Re: [RFC v2 00/10] snet: Security for NETwork syscalls

Tetsuo Handa [off-list ref] writes:

Regarding [RFC v2 09/10] snet: introduce snet_ticket
+enum snet_verdict snet_ticket_check(struct snet_info *info)
+{
+       struct snet_ticket *st = NULL;
+       unsigned int h = 0, verdict = SNET_VERDICT_NONE;
+       struct list_head *l = NULL;
+       struct snet_task_security *tsec = NULL;
+
+       if (snet_ticket_mode == SNET_TICKET_OFF)
+               goto out;
+
+       tsec = (struct snet_task_security*) current_security();
+
+       h = jhash_2words(info->syscall, info->protocol, 0) % HSIZE;
+       l = &tsec->hash[h];
+
+       read_lock_bh(&tsec->lock);

Credentials are allocated for copy-on-write basis.
Sharing "tsec" among multiple "struct task_struct" is what you intended?

No, there is no shared "tsec".
snet_ticket_check() is called from the process context. So "tsec" is
a pointer to the "void *security" pointer from its own "struct
task_struct".

every task_struct have a "tsec" allocated to its "void *security"
pointer. 

I will take a second look on how to access the credentials COW.

Regards.

Tetsuo, thank you again for reviewing.
sam