rc.c

   1 // SPDX-License-Identifier: ISC OR MIT
   2 /*
   3  * rpcd - UBUS RPC server
   4  *
   5  * Copyright (C) 2020 Rafał Miłecki <rafal@milecki.pl>
   6  */
   7
   8 #include <dirent.h>
   9 #include <fcntl.h>
  10 #include <linux/limits.h>
  11 #include <sys/stat.h>
  12 #include <sys/wait.h>
  13
  14 #include <libubox/blobmsg.h>
  15 #include <libubox/ulog.h>
  16 #include <libubox/uloop.h>
  17 #include <libubus.h>
  18
  19 #include <rpcd/rc.h>
  20
  21 #define RC_LIST_EXEC_TIMEOUT_MS                 3000
  22
  23 enum {
  24         RC_INIT_NAME,
  25         RC_INIT_ACTION,
  26         __RC_INIT_MAX
  27 };
  28
  29 static const struct blobmsg_policy rc_init_policy[] = {
  30         [RC_INIT_NAME] = { "name", BLOBMSG_TYPE_STRING },
  31         [RC_INIT_ACTION] = { "action", BLOBMSG_TYPE_STRING },
  32 };
  33
  34 struct rc_list_context {
  35         struct uloop_process process;
  36         struct uloop_timeout timeout;
  37         struct ubus_context *ctx;
  38         struct ubus_request_data req;
  39         struct blob_buf *buf;
  40         DIR *dir;
  41
  42         /* Info about currently processed init.d entry */
  43         struct {
  44                 char path[PATH_MAX];
  45                 const char *d_name;
  46                 int start;
  47                 int stop;
  48                 bool enabled;
  49                 bool running;
  50         } entry;
  51 };
  52
  53 static void rc_list_readdir(struct rc_list_context *c);
  54
  55 /**
  56  * rc_check_script - check if script is safe to execute as root
  57  *
  58  * Check if it's owned by root and if only root can modify it.
  59  */
  60 static int rc_check_script(const char *path)
  61 {
  62         struct stat s;
  63
  64         if (stat(path, &s))
  65                 return UBUS_STATUS_NOT_FOUND;
  66
  67         if (s.st_uid != 0 || s.st_gid != 0 || !(s.st_mode & S_IXUSR) || (s.st_mode & S_IWOTH))
  68                 return UBUS_STATUS_PERMISSION_DENIED;
  69
  70         return UBUS_STATUS_OK;
  71 }
  72
  73 static void rc_list_add_table(struct rc_list_context *c)
  74 {
  75         void *e;
  76
  77         e = blobmsg_open_table(c->buf, c->entry.d_name);
  78
  79         if (c->entry.start >= 0)
  80                 blobmsg_add_u16(c->buf, "start", c->entry.start);
  81         if (c->entry.stop >= 0)
  82                 blobmsg_add_u16(c->buf, "stop", c->entry.stop);
  83         blobmsg_add_u8(c->buf, "enabled", c->entry.enabled);
  84         blobmsg_add_u8(c->buf, "running", c->entry.running);
  85
  86         blobmsg_close_table(c->buf, e);
  87 }
  88
  89 static void rpc_list_exec_timeout_cb(struct uloop_timeout *t)
  90 {
  91         struct rc_list_context *c = container_of(t, struct rc_list_context, timeout);
  92
  93         ULOG_WARN("Timeout waiting for %s\n", c->entry.path);
  94
  95         uloop_process_delete(&c->process);
  96         kill(c->process.pid, SIGKILL);
  97
  98         rc_list_readdir(c);
  99 }
 100
 101 /**
 102  * rc_exec - execute a file and call callback on complete
 103  */
 104 static int rc_list_exec(struct rc_list_context *c, const char *action, uloop_process_handler cb)
 105 {
 106         pid_t pid;
 107         int err;
 108         int fd;
 109
 110         pid = fork();
 111         switch (pid) {
 112         case -1:
 113                 return -errno;
 114         case 0:
 115                 /* Set stdin, stdout & stderr to /dev/null */
 116                 fd = open("/dev/null", O_RDWR);
 117                 if (fd >= 0) {
 118                         dup2(fd, 0);
 119                         dup2(fd, 1);
 120                         dup2(fd, 2);
 121                         if (fd > 2)
 122                                 close(fd);
 123                 }
 124
 125                 uloop_end();
 126
 127                 execl(c->entry.path, c->entry.path, action, NULL);
 128                 exit(errno);
 129         default:
 130                 c->process.pid = pid;
 131                 c->process.cb = cb;
 132
 133                 err = uloop_process_add(&c->process);
 134                 if (err)
 135                         return err;
 136
 137                 c->timeout.cb = rpc_list_exec_timeout_cb;
 138                 err = uloop_timeout_set(&c->timeout, RC_LIST_EXEC_TIMEOUT_MS);
 139                 if (err) {
 140                         uloop_process_delete(&c->process);
 141                         return err;
 142                 }
 143
 144                 return 0;
 145         }
 146 }
 147
 148 static void rc_list_exec_running_cb(struct uloop_process *p, int stat)
 149 {
 150         struct rc_list_context *c = container_of(p, struct rc_list_context, process);
 151
 152         uloop_timeout_cancel(&c->timeout);
 153
 154         c->entry.running = !stat;
 155         rc_list_add_table(c);
 156
 157         rc_list_readdir(c);
 158 }
 159
 160 static void rc_list_readdir(struct rc_list_context *c)
 161 {
 162         struct dirent *e;
 163         FILE *fp;
 164
 165         e = readdir(c->dir);
 166         if (!e) {
 167                 closedir(c->dir);
 168                 ubus_send_reply(c->ctx, &c->req, c->buf->head);
 169                 ubus_complete_deferred_request(c->ctx, &c->req, UBUS_STATUS_OK);
 170                 return;
 171         }
 172
 173         if (!strcmp(e->d_name, ".") || !strcmp(e->d_name, ".."))
 174                 goto next;
 175
 176         memset(&c->entry, 0, sizeof(c->entry));
 177         c->entry.start = -1;
 178         c->entry.stop = -1;
 179
 180         snprintf(c->entry.path, sizeof(c->entry.path), "/etc/init.d/%s", e->d_name);
 181         if (rc_check_script(c->entry.path))
 182                 goto next;
 183
 184         c->entry.d_name = e->d_name;
 185
 186         fp = fopen(c->entry.path, "r");
 187         if (fp) {
 188                 struct stat s;
 189                 char path[PATH_MAX];
 190                 char line[32];
 191                 bool beginning;
 192
 193                 beginning = true;
 194                 while (c->entry.start < 0 && c->entry.stop < 0 && fgets(line, sizeof(line), fp)) {
 195                         if (beginning) {
 196                                 if (!strncmp(line, "START=", 6)) {
 197                                         c->entry.start = strtoul(line + 6, NULL, 0);
 198                                 } else if (!strncmp(line, "STOP=", 5)) {
 199                                         c->entry.stop = strtoul(line + 5, NULL, 0);
 200                                 }
 201                         }
 202
 203                         beginning = !!strchr(line, '\n');
 204                 }
 205                 fclose(fp);
 206
 207                 if (c->entry.start >= 0) {
 208                         snprintf(path, sizeof(path), "/etc/rc.d/S%02d%s", c->entry.start, c->entry.d_name);
 209                         if (!stat(path, &s) && (s.st_mode & S_IXUSR))
 210                                 c->entry.enabled = true;
 211                 }
 212         }
 213
 214         if (rc_list_exec(c, "running", rc_list_exec_running_cb))
 215                 goto next;
 216
 217         return;
 218 next:
 219         rc_list_readdir(c);
 220 }
 221
 222 /**
 223  * rc_list - allocate listing context and start reading directory
 224  */
 225 static int rc_list(struct ubus_context *ctx, struct ubus_object *obj,
 226                    struct ubus_request_data *req, const char *method,
 227                    struct blob_attr *msg)
 228 {
 229         static struct blob_buf buf;
 230         struct rc_list_context *c;
 231
 232         blob_buf_init(&buf, 0);
 233
 234         c = calloc(1, sizeof(*c));
 235         if (!c)
 236                 return UBUS_STATUS_UNKNOWN_ERROR;
 237
 238         c->ctx = ctx;
 239         c->buf = &buf;
 240         c->dir = opendir("/etc/init.d");
 241         if (!c->dir) {
 242                 free(c);
 243                 return UBUS_STATUS_UNKNOWN_ERROR;
 244         }
 245
 246         ubus_defer_request(ctx, req, &c->req);
 247
 248         rc_list_readdir(c);
 249
 250         return 0; /* Deferred */
 251 }
 252
 253 struct rc_init_context {
 254         struct uloop_process process;
 255         struct ubus_context *ctx;
 256         struct ubus_request_data req;
 257 };
 258
 259 static void rc_init_cb(struct uloop_process *p, int stat)
 260 {
 261         struct rc_init_context *c = container_of(p, struct rc_init_context, process);
 262
 263         ubus_complete_deferred_request(c->ctx, &c->req, UBUS_STATUS_OK);
 264
 265         free(c);
 266 }
 267
 268 static int rc_init(struct ubus_context *ctx, struct ubus_object *obj,
 269                    struct ubus_request_data *req, const char *method,
 270                    struct blob_attr *msg)
 271 {
 272         struct blob_attr *tb[__RC_INIT_MAX];
 273         struct rc_init_context *c;
 274         char path[PATH_MAX];
 275         const char *action;
 276         const char *name;
 277         const char *chr;
 278         pid_t pid;
 279         int err;
 280         int fd;
 281
 282         blobmsg_parse(rc_init_policy, __RC_INIT_MAX, tb, blobmsg_data(msg), blobmsg_data_len(msg));
 283
 284         if (!tb[RC_INIT_NAME] || !tb[RC_INIT_ACTION])
 285                 return UBUS_STATUS_INVALID_ARGUMENT;
 286
 287         name = blobmsg_get_string(tb[RC_INIT_NAME]);
 288
 289         /* Validate script name */
 290         for (chr = name; (chr = strchr(chr, '.')); chr++) {
 291                 if (*(chr + 1) == '.')
 292                         return UBUS_STATUS_INVALID_ARGUMENT;
 293         }
 294         if (strchr(name, '/'))
 295                 return UBUS_STATUS_INVALID_ARGUMENT;
 296
 297         snprintf(path, sizeof(path), "/etc/init.d/%s", name);
 298
 299         /* Validate script privileges */
 300         err = rc_check_script(path);
 301         if (err)
 302                 return err;
 303
 304         action = blobmsg_get_string(tb[RC_INIT_ACTION]);
 305         if (strcmp(action, "disable") &&
 306             strcmp(action, "enable") &&
 307             strcmp(action, "stop") &&
 308             strcmp(action, "start") &&
 309             strcmp(action, "restart") &&
 310             strcmp(action, "reload"))
 311                 return UBUS_STATUS_INVALID_ARGUMENT;
 312
 313         c = calloc(1, sizeof(*c));
 314         if (!c)
 315                 return UBUS_STATUS_UNKNOWN_ERROR;
 316
 317         pid = fork();
 318         switch (pid) {
 319         case -1:
 320                 free(c);
 321                 return UBUS_STATUS_UNKNOWN_ERROR;
 322         case 0:
 323                 /* Set stdin, stdout & stderr to /dev/null */
 324                 fd = open("/dev/null", O_RDWR);
 325                 if (fd >= 0) {
 326                         dup2(fd, 0);
 327                         dup2(fd, 1);
 328                         dup2(fd, 2);
 329                         if (fd > 2)
 330                                 close(fd);
 331                 }
 332
 333                 uloop_end();
 334
 335                 execl(path, path, action, NULL);
 336                 exit(errno);
 337         default:
 338                 c->ctx = ctx;
 339                 c->process.pid = pid;
 340                 c->process.cb = rc_init_cb;
 341                 uloop_process_add(&c->process);
 342
 343                 ubus_defer_request(ctx, req, &c->req);
 344
 345                 return 0; /* Deferred */
 346         }
 347 }
 348
 349 int rpc_rc_api_init(struct ubus_context *ctx)
 350 {
 351         static const struct ubus_method rc_methods[] = {
 352                 UBUS_METHOD_NOARG("list", rc_list),
 353                 UBUS_METHOD("init", rc_init, rc_init_policy),
 354         };
 355
 356         static struct ubus_object_type rc_type =
 357                 UBUS_OBJECT_TYPE("rc", rc_methods);
 358
 359         static struct ubus_object obj = {
 360                 .name = "rc",
 361                 .type = &rc_type,
 362                 .methods = rc_methods,
 363                 .n_methods = ARRAY_SIZE(rc_methods),
 364         };
 365
 366         return ubus_add_object(ctx, &obj);
 367 }