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Fsync directories before delete key

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The boot failure symptom is reproduced on Walleye devices. System boots
up after taking OTA and try to upgrade key, but keymaster returns "failed
to ugprade key". Device reboots to recovery mode because of the failure,
and finally trapped in bootloader screen. Possible scenario is:

(After taking OTA)
vold sends old key and op=UPGRADE to keymaster
keymaster creates and saves new key to RPMB, responses new key to vold
vold saves new key as temp key
vold renames temp key to main key -------------- (1) -- still in cache
vold sends old key and op=DELETE_KEY to keymaster
keymaster removes old key from RPMB ------------ (2) -- write directly to RPMB
==> SYSTEM INTERRUPTED BY CRASH OR SOMETHING; ALL CACHE LOST.
==> System boots up, key in RPMB is deleted but key in storage is old key.

Solution: A Fsync is required between (1) and (2) to cover this case.

Detail analysis: b/124279741#comment21

Bug: 112145641
Bug: 124279741
Test: Insert fault right after deleteKey in vold::begin (KeyStorage.cpp),
      original boot failure symptom is NOT reproducible.
Change-Id: Ia042b23699c37c94758fb660aecec64d39f39738
Merged-In: Ib8c349d6d033f86b247f4b35b8354d97cf249d26
(cherry picked from commit a598e04a91)
This commit is contained in:
Woody Lin 2019-03-11 20:58:20 +08:00 committed by android-build-team Robot
parent 4b9c47d70f
commit 0496e3698f
1 changed files with 4 additions and 0 deletions
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4
KeyStorage.cpp
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@ -223,6 +223,10 @@ static KeymasterOperation begin(Keymaster& keymaster, const std::string& dir,
PLOG(ERROR) << "Unable to move upgraded key to location: " << kmKeyPath; PLOG(ERROR) << "Unable to move upgraded key to location: " << kmKeyPath;
return KeymasterOperation(); return KeymasterOperation();
} }
if (!android::vold::FsyncDirectory(dir)) {
LOG(ERROR) << "Key dir sync failed: " << dir;
return KeymasterOperation();
}
if (!keymaster.deleteKey(kmKey)) { if (!keymaster.deleteKey(kmKey)) {
LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir; LOG(ERROR) << "Key deletion failed during upgrade, continuing anyway: " << dir;
} }