Mechanism to support writing files into a file system mounted in a secure memory device
A system, method and apparatus to record a file in a file system that is mounted in a secure section of a memory device. The memory device authenticates a requester to write data into secure section based on whether the requester is in possession of a cryptographic key. Nonprivileged modules of the operation system can write into a nonsecure section of the memory device. Requests to write or change a file can be recorded by nonprivileged modules into the nonsecure section for subsequent committing into the file system. In response to a request to commit the file, a security manager having the cryptographic key is called to identify, based on the records in the nonsecure section, data eligible to be written into the secure section. The security manager can generate commands, signed using the cryptographic key, to write the content of the file into the secure memory section.
1. A method, comprising:
mounting a file system into a secure memory region in a memory device configured to authenticate commands of writing data into the secure memory region based on a cryptographic key;
sending first commands to the memory device to write data into the file system;
determining that the first commands fail authentication based on the cryptographic key;
storing records of the first commands in a non-secure memory region of the memory device; and
in response to a request to commit a file in the file system,
determining, based on the records stored in the non-secure memory region, file data to be committed for the file in the file system mounted in the secure memory region; and
generating second commands to write the file data into the secure memory region based on the cryptographic key.
2. The method of claim 1 , wherein the first commands have no digital signatures; and the second commands have digital signatures signed using the cryptographic key.
3. The method of claim 2 , further comprising:
opening a recording session for the file in the file system, wherein the first commands are recorded in the non-secure memory region in response to the recording session being active.
4. The method of claim 3 , further comprising:
closing the recording session, wherein the request to commit the file is in response to the closing of the recording session.
5. The method of claim 4 , further comprising:
determining storage locations in the secure memory region allocated to store content of the file;
wherein the second commands are based on the storage locations.
6. The method of claim 5 , further comprising:
generating one or more third commands to write meta data of the file system based on the cryptographic key, the meta data identifying the storage locations of the content of the file.
7. The method of claim 5 , wherein the first commands include an identification of the file in the file system; and wherein the identification is independent of a storage location of the content of the file.
8. The method of claim 5 , further comprising:
receiving requests in an operating system to generate the first commands, wherein the operating system is not in possession of the cryptographic key; and
calling, by the operating system, a security manager to commit the file in the file system, wherein the security manager is in possession of the cryptographic key.
9. The method of claim 8 , further comprising:
loading instructions of the security manager from the secure memory region for execution at a boot time of the operating system.
10. The method of claim 9 , further comprising:
configuring, during the boot time, the security manager with the cryptographic key to authorize the security manager to write data into the secure memory region.
11. A memory device, comprising:
a secure memory region and a non-secure memory region;
a controller configured to authenticate commands of writing data into the secure memory region based on a cryptographic key;
wherein in response to first commands received in the controller to write data into a file system mounted in the secure memory region and the first commands failing authentication based on the cryptographic key, the controller is configured to store records of the first commands in the non-secure memory region; and
wherein in response to a request to commit a file in the file system, and identification of, based on the records stored in the non-secure memory region, file data to be committed for the file in the file system mounted in the secure memory region, the controller is configured to write the file data into the secure memory region.
12. The memory device of claim 11 , wherein the file data is written into the secure memory region via executing second commands generated based on the cryptographic key; and
wherein the first commands have no digital signatures; and the second commands have digital signatures signed using the cryptographic key.
13. The memory device of claim 12 , wherein the controller is further configured to:
executing the second commands to store content of the file at storage locations in the secure memory region; and
executing one or more third commands to write meta data of the file system based on the cryptographic key, the meta data identifying the storage locations of the content of the file.
14. The memory device of claim 13 , wherein the records of the first commands include an identification of the file in the file system; and wherein the identification of the file is independent of a storage location of the content of the file.
15. The memory device of claim 14 , wherein the controller is further configured to, at a boot time of an operating system of a computing system having the memory device, load instructions of a security manager from the secure memory region for execution, the instructions executable to generate the second commands.
16. The memory device of claim 15 , wherein the controller is further configured to, during the boot time, provide the security manager with the cryptographic key to authorize the security manager to write data into the secure memory region.
17. A non-transitory computer storage medium storing instructions which when, executed in a computing system having a memory device with a secure memory region mounted therein a file system and a non-secure memory region, cause the computing system to perform a method, the method comprising:
receiving a request to commit a file in the file system;
reading records of first commands in the non-secure memory region of the memory device, the first commands configured to write data into the file system mounted in the secure memory region;
determining, based on the records, file data to be committed for the file in the file system mounted in the secure memory region; and
generating second commands to write the file data into the secure memory region based on a cryptographic key, wherein the memory device is configured to authenticate commands of writing data into the secure memory region based on the cryptographic key.
18. The non-transitory computer storage medium of claim 17 , wherein the first commands have no digital signatures; and the second commands have digital signatures signed using the cryptographic key; and the method further comprises:
opening a recording session for the file in the file system, wherein the first commands are recorded in the non-secure memory region in response to the recording session being active; and
closing the recording session, wherein the request to commit the file is in response to the closing of the recording session.
19. The non-transitory computer storage medium of claim 18 , wherein the method further comprises:
determining storage locations in the secure memory region allocated to store content of the file, wherein the second commands are based on the storage locations; and
generating one or more third commands to write meta data of the file system based on the cryptographic key, the meta data identifying the storage locations of the content of the file.
20. The non-transitory computer storage medium of claim 19 , wherein the first commands include an identification of the file in the file system; wherein the identification is independent of a storage location of the content of the file; and
wherein the method further comprises:
receiving requests in an operating system to generate the first commands, wherein the operating system is not in possession of the cryptographic key;
wherein the request is received from the operating system to commit the file in the file system.