On 14-Oct-2003 Kiran Kumar wrote:
> --- Pedro Bados <pedrobados@eresmas.net> wrote:
>> - "current>uid" is always 1 indepently the process
>> uid (current->euid works!)
>>
>> - "current->user" is always NULL.
>>
>> - "current->files" pointer seems ok but even after
>> having an open socket,
>> (intercepting sys_connect), the
>> "current->files->fd[fd]" remains NULL.
>
> Could you post your full code, that might help find
> the issue.
Sure, here it goes a simple non-working example:
int my_socketcall(int call,unsigned long *args){
#define nargs 3*sizeof(unsigned long)
struct sockaddr saddr;
unsigned long my_arg[nargs];
/* Same wrong results using current directly */
struct task_struct* curr=get_current();
if (call==SYS_CONNECT){
if (copy_from_user(my_arg,args,nargs)) {
printk("Error copying arguments\n");
goto end;
}
if(copy_from_user(&saddr, \
(struct sockaddr*) my_arg[1],\
sizeof(struct sockaddr))) {
printk("Error copying sockaddr\n");
goto end;
}
if((family=(unsigned int)saddr.sa_family)==PF_INET)
printk("<0>uid:%d puser:%p pfile:%p",\
curr->uid,curr->user,curr->files->fd);
}
end:
return old_socketcall(call,args);
}
--EOF
I get : "uid:0 puser:00000000 pfile:0000000x" for any user.
Since x is a small integer value as 1 or 2 instead of a proper pointer,
attempting to read curr->files->fd[my_arg[0]] produces a violation.
Thanks a lot.
Best regards. Pedro.
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