
> to apply to these kernels.  This patch resolves the conflicts.]
> 
> Some ioctl commands do not require ioctl permission, but are routed to
> other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is
> done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*).
> 
> However, if a 32-bit process is running on a 64-bit kernel, it emits
> 32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are
> being checked erroneously, which leads to these ioctl operations being
> routed to the ioctl permission, rather than the correct file
> permissions.
> 
> This was also noted in a RED-PEN finding from a while back -
> "/* RED-PEN how should LSM module know it's handling 32bit? */".
> 
> This patch introduces a new hook, security_file_ioctl_compat(), that is
> called from the compat ioctl syscall. All current LSMs have been changed
> to support this hook.
> 
> Reviewing the three places where we are currently using
> security_file_ioctl(), it appears that only SELinux needs a dedicated
> compat change; TOMOYO and SMACK appear to be functional without any
> change.
> 
> Cc: stable@vger.kernel.org
> Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"")
> Signed-off-by: Alfred Piccioni <alpic@google.com>
> Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> [PM: subject tweak, line length fixes, and alignment corrections]
> Signed-off-by: Paul Moore <paul@paul-moore.com>
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Now queued up, thanks.

greg k-h