commit 63b404911441a7691949c475a374569d668a1b32 Author: Neel Chauhan neel@neelc.org Date: Sat Mar 2 21:25:35 2019 -0500

Make tor_addr_is_internal_() RFC6598 (Carrier Grade NAT) aware

Fixes 28525. --- changes/bug28525 | 8 ++++++++ src/common/address.c | 19 +++++++++++++++---- src/test/test_addr.c | 18 ++++++++++++++++++ 3 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/changes/bug28525 b/changes/bug28525 new file mode 100644 index 000000000..392a9265e --- /dev/null +++ b/changes/bug28525 @@ -0,0 +1,8 @@ + o Minor bugfixes (address selection): + - Make Tor aware of the RFC 6598 (Carrier Grade NAT) IP range, which is the + subnet 100.64.0.0/10. This is deployed by many ISPs as an alternative to + RFC 1918 that does not break existing internal networks. This patch fixes + security issues caused by RFC 6518 by blocking control ports on these + addresses and warns users if client ports or ExtORPorts are listening on + a RFC 6598 address. Fixes bug 28525; bugfix on 0.4.1.1-alpha. Patch by + Neel Chauhan. diff --git a/src/common/address.c b/src/common/address.c index 794345a13..71d380538 100644 --- a/src/common/address.c +++ b/src/common/address.c @@ -348,9 +348,18 @@ tor_addr_lookup(const char *name, uint16_t family, tor_addr_t *addr) } }

-/** Return true iff <b>ip</b> is an IP reserved to localhost or local networks - * in RFC1918 or RFC4193 or RFC4291. (fec0::/10, deprecated by RFC3879, is - * also treated as internal for now.) +/** Return true iff <b>ip</b> is an IP reserved to localhost or local networks. + * + * If <b>ip</b> is in RFC1918 or RFC4193 or RFC4291, we will return true. + * (fec0::/10, deprecated by RFC3879, is also treated as internal for now + * and will return true.) + * + * If <b>ip</b> is 0.0.0.0 or 100.64.0.0/10 (RFC6598), we will act as: + * - Internal if <b>for_listening</b> is 0, as these addresses are not + * routable on the internet and we won't be publicly accessible to clients. + * - External if <b>for_listening</b> is 1, as clients could connect to us + * from the internet (in the case of 0.0.0.0) or a service provider's + * internal network (in the case of RFC6598). */ int tor_addr_is_internal_(const tor_addr_t *addr, int for_listening, @@ -398,11 +407,13 @@ tor_addr_is_internal_(const tor_addr_t *addr, int for_listening,

return 0; } else if (v_family == AF_INET) { - if (for_listening && !iph4) /* special case for binding to 0.0.0.0 */ + /* special case for binding to 0.0.0.0 or 100.64/10 (RFC6598) */ + if (for_listening && (!iph4 || ((iph4 & 0xffc00000) == 0x64400000))) return 0; if (((iph4 & 0xff000000) == 0x0a000000) || /* 10/8 */ ((iph4 & 0xff000000) == 0x00000000) || /* 0/8 */ ((iph4 & 0xff000000) == 0x7f000000) || /* 127/8 */ + ((iph4 & 0xffc00000) == 0x64400000) || /* 100.64/10 */ ((iph4 & 0xffff0000) == 0xa9fe0000) || /* 169.254/16 */ ((iph4 & 0xfff00000) == 0xac100000) || /* 172.16/12 */ ((iph4 & 0xffff0000) == 0xc0a80000)) /* 192.168/16 */ diff --git a/src/test/test_addr.c b/src/test/test_addr.c index be440a092..5c4b6449c 100644 --- a/src/test/test_addr.c +++ b/src/test/test_addr.c @@ -1063,6 +1063,23 @@ test_addr_make_null(void *data) tor_free(zeros); }

+#define TEST_ADDR_INTERNAL(a, for_listening, rv) STMT_BEGIN \ + tor_addr_t t; \ + tt_int_op(tor_inet_pton(AF_INET, a, &t.addr.in_addr), OP_EQ, 1); \ + t.family = AF_INET; \ + tt_int_op(tor_addr_is_internal(&t, for_listening), OP_EQ, rv); \ + STMT_END; + +static void +test_addr_rfc6598(void *arg) +{ + (void)arg; + TEST_ADDR_INTERNAL("100.64.0.1", 0, 1); + TEST_ADDR_INTERNAL("100.64.0.1", 1, 0); + done: + ; +} + #define ADDR_LEGACY(name) \ { #name, test_addr_ ## name , 0, NULL, NULL }

@@ -1076,6 +1093,7 @@ struct testcase_t addr_tests[] = { { "sockaddr_to_str", test_addr_sockaddr_to_str, 0, NULL, NULL }, { "is_loopback", test_addr_is_loopback, 0, NULL, NULL }, { "make_null", test_addr_make_null, 0, NULL, NULL }, + { "rfc6598", test_addr_rfc6598, 0, NULL, NULL }, END_OF_TESTCASES };