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