On Thu, Sep 7, 2023 at 11:37 AM Mickaël Salaün <mic@xxxxxxxxxxx> wrote:
> On Wed, Sep 06, 2023 at 04:48:04PM -0700, Casey Schaufler wrote:
> > On 9/6/2023 4:22 PM, Paul Moore wrote:
> > > On Aug 28, 2023 Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote:
> > >> Create a system call lsm_get_self_attr() to provide the security
> > >> module maintained attributes of the current process.
> > >> Create a system call lsm_set_self_attr() to set a security
> > >> module maintained attribute of the current process.
> > >> Historically these attributes have been exposed to user space via
> > >> entries in procfs under /proc/self/attr.
> > >>
> > >> The attribute value is provided in a lsm_ctx structure. The structure
> > >> identifies the size of the attribute, and the attribute value. The format
> > >> of the attribute value is defined by the security module. A flags field
> > >> is included for LSM specific information. It is currently unused and must
> > >> be 0. The total size of the data, including the lsm_ctx structure and any
> > >> padding, is maintained as well.
> > >>
> > >> struct lsm_ctx {
> > >> __u64 id;
> > >> __u64 flags;
> > >> __u64 len;
> > >> __u64 ctx_len;
> > >> __u8 ctx[];
> > >> };
> > >>
> > >> Two new LSM hooks are used to interface with the LSMs.
> > >> security_getselfattr() collects the lsm_ctx values from the
> > >> LSMs that support the hook, accounting for space requirements.
> > >> security_setselfattr() identifies which LSM the attribute is
> > >> intended for and passes it along.
> > >>
> > >> Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
> > >> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > >> Reviewed-by: Serge Hallyn <serge@xxxxxxxxxx>
> > >> Reviewed-by: John Johansen <john.johansen@xxxxxxxxxxxxx>
> > >> ---
>
> > >> +int security_getselfattr(unsigned int attr, struct lsm_ctx __user *uctx,
> > >> + size_t __user *size, u32 flags)
> > >> +{
> > >> + struct security_hook_list *hp;
> > >> + struct lsm_ctx lctx = { .id = LSM_ID_UNDEF, };
> > >> + u8 __user *base = (u8 __user *)uctx;
> > >> + size_t total = 0;
> > >> + size_t entrysize;
> > >> + size_t left;
> > >> + bool toobig = false;
> > >> + bool single = false;
> > >> + int count = 0;
> > >> + int rc;
> > >> +
> > >> + if (attr == LSM_ATTR_UNDEF)
> > >> + return -EINVAL;
> > >> + if (size == NULL)
> > >> + return -EINVAL;
> > >> + if (get_user(left, size))
> > >> + return -EFAULT;
> > >> +
> > >> + if (flags) {
> > >> + /*
> > >> + * Only flag supported is LSM_FLAG_SINGLE
> > >> + */
> > >> + if (flags & LSM_FLAG_SINGLE)
> > >> + return -EINVAL;
> > > Should this be something like the following?
> > >
> > > if (flags & ~LSM_FLAG_SINGLE)
> > > return -EINVAL;
> >
> > Yes. I have a fix ready. There are a couple other touch-ups, too.
>
> This is already part of patch 11. It should be squashed here.
So it is, yes, patch 11 should only be selftest code.
--
paul-moore.com
