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UpdaterThread: Work around lying Build.VERSION.SECURITY_PATCH #52

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merged 1 commit into from
Apr 6, 2024
Merged

UpdaterThread: Work around lying Build.VERSION.SECURITY_PATCH #52

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33 changes: 31 additions & 2 deletions app/src/main/java/com/chiller3/custota/updater/UpdaterThread.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -412,14 +412,16 @@ class UpdaterThread(
val postSecurityPatchLevel = metadata.postcondition.securityPatchLevel
val postTimestamp = metadata.postcondition.timestamp * 1000

val securityPatch = getSecurityPatch()

if (metadata.type != OtaMetadata.OtaType.AB) {
throw ValidationException("Not an A/B OTA package")
} else if (!preDevices.contains(Build.DEVICE)) {
throw ValidationException("Mismatched device ID: " +
"current=${Build.DEVICE}, ota=$preDevices")
} else if (postSecurityPatchLevel < Build.VERSION.SECURITY_PATCH) {
} else if (postSecurityPatchLevel < securityPatch) {
throw ValidationException("Downgrading to older security patch is not allowed: " +
"current=${Build.VERSION.SECURITY_PATCH}, ota=$postSecurityPatchLevel")
"current=$securityPatch, ota=$postSecurityPatchLevel")
} else if (postTimestamp < Build.TIME) {
throw ValidationException("Downgrading to older timestamp is not allowed: " +
"current=${Build.TIME}, ota=$postTimestamp")
Expand Down Expand Up @@ -840,5 +842,32 @@ class UpdaterThread(
private val USER_AGENT_UPDATE_ENGINE = "$USER_AGENT update_engine/${Build.VERSION.SDK_INT}"

private const val TIMEOUT_MS = 30_000

private const val PROP_SECURITY_PATCH = "ro.build.version.security_patch"

/**
* Get the OS security patch level.
*
* CalyxOS lies about the value when queried from [Build.VERSION.SECURITY_PATCH]. This will
* return the property value of [PROP_SECURITY_PATCH] and log a warning if the OS lies.
*/
@SuppressLint("PrivateApi")
private fun getSecurityPatch(): String {
val reportedPatch = Build.VERSION.SECURITY_PATCH
val actualPatch = try {
val systemProperties = Class.forName("android.os.SystemProperties")
val get = systemProperties.getDeclaredMethod("get", String::class.java)
get.invoke(null, PROP_SECURITY_PATCH) as String
} catch (e: Exception) {
Log.w(TAG, "Failed to query $PROP_SECURITY_PATCH property", e)
null
}

if (reportedPatch != actualPatch) {
Log.w(TAG, "OS lies about security patch: reported=$reportedPatch, actual=$actualPatch")
}

return actualPatch ?: reportedPatch
}
}
}
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