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