| 1 | /* When dealing with SLIP (to a pty, or ipif) we have separate rx, tx |
| 2 | and client buffers. When receiving we may read() any amount, not |
| 3 | just whole packets. When transmitting we need to bytestuff anyway, |
| 4 | and may be part-way through receiving. */ |
| 5 | |
| 6 | /* |
| 7 | * This file is part of secnet. |
| 8 | * See README for full list of copyright holders. |
| 9 | * |
| 10 | * secnet is free software; you can redistribute it and/or modify it |
| 11 | * under the terms of the GNU General Public License as published by |
| 12 | * the Free Software Foundation; either version 3 of the License, or |
| 13 | * (at your option) any later version. |
| 14 | * |
| 15 | * secnet is distributed in the hope that it will be useful, but |
| 16 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 18 | * General Public License for more details. |
| 19 | * |
| 20 | * You should have received a copy of the GNU General Public License |
| 21 | * version 3 along with secnet; if not, see |
| 22 | * https://www.gnu.org/licenses/gpl.html. |
| 23 | */ |
| 24 | |
| 25 | #include "secnet.h" |
| 26 | #include "util.h" |
| 27 | #include "netlink.h" |
| 28 | #include "process.h" |
| 29 | #include "unaligned.h" |
| 30 | #include <stdio.h> |
| 31 | #include <string.h> |
| 32 | #include <unistd.h> |
| 33 | #include <errno.h> |
| 34 | #include <fcntl.h> |
| 35 | |
| 36 | #define SLIP_END 192 |
| 37 | #define SLIP_ESC 219 |
| 38 | #define SLIP_ESCEND 220 |
| 39 | #define SLIP_ESCESC 221 |
| 40 | |
| 41 | struct slip { |
| 42 | struct netlink nl; |
| 43 | struct buffer_if *buff; /* We unstuff received packets into here |
| 44 | and send them to the netlink code. */ |
| 45 | bool_t pending_esc; |
| 46 | bool_t ignoring_packet; /* If this packet was corrupt or overlong, |
| 47 | we ignore everything up to the next END */ |
| 48 | netlink_deliver_fn *netlink_to_tunnel; |
| 49 | }; |
| 50 | |
| 51 | /* Generic SLIP mangling code */ |
| 52 | |
| 53 | static void slip_write(int fd, const uint8_t *p, size_t l) |
| 54 | { |
| 55 | while (l) { |
| 56 | ssize_t written=write(fd,p,l); |
| 57 | if (written<0) { |
| 58 | if (errno==EINTR) { |
| 59 | continue; |
| 60 | } else if (iswouldblock(errno)) { |
| 61 | lg_perror(0,"slip",0,M_ERR,errno,"write() (packet(s) lost)"); |
| 62 | return; |
| 63 | } else { |
| 64 | fatal_perror("slip_stuff: write()"); |
| 65 | } |
| 66 | } |
| 67 | assert(written>0); |
| 68 | assert((size_t)written<=l); |
| 69 | p+=written; |
| 70 | l-=written; |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | static void slip_stuff(struct slip *st, struct buffer_if *buf, int fd) |
| 75 | { |
| 76 | uint8_t txbuf[DEFAULT_BUFSIZE]; |
| 77 | uint8_t *i; |
| 78 | int32_t j=0; |
| 79 | |
| 80 | BUF_ASSERT_USED(buf); |
| 81 | |
| 82 | /* There's probably a much more efficient way of implementing this */ |
| 83 | txbuf[j++]=SLIP_END; |
| 84 | for (i=buf->start; i<(buf->start+buf->size); i++) { |
| 85 | switch (*i) { |
| 86 | case SLIP_END: |
| 87 | txbuf[j++]=SLIP_ESC; |
| 88 | txbuf[j++]=SLIP_ESCEND; |
| 89 | break; |
| 90 | case SLIP_ESC: |
| 91 | txbuf[j++]=SLIP_ESC; |
| 92 | txbuf[j++]=SLIP_ESCESC; |
| 93 | break; |
| 94 | default: |
| 95 | txbuf[j++]=*i; |
| 96 | break; |
| 97 | } |
| 98 | if ((j+2)>DEFAULT_BUFSIZE) { |
| 99 | slip_write(fd,txbuf,j); |
| 100 | j=0; |
| 101 | } |
| 102 | } |
| 103 | txbuf[j++]=SLIP_END; |
| 104 | slip_write(fd,txbuf,j); |
| 105 | BUF_FREE(buf); |
| 106 | } |
| 107 | |
| 108 | static void slip_unstuff(struct slip *st, uint8_t *buf, uint32_t l) |
| 109 | { |
| 110 | uint32_t i; |
| 111 | |
| 112 | BUF_ASSERT_USED(st->buff); |
| 113 | for (i=0; i<l; i++) { |
| 114 | int outputchr; |
| 115 | enum { OUTPUT_END = 256, OUTPUT_NOTHING = 257 }; |
| 116 | |
| 117 | if (!st->buff->size) |
| 118 | buffer_init(st->buff,calculate_max_start_pad()); |
| 119 | |
| 120 | if (st->pending_esc) { |
| 121 | st->pending_esc=False; |
| 122 | switch(buf[i]) { |
| 123 | case SLIP_ESCEND: |
| 124 | outputchr=SLIP_END; |
| 125 | break; |
| 126 | case SLIP_ESCESC: |
| 127 | outputchr=SLIP_ESC; |
| 128 | break; |
| 129 | default: |
| 130 | if (!st->ignoring_packet) { |
| 131 | Message(M_WARNING, "userv_afterpoll: bad SLIP escape" |
| 132 | " character, dropping packet\n"); |
| 133 | } |
| 134 | st->ignoring_packet=True; |
| 135 | outputchr=OUTPUT_NOTHING; |
| 136 | break; |
| 137 | } |
| 138 | } else { |
| 139 | switch (buf[i]) { |
| 140 | case SLIP_END: |
| 141 | outputchr=OUTPUT_END; |
| 142 | break; |
| 143 | case SLIP_ESC: |
| 144 | st->pending_esc=True; |
| 145 | outputchr=OUTPUT_NOTHING; |
| 146 | break; |
| 147 | default: |
| 148 | outputchr=buf[i]; |
| 149 | break; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | if (st->ignoring_packet) { |
| 154 | if (outputchr == OUTPUT_END) { |
| 155 | st->ignoring_packet=False; |
| 156 | st->buff->size=0; |
| 157 | } |
| 158 | } else { |
| 159 | if (outputchr == OUTPUT_END) { |
| 160 | if (st->buff->size>0) { |
| 161 | st->netlink_to_tunnel(&st->nl,st->buff); |
| 162 | BUF_ALLOC(st->buff,"userv_afterpoll"); |
| 163 | } |
| 164 | st->buff->size=0; |
| 165 | } else if (outputchr != OUTPUT_NOTHING) { |
| 166 | if (buf_remaining_space(st->buff)) { |
| 167 | buf_append_uint8(st->buff,outputchr); |
| 168 | } else { |
| 169 | Message(M_WARNING, "userv_afterpoll: dropping overlong" |
| 170 | " SLIP packet\n"); |
| 171 | st->ignoring_packet=True; |
| 172 | } |
| 173 | } |
| 174 | } |
| 175 | } |
| 176 | } |
| 177 | |
| 178 | static void slip_init(struct slip *st, struct cloc loc, dict_t *dict, |
| 179 | cstring_t name, netlink_deliver_fn *to_host) |
| 180 | { |
| 181 | st->netlink_to_tunnel= |
| 182 | netlink_init(&st->nl,st,loc,dict, |
| 183 | "netlink-userv-ipif",NULL,to_host); |
| 184 | st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"name",loc); |
| 185 | BUF_ALLOC(st->buff,"slip_init"); |
| 186 | st->pending_esc=False; |
| 187 | st->ignoring_packet=False; |
| 188 | } |
| 189 | |
| 190 | /* Connection to the kernel through userv-ipif */ |
| 191 | |
| 192 | struct userv { |
| 193 | struct slip slip; |
| 194 | int txfd; /* We transmit to userv */ |
| 195 | int rxfd; /* We receive from userv */ |
| 196 | cstring_t userv_path; |
| 197 | cstring_t service_user; |
| 198 | cstring_t service_name; |
| 199 | pid_t pid; |
| 200 | bool_t expecting_userv_exit; |
| 201 | }; |
| 202 | |
| 203 | static int userv_beforepoll(void *sst, struct pollfd *fds, int *nfds_io, |
| 204 | int *timeout_io) |
| 205 | { |
| 206 | struct userv *st=sst; |
| 207 | |
| 208 | if (st->rxfd!=-1) { |
| 209 | BEFOREPOLL_WANT_FDS(2); |
| 210 | fds[0].fd=st->txfd; |
| 211 | fds[0].events=0; /* Might want to pick up POLLOUT sometime */ |
| 212 | fds[1].fd=st->rxfd; |
| 213 | fds[1].events=POLLIN; |
| 214 | } else { |
| 215 | BEFOREPOLL_WANT_FDS(0); |
| 216 | } |
| 217 | return 0; |
| 218 | } |
| 219 | |
| 220 | static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds) |
| 221 | { |
| 222 | struct userv *st=sst; |
| 223 | uint8_t rxbuf[DEFAULT_BUFSIZE]; |
| 224 | int l; |
| 225 | |
| 226 | if (nfds==0) return; |
| 227 | |
| 228 | if (fds[1].revents&POLLERR) { |
| 229 | Message(M_ERR,"%s: userv_afterpoll: POLLERR!\n",st->slip.nl.name); |
| 230 | } |
| 231 | if (fds[1].revents&POLLIN) { |
| 232 | l=read(st->rxfd,rxbuf,DEFAULT_BUFSIZE); |
| 233 | if (l<0) { |
| 234 | if (errno!=EINTR && !iswouldblock(errno)) |
| 235 | fatal_perror("%s: userv_afterpoll: read(rxfd)", |
| 236 | st->slip.nl.name); |
| 237 | } else if (l==0) { |
| 238 | fatal("%s: userv_afterpoll: read(rxfd)=0; userv gone away?", |
| 239 | st->slip.nl.name); |
| 240 | } else slip_unstuff(&st->slip,rxbuf,l); |
| 241 | } |
| 242 | } |
| 243 | |
| 244 | /* Send buf to the kernel. Free buf before returning. */ |
| 245 | static void userv_deliver_to_kernel(void *sst, struct buffer_if *buf) |
| 246 | { |
| 247 | struct userv *st=sst; |
| 248 | |
| 249 | if (buf->size > st->slip.nl.mtu) { |
| 250 | Message(M_ERR,"%s: packet of size %"PRIu32" exceeds mtu %"PRIu32":" |
| 251 | " cannot be injected into kernel, dropped\n", |
| 252 | st->slip.nl.name, buf->size, st->slip.nl.mtu); |
| 253 | BUF_FREE(buf); |
| 254 | return; |
| 255 | } |
| 256 | |
| 257 | slip_stuff(&st->slip,buf,st->txfd); |
| 258 | } |
| 259 | |
| 260 | static void userv_userv_callback(void *sst, pid_t pid, int status) |
| 261 | { |
| 262 | struct userv *st=sst; |
| 263 | |
| 264 | if (pid!=st->pid) { |
| 265 | Message(M_WARNING,"userv_callback called unexpectedly with pid %d " |
| 266 | "(expected %d)\n",pid,st->pid); |
| 267 | return; |
| 268 | } |
| 269 | if (!(st->expecting_userv_exit && |
| 270 | (!status || |
| 271 | (WIFSIGNALED(status) && WTERMSIG(status)==SIGTERM)))) { |
| 272 | lg_exitstatus(0,st->slip.nl.name,0, |
| 273 | st->expecting_userv_exit ? M_WARNING : M_FATAL, |
| 274 | status,"userv"); |
| 275 | } |
| 276 | st->pid=0; |
| 277 | } |
| 278 | |
| 279 | struct userv_entry_rec { |
| 280 | cstring_t path; |
| 281 | const char **argv; |
| 282 | int in; |
| 283 | int out; |
| 284 | /* XXX perhaps we should collect and log stderr? */ |
| 285 | }; |
| 286 | |
| 287 | static void userv_entry(void *sst) |
| 288 | { |
| 289 | struct userv_entry_rec *st=sst; |
| 290 | |
| 291 | dup2(st->in,0); |
| 292 | dup2(st->out,1); |
| 293 | |
| 294 | setsid(); |
| 295 | execvp(st->path,(char *const*)st->argv); |
| 296 | perror("userv-entry: execvp()"); |
| 297 | exit(1); |
| 298 | } |
| 299 | |
| 300 | static void userv_invoke_userv(struct userv *st) |
| 301 | { |
| 302 | struct userv_entry_rec er[1]; |
| 303 | int c_stdin[2]; |
| 304 | int c_stdout[2]; |
| 305 | string_t nets; |
| 306 | string_t s; |
| 307 | struct netlink_client *r; |
| 308 | struct ipset *allnets; |
| 309 | struct subnet_list *snets; |
| 310 | int i, nread; |
| 311 | uint8_t confirm; |
| 312 | |
| 313 | if (st->pid) { |
| 314 | fatal("userv_invoke_userv: already running"); |
| 315 | } |
| 316 | |
| 317 | /* This is where we actually invoke userv - all the networks we'll |
| 318 | be using should already have been registered. */ |
| 319 | |
| 320 | char addrs[512]; |
| 321 | snprintf(addrs,sizeof(addrs),"%s,%s,%d,slip", |
| 322 | ipaddr_to_string(st->slip.nl.local_address), |
| 323 | ipaddr_to_string(st->slip.nl.secnet_address),st->slip.nl.mtu); |
| 324 | |
| 325 | allnets=ipset_new(); |
| 326 | for (r=st->slip.nl.clients; r; r=r->next) { |
| 327 | if (r->link_quality > LINK_QUALITY_UNUSED) { |
| 328 | struct ipset *nan; |
| 329 | r->kup=True; |
| 330 | nan=ipset_union(allnets,r->networks); |
| 331 | ipset_free(allnets); |
| 332 | allnets=nan; |
| 333 | } |
| 334 | } |
| 335 | snets=ipset_to_subnet_list(allnets); |
| 336 | ipset_free(allnets); |
| 337 | nets=safe_malloc(20*snets->entries,"userv_invoke_userv:nets"); |
| 338 | *nets=0; |
| 339 | for (i=0; i<snets->entries; i++) { |
| 340 | s=subnet_to_string(snets->list[i]); |
| 341 | strcat(nets,s); |
| 342 | strcat(nets,","); |
| 343 | } |
| 344 | nets[strlen(nets)-1]=0; |
| 345 | subnet_list_free(snets); |
| 346 | |
| 347 | Message(M_INFO,"%s: about to invoke: %s %s %s %s %s\n",st->slip.nl.name, |
| 348 | st->userv_path,st->service_user,st->service_name,addrs,nets); |
| 349 | |
| 350 | st->slip.pending_esc=False; |
| 351 | |
| 352 | /* Invoke userv */ |
| 353 | pipe_cloexec(c_stdin); |
| 354 | pipe_cloexec(c_stdout); |
| 355 | st->txfd=c_stdin[1]; |
| 356 | st->rxfd=c_stdout[0]; |
| 357 | |
| 358 | er->in=c_stdin[0]; |
| 359 | er->out=c_stdout[1]; |
| 360 | /* The arguments are: |
| 361 | userv |
| 362 | service-user |
| 363 | service-name |
| 364 | local-addr,secnet-addr,mtu,protocol |
| 365 | route1,route2,... */ |
| 366 | const char *er_argv[6]; |
| 367 | er->argv=er_argv; |
| 368 | er->argv[0]=st->userv_path; |
| 369 | er->argv[1]=st->service_user; |
| 370 | er->argv[2]=st->service_name; |
| 371 | er->argv[3]=addrs; |
| 372 | er->argv[4]=nets; |
| 373 | er->argv[5]=NULL; |
| 374 | er->path=st->userv_path; |
| 375 | |
| 376 | st->pid=makesubproc(userv_entry, userv_userv_callback, |
| 377 | er, st, st->slip.nl.name); |
| 378 | close(er->in); |
| 379 | close(er->out); |
| 380 | free(nets); |
| 381 | Message(M_INFO,"%s: userv-ipif pid is %d\n",st->slip.nl.name,st->pid); |
| 382 | /* Read a single character from the pipe to confirm userv-ipif is |
| 383 | running. If we get a SIGCHLD at this point then we'll get EINTR. */ |
| 384 | if ((nread=read(st->rxfd,&confirm,1))!=1) { |
| 385 | if (errno==EINTR) { |
| 386 | Message(M_WARNING,"%s: read of confirmation byte was " |
| 387 | "interrupted\n",st->slip.nl.name); |
| 388 | } else { |
| 389 | if (nread<0) { |
| 390 | fatal_perror("%s: error reading confirmation byte", |
| 391 | st->slip.nl.name); |
| 392 | } else { |
| 393 | fatal("%s: unexpected EOF instead of confirmation byte" |
| 394 | " - userv ipif failed?", st->slip.nl.name); |
| 395 | } |
| 396 | } |
| 397 | } else { |
| 398 | if (confirm!=SLIP_END) { |
| 399 | fatal("%s: bad confirmation byte %d from userv-ipif", |
| 400 | st->slip.nl.name,confirm); |
| 401 | } |
| 402 | } |
| 403 | setnonblock(st->txfd); |
| 404 | setnonblock(st->rxfd); |
| 405 | |
| 406 | add_hook(PHASE_CHILDPERSIST,childpersist_closefd_hook,&st->txfd); |
| 407 | add_hook(PHASE_CHILDPERSIST,childpersist_closefd_hook,&st->rxfd); |
| 408 | } |
| 409 | |
| 410 | static void userv_kill_userv(struct userv *st) |
| 411 | { |
| 412 | if (st->pid) { |
| 413 | kill(-st->pid,SIGTERM); |
| 414 | st->expecting_userv_exit=True; |
| 415 | } |
| 416 | } |
| 417 | |
| 418 | static void userv_phase_hook(void *sst, uint32_t newphase) |
| 419 | { |
| 420 | struct userv *st=sst; |
| 421 | /* We must wait until signal processing has started before forking |
| 422 | userv */ |
| 423 | if (newphase==PHASE_RUN) { |
| 424 | userv_invoke_userv(st); |
| 425 | /* Register for poll() */ |
| 426 | register_for_poll(st, userv_beforepoll, userv_afterpoll, |
| 427 | st->slip.nl.name); |
| 428 | } |
| 429 | if (newphase==PHASE_SHUTDOWN) { |
| 430 | userv_kill_userv(st); |
| 431 | } |
| 432 | } |
| 433 | |
| 434 | static list_t *userv_apply(closure_t *self, struct cloc loc, dict_t *context, |
| 435 | list_t *args) |
| 436 | { |
| 437 | struct userv *st; |
| 438 | item_t *item; |
| 439 | dict_t *dict; |
| 440 | |
| 441 | NEW(st); |
| 442 | |
| 443 | /* First parameter must be a dict */ |
| 444 | item=list_elem(args,0); |
| 445 | if (!item || item->type!=t_dict) |
| 446 | cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n"); |
| 447 | |
| 448 | dict=item->data.dict; |
| 449 | |
| 450 | slip_init(&st->slip,loc,dict,"netlink-userv-ipif", |
| 451 | userv_deliver_to_kernel); |
| 452 | |
| 453 | st->userv_path=dict_read_string(dict,"userv-path",False,"userv-netlink", |
| 454 | loc); |
| 455 | st->service_user=dict_read_string(dict,"service-user",False, |
| 456 | "userv-netlink",loc); |
| 457 | st->service_name=dict_read_string(dict,"service-name",False, |
| 458 | "userv-netlink",loc); |
| 459 | if (!st->userv_path) st->userv_path="userv"; |
| 460 | if (!st->service_user) st->service_user="root"; |
| 461 | if (!st->service_name) st->service_name="ipif"; |
| 462 | st->rxfd=-1; st->txfd=-1; |
| 463 | st->pid=0; |
| 464 | st->expecting_userv_exit=False; |
| 465 | add_hook(PHASE_RUN,userv_phase_hook,st); |
| 466 | add_hook(PHASE_SHUTDOWN,userv_phase_hook,st); |
| 467 | |
| 468 | return new_closure(&st->slip.nl.cl); |
| 469 | } |
| 470 | |
| 471 | void slip_module(dict_t *dict) |
| 472 | { |
| 473 | add_closure(dict,"userv-ipif",userv_apply); |
| 474 | } |