Re: [PATCH v3 2/5] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount property

[James Morris]

On Tue, 28 Apr 2020, Mickaël Salaün wrote:

> An LSM doesn't get path information related to an access request to open
> an inode.  This new (internal) MAY_EXECMOUNT flag enables an LSM to
> check if the underlying mount point of an inode is marked as executable.
> This is useful to implement a security policy taking advantage of the
> noexec mount option.
> 
> This flag is set according to path_noexec(), which checks if a mount
> point is mounted with MNT_NOEXEC or if the underlying superblock is
> SB_I_NOEXEC.
> 
> Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx>
> Reviewed-by: Philippe Trébuchet <philippe.trebuchet@xxxxxxxxxxx>
> Reviewed-by: Thibaut Sautereau <thibaut.sautereau@xxxxxxxxxxx>
> Cc: Aleksa Sarai <cyphar@xxxxxxxxxx>
> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>

Are there any existing LSMs which plan to use this aspect?

-- 
James Morris
<jmorris@xxxxxxxxx>