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         struct hlist_bl_node *pos;
  53
  54         err = -EBUSY;
  55         if (unlikely(file->private_data))
  56                 goto out;
  57
  58         sb = NULL;
  59         /* don't use au_sbilist_lock() here */
  60         hlist_bl_lock(&au_sbilist);
  61         hlist_bl_for_each_entry(sbinfo, pos, &au_sbilist, si_list)
  62                 if (id == sysaufs_si_id(sbinfo)) {
  63                         kobject_get(&sbinfo->si_kobj);
  64                         sb = sbinfo->si_sb;
  65                         break;
  66                 }
  67         hlist_bl_unlock(&au_sbilist);
  68
  69         err = -EINVAL;
  70         if (unlikely(!sb))
  71                 goto out;
  72
  73         err = au_plink_maint_enter(sb);
  74         if (!err)
  75                 /* keep kobject_get() */
  76                 file->private_data = sbinfo;
  77         else
  78                 kobject_put(&sbinfo->si_kobj);
  79 out:
  80         return err;
  81 }
  82
  83 /*
  84  * Accept a valid "si=xxxx" only.
  85  * Once it is accepted successfully, accept "clean" too.
  86  */
  87 static ssize_t au_procfs_plm_write(struct file *file, const char __user *ubuf,
  88                                    size_t count, loff_t *ppos)
  89 {
  90         ssize_t err;
  91         unsigned long id;
  92         /* last newline is allowed */
  93         char buf[3 + sizeof(unsigned long) * 2 + 1];
  94
  95         err = -EACCES;
  96         if (unlikely(!capable(CAP_SYS_ADMIN)))
  97                 goto out;
  98
  99         err = -EINVAL;
 100         if (unlikely(count > sizeof(buf)))
 101                 goto out;
 102
 103         err = copy_from_user(buf, ubuf, count);
 104         if (unlikely(err)) {
 105                 err = -EFAULT;
 106                 goto out;
 107         }
 108         buf[count] = 0;
 109
 110         err = -EINVAL;
 111         if (!strcmp("clean", buf)) {
 112                 au_procfs_plm_write_clean(file);
 113                 goto out_success;
 114         } else if (unlikely(strncmp("si=", buf, 3)))
 115                 goto out;
 116
 117         err = kstrtoul(buf + 3, 16, &id);
 118         if (unlikely(err))
 119                 goto out;
 120
 121         err = au_procfs_plm_write_si(file, id);
 122         if (unlikely(err))
 123                 goto out;
 124
 125 out_success:
 126         err = count; /* success */
 127 out:
 128         return err;
 129 }
 130
 131 static const struct file_operations au_procfs_plm_fop = {
 132         .write          = au_procfs_plm_write,
 133         .release        = au_procfs_plm_release,
 134         .owner          = THIS_MODULE
 135 };
 136
 137 /* ---------------------------------------------------------------------- */
 138
 139 static struct proc_dir_entry *au_procfs_dir;
 140
 141 void au_procfs_fin(void)
 142 {
 143         remove_proc_entry(AUFS_PLINK_MAINT_NAME, au_procfs_dir);
 144         remove_proc_entry(AUFS_PLINK_MAINT_DIR, NULL);
 145 }
 146
 147 int __init au_procfs_init(void)
 148 {
 149         int err;
 150         struct proc_dir_entry *entry;
 151
 152         err = -ENOMEM;
 153         au_procfs_dir = proc_mkdir(AUFS_PLINK_MAINT_DIR, NULL);
 154         if (unlikely(!au_procfs_dir))
 155                 goto out;
 156
 157         entry = proc_create(AUFS_PLINK_MAINT_NAME, S_IFREG | S_IWUSR,
 158                             au_procfs_dir, &au_procfs_plm_fop);
 159         if (unlikely(!entry))
 160                 goto out_dir;
 161
 162         err = 0;
 163         goto out; /* success */
 164
 165
 166 out_dir:
 167         remove_proc_entry(AUFS_PLINK_MAINT_DIR, NULL);
 168 out:
 169         return err;
 170 }