Method and system for facilitating replacement of system calls

1. A method, comprising:

modifying, prior to run time, an executable file of an application to cause an operating system loader to load additional code using a dynamically-linked library, wherein modifying the executable file comprises:

determining that the executable file includes insufficient unused space to accommodate a load command; and

adding the load command to the executable file by: identifying unused space outside of a data portion of the executable file that can be used to accommodate the load command;

wherein the additional code, when executed by a processor, causes the processor to change a pointer in a table that indicates an address of an imported function implementing a system call so that the pointer indicates an address of a customized function.

2. The method of claim 1 , wherein the customized function provides network communications through a secure network connection.

3. The method of claim 1 , wherein the customized function provides data encryption functionality.

4. The method of claim 1 , further comprising:

receiving, at the application, a policy communicated through an inter-process communication mechanism, wherein the customized function provides functionality in accordance with the policy.

5. The method of claim 1 , wherein the system call comprises a call to a libc library.

6. The method of claim 1 , wherein adding the load command to the executable file includes, responsive to the executable file including insufficient unused space, moving a portion of the executable file to make space for the load command.

7. The method of claim 1 , further comprising computing a new signature for the executable file and replacing an existing signature in the executable file with the new signature.

8. A non-transitory computer readable storage medium storing instructions that when executable by a processor cause the processor to:

modify, prior to run time, an executable file of an application to cause an operating system loader to load additional code using a dynamically-linked library, wherein modifying the executable file comprises:

determining that the executable file includes insufficient unused space to accommodate a load command; and

adding the load command to the executable file by: identifying unused space outside of a data portion of the executable file that can be used to accommodate the load command;

wherein the additional code, when executed, causes a change to a pointer in a table that indicates an address of an imported function implementing a system call so that the pointer indicates an address of a customized function.

9. The non-transitory computer readable storage medium of claim 8 , wherein the customized function provides network communications through a secure network connection.

10. The non-transitory computer readable storage medium of claim 8 , wherein the customized function provides data encryption functionality.

11. The non-transitory computer readable storage medium of claim 8 , further comprising instructions that, when executed by the processor, cause the processor to:

receive, at the application, a policy communicated through an inter-process communication mechanism, wherein the customized function provides functionality in accordance with the policy.

12. The non-transitory computer readable storage medium of claim 8 , wherein the system call comprises a call to a libc library.

13. The non-transitory computer readable storage medium of claim 8 , wherein adding the load command to the executable file further includes, responsive to the executable file including insufficient unused space, move a portion of the executable file to make space for the load command.

14. The non-transitory computer readable storage medium of claim 8 , further comprising instructions that, when executed by the processor, cause the processor to:

compute a new signature for the executable file and replacing an existing signature in the executable file with the new signature.

15. A computing system, comprising:

a processor; and

a storage device coupled to the processor storing instructions that, when executed by the processor, cause the processor to:

modify, prior to run time, an executable file of an application to cause an operating system loader to load additional code using a dynamically-linked library, wherein modifying the executable file comprises:

determining that the executable file includes insufficient unused space to accommodate a load command; and

adding the load command to the executable file by: identifying unused space outside of a data portion of the executable file that can be used to accommodate the load command;

wherein the additional code, when executed, causes a change to a pointer in a table that indicates an address of an imported function implementing a system call so that the pointer indicates an address of a customized function.

16. The computing system of claim 15 , wherein the customized function provides network communications through a secure network connection.

17. The computing system of claim 15 , wherein the customized function provides data encryption functionality.

18. The computing system of claim 15 , wherein the storage device further stores instructions that, when executed by the processor, cause the processor to:

receive, at the application, a policy communicated through an inter-process communication mechanism, wherein the customized function provides functionality in accordance with the policy.

19. The computing system of claim 15 , wherein the system call comprises a call to a libc library.

20. The computing system of claim 15 , wherein adding the load command to the executable file further includes, responsive to the executable file including insufficient unused space, moving a portion of the executable file to make space for the load command.