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System Call Interception

System Call Interception - System Call Interception It is...

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System Call Interception It is important also to install new system calls or intercept existing system calls to add extra functionality. The table of system calls in Linux is defined as: extern void *sys_call_table[]; This is an array of pointer to functions that point to the implementation of the system calls. The indexes of the system calls are defined in /usr/include/syscall.h For example, SYS_open is the system call
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System Call Interception In init_module save the original call to open or the system call to intercept asmlinkage int (*original_call) (const char *, int, int); init_module(..) { original_call = sys_call_table[__NR_open]; sys_call_table[__NR_open] = our_sys_open; In your open implementation call the real call at the end. asmlinkage int our_sys_open(const char *filename, int flags, int mode) { // Other stuff return original_call(filename, flags, mode); }
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System Call Interception /* * syscall.c * * System call "stealing" sample.
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