Messages in this thread | | | Date | Wed, 28 Apr 2010 10:10:15 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 3/3] RFC: p9auth: add p9auth fs |
| |
Quoting Oleg Nesterov (oleg@redhat.com): > On 04/27, Serge E. Hallyn wrote: > > > > This introduces a Plan 9 style setuid capability filesystem. > > See Documentation/p9auth.txt for a description of how to use this. > > Can't comment these changes due to the lack of knowledge, just > a couple of minor nits.
Thanks, Oleg.
> > +static ssize_t p9auth_use_write(struct file *file, const char __user *buffer, > > + size_t count, loff_t *ppos) > > +{ > > + ssize_t retval = -ENOMEM; > > + char *user_buf; > > + > > + if (mutex_lock_interruptible(&cap_mutex)) > > + return -EINTR; > > EINTR doesn't look exactly right here, especially if TIF_SIGPENDING is > spurious. Probably ERESTARTNOINTR makes more sense. Or mutex_lock_killable().
Ashwin had had this as ERESTARTSYS I believe. I'd read something about userspace should only see -EINTR so I changed it. Sounds like I need to follow the caller chain some more and learn a thing or two, before I repost.
> > + user_buf = kzalloc(count+1, GFP_KERNEL); > > Probably this is OK, but it looks a bit strange we do no check that > count is not too large.
Yes, I should check that, thanks!
> > + if (copy_from_user(user_buf, buffer, count)) { > > + retval = -EFAULT; > > + goto out; > > + } > > + > > + retval = use_setuid_capability(user_buf); > > It seems that use_setuid_capability() pathes assume that user_buf is > null terminated? Say, parse_user_capability() does kstrdup(user_buf).
I kzalloc()d to count+1 before, and only copy_from_user() count bytes, so the last byte should always be 0.
Thanks again,
-serge
| |