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         while (acl) {
 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                         acl = avl_next_element(acl, avl);
 116                         continue;
 117                 }
 118
 119                 switch (type) {
 120                 case UBUS_ACL_PUBLISH:
 121                         if (acl->publish)
 122                                 return 0;
 123                         break;
 124
 125                 case UBUS_ACL_SUBSCRIBE:
 126                         if (acl->subscribe)
 127                                 return 0;
 128                         break;
 129
 130                 case UBUS_ACL_ACCESS:
 131                         if (acl->methods)
 132                                 blobmsg_for_each_attr(cur, acl->methods, rem)
 133                                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 134                                                 if (!ubusd_acl_match_path(method, blobmsg_get_string(cur), NULL))
 135                                                         return 0;
 136                         break;
 137                 }
 138                 acl = avl_next_element(acl, avl);
 139         }
 140
 141         return -1;
 142 }
 143
 144 int
 145 ubusd_acl_init_client(struct ubus_client *cl, int fd)
 146 {
 147         struct ucred cred;
 148         struct passwd *pwd;
 149         struct group *group;
 150
 151 #ifdef SO_PEERCRED
 152         unsigned int len = sizeof(struct ucred);
 153
 154         if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) == -1)
 155                 return -1;
 156 #else
 157         memset(&cred, 0, sizeof(cred));
 158 #endif
 159
 160         pwd = getpwuid(cred.uid);
 161         if (!pwd)
 162                 return -1;
 163
 164         group = getgrgid(cred.gid);
 165         if (!group)
 166                 return -1;
 167
 168         cl->uid = cred.uid;
 169         cl->gid = cred.gid;
 170
 171         cl->group = strdup(group->gr_name);
 172         cl->user = strdup(pwd->pw_name);
 173
 174         return 0;
 175 }
 176
 177 static void
 178 ubusd_acl_file_free(struct ubusd_acl_file *file)
 179 {
 180         struct ubusd_acl_obj *p, *q;
 181
 182         list_for_each_entry_safe(p, q, &file->acl, list) {
 183                 avl_delete(&ubusd_acls, &p->avl);
 184                 list_del(&p->list);
 185                 free(p);
 186         }
 187
 188         free(file);
 189 }
 190
 191 enum {
 192         ACL_ACCESS_METHODS,
 193         ACL_ACCESS_TAGS,
 194         ACL_ACCESS_PRIV,
 195         __ACL_ACCESS_MAX
 196 };
 197
 198 static const struct blobmsg_policy acl_obj_policy[__ACL_ACCESS_MAX] = {
 199         [ACL_ACCESS_METHODS] = { .name = "methods", .type = BLOBMSG_TYPE_ARRAY },
 200         [ACL_ACCESS_TAGS] = { .name = "tags", .type = BLOBMSG_TYPE_ARRAY },
 201         [ACL_ACCESS_PRIV] = { .name = "acl", .type = BLOBMSG_TYPE_TABLE },
 202 };
 203
 204 static struct ubusd_acl_obj*
 205 ubusd_acl_alloc_obj(struct ubusd_acl_file *file, const char *obj)
 206 {
 207         struct ubusd_acl_obj *o;
 208         char *k;
 209
 210         o = calloc_a(sizeof(*o), &k, strlen(obj) + 1);
 211         o->user = file->user;
 212         o->group = file->group;
 213         o->avl.key = k;
 214         strcpy(k, obj);
 215
 216         while (*k) {
 217                 if (*k == '*')
 218                         *k = '\t';
 219                 k++;
 220         }
 221
 222         list_add(&o->list, &file->acl);
 223         avl_insert(&ubusd_acls, &o->avl);
 224
 225         return o;
 226 }
 227
 228 static void
 229 ubusd_acl_add_access(struct ubusd_acl_file *file, struct blob_attr *obj)
 230 {
 231         struct blob_attr *tb[__ACL_ACCESS_MAX];
 232         struct ubusd_acl_obj *o;
 233
 234         blobmsg_parse(acl_obj_policy, __ACL_ACCESS_MAX, tb, blobmsg_data(obj),
 235                       blobmsg_data_len(obj));
 236
 237         if (!tb[ACL_ACCESS_METHODS] && !tb[ACL_ACCESS_TAGS] && !tb[ACL_ACCESS_PRIV])
 238                 return;
 239
 240         o = ubusd_acl_alloc_obj(file, blobmsg_name(obj));
 241
 242         o->methods = tb[ACL_ACCESS_METHODS];
 243         o->tags = tb[ACL_ACCESS_TAGS];
 244         o->priv = tb[ACL_ACCESS_PRIV];
 245
 246         if (file->user || file->group)
 247                 file->ok = 1;
 248 }
 249
 250 static void
 251 ubusd_acl_add_subscribe(struct ubusd_acl_file *file, const char *obj)
 252 {
 253         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 254
 255         o->subscribe = true;
 256 }
 257
 258 static void
 259 ubusd_acl_add_publish(struct ubusd_acl_file *file, const char *obj)
 260 {
 261         struct ubusd_acl_obj *o = ubusd_acl_alloc_obj(file, obj);
 262
 263         o->publish = true;
 264 }
 265
 266 enum {
 267         ACL_USER,
 268         ACL_GROUP,
 269         ACL_ACCESS,
 270         ACL_PUBLISH,
 271         ACL_SUBSCRIBE,
 272         ACL_INHERIT,
 273         __ACL_MAX
 274 };
 275
 276 static const struct blobmsg_policy acl_policy[__ACL_MAX] = {
 277         [ACL_USER] = { .name = "user", .type = BLOBMSG_TYPE_STRING },
 278         [ACL_GROUP] = { .name = "group", .type = BLOBMSG_TYPE_STRING },
 279         [ACL_ACCESS] = { .name = "access", .type = BLOBMSG_TYPE_TABLE },
 280         [ACL_PUBLISH] = { .name = "publish", .type = BLOBMSG_TYPE_ARRAY },
 281         [ACL_SUBSCRIBE] = { .name = "subscribe", .type = BLOBMSG_TYPE_ARRAY },
 282         [ACL_INHERIT] = { .name = "inherit", .type = BLOBMSG_TYPE_ARRAY },
 283 };
 284
 285 static void
 286 ubusd_acl_file_add(struct ubusd_acl_file *file)
 287 {
 288         struct blob_attr *tb[__ACL_MAX], *cur;
 289         int rem;
 290
 291         blobmsg_parse(acl_policy, __ACL_MAX, tb, blob_data(file->blob),
 292                       blob_len(file->blob));
 293
 294         if (tb[ACL_USER])
 295                 file->user = blobmsg_get_string(tb[ACL_USER]);
 296         else if (tb[ACL_GROUP])
 297                 file->group = blobmsg_get_string(tb[ACL_GROUP]);
 298         else
 299                 return;
 300
 301         if (tb[ACL_ACCESS])
 302                 blobmsg_for_each_attr(cur, tb[ACL_ACCESS], rem)
 303                         ubusd_acl_add_access(file, cur);
 304
 305         if (tb[ACL_SUBSCRIBE])
 306                 blobmsg_for_each_attr(cur, tb[ACL_SUBSCRIBE], rem)
 307                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 308                                 ubusd_acl_add_subscribe(file, blobmsg_get_string(cur));
 309
 310         if (tb[ACL_PUBLISH])
 311                 blobmsg_for_each_attr(cur, tb[ACL_PUBLISH], rem)
 312                         if (blobmsg_type(cur) == BLOBMSG_TYPE_STRING)
 313                                 ubusd_acl_add_publish(file, blobmsg_get_string(cur));
 314 }
 315
 316 static void
 317 ubusd_acl_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 318         struct vlist_node *node_old)
 319 {
 320         struct ubusd_acl_file *file;
 321
 322         if (node_old) {
 323                 file = container_of(node_old, struct ubusd_acl_file, avl);
 324                 ubusd_acl_file_free(file);
 325         }
 326
 327         if (node_new) {
 328                 file = container_of(node_new, struct ubusd_acl_file, avl);
 329                 ubusd_acl_file_add(file);
 330         }
 331 }
 332
 333 static struct ubus_msg_buf *
 334 ubusd_create_sequence_event_msg(void *priv, const char *id)
 335 {
 336         void *s;
 337
 338         blob_buf_init(&b, 0);
 339         blob_put_int32(&b, UBUS_ATTR_OBJID, 0);
 340         blob_put_string(&b, UBUS_ATTR_METHOD, id);
 341         s = blob_nest_start(&b, UBUS_ATTR_DATA);
 342         blobmsg_add_u32(&b, "sequence", ubusd_acl_seq);
 343         blob_nest_end(&b, s);
 344
 345         return ubus_msg_new(b.head, blob_raw_len(b.head), true);
 346 }
 347
 348 static VLIST_TREE(ubusd_acl_files, avl_strcmp, ubusd_acl_update_cb, false, false);
 349
 350 static int
 351 ubusd_acl_load_file(const char *filename)
 352 {
 353         struct ubusd_acl_file *file;
 354         void *blob;
 355
 356         blob_buf_init(&bbuf, 0);
 357         if (!blobmsg_add_json_from_file(&bbuf, filename)) {
 358                 syslog(LOG_ERR, "failed to parse %s\n", filename);
 359                 return -1;
 360         }
 361
 362         file = calloc_a(sizeof(*file), &blob, blob_raw_len(bbuf.head));
 363         if (!file)
 364                 return -1;
 365
 366         file->blob = blob;
 367
 368         memcpy(blob, bbuf.head, blob_raw_len(bbuf.head));
 369         INIT_LIST_HEAD(&file->acl);
 370
 371         vlist_add(&ubusd_acl_files, &file->avl, filename);
 372         syslog(LOG_INFO, "loading %s\n", filename);
 373
 374         return 0;
 375 }
 376
 377 void
 378 ubusd_acl_load(void)
 379 {
 380         struct stat st;
 381         glob_t gl;
 382         int j;
 383         const char *suffix = "/*.json";
 384         char *path = alloca(strlen(ubusd_acl_dir) + strlen(suffix) + 1);
 385
 386         sprintf(path, "%s%s", ubusd_acl_dir, suffix);
 387         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 388                 return;
 389
 390         vlist_update(&ubusd_acl_files);
 391         for (j = 0; j < gl.gl_pathc; j++) {
 392                 if (stat(gl.gl_pathv[j], &st) || !S_ISREG(st.st_mode))
 393                         continue;
 394
 395                 if (st.st_uid || st.st_gid) {
 396                         syslog(LOG_ERR, "%s has wrong owner\n", gl.gl_pathv[j]);
 397                         continue;
 398                 }
 399                 if (st.st_mode & (S_IWOTH | S_IWGRP | S_IXOTH)) {
 400                         syslog(LOG_ERR, "%s has wrong permissions\n", gl.gl_pathv[j]);
 401                         continue;
 402                 }
 403                 ubusd_acl_load_file(gl.gl_pathv[j]);
 404         }
 405
 406         globfree(&gl);
 407         vlist_flush(&ubusd_acl_files);
 408         ubusd_acl_seq++;
 409         ubusd_send_event(NULL, "ubus.acl.sequence", ubusd_create_sequence_event_msg, NULL);
 410 }
 411
 412 static void
 413 ubusd_reply_add(struct ubus_object *obj)
 414 {
 415         struct ubusd_acl_obj *acl;
 416
 417         if (!obj->path.key)
 418                 return;
 419         acl = avl_find_ge_element(&ubusd_acls, obj->path.key, acl, avl);
 420         while (acl && !avl_is_last(&ubusd_acls, &acl->avl) &&
 421                       !ubusd_acl_match_path(obj->path.key, acl->avl.key, NULL)) {
 422
 423                 if (acl->priv) {
 424                         void *c = blobmsg_open_table(&b, NULL);
 425
 426                         blobmsg_add_string(&b, "obj", obj->path.key);
 427                         if (acl->user)
 428                                 blobmsg_add_string(&b, "user", acl->user);
 429                         if (acl->group)
 430                                 blobmsg_add_string(&b, "group", acl->group);
 431
 432                         if (acl->priv)
 433                                 blobmsg_add_field(&b, blobmsg_type(acl->priv), "acl",
 434                                         blobmsg_data(acl->priv), blobmsg_data_len(acl->priv));
 435
 436                         blobmsg_close_table(&b, c);
 437                 }
 438                 acl = avl_next_element(acl, avl);
 439         }
 440 }
 441 static int ubusd_reply_query(struct ubus_client *cl, struct ubus_msg_buf *ub, struct blob_attr **attr, struct blob_attr *msg)
 442 {
 443         struct ubus_object *obj;
 444         void *d, *a;
 445
 446         if (!attr[UBUS_ATTR_OBJID])
 447                 return UBUS_STATUS_INVALID_ARGUMENT;
 448
 449         obj = ubusd_find_object(blob_get_u32(attr[UBUS_ATTR_OBJID]));
 450         if (!obj)
 451                 return UBUS_STATUS_NOT_FOUND;
 452
 453         blob_buf_init(&b, 0);
 454         blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id.id);
 455         d = blob_nest_start(&b, UBUS_ATTR_DATA);
 456
 457         blobmsg_add_u32(&b, "seq", ubusd_acl_seq);
 458         a = blobmsg_open_array(&b, "acl");
 459         list_for_each_entry(obj, &cl->objects, list)
 460                 ubusd_reply_add(obj);
 461         blobmsg_close_table(&b, a);
 462
 463         blob_nest_end(&b, d);
 464
 465         ubus_proto_send_msg_from_blob(cl, ub, UBUS_MSG_DATA);
 466
 467         return 0;
 468 }
 469
 470 static int ubusd_acl_recv(struct ubus_client *cl, struct ubus_msg_buf *ub, const char *method, struct blob_attr *msg)
 471 {
 472         if (!strcmp(method, "query"))
 473                 return ubusd_reply_query(cl, ub, ubus_parse_msg(ub->data), msg);
 474
 475         return UBUS_STATUS_INVALID_COMMAND;
 476 }
 477
 478 void ubusd_acl_init(void)
 479 {
 480         avl_init(&ubusd_acls, ubusd_acl_match_path, true, NULL);
 481         acl_obj = ubusd_create_object_internal(NULL, UBUS_SYSTEM_OBJECT_ACL);
 482         acl_obj->recv_msg = ubusd_acl_recv;
 483 }