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Fix IPv6 support in policy_summary_reject and policy_summary_accept

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This interim fix results in too many IPv6 rejections.

No behaviour change for IPv4 counts, except for overflow fixes that
would require 4 billion redundant 0.0.0.0/0 policy entries to trigger.

Part of 21357
This commit is contained in:
teor 2017-02-01 15:28:46 +11:00 committed by Nick Mathewson
parent 82850d0da6
commit 4667a40ca9
1 changed files with 47 additions and 13 deletions
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60
src/or/policies.c
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@ -2304,6 +2304,12 @@ policy_summary_item_split(policy_summary_item_t* old, uint16_t new_starts)
* IPv4 /8 address blocks */
#define REJECT_CUTOFF_COUNT_IPV4 (U64_LITERAL(1) << \
(IPV4_BITS - 7))
#define IPV6_BITS (128)
/* Ports are rejected in an IPv6 summary if they are rejected in at least one
* IPv6 /64. */
#define REJECT_CUTOFF_COUNT_IPV6 (UINT64_MAX)
/** Split an exit policy summary so that prt_min and prt_max
* fall at exactly the start and end of an item respectively.
*/
@ -2336,40 +2342,68 @@ policy_summary_split(smartlist_t *summary,
return start_at_index;
}
/** Mark port ranges as accepted if they are below the reject_count */
/** Mark port ranges as accepted if they are below the reject_count for family
*/
static void
policy_summary_accept(smartlist_t *summary,
uint16_t prt_min, uint16_t prt_max)
uint16_t prt_min, uint16_t prt_max,
sa_family_t family)
{
tor_assert_nonfatal_once(family == AF_INET || family == AF_INET6);
uint64_t family_reject_count = ((family == AF_INET) ?
REJECT_CUTOFF_COUNT_IPV4 :
REJECT_CUTOFF_COUNT_IPV6);
int i = policy_summary_split(summary, prt_min, prt_max);
while (i < smartlist_len(summary) &&
AT(i)->prt_max <= prt_max) {
if (!AT(i)->accepted &&
AT(i)->reject_count <= REJECT_CUTOFF_COUNT_IPV4)
AT(i)->reject_count <= family_reject_count)
AT(i)->accepted = 1;
i++;
}
tor_assert(i < smartlist_len(summary) || prt_max==65535);
}
/** Count the number of addresses in a network with prefixlen maskbits
* against the given portrange. */
/** Count the number of addresses in a network in family with prefixlen
* maskbits against the given portrange. */
static void
policy_summary_reject(smartlist_t *summary,
maskbits_t maskbits,
uint16_t prt_min, uint16_t prt_max)
uint16_t prt_min, uint16_t prt_max,
sa_family_t family)
{
tor_assert_nonfatal_once(family == AF_INET || family == AF_INET6);
int i = policy_summary_split(summary, prt_min, prt_max);
/* XXX: ipv4 specific */
/* The length of a single address mask */
int addrbits = IPV4_BITS;
int addrbits = (family == AF_INET) ? IPV4_BITS : IPV6_BITS;
tor_assert_nonfatal_once(addrbits >= maskbits);
uint64_t count = (U64_LITERAL(1) << (addrbits-maskbits));
uint64_t count = 0;
if (addrbits - maskbits >= 64) {
tor_assert_nonfatal_once(family == AF_INET6);
/* The address range is so large, it's an automatic rejection for all ports
* in the range. */
count = UINT64_MAX;
} else {
count = (U64_LITERAL(1) << (addrbits - maskbits));
}
tor_assert_nonfatal_once(count > 0);
while (i < smartlist_len(summary) &&
AT(i)->prt_max <= prt_max) {
AT(i)->reject_count += count;
if (AT(i)->reject_count <= UINT64_MAX - count) {
AT(i)->reject_count += count;
} else {
/* IPv4 would require a 4-billion address redundant policy to get here,
* but IPv6 just needs to have ::/0 */
if (family == AF_INET) {
tor_assert_nonfatal_unreached_once();
}
/* If we do get here, use saturating arithmetic */
AT(i)->reject_count = UINT64_MAX;
}
i++;
}
tor_assert(i < smartlist_len(summary) || prt_max==65535);
@ -2389,7 +2423,7 @@ policy_summary_add_item(smartlist_t *summary, addr_policy_t *p)
{
if (p->policy_type == ADDR_POLICY_ACCEPT) {
if (p->maskbits == 0) {
policy_summary_accept(summary, p->prt_min, p->prt_max);
policy_summary_accept(summary, p->prt_min, p->prt_max, p->addr.family);
}
} else if (p->policy_type == ADDR_POLICY_REJECT) {
@ -2410,7 +2444,8 @@ policy_summary_add_item(smartlist_t *summary, addr_policy_t *p)
}
if (!is_private) {
policy_summary_reject(summary, p->maskbits, p->prt_min, p->prt_max);
policy_summary_reject(summary, p->maskbits, p->prt_min, p->prt_max,
p->addr.family);
}
} else
tor_assert(0);
@ -2444,7 +2479,6 @@ policy_summarize(smartlist_t *policy, sa_family_t family)
}
if (f != family)
continue;
/* XXXX-ipv6 More family work is needed */
policy_summary_add_item(summary, p);
} SMARTLIST_FOREACH_END(p);