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(task_uid(task));
  91                 if (!uid_entry) {
  92                         read_unlock(&tasklist_lock);
  93                         mutex_unlock(&uid_lock);
  94                         pr_err("%s: failed to find the uid_entry for uid %d\n",
  95                                                 __func__, task_uid(task));
  96                         return -ENOMEM;
  97                 }
  98                 task_cputime_adjusted(task, &utime, &stime);
  99                 uid_entry->active_utime += utime;
 100                 uid_entry->active_stime += stime;
 101         }
 102         read_unlock(&tasklist_lock);
 103
 104         hash_for_each(hash_table, bkt, uid_entry, hash) {
 105                 cputime_t total_utime = uid_entry->utime +
 106                                                         uid_entry->active_utime;
 107                 cputime_t total_stime = uid_entry->stime +
 108                                                         uid_entry->active_stime;
 109                 seq_printf(m, "%d: %u %u\n", uid_entry->uid,
 110                                                 cputime_to_usecs(total_utime),
 111                                                 cputime_to_usecs(total_stime));
 112         }
 113
 114         mutex_unlock(&uid_lock);
 115         return 0;
 116 }
 117
 118 static int uid_stat_open(struct inode *inode, struct file *file)
 119 {
 120         return single_open(file, uid_stat_show, PDE_DATA(inode));
 121 }
 122
 123 static const struct file_operations uid_stat_fops = {
 124         .open           = uid_stat_open,
 125         .read           = seq_read,
 126         .llseek         = seq_lseek,
 127         .release        = single_release,
 128 };
 129
 130 static int uid_remove_open(struct inode *inode, struct file *file)
 131 {
 132         return single_open(file, NULL, NULL);
 133 }
 134
 135 static ssize_t uid_remove_write(struct file *file,
 136                         const char __user *buffer, size_t count, loff_t *ppos)
 137 {
 138         struct uid_entry *uid_entry;
 139         struct hlist_node *tmp;
 140         char uids[128];
 141         char *start_uid, *end_uid = NULL;
 142         long int uid_start = 0, uid_end = 0;
 143
 144         if (count >= sizeof(uids))
 145                 count = sizeof(uids) - 1;
 146
 147         if (copy_from_user(uids, buffer, count))
 148                 return -EFAULT;
 149
 150         uids[count] = '\0';
 151         end_uid = uids;
 152         start_uid = strsep(&end_uid, "-");
 153
 154         if (!start_uid || !end_uid)
 155                 return -EINVAL;
 156
 157         if (kstrtol(start_uid, 10, &uid_start) != 0 ||
 158                 kstrtol(end_uid, 10, &uid_end) != 0) {
 159                 return -EINVAL;
 160         }
 161
 162         mutex_lock(&uid_lock);
 163
 164         for (; uid_start <= uid_end; uid_start++) {
 165                 hash_for_each_possible_safe(hash_table, uid_entry, tmp,
 166                                                         hash, uid_start) {
 167                         hash_del(&uid_entry->hash);
 168                         kfree(uid_entry);
 169                 }
 170         }
 171
 172         mutex_unlock(&uid_lock);
 173         return count;
 174 }
 175
 176 static const struct file_operations uid_remove_fops = {
 177         .open           = uid_remove_open,
 178         .release        = single_release,
 179         .write          = uid_remove_write,
 180 };
 181
 182 static int process_notifier(struct notifier_block *self,
 183                         unsigned long cmd, void *v)
 184 {
 185         struct task_struct *task = v;
 186         struct uid_entry *uid_entry;
 187         cputime_t utime, stime;
 188         uid_t uid;
 189
 190         if (!task)
 191                 return NOTIFY_OK;
 192
 193         mutex_lock(&uid_lock);
 194         uid = task_uid(task);
 195         uid_entry = find_or_register_uid(uid);
 196         if (!uid_entry) {
 197                 pr_err("%s: failed to find uid %d\n", __func__, uid);
 198                 goto exit;
 199         }
 200
 201         task_cputime_adjusted(task, &utime, &stime);
 202         uid_entry->utime += utime;
 203         uid_entry->stime += stime;
 204
 205 exit:
 206         mutex_unlock(&uid_lock);
 207         return NOTIFY_OK;
 208 }
 209
 210 static struct notifier_block process_notifier_block = {
 211         .notifier_call  = process_notifier,
 212 };
 213
 214 static int __init proc_uid_cputime_init(void)
 215 {
 216         hash_init(hash_table);
 217
 218         parent = proc_mkdir("uid_cputime", NULL);
 219         if (!parent) {
 220                 pr_err("%s: failed to create proc entry\n", __func__);
 221                 return -ENOMEM;
 222         }
 223
 224         proc_create_data("remove_uid_range", S_IWUGO, parent, &uid_remove_fops,
 225                                         NULL);
 226
 227         proc_create_data("show_uid_stat", S_IWUGO, parent, &uid_stat_fops,
 228                                         NULL);
 229
 230         profile_event_register(PROFILE_TASK_EXIT, &process_notifier_block);
 231
 232         return 0;
 233 }
 234
 235 early_initcall(proc_uid_cputime_init);