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-rw-r--r--src/or/policies.c661
1 files changed, 661 insertions, 0 deletions
diff --git a/src/or/policies.c b/src/or/policies.c
new file mode 100644
index 000000000..dba6f2678
--- /dev/null
+++ b/src/or/policies.c
@@ -0,0 +1,661 @@
+/* Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. */
+/* See LICENSE for licensing information */
+/* $Id$ */
+const char policies_c_id[] = \
+ "$Id$";
+
+/**
+ * \file policies.c
+ * \brief Code to parse and use address policies and exit policies.
+ **/
+
+#include "or.h"
+
+static int expand_exit_policy_aliases(smartlist_t *entries, int assume_action);
+
+static addr_policy_t *socks_policy = NULL;
+static addr_policy_t *dir_policy = NULL;
+static addr_policy_t *authdir_reject_policy = NULL;
+static addr_policy_t *authdir_invalid_policy = NULL;
+
+/** Parsed addr_policy_t describing which addresses we believe we can start
+ * circuits at. */
+static addr_policy_t *reachable_or_addr_policy = NULL;
+/** Parsed addr_policy_t describing which addresses we believe we can connect
+ * to directories at. */
+static addr_policy_t *reachable_dir_addr_policy = NULL;
+
+/**
+ * Given a linked list of config lines containing "allow" and "deny"
+ * tokens, parse them and append the result to <b>dest</b>. Return -1
+ * if any tokens are malformed, else return 0.
+ */
+static int
+parse_addr_policy(config_line_t *cfg, addr_policy_t **dest,
+ int assume_action)
+{
+ addr_policy_t **nextp;
+ smartlist_t *entries;
+ int r = 0;
+
+ if (!cfg)
+ return 0;
+
+ nextp = dest;
+
+ while (*nextp)
+ nextp = &((*nextp)->next);
+
+ entries = smartlist_create();
+ for (; cfg; cfg = cfg->next) {
+ smartlist_split_string(entries, cfg->value, ",",
+ SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+ if (expand_exit_policy_aliases(entries,assume_action)<0) {
+ r = -1;
+ continue;
+ }
+ SMARTLIST_FOREACH(entries, const char *, ent,
+ {
+ log_debug(LD_CONFIG,"Adding new entry '%s'",ent);
+ *nextp = router_parse_addr_policy_from_string(ent, assume_action);
+ if (*nextp) {
+ if (addr_mask_get_bits((*nextp)->msk)<0) {
+ log_warn(LD_CONFIG, "Address policy element '%s' can't be expressed "
+ "as a bit prefix.", ent);
+ }
+ /* Advance nextp to the end of the policy. */
+ while (*nextp)
+ nextp = &((*nextp)->next);
+ } else {
+ log_warn(LD_CONFIG,"Malformed policy '%s'.", ent);
+ r = -1;
+ }
+ });
+ SMARTLIST_FOREACH(entries, char *, ent, tor_free(ent));
+ smartlist_clear(entries);
+ }
+ smartlist_free(entries);
+ return r;
+}
+
+/** Helper: parse the Reachable(Dir|OR)?Addresses fields into
+ * reachable_(or|dir)_addr_policy. */
+static void
+parse_reachable_addresses(void)
+{
+ or_options_t *options = get_options();
+
+ if (options->ReachableDirAddresses &&
+ options->ReachableORAddresses &&
+ options->ReachableAddresses) {
+ log_warn(LD_CONFIG,
+ "Both ReachableDirAddresses and ReachableORAddresses are set. "
+ "ReachableAddresses setting will be ignored.");
+ }
+ addr_policy_free(reachable_or_addr_policy);
+ reachable_or_addr_policy = NULL;
+ if (!options->ReachableORAddresses && options->ReachableAddresses)
+ log_info(LD_CONFIG,
+ "Using ReachableAddresses as ReachableORAddresses.");
+ if (parse_addr_policy(options->ReachableORAddresses ?
+ options->ReachableORAddresses :
+ options->ReachableAddresses,
+ &reachable_or_addr_policy, ADDR_POLICY_ACCEPT)) {
+ log_warn(LD_CONFIG,
+ "Error parsing Reachable%sAddresses entry; ignoring.",
+ options->ReachableORAddresses ? "OR" : "");
+ }
+
+ addr_policy_free(reachable_dir_addr_policy);
+ reachable_dir_addr_policy = NULL;
+ if (!options->ReachableDirAddresses && options->ReachableAddresses)
+ log_info(LD_CONFIG,
+ "Using ReachableAddresses as ReachableDirAddresses");
+ if (parse_addr_policy(options->ReachableDirAddresses ?
+ options->ReachableDirAddresses :
+ options->ReachableAddresses,
+ &reachable_dir_addr_policy, ADDR_POLICY_ACCEPT)) {
+ if (options->ReachableDirAddresses)
+ log_warn(LD_CONFIG,
+ "Error parsing ReachableDirAddresses entry; ignoring.");
+ }
+}
+
+/** Return true iff the firewall options might block any address:port
+ * combination.
+ */
+int
+firewall_is_fascist_or(void)
+{
+ return !!reachable_or_addr_policy;
+}
+
+/** Return true iff <b>policy</b> (possibly NULL) will allow a
+ * connection to <b>addr</b>:<b>port</b>.
+ */
+static int
+addr_policy_permits_address(uint32_t addr, uint16_t port,
+ addr_policy_t *policy)
+{
+ addr_policy_result_t p;
+ p = compare_addr_to_addr_policy(addr, port, policy);
+ switch (p) {
+ case ADDR_POLICY_PROBABLY_ACCEPTED:
+ case ADDR_POLICY_ACCEPTED:
+ return 1;
+ case ADDR_POLICY_PROBABLY_REJECTED:
+ case ADDR_POLICY_REJECTED:
+ return 0;
+ default:
+ log_warn(LD_BUG, "Unexpected result: %d", (int)p);
+ return 0;
+ }
+}
+
+int
+fascist_firewall_allows_address_or(uint32_t addr, uint16_t port)
+{
+ return addr_policy_permits_address(addr, port,
+ reachable_or_addr_policy);
+}
+
+int
+fascist_firewall_allows_address_dir(uint32_t addr, uint16_t port)
+{
+ return addr_policy_permits_address(addr, port,
+ reachable_dir_addr_policy);
+}
+
+/** Return 1 if <b>addr</b> is permitted to connect to our dir port,
+ * based on <b>dir_policy</b>. Else return 0.
+ */
+int
+dir_policy_permits_address(uint32_t addr)
+{
+ return addr_policy_permits_address(addr, 1, dir_policy);
+}
+
+/** Return 1 if <b>addr</b> is permitted to connect to our socks port,
+ * based on <b>socks_policy</b>. Else return 0.
+ */
+int
+socks_policy_permits_address(uint32_t addr)
+{
+ return addr_policy_permits_address(addr, 1, socks_policy);
+}
+
+/** Return 1 if <b>addr</b>:<b>port</b> is permitted to publish to our
+ * directory, based on <b>authdir_reject_policy</b>. Else return 0.
+ */
+int
+authdir_policy_permits_address(uint32_t addr, uint16_t port)
+{
+ return addr_policy_permits_address(addr, port, authdir_reject_policy);
+}
+
+/** Return 1 if <b>addr</b>:<b>port</b> is considered valid in our
+ * directory, based on <b>authdir_invalid_policy</b>. Else return 0.
+ */
+int
+authdir_policy_valid_address(uint32_t addr, uint16_t port)
+{
+ return addr_policy_permits_address(addr, port, authdir_invalid_policy);
+}
+
+#define REJECT(arg) \
+ do { *msg = tor_strdup(arg); goto err; } while (0)
+int
+validate_addr_policies(or_options_t *options, char **msg)
+{
+ addr_policy_t *addr_policy=NULL;
+ *msg = NULL;
+
+ if (policies_parse_exit_policy(options->ExitPolicy, &addr_policy,
+ options->ExitPolicyRejectPrivate))
+ REJECT("Error in ExitPolicy entry.");
+
+ /* The rest of these calls *append* to addr_policy. So don't actually
+ * use the results for anything other than checking if they parse! */
+ if (parse_addr_policy(options->DirPolicy, &addr_policy, -1))
+ REJECT("Error in DirPolicy entry.");
+ if (parse_addr_policy(options->SocksPolicy, &addr_policy, -1))
+ REJECT("Error in SocksPolicy entry.");
+ if (parse_addr_policy(options->ReachableAddresses, &addr_policy,
+ ADDR_POLICY_ACCEPT))
+ REJECT("Error in ReachableAddresses entry.");
+ if (parse_addr_policy(options->ReachableORAddresses, &addr_policy,
+ ADDR_POLICY_ACCEPT))
+ REJECT("Error in ReachableORAddresses entry.");
+ if (parse_addr_policy(options->ReachableDirAddresses, &addr_policy,
+ ADDR_POLICY_ACCEPT))
+ REJECT("Error in ReachableDirAddresses entry.");
+ if (parse_addr_policy(options->AuthDirReject, &addr_policy,
+ ADDR_POLICY_REJECT))
+ REJECT("Error in AuthDirReject entry.");
+ if (parse_addr_policy(options->AuthDirInvalid, &addr_policy,
+ ADDR_POLICY_REJECT))
+ REJECT("Error in AuthDirInvalid entry.");
+
+err:
+ addr_policy_free(addr_policy);
+ return *msg ? -1 : 0;
+#undef REJECT
+}
+
+/* Parse <b>string</b> in the same way that the exit policy
+ * is parsed, and put the processed version in *<b>policy</b>.
+ * Ignore port specifiers.
+ */
+static void
+load_policy_from_option(config_line_t *config, addr_policy_t **policy,
+ int assume_action)
+{
+ addr_policy_t *n;
+ addr_policy_free(*policy);
+ *policy = NULL;
+ parse_addr_policy(config, policy, assume_action);
+ /* ports aren't used. */
+ for (n=*policy; n; n = n->next) {
+ n->prt_min = 1;
+ n->prt_max = 65535;
+ }
+}
+
+void policies_parse_from_options(or_options_t *options)
+{
+ load_policy_from_option(options->SocksPolicy, &socks_policy, -1);
+ load_policy_from_option(options->DirPolicy, &dir_policy, -1);
+ load_policy_from_option(options->AuthDirReject,
+ &authdir_reject_policy, ADDR_POLICY_REJECT);
+ load_policy_from_option(options->AuthDirInvalid,
+ &authdir_invalid_policy, ADDR_POLICY_REJECT);
+ parse_reachable_addresses();
+}
+
+
+/** Compare two provided address policy items, and return -1, 0, or 1
+ * if the first is less than, equal to, or greater than the second. */
+static int
+cmp_single_addr_policy(addr_policy_t *a, addr_policy_t *b)
+{
+ int r;
+ if ((r=((int)a->policy_type - (int)b->policy_type)))
+ return r;
+ if ((r=((int)a->addr - (int)b->addr)))
+ return r;
+ if ((r=((int)a->msk - (int)b->msk)))
+ return r;
+ if ((r=((int)a->prt_min - (int)b->prt_min)))
+ return r;
+ if ((r=((int)a->prt_max - (int)b->prt_max)))
+ return r;
+ return 0;
+}
+
+/** Like cmp_single_addr_policy() above, but looks at the
+ * whole set of policies in each case. */
+int
+cmp_addr_policies(addr_policy_t *a, addr_policy_t *b)
+{
+ int r;
+ while (a && b) {
+ if ((r=cmp_single_addr_policy(a,b)))
+ return r;
+ a = a->next;
+ b = b->next;
+ }
+ if (!a && !b)
+ return 0;
+ if (a)
+ return -1;
+ else
+ return 1;
+}
+
+/** Decide whether a given addr:port is definitely accepted,
+ * definitely rejected, probably accepted, or probably rejected by a
+ * given policy. If <b>addr</b> is 0, we don't know the IP of the
+ * target address. If <b>port</b> is 0, we don't know the port of the
+ * target address.
+ *
+ * For now, the algorithm is pretty simple: we look for definite and
+ * uncertain matches. The first definite match is what we guess; if
+ * it was preceded by no uncertain matches of the opposite policy,
+ * then the guess is definite; otherwise it is probable. (If we
+ * have a known addr and port, all matches are definite; if we have an
+ * unknown addr/port, any address/port ranges other than "all" are
+ * uncertain.)
+ *
+ * We could do better by assuming that some ranges never match typical
+ * addresses (127.0.0.1, and so on). But we'll try this for now.
+ */
+addr_policy_result_t
+compare_addr_to_addr_policy(uint32_t addr, uint16_t port,
+ addr_policy_t *policy)
+{
+ int maybe_reject = 0;
+ int maybe_accept = 0;
+ int match = 0;
+ int maybe = 0;
+ addr_policy_t *tmpe;
+
+ for (tmpe=policy; tmpe; tmpe=tmpe->next) {
+ maybe = 0;
+ if (!addr) {
+ /* Address is unknown. */
+ if ((port >= tmpe->prt_min && port <= tmpe->prt_max) ||
+ (!port && tmpe->prt_min<=1 && tmpe->prt_max>=65535)) {
+ /* The port definitely matches. */
+ if (tmpe->msk == 0) {
+ match = 1;
+ } else {
+ maybe = 1;
+ }
+ } else if (!port) {
+ /* The port maybe matches. */
+ maybe = 1;
+ }
+ } else {
+ /* Address is known */
+ if ((addr & tmpe->msk) == (tmpe->addr & tmpe->msk)) {
+ if (port >= tmpe->prt_min && port <= tmpe->prt_max) {
+ /* Exact match for the policy */
+ match = 1;
+ } else if (!port) {
+ maybe = 1;
+ }
+ }
+ }
+ if (maybe) {
+ if (tmpe->policy_type == ADDR_POLICY_REJECT)
+ maybe_reject = 1;
+ else
+ maybe_accept = 1;
+ }
+ if (match) {
+ if (tmpe->policy_type == ADDR_POLICY_ACCEPT) {
+ /* If we already hit a clause that might trigger a 'reject', than we
+ * can't be sure of this certain 'accept'.*/
+ return maybe_reject ? ADDR_POLICY_PROBABLY_ACCEPTED :
+ ADDR_POLICY_ACCEPTED;
+ } else {
+ return maybe_accept ? ADDR_POLICY_PROBABLY_REJECTED :
+ ADDR_POLICY_REJECTED;
+ }
+ }
+ }
+ /* accept all by default. */
+ return maybe_reject ? ADDR_POLICY_PROBABLY_ACCEPTED : ADDR_POLICY_ACCEPTED;
+}
+
+/** Return true iff the address policy <b>a</b> covers every case that
+ * would be covered by <b>b</b>, so that a,b is redundant. */
+static int
+addr_policy_covers(addr_policy_t *a, addr_policy_t *b)
+{
+ /* We can ignore accept/reject, since "accept *:80, reject *:80" reduces
+ * to "accept *:80". */
+ if (a->msk & ~b->msk) {
+ /* There's a wildcard bit in b->msk that's not a wildcard in a. */
+ return 0;
+ }
+ if ((a->addr & a->msk) != (b->addr & a->msk)) {
+ /* There's a fixed bit in a that's set differently in b. */
+ return 0;
+ }
+ return (a->prt_min <= b->prt_min && a->prt_max >= b->prt_max);
+}
+
+/** Return true iff the address policies <b>a</b> and <b>b</b> intersect,
+ * that is, there exists an address/port that is covered by <b>a</b> that
+ * is also covered by <b>b</b>.
+ */
+static int
+addr_policy_intersects(addr_policy_t *a, addr_policy_t *b)
+{
+ /* All the bits we care about are those that are set in both
+ * netmasks. If they are equal in a and b's networkaddresses
+ * then the networks intersect. If there is a difference,
+ * then they do not. */
+ if (((a->addr ^ b->addr) & a->msk & b->msk) != 0)
+ return 0;
+ if (a->prt_max < b->prt_min || b->prt_max < a->prt_min)
+ return 0;
+ return 1;
+}
+
+/** Add the exit policy described by <b>more</b> to <b>policy</b>.
+ */
+static void
+append_exit_policy_string(addr_policy_t **policy, const char *more)
+{
+ config_line_t tmp;
+
+ tmp.key = NULL;
+ tmp.value = (char*) more;
+ tmp.next = NULL;
+ parse_addr_policy(&tmp, policy, -1);
+}
+
+static int
+expand_exit_policy_aliases(smartlist_t *entries, int assume_action)
+{
+ static const char *prefixes[] = {
+ "0.0.0.0/8", "169.254.0.0/16",
+ "127.0.0.0/8", "192.168.0.0/16", "10.0.0.0/8", "172.16.0.0/12",NULL };
+ int i;
+ char *pre=NULL, *post=NULL;
+ int expanded_any = 0;
+ pre = smartlist_join_strings(entries,",",0,NULL);
+ for (i = 0; i < smartlist_len(entries); ++i) {
+ char *v = smartlist_get(entries, i);
+ const char *cp, *ports;
+ const char *action;
+ int prefix_idx;
+ if (!strcasecmpstart(v, "accept")) {
+ action = "accept ";
+ cp = v+strlen("accept");
+ } else if (!strcasecmpstart(v, "reject")) {
+ action = "reject ";
+ cp = v+strlen("reject");
+ } else if (assume_action >= 0) {
+ action = "";
+ cp = v;
+ } else {
+ log_warn(LD_CONFIG,"Policy '%s' didn't start with accept or reject.", v);
+ tor_free(pre);
+ return -1;
+ }
+ cp = eat_whitespace(cp);
+ if (strcmpstart(cp, "private"))
+ continue; /* No need to expand. */
+ cp += strlen("private");
+ cp = eat_whitespace(cp);
+ if (*cp && *cp != ':')
+ continue; /* It wasn't "private" after all. */
+ ports = cp;
+ /* Okay. We're going to replace entries[i] with a bunch of new entries,
+ * in order. */
+ smartlist_del_keeporder(entries, i);
+ for (prefix_idx = 0; prefixes[prefix_idx]; ++prefix_idx) {
+ size_t replacement_len = 16+strlen(prefixes[prefix_idx])+strlen(ports);
+ char *replacement = tor_malloc(replacement_len);
+ tor_snprintf(replacement, replacement_len, "%s%s%s",
+ action, prefixes[prefix_idx], ports);
+ smartlist_insert(entries, i++, replacement);
+ }
+ tor_free(v);
+ expanded_any = 1;
+ --i;
+ }
+ post = smartlist_join_strings(entries,",",0,NULL);
+ if (expanded_any)
+ log_info(LD_CONFIG, "Expanded '%s' to '%s'", pre, post);
+ tor_free(pre);
+ tor_free(post);
+ return expanded_any;
+}
+
+/** Detect and excise "dead code" from the policy *<b>dest</b>. */
+static void
+exit_policy_remove_redundancies(addr_policy_t **dest)
+{
+ addr_policy_t *ap, *tmp, *victim, *previous;
+
+ /* Step one: find a *:* entry and cut off everything after it. */
+ for (ap=*dest; ap; ap=ap->next) {
+ if (ap->msk == 0 && ap->prt_min <= 1 && ap->prt_max >= 65535) {
+ /* This is a catch-all line -- later lines are unreachable. */
+ if (ap->next) {
+ addr_policy_free(ap->next);
+ ap->next = NULL;
+ }
+ }
+ }
+
+ /* Step two: for every entry, see if there's a redundant entry
+ * later on, and remove it. */
+ for (ap=*dest; ap; ap=ap->next) {
+ tmp=ap;
+ while (tmp) {
+ if (tmp->next && addr_policy_covers(ap, tmp->next)) {
+ log(LOG_INFO, LD_CONFIG, "Removing exit policy %s. It is made "
+ "redundant by %s.", tmp->next->string, ap->string);
+ victim = tmp->next;
+ tmp->next = victim->next;
+ victim->next = NULL;
+ addr_policy_free(victim);
+ } else {
+ tmp=tmp->next;
+ }
+ }
+ }
+
+ /* Step three: for every entry A, see if there's an entry B making this one
+ * redundant later on. This is the case if A and B are of the same type
+ * (accept/reject), A is a subset of B, and there is no other entry of
+ * different type in between those two that intersects with A.
+ *
+ * Anybody want to doublecheck the logic here? XXX
+ */
+ ap = *dest;
+ previous = NULL;
+ while (ap) {
+ for (tmp=ap->next; tmp; tmp=tmp->next) {
+ if (ap->policy_type != tmp->policy_type &&
+ addr_policy_intersects(ap, tmp)) {
+ tmp = NULL; /* so that we advance previous and ap */
+ break;
+ }
+ if (ap->policy_type == tmp->policy_type &&
+ addr_policy_covers(tmp, ap)) {
+ log(LOG_INFO, LD_CONFIG, "Removing exit policy %s. It is made "
+ "redundant by %s.", ap->string, tmp->string);
+ victim = ap;
+ ap = ap->next;
+
+ if (previous) {
+ assert(previous->next == victim);
+ previous->next = victim->next;
+ } else {
+ assert(*dest == victim);
+ *dest = victim->next;
+ }
+
+ victim->next = NULL;
+ addr_policy_free(victim);
+ break;
+ }
+ }
+ if (!tmp) {
+ previous = ap;
+ ap = ap->next;
+ }
+ }
+}
+
+#define DEFAULT_EXIT_POLICY \
+ "reject *:25,reject *:119,reject *:135-139,reject *:445," \
+ "reject *:465,reject *:587,reject *:1214,reject *:4661-4666," \
+ "reject *:6346-6429,reject *:6699,reject *:6881-6999,accept *:*"
+
+/** Parse the exit policy <b>cfg</b> into the linked list *<b>dest</b>. If
+ * cfg doesn't end in an absolute accept or reject, add the default exit
+ * policy afterwards. If <b>rejectprivate</b> is true, prepend
+ * "reject private:*" to the policy. Return -1 if we can't parse cfg,
+ * else return 0.
+ *
+ */
+int
+policies_parse_exit_policy(config_line_t *cfg, addr_policy_t **dest,
+ int rejectprivate)
+{
+ if (rejectprivate)
+ append_exit_policy_string(dest, "reject private:*");
+ if (parse_addr_policy(cfg, dest, -1))
+ return -1;
+ append_exit_policy_string(dest, DEFAULT_EXIT_POLICY);
+
+ exit_policy_remove_redundancies(dest);
+ return 0;
+}
+
+/** Return true iff <b>ri</b> is "useful as an exit node", meaning
+ * it allows exit to at least one /8 address space for at least
+ * one of ports 80, 443, and 6667. */
+int
+exit_policy_is_general_exit(addr_policy_t *policy)
+{
+ static const int ports[] = { 80, 443, 6667 };
+ int n_allowed = 0;
+ int i;
+ for (i = 0; i < 3; ++i) {
+ struct addr_policy_t *p = policy;
+ for ( ; p; p = p->next) {
+ if (p->prt_min > ports[i] || p->prt_max < ports[i])
+ continue; /* Doesn't cover our port. */
+ if ((p->msk & 0x00fffffful) != 0)
+ continue; /* Narrower than a /8. */
+ if ((p->addr & 0xff000000ul) == 0x7f000000ul)
+ continue; /* 127.x */
+ /* We have a match that is at least a /8. */
+ if (p->policy_type == ADDR_POLICY_ACCEPT)
+ ++n_allowed;
+ break;
+ }
+ }
+ return n_allowed > 0;
+}
+
+/** Release all storage held by <b>p</b> */
+void
+addr_policy_free(addr_policy_t *p)
+{
+ addr_policy_t *e;
+
+ while (p) {
+ e = p;
+ p = p->next;
+ tor_free(e->string);
+ tor_free(e);
+ }
+}
+
+void
+policies_free_all(void)
+{
+ addr_policy_free(reachable_or_addr_policy);
+ reachable_or_addr_policy = NULL;
+ addr_policy_free(reachable_dir_addr_policy);
+ reachable_dir_addr_policy = NULL;
+ addr_policy_free(socks_policy);
+ socks_policy = NULL;
+ addr_policy_free(dir_policy);
+ dir_policy = NULL;
+ addr_policy_free(authdir_reject_policy);
+ authdir_reject_policy = NULL;
+ addr_policy_free(authdir_invalid_policy);
+ authdir_invalid_policy = NULL;
+}
+
generated by cgit v1.2.3 (git 2.45.0) at 2025-01-08 19:26:53 +0000