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
  24 static int vfs_fileid_debug_level = DBGC_VFS;
  25
  26 #undef DBGC_CLASS
  27 #define DBGC_CLASS vfs_fileid_debug_level
  28
  29 struct fileid_mount_entry {
  30         SMB_DEV_T device;
  31         const char *mnt_fsname;
  32         fsid_t fsid;
  33         uint64_t devid;
  34 };
  35
  36 struct fileid_handle_data {
  37         uint64_t (*device_mapping_fn)(struct fileid_handle_data *data,
  38                                       SMB_DEV_T dev);
  39         unsigned num_mount_entries;
  40         struct fileid_mount_entry *mount_entries;
  41 };
  42
  43 /* load all the mount entries from the mtab */
  44 static void fileid_load_mount_entries(struct fileid_handle_data *data)
  45 {
  46         FILE *f;
  47         struct mntent *m;
  48
  49         data->num_mount_entries = 0;
  50         TALLOC_FREE(data->mount_entries);
  51
  52         f = setmntent("/etc/mtab", "r");
  53         if (!f) return;
  54
  55         while ((m = getmntent(f))) {
  56                 struct stat st;
  57                 struct statfs sfs;
  58                 struct fileid_mount_entry *cur;
  59
  60                 if (stat(m->mnt_dir, &st) != 0) continue;
  61                 if (statfs(m->mnt_dir, &sfs) != 0) continue;
  62
  63                 if (strncmp(m->mnt_fsname, "/dev/", 5) == 0) {
  64                         m->mnt_fsname += 5;
  65                 }
  66
  67                 data->mount_entries = TALLOC_REALLOC_ARRAY(data,
  68                                                            data->mount_entries,
  69                                                            struct fileid_mount_entry,
  70                                                            data->num_mount_entries+1);
  71                 if (data->mount_entries == NULL) {
  72                         goto nomem;
  73                 }
  74
  75                 cur = &data->mount_entries[data->num_mount_entries];
  76                 cur->device     = st.st_dev;
  77                 cur->mnt_fsname = talloc_strdup(data->mount_entries,
  78                                                 m->mnt_fsname);
  79                 if (!cur->mnt_fsname) goto nomem;
  80                 cur->fsid       = sfs.f_fsid;
  81                 cur->devid      = (uint64_t)-1;
  82
  83                 data->num_mount_entries++;
  84         }
  85         endmntent(f);
  86         return;
  87
  88 nomem:
  89         if (f) endmntent(f);
  90
  91         data->num_mount_entries = 0;
  92         TALLOC_FREE(data->mount_entries);
  93
  94         return;
  95 }
  96
  97 /* find a mount entry given a dev_t */
  98 static struct fileid_mount_entry *fileid_find_mount_entry(struct fileid_handle_data *data,
  99                                                           SMB_DEV_T dev)
 100 {
 101         int i;
 102
 103         if (data->num_mount_entries == 0) {
 104                 fileid_load_mount_entries(data);
 105         }
 106         for (i=0;i<data->num_mount_entries;i++) {
 107                 if (data->mount_entries[i].device == dev) {
 108                         return &data->mount_entries[i];
 109                 }
 110         }
 111         /* 2nd pass after reloading */
 112         fileid_load_mount_entries(data);
 113         for (i=0;i<data->num_mount_entries;i++) {
 114                 if (data->mount_entries[i].device == dev) {
 115                         return &data->mount_entries[i];
 116                 }
 117         }
 118         return NULL;
 119 }
 120
 121
 122 /* a 64 bit hash, based on the one in tdb */
 123 static uint64_t fileid_uint64_hash(const uint8_t *s, size_t len)
 124 {
 125         uint64_t value; /* Used to compute the hash value.  */
 126         uint32_t i;     /* Used to cycle through random values. */
 127
 128         /* Set the initial value from the key size. */
 129         for (value = 0x238F13AFLL * len, i=0; i < len; i++)
 130                 value = (value + (s[i] << (i*5 % 24)));
 131
 132         return (1103515243LL * value + 12345LL);
 133 }
 134
 135 /* a device mapping using a fsname */
 136 static uint64_t fileid_device_mapping_fsname(struct fileid_handle_data *data,
 137                                              SMB_DEV_T dev)
 138 {
 139         struct fileid_mount_entry *m;
 140
 141         m = fileid_find_mount_entry(data, dev);
 142         if (!m) return dev;
 143
 144         if (m->devid == (uint64_t)-1) {
 145                 m->devid = fileid_uint64_hash((uint8_t *)m->mnt_fsname,
 146                                               strlen(m->mnt_fsname));
 147         }
 148
 149         return m->devid;
 150 }
 151
 152 /* device mapping functions using a fsid */
 153 static uint64_t fileid_device_mapping_fsid(struct fileid_handle_data *data,
 154                                            SMB_DEV_T dev)
 155 {
 156         struct fileid_mount_entry *m;
 157
 158         m = fileid_find_mount_entry(data, dev);
 159         if (!m) return dev;
 160
 161         if (m->devid == (uint64_t)-1) {
 162                 if (sizeof(fsid_t) > sizeof(uint64_t)) {
 163                         m->devid = fileid_uint64_hash((uint8_t *)&m->fsid,
 164                                                       sizeof(m->fsid));
 165                 } else {
 166                         union {
 167                                 uint64_t ret;
 168                                 fsid_t fsid;
 169                         } u;
 170                         ZERO_STRUCT(u);
 171                         u.fsid = m->fsid;
 172                         m->devid = u.ret;
 173                 }
 174         }
 175
 176         return m->devid;
 177 }
 178
 179 static int fileid_connect(struct vfs_handle_struct *handle,
 180                           const char *service, const char *user)
 181 {
 182         struct fileid_handle_data *data;
 183         const char *algorithm;
 184
 185         data = talloc_zero(handle->conn, struct fileid_handle_data);
 186         if (!data) {
 187                 DEBUG(0, ("talloc_zero() failed\n"));
 188                 return -1;
 189         }
 190
 191         /*
 192          * "fileid:mapping" is only here as fallback for old setups
 193          * "fileid:algorithm" is the option new setups should use
 194          */
 195         algorithm = lp_parm_const_string(SNUM(handle->conn),
 196                                          "fileid", "mapping",
 197                                          "fsname");
 198         algorithm = lp_parm_const_string(SNUM(handle->conn),
 199                                          "fileid", "algorithm",
 200                                          algorithm);
 201         if (strcmp("fsname", algorithm) == 0) {
 202                 data->device_mapping_fn = fileid_device_mapping_fsname;
 203         } else if (strcmp("fsid", algorithm) == 0) {
 204                 data->device_mapping_fn = fileid_device_mapping_fsid;
 205         } else {
 206                 DEBUG(0,("fileid_connect(): unknown algorithm[%s]\n", algorithm));
 207                 return -1;
 208         }
 209
 210         SMB_VFS_HANDLE_SET_DATA(handle, data, NULL,
 211                                 struct fileid_handle_data,
 212                                 return -1);
 213
 214         DEBUG(10, ("fileid_connect(): connect to service[%s] with algorithm[%s]\n",
 215                 service, algorithm));
 216
 217         return SMB_VFS_NEXT_CONNECT(handle, service, user);
 218 }
 219
 220 static void fileid_disconnect(struct vfs_handle_struct *handle)
 221 {
 222         DEBUG(10,("fileid_disconnect() connect to service[%s].\n",
 223                 lp_servicename(SNUM(handle->conn))));
 224
 225         SMB_VFS_NEXT_DISCONNECT(handle);
 226 }
 227
 228 static struct file_id fileid_file_id_create(struct vfs_handle_struct *handle,
 229                                             const SMB_STRUCT_STAT *sbuf)
 230 {
 231         struct fileid_handle_data *data;
 232         struct file_id id;
 233
 234         ZERO_STRUCT(id);
 235
 236         SMB_VFS_HANDLE_GET_DATA(handle, data,
 237                                 struct fileid_handle_data,
 238                                 return id);
 239
 240         id.devid        = data->device_mapping_fn(data, sbuf->st_ex_dev);
 241         id.inode        = sbuf->st_ex_ino;
 242
 243         return id;
 244 }
 245
 246 static struct vfs_fn_pointers vfs_fileid_fns = {
 247         .connect_fn = fileid_connect,
 248         .disconnect = fileid_disconnect,
 249         .file_id_create = fileid_file_id_create
 250 };
 251
 252 NTSTATUS vfs_fileid_init(void);
 253 NTSTATUS vfs_fileid_init(void)
 254 {
 255         NTSTATUS ret;
 256
 257         ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "fileid",
 258                                &vfs_fileid_fns);
 259         if (!NT_STATUS_IS_OK(ret)) {
 260                 return ret;
 261         }
 262
 263         vfs_fileid_debug_level = debug_add_class("fileid");
 264         if (vfs_fileid_debug_level == -1) {
 265                 vfs_fileid_debug_level = DBGC_VFS;
 266                 DEBUG(0, ("vfs_fileid: Couldn't register custom debugging class!\n"));
 267         } else {
 268                 DEBUG(10, ("vfs_fileid: Debug class number of 'fileid': %d\n", vfs_fileid_debug_level));
 269         }
 270
 271         return ret;
 272 }