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linux/drivers/connector/cn_proc.c
Oleg Nesterov 9e8f90dfe5 proc_fork_connector: a lockless ->real_parent usage is not safe 
proc_fork_connector() uses ->real_parent lockless.  This is not safe if
copy_process() was called with CLONE_THREAD or CLONE_PARENT, in this case
the parent != current can go away at any moment.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-07-28 18:26:32 -07:00

313 lines
8.7 KiB
C
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/*
* cn_proc.c - process events connector
*
* Copyright (C) Matt Helsley, IBM Corp. 2005
* Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
* Original copyright notice follows:
* Copyright (C) 2005 BULL SA.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/init.h>
#include <linux/connector.h>
#include <linux/gfp.h>
#include <linux/ptrace.h>
#include <linux/atomic.h>
#include <asm/unaligned.h>
#include <linux/cn_proc.h>
#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event))
static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
/* proc_event_counts is used as the sequence number of the netlink message */
static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
static inline void get_seq(__u32 *ts, int *cpu)
{
preempt_disable();
*ts = __this_cpu_inc_return(proc_event_counts) -1;
*cpu = smp_processor_id();
preempt_enable();
}
void proc_fork_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE];
struct timespec ts;
struct task_struct *parent;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg*)buffer;
ev = (struct proc_event*)msg->data;
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->what = PROC_EVENT_FORK;
rcu_read_lock();
parent = rcu_dereference(task->real_parent);
ev->event_data.fork.parent_pid = parent->pid;
ev->event_data.fork.parent_tgid = parent->tgid;
rcu_read_unlock();
ev->event_data.fork.child_pid = task->pid;
ev->event_data.fork.child_tgid = task->tgid;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
/* If cn_netlink_send() failed, the data is not sent */
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
void proc_exec_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
struct timespec ts;
__u8 buffer[CN_PROC_MSG_SIZE];
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg*)buffer;
ev = (struct proc_event*)msg->data;
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->what = PROC_EVENT_EXEC;
ev->event_data.exec.process_pid = task->pid;
ev->event_data.exec.process_tgid = task->tgid;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
void proc_id_connector(struct task_struct *task, int which_id)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE];
struct timespec ts;
const struct cred *cred;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg*)buffer;
ev = (struct proc_event*)msg->data;
ev->what = which_id;
ev->event_data.id.process_pid = task->pid;
ev->event_data.id.process_tgid = task->tgid;
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;
} else if (which_id == PROC_EVENT_GID) {
ev->event_data.id.r.rgid = cred->gid;
ev->event_data.id.e.egid = cred->egid;
} else {
rcu_read_unlock();
return;
}
rcu_read_unlock();
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
void proc_sid_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
struct timespec ts;
__u8 buffer[CN_PROC_MSG_SIZE];
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg *)buffer;
ev = (struct proc_event *)msg->data;
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->what = PROC_EVENT_SID;
ev->event_data.sid.process_pid = task->pid;
ev->event_data.sid.process_tgid = task->tgid;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
{
struct cn_msg *msg;
struct proc_event *ev;
struct timespec ts;
__u8 buffer[CN_PROC_MSG_SIZE];
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg *)buffer;
ev = (struct proc_event *)msg->data;
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->what = PROC_EVENT_PTRACE;
ev->event_data.ptrace.process_pid = task->pid;
ev->event_data.ptrace.process_tgid = task->tgid;
if (ptrace_id == PTRACE_ATTACH) {
ev->event_data.ptrace.tracer_pid = current->pid;
ev->event_data.ptrace.tracer_tgid = current->tgid;
} else if (ptrace_id == PTRACE_DETACH) {
ev->event_data.ptrace.tracer_pid = 0;
ev->event_data.ptrace.tracer_tgid = 0;
} else
return;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
void proc_exit_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE];
struct timespec ts;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg*)buffer;
ev = (struct proc_event*)msg->data;
get_seq(&msg->seq, &ev->cpu);
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->what = PROC_EVENT_EXIT;
ev->event_data.exit.process_pid = task->pid;
ev->event_data.exit.process_tgid = task->tgid;
ev->event_data.exit.exit_code = task->exit_code;
ev->event_data.exit.exit_signal = task->exit_signal;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
/*
* Send an acknowledgement message to userspace
*
* Use 0 for success, EFOO otherwise.
* Note: this is the negative of conventional kernel error
* values because it's not being returned via syscall return
* mechanisms.
*/
static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE];
struct timespec ts;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = (struct cn_msg*)buffer;
ev = (struct proc_event*)msg->data;
msg->seq = rcvd_seq;
ktime_get_ts(&ts); /* get high res monotonic timestamp */
put_unaligned(timespec_to_ns(&ts), (__u64 *)&ev->timestamp_ns);
ev->cpu = -1;
ev->what = PROC_EVENT_NONE;
ev->event_data.ack.err = err;
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = rcvd_ack + 1;
msg->len = sizeof(*ev);
cn_netlink_send(msg, CN_IDX_PROC, GFP_KERNEL);
}
/**
* cn_proc_mcast_ctl
* @data: message sent from userspace via the connector
*/
static void cn_proc_mcast_ctl(struct cn_msg *msg,
struct netlink_skb_parms *nsp)
{
enum proc_cn_mcast_op *mc_op = NULL;
int err = 0;
if (msg->len != sizeof(*mc_op))
return;
mc_op = (enum proc_cn_mcast_op*)msg->data;
switch (*mc_op) {
case PROC_CN_MCAST_LISTEN:
atomic_inc(&proc_event_num_listeners);
break;
case PROC_CN_MCAST_IGNORE:
atomic_dec(&proc_event_num_listeners);
break;
default:
err = EINVAL;
break;
}
cn_proc_ack(err, msg->seq, msg->ack);
}
/*
* cn_proc_init - initialization entry point
*
* Adds the connector callback to the connector driver.
*/
static int __init cn_proc_init(void)
{
int err;
if ((err = cn_add_callback(&cn_proc_event_id, "cn_proc",
&cn_proc_mcast_ctl))) {
printk(KERN_WARNING "cn_proc failed to register\n");
return err;
}
return 0;
}
module_init(cn_proc_init);
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