a3a847a885
I am repasting here what I posted on the source code originally: /* * turns out path_umount backport is completely unneeded * we copy the trick used on strncpy_from_unsafe_user / strncpy_from_user_nofault * https://elixir.bootlin.com/linux/v4.4.302/source/mm/maccess.c#L184 * basically * * mm_segment_t old_fs = get_fs(); // remember original fs segment * set_fs(USER_DS); // or KERNEL_DS * * do_whatever_in_userspace(); * set_fs(old_fs); // restore fs segment * * * kernel -> user, KERNEL_DS, user -> kernel, USER_DS * * so yes, we can try to straight up call a syscall from kernel space * * NOTE: on newer kernels you can use force_uaccess_begin + force_uaccess_end * ref: https://elixir.bootlin.com/linux/v5.10.237/source/mm/maccess.c#L250 * */ path_umount backport now optional — neat trick, werks, what can I say. Backports? Nah, we’re good. Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>