source3/modules/vfs_fileid.c

   1 /*
   2  * VFS module to alter the algorithm to calculate
   3  * the struct file_id used as key for the share mode
   4  * and byte range locking db's.
   5  *
   6  * Copyright (C) 2007, Stefan Metzmacher
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 3 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include "includes.h"
  23 #include "smbd/smbd.h"
  24 #include "system/filesys.h"
  25
  26 static int vfs_fileid_debug_level = DBGC_VFS;
  27
  28 #undef DBGC_CLASS
  29 #define DBGC_CLASS vfs_fileid_debug_level
  30
  31 struct fileid_mount_entry {
  32         SMB_DEV_T device;
  33         const char *mnt_fsname;
  34         fsid_t fsid;
  35         uint64_t devid;
  36 };
  37
  38 struct fileid_handle_data {
  39         uint64_t (*device_mapping_fn)(struct fileid_handle_data *data,
  40                                       SMB_DEV_T dev);
  41         unsigned num_mount_entries;
  42         struct fileid_mount_entry *mount_entries;
  43 };
  44
  45 /* load all the mount entries from the mtab */
  46 static void fileid_load_mount_entries(struct fileid_handle_data *data)
  47 {
  48         FILE *f;
  49         struct mntent *m;
  50
  51         data->num_mount_entries = 0;
  52         TALLOC_FREE(data->mount_entries);
  53
  54         f = setmntent("/etc/mtab", "r");
  55         if (!f) return;
  56
  57         while ((m = getmntent(f))) {
  58                 struct stat st;
  59                 struct statfs sfs;
  60                 struct fileid_mount_entry *cur;
  61
  62                 if (stat(m->mnt_dir, &st) != 0) continue;
  63                 if (statfs(m->mnt_dir, &sfs) != 0) continue;
  64
  65                 if (strncmp(m->mnt_fsname, "/dev/", 5) == 0) {
  66                         m->mnt_fsname += 5;
  67                 }
  68
  69                 data->mount_entries = talloc_realloc(data,
  70                                                            data->mount_entries,
  71                                                            struct fileid_mount_entry,
  72                                                            data->num_mount_entries+1);
  73                 if (data->mount_entries == NULL) {
  74                         goto nomem;
  75                 }
  76
  77                 cur = &data->mount_entries[data->num_mount_entries];
  78                 cur->device     = st.st_dev;
  79                 cur->mnt_fsname = talloc_strdup(data->mount_entries,
  80                                                 m->mnt_fsname);
  81                 if (!cur->mnt_fsname) goto nomem;
  82                 cur->fsid       = sfs.f_fsid;
  83                 cur->devid      = (uint64_t)-1;
  84
  85                 data->num_mount_entries++;
  86         }
  87         endmntent(f);
  88         return;
  89
  90 nomem:
  91         if (f) endmntent(f);
  92
  93         data->num_mount_entries = 0;
  94         TALLOC_FREE(data->mount_entries);
  95
  96         return;
  97 }
  98
  99 /* find a mount entry given a dev_t */
 100 static struct fileid_mount_entry *fileid_find_mount_entry(struct fileid_handle_data *data,
 101                                                           SMB_DEV_T dev)
 102 {
 103         int i;
 104
 105         if (data->num_mount_entries == 0) {
 106                 fileid_load_mount_entries(data);
 107         }
 108         for (i=0;i<data->num_mount_entries;i++) {
 109                 if (data->mount_entries[i].device == dev) {
 110                         return &data->mount_entries[i];
 111                 }
 112         }
 113         /* 2nd pass after reloading */
 114         fileid_load_mount_entries(data);
 115         for (i=0;i<data->num_mount_entries;i++) {
 116                 if (data->mount_entries[i].device == dev) {
 117                         return &data->mount_entries[i];
 118                 }
 119         }
 120         return NULL;
 121 }
 122
 123
 124 /* a 64 bit hash, based on the one in tdb */
 125 static uint64_t fileid_uint64_hash(const uint8_t *s, size_t len)
 126 {
 127         uint64_t value; /* Used to compute the hash value.  */
 128         uint32_t i;     /* Used to cycle through random values. */
 129
 130         /* Set the initial value from the key size. */
 131         for (value = 0x238F13AFLL * len, i=0; i < len; i++)
 132                 value = (value + (s[i] << (i*5 % 24)));
 133
 134         return (1103515243LL * value + 12345LL);
 135 }
 136
 137 /* a device mapping using a fsname */
 138 static uint64_t fileid_device_mapping_fsname(struct fileid_handle_data *data,
 139                                              SMB_DEV_T dev)
 140 {
 141         struct fileid_mount_entry *m;
 142
 143         m = fileid_find_mount_entry(data, dev);
 144         if (!m) return dev;
 145
 146         if (m->devid == (uint64_t)-1) {
 147                 m->devid = fileid_uint64_hash((const uint8_t *)m->mnt_fsname,
 148                                               strlen(m->mnt_fsname));
 149         }
 150
 151         return m->devid;
 152 }
 153
 154 /* device mapping functions using a fsid */
 155 static uint64_t fileid_device_mapping_fsid(struct fileid_handle_data *data,
 156                                            SMB_DEV_T dev)
 157 {
 158         struct fileid_mount_entry *m;
 159
 160         m = fileid_find_mount_entry(data, dev);
 161         if (!m) return dev;
 162
 163         if (m->devid == (uint64_t)-1) {
 164                 if (sizeof(fsid_t) > sizeof(uint64_t)) {
 165                         m->devid = fileid_uint64_hash((uint8_t *)&m->fsid,
 166                                                       sizeof(m->fsid));
 167                 } else {
 168                         union {
 169                                 uint64_t ret;
 170                                 fsid_t fsid;
 171                         } u;
 172                         ZERO_STRUCT(u);
 173                         u.fsid = m->fsid;
 174                         m->devid = u.ret;
 175                 }
 176         }
 177
 178         return m->devid;
 179 }
 180
 181 static int fileid_connect(struct vfs_handle_struct *handle,
 182                           const char *service, const char *user)
 183 {
 184         struct fileid_handle_data *data;
 185         const char *algorithm;
 186         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 187
 188         if (ret < 0) {
 189                 return ret;
 190         }
 191
 192         data = talloc_zero(handle->conn, struct fileid_handle_data);
 193         if (!data) {
 194                 SMB_VFS_NEXT_DISCONNECT(handle);
 195                 DEBUG(0, ("talloc_zero() failed\n"));
 196                 return -1;
 197         }
 198
 199         /*
 200          * "fileid:mapping" is only here as fallback for old setups
 201          * "fileid:algorithm" is the option new setups should use
 202          */
 203         algorithm = lp_parm_const_string(SNUM(handle->conn),
 204                                          "fileid", "mapping",
 205                                          "fsname");
 206         algorithm = lp_parm_const_string(SNUM(handle->conn),
 207                                          "fileid", "algorithm",
 208                                          algorithm);
 209         if (strcmp("fsname", algorithm) == 0) {
 210                 data->device_mapping_fn = fileid_device_mapping_fsname;
 211         } else if (strcmp("fsid", algorithm) == 0) {
 212                 data->device_mapping_fn = fileid_device_mapping_fsid;
 213         } else {
 214                 SMB_VFS_NEXT_DISCONNECT(handle);
 215                 DEBUG(0,("fileid_connect(): unknown algorithm[%s]\n", algorithm));
 216                 return -1;
 217         }
 218
 219         SMB_VFS_HANDLE_SET_DATA(handle, data, NULL,
 220                                 struct fileid_handle_data,
 221                                 return -1);
 222
 223         DEBUG(10, ("fileid_connect(): connect to service[%s] with algorithm[%s]\n",
 224                 service, algorithm));
 225
 226         return 0;
 227 }
 228
 229 static void fileid_disconnect(struct vfs_handle_struct *handle)
 230 {
 231         DEBUG(10,("fileid_disconnect() connect to service[%s].\n",
 232                 lp_servicename(SNUM(handle->conn))));
 233
 234         SMB_VFS_NEXT_DISCONNECT(handle);
 235 }
 236
 237 static struct file_id fileid_file_id_create(struct vfs_handle_struct *handle,
 238                                             const SMB_STRUCT_STAT *sbuf)
 239 {
 240         struct fileid_handle_data *data;
 241         struct file_id id;
 242
 243         ZERO_STRUCT(id);
 244
 245         SMB_VFS_HANDLE_GET_DATA(handle, data,
 246                                 struct fileid_handle_data,
 247                                 return id);
 248
 249         id.devid        = data->device_mapping_fn(data, sbuf->st_ex_dev);
 250         id.inode        = sbuf->st_ex_ino;
 251
 252         return id;
 253 }
 254
 255 static struct vfs_fn_pointers vfs_fileid_fns = {
 256         .connect_fn = fileid_connect,
 257         .disconnect_fn = fileid_disconnect,
 258         .file_id_create_fn = fileid_file_id_create
 259 };
 260
 261 NTSTATUS vfs_fileid_init(void);
 262 NTSTATUS vfs_fileid_init(void)
 263 {
 264         NTSTATUS ret;
 265
 266         ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "fileid",
 267                                &vfs_fileid_fns);
 268         if (!NT_STATUS_IS_OK(ret)) {
 269                 return ret;
 270         }
 271
 272         vfs_fileid_debug_level = debug_add_class("fileid");
 273         if (vfs_fileid_debug_level == -1) {
 274                 vfs_fileid_debug_level = DBGC_VFS;
 275                 DEBUG(0, ("vfs_fileid: Couldn't register custom debugging class!\n"));
 276         } else {
 277                 DEBUG(10, ("vfs_fileid: Debug class number of 'fileid': %d\n", vfs_fileid_debug_level));
 278         }
 279
 280         return ret;
 281 }