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wg-quick: android: refactor and add incoming allow rules

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Suggested-by: Yağmur Oymak <yagmur.oymak@gmail.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2019-07-08 12:56:41 +02:00
parent b30e74b595
commit 6a5906608c
1 changed files with 73 additions and 65 deletions
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138
src/wg-quick/android.c
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@ -263,30 +263,84 @@ static void add_if(const char *iface)
static void del_if(const char *iface) static void del_if(const char *iface)
{ {
DEFINE_CMD(c); DEFINE_CMD(c_rule);
_cleanup_regfree_ regex_t reg = { 0 }; DEFINE_CMD(c_iptables);
DEFINE_CMD(c_ip6tables);
_cleanup_regfree_ regex_t rule_reg = { 0 }, iptables_reg = { 0 };
regmatch_t matches[2]; regmatch_t matches[2];
char *netid = NULL; char *netid = NULL;
_cleanup_free_ char *regex = concat("0xc([0-9a-f]+)/0xcffff lookup ", iface, NULL); _cleanup_free_ char *rule_regex = concat("0xc([0-9a-f]+)/0xcffff lookup ", iface, NULL);
_cleanup_free_ char *iptables_regex = concat("^-A (.* --comment \"wireguard rule ", iface, "\"[^\n]*)\n*$", NULL);
xregcomp(&reg, regex, REG_EXTENDED); xregcomp(&rule_reg, rule_regex, REG_EXTENDED);
xregcomp(&iptables_reg, iptables_regex, REG_EXTENDED);
cmd("iptables -D OUTPUT -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface);
cmd("ip6tables -D OUTPUT -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface);
cmd("ip link del %s", iface); cmd("ip link del %s", iface);
for (char *ret = cmd_ret(&c, "ip rule show"); ret; ret = cmd_ret(&c, NULL)) {
if (!regexec(&reg, ret, ARRAY_SIZE(matches), matches, 0)) { for (char *rule = cmd_ret(&c_iptables, "iptables-save"); rule; rule = cmd_ret(&c_iptables, NULL)) {
ret[matches[1].rm_eo] = '\0'; if (!regexec(&iptables_reg, rule, ARRAY_SIZE(matches), matches, 0)) {
netid = &ret[matches[1].rm_so]; rule[matches[1].rm_eo] = '\0';
cmd("iptables -D %s", &rule[matches[1].rm_so]);
}
}
for (char *rule = cmd_ret(&c_ip6tables, "ip6tables-save"); rule; rule = cmd_ret(&c_ip6tables, NULL)) {
if (!regexec(&iptables_reg, rule, ARRAY_SIZE(matches), matches, 0)) {
rule[matches[1].rm_eo] = '\0';
cmd("ip6tables -D %s", &rule[matches[1].rm_so]);
}
}
for (char *rule = cmd_ret(&c_rule, "ip rule show"); rule; rule = cmd_ret(&c_rule, NULL)) {
if (!regexec(&rule_reg, rule, ARRAY_SIZE(matches), matches, 0)) {
rule[matches[1].rm_eo] = '\0';
netid = &rule[matches[1].rm_so];
break; break;
} }
} }
if (netid) if (netid)
cndc("network destroy %lu", strtoul(netid, NULL, 16)); cndc("network destroy %lu", strtoul(netid, NULL, 16));
} }
static void up_if(unsigned int *netid, const char *iface) static bool should_block_ipv6(const char *iface)
{
DEFINE_CMD(c);
bool has_ipv6 = false, has_all_none = true;
for (char *endpoint = cmd_ret(&c, "wg show %s endpoints", iface); endpoint; endpoint = cmd_ret(&c, NULL)) {
char *start = strchr(endpoint, '\t');
if (!start)
continue;
++start;
if (start[0] != '(')
has_all_none = false;
if (start[0] == '[')
has_ipv6 = true;
}
return !has_ipv6 && !has_all_none;
}
static uint16_t determine_listen_port(const char *iface)
{
DEFINE_CMD(c);
unsigned long listen_port = 0;
char *value;
cmd("ip link set up dev %s", iface);
value = cmd_ret(&c, "wg show %s listen-port", iface);
if (!value)
goto set_back_down;
listen_port = strtoul(value, NULL, 10);
if (listen_port > UINT16_MAX || !listen_port) {
listen_port = 0;
goto set_back_down;
}
set_back_down:
cmd("ip link set down dev %s", iface);
return listen_port;
}
static void up_if(unsigned int *netid, const char *iface, uint16_t listen_port)
{ {
srandom(time(NULL) ^ getpid()); /* Not real randomness. */ srandom(time(NULL) ^ getpid()); /* Not real randomness. */
@ -296,6 +350,10 @@ static void up_if(unsigned int *netid, const char *iface)
cmd("wg set %s fwmark 0x20000", iface); cmd("wg set %s fwmark 0x20000", iface);
cmd("iptables -I OUTPUT 1 -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface); cmd("iptables -I OUTPUT 1 -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface);
cmd("ip6tables -I OUTPUT 1 -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface); cmd("ip6tables -I OUTPUT 1 -m mark --mark 0x20000 -j ACCEPT -m comment --comment \"wireguard rule %s\"", iface);
if (listen_port) {
cmd("iptables -I INPUT 1 -p udp --dport %u -j ACCEPT -m comment --comment \"wireguard rule %s\"", listen_port, iface);
cmd("ip6tables -I INPUT 1 -p udp --dport %u -j %s -m comment --comment \"wireguard rule %s\"", listen_port, should_block_ipv6(iface) ? "DROP" : "ACCEPT", iface);
}
cndc("interface setcfg %s up", iface); cndc("interface setcfg %s up", iface);
cndc("network create %u vpn 1 1", *netid); cndc("network create %u vpn 1 1", *netid);
cndc("network interface add %u %s", *netid, iface); cndc("network interface add %u %s", *netid, iface);
@ -520,56 +578,6 @@ static void set_routes(const char *iface, unsigned int netid)
} }
} }
static void maybe_block_ipv6(const char *iface)
{
DEFINE_CMD(c_endpoints);
DEFINE_CMD(c_listenport);
bool has_ipv6 = false, has_all_none = true;
char *value;
unsigned long listenport;
for (char *endpoint = cmd_ret(&c_endpoints, "wg show %s endpoints", iface); endpoint; endpoint = cmd_ret(&c_endpoints, NULL)) {
char *start = strchr(endpoint, '\t');
if (!start)
continue;
++start;
if (start[0] != '(')
has_all_none = false;
if (start[0] == '[')
has_ipv6 = true;
}
if (has_ipv6 || has_all_none)
return;
cmd("ip link set up dev %s", iface);
value = cmd_ret(&c_listenport, "wg show %s listen-port", iface);
if (!value)
goto set_back_down;
listenport = strtoul(value, NULL, 10);
if (listenport > UINT16_MAX || !listenport)
goto set_back_down;
cmd("ip6tables -I INPUT 1 -p udp --dport %lu -j DROP -m comment --comment \"wireguard rule %s\"", listenport, iface);
set_back_down:
cmd("ip link set down dev %s", iface);
}
static void maybe_unblock_ipv6(const char *iface)
{
regmatch_t matches[2];
_cleanup_regfree_ regex_t reg = { 0 };
_cleanup_free_ char *regex = concat("^-A (.* --comment \"wireguard rule ", iface, "\"[^\n]*)\n*$", NULL);
DEFINE_CMD(c);
xregcomp(&reg, regex, REG_EXTENDED);
for (char *rule = cmd_ret(&c, "ip6tables-save"); rule; rule = cmd_ret(&c, NULL)) {
if (!regexec(&reg, rule, ARRAY_SIZE(matches), matches, 0)) {
rule[matches[1].rm_eo] = '\0';
cmd("ip6tables -D %s", &rule[matches[1].rm_so]);
}
}
}
static void set_config(const char *iface, const char *config) static void set_config(const char *iface, const char *config)
{ {
FILE *config_writer; FILE *config_writer;
@ -641,6 +649,7 @@ static void cmd_up(const char *iface, const char *config, unsigned int mtu, cons
{ {
DEFINE_CMD(c); DEFINE_CMD(c);
unsigned int netid = 0; unsigned int netid = 0;
uint16_t listen_port;
if (cmd_ret(&c, "ip link show dev %s 2>/dev/null", iface)) { if (cmd_ret(&c, "ip link show dev %s 2>/dev/null", iface)) {
fprintf(stderr, "Error: %s already exists\n", iface); fprintf(stderr, "Error: %s already exists\n", iface);
@ -652,9 +661,9 @@ static void cmd_up(const char *iface, const char *config, unsigned int mtu, cons
add_if(iface); add_if(iface);
set_config(iface, config); set_config(iface, config);
maybe_block_ipv6(iface); listen_port = determine_listen_port(iface);
set_addr(iface, addrs); set_addr(iface, addrs);
up_if(&netid, iface); up_if(&netid, iface, listen_port);
set_dnses(netid, dnses); set_dnses(netid, dnses);
set_routes(iface, netid); set_routes(iface, netid);
set_mtu(iface, mtu); set_mtu(iface, mtu);
@ -686,7 +695,6 @@ static void cmd_down(const char *iface)
} }
del_if(iface); del_if(iface);
maybe_unblock_ipv6(iface);
broadcast_change(); broadcast_change();
exit(EXIT_SUCCESS); exit(EXIT_SUCCESS);
} }