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misc.c
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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif
#include "syshead.h"
#include "buffer.h"
#include "misc.h"
#include "base64.h"
#include "tun.h"
#include "error.h"
#include "otime.h"
#include "plugin.h"
#include "options.h"
#include "manage.h"
#include "crypto.h"
#include "route.h"
#include "console.h"
#include "win32.h"
#include "memdbg.h"
#ifdef ENABLE_IPROUTE
const char *iproute_path = IPROUTE_PATH; /* GLOBAL */
#endif
/* contains an SSEC_x value defined in misc.h */
int script_security = SSEC_BUILT_IN; /* GLOBAL */
/*
* Pass tunnel endpoint and MTU parms to a user-supplied script.
* Used to execute the up/down script/plugins.
*/
void
run_up_down (const char *command,
const struct plugin_list *plugins,
int plugin_type,
const char *arg,
const char *dev_type,
int tun_mtu,
int link_mtu,
const char *ifconfig_local,
const char* ifconfig_remote,
const char *context,
const char *signal_text,
const char *script_type,
struct env_set *es)
{
struct gc_arena gc = gc_new ();
if (signal_text)
setenv_str (es, "signal", signal_text);
setenv_str (es, "script_context", context);
setenv_int (es, "tun_mtu", tun_mtu);
setenv_int (es, "link_mtu", link_mtu);
setenv_str (es, "dev", arg);
if (dev_type)
setenv_str (es, "dev_type", dev_type);
if (!ifconfig_local)
ifconfig_local = "";
if (!ifconfig_remote)
ifconfig_remote = "";
if (!context)
context = "";
if (plugin_defined (plugins, plugin_type))
{
struct argv argv = argv_new ();
ASSERT (arg);
argv_printf (&argv,
"%s %d %d %s %s %s",
arg,
tun_mtu, link_mtu,
ifconfig_local, ifconfig_remote,
context);
if (plugin_call (plugins, plugin_type, &argv, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
msg (M_FATAL, "ERROR: up/down plugin call failed");
argv_reset (&argv);
}
if (command)
{
struct argv argv = argv_new ();
ASSERT (arg);
setenv_str (es, "script_type", script_type);
argv_printf (&argv,
"%sc %s %d %d %s %s %s",
command,
arg,
tun_mtu, link_mtu,
ifconfig_local, ifconfig_remote,
context);
argv_msg (M_INFO, &argv);
openvpn_run_script (&argv, es, S_FATAL, "--up/--down");
argv_reset (&argv);
}
gc_free (&gc);
}
/* Write our PID to a file */
void
write_pid (const char *filename)
{
if (filename)
{
unsigned int pid = 0;
FILE *fp = platform_fopen (filename, "w");
if (!fp)
msg (M_ERR, "Open error on pid file %s", filename);
pid = platform_getpid ();
fprintf(fp, "%u\n", pid);
if (fclose (fp))
msg (M_ERR, "Close error on pid file %s", filename);
}
}
/*
* Set standard file descriptors to /dev/null
*/
void
set_std_files_to_null (bool stdin_only)
{
#if defined(HAVE_DUP) && defined(HAVE_DUP2)
int fd;
if ((fd = open ("/dev/null", O_RDWR, 0)) != -1)
{
dup2 (fd, 0);
if (!stdin_only)
{
dup2 (fd, 1);
dup2 (fd, 2);
}
if (fd > 2)
close (fd);
}
#endif
}
/*
* dup inetd/xinetd socket descriptor and save
*/
int inetd_socket_descriptor = SOCKET_UNDEFINED; /* GLOBAL */
void
save_inetd_socket_descriptor (void)
{
inetd_socket_descriptor = INETD_SOCKET_DESCRIPTOR;
#if defined(HAVE_DUP) && defined(HAVE_DUP2)
/* use handle passed by inetd/xinetd */
if ((inetd_socket_descriptor = dup (INETD_SOCKET_DESCRIPTOR)) < 0)
msg (M_ERR, "INETD_SOCKET_DESCRIPTOR dup(%d) failed", INETD_SOCKET_DESCRIPTOR);
set_std_files_to_null (true);
#endif
}
/*
* Warn if a given file is group/others accessible.
*/
void
warn_if_group_others_accessible (const char* filename)
{
#ifndef WIN32
#ifdef HAVE_STAT
if (strcmp (filename, INLINE_FILE_TAG))
{
struct stat st;
if (stat (filename, &st))
{
msg (M_WARN | M_ERRNO, "WARNING: cannot stat file '%s'", filename);
}
else
{
if (st.st_mode & (S_IRWXG|S_IRWXO))
msg (M_WARN, "WARNING: file '%s' is group or others accessible", filename);
}
}
#endif
#endif
}
/*
* Print an error message based on the status code returned by system().
*/
const char *
system_error_message (int stat, struct gc_arena *gc)
{
struct buffer out = alloc_buf_gc (256, gc);
#ifdef WIN32
if (stat == -1)
buf_printf (&out, "external program did not execute -- ");
buf_printf (&out, "returned error code %d", stat);
#else
if (stat == -1)
buf_printf (&out, "external program fork failed");
else if (!WIFEXITED (stat))
buf_printf (&out, "external program did not exit normally");
else
{
const int cmd_ret = WEXITSTATUS (stat);
if (!cmd_ret)
buf_printf (&out, "external program exited normally");
else if (cmd_ret == 127)
buf_printf (&out, "could not execute external program");
else
buf_printf (&out, "external program exited with error status: %d", cmd_ret);
}
#endif
return (const char *)out.data;
}
/*
* Wrapper around openvpn_execve
*/
bool
openvpn_execve_check (const struct argv *a, const struct env_set *es, const unsigned int flags, const char *error_message)
{
struct gc_arena gc = gc_new ();
const int stat = openvpn_execve (a, es, flags);
int ret = false;
if (platform_system_ok (stat))
ret = true;
else
{
if (error_message)
msg (((flags & S_FATAL) ? M_FATAL : M_WARN), "%s: %s",
error_message,
system_error_message (stat, &gc));
}
gc_free (&gc);
return ret;
}
bool
openvpn_execve_allowed (const unsigned int flags)
{
if (flags & S_SCRIPT)
return script_security >= SSEC_SCRIPTS;
else
return script_security >= SSEC_BUILT_IN;
}
#ifndef WIN32
/*
* Run execve() inside a fork(). Designed to replicate the semantics of system() but
* in a safer way that doesn't require the invocation of a shell or the risks
* assocated with formatting and parsing a command line.
*/
int
openvpn_execve (const struct argv *a, const struct env_set *es, const unsigned int flags)
{
struct gc_arena gc = gc_new ();
int ret = -1;
static bool warn_shown = false;
if (a && a->argv[0])
{
#if defined(ENABLE_FEATURE_EXECVE)
if (openvpn_execve_allowed (flags))
{
const char *cmd = a->argv[0];
char *const *argv = a->argv;
char *const *envp = (char *const *)make_env_array (es, true, &gc);
pid_t pid;
pid = fork ();
if (pid == (pid_t)0) /* child side */
{
execve (cmd, argv, envp);
exit (127);
}
else if (pid < (pid_t)0) /* fork failed */
msg (M_ERR, "openvpn_execve: unable to fork");
else /* parent side */
{
if (waitpid (pid, &ret, 0) != pid)
ret = -1;
}
}
else if (!warn_shown && (script_security < SSEC_SCRIPTS))
{
msg (M_WARN, SCRIPT_SECURITY_WARNING);
warn_shown = true;
}
#else
msg (M_WARN, "openvpn_execve: execve function not available");
#endif
}
else
{
msg (M_FATAL, "openvpn_execve: called with empty argv");
}
gc_free (&gc);
return ret;
}
#endif
/*
* Run execve() inside a fork(), duping stdout. Designed to replicate the semantics of popen() but
* in a safer way that doesn't require the invocation of a shell or the risks
* assocated with formatting and parsing a command line.
*/
int
openvpn_popen (const struct argv *a, const struct env_set *es)
{
struct gc_arena gc = gc_new ();
int ret = -1;
static bool warn_shown = false;
if (a && a->argv[0])
{
#if defined(ENABLE_FEATURE_EXECVE)
if (script_security >= SSEC_BUILT_IN)
{
const char *cmd = a->argv[0];
char *const *argv = a->argv;
char *const *envp = (char *const *)make_env_array (es, true, &gc);
pid_t pid;
int pipe_stdout[2];
if (pipe (pipe_stdout) == 0) {
pid = fork ();
if (pid == (pid_t)0) /* child side */
{
close (pipe_stdout[0]);
dup2 (pipe_stdout[1],1);
execve (cmd, argv, envp);
exit (127);
}
else if (pid < (pid_t)0) /* fork failed */
{
msg (M_ERR, "openvpn_popen: unable to fork");
}
else /* parent side */
{
int status = 0;
waitpid(pid, &status, 0);
ret = pipe_stdout[0];
close (pipe_stdout[1]);
}
}
else {
msg (M_WARN, "openvpn_popen: unable to create stdout pipe");
ret = -1;
}
}
else if (!warn_shown && (script_security < SSEC_SCRIPTS))
{
msg (M_WARN, SCRIPT_SECURITY_WARNING);
warn_shown = true;
}
#else
msg (M_WARN, "openvpn_popen: execve function not available");
#endif
}
else
{
msg (M_FATAL, "openvpn_popen: called with empty argv");
}
gc_free (&gc);
return ret;
}
/*
* Initialize random number seed. random() is only used
* when "weak" random numbers are acceptable.
* OpenSSL routines are always used when cryptographically
* strong random numbers are required.
*/
void
init_random_seed(void)
{
struct timeval tv;
if (!gettimeofday (&tv, NULL))
{
const unsigned int seed = (unsigned int) tv.tv_sec ^ tv.tv_usec;
srandom (seed);
}
}
/* thread-safe strerror */
const char *
strerror_ts (int errnum, struct gc_arena *gc)
{
#ifdef HAVE_STRERROR
struct buffer out = alloc_buf_gc (256, gc);
buf_printf (&out, "%s", openvpn_strerror (errnum, gc));
return BSTR (&out);
#else
return "[error string unavailable]";
#endif
}
/*
* Set environmental variable (int or string).
*
* On Posix, we use putenv for portability,
* and put up with its painful semantics
* that require all the support code below.
*/
/* General-purpose environmental variable set functions */
static char *
construct_name_value (const char *name, const char *value, struct gc_arena *gc)
{
struct buffer out;
ASSERT (name);
if (!value)
value = "";
out = alloc_buf_gc (strlen (name) + strlen (value) + 2, gc);
buf_printf (&out, "%s=%s", name, value);
return BSTR (&out);
}
bool
deconstruct_name_value (const char *str, const char **name, const char **value, struct gc_arena *gc)
{
char *cp;
ASSERT (str);
ASSERT (name && value);
*name = cp = string_alloc (str, gc);
*value = NULL;
while ((*cp))
{
if (*cp == '=' && !*value)
{
*cp = 0;
*value = cp + 1;
}
++cp;
}
return *name && *value;
}
static bool
env_string_equal (const char *s1, const char *s2)
{
int c1, c2;
ASSERT (s1);
ASSERT (s2);
while (true)
{
c1 = *s1++;
c2 = *s2++;
if (c1 == '=')
c1 = 0;
if (c2 == '=')
c2 = 0;
if (!c1 && !c2)
return true;
if (c1 != c2)
break;
}
return false;
}
static bool
remove_env_item (const char *str, const bool do_free, struct env_item **list)
{
struct env_item *current, *prev;
ASSERT (str);
ASSERT (list);
for (current = *list, prev = NULL; current != NULL; current = current->next)
{
if (env_string_equal (current->string, str))
{
if (prev)
prev->next = current->next;
else
*list = current->next;
if (do_free)
{
memset (current->string, 0, strlen (current->string));
free (current->string);
free (current);
}
return true;
}
prev = current;
}
return false;
}
static void
add_env_item (char *str, const bool do_alloc, struct env_item **list, struct gc_arena *gc)
{
struct env_item *item;
ASSERT (str);
ASSERT (list);
ALLOC_OBJ_GC (item, struct env_item, gc);
item->string = do_alloc ? string_alloc (str, gc): str;
item->next = *list;
*list = item;
}
/* struct env_set functions */
static bool
env_set_del_nolock (struct env_set *es, const char *str)
{
return remove_env_item (str, es->gc == NULL, &es->list);
}
static void
env_set_add_nolock (struct env_set *es, const char *str)
{
remove_env_item (str, es->gc == NULL, &es->list);
add_env_item ((char *)str, true, &es->list, es->gc);
}
struct env_set *
env_set_create (struct gc_arena *gc)
{
struct env_set *es;
ALLOC_OBJ_CLEAR_GC (es, struct env_set, gc);
es->list = NULL;
es->gc = gc;
return es;
}
void
env_set_destroy (struct env_set *es)
{
if (es && es->gc == NULL)
{
struct env_item *e = es->list;
while (e)
{
struct env_item *next = e->next;
free (e->string);
free (e);
e = next;
}
free (es);
}
}
bool
env_set_del (struct env_set *es, const char *str)
{
bool ret;
ASSERT (es);
ASSERT (str);
ret = env_set_del_nolock (es, str);
return ret;
}
void
env_set_add (struct env_set *es, const char *str)
{
ASSERT (es);
ASSERT (str);
env_set_add_nolock (es, str);
}
void
env_set_print (int msglevel, const struct env_set *es)
{
if (check_debug_level (msglevel))
{
const struct env_item *e;
int i;
if (es)
{
e = es->list;
i = 0;
while (e)
{
if (env_safe_to_print (e->string))
msg (msglevel, "ENV [%d] '%s'", i, e->string);
++i;
e = e->next;
}
}
}
}
void
env_set_inherit (struct env_set *es, const struct env_set *src)
{
const struct env_item *e;
ASSERT (es);
if (src)
{
e = src->list;
while (e)
{
env_set_add_nolock (es, e->string);
e = e->next;
}
}
}
void
env_set_add_to_environment (const struct env_set *es)
{
if (es)
{
struct gc_arena gc = gc_new ();
const struct env_item *e;
e = es->list;
while (e)
{
const char *name;
const char *value;
if (deconstruct_name_value (e->string, &name, &value, &gc))
setenv_str (NULL, name, value);
e = e->next;
}
gc_free (&gc);
}
}
void
env_set_remove_from_environment (const struct env_set *es)
{
if (es)
{
struct gc_arena gc = gc_new ();
const struct env_item *e;
e = es->list;
while (e)
{
const char *name;
const char *value;
if (deconstruct_name_value (e->string, &name, &value, &gc))
setenv_del (NULL, name);
e = e->next;
}
gc_free (&gc);
}
}
#ifdef HAVE_PUTENV
/* companion functions to putenv */
static struct env_item *global_env = NULL; /* GLOBAL */
#endif
/* add/modify/delete environmental strings */
void
setenv_counter (struct env_set *es, const char *name, counter_type value)
{
char buf[64];
openvpn_snprintf (buf, sizeof(buf), counter_format, value);
setenv_str (es, name, buf);
}
void
setenv_int (struct env_set *es, const char *name, int value)
{
char buf[64];
openvpn_snprintf (buf, sizeof(buf), "%d", value);
setenv_str (es, name, buf);
}
void
setenv_unsigned (struct env_set *es, const char *name, unsigned int value)
{
char buf[64];
openvpn_snprintf (buf, sizeof(buf), "%u", value);
setenv_str (es, name, buf);
}
void
setenv_str (struct env_set *es, const char *name, const char *value)
{
setenv_str_ex (es, name, value, CC_NAME, 0, 0, CC_PRINT, 0, 0);
}
void
setenv_str_safe (struct env_set *es, const char *name, const char *value)
{
uint8_t b[64];
struct buffer buf;
buf_set_write (&buf, b, sizeof (b));
if (buf_printf (&buf, "OPENVPN_%s", name))
setenv_str (es, BSTR(&buf), value);
else
msg (M_WARN, "setenv_str_safe: name overflow");
}
void
setenv_del (struct env_set *es, const char *name)
{
ASSERT (name);
setenv_str (es, name, NULL);
}
void
setenv_str_ex (struct env_set *es,
const char *name,
const char *value,
const unsigned int name_include,
const unsigned int name_exclude,
const char name_replace,
const unsigned int value_include,
const unsigned int value_exclude,
const char value_replace)
{
struct gc_arena gc = gc_new ();
const char *name_tmp;
const char *val_tmp = NULL;
ASSERT (name && strlen (name) > 1);
name_tmp = string_mod_const (name, name_include, name_exclude, name_replace, &gc);
if (value)
val_tmp = string_mod_const (value, value_include, value_exclude, value_replace, &gc);
ASSERT (es);
if (val_tmp)
{
const char *str = construct_name_value (name_tmp, val_tmp, &gc);
env_set_add (es, str);
#if DEBUG_VERBOSE_SETENV
msg (M_INFO, "SETENV_ES '%s'", str);
#endif
}
else
env_set_del (es, name_tmp);
gc_free (&gc);
}
/*
* Setenv functions that append an integer index to the name
*/
static const char *
setenv_format_indexed_name (const char *name, const int i, struct gc_arena *gc)
{
struct buffer out = alloc_buf_gc (strlen (name) + 16, gc);
if (i >= 0)
buf_printf (&out, "%s_%d", name, i);
else
buf_printf (&out, "%s", name);
return BSTR (&out);
}
void
setenv_int_i (struct env_set *es, const char *name, const int value, const int i)
{
struct gc_arena gc = gc_new ();
const char *name_str = setenv_format_indexed_name (name, i, &gc);
setenv_int (es, name_str, value);
gc_free (&gc);
}
void
setenv_str_i (struct env_set *es, const char *name, const char *value, const int i)
{
struct gc_arena gc = gc_new ();
const char *name_str = setenv_format_indexed_name (name, i, &gc);
setenv_str (es, name_str, value);
gc_free (&gc);
}
/*
* taken from busybox networking/ifupdown.c
*/
unsigned int
count_bits(unsigned int a)
{
unsigned int result;
result = (a & 0x55) + ((a >> 1) & 0x55);
result = (result & 0x33) + ((result >> 2) & 0x33);
return((result & 0x0F) + ((result >> 4) & 0x0F));
}
int
count_netmask_bits(const char *dotted_quad)
{
unsigned int result, a, b, c, d;
/* Found a netmask... Check if it is dotted quad */
if (sscanf(dotted_quad, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
return -1;
result = count_bits(a);
result += count_bits(b);
result += count_bits(c);
result += count_bits(d);
return ((int)result);
}
/* return true if filename can be opened for read */
bool
test_file (const char *filename)
{
bool ret = false;
if (filename)
{
FILE *fp = platform_fopen (filename, "r");
if (fp)
{
fclose (fp);
ret = true;
}
else
{
if( openvpn_errno () == EACCES ) {
msg( M_WARN | M_ERRNO, "Could not access file '%s'", filename);
}
}
}
dmsg (D_TEST_FILE, "TEST FILE '%s' [%d]",
filename ? filename : "UNDEF",
ret);
return ret;
}
#ifdef ENABLE_CRYPTO
/* create a temporary filename in directory */
const char *
create_temp_file (const char *directory, const char *prefix, struct gc_arena *gc)
{
static unsigned int counter;
struct buffer fname = alloc_buf_gc (256, gc);
int fd;
const char *retfname = NULL;
unsigned int attempts = 0;
do
{
uint8_t rndbytes[16];
const char *rndstr;
++attempts;
++counter;
prng_bytes (rndbytes, sizeof rndbytes);
rndstr = format_hex_ex (rndbytes, sizeof rndbytes, 40, 0, NULL, gc);
buf_printf (&fname, PACKAGE "_%s_%s.tmp", prefix, rndstr);
retfname = gen_path (directory, BSTR (&fname), gc);
if (!retfname)
{
msg (M_FATAL, "Failed to create temporary filename and path");
return NULL;
}
/* Atomically create the file. Errors out if the file already
exists. */
fd = platform_open (retfname, O_CREAT | O_EXCL | O_WRONLY, S_IRUSR | S_IWUSR);
if (fd != -1)
{
close (fd);
return retfname;
}
else if (fd == -1 && errno != EEXIST)
{
/* Something else went wrong, no need to retry. */
struct gc_arena gcerr = gc_new ();
msg (M_FATAL, "Could not create temporary file '%s': %s",
retfname, strerror_ts (errno, &gcerr));
gc_free (&gcerr);
return NULL;
}
}
while (attempts < 6);
msg (M_FATAL, "Failed to create temporary file after %i attempts", attempts);
return NULL;
}
/*
* Prepend a random string to hostname to prevent DNS caching.
* For example, foo.bar.gov would be modified to <random-chars>.foo.bar.gov.
* Of course, this requires explicit support in the DNS server (wildcard).
*/
const char *
hostname_randomize(const char *hostname, struct gc_arena *gc)
{
# define n_rnd_bytes 6
uint8_t rnd_bytes[n_rnd_bytes];
const char *rnd_str;
struct buffer hname = alloc_buf_gc (strlen(hostname)+sizeof(rnd_bytes)*2+4, gc);
prng_bytes (rnd_bytes, sizeof (rnd_bytes));
rnd_str = format_hex_ex (rnd_bytes, sizeof (rnd_bytes), 40, 0, NULL, gc);
buf_printf(&hname, "%s.%s", rnd_str, hostname);
return BSTR(&hname);
# undef n_rnd_bytes
}
#else
const char *
hostname_randomize(const char *hostname, struct gc_arena *gc)
{
msg (M_WARN, "WARNING: hostname randomization disabled when crypto support is not compiled");
return hostname;
}
#endif
/*
* Put a directory and filename together.
*/
const char *
gen_path (const char *directory, const char *filename, struct gc_arena *gc)
{
#if WIN32
const int CC_PATH_RESERVED = CC_LESS_THAN|CC_GREATER_THAN|CC_COLON|
CC_DOUBLE_QUOTE|CC_SLASH|CC_BACKSLASH|CC_PIPE|CC_QUESTION_MARK|CC_ASTERISK;
#else
const int CC_PATH_RESERVED = CC_SLASH;
#endif
const char *safe_filename = string_mod_const (filename, CC_PRINT, CC_PATH_RESERVED, '_', gc);
if (safe_filename
&& strcmp (safe_filename, ".")
&& strcmp (safe_filename, "..")
#ifdef WIN32
&& win_safe_filename (safe_filename)
#endif
)
{
const size_t outsize = strlen(safe_filename) + (directory ? strlen (directory) : 0) + 16;
struct buffer out = alloc_buf_gc (outsize, gc);
char dirsep[2];
dirsep[0] = OS_SPECIFIC_DIRSEP;
dirsep[1] = '\0';
if (directory)
buf_printf (&out, "%s%s", directory, dirsep);
buf_printf (&out, "%s", safe_filename);