[OnePlus 7 & 7 Pro Cross Device Development] vitaly51370:
OnePlus7Pro:/ $ su
OnePlus7Pro:/ # ls -laZ /sdcard/DualBoot/
total 8
drwxrwx--- 2 root everybody u:object_r:fuse:s0 4096 2021-03-06 14:57 SDcard_b
drwxr-xr-x 24 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 System_b
OnePlus7Pro:/ # ls -laZ /sdcard/DualBoot/System_b
ls: /sdcard/DualBoot/System_b: Permission denied
1|OnePlus7Pro:/ #

OnePlus7Pro:/ # setenforce 0
OnePlus7Pro:/ # getenforce
Permissive
OnePlus7Pro:/ # ls -laZ /sdcard/DualBoot/System_b
ls: /sdcard/DualBoot/System_b/product: Function not implemented
ls: /sdcard/DualBoot/System_b/d: Function not implemented
ls: /sdcard/DualBoot/System_b/bin: Function not implemented
ls: /sdcard/DualBoot/System_b/sdcard: Function not implemented
ls: /sdcard/DualBoot/System_b/charger: Function not implemented
ls: /sdcard/DualBoot/System_b/init: Function not implemented
ls: /sdcard/DualBoot/System_b/cache: Function not implemented
ls: /sdcard/DualBoot/System_b/etc: Function not implemented
ls: /sdcard/DualBoot/System_b/product_services: Function not implemented
ls: /sdcard/DualBoot/System_b/bugreports: Function not implemented
ls: /sdcard/DualBoot/System_b/default.prop: Function not implemented
ls: /sdcard/DualBoot/System_b/charger_log: Function not implemented
total 188
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 acct
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 apex
dr-xr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 config
drwxrwx--x 2 system system u:object_r:fuse:s0 4096 2009-01-01 02:00 data
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 debug_ramdisk
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 dev
-rwxr-x--- 1 root shell u:object_r:fuse:s0 2383 2009-01-01 02:00 init.environ.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 136 2009-01-01 02:00 init.oem_ftm.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 37596 2009-01-01 02:00 init.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 3171 2009-01-01 02:00 init.recovery.qcom.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 12922 2009-01-01 02:00 init.usb.configfs.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 6906 2009-01-01 02:00 init.usb.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 563 2009-01-01 02:00 init.zygote32.rc
-rwxr-x--- 1 root shell u:object_r:fuse:s0 981 2009-01-01 02:00 init.zygote64_32.rc
drwx------ 2 root root u:object_r:fuse:s0 16384 2009-01-01 02:00 lost+found
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 metadata
drwxr-xr-x 2 root system u:object_r:fuse:s0 4096 2009-01-01 02:00 mnt
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 odm
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 oem
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 oneplus
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 op1
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 op2
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 postinstall
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 proc
drwxr-xr-x 3 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 res
drwxr-x--- 2 root shell u:object_r:fuse:s0 4096 2009-01-01 02:00 sbin
drwxr-x--x 2 root sdcard_r u:object_r:fuse:s0 4096 2009-01-01 02:00 storage
drwxr-xr-x 2 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 sys
drwxr-xr-x 18 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 system
-rw-r--r-- 1 root root u:object_r:fuse:s0 2608 2009-01-01 02:00 ueventd.rc
drwxr-xr-x 2 root shell u:object_r:fuse:s0 4096 2009-01-01 02:00 vendor
1|OnePlus7Pro:/ # ls -laZ /sdcard/DualBoot/
total 8
drwxrwx--- 2 root everybody u:object_r:fuse:s0 4096 2021-03-06 14:57 SDcard_b
drwxr-xr-x 24 root root u:object_r:fuse:s0 4096 2009-01-01 02:00 System_b
OnePlus7Pro:/ #

When switching Permissive everything works.