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Add adb enable-verity

Browse source 
Note that it is *easy* to break your phone with this feature. It is
not a bug that reenabling verity after changing one byte of the system
partition stops the device booting.

(cherry-pick of 7c442e1700e6312727283db402dec6f666f1b55a.)

Bug: 18529433
Change-Id: I632e91281884471a362960f1ba30312d2669b8ff
This commit is contained in:
Paul Lawrence 2014-12-03 15:31:57 -08:00 committed by Elliott Hughes
parent b471f5249b
commit 982089d838
6 changed files with 104 additions and 31 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
adb/Android.mk
View file

@ -110,7 +110,7 @@ LOCAL_SRC_FILES := \
jdwp_service.c \
framebuffer_service.c \
remount_service.c \
disable_verity_service.c \
set_verity_enable_state_service.c \
usb_linux_client.c
LOCAL_CFLAGS := \

4
adb/adb.h
View file

@ -328,8 +328,10 @@ int handle_forward_request(const char* service, transport_type ttype, char* seri
#if !ADB_HOST
void framebuffer_service(int fd, void *cookie);
// Allow enable-verity to write to system and vendor block devices
int make_system_and_vendor_block_devices_writable();
void remount_service(int fd, void *cookie);
void disable_verity_service(int fd, void* cookie);
void set_verity_enabled_state_service(int fd, void* cookie);
#endif
/* packet allocator */

6
adb/commandline.c
View file

@ -190,10 +190,11 @@ void help()
"\n"
" adb restore <file> - restore device contents from the <file> backup archive\n"
"\n"
" adb disable-verity - disable dm-verity checking on USERDEBUG builds\n"
" adb enable-verity - re-enable dm-verity checking on USERDEBUG builds\n"
" adb keygen <file> - generate adb public/private key. The private key is stored in <file>,\n"
" and the public key is stored in <file>.pub. Any existing files\n"
" are overwritten.\n"
" adb disable-verity - disable dm-verity checking on USERDEBUG builds\n"
" adb help - show this help message\n"
" adb version - show version num\n"
"\n"
@ -1446,7 +1447,8 @@ top:
if(!strcmp(argv[0], "remount") || !strcmp(argv[0], "reboot")
|| !strcmp(argv[0], "reboot-bootloader")
|| !strcmp(argv[0], "tcpip") || !strcmp(argv[0], "usb")
|| !strcmp(argv[0], "root") || !strcmp(argv[0], "disable-verity")) {
|| !strcmp(argv[0], "root") || !strcmp(argv[0], "disable-verity")
|| !strcmp(argv[0], "enable-verity")) {
char command[100];
if (!strcmp(argv[0], "reboot-bootloader"))
snprintf(command, sizeof(command), "reboot:bootloader");

67
adb/remount_service.c
View file

@ -79,29 +79,57 @@ static int hasVendorPartition()
return false;
}
static int make_block_device_writable(const char* dir)
{
char *dev = 0;
int fd = -1;
int OFF = 0;
int rc = -1;
dev = find_mount(dir);
if (!dev)
goto errout;
fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
if (fd < 0)
goto errout;
if (ioctl(fd, BLKROSET, &OFF)) {
goto errout;
}
rc = 0;
errout:
if (fd >= 0) {
adb_close(fd);
}
if (dev) {
free(dev);
}
return rc;
}
/* Init mounts /system as read only, remount to enable writes. */
static int remount(const char* dir, int* dir_ro)
{
char *dev;
int fd;
int OFF = 0;
if (dir_ro == 0) {
return 0;
}
if (make_block_device_writable(dir)) {
return -1;
}
dev = find_mount(dir);
if (!dev)
return -1;
fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
if (fd < 0)
return -1;
ioctl(fd, BLKROSET, &OFF);
adb_close(fd);
*dir_ro = mount(dev, dir, "none", MS_REMOUNT, NULL);
free(dev);
@ -114,6 +142,28 @@ static void write_string(int fd, const char* str)
writex(fd, str, strlen(str));
}
int make_system_and_vendor_block_devices_writable(int fd)
{
char buffer[200];
if (make_block_device_writable("/system")) {
snprintf(buffer, sizeof(buffer),
"Failed to make system block device writable %s\n",
strerror(errno));
write_string(fd, buffer);
return -1;
}
if (hasVendorPartition() && make_block_device_writable("/vendor")) {
snprintf(buffer, sizeof(buffer),
"Failed to make vendor block device writable: %s\n",
strerror(errno));
write_string(fd, buffer);
return -1;
}
return 0;
}
void remount_service(int fd, void *cookie)
{
char buffer[200];
@ -167,4 +217,3 @@ void remount_service(int fd, void *cookie)
adb_close(fd);
}

4
adb/services.c
View file

@ -472,7 +472,9 @@ int service_to_fd(const char *name)
}
}
} else if(!strncmp(name, "disable-verity:", 15)) {
ret = create_service_thread(disable_verity_service, NULL);
ret = create_service_thread(set_verity_enabled_state_service, (void*)0);
} else if(!strncmp(name, "enable-verity:", 15)) {
ret = create_service_thread(set_verity_enabled_state_service, (void*)1);
#endif
}
if (ret >= 0) {

52
adb/disable_verity_service.c → adb/set_verity_enable_state_service.c
View file

@ -78,11 +78,13 @@ static int get_target_device_size(int fd, const char *blk_device,
return 0;
}
static int disable_verity(int fd, const char *block_device,
const char* mount_point)
/* Turn verity on/off */
static int set_verity_enabled_state(int fd, const char *block_device,
const char* mount_point, bool enable)
{
uint32_t magic_number;
const uint32_t voff = VERITY_METADATA_MAGIC_DISABLE;
const uint32_t new_magic = enable ? VERITY_METADATA_MAGIC_NUMBER
: VERITY_METADATA_MAGIC_DISABLE;
uint64_t device_length;
int device;
int retval = -1;
@ -114,12 +116,18 @@ static int disable_verity(int fd, const char *block_device,
goto errout;
}
if (magic_number == VERITY_METADATA_MAGIC_DISABLE) {
if (!enable && magic_number == VERITY_METADATA_MAGIC_DISABLE) {
write_console(fd, "Verity already disabled on %s\n", mount_point);
goto errout;
}
if (magic_number != VERITY_METADATA_MAGIC_NUMBER) {
if (enable && magic_number == VERITY_METADATA_MAGIC_NUMBER) {
write_console(fd, "Verity already enabled on %s\n", mount_point);
goto errout;
}
if (magic_number != VERITY_METADATA_MAGIC_NUMBER
&& magic_number != VERITY_METADATA_MAGIC_DISABLE) {
write_console(fd,
"Couldn't find verity metadata at offset %"PRIu64"!\n",
device_length);
@ -132,13 +140,17 @@ static int disable_verity(int fd, const char *block_device,
goto errout;
}
if (adb_write(device, &voff, sizeof(voff)) != sizeof(voff)) {
write_console(fd, "Could not set verity disabled flag on device %s\n",
block_device);
if (adb_write(device, &new_magic, sizeof(new_magic)) != sizeof(new_magic)) {
write_console(fd, "Could not set verity %s flag on device %s with error %s\n",
enable ? "enabled" : "disabled",
block_device,
strerror(errno));
goto errout;
}
write_console(fd, "Verity disabled on %s\n", mount_point);
write_console(fd, "Verity %s on %s\n",
enable ? "enabled" : "disabled",
mount_point);
retval = 0;
errout:
if (device != -1)
@ -146,13 +158,14 @@ errout:
return retval;
}
void disable_verity_service(int fd, void* cookie)
void set_verity_enabled_state_service(int fd, void* cookie)
{
bool enable = (cookie != NULL);
#ifdef ALLOW_ADBD_DISABLE_VERITY
char fstab_filename[PROPERTY_VALUE_MAX + sizeof(FSTAB_PREFIX)];
char propbuf[PROPERTY_VALUE_MAX];
int i;
bool any_disabled = false;
bool any_changed = false;
property_get("ro.secure", propbuf, "0");
if (strcmp(propbuf, "1")) {
@ -162,7 +175,7 @@ void disable_verity_service(int fd, void* cookie)
property_get("ro.debuggable", propbuf, "0");
if (strcmp(propbuf, "1")) {
write_console(fd, "verity cannot be disabled - USER build\n");
write_console(fd, "verity cannot be disabled/enabled - USER build\n");
goto errout;
}
@ -176,22 +189,27 @@ void disable_verity_service(int fd, void* cookie)
goto errout;
}
if (enable && make_system_and_vendor_block_devices_writable(fd)) {
goto errout;
}
/* Loop through entries looking for ones that vold manages */
for (i = 0; i < fstab->num_entries; i++) {
if(fs_mgr_is_verified(&fstab->recs[i])) {
if (!disable_verity(fd, fstab->recs[i].blk_device,
fstab->recs[i].mount_point)) {
any_disabled = true;
if (!set_verity_enabled_state(fd, fstab->recs[i].blk_device,
fstab->recs[i].mount_point, enable)) {
any_changed = true;
}
}
}
if (any_disabled) {
if (any_changed) {
write_console(fd,
"Now reboot your device for settings to take effect\n");
}
#else
write_console(fd, "disable-verity only works for userdebug builds\n");
write_console(fd, "%s-verity only works for userdebug builds\n",
disabling ? "disable" : "enable");
#endif
errout: