ubusd_acl.c

   1 /*
   2  * Copyright (C) 2015 John Crispin <blogic@openwrt.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License version 2.1
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define _GNU_SOURCE
  15 #include <sys/socket.h>
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18
  19 #include <syslog.h>
  20 #include <unistd.h>
  21 #include <glob.h>
  22 #include <grp.h>
  23 #include <pwd.h>
  24
  25 #include <libubox/vlist.h>
  26 #include <libubox/blobmsg_json.h>
  27 #include <libubox/avl-cmp.h>
  28
  29 #include "ubusd.h"
  30
  31 #ifndef SO_PEERCRED
  32 struct ucred {
  33         int pid;
  34         int uid;
  35         int gid;
  36 };
  37 #endif
  38
  39 struct ubusd_acl_obj {
  40         struct avl_node avl;
  41         struct list_head list;
  42
  43         const char *user;
  44         const char *group;
  45
  46         struct blob_attr *methods;
  47         struct blob_attr *tags;
  48         struct blob_attr *priv;
  49         bool subscribe;
  50         bool publish;
  51 };
  52
  53 struct ubusd_acl_file {
  54         struct vlist_node avl;
  55
  56         const char *user;
  57         const char *group;
  58
  59         struct blob_attr *blob;
  60         struct list_head acl;
  61
  62         int ok;
  63 };
  64
  65 const char *ubusd_acl_dir = "/usr/share/acl.d";
  66 static struct blob_buf bbuf;
  67 static struct avl_tree ubusd_acls;
  68 static int ubusd_acl_seq;
  69 static struct ubus_object *acl_obj;
  70
  71 static int
  72 ubusd_acl_match_path(const void *k1, const void *k2, void *ptr)
  73 {
  74         const char *name = k1;
  75         const char *match = k2;
  76         char *wildcard = strstr(match, "\t");
  77
  78         if (wildcard)
  79                 return strncmp(name, match, wildcard - match);
  80
  81         return strcmp(name, match);
  82 }
  83
  84 static int
  85 ubusd_acl_match_cred(struct ubus_client *cl, struct ubusd_acl_obj *obj)
  86 {
  87         if (obj->user && !strcmp(cl->user, obj->user))
  88                 return 0;
  89
  90         if (obj->group && !strcmp(cl->group, obj->group))
  91                 return 0;
  92
  93         return -1;
  94 }
  95
  96 int
  97 ubusd_acl_check(struct ubus_client *cl, const char *obj,
  98                 const char *method, enum ubusd_acl_type type)
  99 {
 100         struct ubusd_acl_obj *acl;
 101         struct blob_attr *cur;
 102         int rem;
 103
 104         if (!cl->gid && !cl->uid)
 105                 return 0;
 106
 107         acl = avl_find_ge_element(&ubusd_acls, obj, acl, avl);
 108         avl_for_element_to_last(&ubusd_acls, acl, acl, avl) {
 109                 int diff = ubusd_acl_match_path(obj, acl->avl.key, NULL);
 110
 111                 if (diff)
 112                         break;
 113
 114                 if (ubusd_acl_match_cred(cl, acl))
 115                         continue;
 116
 117                 switch (type) {
 118                 case UBUS_ACL_PUBLISH:
 119                         if (acl->publish)
 120                                 return 0;
 121                         break;
 122
 123                 case UBUS_ACL_SUBSCRIBE:
 124                         if (acl->subscribe)
 125                                 return 0;
 126                         break;
 127
 128                 case UBUS_ACL_ACCESS:
 129                         if (acl->methods)
 130                                 blobmsg_for_each_attr(cur, acl->methods, rem)
 131                                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 132                                                 if (!ubusd_acl_match_path(method, blobmsg_get_string(cur), NULL))
 133                                                         return 0;
 134                         break;
 135                 }
 136         }
 137
 138         return -1;
 139 }
 140
 141 int
 142 ubusd_acl_init_client(struct ubus_client *cl, int fd)
 143 {
 144         struct ucred cred;
 145         struct passwd *pwd;
 146         struct group *group;
 147
 148 #ifdef SO_PEERCRED
 149         unsigned int len = sizeof(struct ucred);
 150
 151         if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) == -1)
 152                 return -1;
 153 #else
 154         memset(&cred, 0, sizeof(cred));
 155 #endif
 156
 157         pwd = getpwuid(cred.uid);
 158         if (!pwd)
 159                 return -1;
 160
 161         group = getgrgid(cred.gid);
 162         if (!group)
 163                 return -1;
 164
 165         cl->uid = cred.uid;
 166         cl->gid = cred.gid;
 167
 168         cl->group = strdup(group->gr_name);
 169         cl->user = strdup(pwd->pw_name);
 170
 171         return 0;
 172 }
 173
 174 static void
 175 ubusd_acl_file_free(struct ubusd_acl_file *file)
 176 {
 177         struct ubusd_acl_obj *p, *q;
 178
 179         list_for_each_entry_safe(p, q, &file->acl, list) {
 180                 avl_delete(&ubusd_acls, &p->avl);
 181                 list_del(&p->list);
 182                 free(p);
 183         }
 184
 185         free(file);
 186 }
 187
 188 enum {
 189         ACL_ACCESS_METHODS,
 190         ACL_ACCESS_TAGS,
 191         ACL_ACCESS_PRIV,
 192         __ACL_ACCESS_MAX
 193 };
 194
 195 static const struct blobmsg_policy acl_obj_policy[__ACL_ACCESS_MAX] = {
 196         [ACL_ACCESS_METHODS] = { .name = "methods", .type = BLOBMSG_TYPE_ARRAY },
 197         [ACL_ACCESS_TAGS] = { .name = "tags", .type = BLOBMSG_TYPE_ARRAY },
 198         [ACL_ACCESS_PRIV] = { .name = "acl", .type = BLOBMSG_TYPE_TABLE },
 199 };
 200
 201 static struct ubusd_acl_obj*
 202 ubusd_acl_alloc_obj(struct ubusd_acl_file *file, const char *obj)
 203 {
 204         struct ubusd_acl_obj *o;
 205         char *k;
 206
 207         o = calloc_a(sizeof(*o), &k, strlen(obj) + 1);
 208         o->user = file->user;
 209         o->group = file->group;
 210         o->avl.key = k;
 211         strcpy(k, obj);
 212
 213         while (*k) {
 214                 if (*k == '*')
 215                         *k = '\t';
 216                 k++;
 217         }
 218
 219         list_add(&o->list, &file->acl);
 220         avl_insert(&ubusd_acls, &o->avl);
 221
 222         return o;
 223 }
 224
 225 static void
 226 ubusd_acl_add_access(struct ubusd_acl_file *file, struct blob_attr *obj)
 227 {
 228         struct blob_attr *tb[__ACL_ACCESS_MAX];
 229         struct ubusd_acl_obj *o;
 230
 231         blobmsg_parse(acl_obj_policy, __ACL_ACCESS_MAX, tb, blobmsg_data(obj),
 232                       blobmsg_data_len(obj));
 233
 234         if (!tb[ACL_ACCESS_METHODS] && !tb[ACL_ACCESS_TAGS] && !tb[ACL_ACCESS_PRIV])
 235                 return;
 236
 237         o = ubusd_acl_alloc_obj(file, blobmsg_name(obj));
 238
 239         o->methods = tb[ACL_ACCESS_METHODS];
 240         o->tags = tb[ACL_ACCESS_TAGS];
 241         o->priv = tb[ACL_ACCESS_PRIV];
 242
 243         if (file->user || file->group)
 244                 file->ok = 1;
 245 }
 246
 247 static void
 248 ubusd_acl_add_subscribe(struct ubusd_acl_file *file, const char *obj)
 249 {
 250         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 251
 252         o->subscribe = true;
 253 }
 254
 255 static void
 256 ubusd_acl_add_publish(struct ubusd_acl_file *file, const char *obj)
 257 {
 258         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 259
 260         o->publish = true;
 261 }
 262
 263 enum {
 264         ACL_USER,
 265         ACL_GROUP,
 266         ACL_ACCESS,
 267         ACL_PUBLISH,
 268         ACL_SUBSCRIBE,
 269         ACL_INHERIT,
 270         __ACL_MAX
 271 };
 272
 273 static const struct blobmsg_policy acl_policy[__ACL_MAX] = {
 274         [ACL_USER] = { .name = "user", .type = BLOBMSG_TYPE_STRING },
 275         [ACL_GROUP] = { .name = "group", .type = BLOBMSG_TYPE_STRING },
 276         [ACL_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_TABLE },
 277         [ACL_PUBLISH] = { .name = "publish", .type = BLOBMSG_TYPE_ARRAY },
 278         [ACL_SUBSCRIBE] = { .name = "subscribe", .type = BLOBMSG_TYPE_ARRAY },
 279         [ACL_INHERIT] = { .name = "inherit", .type = BLOBMSG_TYPE_ARRAY },
 280 };
 281
 282 static void
 283 ubusd_acl_file_add(struct ubusd_acl_file *file)
 284 {
 285         struct blob_attr *tb[__ACL_MAX], *cur;
 286         int rem;
 287
 288         blobmsg_parse(acl_policy, __ACL_MAX, tb, blob_data(file->blob),
 289                       blob_len(file->blob));
 290
 291         if (tb[ACL_USER])
 292                 file->user = blobmsg_get_string(tb[ACL_USER]);
 293         else if (tb[ACL_GROUP])
 294                 file->group = blobmsg_get_string(tb[ACL_GROUP]);
 295         else
 296                 return;
 297
 298         if (tb[ACL_ACCESS])
 299                 blobmsg_for_each_attr(cur, tb[ACL_ACCESS], rem)
 300                         ubusd_acl_add_access(file, cur);
 301
 302         if (tb[ACL_SUBSCRIBE])
 303                 blobmsg_for_each_attr(cur, tb[ACL_SUBSCRIBE], rem)
 304                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 305                                 ubusd_acl_add_subscribe(file, blobmsg_get_string(cur));
 306
 307         if (tb[ACL_PUBLISH])
 308                 blobmsg_for_each_attr(cur, tb[ACL_PUBLISH], rem)
 309                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 310                                 ubusd_acl_add_publish(file, blobmsg_get_string(cur));
 311 }
 312
 313 static void
 314 ubusd_acl_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 315         struct vlist_node *node_old)
 316 {
 317         struct ubusd_acl_file *file;
 318
 319         if (node_old) {
 320                 file = container_of(node_old, struct ubusd_acl_file, avl);
 321                 ubusd_acl_file_free(file);
 322         }
 323
 324         if (node_new) {
 325                 file = container_of(node_new, struct ubusd_acl_file, avl);
 326                 ubusd_acl_file_add(file);
 327         }
 328 }
 329
 330 static struct ubus_msg_buf *
 331 ubusd_create_sequence_event_msg(void *priv, const char *id)
 332 {
 333         void *s;
 334
 335         blob_buf_init(&b, 0);
 336         blob_put_int32(&b, UBUS_ATTR_OBJID, 0);
 337         blob_put_string(&b, UBUS_ATTR_METHOD, id);
 338         s = blob_nest_start(&b, UBUS_ATTR_DATA);
 339         blobmsg_add_u32(&b, "sequence", ubusd_acl_seq);
 340         blob_nest_end(&b, s);
 341
 342         return ubus_msg_new(b.head, blob_raw_len(b.head), true);
 343 }
 344
 345 static VLIST_TREE(ubusd_acl_files, avl_strcmp, ubusd_acl_update_cb, false, false);
 346
 347 static int
 348 ubusd_acl_load_file(const char *filename)
 349 {
 350         struct ubusd_acl_file *file;
 351         void *blob;
 352
 353         blob_buf_init(&bbuf, 0);
 354         if (!blobmsg_add_json_from_file(&bbuf, filename)) {
 355                 syslog(LOG_ERR, "failed to parse %s\n", filename);
 356                 return -1;
 357         }
 358
 359         file = calloc_a(sizeof(*file), &blob, blob_raw_len(bbuf.head));
 360         if (!file)
 361                 return -1;
 362
 363         file->blob = blob;
 364
 365         memcpy(blob, bbuf.head, blob_raw_len(bbuf.head));
 366         INIT_LIST_HEAD(&file->acl);
 367
 368         vlist_add(&ubusd_acl_files, &file->avl, filename);
 369         syslog(LOG_INFO, "loading %s\n", filename);
 370
 371         return 0;
 372 }
 373
 374 void
 375 ubusd_acl_load(void)
 376 {
 377         struct stat st;
 378         glob_t gl;
 379         int j;
 380         const char *suffix = "/*.json";
 381         char *path = alloca(strlen(ubusd_acl_dir) + strlen(suffix) + 1);
 382
 383         sprintf(path, "%s%s", ubusd_acl_dir, suffix);
 384         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 385                 return;
 386
 387         vlist_update(&ubusd_acl_files);
 388         for (j = 0; j < gl.gl_pathc; j++) {
 389                 if (stat(gl.gl_pathv[j], &st) || !S_ISREG(st.st_mode))
 390                         continue;
 391
 392                 if (st.st_uid || st.st_gid) {
 393                         syslog(LOG_ERR, "%s has wrong owner\n", gl.gl_pathv[j]);
 394                         continue;
 395                 }
 396                 if (st.st_mode & (S_IWOTH | S_IWGRP | S_IXOTH)) {
 397                         syslog(LOG_ERR, "%s has wrong permissions\n", gl.gl_pathv[j]);
 398                         continue;
 399                 }
 400                 ubusd_acl_load_file(gl.gl_pathv[j]);
 401         }
 402
 403         globfree(&gl);
 404         vlist_flush(&ubusd_acl_files);
 405         ubusd_acl_seq++;
 406         ubusd_send_event(NULL, "ubus.acl.sequence", ubusd_create_sequence_event_msg, NULL);
 407 }
 408
 409 static void
 410 ubusd_reply_add(struct ubus_object *obj)
 411 {
 412         struct ubusd_acl_obj *acl;
 413
 414         if (!obj->path.key)
 415                 return;
 416
 417         acl = avl_find_ge_element(&ubusd_acls, obj->path.key, acl, avl);
 418         avl_for_element_to_last(&ubusd_acls, acl, acl, avl) {
 419                 void *c;
 420
 421                 if (!acl->priv)
 422                         continue;
 423
 424                 if (!ubusd_acl_match_path(obj->path.key, acl->avl.key, NULL))
 425                         continue;
 426
 427                 c = blobmsg_open_table(&b, NULL);
 428                 blobmsg_add_string(&b, "obj", obj->path.key);
 429                 if (acl->user)
 430                         blobmsg_add_string(&b, "user", acl->user);
 431                 if (acl->group)
 432                         blobmsg_add_string(&b, "group", acl->group);
 433
 434                 blobmsg_add_field(&b, blobmsg_type(acl->priv), "acl",
 435                         blobmsg_data(acl->priv), blobmsg_data_len(acl->priv));
 436
 437                 blobmsg_close_table(&b, c);
 438         }
 439 }
 440 static int ubusd_reply_query(struct ubus_client *cl, struct ubus_msg_buf *ub, struct blob_attr **attr, struct blob_attr *msg)
 441 {
 442         struct ubus_object *obj;
 443         void *d, *a;
 444
 445         if (!attr[UBUS_ATTR_OBJID])
 446                 return UBUS_STATUS_INVALID_ARGUMENT;
 447
 448         obj = ubusd_find_object(blob_get_u32(attr[UBUS_ATTR_OBJID]));
 449         if (!obj)
 450                 return UBUS_STATUS_NOT_FOUND;
 451
 452         blob_buf_init(&b, 0);
 453         blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id.id);
 454         d = blob_nest_start(&b, UBUS_ATTR_DATA);
 455
 456         blobmsg_add_u32(&b, "seq", ubusd_acl_seq);
 457         a = blobmsg_open_array(&b, "acl");
 458         list_for_each_entry(obj, &cl->objects, list)
 459                 ubusd_reply_add(obj);
 460         blobmsg_close_table(&b, a);
 461
 462         blob_nest_end(&b, d);
 463
 464         ubus_proto_send_msg_from_blob(cl, ub, UBUS_MSG_DATA);
 465
 466         return 0;
 467 }
 468
 469 static int ubusd_acl_recv(struct ubus_client *cl, struct ubus_msg_buf *ub, const char *method, struct blob_attr *msg)
 470 {
 471         if (!strcmp(method, "query"))
 472                 return ubusd_reply_query(cl, ub, ubus_parse_msg(ub->data), msg);
 473
 474         return UBUS_STATUS_INVALID_COMMAND;
 475 }
 476
 477 void ubusd_acl_init(void)
 478 {
 479         avl_init(&ubusd_acls, ubusd_acl_match_path, true, NULL);
 480         acl_obj = ubusd_create_object_internal(NULL, UBUS_SYSTEM_OBJECT_ACL);
 481         acl_obj->recv_msg = ubusd_acl_recv;
 482 }