mdw@git.distorted.org.uk Git - secnet/blob - secnet.h

   1 /* Core interface of secnet, to be used by all modules */
   2
   3 #ifndef secnet_h
   4 #define secnet_h
   5
   6 #include "config.h"
   7 #include <stdlib.h>
   8 #include <stdarg.h>
   9 #include <stdio.h>
  10 #include <string.h>
  11 #include <assert.h>
  12 #include <fcntl.h>
  13 #include <unistd.h>
  14 #include <sys/poll.h>
  15 #include <sys/types.h>
  16 #include <sys/time.h>
  17 #include <netinet/in.h>
  18 #include <arpa/inet.h>
  19
  20 #define MAX_PEER_ADDRS 5
  21 /* send at most this many copies; honour at most that many addresses */
  22
  23 struct comm_if;
  24 struct comm_addr;
  25
  26 typedef char *string_t;
  27 typedef const char *cstring_t;
  28
  29 #define False (_Bool)0
  30 #define True  (_Bool)1
  31 typedef _Bool bool_t;
  32
  33 union iaddr {
  34     struct sockaddr sa;
  35     struct sockaddr_in sin;
  36 #ifdef CONFIG_IPV6
  37     struct sockaddr_in6 sin6;
  38 #endif
  39 };
  40
  41 #define ASSERT(x) do { if (!(x)) { fatal("assertion failed line %d file " \
  42                                          __FILE__,__LINE__); } } while(0)
  43
  44 /* from version.c */
  45
  46 extern char version[];
  47
  48 /* from logmsg.c */
  49 extern uint32_t message_level;
  50 extern bool_t secnet_is_daemon;
  51 extern struct log_if *system_log;
  52
  53 /* from process.c */
  54 extern void start_signal_handling(void);
  55
  56 /***** CONFIGURATION support *****/
  57
  58 extern bool_t just_check_config; /* If True then we're going to exit after
  59                                     reading the configuration file */
  60 extern bool_t background; /* If True then we'll eventually run as a daemon */
  61
  62 typedef struct dict dict_t;        /* Configuration dictionary */
  63 typedef struct closure closure_t;
  64 typedef struct item item_t;
  65 typedef struct list list_t;        /* A list of items */
  66
  67 /* Configuration file location, for error-reporting */
  68 struct cloc {
  69     cstring_t file;
  70     int line;
  71 };
  72
  73 /* Modules export closures, which can be invoked from the configuration file.
  74    "Invoking" a closure usually returns another closure (of a different
  75    type), but can actually return any configuration object. */
  76 typedef list_t *(apply_fn)(closure_t *self, struct cloc loc,
  77                            dict_t *context, list_t *data);
  78 struct closure {
  79     cstring_t description; /* For debugging */
  80     uint32_t type; /* Central registry... */
  81     apply_fn *apply;
  82     void *interface; /* Interface for use inside secnet; depends on type */
  83 };
  84
  85 enum types { t_null, t_bool, t_string, t_number, t_dict, t_closure };
  86 struct item {
  87     enum types type;
  88     union {
  89         bool_t bool;
  90         string_t string;
  91         uint32_t number;
  92         dict_t *dict;
  93         closure_t *closure;
  94     } data;
  95     struct cloc loc;
  96 };
  97
  98 /* Note that it is unwise to use this structure directly; use the list
  99    manipulation functions instead. */
 100 struct list {
 101     item_t *item;
 102     struct list *next;
 103 };
 104
 105 /* In the following two lookup functions, NULL means 'not found' */
 106 /* Lookup a value in the specified dictionary, or its parents */
 107 extern list_t *dict_lookup(dict_t *dict, cstring_t key);
 108 /* Lookup a value in just the specified dictionary */
 109 extern list_t *dict_lookup_primitive(dict_t *dict, cstring_t key);
 110 /* Add a value to the specified dictionary */
 111 extern void dict_add(dict_t *dict, cstring_t key, list_t *val);
 112 /* Obtain an array of keys in the dictionary. malloced; caller frees */
 113 extern cstring_t *dict_keys(dict_t *dict);
 114
 115 /* List-manipulation functions */
 116 extern list_t *list_new(void);
 117 extern int32_t list_length(const list_t *a);
 118 extern list_t *list_append(list_t *a, item_t *i);
 119 extern list_t *list_append_list(list_t *a, list_t *b);
 120 /* Returns an item from the list (index starts at 0), or NULL */
 121 extern item_t *list_elem(list_t *l, int32_t index);
 122
 123 /* Convenience functions */
 124 extern list_t *new_closure(closure_t *cl);
 125 extern void add_closure(dict_t *dict, cstring_t name, apply_fn apply);
 126 extern void *find_cl_if(dict_t *dict, cstring_t name, uint32_t type,
 127                         bool_t fail_if_invalid, cstring_t desc,
 128                         struct cloc loc);
 129 extern item_t *dict_find_item(dict_t *dict, cstring_t key, bool_t required,
 130                               cstring_t desc, struct cloc loc);
 131 extern string_t dict_read_string(dict_t *dict, cstring_t key, bool_t required,
 132                                  cstring_t desc, struct cloc loc);
 133 extern uint32_t dict_read_number(dict_t *dict, cstring_t key, bool_t required,
 134                                  cstring_t desc, struct cloc loc,
 135                                  uint32_t def);
 136   /* return value can safely be assigned to int32_t */
 137 extern bool_t dict_read_bool(dict_t *dict, cstring_t key, bool_t required,
 138                              cstring_t desc, struct cloc loc, bool_t def);
 139 struct flagstr {
 140     cstring_t name;
 141     uint32_t value;
 142 };
 143 extern uint32_t string_to_word(cstring_t s, struct cloc loc,
 144                                struct flagstr *f, cstring_t desc);
 145 extern uint32_t string_list_to_word(list_t *l, struct flagstr *f,
 146                                     cstring_t desc);
 147
 148 /***** END of configuration support *****/
 149
 150 /***** UTILITY functions *****/
 151
 152 extern char *safe_strdup(const char *string, const char *message);
 153 extern void *safe_malloc(size_t size, const char *message);
 154 extern void *safe_malloc_ary(size_t size, size_t count, const char *message);
 155
 156 void setcloexec(int fd); /* cannot fail */
 157 void pipe_cloexec(int fd[2]); /* pipe(), setcloexec() twice; cannot fail */
 158
 159 extern int sys_cmd(const char *file, const char *argc, ...);
 160
 161 extern uint64_t now_global;
 162 extern struct timeval tv_now_global;
 163
 164 static const uint64_t       *const now    = &now_global;
 165 static const struct timeval *const tv_now = &tv_now_global;
 166
 167 /* "now" is current program time, in milliseconds. It is derived
 168    from tv_now. Both are provided by the event loop. */
 169
 170 /***** END of utility functions *****/
 171
 172 /***** START of max_start_pad handling *****/
 173
 174 extern int32_t site_max_start_pad, transform_max_start_pad,
 175     comm_max_start_pad;
 176
 177 void update_max_start_pad(int32_t *our_module_global, int32_t our_instance);
 178 int32_t calculate_max_start_pad(void);
 179
 180 /***** END of max_start_pad handling *****/
 181
 182 /***** SCHEDULING support */
 183
 184 /* If nfds_io is insufficient for your needs, set it to the required
 185    number and return ERANGE. timeout is in milliseconds; if it is too
 186    high then lower it. It starts at -1 (==infinite) */
 187 typedef int beforepoll_fn(void *st, struct pollfd *fds, int *nfds_io,
 188                           int *timeout_io);
 189 typedef void afterpoll_fn(void *st, struct pollfd *fds, int nfds);
 190
 191 /* Register interest in the main loop of the program. Before a call
 192    to poll() your supplied beforepoll function will be called. After
 193    the call to poll() the supplied afterpoll function will be called.
 194    max_nfds is a _hint_ about the maximum number of struct pollfd
 195    structures you may require - you can always ask for more in
 196    *nfds_io. */
 197 extern void register_for_poll(void *st, beforepoll_fn *before,
 198                               afterpoll_fn *after, int32_t max_nfds,
 199                               cstring_t desc);
 200
 201 /***** END of scheduling support */
 202
 203 /***** PROGRAM LIFETIME support */
 204
 205 /* The secnet program goes through a number of phases in its lifetime.
 206    Module code may arrange to be called just as various phases are
 207    entered.
 208
 209    Remember to update the table in util.c if changing the set of
 210    phases. */
 211
 212 enum phase {
 213     PHASE_INIT,
 214     PHASE_GETOPTS,             /* Process command-line arguments */
 215     PHASE_READCONFIG,          /* Parse and process configuration file */
 216     PHASE_SETUP,               /* Process information in configuration */
 217     PHASE_DAEMONIZE,           /* Become a daemon (if necessary) */
 218     PHASE_GETRESOURCES,        /* Obtain all external resources */
 219     PHASE_DROPPRIV,            /* Last chance for privileged operations */
 220     PHASE_RUN,
 221     PHASE_SHUTDOWN,            /* About to die; delete key material, etc. */
 222     /* Keep this last: */
 223     NR_PHASES,
 224 };
 225
 226 typedef void hook_fn(void *self, uint32_t newphase);
 227 bool_t add_hook(uint32_t phase, hook_fn *f, void *state);
 228 bool_t remove_hook(uint32_t phase, hook_fn *f, void *state);
 229
 230 extern uint32_t current_phase;
 231 extern void enter_phase(uint32_t new_phase);
 232
 233 /* Some features (like netlink 'soft' routes) require that secnet
 234    retain root privileges.  They should indicate that here when
 235    appropriate. */
 236 extern bool_t require_root_privileges;
 237 extern cstring_t require_root_privileges_explanation;
 238
 239 /***** END of program lifetime support *****/
 240
 241 /***** MODULE support *****/
 242
 243 /* Module initialisation function type - modules export one function of
 244    this type which is called to initialise them. For dynamically loaded
 245    modules it's called "secnet_module". */
 246 typedef void init_module(dict_t *dict);
 247
 248 extern void init_builtin_modules(dict_t *dict);
 249
 250 extern init_module resolver_module;
 251 extern init_module random_module;
 252 extern init_module udp_module;
 253 extern init_module util_module;
 254 extern init_module site_module;
 255 extern init_module transform_eax_module;
 256 extern init_module transform_cbcmac_module;
 257 extern init_module netlink_module;
 258 extern init_module rsa_module;
 259 extern init_module dh_module;
 260 extern init_module md5_module;
 261 extern init_module slip_module;
 262 extern init_module tun_module;
 263 extern init_module sha1_module;
 264 extern init_module log_module;
 265
 266 /***** END of module support *****/
 267
 268 /***** CLOSURE TYPES and interface definitions *****/
 269
 270 #define CL_PURE         0
 271 #define CL_RESOLVER     1
 272 #define CL_RANDOMSRC    2
 273 #define CL_RSAPUBKEY    3
 274 #define CL_RSAPRIVKEY   4
 275 #define CL_COMM         5
 276 #define CL_IPIF         6
 277 #define CL_LOG          7
 278 #define CL_SITE         8
 279 #define CL_TRANSFORM    9
 280 #define CL_DH          11
 281 #define CL_HASH        12
 282 #define CL_BUFFER      13
 283 #define CL_NETLINK     14
 284
 285 struct buffer_if;
 286
 287 /* PURE closure requires no interface */
 288
 289 /* RESOLVER interface */
 290
 291 /* Answers to queries are delivered to a function of this
 292    type. 'address' will be NULL if there was a problem with the query. It
 293    will be freed once resolve_answer_fn returns.  naddrs is the actual
 294    size of the array at addrs; was_naddrs is the number of addresses
 295    actually found in the DNS, which may be bigger if addrs is equal
 296    to MAX_PEER_ADDRS (ie there were too many). */
 297 typedef void resolve_answer_fn(void *st, const struct comm_addr *addrs,
 298                                int naddrs, int was_naddrs);
 299 typedef bool_t resolve_request_fn(void *st, cstring_t name,
 300                                   int remoteport, struct comm_if *comm,
 301                                   resolve_answer_fn *cb, void *cst);
 302 struct resolver_if {
 303     void *st;
 304     resolve_request_fn *request;
 305 };
 306
 307 /* RANDOMSRC interface */
 308
 309 /* Return some random data. Returns TRUE for success. */
 310 typedef bool_t random_fn(void *st, int32_t bytes, uint8_t *buff);
 311
 312 struct random_if {
 313     void *st;
 314     bool_t blocking;
 315     random_fn *generate;
 316 };
 317
 318 /* RSAPUBKEY interface */
 319
 320 typedef bool_t rsa_checksig_fn(void *st, uint8_t *data, int32_t datalen,
 321                                cstring_t signature);
 322 struct rsapubkey_if {
 323     void *st;
 324     rsa_checksig_fn *check;
 325 };
 326
 327 /* RSAPRIVKEY interface */
 328
 329 typedef string_t rsa_makesig_fn(void *st, uint8_t *data, int32_t datalen);
 330 struct rsaprivkey_if {
 331     void *st;
 332     rsa_makesig_fn *sign;
 333 };
 334
 335 /* COMM interface */
 336
 337 struct comm_addr {
 338     /* This struct is pure data; in particular comm's clients may
 339        freely copy it. */
 340     struct comm_if *comm;
 341     union iaddr ia;
 342 };
 343
 344 /* Return True if the packet was processed, and shouldn't be passed to
 345    any other potential receivers. */
 346 typedef bool_t comm_notify_fn(void *state, struct buffer_if *buf,
 347                               const struct comm_addr *source);
 348 typedef void comm_request_notify_fn(void *commst, void *nst,
 349                                     comm_notify_fn *fn);
 350 typedef void comm_release_notify_fn(void *commst, void *nst,
 351                                     comm_notify_fn *fn);
 352 typedef bool_t comm_sendmsg_fn(void *commst, struct buffer_if *buf,
 353                                const struct comm_addr *dest);
 354   /* Only returns false if (we know that) the local network
 355    * environment is such that this address cannot work; transient
 356    * or unknown/unexpected failures return true. */
 357 typedef const char *comm_addr_to_string_fn(void *commst,
 358                                            const struct comm_addr *ca);
 359         /* Returned string is in a static buffer. */
 360 struct comm_if {
 361     void *st;
 362     comm_request_notify_fn *request_notify;
 363     comm_release_notify_fn *release_notify;
 364     comm_sendmsg_fn *sendmsg;
 365     comm_addr_to_string_fn *addr_to_string;
 366 };
 367
 368 bool_t iaddr_equal(const union iaddr *ia, const union iaddr *ib);
 369
 370 static inline const char *comm_addr_to_string(const struct comm_addr *ca)
 371 {
 372     return ca->comm->addr_to_string(ca->comm->st, ca);
 373 }
 374
 375 static inline bool_t comm_addr_equal(const struct comm_addr *a,
 376                                      const struct comm_addr *b)
 377 {
 378     return a->comm==b->comm && iaddr_equal(&a->ia,&b->ia);
 379 }
 380
 381 /* LOG interface */
 382
 383 #define LOG_MESSAGE_BUFLEN 1023
 384
 385 typedef void log_msg_fn(void *st, int class, const char *message, ...);
 386 typedef void log_vmsg_fn(void *st, int class, const char *message,
 387                          va_list args);
 388 struct log_if {
 389     void *st;
 390     log_vmsg_fn *vlogfn; /* printf format checking.  Use [v]slilog instead */
 391     char buff[LOG_MESSAGE_BUFLEN+1];
 392 };
 393 /* (convenience functions, defined in util.c) */
 394 extern void slilog(struct log_if *lf, int class, const char *message, ...)
 395 FORMAT(printf,3,4);
 396 extern void vslilog(struct log_if *lf, int class, const char *message, va_list)
 397 FORMAT(printf,3,0);
 398
 399 /* Versions which take (parts of) (multiple) messages, using \n to
 400  * distinguish one message from another. */
 401 extern void slilog_part(struct log_if *lf, int class, const char *message, ...)
 402 FORMAT(printf,3,4);
 403 extern void vslilog_part(struct log_if *lf, int class, const char *message,
 404                          va_list) FORMAT(printf,3,0);
 405
 406 /* SITE interface */
 407
 408 /* Pretty much a placeholder; allows starting and stopping of processing,
 409    key expiry, etc. */
 410 typedef void site_control_fn(void *st, bool_t run);
 411 typedef uint32_t site_status_fn(void *st);
 412 struct site_if {
 413     void *st;
 414     site_control_fn *control;
 415     site_status_fn *status;
 416 };
 417
 418 /* TRANSFORM interface */
 419
 420 /* A reversable transformation. Transforms buffer in-place; may add
 421    data to start or end. (Reverse transformations decrease
 422    length, of course.)  Transformations may be key-dependent, in which
 423    case key material is passed in at initialisation time. They may
 424    also depend on internal factors (eg. time) and keep internal
 425    state. A struct transform_if only represents a particular type of
 426    transformation; instances of the transformation (eg. with
 427    particular key material) have a different C type. The same
 428    secret key will be used in opposite directions between a pair of
 429    secnets; one of these pairs will get direction==False, the other True. */
 430
 431 typedef struct transform_inst_if *transform_createinstance_fn(void *st);
 432 typedef bool_t transform_setkey_fn(void *st, uint8_t *key, int32_t keylen,
 433                                    bool_t direction);
 434 typedef bool_t transform_valid_fn(void *st); /* 0: no key; 1: ok */
 435 typedef void transform_delkey_fn(void *st);
 436 typedef void transform_destroyinstance_fn(void *st);
 437 /* Returns:
 438  *   0: all is well
 439  *   1: for any other problem
 440  *   2: message decrypted but sequence number was out of range
 441  */
 442 typedef uint32_t transform_apply_fn(void *st, struct buffer_if *buf,
 443                                     const char **errmsg);
 444
 445 struct transform_inst_if {
 446     void *st;
 447     transform_setkey_fn *setkey;
 448     transform_valid_fn *valid;
 449     transform_delkey_fn *delkey;
 450     transform_apply_fn *forwards;
 451     transform_apply_fn *reverse;
 452     transform_destroyinstance_fn *destroy;
 453 };
 454
 455 struct transform_if {
 456     void *st;
 457     int capab_transformnum;
 458     int32_t keylen; /* <<< INT_MAX */
 459     transform_createinstance_fn *create;
 460 };
 461
 462 /* NETLINK interface */
 463
 464 /* Used by netlink to deliver to site, and by site to deliver to
 465    netlink.  cid is the client identifier returned by
 466    netlink_regnets_fn.  If buf has size 0 then the function is just
 467    being called for its site-effects (eg. making the site code attempt
 468    to bring up a network link) */
 469 typedef void netlink_deliver_fn(void *st, struct buffer_if *buf);
 470 /* site code can tell netlink when outgoing packets will be dropped,
 471    so netlink can generate appropriate ICMP and make routing decisions */
 472 #define LINK_QUALITY_UNUSED 0   /* This link is unused, do not make this netlink */
 473 #define LINK_QUALITY_DOWN 1   /* No chance of a packet being delivered right away*/
 474 #define LINK_QUALITY_DOWN_STALE_ADDRESS 2 /* Link down, old address information */
 475 #define LINK_QUALITY_DOWN_CURRENT_ADDRESS 3 /* Link down, current address information */
 476 #define LINK_QUALITY_UP 4     /* Link active */
 477 #define MAXIMUM_LINK_QUALITY 3
 478 typedef void netlink_link_quality_fn(void *st, uint32_t quality);
 479 typedef void netlink_register_fn(void *st, netlink_deliver_fn *deliver,
 480                                  void *dst, uint32_t *localmtu_r /* NULL ok */);
 481 typedef void netlink_output_config_fn(void *st, struct buffer_if *buf);
 482 typedef bool_t netlink_check_config_fn(void *st, struct buffer_if *buf);
 483 typedef void netlink_set_mtu_fn(void *st, int32_t new_mtu);
 484 struct netlink_if {
 485     void *st;
 486     netlink_register_fn *reg;
 487     netlink_deliver_fn *deliver;
 488     netlink_link_quality_fn *set_quality;
 489     netlink_set_mtu_fn *set_mtu;
 490 };
 491
 492 /* DH interface */
 493
 494 /* Returns public key as a malloced hex string */
 495 typedef string_t dh_makepublic_fn(void *st, uint8_t *secret,
 496                                   int32_t secretlen);
 497 /* Fills buffer (up to buflen) with shared secret */
 498 typedef void dh_makeshared_fn(void *st, uint8_t *secret,
 499                               int32_t secretlen, cstring_t rempublic,
 500                               uint8_t *sharedsecret, int32_t buflen);
 501 struct dh_if {
 502     void *st;
 503     int32_t len; /* Approximate size of modulus in bytes */
 504     int32_t ceil_len; /* Number of bytes just sufficient to contain modulus */
 505     dh_makepublic_fn *makepublic;
 506     dh_makeshared_fn *makeshared;
 507 };
 508
 509 /* HASH interface */
 510
 511 typedef void *hash_init_fn(void);
 512 typedef void hash_update_fn(void *st, const void *buf, int32_t len);
 513 typedef void hash_final_fn(void *st, uint8_t *digest);
 514 struct hash_if {
 515     int32_t len; /* Hash output length in bytes */
 516     hash_init_fn *init;
 517     hash_update_fn *update;
 518     hash_final_fn *final;
 519 };
 520
 521 /* BUFFER interface */
 522
 523 struct buffer_if {
 524     bool_t free;
 525     cstring_t owner; /* Set to constant string */
 526     uint32_t flags; /* How paranoid should we be? */
 527     struct cloc loc; /* Where we were defined */
 528     uint8_t *base;
 529     uint8_t *start;
 530     int32_t size; /* Size of buffer contents */
 531     int32_t alloclen; /* Total length allocated at base */
 532 };
 533
 534 /***** LOG functions *****/
 535
 536 #define M_DEBUG_CONFIG 0x001
 537 #define M_DEBUG_PHASE  0x002
 538 #define M_DEBUG        0x004
 539 #define M_INFO         0x008
 540 #define M_NOTICE       0x010
 541 #define M_WARNING      0x020
 542 #define M_ERR          0x040
 543 #define M_SECURITY     0x080
 544 #define M_FATAL        0x100
 545
 546 /* The fatal() family of functions require messages that do not end in '\n' */
 547 extern NORETURN(fatal(const char *message, ...)) FORMAT(printf,1,2);
 548 extern NORETURN(fatal_perror(const char *message, ...)) FORMAT(printf,1,2);
 549 extern NORETURN(fatal_status(int status, const char *message, ...))
 550        FORMAT(printf,2,3);
 551 extern NORETURN(fatal_perror_status(int status, const char *message, ...))
 552        FORMAT(printf,2,3);
 553
 554 /* The cfgfatal() family of functions require messages that end in '\n' */
 555 extern NORETURN(cfgfatal(struct cloc loc, cstring_t facility,
 556                          const char *message, ...)) FORMAT(printf,3,4);
 557 extern void cfgfile_postreadcheck(struct cloc loc, FILE *f);
 558 extern NORETURN(vcfgfatal_maybefile(FILE *maybe_f, struct cloc loc,
 559                                     cstring_t facility, const char *message,
 560                                     va_list))
 561     FORMAT(printf,4,0);
 562 extern NORETURN(cfgfatal_maybefile(FILE *maybe_f, struct cloc loc,
 563                                    cstring_t facility,
 564                                    const char *message, ...))
 565     FORMAT(printf,4,5);
 566
 567 extern void Message(uint32_t class, const char *message, ...)
 568     FORMAT(printf,2,3);
 569 extern void log_from_fd(int fd, cstring_t prefix, struct log_if *log);
 570
 571 /***** END of log functions *****/
 572
 573 #define STRING2(x) #x
 574 #define STRING(x) STRING2(x)
 575
 576 #define FILLZERO(obj) (memset(&(obj),0,sizeof((obj))))
 577
 578 /*
 579  * void COPY_OBJ(  OBJECT& dst, const OBJECT& src);
 580  * void COPY_ARRAY(OBJECT *dst, const OBJECT *src, INTEGER count);
 581  *   // Typesafe: we check that the type OBJECT is the same in both cases.
 582  *   // It is OK to use COPY_OBJ on an array object, provided it's
 583  *   // _actually_ the whole array object and not decayed into a
 584  *   // pointer (e.g. a formal parameter).
 585  */
 586 #define COPY_OBJ(dst,src) \
 587     (&(dst)==&(src), memcpy(&(dst),&(src),sizeof((dst))))
 588 #define COPY_ARRAY(dst,src,count) \
 589     (&(dst)[0]==&(src)[0], memcpy((dst),(src),sizeof((dst)[0])*(count)))
 590
 591 #endif /* secnet_h */