Hi all,
I have changed the sys_call_table[__NR_socketcall] & implemented my own sys_setsockopt(). The code is exactly the same as the original sys_setsockopt().
Now after loading the module, I start getting this message randomly :
socki_lookup: socket file changed!
This comes from sockfd_lookup() if the struct file* from the process file table and sock do not match.
I have included my module code.
Regards, Swapnil.
PS: Sorry for cluttering the devel list but kernelnewbies list seems to be non functional.
#include <linux/module.h> #include <linux/kernel.h> #include <linux/errno.h> #include <asm/uaccess.h> #include <linux/unistd.h> #include <linux/net.h>
asmlinkage long (*save_sys_socketcall)(int call, unsigned long *args) = NULL;
extern void *sys_call_table[];
asmlinkage long my_setsockopt(int fd, int level,
int optname, char *optval, int optlen) {int err; struct socket *sock;
if (optlen < 0)
return -EINVAL; if ((sock = sockfd_lookup(fd, &err))!=NULL) { if (level == SOL_SOCKET)
err=sock_setsockopt(sock,level,optname,optval,optlen);
else
err=sock->ops->setsockopt(sock, level, optname, optval, optlen);
fput(sock->file); /* since sockfd_put() is not exported */
}return err; }
asmlinkage long my_socketcall(int call, unsigned long *args) { int err;
if (call == SYS_SETSOCKOPT) {
unsigned long a[6]; if (copy_from_user(a, args, 5*sizeof(unsigned long))) {
return -EFAULT;
}
return my_setsockopt(a[0], a[1], a[2], (char*)a[3], a[4]);
}return save_sys_socketcall(call, args); }
int init_mod() { save_sys_socketcall = sys_call_table[__NR_socketcall];
sys_call_table[__NR_socketcall] = my_socketcall;return 0; }
void exit_mod() {
sys_call_table[__NR_socketcall] = save_sys_socketcall;
}module_init(init_mod); module_exit(exit_mod);
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