It seems the partition corresponding to /sdcard is formatted as a FAT variant in android. As a result, it does not support ownership/permissions:
/sdcard/Signal $ ls -lrth
total 116M
-rw-rw---- 1 root everybody 116M Oct 2 20:23 signal-2021-10-02-20-23-20.backup
/sdcard/Signal $ whoami
u0_a248
/sdcard/Signal $ chown u0_a248 .
/sdcard/Signal $ ls -lrth
total 116M
-rw-rw---- 1 root everybody 116M Oct 2 20:23 signal-2021-10-02-20-23-20.backup
I would like to ensure that some directory, e.g. /sdcard/Signal is only readable by a few apps, e.g. just Signal and Termux by putting the user ids of the two apps in a group and assigning the directory to that group. In a rooted lineageos, is it possible to have /sdcard be a ext4-formatted partition with support for ownership and permissions?
