blob: 4be53c361ee19da598b090fbd1f85e0872e26c3f [file] [log] [blame]
/* dnsmasq is Copyright (c) 2000-2014 Simon Kelley
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 dated June, 1991, or
(at your option) version 3 dated 29 June, 2007.
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. If not, see <http://www.gnu.org/licenses/>.
*/
#include "dnsmasq.h"
#ifdef HAVE_SCRIPT
/* This file has code to fork a helper process which recieves data via a pipe
shared with the main process and which is responsible for calling a script when
DHCP leases change.
The helper process is forked before the main process drops root, so it retains root
privs to pass on to the script. For this reason it tries to be paranoid about
data received from the main process, in case that has been compromised. We don't
want the helper to give an attacker root. In particular, the script to be run is
not settable via the pipe, once the fork has taken place it is not alterable by the
main process.
*/
static void my_setenv(const char *name, const char *value, int *error);
static unsigned char *grab_extradata(unsigned char *buf, unsigned char *end, char *env, int *err);
#ifdef HAVE_LUASCRIPT
#define LUA_COMPAT_ALL
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#ifndef lua_open
#define lua_open() luaL_newstate()
#endif
lua_State *lua;
static unsigned char *grab_extradata_lua(unsigned char *buf, unsigned char *end, char *field);
#endif
struct script_data
{
int flags;
int action, hwaddr_len, hwaddr_type;
int clid_len, hostname_len, ed_len;
struct in_addr addr, giaddr;
unsigned int remaining_time;
#ifdef HAVE_BROKEN_RTC
unsigned int length;
#else
time_t expires;
#endif
#ifdef HAVE_TFTP
off_t file_len;
#endif
#ifdef HAVE_IPV6
struct in6_addr addr6;
#endif
#ifdef HAVE_DHCP6
int iaid, vendorclass_count;
#endif
unsigned char hwaddr[DHCP_CHADDR_MAX];
char interface[IF_NAMESIZE];
};
static struct script_data *buf = NULL;
static size_t bytes_in_buf = 0, buf_size = 0;
int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
{
pid_t pid;
int i, pipefd[2];
struct sigaction sigact;
/* create the pipe through which the main program sends us commands,
then fork our process. */
if (pipe(pipefd) == -1 || !fix_fd(pipefd[1]) || (pid = fork()) == -1)
{
send_event(err_fd, EVENT_PIPE_ERR, errno, NULL);
_exit(0);
}
if (pid != 0)
{
close(pipefd[0]); /* close reader side */
return pipefd[1];
}
/* ignore SIGTERM, so that we can clean up when the main process gets hit
and SIGALRM so that we can use sleep() */
sigact.sa_handler = SIG_IGN;
sigact.sa_flags = 0;
sigemptyset(&sigact.sa_mask);
sigaction(SIGTERM, &sigact, NULL);
sigaction(SIGALRM, &sigact, NULL);
if (!option_bool(OPT_DEBUG) && uid != 0)
{
gid_t dummy;
if (setgroups(0, &dummy) == -1 ||
setgid(gid) == -1 ||
setuid(uid) == -1)
{
if (option_bool(OPT_NO_FORK))
/* send error to daemon process if no-fork */
send_event(event_fd, EVENT_USER_ERR, errno, daemon->scriptuser);
else
{
/* kill daemon */
send_event(event_fd, EVENT_DIE, 0, NULL);
/* return error */
send_event(err_fd, EVENT_USER_ERR, errno, daemon->scriptuser);
}
_exit(0);
}
}
/* close all the sockets etc, we don't need them here.
Don't close err_fd, in case the lua-init fails.
Note that we have to do this before lua init
so we don't close any lua fds. */
for (max_fd--; max_fd >= 0; max_fd--)
if (max_fd != STDOUT_FILENO && max_fd != STDERR_FILENO &&
max_fd != STDIN_FILENO && max_fd != pipefd[0] &&
max_fd != event_fd && max_fd != err_fd)
close(max_fd);
#ifdef HAVE_LUASCRIPT
if (daemon->luascript)
{
const char *lua_err = NULL;
lua = lua_open();
luaL_openlibs(lua);
/* get Lua to load our script file */
if (luaL_dofile(lua, daemon->luascript) != 0)
lua_err = lua_tostring(lua, -1);
else
{
lua_getglobal(lua, "lease");
if (lua_type(lua, -1) != LUA_TFUNCTION)
lua_err = _("lease() function missing in Lua script");
}
if (lua_err)
{
if (option_bool(OPT_NO_FORK) || option_bool(OPT_DEBUG))
/* send error to daemon process if no-fork */
send_event(event_fd, EVENT_LUA_ERR, 0, (char *)lua_err);
else
{
/* kill daemon */
send_event(event_fd, EVENT_DIE, 0, NULL);
/* return error */
send_event(err_fd, EVENT_LUA_ERR, 0, (char *)lua_err);
}
_exit(0);
}
lua_pop(lua, 1); /* remove nil from stack */
lua_getglobal(lua, "init");
if (lua_type(lua, -1) == LUA_TFUNCTION)
lua_call(lua, 0, 0);
else
lua_pop(lua, 1); /* remove nil from stack */
}
#endif
/* All init done, close our copy of the error pipe, so that main process can return */
if (err_fd != -1)
close(err_fd);
/* loop here */
while(1)
{
struct script_data data;
char *p, *action_str, *hostname = NULL, *domain = NULL;
unsigned char *buf = (unsigned char *)daemon->namebuff;
unsigned char *end, *extradata, *alloc_buff = NULL;
int is6, err = 0;
free(alloc_buff);
/* we read zero bytes when pipe closed: this is our signal to exit */
if (!read_write(pipefd[0], (unsigned char *)&data, sizeof(data), 1))
{
#ifdef HAVE_LUASCRIPT
if (daemon->luascript)
{
lua_getglobal(lua, "shutdown");
if (lua_type(lua, -1) == LUA_TFUNCTION)
lua_call(lua, 0, 0);
}
#endif
_exit(0);
}
is6 = !!(data.flags & (LEASE_TA | LEASE_NA));
if (data.action == ACTION_DEL)
action_str = "del";
else if (data.action == ACTION_ADD)
action_str = "add";
else if (data.action == ACTION_OLD || data.action == ACTION_OLD_HOSTNAME)
action_str = "old";
else if (data.action == ACTION_TFTP)
{
action_str = "tftp";
is6 = (data.flags != AF_INET);
}
else
continue;
/* stringify MAC into dhcp_buff */
p = daemon->dhcp_buff;
if (data.hwaddr_type != ARPHRD_ETHER || data.hwaddr_len == 0)
p += sprintf(p, "%.2x-", data.hwaddr_type);
for (i = 0; (i < data.hwaddr_len) && (i < DHCP_CHADDR_MAX); i++)
{
p += sprintf(p, "%.2x", data.hwaddr[i]);
if (i != data.hwaddr_len - 1)
p += sprintf(p, ":");
}
/* supplied data may just exceed normal buffer (unlikely) */
if ((data.hostname_len + data.ed_len + data.clid_len) > MAXDNAME &&
!(alloc_buff = buf = malloc(data.hostname_len + data.ed_len + data.clid_len)))
continue;
if (!read_write(pipefd[0], buf,
data.hostname_len + data.ed_len + data.clid_len, 1))
continue;
/* CLID into packet */
for (p = daemon->packet, i = 0; i < data.clid_len; i++)
{
p += sprintf(p, "%.2x", buf[i]);
if (i != data.clid_len - 1)
p += sprintf(p, ":");
}
#ifdef HAVE_DHCP6
if (is6)
{
/* or IAID and server DUID for IPv6 */
sprintf(daemon->dhcp_buff3, "%s%u", data.flags & LEASE_TA ? "T" : "", data.iaid);
for (p = daemon->dhcp_packet.iov_base, i = 0; i < daemon->duid_len; i++)
{
p += sprintf(p, "%.2x", daemon->duid[i]);
if (i != daemon->duid_len - 1)
p += sprintf(p, ":");
}
}
#endif
buf += data.clid_len;
if (data.hostname_len != 0)
{
char *dot;
hostname = (char *)buf;
hostname[data.hostname_len - 1] = 0;
if (data.action != ACTION_TFTP)
{
if (!legal_hostname(hostname))
hostname = NULL;
else if ((dot = strchr(hostname, '.')))
{
domain = dot+1;
*dot = 0;
}
}
}
extradata = buf + data.hostname_len;
if (!is6)
inet_ntop(AF_INET, &data.addr, daemon->addrbuff, ADDRSTRLEN);
#ifdef HAVE_DHCP6
else
inet_ntop(AF_INET6, &data.addr6, daemon->addrbuff, ADDRSTRLEN);
#endif
#ifdef HAVE_TFTP
/* file length */
if (data.action == ACTION_TFTP)
sprintf(is6 ? daemon->packet : daemon->dhcp_buff, "%lu", (unsigned long)data.file_len);
#endif
#ifdef HAVE_LUASCRIPT
if (daemon->luascript)
{
if (data.action == ACTION_TFTP)
{
lua_getglobal(lua, "tftp");
if (lua_type(lua, -1) != LUA_TFUNCTION)
lua_pop(lua, 1); /* tftp function optional */
else
{
lua_pushstring(lua, action_str); /* arg1 - action */
lua_newtable(lua); /* arg2 - data table */
lua_pushstring(lua, daemon->addrbuff);
lua_setfield(lua, -2, "destination_address");
lua_pushstring(lua, hostname);
lua_setfield(lua, -2, "file_name");
lua_pushstring(lua, is6 ? daemon->packet : daemon->dhcp_buff);
lua_setfield(lua, -2, "file_size");
lua_call(lua, 2, 0); /* pass 2 values, expect 0 */
}
}
else
{
lua_getglobal(lua, "lease"); /* function to call */
lua_pushstring(lua, action_str); /* arg1 - action */
lua_newtable(lua); /* arg2 - data table */
if (is6)
{
lua_pushstring(lua, daemon->packet);
lua_setfield(lua, -2, "client_duid");
lua_pushstring(lua, daemon->dhcp_packet.iov_base);
lua_setfield(lua, -2, "server_duid");
lua_pushstring(lua, daemon->dhcp_buff3);
lua_setfield(lua, -2, "iaid");
}
if (!is6 && data.clid_len != 0)
{
lua_pushstring(lua, daemon->packet);
lua_setfield(lua, -2, "client_id");
}
if (strlen(data.interface) != 0)
{
lua_pushstring(lua, data.interface);
lua_setfield(lua, -2, "interface");
}
#ifdef HAVE_BROKEN_RTC
lua_pushnumber(lua, data.length);
lua_setfield(lua, -2, "lease_length");
#else
lua_pushnumber(lua, data.expires);
lua_setfield(lua, -2, "lease_expires");
#endif
if (hostname)
{
lua_pushstring(lua, hostname);
lua_setfield(lua, -2, "hostname");
}
if (domain)
{
lua_pushstring(lua, domain);
lua_setfield(lua, -2, "domain");
}
end = extradata + data.ed_len;
buf = extradata;
if (!is6)
buf = grab_extradata_lua(buf, end, "vendor_class");
#ifdef HAVE_DHCP6
else if (data.vendorclass_count != 0)
{
sprintf(daemon->dhcp_buff2, "vendor_class_id");
buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
for (i = 0; i < data.vendorclass_count - 1; i++)
{
sprintf(daemon->dhcp_buff2, "vendor_class%i", i);
buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
}
}
#endif
buf = grab_extradata_lua(buf, end, "supplied_hostname");
if (!is6)
{
buf = grab_extradata_lua(buf, end, "cpewan_oui");
buf = grab_extradata_lua(buf, end, "cpewan_serial");
buf = grab_extradata_lua(buf, end, "cpewan_class");
buf = grab_extradata_lua(buf, end, "circuit_id");
buf = grab_extradata_lua(buf, end, "subscriber_id");
buf = grab_extradata_lua(buf, end, "remote_id");
}
buf = grab_extradata_lua(buf, end, "tags");
if (is6)
buf = grab_extradata_lua(buf, end, "relay_address");
else if (data.giaddr.s_addr != 0)
{
lua_pushstring(lua, inet_ntoa(data.giaddr));
lua_setfield(lua, -2, "relay_address");
}
for (i = 0; buf; i++)
{
sprintf(daemon->dhcp_buff2, "user_class%i", i);
buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
}
if (data.action != ACTION_DEL && data.remaining_time != 0)
{
lua_pushnumber(lua, data.remaining_time);
lua_setfield(lua, -2, "time_remaining");
}
if (data.action == ACTION_OLD_HOSTNAME && hostname)
{
lua_pushstring(lua, hostname);
lua_setfield(lua, -2, "old_hostname");
}
if (!is6 || data.hwaddr_len != 0)
{
lua_pushstring(lua, daemon->dhcp_buff);
lua_setfield(lua, -2, "mac_address");
}
lua_pushstring(lua, daemon->addrbuff);
lua_setfield(lua, -2, "ip_address");
lua_call(lua, 2, 0); /* pass 2 values, expect 0 */
}
}
#endif
/* no script, just lua */
if (!daemon->lease_change_command)
continue;
/* possible fork errors are all temporary resource problems */
while ((pid = fork()) == -1 && (errno == EAGAIN || errno == ENOMEM))
sleep(2);
if (pid == -1)
continue;
/* wait for child to complete */
if (pid != 0)
{
/* reap our children's children, if necessary */
while (1)
{
int status;
pid_t rc = wait(&status);
if (rc == pid)
{
/* On error send event back to main process for logging */
if (WIFSIGNALED(status))
send_event(event_fd, EVENT_KILLED, WTERMSIG(status), NULL);
else if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
send_event(event_fd, EVENT_EXITED, WEXITSTATUS(status), NULL);
break;
}
if (rc == -1 && errno != EINTR)
break;
}
continue;
}
if (data.action != ACTION_TFTP)
{
#ifdef HAVE_DHCP6
my_setenv("DNSMASQ_IAID", is6 ? daemon->dhcp_buff3 : NULL, &err);
my_setenv("DNSMASQ_SERVER_DUID", is6 ? daemon->dhcp_packet.iov_base : NULL, &err);
my_setenv("DNSMASQ_MAC", is6 && data.hwaddr_len != 0 ? daemon->dhcp_buff : NULL, &err);
#endif
my_setenv("DNSMASQ_CLIENT_ID", !is6 && data.clid_len != 0 ? daemon->packet : NULL, &err);
my_setenv("DNSMASQ_INTERFACE", strlen(data.interface) != 0 ? data.interface : NULL, &err);
#ifdef HAVE_BROKEN_RTC
sprintf(daemon->dhcp_buff2, "%u", data.length);
my_setenv("DNSMASQ_LEASE_LENGTH", daemon->dhcp_buff2, &err);
#else
sprintf(daemon->dhcp_buff2, "%lu", (unsigned long)data.expires);
my_setenv("DNSMASQ_LEASE_EXPIRES", daemon->dhcp_buff2, &err);
#endif
my_setenv("DNSMASQ_DOMAIN", domain, &err);
end = extradata + data.ed_len;
buf = extradata;
if (!is6)
buf = grab_extradata(buf, end, "DNSMASQ_VENDOR_CLASS", &err);
#ifdef HAVE_DHCP6
else
{
if (data.vendorclass_count != 0)
{
buf = grab_extradata(buf, end, "DNSMASQ_VENDOR_CLASS_ID", &err);
for (i = 0; i < data.vendorclass_count - 1; i++)
{
sprintf(daemon->dhcp_buff2, "DNSMASQ_VENDOR_CLASS%i", i);
buf = grab_extradata(buf, end, daemon->dhcp_buff2, &err);
}
}
}
#endif
buf = grab_extradata(buf, end, "DNSMASQ_SUPPLIED_HOSTNAME", &err);
if (!is6)
{
buf = grab_extradata(buf, end, "DNSMASQ_CPEWAN_OUI", &err);
buf = grab_extradata(buf, end, "DNSMASQ_CPEWAN_SERIAL", &err);
buf = grab_extradata(buf, end, "DNSMASQ_CPEWAN_CLASS", &err);
buf = grab_extradata(buf, end, "DNSMASQ_CIRCUIT_ID", &err);
buf = grab_extradata(buf, end, "DNSMASQ_SUBSCRIBER_ID", &err);
buf = grab_extradata(buf, end, "DNSMASQ_REMOTE_ID", &err);
}
buf = grab_extradata(buf, end, "DNSMASQ_TAGS", &err);
if (is6)
buf = grab_extradata(buf, end, "DNSMASQ_RELAY_ADDRESS", &err);
else
my_setenv("DNSMASQ_RELAY_ADDRESS", data.giaddr.s_addr != 0 ? inet_ntoa(data.giaddr) : NULL, &err);
for (i = 0; buf; i++)
{
sprintf(daemon->dhcp_buff2, "DNSMASQ_USER_CLASS%i", i);
buf = grab_extradata(buf, end, daemon->dhcp_buff2, &err);
}
sprintf(daemon->dhcp_buff2, "%u", data.remaining_time);
my_setenv("DNSMASQ_TIME_REMAINING", data.action != ACTION_DEL && data.remaining_time != 0 ? daemon->dhcp_buff2 : NULL, &err);
my_setenv("DNSMASQ_OLD_HOSTNAME", data.action == ACTION_OLD_HOSTNAME ? hostname : NULL, &err);
if (data.action == ACTION_OLD_HOSTNAME)
hostname = NULL;
}
my_setenv("DNSMASQ_LOG_DHCP", option_bool(OPT_LOG_OPTS) ? "1" : NULL, &err);
/* we need to have the event_fd around if exec fails */
if ((i = fcntl(event_fd, F_GETFD)) != -1)
fcntl(event_fd, F_SETFD, i | FD_CLOEXEC);
close(pipefd[0]);
p = strrchr(daemon->lease_change_command, '/');
if (err == 0)
{
execl(daemon->lease_change_command,
p ? p+1 : daemon->lease_change_command,
action_str, is6 ? daemon->packet : daemon->dhcp_buff,
daemon->addrbuff, hostname, (char*)NULL);
err = errno;
}
/* failed, send event so the main process logs the problem */
send_event(event_fd, EVENT_EXEC_ERR, err, NULL);
_exit(0);
}
}
static void my_setenv(const char *name, const char *value, int *error)
{
if (*error == 0)
{
if (!value)
unsetenv(name);
else if (setenv(name, value, 1) != 0)
*error = errno;
}
}
static unsigned char *grab_extradata(unsigned char *buf, unsigned char *end, char *env, int *err)
{
unsigned char *next = NULL;
char *val = NULL;
if (buf && (buf != end))
{
for (next = buf; ; next++)
if (next == end)
{
next = NULL;
break;
}
else if (*next == 0)
break;
if (next && (next != buf))
{
char *p;
/* No "=" in value */
if ((p = strchr((char *)buf, '=')))
*p = 0;
val = (char *)buf;
}
}
my_setenv(env, val, err);
return next ? next + 1 : NULL;
}
#ifdef HAVE_LUASCRIPT
static unsigned char *grab_extradata_lua(unsigned char *buf, unsigned char *end, char *field)
{
unsigned char *next;
if (!buf || (buf == end))
return NULL;
for (next = buf; *next != 0; next++)
if (next == end)
return NULL;
if (next != buf)
{
lua_pushstring(lua, (char *)buf);
lua_setfield(lua, -2, field);
}
return next + 1;
}
#endif
static void buff_alloc(size_t size)
{
if (size > buf_size)
{
struct script_data *new;
/* start with reasonable size, will almost never need extending. */
if (size < sizeof(struct script_data) + 200)
size = sizeof(struct script_data) + 200;
if (!(new = whine_malloc(size)))
return;
if (buf)
free(buf);
buf = new;
buf_size = size;
}
}
/* pack up lease data into a buffer */
void queue_script(int action, struct dhcp_lease *lease, char *hostname, time_t now)
{
unsigned char *p;
unsigned int hostname_len = 0, clid_len = 0, ed_len = 0;
int fd = daemon->dhcpfd;
#ifdef HAVE_DHCP6
if (!daemon->dhcp)
fd = daemon->dhcp6fd;
#endif
/* no script */
if (daemon->helperfd == -1)
return;
if (lease->extradata)
ed_len = lease->extradata_len;
if (lease->clid)
clid_len = lease->clid_len;
if (hostname)
hostname_len = strlen(hostname) + 1;
buff_alloc(sizeof(struct script_data) + clid_len + ed_len + hostname_len);
buf->action = action;
buf->flags = lease->flags;
#ifdef HAVE_DHCP6
buf->vendorclass_count = lease->vendorclass_count;
buf->addr6 = lease->addr6;
buf->iaid = lease->iaid;
#endif
buf->hwaddr_len = lease->hwaddr_len;
buf->hwaddr_type = lease->hwaddr_type;
buf->clid_len = clid_len;
buf->ed_len = ed_len;
buf->hostname_len = hostname_len;
buf->addr = lease->addr;
buf->giaddr = lease->giaddr;
memcpy(buf->hwaddr, lease->hwaddr, DHCP_CHADDR_MAX);
if (!indextoname(fd, lease->last_interface, buf->interface))
buf->interface[0] = 0;
#ifdef HAVE_BROKEN_RTC
buf->length = lease->length;
#else
buf->expires = lease->expires;
#endif
if (lease->expires != 0)
buf->remaining_time = (unsigned int)difftime(lease->expires, now);
else
buf->remaining_time = 0;
p = (unsigned char *)(buf+1);
if (clid_len != 0)
{
memcpy(p, lease->clid, clid_len);
p += clid_len;
}
if (hostname_len != 0)
{
memcpy(p, hostname, hostname_len);
p += hostname_len;
}
if (ed_len != 0)
{
memcpy(p, lease->extradata, ed_len);
p += ed_len;
}
bytes_in_buf = p - (unsigned char *)buf;
}
#ifdef HAVE_TFTP
/* This nastily re-uses DHCP-fields for TFTP stuff */
void queue_tftp(off_t file_len, char *filename, union mysockaddr *peer)
{
unsigned int filename_len;
/* no script */
if (daemon->helperfd == -1)
return;
filename_len = strlen(filename) + 1;
buff_alloc(sizeof(struct script_data) + filename_len);
memset(buf, 0, sizeof(struct script_data));
buf->action = ACTION_TFTP;
buf->hostname_len = filename_len;
buf->file_len = file_len;
if ((buf->flags = peer->sa.sa_family) == AF_INET)
buf->addr = peer->in.sin_addr;
#ifdef HAVE_IPV6
else
buf->addr6 = peer->in6.sin6_addr;
#endif
memcpy((unsigned char *)(buf+1), filename, filename_len);
bytes_in_buf = sizeof(struct script_data) + filename_len;
}
#endif
int helper_buf_empty(void)
{
return bytes_in_buf == 0;
}
void helper_write(void)
{
ssize_t rc;
if (bytes_in_buf == 0)
return;
if ((rc = write(daemon->helperfd, buf, bytes_in_buf)) != -1)
{
if (bytes_in_buf != (size_t)rc)
memmove(buf, buf + rc, bytes_in_buf - rc);
bytes_in_buf -= rc;
}
else
{
if (errno == EAGAIN || errno == EINTR)
return;
bytes_in_buf = 0;
}
}
#endif