fs/aufs/procfs.c

   1 /*
   2  * Copyright (C) 2010-2017 Junjiro R. Okajima
   3  *
   4  * This program, aufs is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   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  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * procfs interfaces
  20  */
  21
  22 #include <linux/proc_fs.h>
  23 #include "aufs.h"
  24
  25 static int au_procfs_plm_release(struct inode *inode, struct file *file)
  26 {
  27         struct au_sbinfo *sbinfo;
  28
  29         sbinfo = file->private_data;
  30         if (sbinfo) {
  31                 au_plink_maint_leave(sbinfo);
  32                 kobject_put(&sbinfo->si_kobj);
  33         }
  34
  35         return 0;
  36 }
  37
  38 static void au_procfs_plm_write_clean(struct file *file)
  39 {
  40         struct au_sbinfo *sbinfo;
  41
  42         sbinfo = file->private_data;
  43         if (sbinfo)
  44                 au_plink_clean(sbinfo->si_sb, /*verbose*/0);
  45 }
  46
  47 static int au_procfs_plm_write_si(struct file *file, unsigned long id)
  48 {
  49         int err;
  50         struct super_block *sb;
  51         struct au_sbinfo *sbinfo;
  52
  53         err = -EBUSY;
  54         if (unlikely(file->private_data))
  55                 goto out;
  56
  57         sb = NULL;
  58         /* don't use au_sbilist_lock() here */
  59         spin_lock(&au_sbilist.spin);
  60         hlist_for_each_entry(sbinfo, &au_sbilist.head, si_list)
  61                 if (id == sysaufs_si_id(sbinfo)) {
  62                         kobject_get(&sbinfo->si_kobj);
  63                         sb = sbinfo->si_sb;
  64                         break;
  65                 }
  66         spin_unlock(&au_sbilist.spin);
  67
  68         err = -EINVAL;
  69         if (unlikely(!sb))
  70                 goto out;
  71
  72         err = au_plink_maint_enter(sb);
  73         if (!err)
  74                 /* keep kobject_get() */
  75                 file->private_data = sbinfo;
  76         else
  77                 kobject_put(&sbinfo->si_kobj);
  78 out:
  79         return err;
  80 }
  81
  82 /*
  83  * Accept a valid "si=xxxx" only.
  84  * Once it is accepted successfully, accept "clean" too.
  85  */
  86 static ssize_t au_procfs_plm_write(struct file *file, const char __user *ubuf,
  87                                    size_t count, loff_t *ppos)
  88 {
  89         ssize_t err;
  90         unsigned long id;
  91         /* last newline is allowed */
  92         char buf[3 + sizeof(unsigned long) * 2 + 1];
  93
  94         err = -EACCES;
  95         if (unlikely(!capable(CAP_SYS_ADMIN)))
  96                 goto out;
  97
  98         err = -EINVAL;
  99         if (unlikely(count > sizeof(buf)))
 100                 goto out;
 101
 102         err = copy_from_user(buf, ubuf, count);
 103         if (unlikely(err)) {
 104                 err = -EFAULT;
 105                 goto out;
 106         }
 107         buf[count] = 0;
 108
 109         err = -EINVAL;
 110         if (!strcmp("clean", buf)) {
 111                 au_procfs_plm_write_clean(file);
 112                 goto out_success;
 113         } else if (unlikely(strncmp("si=", buf, 3)))
 114                 goto out;
 115
 116         err = kstrtoul(buf + 3, 16, &id);
 117         if (unlikely(err))
 118                 goto out;
 119
 120         err = au_procfs_plm_write_si(file, id);
 121         if (unlikely(err))
 122                 goto out;
 123
 124 out_success:
 125         err = count; /* success */
 126 out:
 127         return err;
 128 }
 129
 130 static const struct file_operations au_procfs_plm_fop = {
 131         .write          = au_procfs_plm_write,
 132         .release        = au_procfs_plm_release,
 133         .owner          = THIS_MODULE
 134 };
 135
 136 /* ---------------------------------------------------------------------- */
 137
 138 static struct proc_dir_entry *au_procfs_dir;
 139
 140 void au_procfs_fin(void)
 141 {
 142         remove_proc_entry(AUFS_PLINK_MAINT_NAME, au_procfs_dir);
 143         remove_proc_entry(AUFS_PLINK_MAINT_DIR, NULL);
 144 }
 145
 146 int __init au_procfs_init(void)
 147 {
 148         int err;
 149         struct proc_dir_entry *entry;
 150
 151         err = -ENOMEM;
 152         au_procfs_dir = proc_mkdir(AUFS_PLINK_MAINT_DIR, NULL);
 153         if (unlikely(!au_procfs_dir))
 154                 goto out;
 155
 156         entry = proc_create(AUFS_PLINK_MAINT_NAME, S_IFREG | S_IWUSR,
 157                             au_procfs_dir, &au_procfs_plm_fop);
 158         if (unlikely(!entry))
 159                 goto out_dir;
 160
 161         err = 0;
 162         goto out; /* success */
 163
 164
 165 out_dir:
 166         remove_proc_entry(AUFS_PLINK_MAINT_DIR, NULL);
 167 out:
 168         return err;
 169 }