block/cmd-filter.c

   1 /*
   2  * Copyright 2004 Peter M. Jones <pjones@redhat.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *
  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 Licens
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
  17  *
  18  */
  19
  20 #include <linux/list.h>
  21 #include <linux/genhd.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/parser.h>
  24 #include <linux/capability.h>
  25 #include <linux/bitops.h>
  26
  27 #include <scsi/scsi.h>
  28 #include <linux/cdrom.h>
  29
  30 int blk_cmd_filter_verify_command(struct blk_scsi_cmd_filter *filter,
  31                                   unsigned char *cmd, mode_t *f_mode)
  32 {
  33         /* root can do any command. */
  34         if (capable(CAP_SYS_RAWIO))
  35                 return 0;
  36
  37         /* if there's no filter set, assume we're filtering everything out */
  38         if (!filter)
  39                 return -EPERM;
  40
  41         /* Anybody who can open the device can do a read-safe command */
  42         if (test_bit(cmd[0], filter->read_ok))
  43                 return 0;
  44
  45         /* Write-safe commands require a writable open */
  46         if (test_bit(cmd[0], filter->write_ok) && (*f_mode & FMODE_WRITE))
  47                 return 0;
  48
  49         return -EPERM;
  50 }
  51 EXPORT_SYMBOL(blk_cmd_filter_verify_command);
  52
  53 int blk_verify_command(struct file *file, unsigned char *cmd)
  54 {
  55         struct gendisk *disk;
  56         struct inode *inode;
  57
  58         if (!file)
  59                 return -EINVAL;
  60
  61         inode = file->f_dentry->d_inode;
  62         if (!inode)
  63                 return -EINVAL;
  64
  65         disk = inode->i_bdev->bd_disk;
  66
  67         return blk_cmd_filter_verify_command(&disk->cmd_filter,
  68                                                  cmd, &file->f_mode);
  69 }
  70 EXPORT_SYMBOL(blk_verify_command);
  71
  72 /* and now, the sysfs stuff */
  73 static ssize_t rcf_cmds_show(struct blk_scsi_cmd_filter *filter, char *page,
  74                              int rw)
  75 {
  76         char *npage = page;
  77         unsigned long *okbits;
  78         int i;
  79
  80         if (rw == READ)
  81                 okbits = filter->read_ok;
  82         else
  83                 okbits = filter->write_ok;
  84
  85         for (i = 0; i < BLK_SCSI_MAX_CMDS; i++) {
  86                 if (test_bit(i, okbits)) {
  87                         sprintf(npage, "%02x", i);
  88                         npage += 2;
  89                         if (i < BLK_SCSI_MAX_CMDS - 1)
  90                                 sprintf(npage++, " ");
  91                 }
  92         }
  93
  94         if (npage != page)
  95                 npage += sprintf(npage, "\n");
  96
  97         return npage - page;
  98 }
  99
 100 static ssize_t rcf_readcmds_show(struct blk_scsi_cmd_filter *filter, char *page)
 101 {
 102         return rcf_cmds_show(filter, page, READ);
 103 }
 104
 105 static ssize_t rcf_writecmds_show(struct blk_scsi_cmd_filter *filter,
 106                                  char *page)
 107 {
 108         return rcf_cmds_show(filter, page, WRITE);
 109 }
 110
 111 static ssize_t rcf_cmds_store(struct blk_scsi_cmd_filter *filter,
 112                               const char *page, size_t count, int rw)
 113 {
 114         ssize_t ret = 0;
 115         unsigned long okbits[BLK_SCSI_CMD_PER_LONG], *target_okbits;
 116         int cmd, status, len;
 117         substring_t ss;
 118
 119         memset(&okbits, 0, sizeof(okbits));
 120
 121         for (len = strlen(page); len > 0; len -= 3) {
 122                 if (len < 2)
 123                         break;
 124                 ss.from = (char *) page + ret;
 125                 ss.to = (char *) page + ret + 2;
 126                 ret += 3;
 127                 status = match_hex(&ss, &cmd);
 128                 /* either of these cases means invalid input, so do nothing. */
 129                 if (status || cmd >= BLK_SCSI_MAX_CMDS)
 130                         return -EINVAL;
 131
 132                 __set_bit(cmd, okbits);
 133         }
 134
 135         if (rw == READ)
 136                 target_okbits = filter->read_ok;
 137         else
 138                 target_okbits = filter->write_ok;
 139
 140         memmove(target_okbits, okbits, sizeof(okbits));
 141         return count;
 142 }
 143
 144 static ssize_t rcf_readcmds_store(struct blk_scsi_cmd_filter *filter,
 145                                   const char *page, size_t count)
 146 {
 147         return rcf_cmds_store(filter, page, count, READ);
 148 }
 149
 150 static ssize_t rcf_writecmds_store(struct blk_scsi_cmd_filter *filter,
 151                                    const char *page, size_t count)
 152 {
 153         return rcf_cmds_store(filter, page, count, WRITE);
 154 }
 155
 156 struct rcf_sysfs_entry {
 157         struct attribute attr;
 158         ssize_t (*show)(struct blk_scsi_cmd_filter *, char *);
 159         ssize_t (*store)(struct blk_scsi_cmd_filter *, const char *, size_t);
 160 };
 161
 162 static struct rcf_sysfs_entry rcf_readcmds_entry = {
 163         .attr = { .name = "read_table", .mode = S_IRUGO | S_IWUSR },
 164         .show = rcf_readcmds_show,
 165         .store = rcf_readcmds_store,
 166 };
 167
 168 static struct rcf_sysfs_entry rcf_writecmds_entry = {
 169         .attr = {.name = "write_table", .mode = S_IRUGO | S_IWUSR },
 170         .show = rcf_writecmds_show,
 171         .store = rcf_writecmds_store,
 172 };
 173
 174 static struct attribute *default_attrs[] = {
 175         &rcf_readcmds_entry.attr,
 176         &rcf_writecmds_entry.attr,
 177         NULL,
 178 };
 179
 180 #define to_rcf(atr) container_of((atr), struct rcf_sysfs_entry, attr)
 181
 182 static ssize_t
 183 rcf_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 184 {
 185         struct rcf_sysfs_entry *entry = to_rcf(attr);
 186         struct blk_scsi_cmd_filter *filter;
 187
 188         filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
 189         if (entry->show)
 190                 return entry->show(filter, page);
 191
 192         return 0;
 193 }
 194
 195 static ssize_t
 196 rcf_attr_store(struct kobject *kobj, struct attribute *attr,
 197                         const char *page, size_t length)
 198 {
 199         struct rcf_sysfs_entry *entry = to_rcf(attr);
 200         struct blk_scsi_cmd_filter *filter;
 201
 202         if (!capable(CAP_SYS_RAWIO))
 203                 return -EPERM;
 204
 205         if (!entry->store)
 206                 return -EINVAL;
 207
 208         filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
 209         return entry->store(filter, page, length);
 210 }
 211
 212 static struct sysfs_ops rcf_sysfs_ops = {
 213         .show = rcf_attr_show,
 214         .store = rcf_attr_store,
 215 };
 216
 217 static struct kobj_type rcf_ktype = {
 218         .sysfs_ops = &rcf_sysfs_ops,
 219         .default_attrs = default_attrs,
 220 };
 221
 222 static void rcf_set_defaults(struct blk_scsi_cmd_filter *filter)
 223 {
 224         /* Basic read-only commands */
 225         __set_bit(TEST_UNIT_READY, filter->read_ok);
 226         __set_bit(REQUEST_SENSE, filter->read_ok);
 227         __set_bit(READ_6, filter->read_ok);
 228         __set_bit(READ_10, filter->read_ok);
 229         __set_bit(READ_12, filter->read_ok);
 230         __set_bit(READ_16, filter->read_ok);
 231         __set_bit(READ_BUFFER, filter->read_ok);
 232         __set_bit(READ_DEFECT_DATA, filter->read_ok);
 233         __set_bit(READ_LONG, filter->read_ok);
 234         __set_bit(INQUIRY, filter->read_ok);
 235         __set_bit(MODE_SENSE, filter->read_ok);
 236         __set_bit(MODE_SENSE_10, filter->read_ok);
 237         __set_bit(LOG_SENSE, filter->read_ok);
 238         __set_bit(START_STOP, filter->read_ok);
 239         __set_bit(GPCMD_VERIFY_10, filter->read_ok);
 240         __set_bit(VERIFY_16, filter->read_ok);
 241         __set_bit(GPCMD_READ_BUFFER_CAPACITY, filter->read_ok);
 242
 243         /* Audio CD commands */
 244         __set_bit(GPCMD_PLAY_CD, filter->read_ok);
 245         __set_bit(GPCMD_PLAY_AUDIO_10, filter->read_ok);
 246         __set_bit(GPCMD_PLAY_AUDIO_MSF, filter->read_ok);
 247         __set_bit(GPCMD_PLAY_AUDIO_TI, filter->read_ok);
 248         __set_bit(GPCMD_PAUSE_RESUME, filter->read_ok);
 249
 250         /* CD/DVD data reading */
 251         __set_bit(GPCMD_READ_CD, filter->read_ok);
 252         __set_bit(GPCMD_READ_CD_MSF, filter->read_ok);
 253         __set_bit(GPCMD_READ_DISC_INFO, filter->read_ok);
 254         __set_bit(GPCMD_READ_CDVD_CAPACITY, filter->read_ok);
 255         __set_bit(GPCMD_READ_DVD_STRUCTURE, filter->read_ok);
 256         __set_bit(GPCMD_READ_HEADER, filter->read_ok);
 257         __set_bit(GPCMD_READ_TRACK_RZONE_INFO, filter->read_ok);
 258         __set_bit(GPCMD_READ_SUBCHANNEL, filter->read_ok);
 259         __set_bit(GPCMD_READ_TOC_PMA_ATIP, filter->read_ok);
 260         __set_bit(GPCMD_REPORT_KEY, filter->read_ok);
 261         __set_bit(GPCMD_SCAN, filter->read_ok);
 262         __set_bit(GPCMD_GET_CONFIGURATION, filter->read_ok);
 263         __set_bit(GPCMD_READ_FORMAT_CAPACITIES, filter->read_ok);
 264         __set_bit(GPCMD_GET_EVENT_STATUS_NOTIFICATION, filter->read_ok);
 265         __set_bit(GPCMD_GET_PERFORMANCE, filter->read_ok);
 266         __set_bit(GPCMD_SEEK, filter->read_ok);
 267         __set_bit(GPCMD_STOP_PLAY_SCAN, filter->read_ok);
 268
 269         /* Basic writing commands */
 270         __set_bit(WRITE_6, filter->write_ok);
 271         __set_bit(WRITE_10, filter->write_ok);
 272         __set_bit(WRITE_VERIFY, filter->write_ok);
 273         __set_bit(WRITE_12, filter->write_ok);
 274         __set_bit(WRITE_VERIFY_12, filter->write_ok);
 275         __set_bit(WRITE_16, filter->write_ok);
 276         __set_bit(WRITE_LONG, filter->write_ok);
 277         __set_bit(WRITE_LONG_2, filter->write_ok);
 278         __set_bit(ERASE, filter->write_ok);
 279         __set_bit(GPCMD_MODE_SELECT_10, filter->write_ok);
 280         __set_bit(MODE_SELECT, filter->write_ok);
 281         __set_bit(LOG_SELECT, filter->write_ok);
 282         __set_bit(GPCMD_BLANK, filter->write_ok);
 283         __set_bit(GPCMD_CLOSE_TRACK, filter->write_ok);
 284         __set_bit(GPCMD_FLUSH_CACHE, filter->write_ok);
 285         __set_bit(GPCMD_FORMAT_UNIT, filter->write_ok);
 286         __set_bit(GPCMD_REPAIR_RZONE_TRACK, filter->write_ok);
 287         __set_bit(GPCMD_RESERVE_RZONE_TRACK, filter->write_ok);
 288         __set_bit(GPCMD_SEND_DVD_STRUCTURE, filter->write_ok);
 289         __set_bit(GPCMD_SEND_EVENT, filter->write_ok);
 290         __set_bit(GPCMD_SEND_KEY, filter->write_ok);
 291         __set_bit(GPCMD_SEND_OPC, filter->write_ok);
 292         __set_bit(GPCMD_SEND_CUE_SHEET, filter->write_ok);
 293         __set_bit(GPCMD_SET_SPEED, filter->write_ok);
 294         __set_bit(GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL, filter->write_ok);
 295         __set_bit(GPCMD_LOAD_UNLOAD, filter->write_ok);
 296         __set_bit(GPCMD_SET_STREAMING, filter->write_ok);
 297 }
 298
 299 int blk_register_filter(struct gendisk *disk)
 300 {
 301         int ret;
 302         struct blk_scsi_cmd_filter *filter = &disk->cmd_filter;
 303         struct kobject *parent = kobject_get(disk->holder_dir->parent);
 304
 305         if (!parent)
 306                 return -ENODEV;
 307
 308         ret = kobject_init_and_add(&filter->kobj, &rcf_ktype, parent,
 309                                  "%s", "cmd_filter");
 310
 311         if (ret < 0)
 312                 return ret;
 313
 314         rcf_set_defaults(filter);
 315         return 0;
 316 }
 317
 318 void blk_unregister_filter(struct gendisk *disk)
 319 {
 320         struct blk_scsi_cmd_filter *filter = &disk->cmd_filter;
 321
 322         kobject_put(&filter->kobj);
 323         kobject_put(disk->holder_dir->parent);
 324 }
 325