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 static struct blob_buf bbuf;
  66 static struct avl_tree ubusd_acls;
  67 static int ubusd_acl_seq;
  68 static struct ubus_object *acl_obj;
  69
  70 static int
  71 ubusd_acl_match_path(const void *k1, const void *k2, void *ptr)
  72 {
  73         const char *name = k1;
  74         const char *match = k2;
  75         char *wildcard = strstr(match, "\t");
  76
  77         if (wildcard)
  78                 return strncmp(name, match, wildcard - match);
  79
  80         return strcmp(name, match);
  81 }
  82
  83 static int
  84 ubusd_acl_match_cred(struct ubus_client *cl, struct ubusd_acl_obj *obj)
  85 {
  86         if (obj->user && !strcmp(cl->user, obj->user))
  87                 return 0;
  88
  89         if (obj->group && !strcmp(cl->group, obj->group))
  90                 return 0;
  91
  92         return -1;
  93 }
  94
  95 int
  96 ubusd_acl_check(struct ubus_client *cl, const char *obj,
  97                 const char *method, enum ubusd_acl_type type)
  98 {
  99         struct ubusd_acl_obj *acl;
 100         struct blob_attr *cur;
 101         int rem;
 102
 103         if (!cl->gid && !cl->uid)
 104                 return 0;
 105
 106         acl = avl_find_ge_element(&ubusd_acls, obj, acl, avl);
 107         while (acl) {
 108                 int diff = ubusd_acl_match_path(obj, acl->avl.key, NULL);
 109
 110                 if (diff)
 111                         break;
 112
 113                 if (ubusd_acl_match_cred(cl, acl)) {
 114                         acl = avl_next_element(acl, avl);
 115                         continue;
 116                 }
 117
 118                 switch (type) {
 119                 case UBUS_ACL_PUBLISH:
 120                         if (acl->publish)
 121                                 return 0;
 122                         break;
 123
 124                 case UBUS_ACL_SUBSCRIBE:
 125                         if (acl->subscribe)
 126                                 return 0;
 127                         break;
 128
 129                 case UBUS_ACL_ACCESS:
 130                         if (acl->methods)
 131                                 blobmsg_for_each_attr(cur, acl->methods, rem)
 132                                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 133                                                 if (!ubusd_acl_match_path(method, blobmsg_get_string(cur), NULL))
 134                                                         return 0;
 135                         break;
 136                 }
 137                 acl = avl_next_element(acl, avl);
 138         }
 139
 140         return -1;
 141 }
 142
 143 int
 144 ubusd_acl_init_client(struct ubus_client *cl, int fd)
 145 {
 146         struct ucred cred;
 147         struct passwd *pwd;
 148         struct group *group;
 149
 150 #ifdef SO_PEERCRED
 151         unsigned int len = sizeof(struct ucred);
 152
 153         if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) == -1)
 154                 return -1;
 155 #else
 156         memset(&cred, 0, sizeof(cred));
 157 #endif
 158
 159         pwd = getpwuid(cred.uid);
 160         if (!pwd)
 161                 return -1;
 162
 163         group = getgrgid(cred.gid);
 164         if (!group)
 165                 return -1;
 166
 167         cl->uid = cred.uid;
 168         cl->gid = cred.gid;
 169
 170         cl->group = strdup(group->gr_name);
 171         cl->user = strdup(pwd->pw_name);
 172
 173         return 0;
 174 }
 175
 176 static void
 177 ubusd_acl_file_free(struct ubusd_acl_file *file)
 178 {
 179         struct ubusd_acl_obj *p, *q;
 180
 181         list_for_each_entry_safe(p, q, &file->acl, list) {
 182                 avl_delete(&ubusd_acls, &p->avl);
 183                 list_del(&p->list);
 184                 free(p);
 185         }
 186
 187         free(file);
 188 }
 189
 190 enum {
 191         ACL_ACCESS_METHODS,
 192         ACL_ACCESS_TAGS,
 193         ACL_ACCESS_PRIV,
 194         __ACL_ACCESS_MAX
 195 };
 196
 197 static const struct blobmsg_policy acl_obj_policy[__ACL_ACCESS_MAX] = {
 198         [ACL_ACCESS_METHODS] = { .name = "methods", .type = BLOBMSG_TYPE_ARRAY },
 199         [ACL_ACCESS_TAGS] = { .name = "tags", .type = BLOBMSG_TYPE_ARRAY },
 200         [ACL_ACCESS_PRIV] = { .name = "acl", .type = BLOBMSG_TYPE_TABLE },
 201 };
 202
 203 static struct ubusd_acl_obj*
 204 ubusd_acl_alloc_obj(struct ubusd_acl_file *file, const char *obj)
 205 {
 206         struct ubusd_acl_obj *o;
 207         char *k;
 208
 209         o = calloc_a(sizeof(*o), &k, strlen(obj) + 1);
 210         o->user = file->user;
 211         o->group = file->group;
 212         o->avl.key = k;
 213         strcpy(k, obj);
 214
 215         while (*k) {
 216                 if (*k == '*')
 217                         *k = '\t';
 218                 k++;
 219         }
 220
 221         list_add(&o->list, &file->acl);
 222         avl_insert(&ubusd_acls, &o->avl);
 223
 224         return o;
 225 }
 226
 227 static void
 228 ubusd_acl_add_access(struct ubusd_acl_file *file, struct blob_attr *obj)
 229 {
 230         struct blob_attr *tb[__ACL_ACCESS_MAX];
 231         struct ubusd_acl_obj *o;
 232
 233         blobmsg_parse(acl_obj_policy, __ACL_ACCESS_MAX, tb, blobmsg_data(obj),
 234                       blobmsg_data_len(obj));
 235
 236         if (!tb[ACL_ACCESS_METHODS] && !tb[ACL_ACCESS_TAGS] && !tb[ACL_ACCESS_PRIV])
 237                 return;
 238
 239         o = ubusd_acl_alloc_obj(file, blobmsg_name(obj));
 240
 241         o->methods = tb[ACL_ACCESS_METHODS];
 242         o->tags = tb[ACL_ACCESS_TAGS];
 243         o->priv = tb[ACL_ACCESS_PRIV];
 244
 245         if (file->user || file->group)
 246                 file->ok = 1;
 247 }
 248
 249 static void
 250 ubusd_acl_add_subscribe(struct ubusd_acl_file *file, const char *obj)
 251 {
 252         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 253
 254         o->subscribe = true;
 255 }
 256
 257 static void
 258 ubusd_acl_add_publish(struct ubusd_acl_file *file, const char *obj)
 259 {
 260         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 261
 262         o->publish = true;
 263 }
 264
 265 enum {
 266         ACL_USER,
 267         ACL_GROUP,
 268         ACL_ACCESS,
 269         ACL_PUBLISH,
 270         ACL_SUBSCRIBE,
 271         ACL_INHERIT,
 272         __ACL_MAX
 273 };
 274
 275 static const struct blobmsg_policy acl_policy[__ACL_MAX] = {
 276         [ACL_USER] = { .name = "user", .type = BLOBMSG_TYPE_STRING },
 277         [ACL_GROUP] = { .name = "group", .type = BLOBMSG_TYPE_STRING },
 278         [ACL_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_TABLE },
 279         [ACL_PUBLISH] = { .name = "publish", .type = BLOBMSG_TYPE_ARRAY },
 280         [ACL_SUBSCRIBE] = { .name = "subscribe", .type = BLOBMSG_TYPE_ARRAY },
 281         [ACL_INHERIT] = { .name = "inherit", .type = BLOBMSG_TYPE_ARRAY },
 282 };
 283
 284 static void
 285 ubusd_acl_file_add(struct ubusd_acl_file *file)
 286 {
 287         struct blob_attr *tb[__ACL_MAX], *cur;
 288         int rem;
 289
 290         blobmsg_parse(acl_policy, __ACL_MAX, tb, blob_data(file->blob),
 291                       blob_len(file->blob));
 292
 293         if (tb[ACL_USER])
 294                 file->user = blobmsg_get_string(tb[ACL_USER]);
 295         else if (tb[ACL_GROUP])
 296                 file->group = blobmsg_get_string(tb[ACL_GROUP]);
 297         else
 298                 return;
 299
 300         if (!tb[ACL_ACCESS] && !tb[ACL_PUBLISH] && !tb[ACL_INHERIT])
 301                 return;
 302
 303         if (tb[ACL_ACCESS])
 304                 blobmsg_for_each_attr(cur, tb[ACL_ACCESS], rem)
 305                         ubusd_acl_add_access(file, cur);
 306
 307         if (tb[ACL_SUBSCRIBE])
 308                 blobmsg_for_each_attr(cur, tb[ACL_SUBSCRIBE], rem)
 309                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 310                                 ubusd_acl_add_subscribe(file, blobmsg_get_string(cur));
 311
 312         if (tb[ACL_PUBLISH])
 313                 blobmsg_for_each_attr(cur, tb[ACL_PUBLISH], rem)
 314                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 315                                 ubusd_acl_add_publish(file, blobmsg_get_string(cur));
 316 }
 317
 318 static void
 319 ubusd_acl_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 320         struct vlist_node *node_old)
 321 {
 322         struct ubusd_acl_file *file;
 323
 324         if (node_old) {
 325                 file = container_of(node_old, struct ubusd_acl_file, avl);
 326                 ubusd_acl_file_free(file);
 327         }
 328
 329         if (node_new) {
 330                 file = container_of(node_new, struct ubusd_acl_file, avl);
 331                 ubusd_acl_file_add(file);
 332         }
 333 }
 334
 335 static struct ubus_msg_buf *
 336 ubusd_create_sequence_event_msg(void *priv, const char *id)
 337 {
 338         void *s;
 339
 340         blob_buf_init(&b, 0);
 341         blob_put_int32(&b, UBUS_ATTR_OBJID, 0);
 342         blob_put_string(&b, UBUS_ATTR_METHOD, id);
 343         s = blob_nest_start(&b, UBUS_ATTR_DATA);
 344         blobmsg_add_u32(&b, "sequence", ubusd_acl_seq);
 345         blob_nest_end(&b, s);
 346
 347         return ubus_msg_new(b.head, blob_raw_len(b.head), true);
 348 }
 349
 350 static VLIST_TREE(ubusd_acl_files, avl_strcmp, ubusd_acl_update_cb, false, false);
 351
 352 static int
 353 ubusd_acl_load_file(const char *filename)
 354 {
 355         struct ubusd_acl_file *file;
 356         void *blob;
 357
 358         blob_buf_init(&bbuf, 0);
 359         if (!blobmsg_add_json_from_file(&bbuf, filename)) {
 360                 syslog(LOG_ERR, "failed to parse %s\n", filename);
 361                 return -1;
 362         }
 363
 364         file = calloc_a(sizeof(*file), &blob, blob_raw_len(bbuf.head));
 365         if (!file)
 366                 return -1;
 367
 368         file->blob = blob;
 369
 370         memcpy(blob, bbuf.head, blob_raw_len(bbuf.head));
 371         INIT_LIST_HEAD(&file->acl);
 372
 373         vlist_add(&ubusd_acl_files, &file->avl, filename);
 374         syslog(LOG_INFO, "loading %s\n", filename);
 375
 376         return 0;
 377 }
 378
 379 void
 380 ubusd_acl_load(void)
 381 {
 382         struct stat st;
 383         glob_t gl;
 384         int j;
 385
 386         if (glob("/usr/share/acl.d/*.json", GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 387                 return;
 388
 389         vlist_update(&ubusd_acl_files);
 390         for (j = 0; j < gl.gl_pathc; j++) {
 391                 if (stat(gl.gl_pathv[j], &st) || !S_ISREG(st.st_mode))
 392                         continue;
 393
 394                 if (st.st_uid || st.st_gid) {
 395                         syslog(LOG_ERR, "%s has wrong owner\n", gl.gl_pathv[j]);
 396                         continue;
 397                 }
 398                 if (st.st_mode & (S_IWOTH | S_IWGRP | S_IXOTH)) {
 399                         syslog(LOG_ERR, "%s has wrong permissions\n", gl.gl_pathv[j]);
 400                         continue;
 401                 }
 402                 ubusd_acl_load_file(gl.gl_pathv[j]);
 403         }
 404
 405         globfree(&gl);
 406         vlist_flush(&ubusd_acl_files);
 407         ubusd_acl_seq++;
 408         ubusd_send_event(NULL, "ubus.acl.sequence", ubusd_create_sequence_event_msg, NULL);
 409 }
 410
 411 static void
 412 ubusd_reply_add(struct ubus_object *obj)
 413 {
 414         struct ubusd_acl_obj *acl;
 415
 416         if (!obj->path.key)
 417                 return;
 418         acl = avl_find_ge_element(&ubusd_acls, obj->path.key, acl, avl);
 419         while (acl && !avl_is_last(&ubusd_acls, &acl->avl) &&
 420                       !ubusd_acl_match_path(obj->path.key, acl->avl.key, NULL)) {
 421
 422                 if (acl->priv) {
 423                         void *c = blobmsg_open_table(&b, NULL);
 424
 425                         blobmsg_add_string(&b, "obj", obj->path.key);
 426                         if (acl->user)
 427                                 blobmsg_add_string(&b, "user", acl->user);
 428                         if (acl->group)
 429                                 blobmsg_add_string(&b, "group", acl->group);
 430
 431                         if (acl->priv)
 432                                 blobmsg_add_field(&b, blobmsg_type(acl->priv), "acl",
 433                                         blobmsg_data(acl->priv), blobmsg_data_len(acl->priv));
 434
 435                         blobmsg_close_table(&b, c);
 436                 }
 437                 acl = avl_next_element(acl, avl);
 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 }