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     /* Everyone is also guaranteed that all padding is set to zero, ie
 338        that comm_addrs referring to semantically identical peers will
 339        compare equal with memcmp.  Anyone who constructs a comm_addr
 340        must start by memsetting it with FILLZERO, or some
 341        equivalent. */
 342     struct comm_if *comm;
 343     union iaddr ia;
 344 };
 345
 346 /* Return True if the packet was processed, and shouldn't be passed to
 347    any other potential receivers. */
 348 typedef bool_t comm_notify_fn(void *state, struct buffer_if *buf,
 349                               const struct comm_addr *source);
 350 typedef void comm_request_notify_fn(void *commst, void *nst,
 351                                     comm_notify_fn *fn);
 352 typedef void comm_release_notify_fn(void *commst, void *nst,
 353                                     comm_notify_fn *fn);
 354 typedef bool_t comm_sendmsg_fn(void *commst, struct buffer_if *buf,
 355                                const struct comm_addr *dest);
 356   /* Only returns false if (we know that) the local network
 357    * environment is such that this address cannot work; transient
 358    * or unknown/unexpected failures return true. */
 359 typedef const char *comm_addr_to_string_fn(void *commst,
 360                                            const struct comm_addr *ca);
 361         /* Returned string is in a static buffer. */
 362 struct comm_if {
 363     void *st;
 364     comm_request_notify_fn *request_notify;
 365     comm_release_notify_fn *release_notify;
 366     comm_sendmsg_fn *sendmsg;
 367     comm_addr_to_string_fn *addr_to_string;
 368 };
 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 /* LOG interface */
 376
 377 #define LOG_MESSAGE_BUFLEN 1023
 378
 379 typedef void log_msg_fn(void *st, int class, const char *message, ...);
 380 typedef void log_vmsg_fn(void *st, int class, const char *message,
 381                          va_list args);
 382 struct log_if {
 383     void *st;
 384     log_vmsg_fn *vlogfn; /* printf format checking.  Use [v]slilog instead */
 385     char buff[LOG_MESSAGE_BUFLEN+1];
 386 };
 387 /* (convenience functions, defined in util.c) */
 388 extern void slilog(struct log_if *lf, int class, const char *message, ...)
 389 FORMAT(printf,3,4);
 390 extern void vslilog(struct log_if *lf, int class, const char *message, va_list)
 391 FORMAT(printf,3,0);
 392
 393 /* Versions which take (parts of) (multiple) messages, using \n to
 394  * distinguish one message from another. */
 395 extern void slilog_part(struct log_if *lf, int class, const char *message, ...)
 396 FORMAT(printf,3,4);
 397 extern void vslilog_part(struct log_if *lf, int class, const char *message,
 398                          va_list) FORMAT(printf,3,0);
 399
 400 /* SITE interface */
 401
 402 /* Pretty much a placeholder; allows starting and stopping of processing,
 403    key expiry, etc. */
 404 typedef void site_control_fn(void *st, bool_t run);
 405 typedef uint32_t site_status_fn(void *st);
 406 struct site_if {
 407     void *st;
 408     site_control_fn *control;
 409     site_status_fn *status;
 410 };
 411
 412 /* TRANSFORM interface */
 413
 414 /* A reversable transformation. Transforms buffer in-place; may add
 415    data to start or end. (Reverse transformations decrease
 416    length, of course.)  Transformations may be key-dependent, in which
 417    case key material is passed in at initialisation time. They may
 418    also depend on internal factors (eg. time) and keep internal
 419    state. A struct transform_if only represents a particular type of
 420    transformation; instances of the transformation (eg. with
 421    particular key material) have a different C type. The same
 422    secret key will be used in opposite directions between a pair of
 423    secnets; one of these pairs will get direction==False, the other True. */
 424
 425 typedef struct transform_inst_if *transform_createinstance_fn(void *st);
 426 typedef bool_t transform_setkey_fn(void *st, uint8_t *key, int32_t keylen,
 427                                    bool_t direction);
 428 typedef bool_t transform_valid_fn(void *st); /* 0: no key; 1: ok */
 429 typedef void transform_delkey_fn(void *st);
 430 typedef void transform_destroyinstance_fn(void *st);
 431 /* Returns:
 432  *   0: all is well
 433  *   1: for any other problem
 434  *   2: message decrypted but sequence number was out of range
 435  */
 436 typedef uint32_t transform_apply_fn(void *st, struct buffer_if *buf,
 437                                     const char **errmsg);
 438
 439 struct transform_inst_if {
 440     void *st;
 441     transform_setkey_fn *setkey;
 442     transform_valid_fn *valid;
 443     transform_delkey_fn *delkey;
 444     transform_apply_fn *forwards;
 445     transform_apply_fn *reverse;
 446     transform_destroyinstance_fn *destroy;
 447 };
 448
 449 struct transform_if {
 450     void *st;
 451     int capab_transformnum;
 452     int32_t keylen; /* <<< INT_MAX */
 453     transform_createinstance_fn *create;
 454 };
 455
 456 /* NETLINK interface */
 457
 458 /* Used by netlink to deliver to site, and by site to deliver to
 459    netlink.  cid is the client identifier returned by
 460    netlink_regnets_fn.  If buf has size 0 then the function is just
 461    being called for its site-effects (eg. making the site code attempt
 462    to bring up a network link) */
 463 typedef void netlink_deliver_fn(void *st, struct buffer_if *buf);
 464 /* site code can tell netlink when outgoing packets will be dropped,
 465    so netlink can generate appropriate ICMP and make routing decisions */
 466 #define LINK_QUALITY_UNUSED 0   /* This link is unused, do not make this netlink */
 467 #define LINK_QUALITY_DOWN 1   /* No chance of a packet being delivered right away*/
 468 #define LINK_QUALITY_DOWN_STALE_ADDRESS 2 /* Link down, old address information */
 469 #define LINK_QUALITY_DOWN_CURRENT_ADDRESS 3 /* Link down, current address information */
 470 #define LINK_QUALITY_UP 4     /* Link active */
 471 #define MAXIMUM_LINK_QUALITY 3
 472 typedef void netlink_link_quality_fn(void *st, uint32_t quality);
 473 typedef void netlink_register_fn(void *st, netlink_deliver_fn *deliver,
 474                                  void *dst, uint32_t *localmtu_r /* NULL ok */);
 475 typedef void netlink_output_config_fn(void *st, struct buffer_if *buf);
 476 typedef bool_t netlink_check_config_fn(void *st, struct buffer_if *buf);
 477 typedef void netlink_set_mtu_fn(void *st, int32_t new_mtu);
 478 struct netlink_if {
 479     void *st;
 480     netlink_register_fn *reg;
 481     netlink_deliver_fn *deliver;
 482     netlink_link_quality_fn *set_quality;
 483     netlink_set_mtu_fn *set_mtu;
 484 };
 485
 486 /* DH interface */
 487
 488 /* Returns public key as a malloced hex string */
 489 typedef string_t dh_makepublic_fn(void *st, uint8_t *secret,
 490                                   int32_t secretlen);
 491 /* Fills buffer (up to buflen) with shared secret */
 492 typedef void dh_makeshared_fn(void *st, uint8_t *secret,
 493                               int32_t secretlen, cstring_t rempublic,
 494                               uint8_t *sharedsecret, int32_t buflen);
 495 struct dh_if {
 496     void *st;
 497     int32_t len; /* Approximate size of modulus in bytes */
 498     int32_t ceil_len; /* Number of bytes just sufficient to contain modulus */
 499     dh_makepublic_fn *makepublic;
 500     dh_makeshared_fn *makeshared;
 501 };
 502
 503 /* HASH interface */
 504
 505 typedef void *hash_init_fn(void);
 506 typedef void hash_update_fn(void *st, const void *buf, int32_t len);
 507 typedef void hash_final_fn(void *st, uint8_t *digest);
 508 struct hash_if {
 509     int32_t len; /* Hash output length in bytes */
 510     hash_init_fn *init;
 511     hash_update_fn *update;
 512     hash_final_fn *final;
 513 };
 514
 515 /* BUFFER interface */
 516
 517 struct buffer_if {
 518     bool_t free;
 519     cstring_t owner; /* Set to constant string */
 520     uint32_t flags; /* How paranoid should we be? */
 521     struct cloc loc; /* Where we were defined */
 522     uint8_t *base;
 523     uint8_t *start;
 524     int32_t size; /* Size of buffer contents */
 525     int32_t alloclen; /* Total length allocated at base */
 526 };
 527
 528 /***** LOG functions *****/
 529
 530 #define M_DEBUG_CONFIG 0x001
 531 #define M_DEBUG_PHASE  0x002
 532 #define M_DEBUG        0x004
 533 #define M_INFO         0x008
 534 #define M_NOTICE       0x010
 535 #define M_WARNING      0x020
 536 #define M_ERR          0x040
 537 #define M_SECURITY     0x080
 538 #define M_FATAL        0x100
 539
 540 /* The fatal() family of functions require messages that do not end in '\n' */
 541 extern NORETURN(fatal(const char *message, ...)) FORMAT(printf,1,2);
 542 extern NORETURN(fatal_perror(const char *message, ...)) FORMAT(printf,1,2);
 543 extern NORETURN(fatal_status(int status, const char *message, ...))
 544        FORMAT(printf,2,3);
 545 extern NORETURN(fatal_perror_status(int status, const char *message, ...))
 546        FORMAT(printf,2,3);
 547
 548 /* The cfgfatal() family of functions require messages that end in '\n' */
 549 extern NORETURN(cfgfatal(struct cloc loc, cstring_t facility,
 550                          const char *message, ...)) FORMAT(printf,3,4);
 551 extern void cfgfile_postreadcheck(struct cloc loc, FILE *f);
 552 extern NORETURN(vcfgfatal_maybefile(FILE *maybe_f, struct cloc loc,
 553                                     cstring_t facility, const char *message,
 554                                     va_list))
 555     FORMAT(printf,4,0);
 556 extern NORETURN(cfgfatal_maybefile(FILE *maybe_f, struct cloc loc,
 557                                    cstring_t facility,
 558                                    const char *message, ...))
 559     FORMAT(printf,4,5);
 560
 561 extern void Message(uint32_t class, const char *message, ...)
 562     FORMAT(printf,2,3);
 563 extern void log_from_fd(int fd, cstring_t prefix, struct log_if *log);
 564
 565 /***** END of log functions *****/
 566
 567 #define STRING2(x) #x
 568 #define STRING(x) STRING2(x)
 569
 570 #define FILLZERO(obj) (memset(&(obj),0,sizeof((obj))))
 571
 572 /*
 573  * void COPY_OBJ(  OBJECT& dst, const OBJECT& src);
 574  * void COPY_ARRAY(OBJECT *dst, const OBJECT *src, INTEGER count);
 575  *   // Typesafe: we check that the type OBJECT is the same in both cases.
 576  *   // It is OK to use COPY_OBJ on an array object, provided it's
 577  *   // _actually_ the whole array object and not decayed into a
 578  *   // pointer (e.g. a formal parameter).
 579  */
 580 #define COPY_OBJ(dst,src) \
 581     (&(dst)==&(src), memcpy(&(dst),&(src),sizeof((dst))))
 582 #define COPY_ARRAY(dst,src,count) \
 583     (&(dst)[0]==&(src)[0], memcpy((dst),(src),sizeof((dst)[0])*(count)))
 584
 585 #endif /* secnet_h */