userns: Convert process event connector to handle kuids and kgids

- Only allow asking for events from the initial user and pid namespace,
  where we generate the events in.

- Convert kuids and kgids into the initial user namespace to report
  them via the process event connector.

Cc: David Miller <davem@davemloft.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

2 files changed, 14 insertions, 5 deletions

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 3e92b7d3fcd2..fce2000eec31 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -30,6 +30,7 @@
 #include <linux/gfp.h>
 #include <linux/ptrace.h>
 #include <linux/atomic.h>
+#include <linux/pid_namespace.h>
 
 #include <asm/unaligned.h>
 
@@ -127,11 +128,11 @@ void proc_id_connector(struct task_struct *task, int which_id)
         rcu_read_lock();
         cred = __task_cred(task);
         if (which_id == PROC_EVENT_UID) {
-                ev->event_data.id.r.ruid = cred->uid;
-                ev->event_data.id.e.euid = cred->euid;
+                ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
+                ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
         } else if (which_id == PROC_EVENT_GID) {
-                ev->event_data.id.r.rgid = cred->gid;
-                ev->event_data.id.e.egid = cred->egid;
+                ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
+                ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
         } else {
                 rcu_read_unlock();
                 return;
@@ -303,6 +304,15 @@ static void cn_proc_mcast_ctl(struct cn_msg *msg,
         if (msg->len != sizeof(*mc_op))
                 return;
 
+        /* 
+         * Events are reported with respect to the initial pid
+         * and user namespaces so ignore requestors from
+         * other namespaces.
+         */
+        if ((current_user_ns() != &init_user_ns) ||
+            (task_active_pid_ns(current) != &init_pid_ns))
+                return;
+
         mc_op = (enum proc_cn_mcast_op *)msg->data;
         switch (*mc_op) {
         case PROC_CN_MCAST_LISTEN:
diff --git a/init/Kconfig b/init/Kconfig
index 071dbb4928ef..7d4422c92cca 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -938,7 +938,6 @@ config UIDGID_CONVERTED
         depends on QUOTACTL = n
         depends on BSD_PROCESS_ACCT = n
         depends on DRM = n
-        depends on PROC_EVENTS = n
 
         # Networking
         depends on NET_9P = n