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) 2004-2009 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 struct idlist {
  43         struct idlist *next;
  44         const char *name;
  45         id_t id, id2;
  46         uint16 flags;
  47 };
  48
  49 static struct idlist *uidlist;
  50 static struct idlist *gidlist;
  51
  52 static struct idlist *add_to_list(struct idlist **root, id_t id, const char *name,
  53                                   id_t id2, uint16 flags)
  54 {
  55         struct idlist *node = new(struct idlist);
  56         if (!node)
  57                 out_of_memory("add_to_list");
  58         node->next = *root;
  59         node->name = name;
  60         node->id = id;
  61         node->id2 = id2;
  62         node->flags = flags;
  63         *root = node;
  64         return node;
  65 }
  66
  67 /* turn a uid into a user name */
  68 static const char *uid_to_name(uid_t uid)
  69 {
  70         struct passwd *pass = getpwuid(uid);
  71         if (pass)
  72                 return strdup(pass->pw_name);
  73         return NULL;
  74 }
  75
  76 /* turn a gid into a group name */
  77 static const char *gid_to_name(gid_t gid)
  78 {
  79         struct group *grp = getgrgid(gid);
  80         if (grp)
  81                 return strdup(grp->gr_name);
  82         return NULL;
  83 }
  84
  85 static uid_t map_uid(uid_t id, const char *name)
  86 {
  87         uid_t uid;
  88         if (id != 0 && name_to_uid(name, &uid))
  89                 return uid;
  90         return id;
  91 }
  92
  93 static gid_t map_gid(gid_t id, const char *name)
  94 {
  95         gid_t gid;
  96         if (id != 0 && name_to_gid(name, &gid))
  97                 return gid;
  98         return id;
  99 }
 100
 101 static int is_in_group(gid_t gid)
 102 {
 103 #ifdef HAVE_GETGROUPS
 104         static gid_t last_in;
 105         static int ngroups = -2, last_out = -1;
 106         static GETGROUPS_T *gidset;
 107         int n;
 108
 109         if (gid == last_in && last_out >= 0)
 110                 return last_out;
 111         if (ngroups < -1) {
 112                 gid_t mygid = MY_GID();
 113                 if ((ngroups = getgroups(0, NULL)) < 0)
 114                         ngroups = 0;
 115                 gidset = new_array(GETGROUPS_T, ngroups+1);
 116                 if (!gidset)
 117                         out_of_memory("is_in_group");
 118                 if (ngroups > 0)
 119                         ngroups = getgroups(ngroups, gidset);
 120                 /* The default gid might not be in the list on some systems. */
 121                 for (n = 0; n < ngroups; n++) {
 122                         if (gidset[n] == mygid)
 123                                 break;
 124                 }
 125                 if (n == ngroups)
 126                         gidset[ngroups++] = mygid;
 127                 if (verbose > 3) {
 128                         int pos;
 129                         char *gidbuf = new_array(char, ngroups*21+32);
 130                         if (!gidbuf)
 131                                 out_of_memory("is_in_group");
 132                         pos = snprintf(gidbuf, 32, "process has %d gid%s: ",
 133                                        ngroups, ngroups == 1? "" : "s");
 134                         for (n = 0; n < ngroups; n++) {
 135                                 pos += snprintf(gidbuf+pos, 21, " %d", (int)gidset[n]);
 136                         }
 137                         rprintf(FINFO, "%s\n", gidbuf);
 138                         free(gidbuf);
 139                 }
 140         }
 141
 142         last_in = gid;
 143         for (n = 0; n < ngroups; n++) {
 144                 if (gidset[n] == gid)
 145                         return last_out = 1;
 146         }
 147         return last_out = 0;
 148
 149 #else
 150         static gid_t mygid = GID_NONE;
 151         if (mygid == GID_NONE) {
 152                 mygid = MY_GID();
 153                 if (verbose > 3)
 154                         rprintf(FINFO, "process has gid %u\n", (unsigned)mygid);
 155         }
 156         return gid == mygid;
 157 #endif
 158 }
 159
 160 /* Add a uid to the list of uids.  Only called on receiving side. */
 161 static struct idlist *recv_add_uid(uid_t id, const char *name)
 162 {
 163         uid_t id2 = name ? map_uid(id, name) : id;
 164         struct idlist *node;
 165
 166         node = add_to_list(&uidlist, id, name, id2, 0);
 167
 168         if (verbose > 3) {
 169                 rprintf(FINFO, "uid %u(%s) maps to %u\n",
 170                         (unsigned)id, name ? name : "", (unsigned)id2);
 171         }
 172
 173         return node;
 174 }
 175
 176 /* Add a gid to the list of gids.  Only called on receiving side. */
 177 static struct idlist *recv_add_gid(gid_t id, const char *name)
 178 {
 179         gid_t id2 = name ? map_gid(id, name) : id;
 180         struct idlist *node;
 181
 182         node = add_to_list(&gidlist, id, name, id2,
 183                 !am_root && !is_in_group(id2) ? FLAG_SKIP_GROUP : 0);
 184
 185         if (verbose > 3) {
 186                 rprintf(FINFO, "gid %u(%s) maps to %u\n",
 187                         (unsigned)id, name ? name : "", (unsigned)id2);
 188         }
 189
 190         return node;
 191 }
 192
 193 /* this function is a definate candidate for a faster algorithm */
 194 uid_t match_uid(uid_t uid)
 195 {
 196         static uid_t last_in, last_out;
 197         struct idlist *list;
 198
 199         if (uid == 0)
 200                 return 0;
 201
 202         if (uid == last_in)
 203                 return last_out;
 204
 205         last_in = uid;
 206
 207         for (list = uidlist; list; list = list->next) {
 208                 if (list->id == uid)
 209                         return last_out = list->id2;
 210         }
 211
 212         return last_out = uid;
 213 }
 214
 215 gid_t match_gid(gid_t gid, uint16 *flags_ptr)
 216 {
 217         static struct idlist *last = NULL;
 218         struct idlist *list;
 219
 220         if (last && gid == last->id)
 221                 list = last;
 222         else {
 223                 for (list = gidlist; list; list = list->next) {
 224                         if (list->id == gid)
 225                                 break;
 226                 }
 227                 if (!list)
 228                         list = recv_add_gid(gid, NULL);
 229                 last = list;
 230         }
 231
 232         if (flags_ptr && list->flags & FLAG_SKIP_GROUP)
 233                 *flags_ptr |= FLAG_SKIP_GROUP;
 234         return list->id2;
 235 }
 236
 237 /* Add a uid to the list of uids.  Only called on sending side. */
 238 const char *add_uid(uid_t uid)
 239 {
 240         struct idlist *list;
 241         struct idlist *node;
 242
 243         if (uid == 0)   /* don't map root */
 244                 return NULL;
 245
 246         for (list = uidlist; list; list = list->next) {
 247                 if (list->id == uid)
 248                         return NULL;
 249         }
 250
 251         node = add_to_list(&uidlist, uid, uid_to_name(uid), 0, 0);
 252         return node->name;
 253 }
 254
 255 /* Add a gid to the list of gids.  Only called on sending side. */
 256 const char *add_gid(gid_t gid)
 257 {
 258         struct idlist *list;
 259         struct idlist *node;
 260
 261         if (gid == 0)   /* don't map root */
 262                 return NULL;
 263
 264         for (list = gidlist; list; list = list->next) {
 265                 if (list->id == gid)
 266                         return NULL;
 267         }
 268
 269         node = add_to_list(&gidlist, gid, gid_to_name(gid), 0, 0);
 270         return node->name;
 271 }
 272
 273 /* send a complete uid/gid mapping to the peer */
 274 void send_id_list(int f)
 275 {
 276         struct idlist *list;
 277
 278         if (preserve_uid || preserve_acls) {
 279                 int len;
 280                 /* we send sequences of uid/byte-length/name */
 281                 for (list = uidlist; list; list = list->next) {
 282                         if (!list->name)
 283                                 continue;
 284                         len = strlen(list->name);
 285                         write_varint30(f, list->id);
 286                         write_byte(f, len);
 287                         write_buf(f, list->name, len);
 288                 }
 289
 290                 /* terminate the uid list with a 0 uid. We explicitly exclude
 291                  * 0 from the list */
 292                 write_varint30(f, 0);
 293         }
 294
 295         if (preserve_gid || preserve_acls) {
 296                 int len;
 297                 for (list = gidlist; list; list = list->next) {
 298                         if (!list->name)
 299                                 continue;
 300                         len = strlen(list->name);
 301                         write_varint30(f, list->id);
 302                         write_byte(f, len);
 303                         write_buf(f, list->name, len);
 304                 }
 305                 write_varint30(f, 0);
 306         }
 307 }
 308
 309 uid_t recv_user_name(int f, uid_t uid)
 310 {
 311         struct idlist *node;
 312         int len = read_byte(f);
 313         char *name = new_array(char, len+1);
 314         if (!name)
 315                 out_of_memory("recv_user_name");
 316         read_sbuf(f, name, len);
 317         if (numeric_ids < 0) {
 318                 free(name);
 319                 name = NULL;
 320         }
 321         node = recv_add_uid(uid, name); /* node keeps name's memory */
 322         return node->id2;
 323 }
 324
 325 gid_t recv_group_name(int f, gid_t gid, uint16 *flags_ptr)
 326 {
 327         struct idlist *node;
 328         int len = read_byte(f);
 329         char *name = new_array(char, len+1);
 330         if (!name)
 331                 out_of_memory("recv_group_name");
 332         read_sbuf(f, name, len);
 333         if (numeric_ids < 0) {
 334                 free(name);
 335                 name = NULL;
 336         }
 337         node = recv_add_gid(gid, name); /* node keeps name's memory */
 338         if (flags_ptr && node->flags & FLAG_SKIP_GROUP)
 339                 *flags_ptr |= FLAG_SKIP_GROUP;
 340         return node->id2;
 341 }
 342
 343 /* recv a complete uid/gid mapping from the peer and map the uid/gid
 344  * in the file list to local names */
 345 void recv_id_list(int f, struct file_list *flist)
 346 {
 347         id_t id;
 348         int i;
 349
 350         if ((preserve_uid || preserve_acls) && numeric_ids <= 0) {
 351                 /* read the uid list */
 352                 while ((id = read_varint30(f)) != 0)
 353                         recv_user_name(f, id);
 354         }
 355
 356         if ((preserve_gid || preserve_acls) && numeric_ids <= 0) {
 357                 /* read the gid list */
 358                 while ((id = read_varint30(f)) != 0)
 359                         recv_group_name(f, id, NULL);
 360         }
 361
 362         /* Now convert all the uids/gids from sender values to our values. */
 363 #ifdef SUPPORT_ACLS
 364         if (preserve_acls && !numeric_ids)
 365                 match_acl_ids();
 366 #endif
 367         if (am_root && preserve_uid && !numeric_ids) {
 368                 for (i = 0; i < flist->used; i++)
 369                         F_OWNER(flist->files[i]) = match_uid(F_OWNER(flist->files[i]));
 370         }
 371         if (preserve_gid && (!am_root || !numeric_ids)) {
 372                 for (i = 0; i < flist->used; i++) {
 373                         F_GROUP(flist->files[i]) = match_gid(F_GROUP(flist->files[i]),
 374                                                              &flist->files[i]->flags);
 375                 }
 376         }
 377 }