Abstract:
A secure method for updating computer firmware online is described. The firmware storage locations are write protected prior to loading the operating system. Updating the firmware after loading the operating system helps to reduce downtime.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to the field of updating computer system firmware in a secure environment. More particularly, the present invention relates to an efficient method of performing secure firmware updates in a computer system while an operating system is running.  
         BACKGROUND OF THE INVENTION  
         [0002]    In a computer system, an operating system (OS) performs functions such as scheduling application programs and resolving conflicts among applications that request access to the same resources. Moreover, operating systems communicate service requests from application programs to the hardware device drivers. Operating system examples include WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT, and LINUX.  
           [0003]    Firmware is a set of hardware setup programs. Firmware is typically stored in flash memory or read only memory. Firmware includes programs that are somewhat analogous to device drivers, which are used to activate the hardware of a standard computer system. A computer may include hardware for performing operations such as reading keystrokes from a keyboard, transmitting information to a video display, or sending information to a printer.  
           [0004]    [0004]FIG. 1 depicts a flowchart of a firmware update process. The process begins in operation  100  with a firmware update request. Once the process is initiated, the OS is shut down in operation  110 . The system is then rebooted in operation  120 . Following reboot, a Basic Input/Output System (BIOS) Power On Self-Test (POST) diagnostic that performs hardware tests is executed in operation  130 . After DOS or an equivalent OS is booted in operation  135 , the firmware update utility is then executed in operation  140  in order to update the firmware. The system is then rebooted again in operation  150 . The POST code is run again in operation  160 . Finally, the operation system and computer system applications are loaded in operation  170 .  
           [0005]    Because updating firmware requires that the system be shutdown and rebooted, the process can take as long as  10  minutes. The firmware update process takes even longer for multiple systems connected to a network since each system is serially updated. In addition, because the memory used to store firmware is typically not write protected, firmware is susceptible to tampering.  
           [0006]    Other systems update the firmware after the operating system is running. These systems typically utilize System Management Interrupts (SMI) while the OS is running. SMI works fine under desktop operating systems such as WINDOWS 95 and WINDOWS 98, but causes instability under multiprocessor operating systems like WINDOWS 2000 and WINDOWS NT. Moreover, SMI is incompatible with Intel® ITANIUM processor family platforms. Thus, a secure method to perform computer system updates on Intel® ITANIUM processor family platforms and desktop and multiprocessor operating systems would be desirable.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The embodiments of the present invention are illustrated by way of example and not in the figures of the accompanying drawings, in which like references indicate similar elements and in which:  
         [0008]    [0008]FIG. 1 shows a flowchart of a prior art firmware update process;  
         [0009]    [0009]FIG. 2 shows a bock diagram for one embodiment of the invention of a computer system that performs secure firmware updates;  
         [0010]    [0010]FIG. 3 shows a block diagram for one embodiment of the invention of a circuit for allowing more than one component to select the active storage area;  
         [0011]    [0011]FIG. 4 shows a block diagram for one embodiment of the invention of a computer system connected to a local area network that performs secure firmware updates; and  
         [0012]    [0012]FIG. 5 shows a flowchart for one embodiment of the invention of a firmware update process under an operating system presence.  
     
    
     DETAILED DESCRIPTION  
       [0013]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.  
         [0014]    The BIOS program is a set of routines used by a computer system to enable communication between a computer processor and input/output devices. BIOS is updated to correct program errors or to add new features such as support for new industry standards or customer specific features. For one embodiment of the invention, the BIOS program is updated under the presence of an OS such as WINDOWS 95, WINDOWS 98, WINDOWS 2000, or WINDOWS NT. In other words, a new BIOS is loaded after the OS is booted. SMI is not used in the firmware update process to avoid instability in multiprocessor operating systems and in Intel® ITANIUM processor family platforms.  
         [0015]    [0015]FIG. 2 depicts an example of a computer system to perform secure BIOS updates. The computer system of FIG. 2 can also be used to perform other firmware updates as well. For this embodiment of the invention, central processing unit, CPU  210 , is coupled to a chipset  230  through bus  215 . The computer system, however, is not limited to having one central processing unit. The computer system may have a plurality of central processing units coupled to the chipset  230 . The chipset  230  allows computer components to communicate with the central processing unit(s). Commercially available chipsets include Intel® 815E, Intel® 820E, and Intel® 850. The components of FIG. 2 are coupled to the chipset  230  through bus  235  and bus  265  respectively. Responsibilities of chipset  230  may include efficient data transfers, bus support, and advanced power management features.  
         [0016]    For one embodiment of the invention, the firmware storage area  270  is flash memory. Flash memory is usually organized as multiple physical blocks. For this embodiment of the invention, the flash memory is at least twice the size of the system BIOS image. The firmware storage area  270  may be divided into two areas, memory storage area  272  and memory storage area  274 . Each of the memory storage areas  272  and  274  may contain multiple physical blocks. The memory storage areas  272  and  274  are also termed active storage area and staged storage area, depending on whether memory storage area  272  or memory storage area  274  is selected by the chipset  230  for its source of BIOS. The selected memory storage area is the active storage area, while the non-selected storage area is the staged storage area.  
         [0017]    The firmware stored in the active storage area is executed upon system startup or reset. In contrast, the firmware in the staged storage area is not executed upon system startup or reset. The staged storage area is instead used to store any firmware updates. Firmware updates to the staged storage area may be performed by an OS driver under OS presence. For one embodiment of the invention, the entire BIOS program is updated to correct software code errors. For another embodiment of the invention, the entire BIOS program is updated to add new system features. For yet another embodiment of the invention, a portion of the BIOS program is updated.  
         [0018]    Each block of the firmware storage area  270  may be locked down and write protected. Once a block is locked down and write protected, write protection cannot be removed under software control. Thus, after lock down, there is no mechanism that allows update or erase operations to be performed on the firmware storage area  270 . The blocks in memory storage area  272  and memory storage area  274  are capable of being independently configured for lock down. During normal system operation, the active storage area is locked down. The staged storage area, however, may also be locked down after firmware updates are performed.  
         [0019]    Lock down is only removed by a special control signal applied to the firmware storage area  270 . This control signal may be connected to a system-wide control signal. The system-wide control signal forces the processor to execute code from the active storage area. Processor reset or initialization signals are examples of the system-wide control signal. As a result, the lock down remains in effect until the control signal is applied.  
         [0020]    The mechanism for selecting the active storage area may be a general purpose input/output (GPIO) signal. The chipset  230  may transmit the signal to select the active storage area to the firmware storage area  270  through the GPIO signal. For one embodiment of the invention, the GPIO signal is transmitted from the chipset  230  through a nonvolatile bit  260 . Thus, in the event of a complete power failure to the computer system, the state of the GPIO bit  260  is restored to its pre-power fail condition once the power is restored. It is also important for security purposes that the mechanism for generating the GPIO signal is capable of being locked down or write protected. Otherwise, BIOS is susceptible to tampering. Once the mechanism is write protected, it remains so until a system initialization or reset signal is asserted.  
         [0021]    For another embodiment of the invention, the GPIO bit  260  may be implemented in a Super Input/Output (SIO) device. The SIO contains embedded functions and provides a means of communication to other devices through the chipset  230 .  
         [0022]    For yet another embodiment, the hardware mechanism for selecting the active storage area may be generated by more than one component of the system. Any component that is to be used for selecting the active storage area may be secured through lock down or write protection. For instance, the chipset  230  is described above as having the ability to lock down the mechanism for generating the GPIO signal.  
         [0023]    An Intelligent Platform Management Interface (IPMI) compliant baseboard management controller (BMC) is one example of an alternative component to select the active storage area. The BMC is an embedded micro-controller that provides an external communications mechanism for the system. For instance, the BMC may act as an interface to a local area network, a wireless system, or a telephone system. The BMC code is capable of being locked down.  
         [0024]    For yet another embodiment of the invention, both the GPIO bit and the BMC may be used to select the active storage area of the firmware storage area  270 . FIG. 3 depicts an example of a circuit that allows multiple components to select the active storage area. In this example, the GPIO bit  260  is coupled to an input of a XOR combinational logic gate  330 . A nonvolatile bit  320  is coupled to another input of the XOR gate  330 . The signal of the nonvolatile bit is supplied by a BMC  310 . The output signal of the XOR gate  330  then selects the active storage area of the firmware storage area  270 .  
         [0025]    As an example, memory storage area  272  may be selected as the active storage area if the output signal of the XOR gate  330  is asserted high. By default, the memory storage area  274  is the staged storage area. Conversely, memory storage area  274  is selected as the active storage area and memory storage area  272  the staged storage area if the output signal of the XOR gate  330  is asserted low. Therefore, the active storage area will be altered only if one of the input signals from the GPIO bit  260  or nonvolatile bit  320  is different from its previous state.  
         [0026]    [0026]FIG. 4 depicts an embodiment of the invention of a computer system connected to a local area network that performs secure firmware updates. The computer system may have three central processing units: CPU  405 , CPU  410 , and CPU  420 . The central processing units are coupled to the chipset  430  through the bus  415 . The chipset  430  may also be coupled to components such as main memory  440 , BMC  450 , and firmware storage area  470  through bus  435 , bus  455 , and bus  465  respectively. The firmware storage area  470  comprises an active storage area  472  and a staged storage area  474 . The BMC  450  is also coupled to a local area network interface  480 .  
         [0027]    For a system connected to a local area network, the BMC  450  may be sent new firmware images through the system local area network interface  480 . For one embodiment of the invention, the local area network interface  480  receives new firmware images as total cost of ownership (TCO) packets. The BMC  450  takes the TCO packets and strips out the firmware address and data information. The BMC  450  then writes the BIOS image to the firmware storage area  470  through the chipset  430  through a SIO  460 . For another embodiment of the invention, the BMC  450  communicates directly with the firmware storage area  470  without having to access the chipset  430 . For yet another embodiment of the invention, a driver running under the OS updates the firmware storage area  470  directly without using the BMC  450 .  
         [0028]    Using the BMC  450  to perform firmware updates provides flexibility because it removes the need for an operating system specific firmware storage area driver to be run. Therefore, new firmware may be loaded to the firmware storage area  470  without the intervention of an operating system. In addition, distributing firmware updates using the BMC  450  and TCO packets over a local area network allows many systems to be updated simultaneously. For example, a data center having hundreds of identical systems may update all of its systems using a batch process.  
         [0029]    [0029]FIG. 5 depicts an example of a flowchart of the process for checking for new image and controlling BIOS in a computer system. The flowchart of FIG. 5, however, is not limited to updating BIOS and may be used for updating other firmwares of a computer system. The user initiates the process of operation  500  to update BIOS by resetting the system. The BIOS Power On Self-Test is then begun from the firmware active storage area in operation  505 . In operation  510 , the firmware staged storage area is checked for a BIOS image. If an image is found in the staged storage area, operation  515  then checks whether the image in the staged storage area is newer than the code in the active storage area. Operation  515  may be performed by comparing the time and date stamp of the program codes stored in the active storage area and the staged storage area.  
         [0030]    If a newer image is detected, the image in the staged storage area is authenticated in operation  520 . Authentication is performed by comparing the firmware program stored in the active area with authentication information stored or loaded to the system. For one embodiment of the invention, the authentication information is saved to the staged storage area. The level of scrutiny in an authentication check is flexible and may range from a simple check sum to a detailed digital signature comparison. If the image in the staged storage area is determined to be authentic, then the active storage area is switched with the staged storage area and a system reset is generated in operation  530 .  
         [0031]    As an example, the memory storage area  272  may be the active storage area. Thus, after a system reset, the firmware is read from memory storage area  272  in operation  505 . The staged storage area is checked in operation  510 . If a newer image is detected in operation  515  and the firmware stored in the staged storage area, memory storage area  272 , is authenticated in operation  520 , the active storage area is switched. Switching the active storage area in this case involves selecting memory storage area  274  as the active storage area and making memory storage area  272  the staged storage area. A system reset is generated in operation  530  before BIOS, including the POST program, is accessed from the new active storage area.  
         [0032]    However, the operation  530  of switching the staged storage area with the active storage area is not performed unless both a newer image and an authentic image were detected in the staged storage area in operations  515  and  520  respectively. If a newer image or an authentic image is not detected, the POST program is executed from the current active storage area in operation  535 . In other words, the staged storage area and the active storage area are left untouched and the POST program is executed with the code found in the active storage area.  
         [0033]    Next, in operation  540 , the firmware active storage area is secured by making it write protected. For example, the system BIOS may write protect and lock down the blocks containing active BIOS. The mechanism for allowing write and read operations to select the active storage area is also secured before any unknown software can be loaded. The mechanism is secured when the mechanism is prevented from changing states. At this time, the operating system may be loaded in operation  545 . Loading the operating system  545  or any other software code is the process of accessing the code from memory and then executing the code. After the OS is loaded, the staged storage area is updated with the new BIOS code in operation  550 . Thus, the BIOS code is updated under OS presence.  
         [0034]    Authentication information may be stored in the staged storage area at the same time that the new BIOS code is saved. The new BIOS code is then executed only after the OS is shutdown in operation  555  and the system is rebooted. The OS shutdown may be prompted by the user or may be a scheduled maintenance task.  
         [0035]    Postponing the BIOS update until a scheduled OS downtime allows the BIOS update to be performed at an opportune time for the user rather than forcing a shutdown and reboot as soon as a BIOS update is made. As previously stated, shutdown and reboot typically creates potentially significant delays. In addition, by write protecting the active storage area and locking down the hardware mechanism that selects the active storage area, the BIOS update process is performed under a secure environment.  
         [0036]    For another embodiment of the invention, the operation  520  of authenticating the image is not performed. Instead, if a newer image is detected in operation  515 , the active storage area is immediately switched in operation  530 . If a newer image is not detected, the POST code is executed in operation  535 .  
         [0037]    For yet another embodiment of the invention, the operation  515  of checking for a newer image is not performed. The system authenticates the image stored in the staged storage area in operation  520  if a firmware image is detected in the staged storage area in operation  510 . If an authentic image is detected in operation  520 , the active storage area is switched in operation  530 . The switching process selects the former active storage area as the new staged storage area and conversely, the former staged storage area becomes the new active storage area. If an authentic image is not detected, the active storage area and the staged storage area remain unchanged. The previous image stored in the staged storage area is then erased.  
         [0038]    For yet another embodiment of the invention, a “watchdog timer” is coupled to the firmware storage area  270  and may initiate the switching of the active storage area. The watchdog timer monitors the execution of firmware code. If the execution of firmware code takes longer than a predetermined period of time, the watchdog timer times out and switches the active storage area. The watchdog timer then initiates a system reset. After reset, the firmware is read from the new active storage area.  
         [0039]    Embodiments of the present invention may be implemented in hardware or software, or a combination of both. However, preferably, embodiments of the invention may be implemented in computer programs executing on programmable computer systems each comprising at least one processor, a data storage system (including volatile and nonvolatile memory and/or storage elements), at least one input device, and at least one output device. Program code may be applied to input data to perform the functions described herein and generate output information. The output information may be applied to one or more output devices, in known fashion.  
         [0040]    Each program may be implemented in a high level procedural or object oriented programming language to communicate with the computer system. However, the programs may be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language.  
         [0041]    Each such computer program may be stored on a storage media or device (e.g., hard disk drive, floppy disk drive, read only memory (ROM), CD-ROM device, flash memory device, digital versatile disk (DVD), or other storage device) readable by a general or special purpose programmable computer system, for configuring and operating the computer system when the storage media or device is read by the computer system to perform the procedures described herein. Embodiments of the invention may also be considered to be implemented as a machine-readable storage medium, configured for use with a computer system, where the storage medium so configured causes the computer system to operate in a specific and predefined manner to perform the functions described herein.  
         [0042]    In the foregoing specification the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modification and changes may be made thereto without departure from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense.