Quelle taskstats.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* taskstats.c - Export per-task statistics to userland
*
* Copyright (C) Shailabh Nagar, IBM Corp. 2006
*           (C) Balbir Singh,   IBM Corp. 2006
*/

#include <linux/kernel.h>
#include <linux/taskstats_kern.h>
#include <linux/tsacct_kern.h>
#include <linux/acct.h>
#include <linux/delayacct.h>
#include <linux/cpumask.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <linux/cgroupstats.h>
#include <linux/cgroup.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/pid_namespace.h>
#include <net/genetlink.h>
#include <linux/atomic.h>
#include <linux/sched/cputime.h>

/*
* Maximum length of a cpumask that can be specified in
* the TASKSTATS_CMD_ATTR_REGISTER/DEREGISTER_CPUMASK attribute
*/
#define TASKSTATS_CPUMASK_MAXLEN (100+6*NR_CPUS)

static DEFINE_PER_CPU(__u32, taskstats_seqnum);
static int family_registered;
struct kmem_cache *taskstats_cache;

static struct genl_family family;

static const struct nla_policy taskstats_cmd_get_policy[] = {
[TASKSTATS_CMD_ATTR_PID]  = { .type = NLA_U32 },
[TASKSTATS_CMD_ATTR_TGID] = { .type = NLA_U32 },
[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK] = { .type = NLA_STRING },
[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK] = { .type = NLA_STRING },};

static const struct nla_policy cgroupstats_cmd_get_policy[] = {
[CGROUPSTATS_CMD_ATTR_FD] = { .type = NLA_U32 },
};

struct listener {
struct list_head list;
pid_t pid;
char valid;
};

struct listener_list {
struct rw_semaphore sem;
struct list_head list;
};
static DEFINE_PER_CPU(struct listener_list, listener_array);

enum actions {
REGISTER,
DEREGISTER,
CPU_DONT_CARE
};

static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp,
    size_t size)
{
struct sk_buff *skb;
void *reply;

/*
* If new attributes are added, please revisit this allocation
*/
skb = genlmsg_new(size, GFP_KERNEL);
if (!skb)
  return -ENOMEM;

if (!info) {
  int seq = this_cpu_inc_return(taskstats_seqnum) - 1;

  reply = genlmsg_put(skb, 0, seq, &family, 0, cmd);
} else
  reply = genlmsg_put_reply(skb, info, &family, 0, cmd);
if (reply == NULL) {
  nlmsg_free(skb);
  return -EINVAL;
}

*skbp = skb;
return 0;
}

/*
* Send taskstats data in @skb to listener with nl_pid @pid
*/
static int send_reply(struct sk_buff *skb, struct genl_info *info)
{
struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
void *reply = genlmsg_data(genlhdr);

genlmsg_end(skb, reply);

return genlmsg_reply(skb, info);
}

/*
* Send taskstats data in @skb to listeners registered for @cpu's exit data
*/
static void send_cpu_listeners(struct sk_buff *skb,
     struct listener_list *listeners)
{
struct genlmsghdr *genlhdr = nlmsg_data(nlmsg_hdr(skb));
struct listener *s, *tmp;
struct sk_buff *skb_next, *skb_cur = skb;
void *reply = genlmsg_data(genlhdr);
int delcount = 0;

genlmsg_end(skb, reply);

down_read(&listeners->sem);
list_for_each_entry(s, &listeners->list, list) {
  int rc;

  skb_next = NULL;
  if (!list_is_last(&s->list, &listeners->list)) {
   skb_next = skb_clone(skb_cur, GFP_KERNEL);
   if (!skb_next)
    break;
  }
  rc = genlmsg_unicast(&init_net, skb_cur, s->pid);
  if (rc == -ECONNREFUSED) {
   s->valid = 0;
   delcount++;
  }
  skb_cur = skb_next;
}
up_read(&listeners->sem);

if (skb_cur)
  nlmsg_free(skb_cur);

if (!delcount)
  return;

/* Delete invalidated entries */
down_write(&listeners->sem);
list_for_each_entry_safe(s, tmp, &listeners->list, list) {
  if (!s->valid) {
   list_del(&s->list);
   kfree(s);
  }
}
up_write(&listeners->sem);
}

static void exe_add_tsk(struct taskstats *stats, struct task_struct *tsk)
{
/* No idea if I'm allowed to access that here, now. */
struct file *exe_file = get_task_exe_file(tsk);

if (exe_file) {
  /* Following cp_new_stat64() in stat.c . */
  stats->ac_exe_dev =
   huge_encode_dev(exe_file->f_inode->i_sb->s_dev);
  stats->ac_exe_inode = exe_file->f_inode->i_ino;
  fput(exe_file);
} else {
  stats->ac_exe_dev = 0;
  stats->ac_exe_inode = 0;
}
}

static void fill_stats(struct user_namespace *user_ns,
         struct pid_namespace *pid_ns,
         struct task_struct *tsk, struct taskstats *stats)
{
memset(stats, 0, sizeof(*stats));
/*
* Each accounting subsystem adds calls to its functions to
* fill in relevant parts of struct taskstsats as follows
*
* per-task-foo(stats, tsk);
*/

delayacct_add_tsk(stats, tsk);

/* fill in basic acct fields */
stats->version = TASKSTATS_VERSION;
stats->nvcsw = tsk->nvcsw;
stats->nivcsw = tsk->nivcsw;
bacct_add_tsk(user_ns, pid_ns, stats, tsk);

/* fill in extended acct fields */
xacct_add_tsk(stats, tsk);

/* add executable info */
exe_add_tsk(stats, tsk);
}

static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
{
struct task_struct *tsk;

tsk = find_get_task_by_vpid(pid);
if (!tsk)
  return -ESRCH;
fill_stats(current_user_ns(), task_active_pid_ns(current), tsk, stats);
put_task_struct(tsk);
return 0;
}

static int fill_stats_for_tgid(pid_t tgid, struct taskstats *stats)
{
struct task_struct *tsk, *first;
unsigned long flags;
int rc = -ESRCH;
u64 delta, utime, stime;
u64 start_time;

/*
* Add additional stats from live tasks except zombie thread group
* leaders who are already counted with the dead tasks
*/
rcu_read_lock();
first = find_task_by_vpid(tgid);

if (!first || !lock_task_sighand(first, &flags))
  goto out;

if (first->signal->stats)
  memcpy(stats, first->signal->stats, sizeof(*stats));
else
  memset(stats, 0, sizeof(*stats));

start_time = ktime_get_ns();
for_each_thread(first, tsk) {
  if (tsk->exit_state)
   continue;
  /*
* Accounting subsystem can call its functions here to
* fill in relevant parts of struct taskstsats as follows
*
* per-task-foo(stats, tsk);
*/
  delayacct_add_tsk(stats, tsk);

  /* calculate task elapsed time in nsec */
  delta = start_time - tsk->start_time;
  /* Convert to micro seconds */
  do_div(delta, NSEC_PER_USEC);
  stats->ac_etime += delta;

  task_cputime(tsk, &utime, &stime);
  stats->ac_utime += div_u64(utime, NSEC_PER_USEC);
  stats->ac_stime += div_u64(stime, NSEC_PER_USEC);

  stats->nvcsw += tsk->nvcsw;
  stats->nivcsw += tsk->nivcsw;
}

unlock_task_sighand(first, &flags);
rc = 0;
out:
rcu_read_unlock();

stats->version = TASKSTATS_VERSION;
/*
* Accounting subsystems can also add calls here to modify
* fields of taskstats.
*/
return rc;
}

static void fill_tgid_exit(struct task_struct *tsk)
{
unsigned long flags;

spin_lock_irqsave(&tsk->sighand->siglock, flags);
if (!tsk->signal->stats)
  goto ret;

/*
* Each accounting subsystem calls its functions here to
* accumalate its per-task stats for tsk, into the per-tgid structure
*
* per-task-foo(tsk->signal->stats, tsk);
*/
delayacct_add_tsk(tsk->signal->stats, tsk);
ret:
spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
return;
}

static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
{
struct listener_list *listeners;
struct listener *s, *tmp, *s2;
unsigned int cpu;
int ret = 0;

if (!cpumask_subset(mask, cpu_possible_mask))
  return -EINVAL;

if (current_user_ns() != &init_user_ns)
  return -EINVAL;

if (task_active_pid_ns(current) != &init_pid_ns)
  return -EINVAL;

if (isadd == REGISTER) {
  for_each_cpu(cpu, mask) {
   s = kmalloc_node(sizeof(struct listener),
     GFP_KERNEL, cpu_to_node(cpu));
   if (!s) {
    ret = -ENOMEM;
    goto cleanup;
   }
   s->pid = pid;
   s->valid = 1;

   listeners = &per_cpu(listener_array, cpu);
   down_write(&listeners->sem);
   list_for_each_entry(s2, &listeners->list, list) {
    if (s2->pid == pid && s2->valid)
     goto exists;
   }
   list_add(&s->list, &listeners->list);
   s = NULL;
exists:
   up_write(&listeners->sem);
   kfree(s); /* nop if NULL */
  }
  return 0;
}

/* Deregister or cleanup */
cleanup:
for_each_cpu(cpu, mask) {
  listeners = &per_cpu(listener_array, cpu);
  down_write(&listeners->sem);
  list_for_each_entry_safe(s, tmp, &listeners->list, list) {
   if (s->pid == pid) {
    list_del(&s->list);
    kfree(s);
    break;
   }
  }
  up_write(&listeners->sem);
}
return ret;
}

static int parse(struct nlattr *na, struct cpumask *mask)
{
char *data;
int len;
int ret;

if (na == NULL)
  return 1;
len = nla_len(na);
if (len > TASKSTATS_CPUMASK_MAXLEN)
  return -E2BIG;
if (len < 1)
  return -EINVAL;
data = kmalloc(len, GFP_KERNEL);
if (!data)
  return -ENOMEM;
nla_strscpy(data, na, len);
ret = cpulist_parse(data, mask);
kfree(data);
return ret;
}

static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
{
struct nlattr *na, *ret;
int aggr;

aggr = (type == TASKSTATS_TYPE_PID)
   ? TASKSTATS_TYPE_AGGR_PID
   : TASKSTATS_TYPE_AGGR_TGID;

na = nla_nest_start_noflag(skb, aggr);
if (!na)
  goto err;

if (nla_put(skb, type, sizeof(pid), &pid) < 0) {
  nla_nest_cancel(skb, na);
  goto err;
}
ret = nla_reserve_64bit(skb, TASKSTATS_TYPE_STATS,
    sizeof(struct taskstats), TASKSTATS_TYPE_NULL);
if (!ret) {
  nla_nest_cancel(skb, na);
  goto err;
}
nla_nest_end(skb, na);

return nla_data(ret);
err:
return NULL;
}

static int cgroupstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
{
int rc = 0;
struct sk_buff *rep_skb;
struct cgroupstats *stats;
struct nlattr *na;
size_t size;
u32 fd;

na = info->attrs[CGROUPSTATS_CMD_ATTR_FD];
if (!na)
  return -EINVAL;

fd = nla_get_u32(info->attrs[CGROUPSTATS_CMD_ATTR_FD]);
CLASS(fd, f)(fd);
if (fd_empty(f))
  return 0;

size = nla_total_size(sizeof(struct cgroupstats));

rc = prepare_reply(info, CGROUPSTATS_CMD_NEW, &rep_skb,
    size);
if (rc < 0)
  return rc;

na = nla_reserve(rep_skb, CGROUPSTATS_TYPE_CGROUP_STATS,
    sizeof(struct cgroupstats));
if (na == NULL) {
  nlmsg_free(rep_skb);
  return -EMSGSIZE;
}

stats = nla_data(na);
memset(stats, 0, sizeof(*stats));

rc = cgroupstats_build(stats, fd_file(f)->f_path.dentry);
if (rc < 0) {
  nlmsg_free(rep_skb);
  return rc;
}

return send_reply(rep_skb, info);
}

static int cmd_attr_register_cpumask(struct genl_info *info)
{
cpumask_var_t mask;
int rc;

if (!alloc_cpumask_var(&mask, GFP_KERNEL))
  return -ENOMEM;
rc = parse(info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK], mask);
if (rc < 0)
  goto out;
rc = add_del_listener(info->snd_portid, mask, REGISTER);
out:
free_cpumask_var(mask);
return rc;
}

static int cmd_attr_deregister_cpumask(struct genl_info *info)
{
cpumask_var_t mask;
int rc;

if (!alloc_cpumask_var(&mask, GFP_KERNEL))
  return -ENOMEM;
rc = parse(info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK], mask);
if (rc < 0)
  goto out;
rc = add_del_listener(info->snd_portid, mask, DEREGISTER);
out:
free_cpumask_var(mask);
return rc;
}

static size_t taskstats_packet_size(void)
{
size_t size;

size = nla_total_size(sizeof(u32)) +
  nla_total_size_64bit(sizeof(struct taskstats)) +
  nla_total_size(0);

return size;
}

static int cmd_attr_pid(struct genl_info *info)
{
struct taskstats *stats;
struct sk_buff *rep_skb;
size_t size;
u32 pid;
int rc;

size = taskstats_packet_size();

rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
if (rc < 0)
  return rc;

rc = -EINVAL;
pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
if (!stats)
  goto err;

rc = fill_stats_for_pid(pid, stats);
if (rc < 0)
  goto err;
return send_reply(rep_skb, info);
err:
nlmsg_free(rep_skb);
return rc;
}

static int cmd_attr_tgid(struct genl_info *info)
{
struct taskstats *stats;
struct sk_buff *rep_skb;
size_t size;
u32 tgid;
int rc;

size = taskstats_packet_size();

rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, size);
if (rc < 0)
  return rc;

rc = -EINVAL;
tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
if (!stats)
  goto err;

rc = fill_stats_for_tgid(tgid, stats);
if (rc < 0)
  goto err;
return send_reply(rep_skb, info);
err:
nlmsg_free(rep_skb);
return rc;
}

static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
{
if (info->attrs[TASKSTATS_CMD_ATTR_REGISTER_CPUMASK])
  return cmd_attr_register_cpumask(info);
else if (info->attrs[TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK])
  return cmd_attr_deregister_cpumask(info);
else if (info->attrs[TASKSTATS_CMD_ATTR_PID])
  return cmd_attr_pid(info);
else if (info->attrs[TASKSTATS_CMD_ATTR_TGID])
  return cmd_attr_tgid(info);
else
  return -EINVAL;
}

static struct taskstats *taskstats_tgid_alloc(struct task_struct *tsk)
{
struct signal_struct *sig = tsk->signal;
struct taskstats *stats_new, *stats;

/* Pairs with smp_store_release() below. */
stats = smp_load_acquire(&sig->stats);
if (stats || thread_group_empty(tsk))
  return stats;

/* No problem if kmem_cache_zalloc() fails */
stats_new = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);

spin_lock_irq(&tsk->sighand->siglock);
stats = sig->stats;
if (!stats) {
  /*
* Pairs with smp_store_release() above and order the
* kmem_cache_zalloc().
*/
  smp_store_release(&sig->stats, stats_new);
  stats = stats_new;
  stats_new = NULL;
}
spin_unlock_irq(&tsk->sighand->siglock);

if (stats_new)
  kmem_cache_free(taskstats_cache, stats_new);

return stats;
}

/* Send pid data out on exit */
void taskstats_exit(struct task_struct *tsk, int group_dead)
{
int rc;
struct listener_list *listeners;
struct taskstats *stats;
struct sk_buff *rep_skb;
size_t size;
int is_thread_group;

if (!family_registered)
  return;

/*
* Size includes space for nested attributes
*/
size = taskstats_packet_size();

is_thread_group = !!taskstats_tgid_alloc(tsk);
if (is_thread_group) {
  /* PID + STATS + TGID + STATS */
  size = 2 * size;
  /* fill the tsk->signal->stats structure */
  fill_tgid_exit(tsk);
}

listeners = raw_cpu_ptr(&listener_array);
if (list_empty(&listeners->list))
  return;

rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, size);
if (rc < 0)
  return;

stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID,
    task_pid_nr_ns(tsk, &init_pid_ns));
if (!stats)
  goto err;

fill_stats(&init_user_ns, &init_pid_ns, tsk, stats);
if (group_dead)
  stats->ac_flag |= AGROUP;

/*
* Doesn't matter if tsk is the leader or the last group member leaving
*/
if (!is_thread_group || !group_dead)
  goto send;

stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID,
    task_tgid_nr_ns(tsk, &init_pid_ns));
if (!stats)
  goto err;

memcpy(stats, tsk->signal->stats, sizeof(*stats));

send:
send_cpu_listeners(rep_skb, listeners);
return;
err:
nlmsg_free(rep_skb);
}

static const struct genl_ops taskstats_ops[] = {
{
  .cmd  = TASKSTATS_CMD_GET,
  .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
  .doit  = taskstats_user_cmd,
  .policy  = taskstats_cmd_get_policy,
  .maxattr = ARRAY_SIZE(taskstats_cmd_get_policy) - 1,
  .flags  = GENL_ADMIN_PERM,
},
{
  .cmd  = CGROUPSTATS_CMD_GET,
  .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
  .doit  = cgroupstats_user_cmd,
  .policy  = cgroupstats_cmd_get_policy,
  .maxattr = ARRAY_SIZE(cgroupstats_cmd_get_policy) - 1,
},
};

static struct genl_family family __ro_after_init = {
.name  = TASKSTATS_GENL_NAME,
.version = TASKSTATS_GENL_VERSION,
.module  = THIS_MODULE,
.ops  = taskstats_ops,
.n_ops  = ARRAY_SIZE(taskstats_ops),
.resv_start_op = CGROUPSTATS_CMD_GET + 1,
.netnsok = true,
};

/* Needed early in initialization */
void __init taskstats_init_early(void)
{
unsigned int i;

taskstats_cache = KMEM_CACHE(taskstats, SLAB_PANIC);
for_each_possible_cpu(i) {
  INIT_LIST_HEAD(&(per_cpu(listener_array, i).list));
  init_rwsem(&(per_cpu(listener_array, i).sem));
}
}

static int __init taskstats_init(void)
{
int rc;

rc = genl_register_family(&family);
if (rc)
  return rc;

family_registered = 1;
pr_info("registered taskstats version %d\n", TASKSTATS_GENL_VERSION);
return 0;
}

/*
* late initcall ensures initialization of statistics collection
* mechanisms precedes initialization of the taskstats interface
*/
late_initcall(taskstats_init);

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