vold: Add a versioned superblock to secure containers.
Add an un-encrypted superblock to the end of a secure container to
help identify the crypto cipher used. This is required in order to
provide some semblence of versioning, in case we have cause to
change the crypto type on an update - say for example switching
from software to hardware encryption, or from 128 -> a zillion
bit keys.
NOTE: This format is incompatible with previous secure containers.
After this change they will no longer be mountable.
Signed-off-by: San Mehat <san@google.com>
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index ce01275..8f1cb52 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -38,6 +38,7 @@
#include "Fat.h"
#include "Devmapper.h"
#include "Process.h"
+#include "Asec.h"
VolumeManager *VolumeManager::sInstance = NULL;
@@ -168,6 +169,11 @@
int VolumeManager::createAsec(const char *id, unsigned int numSectors,
const char *fstype, const char *key, int ownerUid) {
+ struct asec_superblock sb;
+ memset(&sb, 0, sizeof(sb));
+
+ sb.magic = ASEC_SB_MAGIC;
+ sb.ver = ASEC_SB_VER;
if (numSectors < ((1024*1024)/512)) {
LOGE("Invalid container size specified (%d sectors)", numSectors);
@@ -191,7 +197,18 @@
return -1;
}
- if (Loop::createImageFile(asecFileName, numSectors)) {
+ /*
+ * Add some headroom
+ */
+ unsigned fatSize = (((numSectors * 4) / 512) + 1) * 2;
+ unsigned numImgSectors = numSectors + fatSize + 2;
+
+ if (numImgSectors % 63) {
+ numImgSectors += (63 - (numImgSectors % 63));
+ }
+
+ // Add +1 for our superblock which is at the end
+ if (Loop::createImageFile(asecFileName, numImgSectors + 1)) {
LOGE("ASEC image file creation failed (%s)", strerror(errno));
return -1;
}
@@ -207,7 +224,9 @@
bool cleanupDm = false;
if (strcmp(key, "none")) {
- if (Devmapper::create(id, loopDevice, key, numSectors, dmDevice,
+ // XXX: This is all we support for now
+ sb.c_cipher = ASEC_SB_C_CIPHER_TWOFISH;
+ if (Devmapper::create(id, loopDevice, key, numImgSectors, dmDevice,
sizeof(dmDevice))) {
LOGE("ASEC device mapping failed (%s)", strerror(errno));
Loop::destroyByDevice(loopDevice);
@@ -216,15 +235,54 @@
}
cleanupDm = true;
} else {
+ sb.c_cipher = ASEC_SB_C_CIPHER_NONE;
strcpy(dmDevice, loopDevice);
}
+ /*
+ * Drop down the superblock at the end of the file
+ */
+
+ int sbfd = open(loopDevice, O_RDWR);
+ if (sbfd < 0) {
+ LOGE("Failed to open new DM device for superblock write (%s)", strerror(errno));
+ if (cleanupDm) {
+ Devmapper::destroy(id);
+ }
+ Loop::destroyByDevice(loopDevice);
+ unlink(asecFileName);
+ return -1;
+ }
+
+ if (lseek(sbfd, (numImgSectors * 512), SEEK_SET) < 0) {
+ close(sbfd);
+ LOGE("Failed to lseek for superblock (%s)", strerror(errno));
+ if (cleanupDm) {
+ Devmapper::destroy(id);
+ }
+ Loop::destroyByDevice(loopDevice);
+ unlink(asecFileName);
+ return -1;
+ }
+
+ if (write(sbfd, &sb, sizeof(sb)) != sizeof(sb)) {
+ close(sbfd);
+ LOGE("Failed to write superblock (%s)", strerror(errno));
+ if (cleanupDm) {
+ Devmapper::destroy(id);
+ }
+ Loop::destroyByDevice(loopDevice);
+ unlink(asecFileName);
+ return -1;
+ }
+ close(sbfd);
+
if (strcmp(fstype, "none")) {
if (strcmp(fstype, "fat")) {
LOGW("Unknown fstype '%s' specified for container", fstype);
}
- if (Fat::format(dmDevice)) {
+ if (Fat::format(dmDevice, numImgSectors)) {
LOGE("ASEC FAT format failed (%s)", strerror(errno));
if (cleanupDm) {
Devmapper::destroy(id);
@@ -467,24 +525,53 @@
char dmDevice[255];
bool cleanupDm = false;
+ int fd;
+ unsigned int nr_sec = 0;
+
+ if ((fd = open(loopDevice, O_RDWR)) < 0) {
+ LOGE("Failed to open loopdevice (%s)", strerror(errno));
+ Loop::destroyByDevice(loopDevice);
+ return -1;
+ }
+
+ if (ioctl(fd, BLKGETSIZE, &nr_sec)) {
+ LOGE("Failed to get loop size (%s)", strerror(errno));
+ Loop::destroyByDevice(loopDevice);
+ close(fd);
+ return -1;
+ }
+
+ /*
+ * Validate superblock
+ */
+ struct asec_superblock sb;
+ memset(&sb, 0, sizeof(sb));
+ if (lseek(fd, ((nr_sec-1) * 512), SEEK_SET) < 0) {
+ LOGE("lseek failed (%s)", strerror(errno));
+ close(fd);
+ Loop::destroyByDevice(loopDevice);
+ return -1;
+ }
+ if (read(fd, &sb, sizeof(sb)) != sizeof(sb)) {
+ LOGE("superblock read failed (%s)", strerror(errno));
+ close(fd);
+ Loop::destroyByDevice(loopDevice);
+ return -1;
+ }
+
+ close(fd);
+
+ LOGD("Container sb magic/ver (%.8x/%.2x)", sb.magic, sb.ver);
+ if (sb.magic != ASEC_SB_MAGIC || sb.ver != ASEC_SB_VER) {
+ LOGE("Bad container magic/version (%.8x/%.2x)", sb.magic, sb.ver);
+ Loop::destroyByDevice(loopDevice);
+ errno = EMEDIUMTYPE;
+ return -1;
+ }
+ nr_sec--; // We don't want the devmapping to extend onto our superblock
+
if (strcmp(key, "none")) {
if (Devmapper::lookupActive(id, dmDevice, sizeof(dmDevice))) {
- unsigned int nr_sec = 0;
- int fd;
-
- if ((fd = open(loopDevice, O_RDWR)) < 0) {
- LOGE("Failed to open loopdevice (%s)", strerror(errno));
- Loop::destroyByDevice(loopDevice);
- return -1;
- }
-
- if (ioctl(fd, BLKGETSIZE, &nr_sec)) {
- LOGE("Failed to get loop size (%s)", strerror(errno));
- Loop::destroyByDevice(loopDevice);
- close(fd);
- return -1;
- }
- close(fd);
if (Devmapper::create(id, loopDevice, key, nr_sec,
dmDevice, sizeof(dmDevice))) {
LOGE("ASEC device mapping failed (%s)", strerror(errno));