drivers/misc/uid_cputime.c

   1 /* drivers/misc/uid_cputime.c
   2  *
   3  * Copyright (C) 2014 - 2015 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/atomic.h>
  17 #include <linux/err.h>
  18 #include <linux/hashtable.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/list.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/profile.h>
  24 #include <linux/sched.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/slab.h>
  27 #include <linux/uaccess.h>
  28
  29 #define UID_HASH_BITS   10
  30 DECLARE_HASHTABLE(hash_table, UID_HASH_BITS);
  31
  32 static DEFINE_MUTEX(uid_lock);
  33 static struct proc_dir_entry *parent;
  34
  35 struct uid_entry {
  36         uid_t uid;
  37         cputime_t utime;
  38         cputime_t stime;
  39         cputime_t active_utime;
  40         cputime_t active_stime;
  41         struct hlist_node hash;
  42 };
  43
  44 static struct uid_entry *find_uid_entry(uid_t uid)
  45 {
  46         struct uid_entry *uid_entry;
  47         hash_for_each_possible(hash_table, uid_entry, hash, uid) {
  48                 if (uid_entry->uid == uid)
  49                         return uid_entry;
  50         }
  51         return NULL;
  52 }
  53
  54 static struct uid_entry *find_or_register_uid(uid_t uid)
  55 {
  56         struct uid_entry *uid_entry;
  57
  58         uid_entry = find_uid_entry(uid);
  59         if (uid_entry)
  60                 return uid_entry;
  61
  62         uid_entry = kzalloc(sizeof(struct uid_entry), GFP_ATOMIC);
  63         if (!uid_entry)
  64                 return NULL;
  65
  66         uid_entry->uid = uid;
  67
  68         hash_add(hash_table, &uid_entry->hash, uid);
  69
  70         return uid_entry;
  71 }
  72
  73 static int uid_stat_show(struct seq_file *m, void *v)
  74 {
  75         struct uid_entry *uid_entry;
  76         struct task_struct *task;
  77         cputime_t utime;
  78         cputime_t stime;
  79         unsigned long bkt;
  80
  81         mutex_lock(&uid_lock);
  82
  83         hash_for_each(hash_table, bkt, uid_entry, hash) {
  84                 uid_entry->active_stime = 0;
  85                 uid_entry->active_utime = 0;
  86         }
  87
  88         read_lock(&tasklist_lock);
  89         for_each_process(task) {
  90                 uid_entry = find_or_register_uid(from_kuid_munged(
  91                         current_user_ns(), task_uid(task)));
  92                 if (!uid_entry) {
  93                         read_unlock(&tasklist_lock);
  94                         mutex_unlock(&uid_lock);
  95                         pr_err("%s: failed to find the uid_entry for uid %d\n",
  96                                 __func__, from_kuid_munged(current_user_ns(),
  97                                 task_uid(task)));
  98                         return -ENOMEM;
  99                 }
 100                 task_cputime_adjusted(task, &utime, &stime);
 101                 uid_entry->active_utime += utime;
 102                 uid_entry->active_stime += stime;
 103         }
 104         read_unlock(&tasklist_lock);
 105
 106         hash_for_each(hash_table, bkt, uid_entry, hash) {
 107                 cputime_t total_utime = uid_entry->utime +
 108                                                         uid_entry->active_utime;
 109                 cputime_t total_stime = uid_entry->stime +
 110                                                         uid_entry->active_stime;
 111                 seq_printf(m, "%d: %u %u\n", uid_entry->uid,
 112                                                 cputime_to_usecs(total_utime),
 113                                                 cputime_to_usecs(total_stime));
 114         }
 115
 116         mutex_unlock(&uid_lock);
 117         return 0;
 118 }
 119
 120 static int uid_stat_open(struct inode *inode, struct file *file)
 121 {
 122         return single_open(file, uid_stat_show, PDE_DATA(inode));
 123 }
 124
 125 static const struct file_operations uid_stat_fops = {
 126         .open           = uid_stat_open,
 127         .read           = seq_read,
 128         .llseek         = seq_lseek,
 129         .release        = single_release,
 130 };
 131
 132 static int uid_remove_open(struct inode *inode, struct file *file)
 133 {
 134         return single_open(file, NULL, NULL);
 135 }
 136
 137 static ssize_t uid_remove_write(struct file *file,
 138                         const char __user *buffer, size_t count, loff_t *ppos)
 139 {
 140         struct uid_entry *uid_entry;
 141         struct hlist_node *tmp;
 142         char uids[128];
 143         char *start_uid, *end_uid = NULL;
 144         long int uid_start = 0, uid_end = 0;
 145
 146         if (count >= sizeof(uids))
 147                 count = sizeof(uids) - 1;
 148
 149         if (copy_from_user(uids, buffer, count))
 150                 return -EFAULT;
 151
 152         uids[count] = '\0';
 153         end_uid = uids;
 154         start_uid = strsep(&end_uid, "-");
 155
 156         if (!start_uid || !end_uid)
 157                 return -EINVAL;
 158
 159         if (kstrtol(start_uid, 10, &uid_start) != 0 ||
 160                 kstrtol(end_uid, 10, &uid_end) != 0) {
 161                 return -EINVAL;
 162         }
 163
 164         mutex_lock(&uid_lock);
 165
 166         for (; uid_start <= uid_end; uid_start++) {
 167                 hash_for_each_possible_safe(hash_table, uid_entry, tmp,
 168                                                         hash, uid_start) {
 169                         hash_del(&uid_entry->hash);
 170                         kfree(uid_entry);
 171                 }
 172         }
 173
 174         mutex_unlock(&uid_lock);
 175         return count;
 176 }
 177
 178 static const struct file_operations uid_remove_fops = {
 179         .open           = uid_remove_open,
 180         .release        = single_release,
 181         .write          = uid_remove_write,
 182 };
 183
 184 static int process_notifier(struct notifier_block *self,
 185                         unsigned long cmd, void *v)
 186 {
 187         struct task_struct *task = v;
 188         struct uid_entry *uid_entry;
 189         cputime_t utime, stime;
 190         uid_t uid;
 191
 192         if (!task)
 193                 return NOTIFY_OK;
 194
 195         mutex_lock(&uid_lock);
 196         uid = from_kuid_munged(current_user_ns(), task_uid(task));
 197         uid_entry = find_or_register_uid(uid);
 198         if (!uid_entry) {
 199                 pr_err("%s: failed to find uid %d\n", __func__, uid);
 200                 goto exit;
 201         }
 202
 203         task_cputime_adjusted(task, &utime, &stime);
 204         uid_entry->utime += utime;
 205         uid_entry->stime += stime;
 206
 207 exit:
 208         mutex_unlock(&uid_lock);
 209         return NOTIFY_OK;
 210 }
 211
 212 static struct notifier_block process_notifier_block = {
 213         .notifier_call  = process_notifier,
 214 };
 215
 216 static int __init proc_uid_cputime_init(void)
 217 {
 218         hash_init(hash_table);
 219
 220         parent = proc_mkdir("uid_cputime", NULL);
 221         if (!parent) {
 222                 pr_err("%s: failed to create proc entry\n", __func__);
 223                 return -ENOMEM;
 224         }
 225
 226         proc_create_data("remove_uid_range", S_IWUGO, parent, &uid_remove_fops,
 227                                         NULL);
 228
 229         proc_create_data("show_uid_stat", S_IRUGO, parent, &uid_stat_fops,
 230                                         NULL);
 231
 232         profile_event_register(PROFILE_TASK_EXIT, &process_notifier_block);
 233
 234         return 0;
 235 }
 236
 237 early_initcall(proc_uid_cputime_init);