Re: [PATCH] sys_capget should use current if the pid argument is 0

[Chris Wright <chris@wirex.com>]

* Daniel Jacobowitz (dan@debian.org) wrote:
> On Fri, Oct 11, 2002 at 07:58:46PM -0700, Linus Torvalds wrote:
> > 
> > On Thu, 10 Oct 2002, Chris Wright wrote:
> > > 
> > > The patch below fixes my oversight.  The locking is left the way it was,
> > > and just the pid 0 part is fixed as well as the duplicate code removed.
> > 
> > All right, call me stupid, but twhere is the "duplication" in the code you 
> > removed?
> > 
> > I see the "security/capability.c" thing, yes, but I also look at
> > "security/dummy.c", and it appears that at least for that case nobody
> > would ever initialize the capabilities that we return to user space at
> > all.
> > 
> > So there's a bug somewhere there, and removing the duplication makes 
> > things worse (admittedly for a case which isn't enabled in the regular 
> > kernel, but still..)
> > 
> > So I'd ask you to have patience with me, and send a third patch that gets 
> > this thing right too.. 
> 
> Since this is still broken a month later... I don't know what to do
> about the "duplication" question, but I'll leave that to Chris.  This
> is the uncontroversial portion of Chris's patch; its affect is to
> change my zsh shell prompt back to a '%' as I'd expect.

Thanks Daniel.  I've been using the patch below, which differs only
slightly from the one you posted (code style matches the same lookup in
sys_capset).  I'll follow up with the patch that removes the duplicate
code.

[PATCH] sys_capget should use current if the pid argument is 0

===== kernel/capability.c 1.5 vs edited =====
--- 1.5/kernel/capability.c	Sun Sep 15 12:19:29 2002
+++ edited/kernel/capability.c	Tue Nov 19 15:57:15 2002
@@ -54,11 +54,14 @@
      spin_lock(&task_capability_lock);
      read_lock(&tasklist_lock); 
 
-     target = find_task_by_pid(pid);
-     if (!target) {
-          ret = -ESRCH;
-          goto out;
-     }
+     if (pid && pid != current->pid) {
+	     target = find_task_by_pid(pid);
+	     if (!target) {
+	          ret = -ESRCH;
+	          goto out;
+	     }
+     } else
+	     target = current;
 
      data.permitted = cap_t(target->cap_permitted);
      data.inheritable = cap_t(target->cap_inheritable);