Tool to fix the fs_size in the crypto footer

The GPT of HSPA Prime devices is incorrect when it comes from the factory.
Flashing a new bootloader fixes the GPT, but if the user had already
encrypted the device, the old size of the partition is recorded in the
crypto footer.  If the size if not updated, the device will not be able
to boot after the OTA, so add a new command to fix the fs_size field in
the crypto footer for Prime devices.

Change-Id: Ied4b592973d3d5c36c478b7fb32d59ac9e9611b0

2 files changed, 66 insertions, 1 deletions

diff --git a/recovery/Android.mk b/recovery/Android.mk
index 585db84..0034dc8 100644
--- a/recovery/Android.mk
+++ b/recovery/Android.mk
@@ -17,7 +17,7 @@ include $(CLEAR_VARS)
 # Edify extension functions for doing bootloader updates on Tuna devices.
 
 LOCAL_MODULE_TAGS := optional
-LOCAL_C_INCLUDES += bootable/recovery
+LOCAL_C_INCLUDES += bootable/recovery system/vold
 LOCAL_SRC_FILES := recovery_updater.c bootloader.c
 
 # should match TARGET_RECOVERY_UPDATER_LIBS set in BoardConfig.mk
diff --git a/recovery/recovery_updater.c b/recovery/recovery_updater.c
index 02963f5..0c49f9a 100644
--- a/recovery/recovery_updater.c
+++ b/recovery/recovery_updater.c
@@ -19,6 +19,11 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <cryptfs.h>
 
 #include "edify/expr.h"
 #include "bootloader.h"
@@ -55,8 +60,68 @@ Value* WriteBootloaderFn(const char* name, State* state, int argc, Expr* argv[])
     return StringValue(strdup(result == 0 ? "t" : ""));
 }
 
+/*
+ * The size of the userdata partition for HSPA Galaxy Nexus devices is incorrect
+ * in the partition as it comes from the factory.  Updating the bootloader fixes
+ * the partition table, and makes the size of the userdata partition 1 sector
+ * smaller.  However, if the user had encrypted their device with the original
+ * incorrect size of the partition table, the crypto footer has saved that
+ * size, and tries to map that much data when decrypting.  However, with the
+ * new partition table, that size is too big to be mapped, and the kernel
+ * throws an error, and the user can't decrypt and boot the device after the
+ * OTA is installed.  Oops!
+ *
+ * The fix here is to recognize a crypto footer that has the wrong size, and
+ * update it to the new correct size.  This program should be run as part of
+ * the recovery script for HSPA Galaxy Nexus devices.
+ */
+
+#define BAD_SIZE  0x01b14fdfULL
+#define GOOD_SIZE 0x01b14fdeULL
+
+#define HSPA_PRIME_KEY_PARTITION "/dev/block/platform/omap/omap_hsmmc.0/by-name/metadata"
+
+Value* FsSizeFixFn(const char* name, State* state, int argc, Expr* argv[])
+{
+    struct crypt_mnt_ftr ftr;
+    int fd;
+
+    if (argc != 0) {
+        return ErrorAbort(state, "%s() expects 0 args, got %d", name, argc);
+    }
+
+    if ((fd = open(HSPA_PRIME_KEY_PARTITION, O_RDWR)) == -1) {
+        return ErrorAbort(state, "%s() Cannot open %s\n", name, HSPA_PRIME_KEY_PARTITION);
+    }
+
+    if (read(fd, &ftr, sizeof(ftr)) != sizeof(ftr)) {
+        close(fd);
+        return ErrorAbort(state, "%s() Cannot read crypto footer %s\n", name, HSPA_PRIME_KEY_PARTITION);
+    }
+
+   if ((ftr.magic == CRYPT_MNT_MAGIC) && (ftr.fs_size == BAD_SIZE)) {
+        ftr.fs_size = GOOD_SIZE;
+        if (lseek(fd, 0, SEEK_SET) == 0) {
+            if (write(fd, &ftr, sizeof(ftr)) == sizeof(ftr)) {
+                fsync(fd); /* Make sure it gets to the disk */
+                fprintf(stderr, "Footer updated\n");
+                close(fd);
+                return StringValue(strdup("t"));
+            }
+        }
+        close(fd);
+        return ErrorAbort(state, "%s() Cannot seek or write crypto footer %s\n", name, HSPA_PRIME_KEY_PARTITION);
+    }
+
+    /* Nothing to do */
+    fprintf(stderr, "Footer doesn't need updating\n");
+    close(fd);
+    return StringValue(strdup("t"));
+}
+
 void Register_librecovery_updater_tuna() {
     fprintf(stderr, "installing samsung updater extensions\n");
 
     RegisterFunction("samsung.write_bootloader", WriteBootloaderFn);
+    RegisterFunction("samsung.fs_size_fix", FsSizeFixFn);
 }