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/* Copyright (c) 2015-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#include "core/or/or.h"
#include "lib/process/setuid.h"
#ifdef HAVE_SYS_CAPABILITY_H
#include <sys/capability.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#define TEST_BUILT_WITH_CAPS 0
#define TEST_HAVE_CAPS 1
#define TEST_ROOT_CAN_BIND_LOW 2
#define TEST_SETUID 3
#define TEST_SETUID_KEEPCAPS 4
#define TEST_SETUID_STRICT 5
static const struct {
const char *name;
int test_id;
} which_test[] = {
{ "built-with-caps", TEST_BUILT_WITH_CAPS },
{ "have-caps", TEST_HAVE_CAPS },
{ "root-bind-low", TEST_ROOT_CAN_BIND_LOW },
{ "setuid", TEST_SETUID },
{ "setuid-keepcaps", TEST_SETUID_KEEPCAPS },
{ "setuid-strict", TEST_SETUID_STRICT },
{ NULL, 0 }
};
#if !defined(_WIN32)
/* Returns the first port that we think we can bind to without special
* permissions. Usually this function returns 1024. */
static uint16_t
unprivileged_port_range_start(void)
{
uint16_t result = 1024;
#if defined(__linux__)
char *content = NULL;
content = read_file_to_str(
"/proc/sys/net/ipv4/ip_unprivileged_port_start",
0,
NULL);
if (content != NULL) {
int ok = 1;
uint16_t tmp_result;
tmp_result = (uint16_t)tor_parse_long(content, 10, 0, 65535, &ok, NULL);
if (ok) {
result = tmp_result;
} else {
fprintf(stderr,
"Unable to convert ip_unprivileged_port_start to integer: %s\n",
content);
}
}
tor_free(content);
#endif /* defined(__linux__) */
return result;
}
#define PORT_TEST_RANGE_START 600
#define PORT_TEST_RANGE_END 1024
/* 0 on no, 1 on yes, -1 on failure. */
static int
check_can_bind_low_ports(void)
{
int port;
struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
for (port = PORT_TEST_RANGE_START; port < PORT_TEST_RANGE_END; ++port) {
sin.sin_port = htons(port);
tor_socket_t fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (! SOCKET_OK(fd)) {
perror("socket");
return -1;
}
int one = 1;
if (setsockopt(fd, SOL_SOCKET,SO_REUSEADDR, (void*)&one,
(socklen_t)sizeof(one))) {
perror("setsockopt");
tor_close_socket_simple(fd);
return -1;
}
int res = bind(fd, (struct sockaddr *)&sin, sizeof(sin));
tor_close_socket_simple(fd);
if (res == 0) {
/* bind was successful */
return 1;
} else if (errno == EACCES || errno == EPERM) {
/* Got a permission-denied error. */
return 0;
} else if (errno == EADDRINUSE) {
/* Huh; somebody is using that port. */
} else {
perror("bind");
}
}
return -1;
}
#endif /* !defined(_WIN32) */
int
main(int argc, char **argv)
{
#if defined(_WIN32)
(void) argc;
(void) argv;
(void) which_test;
fprintf(stderr, "This test is not supported on your OS.\n");
return 77;
#else /* !defined(_WIN32) */
const char *username;
const char *testname;
if (argc != 3) {
fprintf(stderr, "I want 2 arguments: a username and a command.\n");
return 1;
}
if (getuid() != 0) {
fprintf(stderr, "This test only works when it's run as root.\n");
return 1;
}
username = argv[1];
testname = argv[2];
int test_id = -1;
int i;
for (i = 0; which_test[i].name; ++i) {
if (!strcmp(which_test[i].name, testname)) {
test_id = which_test[i].test_id;
break;
}
}
if (test_id == -1) {
fprintf(stderr, "Unrecognized test '%s'\n", testname);
return 1;
}
#ifdef HAVE_LINUX_CAPABILITIES
const int have_cap_support = 1;
#else
const int have_cap_support = 0;
#endif
int okay;
init_logging(1);
log_severity_list_t sev;
memset(&sev, 0, sizeof(sev));
set_log_severity_config(LOG_WARN, LOG_ERR, &sev);
add_stream_log(&sev, "", fileno(stderr));
switch (test_id)
{
case TEST_BUILT_WITH_CAPS:
/* Succeed if we were built with capability support. */
okay = have_cap_support;
break;
case TEST_HAVE_CAPS:
/* Succeed if "capabilities work" == "we were built with capability
* support." */
okay = have_cap_support == have_capability_support();
break;
case TEST_ROOT_CAN_BIND_LOW:
/* Succeed if root can bind low ports. */
okay = check_can_bind_low_ports() == 1;
break;
case TEST_SETUID:
/* Succeed if we can do a setuid with no capability retention, and doing
* so makes us lose the ability to bind low ports */
case TEST_SETUID_KEEPCAPS:
/* Succeed if we can do a setuid with capability retention, and doing so
* does not make us lose the ability to bind low ports */
{
const int keepcaps = (test_id == TEST_SETUID_KEEPCAPS);
okay = switch_id(username, keepcaps ? SWITCH_ID_KEEP_BINDLOW : 0) == 0;
if (okay) {
/* Only run this check if there are ports we may not be able to bind
* to. */
const uint16_t min_port = unprivileged_port_range_start();
if (min_port >= PORT_TEST_RANGE_START &&
min_port < PORT_TEST_RANGE_END) {
okay = check_can_bind_low_ports() == keepcaps;
} else {
fprintf(stderr,
"Skipping check for whether we can bind to any "
"privileged ports as the user system seems to "
"allow us to bind to ports even without any "
"capabilities set.\n");
}
}
break;
}
case TEST_SETUID_STRICT:
/* Succeed if, after a setuid, we cannot setuid back, and we cannot
* re-grab any capabilities. */
okay = switch_id(username, SWITCH_ID_KEEP_BINDLOW) == 0;
if (okay) {
/* We'd better not be able to setuid back! */
if (setuid(0) == 0 || errno != EPERM) {
okay = 0;
}
}
#ifdef HAVE_LINUX_CAPABILITIES
if (okay) {
cap_t caps = cap_get_proc();
const cap_value_t caplist[] = {
CAP_SETUID,
};
cap_set_flag(caps, CAP_PERMITTED, 1, caplist, CAP_SET);
if (cap_set_proc(caps) == 0 || errno != EPERM) {
okay = 0;
}
cap_free(caps);
}
#endif /* defined(HAVE_LINUX_CAPABILITIES) */
break;
default:
fprintf(stderr, "Unsupported test '%s'\n", testname);
okay = 0;
break;
}
if (!okay) {
fprintf(stderr, "Test %s failed!\n", testname);
}
return (okay ? 0 : 1);
#endif /* defined(_WIN32) */
}
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