From 99e3a927e89bd0fa67a13511071260fa02d13fa1 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Fri, 22 May 2015 15:43:50 +0100 Subject: [PATCH] Error correction: Use libfec in fs_mgr Use libfec to read and parse verity metadata to protect against data corruption. Bug: 21893453 Change-Id: I3a3543e0d999316707302b3be8735a7133d22946 --- fs_mgr/Android.mk | 58 +++--- fs_mgr/fs_mgr_verity.cpp | 429 ++++++++++++++++----------------------- init/Android.mk | 3 + 3 files changed, 212 insertions(+), 278 deletions(-) diff --git a/fs_mgr/Android.mk b/fs_mgr/Android.mk index b47199f2b..28fff3f1d 100644 --- a/fs_mgr/Android.mk +++ b/fs_mgr/Android.mk @@ -1,49 +1,59 @@ # Copyright 2011 The Android Open Source Project LOCAL_PATH:= $(call my-dir) + +common_static_libraries := \ + liblogwrap \ + libfec \ + libfec_rs \ + libbase \ + libmincrypt \ + libcrypto_static \ + libext4_utils_static \ + libsquashfs_utils + include $(CLEAR_VARS) - -LOCAL_SRC_FILES:= fs_mgr.c fs_mgr_verity.cpp fs_mgr_fstab.c -LOCAL_SRC_FILES += fs_mgr_format.c fs_mgr_slotselect.c - -LOCAL_C_INCLUDES := $(LOCAL_PATH)/include \ +LOCAL_CLANG := true +LOCAL_SANITIZE := integer +LOCAL_SRC_FILES:= \ + fs_mgr.c \ + fs_mgr_format.c \ + fs_mgr_fstab.c \ + fs_mgr_slotselect.c \ + fs_mgr_verity.cpp +LOCAL_C_INCLUDES := \ + $(LOCAL_PATH)/include \ system/vold \ system/extras/ext4_utils \ - external/openssl/include - + external/openssl/include \ + bootable/recovery LOCAL_MODULE:= libfs_mgr -LOCAL_STATIC_LIBRARIES := liblogwrap libmincrypt libext4_utils_static libsquashfs_utils libbase -LOCAL_C_INCLUDES += system/extras/ext4_utils system/extras/squashfs_utils \ - bootable/recovery +LOCAL_STATIC_LIBRARIES := $(common_static_libraries) LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include LOCAL_CFLAGS := -Werror - ifneq (,$(filter userdebug,$(TARGET_BUILD_VARIANT))) LOCAL_CFLAGS += -DALLOW_ADBD_DISABLE_VERITY=1 endif - include $(BUILD_STATIC_LIBRARY) - - include $(CLEAR_VARS) - +LOCAL_CLANG := true +LOCAL_SANITIZE := integer LOCAL_SRC_FILES:= fs_mgr_main.c - LOCAL_C_INCLUDES := $(LOCAL_PATH)/include - LOCAL_MODULE:= fs_mgr - LOCAL_MODULE_TAGS := optional LOCAL_FORCE_STATIC_EXECUTABLE := true LOCAL_MODULE_PATH := $(TARGET_ROOT_OUT)/sbin LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_UNSTRIPPED) - -LOCAL_STATIC_LIBRARIES := libfs_mgr liblogwrap libcutils liblog libc libmincrypt libext4_utils_static libsquashfs_utils libbase -LOCAL_STATIC_LIBRARIES += libsparse_static libz libselinux +LOCAL_STATIC_LIBRARIES := libfs_mgr \ + $(common_static_libraries) \ + libcutils \ + liblog \ + libc \ + libsparse_static \ + libz \ + libselinux LOCAL_CXX_STL := libc++_static - LOCAL_CFLAGS := -Werror - include $(BUILD_EXECUTABLE) - diff --git a/fs_mgr/fs_mgr_verity.cpp b/fs_mgr/fs_mgr_verity.cpp index 8f7c6a267..c35898243 100644 --- a/fs_mgr/fs_mgr_verity.cpp +++ b/fs_mgr/fs_mgr_verity.cpp @@ -38,8 +38,7 @@ #include "mincrypt/sha.h" #include "mincrypt/sha256.h" -#include "ext4_sb.h" -#include "squashfs_utils.h" +#include "fec/io.h" #include "fs_mgr.h" #include "fs_mgr_priv.h" @@ -47,11 +46,19 @@ #define FSTAB_PREFIX "/fstab." -#define VERITY_METADATA_SIZE 32768 #define VERITY_TABLE_RSA_KEY "/verity_key" #define VERITY_TABLE_HASH_IDX 8 #define VERITY_TABLE_SALT_IDX 9 +#define VERITY_TABLE_OPT_RESTART "restart_on_corruption" +#define VERITY_TABLE_OPT_LOGGING "ignore_corruption" +#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks" + +#define VERITY_TABLE_OPT_FEC_FORMAT \ + "use_fec_from_device %s fec_start %" PRIu64 " fec_blocks %" PRIu64 \ + " fec_roots %u " VERITY_TABLE_OPT_IGNZERO +#define VERITY_TABLE_OPT_FEC_ARGS 9 + #define METADATA_MAGIC 0x01564c54 #define METADATA_TAG_MAX_LENGTH 63 #define METADATA_EOD "eod" @@ -92,7 +99,7 @@ static RSAPublicKey *load_key(const char *path) } if (!fread(key, sizeof(*key), 1, f)) { - ERROR("Could not read key!"); + ERROR("Could not read key!\n"); fclose(f); free(key); return NULL; @@ -109,7 +116,8 @@ static RSAPublicKey *load_key(const char *path) return key; } -static int verify_table(char *signature, char *table, int table_length) +static int verify_table(const uint8_t *signature, const char *table, + uint32_t table_length) { RSAPublicKey *key; uint8_t hash_buf[SHA256_DIGEST_SIZE]; @@ -121,17 +129,17 @@ static int verify_table(char *signature, char *table, int table_length) // Now get the public key from the keyfile key = load_key(VERITY_TABLE_RSA_KEY); if (!key) { - ERROR("Couldn't load verity keys"); + ERROR("Couldn't load verity keys\n"); goto out; } // verify the result if (!RSA_verify(key, - (uint8_t*) signature, + signature, RSANUMBYTES, (uint8_t*) hash_buf, SHA256_DIGEST_SIZE)) { - ERROR("Couldn't verify table."); + ERROR("Couldn't verify table\n"); goto out; } @@ -142,11 +150,11 @@ out: return retval; } -static int invalidate_table(char *table, int table_length) +static int invalidate_table(char *table, size_t table_length) { - int n = 0; - int idx = 0; - int cleared = 0; + size_t n = 0; + size_t idx = 0; + size_t cleared = 0; while (n < table_length) { if (table[n++] == ' ') { @@ -169,177 +177,6 @@ static int invalidate_table(char *table, int table_length) return -1; } -static int squashfs_get_target_device_size(char *blk_device, uint64_t *device_size) -{ - struct squashfs_info sq_info; - - if (squashfs_parse_sb(blk_device, &sq_info) >= 0) { - *device_size = sq_info.bytes_used_4K_padded; - return 0; - } else { - return -1; - } -} - -static int ext4_get_target_device_size(char *blk_device, uint64_t *device_size) -{ - int data_device; - struct ext4_super_block sb; - struct fs_info info; - - info.len = 0; /* Only len is set to 0 to ask the device for real size. */ - - data_device = TEMP_FAILURE_RETRY(open(blk_device, O_RDONLY | O_CLOEXEC)); - if (data_device == -1) { - ERROR("Error opening block device (%s)", strerror(errno)); - return -1; - } - - if (TEMP_FAILURE_RETRY(lseek64(data_device, 1024, SEEK_SET)) < 0) { - ERROR("Error seeking to superblock"); - close(data_device); - return -1; - } - - if (!android::base::ReadFully(data_device, &sb, sizeof(sb))) { - ERROR("Error reading superblock"); - close(data_device); - return -1; - } - - ext4_parse_sb(&sb, &info); - *device_size = info.len; - - close(data_device); - return 0; -} - -static int get_fs_size(char *fs_type, char *blk_device, uint64_t *device_size) { - if (!strcmp(fs_type, "ext4")) { - if (ext4_get_target_device_size(blk_device, device_size) < 0) { - ERROR("Failed to get ext4 fs size on %s.", blk_device); - return -1; - } - } else if (!strcmp(fs_type, "squashfs")) { - if (squashfs_get_target_device_size(blk_device, device_size) < 0) { - ERROR("Failed to get squashfs fs size on %s.", blk_device); - return -1; - } - } else { - ERROR("%s: Unsupported filesystem for verity.", fs_type); - return -1; - } - return 0; -} - -static int read_verity_metadata(uint64_t device_size, char *block_device, char **signature, - char **table) -{ - unsigned magic_number; - unsigned table_length; - int protocol_version; - int device; - int retval = FS_MGR_SETUP_VERITY_FAIL; - - *signature = NULL; - - if (table) { - *table = NULL; - } - - device = TEMP_FAILURE_RETRY(open(block_device, O_RDONLY | O_CLOEXEC)); - if (device == -1) { - ERROR("Could not open block device %s (%s).\n", block_device, strerror(errno)); - goto out; - } - - if (TEMP_FAILURE_RETRY(lseek64(device, device_size, SEEK_SET)) < 0) { - ERROR("Could not seek to start of verity metadata block.\n"); - goto out; - } - // check the magic number - if (!android::base::ReadFully(device, &magic_number, sizeof(magic_number))) { - ERROR("Couldn't read magic number!\n"); - goto out; - } - -#ifdef ALLOW_ADBD_DISABLE_VERITY - if (magic_number == VERITY_METADATA_MAGIC_DISABLE) { - retval = FS_MGR_SETUP_VERITY_DISABLED; - INFO("Attempt to cleanly disable verity - only works in USERDEBUG"); - goto out; - } -#endif - - if (magic_number != VERITY_METADATA_MAGIC_NUMBER) { - ERROR("Couldn't find verity metadata at offset %" PRIu64 "!\n", device_size); - goto out; - } - - // check the protocol version - if (!android::base::ReadFully(device, &protocol_version, - sizeof(protocol_version))) { - ERROR("Couldn't read verity metadata protocol version!\n"); - goto out; - } - if (protocol_version != 0) { - ERROR("Got unknown verity metadata protocol version %d!\n", protocol_version); - goto out; - } - - // get the signature - *signature = (char*) malloc(RSANUMBYTES); - if (!*signature) { - ERROR("Couldn't allocate memory for signature!\n"); - goto out; - } - if (!android::base::ReadFully(device, *signature, RSANUMBYTES)) { - ERROR("Couldn't read signature from verity metadata!\n"); - goto out; - } - - if (!table) { - retval = FS_MGR_SETUP_VERITY_SUCCESS; - goto out; - } - - // get the size of the table - if (!android::base::ReadFully(device, &table_length, sizeof(table_length))) { - ERROR("Couldn't get the size of the verity table from metadata!\n"); - goto out; - } - - // get the table + null terminator - *table = static_cast(malloc(table_length + 1)); - if (!*table) { - ERROR("Couldn't allocate memory for verity table!\n"); - goto out; - } - if (!android::base::ReadFully(device, *table, table_length)) { - ERROR("Couldn't read the verity table from metadata!\n"); - goto out; - } - - (*table)[table_length] = 0; - retval = FS_MGR_SETUP_VERITY_SUCCESS; - -out: - if (device != -1) - close(device); - - if (retval != FS_MGR_SETUP_VERITY_SUCCESS) { - free(*signature); - *signature = NULL; - - if (table) { - free(*table); - *table = NULL; - } - } - - return retval; -} - static void verity_ioctl_init(struct dm_ioctl *io, char *name, unsigned flags) { memset(io, 0, DM_BUF_SIZE); @@ -379,8 +216,76 @@ static int get_verity_device_name(struct dm_ioctl *io, char *name, int fd, char return 0; } -static int load_verity_table(struct dm_ioctl *io, char *name, uint64_t device_size, int fd, char *table, - int mode) +struct verity_table_params { + const char *table; + int mode; + struct fec_ecc_metadata ecc; + const char *ecc_dev; +}; + +typedef bool (*format_verity_table_func)(char *buf, const size_t bufsize, + const struct verity_table_params *params); + +static bool format_verity_table(char *buf, const size_t bufsize, + const struct verity_table_params *params) +{ + const char *mode_flag = NULL; + int res = -1; + + if (params->mode == VERITY_MODE_RESTART) { + mode_flag = VERITY_TABLE_OPT_RESTART; + } else if (params->mode == VERITY_MODE_LOGGING) { + mode_flag = VERITY_TABLE_OPT_LOGGING; + } + + if (params->ecc.valid) { + if (mode_flag) { + res = snprintf(buf, bufsize, + "%s %u %s " VERITY_TABLE_OPT_FEC_FORMAT, + params->table, 1 + VERITY_TABLE_OPT_FEC_ARGS, mode_flag, params->ecc_dev, + params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots); + } else { + res = snprintf(buf, bufsize, + "%s %u " VERITY_TABLE_OPT_FEC_FORMAT, + params->table, VERITY_TABLE_OPT_FEC_ARGS, params->ecc_dev, + params->ecc.start / FEC_BLOCKSIZE, params->ecc.blocks, params->ecc.roots); + } + } else if (mode_flag) { + res = snprintf(buf, bufsize, "%s 2 " VERITY_TABLE_OPT_IGNZERO " %s", params->table, + mode_flag); + } else { + res = strlcpy(buf, params->table, bufsize); + } + + if (res < 0 || (size_t)res >= bufsize) { + ERROR("Error building verity table; insufficient buffer size?\n"); + return false; + } + + return true; +} + +static bool format_legacy_verity_table(char *buf, const size_t bufsize, + const struct verity_table_params *params) +{ + int res; + + if (params->mode == VERITY_MODE_EIO) { + res = strlcpy(buf, params->table, bufsize); + } else { + res = snprintf(buf, bufsize, "%s %d", params->table, params->mode); + } + + if (res < 0 || (size_t)res >= bufsize) { + ERROR("Error building verity table; insufficient buffer size?\n"); + return false; + } + + return true; +} + +static int load_verity_table(struct dm_ioctl *io, char *name, uint64_t device_size, int fd, + const struct verity_table_params *params, format_verity_table_func format) { char *verity_params; char *buffer = (char*) io; @@ -390,35 +295,32 @@ static int load_verity_table(struct dm_ioctl *io, char *name, uint64_t device_si struct dm_target_spec *tgt = (struct dm_target_spec *) &buffer[sizeof(struct dm_ioctl)]; - // set tgt arguments here + // set tgt arguments io->target_count = 1; - tgt->status=0; - tgt->sector_start=0; - tgt->length=device_size/512; + tgt->status = 0; + tgt->sector_start = 0; + tgt->length = device_size / 512; strcpy(tgt->target_type, "verity"); - // build the verity params here + // build the verity params verity_params = buffer + sizeof(struct dm_ioctl) + sizeof(struct dm_target_spec); bufsize = DM_BUF_SIZE - (verity_params - buffer); - if (mode == VERITY_MODE_EIO) { - // allow operation with older dm-verity drivers that are unaware - // of the mode parameter by omitting it; this also means that we - // cannot use logging mode with these drivers, they always cause - // an I/O error for corrupted blocks - strcpy(verity_params, table); - } else if (snprintf(verity_params, bufsize, "%s %d", table, mode) < 0) { + if (!format(verity_params, bufsize, params)) { + ERROR("Failed to format verity parameters\n"); return -1; } + INFO("loading verity table: '%s'", verity_params); + // set next target boundary verity_params += strlen(verity_params) + 1; - verity_params = (char*) (((unsigned long)verity_params + 7) & ~8); + verity_params = (char*)(((unsigned long)verity_params + 7) & ~8); tgt->next = verity_params - buffer; // send the ioctl to load the verity table if (ioctl(fd, DM_TABLE_LOAD, io)) { - ERROR("Error loading verity table (%s)", strerror(errno)); + ERROR("Error loading verity table (%s)\n", strerror(errno)); return -1; } @@ -703,28 +605,31 @@ out: static int compare_last_signature(struct fstab_rec *fstab, int *match) { char tag[METADATA_TAG_MAX_LENGTH + 1]; - char *signature = NULL; int fd = -1; int rc = -1; + off64_t offset = 0; + struct fec_handle *f = NULL; + struct fec_verity_metadata verity; uint8_t curr[SHA256_DIGEST_SIZE]; uint8_t prev[SHA256_DIGEST_SIZE]; - off64_t offset = 0; - uint64_t device_size; *match = 1; - // get verity filesystem size - if (get_fs_size(fstab->fs_type, fstab->blk_device, &device_size) < 0) { - ERROR("Failed to get filesystem size\n"); + if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE, + FEC_DEFAULT_ROOTS) == -1) { + ERROR("Failed to open '%s' (%s)\n", fstab->blk_device, + strerror(errno)); + return rc; + } + + // read verity metadata + if (fec_verity_get_metadata(f, &verity) == -1) { + ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device, + strerror(errno)); goto out; } - if (read_verity_metadata(device_size, fstab->blk_device, &signature, NULL) < 0) { - ERROR("Failed to read verity signature from %s\n", fstab->mount_point); - goto out; - } - - SHA256_hash(signature, RSANUMBYTES, curr); + SHA256_hash(verity.signature, RSANUMBYTES, curr); if (snprintf(tag, sizeof(tag), VERITY_LASTSIG_TAG "_%s", basename(fstab->mount_point)) >= (int)sizeof(tag)) { @@ -766,12 +671,7 @@ static int compare_last_signature(struct fstab_rec *fstab, int *match) rc = 0; out: - free(signature); - - if (fd != -1) { - close(fd); - } - + fec_close(f); return rc; } @@ -884,6 +784,7 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback) { alignas(dm_ioctl) char buffer[DM_BUF_SIZE]; bool use_state = true; + bool use_state_for_device = true; char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)]; char *mount_point; char propbuf[PROPERTY_VALUE_MAX]; @@ -928,10 +829,12 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback) continue; } + use_state_for_device = use_state; + if (use_state) { if (get_verity_state_offset(&fstab->recs[i], &offset) < 0 || read_verity_state(fstab->recs[i].verity_loc, offset, &mode) < 0) { - continue; + use_state_for_device = false; } } @@ -946,7 +849,7 @@ int fs_mgr_update_verity_state(fs_mgr_verity_state_callback callback) status = &buffer[io->data_start + sizeof(struct dm_target_spec)]; - if (use_state && *status == 'C') { + if (use_state_for_device && *status == 'C') { if (write_verity_state(fstab->recs[i].verity_loc, offset, VERITY_MODE_LOGGING) < 0) { continue; @@ -972,87 +875,105 @@ out: return rc; } -int fs_mgr_setup_verity(struct fstab_rec *fstab) { - +int fs_mgr_setup_verity(struct fstab_rec *fstab) +{ int retval = FS_MGR_SETUP_VERITY_FAIL; int fd = -1; - int mode; - - char *verity_blk_name = 0; - char *verity_table = 0; - char *verity_table_signature = 0; - int verity_table_length = 0; - uint64_t device_size = 0; + char *invalid_table = NULL; + char *verity_blk_name = NULL; + struct fec_handle *f = NULL; + struct fec_verity_metadata verity; + struct verity_table_params params; alignas(dm_ioctl) char buffer[DM_BUF_SIZE]; struct dm_ioctl *io = (struct dm_ioctl *) buffer; char *mount_point = basename(fstab->mount_point); - // get verity filesystem size - if (get_fs_size(fstab->fs_type, fstab->blk_device, &device_size) < 0) { + if (fec_open(&f, fstab->blk_device, O_RDONLY, FEC_VERITY_DISABLE, + FEC_DEFAULT_ROOTS) < 0) { + ERROR("Failed to open '%s' (%s)\n", fstab->blk_device, + strerror(errno)); return retval; } - // read the verity block at the end of the block device - // send error code up the chain so we can detect attempts to disable verity - retval = read_verity_metadata(device_size, - fstab->blk_device, - &verity_table_signature, - &verity_table); - if (retval < 0) { + // read verity metadata + if (fec_verity_get_metadata(f, &verity) < 0) { + ERROR("Failed to get verity metadata '%s' (%s)\n", fstab->blk_device, + strerror(errno)); goto out; } - retval = FS_MGR_SETUP_VERITY_FAIL; - verity_table_length = strlen(verity_table); +#ifdef ALLOW_ADBD_DISABLE_VERITY + if (verity.disabled) { + retval = FS_MGR_SETUP_VERITY_DISABLED; + INFO("Attempt to cleanly disable verity - only works in USERDEBUG\n"); + goto out; + } +#endif + + // read ecc metadata + if (fec_ecc_get_metadata(f, ¶ms.ecc) < 0) { + params.ecc.valid = false; + } + + params.ecc_dev = fstab->blk_device; // get the device mapper fd if ((fd = open("/dev/device-mapper", O_RDWR)) < 0) { - ERROR("Error opening device mapper (%s)", strerror(errno)); + ERROR("Error opening device mapper (%s)\n", strerror(errno)); goto out; } // create the device if (create_verity_device(io, mount_point, fd) < 0) { - ERROR("Couldn't create verity device!"); + ERROR("Couldn't create verity device!\n"); goto out; } // get the name of the device file if (get_verity_device_name(io, mount_point, fd, &verity_blk_name) < 0) { - ERROR("Couldn't get verity device number!"); + ERROR("Couldn't get verity device number!\n"); goto out; } - if (load_verity_state(fstab, &mode) < 0) { + if (load_verity_state(fstab, ¶ms.mode) < 0) { /* if accessing or updating the state failed, switch to the default * safe mode. This makes sure the device won't end up in an endless * restart loop, and no corrupted data will be exposed to userspace * without a warning. */ - mode = VERITY_MODE_EIO; + params.mode = VERITY_MODE_EIO; } // verify the signature on the table - if (verify_table(verity_table_signature, - verity_table, - verity_table_length) < 0) { - if (mode == VERITY_MODE_LOGGING) { + if (verify_table(verity.signature, verity.table, + verity.table_length) < 0) { + if (params.mode == VERITY_MODE_LOGGING) { // the user has been warned, allow mounting without dm-verity retval = FS_MGR_SETUP_VERITY_SUCCESS; goto out; } // invalidate root hash and salt to trigger device-specific recovery - if (invalidate_table(verity_table, verity_table_length) < 0) { + invalid_table = strdup(verity.table); + + if (!invalid_table || + invalidate_table(invalid_table, verity.table_length) < 0) { goto out; } + + params.table = invalid_table; + } else { + params.table = verity.table; } - INFO("Enabling dm-verity for %s (mode %d)\n", mount_point, mode); + INFO("Enabling dm-verity for %s (mode %d)\n", mount_point, params.mode); // load the verity mapping table - if (load_verity_table(io, mount_point, device_size, fd, verity_table, - mode) < 0) { + if (load_verity_table(io, mount_point, verity.data_size, fd, ¶ms, + format_verity_table) < 0 && + // try the legacy format for backwards compatibility + load_verity_table(io, mount_point, verity.data_size, fd, ¶ms, + format_legacy_verity_table) < 0) { goto out; } @@ -1081,8 +1002,8 @@ out: close(fd); } - free(verity_table); - free(verity_table_signature); + fec_close(f); + free(invalid_table); free(verity_blk_name); return retval; diff --git a/init/Android.mk b/init/Android.mk index c1cdc1ae9..8e45a7aaa 100644 --- a/init/Android.mk +++ b/init/Android.mk @@ -84,6 +84,8 @@ LOCAL_UNSTRIPPED_PATH := $(TARGET_ROOT_OUT_UNSTRIPPED) LOCAL_STATIC_LIBRARIES := \ libinit \ libfs_mgr \ + libfec \ + libfec_rs \ libsquashfs_utils \ liblogwrap \ libcutils \ @@ -94,6 +96,7 @@ LOCAL_STATIC_LIBRARIES := \ libc \ libselinux \ libmincrypt \ + libcrypto_static \ libc++_static \ libdl \ libsparse_static \