uidlist.c

   1 /*
   2  * Handle the mapping of uid/gid and user/group names between systems.
   3  *
   4  * Copyright (C) 1996 Andrew Tridgell
   5  * Copyright (C) 1996 Paul Mackerras
   6  * Copyright (C) 2004-2008 Wayne Davison
   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 along
  19  * with this program; if not, visit the http://fsf.org website.
  20  */
  21
  22 /* If the source username/group does not exist on the target then use
  23  * the numeric IDs.  Never do any mapping for uid=0 or gid=0 as these
  24  * are special. */
  25
  26 #include "rsync.h"
  27 #include "io.h"
  28
  29 extern int verbose;
  30 extern int am_root;
  31 extern int preserve_uid;
  32 extern int preserve_gid;
  33 extern int preserve_acls;
  34 extern int numeric_ids;
  35
  36 #ifdef HAVE_GETGROUPS
  37 # ifndef GETGROUPS_T
  38 #  define GETGROUPS_T gid_t
  39 # endif
  40 #endif
  41
  42 #define GID_NONE ((gid_t)-1)
  43
  44 struct idlist {
  45         struct idlist *next;
  46         const char *name;
  47         id_t id, id2;
  48         uint16 flags;
  49 };
  50
  51 static struct idlist *uidlist;
  52 static struct idlist *gidlist;
  53
  54 static struct idlist *add_to_list(struct idlist **root, id_t id, const char *name,
  55                                   id_t id2, uint16 flags)
  56 {
  57         struct idlist *node = new(struct idlist);
  58         if (!node)
  59                 out_of_memory("add_to_list");
  60         node->next = *root;
  61         node->name = name;
  62         node->id = id;
  63         node->id2 = id2;
  64         node->flags = flags;
  65         *root = node;
  66         return node;
  67 }
  68
  69 /* turn a uid into a user name */
  70 static const char *uid_to_name(uid_t uid)
  71 {
  72         struct passwd *pass = getpwuid(uid);
  73         if (pass)
  74                 return strdup(pass->pw_name);
  75         return NULL;
  76 }
  77
  78 /* turn a gid into a group name */
  79 static const char *gid_to_name(gid_t gid)
  80 {
  81         struct group *grp = getgrgid(gid);
  82         if (grp)
  83                 return strdup(grp->gr_name);
  84         return NULL;
  85 }
  86
  87 static uid_t map_uid(uid_t id, const char *name)
  88 {
  89         uid_t uid;
  90         if (id != 0 && name_to_uid(name, &uid))
  91                 return uid;
  92         return id;
  93 }
  94
  95 static gid_t map_gid(gid_t id, const char *name)
  96 {
  97         gid_t gid;
  98         if (id != 0 && name_to_gid(name, &gid))
  99                 return gid;
 100         return id;
 101 }
 102
 103 static int is_in_group(gid_t gid)
 104 {
 105 #ifdef HAVE_GETGROUPS
 106         static gid_t last_in = GID_NONE, last_out;
 107         static int ngroups = -2;
 108         static GETGROUPS_T *gidset;
 109         int n;
 110
 111         if (gid == last_in)
 112                 return last_out;
 113         if (ngroups < -1) {
 114                 gid_t mygid = MY_GID();
 115                 if ((ngroups = getgroups(0, NULL)) < 0)
 116                         ngroups = 0;
 117                 gidset = new_array(GETGROUPS_T, ngroups+1);
 118                 if (!gidset)
 119                         out_of_memory("is_in_group");
 120                 if (ngroups > 0)
 121                         ngroups = getgroups(ngroups, gidset);
 122                 /* The default gid might not be in the list on some systems. */
 123                 for (n = 0; n < ngroups; n++) {
 124                         if (gidset[n] == mygid)
 125                                 break;
 126                 }
 127                 if (n == ngroups)
 128                         gidset[ngroups++] = mygid;
 129                 if (verbose > 3) {
 130                         int pos;
 131                         char *gidbuf = new_array(char, ngroups*21+32);
 132                         if (!gidbuf)
 133                                 out_of_memory("is_in_group");
 134                         pos = snprintf(gidbuf, 32, "process has %d gid%s: ",
 135                                        ngroups, ngroups == 1? "" : "s");
 136                         for (n = 0; n < ngroups; n++) {
 137                                 pos += snprintf(gidbuf+pos, 21, " %d", (int)gidset[n]);
 138                         }
 139                         rprintf(FINFO, "%s\n", gidbuf);
 140                         free(gidbuf);
 141                 }
 142         }
 143
 144         last_in = gid;
 145         for (n = 0; n < ngroups; n++) {
 146                 if (gidset[n] == gid)
 147                         return last_out = 1;
 148         }
 149         return last_out = 0;
 150
 151 #else
 152         static gid_t mygid = GID_NONE;
 153         if (mygid == GID_NONE) {
 154                 mygid = MY_GID();
 155                 if (verbose > 3)
 156                         rprintf(FINFO, "process has gid %u\n", (unsigned)mygid);
 157         }
 158         return gid == mygid;
 159 #endif
 160 }
 161
 162 /* Add a uid to the list of uids.  Only called on receiving side. */
 163 static struct idlist *recv_add_uid(uid_t id, const char *name)
 164 {
 165         uid_t id2 = name ? map_uid(id, name) : id;
 166         struct idlist *node;
 167
 168         node = add_to_list(&uidlist, id, name, id2, 0);
 169
 170         if (verbose > 3) {
 171                 rprintf(FINFO, "uid %u(%s) maps to %u\n",
 172                         (unsigned)id, name ? name : "", (unsigned)id2);
 173         }
 174
 175         return node;
 176 }
 177
 178 /* Add a gid to the list of gids.  Only called on receiving side. */
 179 static struct idlist *recv_add_gid(gid_t id, const char *name)
 180 {
 181         gid_t id2 = name ? map_gid(id, name) : id;
 182         struct idlist *node;
 183
 184         node = add_to_list(&gidlist, id, name, id2,
 185                 !am_root && !is_in_group(id2) ? FLAG_SKIP_GROUP : 0);
 186
 187         if (verbose > 3) {
 188                 rprintf(FINFO, "gid %u(%s) maps to %u\n",
 189                         (unsigned)id, name ? name : "", (unsigned)id2);
 190         }
 191
 192         return node;
 193 }
 194
 195 /* this function is a definate candidate for a faster algorithm */
 196 uid_t match_uid(uid_t uid)
 197 {
 198         static uid_t last_in, last_out;
 199         struct idlist *list;
 200
 201         if (uid == 0)
 202                 return 0;
 203
 204         if (uid == last_in)
 205                 return last_out;
 206
 207         last_in = uid;
 208
 209         for (list = uidlist; list; list = list->next) {
 210                 if (list->id == uid)
 211                         return last_out = list->id2;
 212         }
 213
 214         return last_out = uid;
 215 }
 216
 217 gid_t match_gid(gid_t gid, uint16 *flags_ptr)
 218 {
 219         static struct idlist *last = NULL;
 220         struct idlist *list;
 221
 222         if (last && gid == last->id)
 223                 list = last;
 224         else {
 225                 for (list = gidlist; list; list = list->next) {
 226                         if (list->id == gid)
 227                                 break;
 228                 }
 229                 if (!list)
 230                         list = recv_add_gid(gid, NULL);
 231                 last = list;
 232         }
 233
 234         if (flags_ptr && list->flags & FLAG_SKIP_GROUP)
 235                 *flags_ptr |= FLAG_SKIP_GROUP;
 236         return list->id2;
 237 }
 238
 239 /* Add a uid to the list of uids.  Only called on sending side. */
 240 const char *add_uid(uid_t uid)
 241 {
 242         struct idlist *list;
 243         struct idlist *node;
 244
 245         if (uid == 0)   /* don't map root */
 246                 return NULL;
 247
 248         for (list = uidlist; list; list = list->next) {
 249                 if (list->id == uid)
 250                         return NULL;
 251         }
 252
 253         node = add_to_list(&uidlist, uid, uid_to_name(uid), 0, 0);
 254         return node->name;
 255 }
 256
 257 /* Add a gid to the list of gids.  Only called on sending side. */
 258 const char *add_gid(gid_t gid)
 259 {
 260         struct idlist *list;
 261         struct idlist *node;
 262
 263         if (gid == 0)   /* don't map root */
 264                 return NULL;
 265
 266         for (list = gidlist; list; list = list->next) {
 267                 if (list->id == gid)
 268                         return NULL;
 269         }
 270
 271         node = add_to_list(&gidlist, gid, gid_to_name(gid), 0, 0);
 272         return node->name;
 273 }
 274
 275 /* send a complete uid/gid mapping to the peer */
 276 void send_id_list(int f)
 277 {
 278         struct idlist *list;
 279
 280         if (preserve_uid || preserve_acls) {
 281                 int len;
 282                 /* we send sequences of uid/byte-length/name */
 283                 for (list = uidlist; list; list = list->next) {
 284                         if (!list->name)
 285                                 continue;
 286                         len = strlen(list->name);
 287                         write_varint30(f, list->id);
 288                         write_byte(f, len);
 289                         write_buf(f, list->name, len);
 290                 }
 291
 292                 /* terminate the uid list with a 0 uid. We explicitly exclude
 293                  * 0 from the list */
 294                 write_varint30(f, 0);
 295         }
 296
 297         if (preserve_gid || preserve_acls) {
 298                 int len;
 299                 for (list = gidlist; list; list = list->next) {
 300                         if (!list->name)
 301                                 continue;
 302                         len = strlen(list->name);
 303                         write_varint30(f, list->id);
 304                         write_byte(f, len);
 305                         write_buf(f, list->name, len);
 306                 }
 307                 write_varint30(f, 0);
 308         }
 309 }
 310
 311 uid_t recv_user_name(int f, uid_t uid)
 312 {
 313         struct idlist *node;
 314         int len = read_byte(f);
 315         char *name = new_array(char, len+1);
 316         if (!name)
 317                 out_of_memory("recv_user_name");
 318         read_sbuf(f, name, len);
 319         if (numeric_ids < 0) {
 320                 free(name);
 321                 name = NULL;
 322         }
 323         node = recv_add_uid(uid, name); /* node keeps name's memory */
 324         return node->id2;
 325 }
 326
 327 gid_t recv_group_name(int f, gid_t gid, uint16 *flags_ptr)
 328 {
 329         struct idlist *node;
 330         int len = read_byte(f);
 331         char *name = new_array(char, len+1);
 332         if (!name)
 333                 out_of_memory("recv_group_name");
 334         read_sbuf(f, name, len);
 335         if (numeric_ids < 0) {
 336                 free(name);
 337                 name = NULL;
 338         }
 339         node = recv_add_gid(gid, name); /* node keeps name's memory */
 340         if (flags_ptr && node->flags & FLAG_SKIP_GROUP)
 341                 *flags_ptr |= FLAG_SKIP_GROUP;
 342         return node->id2;
 343 }
 344
 345 /* recv a complete uid/gid mapping from the peer and map the uid/gid
 346  * in the file list to local names */
 347 void recv_id_list(int f, struct file_list *flist)
 348 {
 349         id_t id;
 350         int i;
 351
 352         if ((preserve_uid || preserve_acls) && numeric_ids <= 0) {
 353                 /* read the uid list */
 354                 while ((id = read_varint30(f)) != 0)
 355                         recv_user_name(f, id);
 356         }
 357
 358         if ((preserve_gid || preserve_acls) && numeric_ids <= 0) {
 359                 /* read the gid list */
 360                 while ((id = read_varint30(f)) != 0)
 361                         recv_group_name(f, id, NULL);
 362         }
 363
 364         /* Now convert all the uids/gids from sender values to our values. */
 365 #ifdef SUPPORT_ACLS
 366         if (preserve_acls && !numeric_ids)
 367                 match_acl_ids();
 368 #endif
 369         if (am_root && preserve_uid && !numeric_ids) {
 370                 for (i = 0; i < flist->used; i++)
 371                         F_OWNER(flist->files[i]) = match_uid(F_OWNER(flist->files[i]));
 372         }
 373         if (preserve_gid && (!am_root || !numeric_ids)) {
 374                 for (i = 0; i < flist->used; i++) {
 375                         F_GROUP(flist->files[i]) = match_gid(F_GROUP(flist->files[i]),
 376                                                              &flist->files[i]->flags);
 377                 }
 378         }
 379 }