On Wed, 2007-10-31 at 18:49 -0500, Serge E. Hallyn wrote: > >From 5bff8967f45a35f858b96ca673d9bf98eac53d49 Mon Sep 17 00:00:00 2001 > From: Serge E. Hallyn <[EMAIL PROTECTED]> > Date: Wed, 31 Oct 2007 11:22:04 -0500 > Subject: [PATCH 1/1] file capabilities: allow sigcont within session (v2) > > (This is a proposed fix to http://bugzilla.kernel.org/show_bug.cgi?id=9247) > > Allow sigcont to be sent to a process with greater capabilities > if it is in the same session. Otherwise, a shell from which > I've started a root shell and done 'suspend' can't be restarted > by the parent shell. > > Also don't do file-capabilities signaling checks when uids for > the processes don't match, since the standard check_kill_permission > will have done those checks.
Description doesn't match the code. And in the non-matching uid case, check_kill_permission typically returns an error before it reaches cap_task_kill (modulo the special cases). > > Signed-off-by: Serge E. Hallyn <[EMAIL PROTECTED]> > --- > security/commoncap.c | 9 +++++++++ > 1 files changed, 9 insertions(+), 0 deletions(-) > > diff --git a/security/commoncap.c b/security/commoncap.c > index bf67871..4de6857 100644 > --- a/security/commoncap.c > +++ b/security/commoncap.c > @@ -526,6 +526,15 @@ int cap_task_kill(struct task_struct *p, struct siginfo > *info, > if (info != SEND_SIG_NOINFO && (is_si_special(info) || > SI_FROMKERNEL(info))) > return 0; > > + /* if tasks have same uid, then check_kill_permission did check */ > + if (current->uid == p->uid || current->euid == p->uid || > + current->uid == p->suid || current->euid == p->suid) > + return 0; I'm confused - if you are allowing all signals within the same uid, then what was the point of having a cap_task_kill at all? cap_task_kill was supposed to prevent a process with lesser capabilities from killing a process with more capabilities, even if they have the same uid, so that when you have a program marked with file capabilities instead of a setuid-0 program, that program can't be sent arbitrary signals by the caller. > + > + /* sigcont is permitted within same session */ > + if (sig == SIGCONT && (task_session_nr(current)==task_session_nr(p))) > + return 0; > + > if (secid) > /* > * Signal sent as a particular user. -- Stephen Smalley National Security Agency - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
