[RFC][PATCH 7/7][v4] SI_TKILL: Masquerade si_pid when crossing pid ns boundary

Sukadev Bhattiprolu
2008-12-24T11:55:24Z

From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Subject: [RFC][PATCH 7/7][v4] SI_TKILL: Masquerade si_pid when crossing pid ns boundary

When sending a signal to a process in a descendant namespace, ->si_pid
must be set to the pid of sender in receiver's namespace. But if the
receiver is exiting (theoretically, ns == NULL), just set ->si_pid to
active pid namespace of sender (receiver won't see the signal anyway ?).

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
kernel/signal.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 5a6aea8..e263c23 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2385,17 +2385,22 @@ static int do_tkill(pid_t tgid, pid_t pid, int sig)
struct siginfo info;
struct task_struct *p;
unsigned long flags;
+ struct pid_namespace *ns;

error = -ESRCH;
info.si_signo = sig;
info.si_errno = 0;
info.si_code = SI_TKILL;
- info.si_pid = task_tgid_vnr(current);
info.si_uid = current_uid();

rcu_read_lock();
p = find_task_by_vpid(pid);
if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
+ ns = task_active_pid_ns(p);
+ if (ns)
+ info.si_pid = task_tgid_nr_ns(current, ns);
+ else
+ info.si_pid = task_tgid_vnr(current);
error = check_kill_permission(sig, &info, p);
/*
* The null signal is a permissions and process existence
--
1.5.2.5