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Mount system as read-only by default

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Mounting system as rw can prevent future OTA updates. The purpose
of this patch set is to prevent TWRP from mounting sytem as rw on
the first boot. Device maintainers should update their twrp.fstab
files on these devices to include an additional line:
/system_image emmc /dev/block/../system

This line will allow TWRP to create a raw system image backup to
ensure that the user can return to an original state for future
OTA updates.

Change-Id: I8929d85bc3a5b96cc564bc7f734b58d5612ec833
This commit is contained in:
Ethan Yonker
2015-05-27 09:22:49 -05:00
parent f746dbb054
commit eb32b1ff00
13 changed files with 459 additions and 7 deletions
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partition.cpp
+52 -4
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@@ -155,6 +155,7 @@ TWPartition::TWPartition() {
Crypto_Key_Location = "footer";
MTP_Storage_ID = 0;
Can_Flash_Img = false;
Mount_Read_Only = false;
}
TWPartition::~TWPartition(void) {
@@ -258,6 +259,7 @@ bool TWPartition::Process_Fstab_Line(string Line, bool Display_Error) {
Storage_Name = Display_Name;
Wipe_Available_in_GUI = true;
Can_Be_Backed_Up = true;
Mount_Read_Only = true;
} else if (Mount_Point == "/data") {
UnMount(false); // added in case /data is mounted as tmpfs for qcom hardware decrypt
Display_Name = "Data";
@@ -390,6 +392,11 @@ bool TWPartition::Process_Fstab_Line(string Line, bool Display_Error) {
Display_Name = "Recovery";
Backup_Display_Name = Display_Name;
Can_Flash_Img = true;
} else if (Mount_Point == "/system_image") {
Display_Name = "System Image";
Backup_Display_Name = Display_Name;
Can_Flash_Img = false;
Can_Be_Backed_Up = true;
}
}
@@ -936,6 +943,7 @@ bool TWPartition::Is_Mounted(void) {
bool TWPartition::Mount(bool Display_Error) {
int exfat_mounted = 0;
unsigned long flags = Mount_Flags;
if (Is_Mounted()) {
return true;
@@ -964,9 +972,15 @@ bool TWPartition::Mount(bool Display_Error) {
#endif
}
}
if (Mount_Read_Only)
flags |= MS_RDONLY;
if (Fstab_File_System == "yaffs2") {
// mount an MTD partition as a YAFFS2 filesystem.
const unsigned long flags = MS_NOATIME | MS_NODEV | MS_NODIRATIME;
flags = MS_NOATIME | MS_NODEV | MS_NODIRATIME;
if (Mount_Read_Only)
flags |= MS_RDONLY;
if (mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), Fstab_File_System.c_str(), flags, NULL) < 0) {
if (mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), Fstab_File_System.c_str(), flags | MS_RDONLY, NULL) < 0) {
if (Display_Error)
@@ -1008,8 +1022,8 @@ bool TWPartition::Mount(bool Display_Error) {
mount_fs = "texfat";
if (!exfat_mounted &&
mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), mount_fs.c_str(), Mount_Flags, Mount_Options.c_str()) != 0 &&
mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), mount_fs.c_str(), Mount_Flags, NULL) != 0) {
mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), mount_fs.c_str(), flags, Mount_Options.c_str()) != 0 &&
mount(Actual_Block_Device.c_str(), Mount_Point.c_str(), mount_fs.c_str(), flags, NULL) != 0) {
#ifdef TW_NO_EXFAT_FUSE
if (Current_File_System == "exfat") {
LOGINFO("Mounting exfat failed, trying vfat...\n");
@@ -1018,7 +1032,7 @@ bool TWPartition::Mount(bool Display_Error) {
LOGERR("Unable to mount '%s'\n", Mount_Point.c_str());
else
LOGINFO("Unable to mount '%s'\n", Mount_Point.c_str());
LOGINFO("Actual block device: '%s', current file system: '%s', flags: 0x%8x, options: '%s'\n", Actual_Block_Device.c_str(), Current_File_System.c_str(), Mount_Flags, Mount_Options.c_str());
LOGINFO("Actual block device: '%s', current file system: '%s', flags: 0x%8x, options: '%s'\n", Actual_Block_Device.c_str(), Current_File_System.c_str(), flags, Mount_Options.c_str());
return false;
}
} else {
@@ -2138,3 +2152,37 @@ bool TWPartition::Flash_Image_FI(string Filename) {
TWFunc::Exec_Cmd(Command);
return true;
}
void TWPartition::Change_Mount_Read_Only(bool new_value) {
Mount_Read_Only = new_value;
}
int TWPartition::Check_Lifetime_Writes() {
bool original_read_only = Mount_Read_Only;
int ret = 1;
Mount_Read_Only = true;
if (Mount(false)) {
Find_Actual_Block_Device();
string block = basename(Actual_Block_Device.c_str());
string file = "/sys/fs/" + Current_File_System + "/" + block + "/lifetime_write_kbytes";
string result;
if (TWFunc::Path_Exists(file)) {
if (TWFunc::read_file(file, result) != 0) {
LOGINFO("Check_Lifetime_Writes of '%s' failed to read_file\n", file.c_str());
} else {
LOGINFO("Check_Lifetime_Writes result: '%s'\n", result.c_str());
if (result == "0") {
ret = 0;
}
}
} else {
LOGINFO("Check_Lifetime_Writes file does not exist '%s'\n", file.c_str());
}
UnMount(true);
} else {
LOGINFO("Check_Lifetime_Writes failed to mount '%s'\n", Mount_Point.c_str());
}
Mount_Read_Only = original_read_only;
return ret;
}