On Mon, Jun 10, 2019 at 07:53:30PM +0100, Catalin Marinas wrote:
On Mon, Jun 10, 2019 at 11:07:03AM -0700, Kees Cook wrote:
On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 3767fb21a5b8..fd191c5b92aa 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -552,3 +552,18 @@ void arch_setup_new_exec(void) ptrauth_thread_init_user(current); }
+/*
- Enable the relaxed ABI allowing tagged user addresses into the kernel.
- */
+int untagged_uaddr_set_mode(unsigned long arg) +{
- if (is_compat_task())
return -ENOTSUPP;- if (arg)
return -EINVAL;- set_thread_flag(TIF_UNTAGGED_UADDR);
- return 0;
+}
I think this should be paired with a flag clearing in copy_thread(), yes? (i.e. each binary needs to opt in)
It indeed needs clearing though not in copy_thread() as that's used on clone/fork but rather in flush_thread(), called on the execve() path.
Ah! Yes, thanks.
And a note to myself: I think PR_UNTAGGED_ADDR (not UADDR) looks better in a uapi header, the user doesn't differentiate between uaddr and kaddr.
Good point. I would agree. :)