When a user's CE key is removed, write "2" to /proc/sys/vm/drop_caches
rather than "3". This avoids unnecessarily evicting the pagecache of
in-use inodes. It's only necessary to evict the inodes of the relevant
encrypted files, and these are already sync'ed and no longer in-use.
For this mode "2" suffices, as this evicts "reclaimable slab objects",
including inodes; and evicting an inode implies evicting its pagecache.
This matches the recommendation I've made in the documentation for the
fscrypt kernel feature at
https://www.kernel.org/doc/html/latest/filesystems/fscrypt.html#online-attacks
Test: Sanity check that directories are still "locked" properly:
Unlock device with PIN. Then in adb shell: 'stop; start;
sleep 10; ls /data/data/' still shows filenames in ciphertext form.
Change-Id: I1bdf3c420ebf63e98cc314498211061ea36f2942
Use vold version of writeStringToFile which fsync files, and
manually fsync directories after initialize global DE
(cherry picked from commit a98464f688)
Bug: 71810347
Test: Build pass and reboot stress test.
Original boot failure symptom is NOT reproducible.
Change-Id: I1ca8f8cf0ccfd01075a9c33f79042e58d99aea26
Merged-In: I1ca8f8cf0ccfd01075a9c33f79042e58d99aea26
Device can't start up after the following steps:
1. set screen lock to PIN/Pattern/Password
2. set screen lock to Swipe/None
3. power down immediately after pressing "YES, REMOVE"
4. reboot
failed log:
Failed to read from /data/misc/vold/user_keys/ce/0/current/keymaster_key_blob
root cause:
flushing data failed because of power down
issue:
https://partnerissuetracker.corp.google.com/u/1/issues/119382750
We support file-based encryption on both ext4 and f2fs now, and the
kernel API is the same. So rename things appropriately in vold:
e4crypt => fscrypt
ext4enc => fscrypt
Ext4Crypt => FsCrypt
EXT4_* => FS_*
ext4_encryption_key => fscrypt_key
Additionally, the common functions shared by 'vold' and 'init' are now
in libfscrypt rather than ext4_utils. So update vold to link to
libfscrypt and include the renamed headers.
Note: there's a chance of 'fscrypt' being confused with the dm-crypt
based encryption code in vold which is called 'cryptfs'. However,
fscrypt is the name used in the kernel for ext4/f2fs/ubifs encryption,
and it's preferable to use the same name in userspace.
Test: built, booted device with f2fs encryption
Change-Id: I2a46a49f30d9c0b73d6f6fe09e4a4904d4138ff6
