ubusd_acl.c

   1 /*
   2  * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
   3  * Copyright (C) 2018 Hans Dedecker <dedeckeh@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #define _GNU_SOURCE
  16 #include <sys/socket.h>
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19
  20 #include <syslog.h>
  21 #include <unistd.h>
  22 #include <glob.h>
  23 #include <grp.h>
  24 #include <pwd.h>
  25
  26 #include <libubox/vlist.h>
  27 #include <libubox/blobmsg_json.h>
  28 #include <libubox/avl-cmp.h>
  29
  30 #include "ubusd.h"
  31
  32 #ifndef SO_PEERCRED
  33 struct ucred {
  34         int pid;
  35         int uid;
  36         int gid;
  37 };
  38 #endif
  39
  40 struct ubusd_acl_obj {
  41         struct avl_node avl;
  42         struct list_head list;
  43
  44         bool partial;
  45
  46         const char *user;
  47         const char *group;
  48
  49         struct blob_attr *methods;
  50         struct blob_attr *tags;
  51         struct blob_attr *priv;
  52         bool subscribe;
  53         bool publish;
  54         bool listen;
  55         bool send;
  56 };
  57
  58 struct ubusd_acl_file {
  59         struct vlist_node avl;
  60
  61         const char *user;
  62         const char *group;
  63
  64         struct blob_attr *blob;
  65         struct list_head acl;
  66
  67         int ok;
  68 };
  69
  70 const char *ubusd_acl_dir = "/usr/share/acl.d";
  71 static struct blob_buf bbuf;
  72 static struct avl_tree ubusd_acls;
  73 static int ubusd_acl_seq;
  74 static struct ubus_object *acl_obj;
  75
  76 static int
  77 ubusd_acl_match_cred(struct ubus_client *cl, struct ubusd_acl_obj *obj)
  78 {
  79         if (obj->user && !strcmp(cl->user, obj->user))
  80                 return 0;
  81
  82         if (obj->group && !strcmp(cl->group, obj->group))
  83                 return 0;
  84
  85         return -1;
  86 }
  87
  88 int
  89 ubusd_acl_check(struct ubus_client *cl, const char *obj,
  90                 const char *method, enum ubusd_acl_type type)
  91 {
  92         struct ubusd_acl_obj *acl;
  93         int match_len = 0;
  94
  95         if (!cl || !cl->uid || !obj)
  96                 return 0;
  97
  98         /*
  99          * Since this tree is sorted alphabetically, we can only expect
 100          * to find matching entries as long as the number of matching
 101          * characters between the access list string and the object path
 102          * is monotonically increasing.
 103          */
 104         avl_for_each_element(&ubusd_acls, acl, avl) {
 105                 const char *key = acl->avl.key;
 106                 int cur_match_len;
 107                 bool full_match;
 108
 109                 full_match = ubus_strmatch_len(obj, key, &cur_match_len);
 110                 if (cur_match_len < match_len)
 111                         break;
 112
 113                 match_len = cur_match_len;
 114
 115                 if (!full_match) {
 116                         if (!acl->partial)
 117                                 continue;
 118
 119                         if (match_len != (int) strlen(key))
 120                                 continue;
 121                 }
 122
 123                 if (ubusd_acl_match_cred(cl, acl))
 124                         continue;
 125
 126                 switch (type) {
 127                 case UBUS_ACL_PUBLISH:
 128                         if (acl->publish)
 129                                 return 0;
 130                         break;
 131
 132                 case UBUS_ACL_SUBSCRIBE:
 133                         if (acl->subscribe)
 134                                 return 0;
 135                         break;
 136
 137                 case UBUS_ACL_LISTEN:
 138                         if (acl->listen)
 139                                 return 0;
 140                         break;
 141
 142                 case UBUS_ACL_SEND:
 143                         if (acl->send)
 144                                 return 0;
 145                         break;
 146
 147                 case UBUS_ACL_ACCESS:
 148                         if (acl->methods) {
 149                                 struct blob_attr *cur;
 150                                 size_t rem;
 151
 152                                 blobmsg_for_each_attr(cur, acl->methods, rem)
 153                                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 154                                                 if (!strcmp(method, blobmsg_get_string(cur)))
 155                                                         return 0;
 156                         }
 157                         break;
 158                 }
 159         }
 160
 161         return -1;
 162 }
 163
 164 int
 165 ubusd_acl_init_client(struct ubus_client *cl, int fd)
 166 {
 167         struct ucred cred;
 168         struct passwd *pwd;
 169         struct group *group;
 170
 171 #ifdef SO_PEERCRED
 172         unsigned int len = sizeof(struct ucred);
 173
 174         if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) == -1)
 175                 return -1;
 176 #else
 177         memset(&cred, 0, sizeof(cred));
 178 #endif
 179
 180         pwd = getpwuid(cred.uid);
 181         if (!pwd)
 182                 return -1;
 183
 184         group = getgrgid(cred.gid);
 185         if (!group)
 186                 return -1;
 187
 188         cl->uid = cred.uid;
 189         cl->gid = cred.gid;
 190
 191         cl->group = strdup(group->gr_name);
 192         cl->user = strdup(pwd->pw_name);
 193
 194         return 0;
 195 }
 196
 197 void
 198 ubusd_acl_free_client(struct ubus_client *cl)
 199 {
 200         free(cl->group);
 201         free(cl->user);
 202 }
 203
 204 static void
 205 ubusd_acl_file_free(struct ubusd_acl_file *file)
 206 {
 207         struct ubusd_acl_obj *p, *q;
 208
 209         list_for_each_entry_safe(p, q, &file->acl, list) {
 210                 avl_delete(&ubusd_acls, &p->avl);
 211                 list_del(&p->list);
 212                 free(p);
 213         }
 214
 215         free(file);
 216 }
 217
 218 enum {
 219         ACL_ACCESS_METHODS,
 220         ACL_ACCESS_TAGS,
 221         ACL_ACCESS_PRIV,
 222         __ACL_ACCESS_MAX
 223 };
 224
 225 static const struct blobmsg_policy acl_obj_policy[__ACL_ACCESS_MAX] = {
 226         [ACL_ACCESS_METHODS] = { .name = "methods", .type = BLOBMSG_TYPE_ARRAY },
 227         [ACL_ACCESS_TAGS] = { .name = "tags", .type = BLOBMSG_TYPE_ARRAY },
 228         [ACL_ACCESS_PRIV] = { .name = "acl", .type = BLOBMSG_TYPE_TABLE },
 229 };
 230
 231 static struct ubusd_acl_obj*
 232 ubusd_acl_alloc_obj(struct ubusd_acl_file *file, const char *obj)
 233 {
 234         struct ubusd_acl_obj *o;
 235         int len = strlen(obj);
 236         char *k;
 237         bool partial = false;
 238
 239         if (obj[len - 1] == '*') {
 240                 partial = true;
 241                 len--;
 242         }
 243
 244         o = calloc_a(sizeof(*o), &k, len + 1);
 245         o->partial = partial;
 246         o->user = file->user;
 247         o->group = file->group;
 248         o->avl.key = memcpy(k, obj, len);
 249
 250         list_add(&o->list, &file->acl);
 251         avl_insert(&ubusd_acls, &o->avl);
 252
 253         return o;
 254 }
 255
 256 static void
 257 ubusd_acl_add_access(struct ubusd_acl_file *file, struct blob_attr *obj)
 258 {
 259         struct blob_attr *tb[__ACL_ACCESS_MAX];
 260         struct ubusd_acl_obj *o;
 261
 262         blobmsg_parse(acl_obj_policy, __ACL_ACCESS_MAX, tb, blobmsg_data(obj),
 263                       blobmsg_data_len(obj));
 264
 265         if (!tb[ACL_ACCESS_METHODS] && !tb[ACL_ACCESS_TAGS] && !tb[ACL_ACCESS_PRIV])
 266                 return;
 267
 268         o = ubusd_acl_alloc_obj(file, blobmsg_name(obj));
 269
 270         o->methods = tb[ACL_ACCESS_METHODS];
 271         o->tags = tb[ACL_ACCESS_TAGS];
 272         o->priv = tb[ACL_ACCESS_PRIV];
 273
 274         if (file->user || file->group)
 275                 file->ok = 1;
 276 }
 277
 278 static void
 279 ubusd_acl_add_subscribe(struct ubusd_acl_file *file, const char *obj)
 280 {
 281         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 282
 283         o->subscribe = true;
 284 }
 285
 286 static void
 287 ubusd_acl_add_publish(struct ubusd_acl_file *file, const char *obj)
 288 {
 289         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 290
 291         o->publish = true;
 292 }
 293
 294 static void ubusd_acl_add_listen(struct ubusd_acl_file *file, const char *obj)
 295 {
 296         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 297
 298         o->listen = true;
 299 }
 300
 301 static void ubusd_acl_add_send(struct ubusd_acl_file *file, const char *obj)
 302 {
 303         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 304
 305         o->send = true;
 306 }
 307
 308 enum {
 309         ACL_USER,
 310         ACL_GROUP,
 311         ACL_ACCESS,
 312         ACL_PUBLISH,
 313         ACL_SUBSCRIBE,
 314         ACL_INHERIT,
 315         ACL_LISTEN,
 316         ACL_SEND,
 317         __ACL_MAX
 318 };
 319
 320 static const struct blobmsg_policy acl_policy[__ACL_MAX] = {
 321         [ACL_USER] = { .name = "user", .type = BLOBMSG_TYPE_STRING },
 322         [ACL_GROUP] = { .name = "group", .type = BLOBMSG_TYPE_STRING },
 323         [ACL_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_TABLE },
 324         [ACL_PUBLISH] = { .name = "publish", .type = BLOBMSG_TYPE_ARRAY },
 325         [ACL_SUBSCRIBE] = { .name = "subscribe", .type = BLOBMSG_TYPE_ARRAY },
 326         [ACL_INHERIT] = { .name = "inherit", .type = BLOBMSG_TYPE_ARRAY },
 327         [ACL_LISTEN] = { .name= "listen", .type = BLOBMSG_TYPE_ARRAY },
 328         [ACL_SEND] = { .name= "send", .type = BLOBMSG_TYPE_ARRAY },
 329 };
 330
 331 static void
 332 ubusd_acl_file_add(struct ubusd_acl_file *file)
 333 {
 334         struct blob_attr *tb[__ACL_MAX], *cur;
 335         size_t rem;
 336
 337         blobmsg_parse(acl_policy, __ACL_MAX, tb, blob_data(file->blob),
 338                       blob_len(file->blob));
 339
 340         if (tb[ACL_USER])
 341                 file->user = blobmsg_get_string(tb[ACL_USER]);
 342         else if (tb[ACL_GROUP])
 343                 file->group = blobmsg_get_string(tb[ACL_GROUP]);
 344         else
 345                 return;
 346
 347         if (tb[ACL_ACCESS])
 348                 blobmsg_for_each_attr(cur, tb[ACL_ACCESS], rem)
 349                         ubusd_acl_add_access(file, cur);
 350
 351         if (tb[ACL_SUBSCRIBE])
 352                 blobmsg_for_each_attr(cur, tb[ACL_SUBSCRIBE], rem)
 353                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 354                                 ubusd_acl_add_subscribe(file, blobmsg_get_string(cur));
 355
 356         if (tb[ACL_PUBLISH])
 357                 blobmsg_for_each_attr(cur, tb[ACL_PUBLISH], rem)
 358                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 359                                 ubusd_acl_add_publish(file, blobmsg_get_string(cur));
 360
 361         if (tb[ACL_LISTEN])
 362                 blobmsg_for_each_attr(cur, tb[ACL_LISTEN], rem)
 363                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 364                                 ubusd_acl_add_listen(file, blobmsg_get_string(cur));
 365
 366         if (tb[ACL_SEND])
 367                 blobmsg_for_each_attr(cur, tb[ACL_SEND], rem)
 368                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 369                                 ubusd_acl_add_send(file, blobmsg_get_string(cur));
 370 }
 371
 372 static void
 373 ubusd_acl_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 374         struct vlist_node *node_old)
 375 {
 376         struct ubusd_acl_file *file;
 377
 378         if (node_old) {
 379                 file = container_of(node_old, struct ubusd_acl_file, avl);
 380                 ubusd_acl_file_free(file);
 381         }
 382
 383         if (node_new) {
 384                 file = container_of(node_new, struct ubusd_acl_file, avl);
 385                 ubusd_acl_file_add(file);
 386         }
 387 }
 388
 389 static struct ubus_msg_buf *
 390 ubusd_create_sequence_event_msg(void *priv, const char *id)
 391 {
 392         void *s;
 393
 394         blob_buf_init(&b, 0);
 395         blob_put_int32(&b, UBUS_ATTR_OBJID, 0);
 396         blob_put_string(&b, UBUS_ATTR_METHOD, id);
 397         s = blob_nest_start(&b, UBUS_ATTR_DATA);
 398         blobmsg_add_u32(&b, "sequence", ubusd_acl_seq);
 399         blob_nest_end(&b, s);
 400
 401         return ubus_msg_new(b.head, blob_raw_len(b.head), true);
 402 }
 403
 404 static VLIST_TREE(ubusd_acl_files, avl_strcmp, ubusd_acl_update_cb, false, false);
 405
 406 static int
 407 ubusd_acl_load_file(const char *filename)
 408 {
 409         struct ubusd_acl_file *file;
 410         void *blob;
 411
 412         blob_buf_init(&bbuf, 0);
 413         if (!blobmsg_add_json_from_file(&bbuf, filename)) {
 414                 syslog(LOG_ERR, "failed to parse %s\n", filename);
 415                 return -1;
 416         }
 417
 418         file = calloc_a(sizeof(*file), &blob, blob_raw_len(bbuf.head));
 419         if (!file)
 420                 return -1;
 421
 422         file->blob = blob;
 423
 424         memcpy(blob, bbuf.head, blob_raw_len(bbuf.head));
 425         INIT_LIST_HEAD(&file->acl);
 426
 427         vlist_add(&ubusd_acl_files, &file->avl, filename);
 428         syslog(LOG_INFO, "loading %s\n", filename);
 429
 430         return 0;
 431 }
 432
 433 void
 434 ubusd_acl_load(void)
 435 {
 436         struct stat st;
 437         glob_t gl;
 438         size_t j;
 439         const char *suffix = "/*.json";
 440         char *path = alloca(strlen(ubusd_acl_dir) + strlen(suffix) + 1);
 441
 442         sprintf(path, "%s%s", ubusd_acl_dir, suffix);
 443         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 444                 return;
 445
 446         vlist_update(&ubusd_acl_files);
 447         for (j = 0; j < gl.gl_pathc; j++) {
 448                 if (stat(gl.gl_pathv[j], &st) || !S_ISREG(st.st_mode))
 449                         continue;
 450
 451                 if (st.st_uid || st.st_gid) {
 452                         syslog(LOG_ERR, "%s has wrong owner\n", gl.gl_pathv[j]);
 453                         continue;
 454                 }
 455                 if (st.st_mode & (S_IWOTH | S_IWGRP | S_IXOTH)) {
 456                         syslog(LOG_ERR, "%s has wrong permissions\n", gl.gl_pathv[j]);
 457                         continue;
 458                 }
 459                 ubusd_acl_load_file(gl.gl_pathv[j]);
 460         }
 461
 462         globfree(&gl);
 463         vlist_flush(&ubusd_acl_files);
 464         ubusd_acl_seq++;
 465         ubusd_send_event(NULL, "ubus.acl.sequence", ubusd_create_sequence_event_msg, NULL);
 466 }
 467
 468 static void
 469 ubusd_reply_add(struct ubus_object *obj)
 470 {
 471         struct ubusd_acl_obj *acl;
 472         int match_len = 0;
 473
 474         if (!obj->path.key)
 475                 return;
 476
 477         /*
 478          * Since this tree is sorted alphabetically, we can only expect
 479          * to find matching entries as long as the number of matching
 480          * characters between the access list string and the object path
 481          * is monotonically increasing.
 482          */
 483         avl_for_each_element(&ubusd_acls, acl, avl) {
 484                 const char *key = acl->avl.key;
 485                 int cur_match_len;
 486                 bool full_match;
 487                 void *c;
 488
 489                 if (!acl->priv)
 490                         continue;
 491
 492                 full_match = ubus_strmatch_len(obj->path.key, key, &cur_match_len);
 493                 if (cur_match_len < match_len)
 494                         break;
 495
 496                 match_len = cur_match_len;
 497
 498                 if (!full_match) {
 499                         if (!acl->partial)
 500                                 continue;
 501
 502                         if (match_len != (int) strlen(key))
 503                                 continue;
 504                 }
 505
 506                 c = blobmsg_open_table(&b, NULL);
 507                 blobmsg_add_string(&b, "obj", obj->path.key);
 508                 if (acl->user)
 509                         blobmsg_add_string(&b, "user", acl->user);
 510                 if (acl->group)
 511                         blobmsg_add_string(&b, "group", acl->group);
 512
 513                 blobmsg_add_field(&b, blobmsg_type(acl->priv), "acl",
 514                         blobmsg_data(acl->priv), blobmsg_data_len(acl->priv));
 515
 516                 blobmsg_close_table(&b, c);
 517         }
 518 }
 519
 520 static int ubusd_reply_query(struct ubus_client *cl, struct ubus_msg_buf *ub, struct blob_attr **attr, struct blob_attr *msg)
 521 {
 522         struct ubus_object *obj;
 523         void *d, *a;
 524
 525         if (!attr[UBUS_ATTR_OBJID])
 526                 return UBUS_STATUS_INVALID_ARGUMENT;
 527
 528         obj = ubusd_find_object(blob_get_u32(attr[UBUS_ATTR_OBJID]));
 529         if (!obj)
 530                 return UBUS_STATUS_NOT_FOUND;
 531
 532         blob_buf_init(&b, 0);
 533         blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id.id);
 534         d = blob_nest_start(&b, UBUS_ATTR_DATA);
 535
 536         blobmsg_add_u32(&b, "seq", ubusd_acl_seq);
 537         a = blobmsg_open_array(&b, "acl");
 538         list_for_each_entry(obj, &cl->objects, list)
 539                 ubusd_reply_add(obj);
 540         blobmsg_close_table(&b, a);
 541
 542         blob_nest_end(&b, d);
 543
 544         ubus_proto_send_msg_from_blob(cl, ub, UBUS_MSG_DATA);
 545
 546         return 0;
 547 }
 548
 549 static int ubusd_acl_recv(struct ubus_client *cl, struct ubus_msg_buf *ub, const char *method, struct blob_attr *msg)
 550 {
 551         if (!strcmp(method, "query"))
 552                 return ubusd_reply_query(cl, ub, ubus_parse_msg(ub->data, blob_raw_len(ub->data)), msg);
 553
 554         return UBUS_STATUS_INVALID_COMMAND;
 555 }
 556
 557 void ubusd_acl_init(void)
 558 {
 559         ubus_init_string_tree(&ubusd_acls, true);
 560         acl_obj = ubusd_create_object_internal(NULL, UBUS_SYSTEM_OBJECT_ACL);
 561         acl_obj->recv_msg = ubusd_acl_recv;
 562 }