linux/drivers/connector/cn_proc.c
Keqi Wang 8929f95b2b connector/cn_proc: revert "connector: Fix proc_event_num_listeners count not cleared"
This reverts commit c46bfba133 ("connector: Fix proc_event_num_listeners
count not cleared").

It is not accurate to reset proc_event_num_listeners according to
cn_netlink_send_mult() return value -ESRCH.

In the case of stress-ng netlink-proc, -ESRCH will always be returned,
because netlink_broadcast_filtered will return -ESRCH,
which may cause stress-ng netlink-proc performance degradation.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401112259.b23a1567-oliver.sang@intel.com
Fixes: c46bfba133 ("connector: Fix proc_event_num_listeners count not cleared")
Signed-off-by: Keqi Wang <wangkeqi_chris@163.com>
Link: https://lore.kernel.org/r/20240209091659.68723-1-wangkeqi_chris@163.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-02-13 11:15:44 +01:00

485 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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.
*/
#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 <linux/pid_namespace.h>
#include <linux/cn_proc.h>
#include <linux/local_lock.h>
/*
* Size of a cn_msg followed by a proc_event structure. Since the
* sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
* add one 4-byte word to the size here, and then start the actual
* cn_msg structure 4 bytes into the stack buffer. The result is that
* the immediately following proc_event structure is aligned to 8 bytes.
*/
#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
/* See comment above; we test our assumption about sizeof struct cn_msg here. */
static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
{
BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
return (struct cn_msg *)(buffer + 4);
}
static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
/* local_event.count is used as the sequence number of the netlink message */
struct local_event {
local_lock_t lock;
__u32 count;
};
static DEFINE_PER_CPU(struct local_event, local_event) = {
.lock = INIT_LOCAL_LOCK(lock),
};
static int cn_filter(struct sock *dsk, struct sk_buff *skb, void *data)
{
__u32 what, exit_code, *ptr;
enum proc_cn_mcast_op mc_op;
uintptr_t val;
if (!dsk || !dsk->sk_user_data || !data)
return 0;
ptr = (__u32 *)data;
what = *ptr++;
exit_code = *ptr;
val = ((struct proc_input *)(dsk->sk_user_data))->event_type;
mc_op = ((struct proc_input *)(dsk->sk_user_data))->mcast_op;
if (mc_op == PROC_CN_MCAST_IGNORE)
return 1;
if ((__u32)val == PROC_EVENT_ALL)
return 0;
/*
* Drop packet if we have to report only non-zero exit status
* (PROC_EVENT_NONZERO_EXIT) and exit status is 0
*/
if (((__u32)val & PROC_EVENT_NONZERO_EXIT) &&
(what == PROC_EVENT_EXIT)) {
if (exit_code)
return 0;
}
if ((__u32)val & what)
return 0;
return 1;
}
static inline void send_msg(struct cn_msg *msg)
{
__u32 filter_data[2];
local_lock(&local_event.lock);
msg->seq = __this_cpu_inc_return(local_event.count) - 1;
((struct proc_event *)msg->data)->cpu = smp_processor_id();
/*
* local_lock() disables preemption during send to ensure the messages
* are ordered according to their sequence numbers.
*
* If cn_netlink_send() fails, the data is not sent.
*/
filter_data[0] = ((struct proc_event *)msg->data)->what;
if (filter_data[0] == PROC_EVENT_EXIT) {
filter_data[1] =
((struct proc_event *)msg->data)->event_data.exit.exit_code;
} else {
filter_data[1] = 0;
}
cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
cn_filter, (void *)filter_data);
local_unlock(&local_event.lock);
}
void proc_fork_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
struct task_struct *parent;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_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);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_exec_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_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);
msg->flags = 0; /* not used */
send_msg(msg);
}
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] __aligned(8);
const struct cred *cred;
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_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 = 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 = 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;
}
rcu_read_unlock();
ev->timestamp_ns = ktime_get_ns();
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_sid_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_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);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_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);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_comm_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_ns();
ev->what = PROC_EVENT_COMM;
ev->event_data.comm.process_pid = task->pid;
ev->event_data.comm.process_tgid = task->tgid;
get_task_comm(ev->event_data.comm.comm, task);
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_coredump_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
struct task_struct *parent;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_ns();
ev->what = PROC_EVENT_COREDUMP;
ev->event_data.coredump.process_pid = task->pid;
ev->event_data.coredump.process_tgid = task->tgid;
rcu_read_lock();
if (pid_alive(task)) {
parent = rcu_dereference(task->real_parent);
ev->event_data.coredump.parent_pid = parent->pid;
ev->event_data.coredump.parent_tgid = parent->tgid;
}
rcu_read_unlock();
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
msg->flags = 0; /* not used */
send_msg(msg);
}
void proc_exit_connector(struct task_struct *task)
{
struct cn_msg *msg;
struct proc_event *ev;
struct task_struct *parent;
__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
ev->timestamp_ns = ktime_get_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;
rcu_read_lock();
if (pid_alive(task)) {
parent = rcu_dereference(task->real_parent);
ev->event_data.exit.parent_pid = parent->pid;
ev->event_data.exit.parent_tgid = parent->tgid;
}
rcu_read_unlock();
memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
msg->ack = 0; /* not used */
msg->len = sizeof(*ev);
msg->flags = 0; /* not used */
send_msg(msg);
}
/*
* 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] __aligned(8);
if (atomic_read(&proc_event_num_listeners) < 1)
return;
msg = buffer_to_cn_msg(buffer);
ev = (struct proc_event *)msg->data;
memset(&ev->event_data, 0, sizeof(ev->event_data));
msg->seq = rcvd_seq;
ev->timestamp_ns = ktime_get_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);
msg->flags = 0; /* not used */
send_msg(msg);
}
/**
* cn_proc_mcast_ctl
* @msg: message sent from userspace via the connector
* @nsp: NETLINK_CB of the client's socket buffer
*/
static void cn_proc_mcast_ctl(struct cn_msg *msg,
struct netlink_skb_parms *nsp)
{
enum proc_cn_mcast_op mc_op = 0, prev_mc_op = 0;
struct proc_input *pinput = NULL;
enum proc_cn_event ev_type = 0;
int err = 0, initial = 0;
struct sock *sk = NULL;
/*
* 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_is_in_init_pid_ns(current))
return;
if (msg->len == sizeof(*pinput)) {
pinput = (struct proc_input *)msg->data;
mc_op = pinput->mcast_op;
ev_type = pinput->event_type;
} else if (msg->len == sizeof(mc_op)) {
mc_op = *((enum proc_cn_mcast_op *)msg->data);
ev_type = PROC_EVENT_ALL;
} else {
return;
}
ev_type = valid_event((enum proc_cn_event)ev_type);
if (ev_type == PROC_EVENT_NONE)
ev_type = PROC_EVENT_ALL;
if (nsp->sk) {
sk = nsp->sk;
if (sk->sk_user_data == NULL) {
sk->sk_user_data = kzalloc(sizeof(struct proc_input),
GFP_KERNEL);
if (sk->sk_user_data == NULL) {
err = ENOMEM;
goto out;
}
initial = 1;
} else {
prev_mc_op =
((struct proc_input *)(sk->sk_user_data))->mcast_op;
}
((struct proc_input *)(sk->sk_user_data))->event_type =
ev_type;
((struct proc_input *)(sk->sk_user_data))->mcast_op = mc_op;
}
switch (mc_op) {
case PROC_CN_MCAST_LISTEN:
if (initial || (prev_mc_op != PROC_CN_MCAST_LISTEN))
atomic_inc(&proc_event_num_listeners);
break;
case PROC_CN_MCAST_IGNORE:
if (!initial && (prev_mc_op != PROC_CN_MCAST_IGNORE))
atomic_dec(&proc_event_num_listeners);
((struct proc_input *)(sk->sk_user_data))->event_type =
PROC_EVENT_NONE;
break;
default:
err = EINVAL;
break;
}
out:
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 = cn_add_callback(&cn_proc_event_id,
"cn_proc",
&cn_proc_mcast_ctl);
if (err) {
pr_warn("cn_proc failed to register\n");
return err;
}
return 0;
}
device_initcall(cn_proc_init);