From fcf24fe62f98c5d44431aa575555569c2c7a29b0 Mon Sep 17 00:00:00 2001 From: San Mehat Date: Wed, 3 Mar 2010 12:37:32 -0800 Subject: [PATCH] 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 --- Asec.h | 42 ++++++++++++++++ Devmapper.cpp | 2 + Fat.cpp | 37 +++++++------- Fat.h | 2 +- Volume.cpp | 2 +- VolumeManager.cpp | 125 +++++++++++++++++++++++++++++++++++++++------- 6 files changed, 170 insertions(+), 40 deletions(-) create mode 100644 Asec.h diff --git a/Asec.h b/Asec.h new file mode 100644 index 0000000..136ad3b --- /dev/null +++ b/Asec.h @@ -0,0 +1,42 @@ +/* + * Copyright (C) 2008 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef _ASEC_H +#define _ASEC_H + +struct asec_superblock { +#define ASEC_SB_MAGIC 0xc0def00d + unsigned int magic; + +#define ASEC_SB_VER 1 + unsigned char ver; + +#define ASEC_SB_C_CIPHER_NONE 0 +#define ASEC_SB_C_CIPHER_TWOFISH 1 +#define ASEC_SB_C_CIPHER_AES 2 + unsigned char c_cipher; + +#define ASEC_SB_C_CHAIN_NONE 0 + unsigned char c_chain; + +#define ASEC_SB_C_OPTS_NONE 0 + unsigned char c_opts; + +#define ASEC_SB_C_MODE_NONE 0 + unsigned char c_mode; +} __attribute__((packed)); + +#endif diff --git a/Devmapper.cpp b/Devmapper.cpp index 02f7d98..c1aa713 100644 --- a/Devmapper.cpp +++ b/Devmapper.cpp @@ -136,8 +136,10 @@ int Devmapper::create(const char *name, const char *loopFile, const char *key, ioctlInit(io, 4096, name, DM_STATUS_TABLE_FLAG); io->target_count = 1; tgt->status = 0; + tgt->sector_start = 0; tgt->length = numSectors; + strcpy(tgt->target_type, "crypt"); char *cryptParams = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec); diff --git a/Fat.cpp b/Fat.cpp index f85bd8e..94b1039 100644 --- a/Fat.cpp +++ b/Fat.cpp @@ -148,24 +148,11 @@ int Fat::doMount(const char *fsPath, const char *mountPoint, return rc; } -int Fat::format(const char *fsPath) { - unsigned int nr_sec; +int Fat::format(const char *fsPath, unsigned int numSectors) { int fd; - - if ((fd = open(fsPath, O_RDWR)) < 0) { - LOGE("Error opening disk file (%s)", strerror(errno)); - return -1; - } - - if (ioctl(fd, BLKGETSIZE, &nr_sec)) { - LOGE("Unable to get device size (%s)", strerror(errno)); - close(fd); - return -1; - } - close(fd); - - const char *args[9]; + const char *args[11]; int rc; + args[0] = MKDOSFS_PATH; args[1] = "-F"; args[2] = "32"; @@ -173,9 +160,21 @@ int Fat::format(const char *fsPath) { args[4] = "android"; args[5] = "-c"; args[6] = "8"; - args[7] = fsPath; - args[8] = NULL; - rc = logwrap(9, args, 1); + + if (numSectors) { + char tmp[32]; + snprintf(tmp, sizeof(tmp), "%u", numSectors); + const char *size = tmp; + args[7] = "-s"; + args[8] = size; + args[9] = fsPath; + args[10] = NULL; + rc = logwrap(11, args, 1); + } else { + args[7] = fsPath; + args[8] = NULL; + rc = logwrap(9, args, 1); + } if (rc == 0) { LOGI("Filesystem formatted OK"); diff --git a/Fat.h b/Fat.h index ab16a7f..f056090 100644 --- a/Fat.h +++ b/Fat.h @@ -25,7 +25,7 @@ public: static int doMount(const char *fsPath, const char *mountPoint, bool ro, bool remount, int ownerUid, int ownerGid, int permMask, bool createLost); - static int format(const char *fsPath); + static int format(const char *fsPath, unsigned int numSectors); }; #endif diff --git a/Volume.cpp b/Volume.cpp index 83c1c0e..07b96a2 100644 --- a/Volume.cpp +++ b/Volume.cpp @@ -194,7 +194,7 @@ int Volume::formatVol() { sprintf(devicePath, "/dev/block/vold/%d:%d", MAJOR(partNode), MINOR(partNode)); - if (Fat::format(devicePath)) { + if (Fat::format(devicePath, 0)) { LOGE("Failed to format (%s)", strerror(errno)); goto err; } 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::getAsecMountPath(const char *id, char *buffer, int maxlen) { 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 @@ int VolumeManager::createAsec(const char *id, unsigned int numSectors, 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 @@ int VolumeManager::createAsec(const char *id, unsigned int numSectors, 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 @@ int VolumeManager::createAsec(const char *id, unsigned int numSectors, } 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 @@ int VolumeManager::mountAsec(const char *id, const char *key, int ownerUid) { 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));