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Move ifchd files to a subdirectory.

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This commit is contained in:
Nicholas J. Kain
2010-11-12 04:51:49 -05:00
parent c999fee9f5
commit b42eeb8847
27 changed files with 19 additions and 115 deletions
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ifchd/CMakeLists.txt Normal file
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project (ifchd)
cmake_minimum_required (VERSION 2.6)
set(IFCHD_SRCS
ifchd.c
linux.c
strlist.c
signals.c
pidfile.c
chroot.c
nstrl.c
log.c
)
add_executable(ifchd ${IFCHD_SRCS})
#target_link_libraries(ifchd ncmlib)

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20040906
accept_conns() trivial correctness fix: EINTR return from accept should
force continue rather than break in handling loop.
fail_on_fdne() is now file_exists() with a slightly different API.
20040818
Use inet_aton rather than custom function; daemon.[ch] removed.
20040817
ifchd no longer logs a "FATAL - select returned an error!" when it
is -KILL'ed.
20040626
pending_exit is now static volatile sig_atomic_t rather than
static volatile int for pedantic correctness issues.
20040614
Added --interface (-i) option that allows one to restrict the
interfaces that ifchd clients are allowed to modify. I
reccomend that this flag be used to further mitigate the possible
effects of a compromised client. By default, all interfaces
may be modified by clients.
Minor cleanups.
Clear corresponding namesvrs and domains on socket disconnection.
20040613
Factor out Linux-specific code into linux.c.
Nameservers and search domains now tracked per-connection to
prevent races where a client could force a writeout of data
provided by another client.
Interface name now cleared on connection close.
Make all headers idempotent.
Minor improvements to error messages.
20040612
Removed iffd[] array; this change makes the state machine action
functions (perform_*) depend on less external state.
HOSTNAME command now supported; it is not enabled by default.
If you wish for remote daemons to be able to change the hostname
of the local machine, use the --hostname (-o) option.
20040610
Added MTU support.
20040609
Robustify so that suicide() isn't called at every possible failure.
Harmless failures will now simply print an error to the log. Risky
or severe errors still suicide().
20040608
Added support for resolv.conf, namely "nameserver" and "search" entries.
Make strlist more robust and paranoid.
20040607
Improved accept() code to be much more robust; it can now properly error
recover. I hope this will fix the elusive random-exit problem that
plagues machines running the 2.6 kernel.
Refactored dispatch_work() to be cleaner.

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Goals:
1. Security
a. Divide into seperate processes that each have the minimal
system access necessary to complete their task.
b. Use a well defined IPC mechanism to facilitate cooperation
between processes. In this case, UNIX domain sockets are
used, since they allow for UNIX DAC (on Linux, at least).
c. Write each program to be secure; don't rely on the
privilege seperations for security.
d. Simple error handling is favored rather than complex error
handling that may possibly be caused to "recover" in an
exploitable way.
e. Don't make stupid assumptions. Implement only the minimal
functionality necessary to perform a task. Expect brain
damaged or malicious inputs.
f. Run inside a chroot, with minimal privileges via
capabilities or MAC.
2. Reliability
a. Don't try to handle severe errors.
b. Log errors if program state is still sane.
c. Recover from predictable problems if necessary. Make sure
that recovery behavior is well understood and defined.
d. Complicated or unsafe recoveries should not be performed;
instead the program should promptly exit. Dead programs
don't cause exploits.
5. Portability
a. Portability is good, but portability may not be as wide as
a less secure program. Capabilities or MAC are not well
standardized, but remain necessary features.
b. Aside from the previous caveat, try to be as portable as
possible. At the very least, the dhcp client daemon
should be easily portable (only broadcast and perhaps RAW
packets are necessary).
98. Speed
a. If we aren't required to sacrifice anything more
important, it's always good to be fast.
99. Size
a. If we aren't required to sacrifice anything more
important, it's always good to be frugal.
Specifics:
Implementation language will be C. C is universally available, very
predictable, and well accepted. dhcp clients don't have to deal with
complicated data structures or extensively with strings, so C's
largest weaknesses should not be highly apparent. On the other hand,
dhcp clients must extensively deal with the OS in a low-level fashion.
C's strongest points will therefore be used.
More practically, a program written in a compiled language other than
C will be poorly accepted by the average user. Since widespread use
is an eventual goal of ndhc, this point is very eloquent.
For now, I'm taking advantage of the existing udhcpc. With minor
modifications, it will serve quite well as the dhcp client daemon. It
is then only necessary for me to write a client request translator
and a interface change daemon. The result should be a highly modular
solution.
I'm developing on a Linux-based platform. ndhc will first be designed
to work properly on a Linux-based system. I will then make certain
that ndhc works well on a RSBAC-enabled Linux system. Afterwards, I
_may_ spend some effort porting ndhc to FreeBSD (but don't count on it). I
have no personal interest in other platforms.
Layout:
ndhc daemon (root -> chroot -> drop all !(CAP_NET_BROADCAST|CAP_NET_RAW)
-> nopriv)
* handles dhcp protocol issues
* keeps track of leases
* talks to ndhif to perform tasks that require
higher privileges than CAP_NET_BROADCAST or CAP_NET_RAW
ifchd daemon (root -> openfd -> chroot -> drop all !CAP_NET_ADMIN -> nopriv)
* listens for interface change requests via UNIX domain socket
* restricts valid IP ranges that will be accepted
* performs interface changes
* keeps rw fds for system files (such as /etc/resolv.conf) that must
be modified outside the chroot

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GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA
Everyone is permitted to copy and distribute verbatim copies
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GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. This License applies to any program or other work which contains
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This section is intended to make thoroughly clear what is believed to
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certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
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NO WARRANTY
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OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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END OF TERMS AND CONDITIONS
Appendix: How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) 19yy <name of author>
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; either version 2 of the License, or
(at your option) any later version.
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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 19yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.

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ifchd, copyright (c) 2004 Nicholas Kain. Licensed under GNU GPL.
Requirements:
Linux kernel (tested: 2.4, 2.6)
* libcap is required (available via ftp.kernel.org)
C99-compliant C compiler (for C99 struct subobject init)
* any modern GCC should be sufficient
Tested with glibc 2.2.x and 2.3.x. dietlibc is not compatible. I have not yet
tested uclibc.
I may bother to port to other operating systems, but don't count on it. Other
OSes lack the functionality of a [RSBAC|SELinux]+PaX enabled kernel, so I find
them to be less useful for a highly secured system.
INTRODUCTION
------------
ndhc consists of a set of daemons that cooperate in order to provide
privilege-seperated dhcp client services. Each daemon runs with the minimal
necessary privileges in order to perform its task. Currently, ndhc consists of
two daemons: the eponymous ndhc and ifchd.
ndhc communicates with dhcp servers and handles the vagaries of the dhcp
client protocol. It runs as a non-root user inside a chroot. ndhc retains
only the minimum necessary set of privileges required to perform its duties.
These powers include the ability to bind to a low port, the ability to open a
raw socket, and the ability to communicate on broadcast channels. ndhc holds
no other powers and is restricted to a chroot that contains nothing more than a
domain socket filesystem object and (at least on Linux) a urandom device node.
ifchd handles interface change requests. It listens on a UNIX domain socket
for such requests, and denies any client that does not match an authorized gid,
uid, or pid. ifchd runs as a non-root user inside a chroot, and retains only
the power to configure network interfaces. ifchd is designed so that it has
the ability to service multiple client requests simultaneously; a single ifchd
is sufficient for multiple ndhc clients. Only exotic setups should require
this functionality, but it does exist.
Note that ndhc does not support the entire DHCP client protocol. Only the
minimum necessary featureset is implemented. This behavior should be familiar
to anyone who has used software that purports to be be secure.
Many of the features that ndhc depends upon are not entirely standard and vary
between UNIX systems. It is likely that some effort will be required in order
to port ndhc to new systems. The ndhc daemon should be entirely portable aside
from its use of Linux-style POSIX capabilities.
ifchd is necessarily less portable, since it must use system-specific ioctls in
order to configure network interfaces. Additionally, ifchd uses extensions to
the UNIX domain socket family to limit connections to user defined subsets of
possible uids, gids, and pids. These extensions are present in Linux and BSD,
although both Linux and BSD have different interfaces for the functionality.
Patches that provide support for new systems are welcome.
USAGE
-----
1) Compile and install ifchd and ndhc.
a) Build ifchd with "make"
b) Enter ndhc directory and build ndhc with "make"
c) Install the ifchd and ndhc executables in a normal place. I would
suggest /usr/sbin or /usr/local/sbin.
2) Time to create the jail in which ifchd and ndhc will run.
a) Become root and create new group "ifchd".
$ su -
# umask 077
# groupadd ifchd
b) Create new users "ifchd" and "dhcp". The primary group of these
users should be "ifchd".
# useradd -d /var/lib/ndhc -g ifchd ifchd
# useradd -d /var/lib/ndhc -g ifchd dhcp
b) Create the jail directory and set its ownership properly.
# mkdir /var/lib/ndhc
# chown ifchd.ifchd /var/lib/ndhc
# chmod a+rx /var/lib/ndhc
c) Create a urandom device for ndhc to use within the jail.
# cd /var/lib/ndhc
# mkdir dev
# mknod dev/urandom c 1 9
# chown -R root.root dev
# chmod a+rx dev
# chmod a+r dev/urandom
d) (optional) If you wish for logging to properly work, you
will need to properly configure your logging daemon so that it
opens a domain socket in the proper location within the jail.
Since this varies per-daemon, I cannot provide a general
configuration.
3) At this point the jail is usable; ifchd and ndhc are ready to
be used. As an example of a sample configuration, here is my
rc.dhcp:
--START--
#!/bin/sh
case "$1" in
start)
ifchd -i eth0 -p /var/run/ifchd.pid -u ifchd -g ifchd -U dhcp -G ifchd \
-c /var/lib/ndhc &> /dev/null
ndhc -b -i eth0 -u dhcp -C /var/lib/ndhc &> /dev/null
;;
stop)
killall ndhc ifchd
;;
esac
--END--
This script works fine with my personal machines, which are set up
exactly as I have outlined above. If you have not entirely followed my
directions, the script will of course require modifications.
4o) If you encounter problems, I suggest running both ifchd and ndhc in the
foreground, and perhaps compiling ndhc with extra debugging output
(uncomment DEBUG=1 in the Makefile).
BEHAVIOR NOTES
--------------
ifchd does not enable updates of the local hostname and resolv.conf by default.
If you wish to enable these functions, use the --resolve (-r) and --hostname
(-o) flags. See ifchd --help.
ifchd can be set such that it only allows clients to configure particular
network interfaces. The --interface (-i) argument does the trick, and may
be used multiple times to allow multiple interfaces.
RSBAC NOTES
-----------
I was personally unable to get ifchd to properly function with RSBAC_NET_DEV
enabled. Browsing the rsbac source, I was unable to figure out what I was
doing incorrectly -- my RC definitions were as far as I could tell, correct.
Therefore, my directions assume that you have disabled RSBAC_NET_DEV in your
kernel configuration.
The normal usage directions may be followed, but an additional step for rsbac
is necessary. Change to your secoff account and invoke rsbac_fd_menu on the
ifchd and ndhc executables. The AUTH capability for your ifchd and dhcp groups
must be allowed on the corresponding executables, otherwise ifchd and ndhc will
be unable to change to a non-root user and will refuse to run.
GRSECURITY NOTES
----------------
Make sure that CONFIG_GRKERNSEC_CHROOT_CAPS is disabled. Otherwise, ifchd will
lose its capabilities (in particular, the ability to reconfigure interfaces)
when it chroots.
PORTING NOTES
-------------
Unportable functions are isolated to linux.c. Any attempts to port ifchd to
other platforms should isolate platform-dependent code to similarly named
compilation units (eg: for FreeBSD, freebsd.[ch]).
There are four major functions that ifchd depends upon that are not generally
portable. First, it uses the SO_PEERCRED flag of getsockopt() to discriminate
authorized connections by uid, gid, and pid. Similar functionality exists in
at least the BSDs; however, it has a different API. Second, ifchd takes
advantage of Linux capabilities so that it does not need full root privileges.
Capabilities are supposedly a POSIX feature, but in practice, they vary greatly
from system to system. Third and fourth, ifchd configures network interfaces
and routes. Interface and route configuration is entirely non-portable,
usually requiring calls to the catch-all ioctl(), and will almost certainly
require platform-dependent code.
Some standard C libraries include a native implementation of strlcpy() and
strlcat(). Such defines may conflict with my implementations in
nstrl.c/nstrl.h. It is up to the user whether the standard C library
implementations should be used. Note that some machines implement strlcpy()
and strlcat() with nonstandard semantics (notably Solaris). On these systems,
using the system-provided implementations may lead to security problems. Such
problems are the fault of the vendor. If you are unsure whether your system is
correct or not, I suggest using the implementation that I provide.

3
ifchd/TODO Normal file
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@@ -0,0 +1,3 @@
write documentation...
support BSD

42
ifchd/chroot.c Normal file
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@@ -0,0 +1,42 @@
/* chroot.c - chroots ncron jobs
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include <unistd.h>
#include <stdlib.h>
#include "log.h"
void imprison(char *path)
{
int ret;
if (path == NULL)
return;
ret = chdir(path);
if (ret) {
log_line("Failed to chdir(%s). Not invoking job.", path);
exit(EXIT_FAILURE);
}
ret = chroot(path);
if (ret) {
log_line("Failed to chroot(%s). Not invoking job.", path);
exit(EXIT_FAILURE);
}
}

21
ifchd/chroot.h Normal file
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@@ -0,0 +1,21 @@
/* chroot.h - include file for chroot.c
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef NJK_CHROOT_H_
#define NJK_CHROOT_H_ 1
void imprison(char *path);
#endif

12
ifchd/defines.h Normal file
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@@ -0,0 +1,12 @@
#define MAX_PATH_LENGTH 1024
#define PID_FILE_DEFAULT "/var/run/ifchd.pid"
#define IFCHD_VERSION "0.8"
#define COMM_SOCKET_PATH "ifchange"
#define MAX_BUF 1024
#define MAXLINE 1024
#define SOCK_QUEUE 2
#define CONN_TIMEOUT 60
#define LINUX 1

948
ifchd/ifchd.c Normal file
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@@ -0,0 +1,948 @@
/* ifchd.c - interface change daemon
* Time-stamp: <2010-11-12 04:28:47 njk>
*
* (C) 2004 Nicholas J. Kain <njk@aerifal.cx>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <errno.h>
#define _GNU_SOURCE
#include <getopt.h>
#include "defines.h"
#include "log.h"
#include "chroot.h"
#include "pidfile.h"
#include "signals.h"
#include "strlist.h"
#include "ifproto.h"
#include "nstrl.h"
#include "linux.h"
enum states {
STATE_NOTHING,
STATE_INTERFACE,
STATE_IP,
STATE_SUBNET,
STATE_TIMEZONE,
STATE_ROUTER,
STATE_TIMESVR,
STATE_DNS,
STATE_LPRSVR,
STATE_HOSTNAME,
STATE_DOMAIN,
STATE_IPTTL,
STATE_MTU,
STATE_BROADCAST,
STATE_NTPSRV,
STATE_WINS
};
static volatile sig_atomic_t pending_exit;
/* Socket fd, current state, and idle time for connections. */
static int sks[SOCK_QUEUE], state[SOCK_QUEUE], idle_time[SOCK_QUEUE];
/* Per-connection buffers. */
static char ibuf[SOCK_QUEUE][MAX_BUF];
/*
* Per-connection pointers into the command lists. Respectively, the
* topmost item on the list, the current item, and the last item on the list.
*/
static strlist_t *head[SOCK_QUEUE], *curl[SOCK_QUEUE], *last[SOCK_QUEUE];
int resolv_conf_fd = -1;
/* int ntp_conf_fd = -1; */
/* If true, allow HOSTNAME changes from dhcp server. */
int allow_hostname = 0;
static uid_t peer_uid;
static gid_t peer_gid;
static pid_t peer_pid;
/* Lists of nameservers and search domains. Unfortunately they must be
* per-connection, since otherwise seperate clients could race against
* one another to write out unpredictable data.
*/
static strlist_t *namesvrs[SOCK_QUEUE];
static strlist_t *domains[SOCK_QUEUE];
static void sighandler(int sig) {
pending_exit = 1;
}
static void fix_signals(void) {
disable_signal(SIGPIPE);
disable_signal(SIGUSR1);
disable_signal(SIGUSR2);
disable_signal(SIGTSTP);
disable_signal(SIGTTIN);
disable_signal(SIGCHLD);
disable_signal(SIGHUP);
hook_signal(SIGINT, sighandler, 0);
hook_signal(SIGTERM, sighandler, 0);
}
static void suicide(char *errmsg, const char *perrmsg, int status)
{
if (errmsg)
log_line(errmsg);
if (!gflags_detach && perrmsg)
perror(perrmsg);
exit(status);
}
static void die_nulstr(strlist_t *p)
{
if (!p)
suicide("FATAL - NULL passed to die_nulstr\n", NULL, EXIT_FAILURE);
if (!p->str)
suicide("FATAL - NULL string in strlist\n", NULL, EXIT_FAILURE);
}
static void safe_write(int fd, const char *buf, int len)
{
ssize_t r;
retry:
r = write(fd, buf, len);
if (r != len) {
if (r == -1) {
if (errno == EINTR)
goto retry;
else
suicide("write returned error\n", NULL, EXIT_FAILURE);
} else {
len -= r;
goto retry;
}
}
}
/* Writes out each element in a strlist as an argument to a keyword in
* a file. */
static void write_resolve_list(const char *keyword, strlist_t *list)
{
char *buf;
strlist_t *p = list;
unsigned int len;
if (!keyword || resolv_conf_fd == -1)
return;
while (p) {
buf = p->str;
len = strlen(buf);
if (len) {
safe_write(resolv_conf_fd, keyword, strlen(keyword));
safe_write(resolv_conf_fd, buf, strlen(buf));
safe_write(resolv_conf_fd, "\n", 1);
}
p = p->next;
}
}
/* Writes a new resolv.conf based on the information we have received. */
static void write_resolve_conf(int idx)
{
int r;
off_t off;
if (resolv_conf_fd == -1)
return;
if (lseek(resolv_conf_fd, 0, SEEK_SET) == -1)
return;
write_resolve_list("nameserver ", namesvrs[idx]);
write_resolve_list("search ", domains[idx]);
off = lseek(resolv_conf_fd, 0, SEEK_CUR);
if (off == -1) {
log_line("write_resolve_conf: lseek returned error: %s\n",
strerror(errno));
return;
}
retry:
r = ftruncate(resolv_conf_fd, off);
if (r == -1) {
if (errno == EINTR)
goto retry;
log_line("write_resolve_conf: ftruncate returned error: %s\n",
strerror(errno));
return;
}
r = fsync(resolv_conf_fd);
if (r == -1) {
log_line("write_resolve_conf: fsync returned error: %s\n",
strerror(errno));
return;
}
}
/* Decomposes a ' '-delimited flat character array onto a strlist, then
* calls the given function to perform work on the generated strlist. */
static void parse_list(int idx, char *str, strlist_t **toplist,
void (*fn)(int))
{
char *p, n[256];
unsigned int i;
strlist_t *newn = 0;
if (!str || !toplist || !fn)
return;
p = str;
while (p != '\0') {
memset(n, '\0', sizeof n);
for (i = 0; i < sizeof n - 1 && *p != '\0' && *p != ' '; ++p, ++i)
n[i] = *p;
if (*p == ' ')
++p;
add_to_strlist(n, &newn);
}
if (newn) {
free_strlist(*toplist);
*toplist = newn;
} else
return;
(*fn)(idx);
}
/* XXX: addme */
static void perform_timezone(int idx, char *str)
{}
/* Does anyone use this command? */
static void perform_timesvr(int idx, char *str)
{}
/* Add a dns server to the /etc/resolv.conf -- we already have a fd. */
static void perform_dns(int idx, char *str)
{
if (!str || resolv_conf_fd == -1)
return;
parse_list(idx, str, &(namesvrs[idx]), &write_resolve_conf);
}
/* Updates for print daemons are too non-standard to be useful. */
static void perform_lprsvr(int idx, char *str)
{}
/* Sets machine hostname. */
static void perform_hostname(int idx, char *str)
{
if (!allow_hostname || !str)
return;
if (sethostname(str, strlen(str) + 1) == -1)
log_line("sethostname returned %s\n", strerror(errno));
}
/* update "search" in /etc/resolv.conf */
static void perform_domain(int idx, char *str)
{
if (!str || resolv_conf_fd == -1)
return;
parse_list(idx, str, &(domains[idx]), &write_resolve_conf);
}
/* I don't think this can be done without a netfilter extension
* that isn't in the mainline kernels. */
static void perform_ipttl(int idx, char *str)
{}
/* XXX: addme */
static void perform_ntpsrv(int idx, char *str)
{}
/* Maybe Samba cares about this feature? I don't know. */
static void perform_wins(int idx, char *str)
{}
/* Wipes all state associated with a given connection. */
static void new_sk(int idx, int val)
{
sks[idx] = val;
memset(ibuf[idx], '\0', sizeof(ibuf[idx]));
free_strlist(head[idx]);
free_strlist(namesvrs[idx]);
free_strlist(domains[idx]);
head[idx] = NULL;
curl[idx] = NULL;
last[idx] = NULL;
namesvrs[idx] = NULL;
domains[idx] = NULL;
idle_time[idx] = time(NULL);
state[idx] = STATE_NOTHING;
clear_if_data(idx);
}
/* Conditionally accepts a new connection and initializes data structures. */
static void add_sk(int sk)
{
int i;
if (authorized_peer(sk, peer_pid, peer_uid, peer_gid)) {
for (i=0; i<SOCK_QUEUE; i++)
if (sks[i] == -1) {
new_sk(i, sk);
return;
}
}
close(sk);
}
/* Closes idle connections. */
static void close_idle_sk(void)
{
int i;
for (i=0; i<SOCK_QUEUE; i++) {
if (sks[i] == -1)
continue;
if (time(NULL) - idle_time[i] > CONN_TIMEOUT) {
close(sks[i]);
new_sk(i, -1);
}
}
}
/* Decomposes a ':'-delimited flat character array onto a strlist. */
static int stream_onto_list(int i)
{
int e, s;
for (e = 0, s = 0; ibuf[i][e] != '\0'; e++) {
if (ibuf[i][e] == ':') {
/* Zero-length command: skip. */
if (s == e) {
s = e + 1;
continue;
}
curl[i] = malloc(sizeof(strlist_t));
if (curl[i] == NULL)
suicide("FATAL - malloc failed\n", "malloc",
EXIT_FAILURE);
if (head[i] == NULL) {
head[i] = curl[i];
last[i] = NULL;
}
curl[i]->next = NULL;
if (last[i] != NULL)
last[i]->next = curl[i];
curl[i]->str = malloc(e - s + 1);
if (curl[i]->str == NULL)
suicide("FATAL - malloc failed\n", "malloc",
EXIT_FAILURE);
strlcpy(curl[i]->str, ibuf[i] + s, e - s);
last[i] = curl[i];
s = e + 1;
}
}
return s;
}
/* State machine that runs over the command and argument list,
* executing commands. */
static void execute_list(int i)
{
char *p;
for (;;) {
if (!curl[i])
break;
die_nulstr(curl[i]);
p = curl[i]->str;
switch (state[i]) {
case STATE_NOTHING:
if (strncmp(p, CMD_INTERFACE, sizeof(CMD_INTERFACE)) == 0)
state[i] = STATE_INTERFACE;
if (strncmp(p, CMD_IP, sizeof(CMD_IP)) == 0)
state[i] = STATE_IP;
if (strncmp(p, CMD_SUBNET, sizeof(CMD_SUBNET)) == 0)
state[i] = STATE_SUBNET;
if (strncmp(p, CMD_TIMEZONE, sizeof(CMD_TIMEZONE)) == 0)
state[i] = STATE_TIMEZONE;
if (strncmp(p, CMD_ROUTER, sizeof(CMD_ROUTER)) == 0)
state[i] = STATE_ROUTER;
if (strncmp(p, CMD_TIMESVR, sizeof(CMD_TIMESVR)) == 0)
state[i] = STATE_TIMESVR;
if (strncmp(p, CMD_DNS, sizeof(CMD_DNS)) == 0)
state[i] = STATE_DNS;
if (strncmp(p, CMD_LPRSVR, sizeof(CMD_LPRSVR)) == 0)
state[i] = STATE_LPRSVR;
if (strncmp(p, CMD_HOSTNAME, sizeof(CMD_HOSTNAME)) == 0)
state[i] = STATE_HOSTNAME;
if (strncmp(p, CMD_DOMAIN, sizeof(CMD_DOMAIN)) == 0)
state[i] = STATE_DOMAIN;
if (strncmp(p, CMD_IPTTL, sizeof(CMD_IPTTL)) == 0)
state[i] = STATE_IPTTL;
if (strncmp(p, CMD_MTU, sizeof(CMD_MTU)) == 0)
state[i] = STATE_MTU;
if (strncmp(p, CMD_BROADCAST, sizeof(CMD_BROADCAST)) == 0)
state[i] = STATE_BROADCAST;
if (strncmp(p, CMD_NTPSRV, sizeof(CMD_NTPSRV)) == 0)
state[i] = STATE_NTPSRV;
if (strncmp(p, CMD_WINS, sizeof(CMD_WINS)) == 0)
state[i] = STATE_WINS;
free_stritem(&(curl[i]));
break;
case STATE_INTERFACE:
perform_interface(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_IP:
perform_ip(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_SUBNET:
perform_subnet(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_TIMEZONE:
perform_timezone(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_ROUTER:
perform_router(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_TIMESVR:
perform_timesvr(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_DNS:
perform_dns(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_LPRSVR:
perform_lprsvr(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_HOSTNAME:
perform_hostname(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_DOMAIN:
perform_domain(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_IPTTL:
perform_ipttl(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_MTU:
perform_mtu(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_BROADCAST:
perform_broadcast(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_NTPSRV:
perform_ntpsrv(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
case STATE_WINS:
perform_wins(i, p);
free_stritem(&(curl[i]));
state[i] = STATE_NOTHING;
break;
default:
log_line("warning: invalid state in dispatch_work\n");
break;
}
}
head[i] = curl[i];
}
/* Opens a non-blocking listening socket with the appropriate properties. */
static int get_listen(void)
{
int lsock, ret;
struct sockaddr_un lsock_addr =
{
.sun_family = AF_UNIX,
.sun_path = COMM_SOCKET_PATH
};
lsock = socket(PF_UNIX, SOCK_STREAM, 0);
if (lsock == -1)
suicide("FATAL - failed to create socket\n",
"dispatch_work - socket", EXIT_FAILURE);
fcntl(lsock, F_SETFL, O_NONBLOCK);
(void) unlink(COMM_SOCKET_PATH);
ret = bind(lsock, (struct sockaddr *) &lsock_addr, sizeof(lsock_addr));
if (ret)
suicide("FATAL - failed to bind socket\n",
"dispatch_work - bind", EXIT_FAILURE);
ret = chmod(COMM_SOCKET_PATH, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
if (ret)
suicide("FATAL - failed to chmod socket\n",
"dispatch_work - chmod", EXIT_FAILURE);
ret = listen(lsock, SOCK_QUEUE);
if (ret)
suicide("FATAL - failed to listen on socket\n",
"dispatch_work - listen", EXIT_FAILURE);
return lsock;
}
/* Abstracts away the details of accept()ing a socket connection. */
static void accept_conns(int *lsock)
{
int ret;
struct sockaddr_un sock_addr;
socklen_t sock_len = sizeof(sock_addr);
for(;;)
{
ret = accept(*lsock, (struct sockaddr *) &sock_addr, &sock_len);
if (ret != -1) {
add_sk(ret);
return;
}
switch (errno) {
case EAGAIN:
#ifdef LINUX
case ENETDOWN:
case EPROTO:
case ENOPROTOOPT:
case EHOSTDOWN:
case ENONET:
case EHOSTUNREACH:
case EOPNOTSUPP:
case ENETUNREACH:
#endif
return;
case EINTR:
continue;
case EBADF:
case ENOTSOCK:
case EINVAL:
log_line("warning: accept returned %s!\n", strerror(errno));
close(*lsock);
*lsock = get_listen();
return;
case ECONNABORTED:
case EMFILE:
case ENFILE:
log_line("warning: accept returned %s!\n", strerror(errno));
return;
default:
log_line("warning: accept returned a mysterious error: %s\n",
strerror(errno));
return;
}
}
}
/* Core function that handles connections, gathers input, and calls
* the state machine to do actual work. */
static void dispatch_work(void)
{
int lsock, ret, highfd, i, index;
fd_set rfds;
char buf[MAX_BUF];
/* Initialize all structures to blank state. */
for (i=0; i<SOCK_QUEUE; i++)
sks[i] = -1;
initialize_if_data();
lsock = get_listen();
for (;;) {
FD_ZERO(&rfds);
FD_SET(lsock, &rfds);
/* find highest fd */
for (i=0, highfd=0; i<SOCK_QUEUE; i++) {
if (sks[i] != -1) {
FD_SET(sks[i], &rfds);
if (sks[i] > highfd)
highfd = sks[i];
}
}
if (lsock > highfd)
highfd = lsock;
ret = select(highfd + 1, &rfds, NULL, NULL, NULL);
switch (ret) {
case 0:
close_idle_sk();
break;
case -1:
if (pending_exit == 1)
return;
suicide("FATAL - select returned an error!\n",
"dispatch_work - select", EXIT_FAILURE);
break;
}
if (pending_exit == 1)
return;
/* handle pending connections */
if (FD_ISSET(lsock, &rfds))
accept_conns(&lsock);
/* Read in and process data on waiting connections */
for (i=0; i<SOCK_QUEUE; i++) {
if (sks[i] == -1)
continue;
if (!FD_ISSET(sks[i], &rfds))
continue;
idle_time[i] = time(NULL);
memset(buf, '\0', sizeof(buf));
dispatch_work_read_again:
ret = (int) read(sks[i], buf, MAX_BUF / 2 - 1);
/* Check to see if peer closed socket */
if (ret == 0) {
close(sks[i]);
new_sk(i, -1);
continue;
}
if (ret == -1) {
if (errno == EINTR)
goto dispatch_work_read_again;
log_line("dispatch_work: read returned %s.\n", strerror(errno));
close(sks[i]);
new_sk(i, -1);
continue;
}
/* Discard everything and close connection if we risk overflow.
* This approach is maximally conservative... worst case is that
* some client requests will get dropped. */
index = strlen(ibuf[i]);
if (index + strlen(buf) > MAX_BUF - 2) {
close(sks[i]);
new_sk(i, -1);
continue;
}
/* Append new stream input avoiding overflow. */
strlcpy(ibuf[i] + index, buf, sizeof(ibuf[i]) - index - 1);
/* Decompose ibuf contents onto strlist. */
index = stream_onto_list(i);
/* Remove everything that we've parsed into the list. */
strlcpy(buf, ibuf[i] + index, sizeof(buf));
strlcpy(ibuf[i], buf, sizeof(ibuf[i]));
/* Now we have a strlist of commands and arguments.
* Decompose and execute it. */
if (!head[i])
continue;
curl[i] = head[i];
execute_list(i);
}
close_idle_sk();
}
}
int main(int argc, char** argv) {
int c, t, uid = 0, gid = 0;
char pidfile[MAX_PATH_LENGTH] = PID_FILE_DEFAULT;
char chrootd[MAX_PATH_LENGTH] = "";
char resolv_conf_d[MAX_PATH_LENGTH] = "";
char *p;
struct passwd *pws;
struct group *grp;
while (1) {
int option_index = 0;
static struct option long_options[] = {
{"detach", 0, 0, 'd'},
{"nodetach", 0, 0, 'n'},
{"pidfile", 1, 0, 'p'},
{"quiet", 0, 0, 'q'},
{"chroot", 1, 0, 'c'},
{"resolve", 1, 0, 'r'},
{"hostname", 0, 0, 'o'},
{"user", 1, 0, 'u'},
{"group", 1, 0, 'g'},
{"cuser", 1, 0, 'U'},
{"cgroup", 1, 0, 'G'},
{"cpid", 1, 0, 'P'},
{"interface", 1, 0, 'i'},
{"help", 0, 0, 'h'},
{"version", 0, 0, 'v'},
{0, 0, 0, 0}
};
c = getopt_long(argc, argv, "dnp:qc:r:ou:g:U:G:P:i:hv", long_options,
&option_index);
if (c == -1)
break;
switch (c) {
case 'h':
printf(
"ifchd %s, if change daemon. Licensed under GNU GPL.\n", IFCHD_VERSION);
printf(
"Copyright (C) 2004 Nicholas J. Kain\n"
"Usage: ifchd [OPTIONS]\n"
" -d, --detach detach from TTY and daemonize\n"
" -n, --nodetach stay attached to TTY\n"
" -q, --quiet don't print to std(out|err) or log\n"
" -c, --chroot path where ifchd should chroot\n"
" -r, --resolve path to resolv.conf or equiv\n"
" -o, --hostname allow dhcp to set machine hostname\n"
" -p, --pidfile pidfile path\n");
printf(
" -u, --user user name that ifchd should run as\n"
" -g, --group group name that ifchd should run as\n"
" -U, --cuser user name of clients\n"
" -G, --cgroup group name of clients\n"
" -P, --cpid process id of client\n"
" -i, --interface ifchd clients may modify this interface\n"
" -h, --help print this help and exit\n"
" -v, --version print version information and exit\n");
exit(EXIT_FAILURE);
break;
case 'v':
printf(
"ifchd %s, if change daemon. Licensed under GNU GPL.\n", IFCHD_VERSION);
printf(
"Copyright (C) 2004 Nicholas J. Kain\n"
"This is free software; see the source for copying conditions. There is NO\n"
"WARRANTY; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n");
exit(EXIT_FAILURE);
break;
case 'd':
gflags_detach = 1;
break;
case 'n':
gflags_detach = 0;
break;
case 'q':
gflags_quiet = 1;
break;
case 'c':
strlcpy(chrootd, optarg, MAX_PATH_LENGTH);
break;
case 'p':
strlcpy(pidfile, optarg, MAX_PATH_LENGTH);
break;
case 'r':
strlcpy(resolv_conf_d, optarg, MAX_PATH_LENGTH);
break;
case 'o':
allow_hostname = 1;
break;
case 'u':
t = (unsigned int) strtol(optarg, &p, 10);
if (*p != '\0') {
pws = getpwnam(optarg);
if (pws) {
uid = (int)pws->pw_uid;
if (!gid)
gid = (int)pws->pw_gid;
} else suicide("FATAL - Invalid uid specified.\n", NULL,
EXIT_FAILURE);
} else
uid = t;
break;
case 'g':
t = (unsigned int) strtol(optarg, &p, 10);
if (*p != '\0') {
grp = getgrnam(optarg);
if (grp) {
gid = (int)grp->gr_gid;
} else suicide("FATAL - Invalid gid specified.\n", NULL,
EXIT_FAILURE);
} else
gid = t;
break;
case 'U':
t = (unsigned int) strtol(optarg, &p, 10);
if (*p != '\0') {
pws = getpwnam(optarg);
if (pws) {
peer_uid = (int)pws->pw_uid;
if (!peer_gid)
peer_gid = (int)pws->pw_gid;
} else suicide("FATAL - Invalid uid specified.\n", NULL,
EXIT_FAILURE);
} else
peer_uid = t;
break;
case 'G':
t = (unsigned int) strtol(optarg, &p, 10);
if (*p != '\0') {
grp = getgrnam(optarg);
if (grp) {
peer_gid = (int)grp->gr_gid;
} else suicide("FATAL - Invalid gid specified.\n", NULL,
EXIT_FAILURE);
} else
peer_gid = t;
break;
case 'P':
t = (unsigned int) strtol(optarg, &p, 10);
if (*p == '\0')
peer_pid = t;
break;
case 'i':
add_permitted_if(optarg);
break;
}
}
if (getuid())
suicide("FATAL - I need root for CAP_NET_ADMIN and chroot!\n",
NULL, EXIT_FAILURE);
if (gflags_detach)
if (daemon(0,0)) {
log_line("FATAL - detaching fork failed\n");
exit(EXIT_FAILURE);
}
if (!file_exists(pidfile, "w")) {
log_line("FATAL - cannot open pidfile for write!");
exit(EXIT_FAILURE);
}
write_pid(pidfile);
umask(077);
fix_signals();
/* If we are requested to update resolv.conf, preopen the fd before
* we drop root privileges, making sure that if we create
* resolv.conf, it will be world-readable.
*/
if (strncmp(resolv_conf_d, "", MAX_PATH_LENGTH)) {
umask(022);
resolv_conf_fd = open(resolv_conf_d, O_RDWR | O_CREAT, 644);
umask(077);
if (resolv_conf_fd == -1) {
suicide("FATAL - unable to open resolv.conf\n",
"main - open", EXIT_FAILURE);
}
}
if (!strncmp(chrootd, "", MAX_PATH_LENGTH))
suicide("FATAL - No chroot path specified. Refusing to run.\n",
NULL, EXIT_FAILURE);
/* Note that failure cases are handled by called fns. */
imprison(chrootd);
drop_root(uid, gid, "cap_net_admin=ep");
/* Cover our tracks... */
memset(chrootd, '\0', sizeof(chrootd));
memset(resolv_conf_d, '\0', sizeof(resolv_conf_d));
memset(pidfile, '\0', sizeof(pidfile));
dispatch_work();
/* Explicitly freed so memory debugger output has less static. */
for (c=0; c<SOCK_QUEUE; ++c) {
free_strlist(head[c]);
free_strlist(namesvrs[c]);
free_strlist(domains[c]);
}
exit(EXIT_SUCCESS);
}

20
ifchd/ifproto.h Normal file
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@@ -0,0 +1,20 @@
#ifndef NJK_IFPROTO_H__
#define NJK_IFPROTO_H__ 1
#define CMD_INTERFACE "interface"
#define CMD_IP "ip"
#define CMD_SUBNET "subnet"
#define CMD_TIMEZONE "timezone"
#define CMD_ROUTER "router"
#define CMD_TIMESVR "timesvr"
#define CMD_DNS "dns"
#define CMD_LPRSVR "lprsvr"
#define CMD_HOSTNAME "hostname"
#define CMD_DOMAIN "domain"
#define CMD_IPTTL "ipttl"
#define CMD_MTU "mtu"
#define CMD_BROADCAST "broadcast"
#define CMD_NTPSRV "ntpsrv"
#define CMD_WINS "wins"
#endif

394
ifchd/linux.c Normal file
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@@ -0,0 +1,394 @@
/* linux.c - ifchd Linux-specific functions
* Time-stamp: <2004-06-14 njk>
*
* (C) 2004 Nicholas J. Kain <njk@aerifal.cx>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define __USE_GNU 1
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/types.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/route.h>
#include <net/if.h>
#include <netpacket/packet.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include "defines.h"
#include "log.h"
#include "strlist.h"
#include "ifproto.h"
#include "nstrl.h"
/* Symbolic name of the interface associated with a connection. */
static char ifnam[SOCK_QUEUE][IFNAMSIZ];
static strlist_t *okif;
/* Clear a specified ifnam structure. */
void clear_if_data(int idx)
{
memset(ifnam[idx], '\0', IFNAMSIZ);
}
/* Clear all ifnam structures. */
void initialize_if_data(void)
{
int i;
for (i = 0; i < SOCK_QUEUE; i++) {
clear_if_data(i);
}
}
/* Adds to the list of interface names ifchd clients are allowed to change. */
void add_permitted_if(char *s)
{
if (!s)
return;
add_to_strlist(s, &okif);
}
/* Checks if changes are permitted to a given interface. 1 == allowed */
static int is_permitted(char *name)
{
strlist_t *p;
/* If empty, permit all. */
if (!okif)
return 1;
if (!name || strlen(name) == 0)
return 0;
p = okif;
while (p) {
if (strcmp(name, p->str) == 0)
return 1;
p = p->next;
}
log_line("attempt to modify interface %s denied\n", name);
return 0;
}
/* Verify that peer is authorized to connect (return 1 on success). */
int authorized_peer(int sk, pid_t pid, uid_t uid, gid_t gid)
{
int ret = 0;
unsigned int cl;
struct ucred cr;
/* No credentials to verify. */
if ( !(pid || uid || gid) )
return 1;
/* Verify that peer has authorized uid/gid/pid. */
cl = sizeof(struct ucred);
if (getsockopt(sk, SOL_SOCKET, SO_PEERCRED, &cr, &cl) != -1) {
if ((pid == 0 || cr.pid == pid) ||
(uid == 0 || cr.uid == uid) ||
(gid == 0 || cr.gid == gid))
ret = 1;
} else
log_line("getsockopt returned an error: %s\n", strerror(errno));
return ret;
}
void perform_interface(int idx, char *str)
{
if (!str)
return;
/* Update interface name. */
memset(ifnam[idx], '\0', IFNAMSIZ);
strlcpy(ifnam[idx], str, IFNAMSIZ);
}
static int set_if_flag(int idx, short flag)
{
int fd, ret = -1;
struct ifreq ifrt;
if (!is_permitted(ifnam[idx]))
goto out0;
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (set_if_flag) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
goto out0;
}
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
if (ioctl(fd, SIOCGIFFLAGS, &ifrt) < 0) {
log_line("%s: unknown interface: %s\n", ifnam[idx], strerror(errno));
goto out1;
}
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
ifrt.ifr_flags |= flag;
if (ioctl(fd, SIOCSIFFLAGS, &ifrt) < 0) {
log_line("%s: failed to set interface flags: %s\n",
ifnam[idx], strerror(errno));
goto out1;
}
ret = 0;
out1:
close(fd);
out0:
return ret;
}
/* Sets IP address on an interface and brings it up. */
void perform_ip(int idx, char *str)
{
int fd;
struct in_addr ipaddr;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_aton(str, &ipaddr))
return;
if (set_if_flag(idx, (IFF_UP | IFF_RUNNING)))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = ipaddr;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_ip) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFADDR, &ifrt) < 0)
log_line("%s: failed to configure IP: %s\n",
ifnam[idx], strerror(errno));
close(fd);
}
/* Sets the subnet mask on an interface. */
void perform_subnet(int idx, char *str)
{
int fd;
struct in_addr subnet;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_aton(str, &subnet))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = subnet;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_ip) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFNETMASK, &ifrt) < 0) {
sin.sin_addr.s_addr = 0xffffffff;
if (ioctl(fd, SIOCSIFNETMASK, &ifrt) < 0)
log_line("%s: failed to configure subnet: %s\n",
ifnam[idx], strerror(errno));
}
close(fd);
}
void perform_router(int idx, char *str)
{
struct rtentry rt;
struct sockaddr_in *dest;
struct sockaddr_in *gateway;
struct sockaddr_in *mask;
struct in_addr router;
int fd;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_aton(str, &router))
return;
memset(&rt, 0, sizeof(struct rtentry));
dest = (struct sockaddr_in *) &rt.rt_dst;
dest->sin_family = AF_INET;
dest->sin_addr.s_addr = 0x00000000;
gateway = (struct sockaddr_in *) &rt.rt_gateway;
gateway->sin_family = AF_INET;
gateway->sin_addr = router;
mask = (struct sockaddr_in *) &rt.rt_genmask;
mask->sin_family = AF_INET;
mask->sin_addr.s_addr = 0x00000000;
rt.rt_flags = RTF_UP | RTF_GATEWAY;
if (mask->sin_addr.s_addr == 0xffffffff) rt.rt_flags |= RTF_HOST;
rt.rt_dev = ifnam[idx];
rt.rt_metric = 1;
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_router) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCADDRT, &rt))
log_line("%s: failed to set route: %s\n", ifnam[idx], strerror(errno));
close(fd);
}
void perform_mtu(int idx, char *str)
{
int fd;
unsigned int mtu;
struct ifreq ifrt;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
mtu = strtol(str, NULL, 10);
ifrt.ifr_mtu = mtu;
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_mtu) failed to open interface socket: %s\n",
ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFMTU, &ifrt) < 0)
log_line("%s: failed to set MTU (%d): %s\n", ifnam[idx], mtu,
strerror(errno));
close(fd);
}
void perform_broadcast(int idx, char *str)
{
int fd;
struct in_addr broadcast;
struct ifreq ifrt;
struct sockaddr_in sin;
if (!str)
return;
if (!is_permitted(ifnam[idx]))
return;
if (!inet_aton(str, &broadcast))
return;
strlcpy(ifrt.ifr_name, ifnam[idx], IFNAMSIZ);
memset(&sin, 0, sizeof(struct sockaddr));
sin.sin_family = AF_INET;
sin.sin_addr = broadcast;
memcpy(&ifrt.ifr_addr, &sin, sizeof(struct sockaddr));
fd = socket(PF_INET, SOCK_DGRAM, 0);
if (fd == -1) {
log_line("%s: (perform_broadcast) failed to open interface socket: %s\n", ifnam[idx], strerror(errno));
return;
}
if (ioctl(fd, SIOCSIFBRDADDR, &ifrt) < 0)
log_line("%s: failed to set broadcast: %s\n",
ifnam[idx], strerror(errno));
close(fd);
}
static void set_cap(uid_t uid, gid_t gid, char *captxt)
{
cap_t caps;
if (!captxt) {
log_line("FATAL - set_cap: captxt == NULL\n");
exit(EXIT_FAILURE);
}
if (prctl(PR_SET_KEEPCAPS, 1)) {
log_line("FATAL - set_cap: prctl() failed\n");
exit(EXIT_FAILURE);
}
if (setgroups(0, NULL) == -1) {
log_line("FATAL - set_cap: setgroups() failed\n");
exit(EXIT_FAILURE);
}
if (setegid(gid) == -1 || seteuid(uid) == -1) {
log_line("FATAL - set_cap: seteuid() failed\n");
exit(EXIT_FAILURE);
}
caps = cap_from_text(captxt);
if (!caps) {
log_line("FATAL - set_cap: cap_from_text() failed\n");
exit(EXIT_FAILURE);
}
if (cap_set_proc(caps) == -1) {
log_line("FATAL - set_cap: cap_set_proc() failed\n");
exit(EXIT_FAILURE);
}
cap_free(caps);
}
void drop_root(uid_t uid, gid_t gid, char *captxt)
{
if (!captxt) {
log_line("FATAL - drop_root: captxt == NULL\n");
exit(EXIT_FAILURE);
}
if (uid == 0 || gid == 0) {
log_line("FATAL - drop_root: attempt to drop root to root?\n");
exit(EXIT_FAILURE);
}
set_cap(uid, gid, captxt);
if (setregid(gid, gid) == -1 || setreuid(uid, uid) == -1) {
log_line("FATAL - drop_root: failed to drop root!\n");
exit(EXIT_FAILURE);
}
}

36
ifchd/linux.h Normal file
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@@ -0,0 +1,36 @@
/* linux.h - ifchd Linux-specific functions include
* Time-stamp: <2004-06-13 njk>
*
* (C) 2004 Nicholas J. Kain <njk@aerifal.cx>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#ifndef NJK_IFCHD_LINUX_H_
#define NJK_IFCHD_LINUX_H_ 1
void clear_if_data(int idx);
void initialize_if_data(void);
void add_permitted_if(char *s);
int authorized_peer(int sk, pid_t pid, uid_t uid, gid_t gid);
void perform_interface(int idx, char *str);
void perform_ip(int idx, char *str);
void perform_subnet(int idx, char *str);
void perform_router(int idx, char *str);
void perform_mtu(int idx, char *str);
void perform_broadcast(int idx, char *str);
void drop_root(uid_t uid, gid_t gid, char *captxt);
#endif

46
ifchd/log.c Normal file
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@@ -0,0 +1,46 @@
/* log.c - simple logging support for ncron
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include <stdio.h>
#include <strings.h>
#include <syslog.h>
#include <stdarg.h>
#include "defines.h"
/* global logging flags */
int gflags_quiet = 0;
int gflags_detach = 1;
void log_line(char *format, ...) {
va_list argp;
if (format == NULL || gflags_quiet)
return;
if (gflags_detach) {
openlog("ifchd", LOG_PID, LOG_DAEMON);
va_start(argp, format);
vsyslog(LOG_ERR | LOG_DAEMON, format, argp);
va_end(argp);
closelog();
} else {
va_start(argp, format);
vfprintf(stderr, format, argp);
va_end(argp);
}
closelog();
}

26
ifchd/log.h Normal file
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@@ -0,0 +1,26 @@
/* log.h - simple logging support for ncron
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef NJK_LOG_H_
#define NJK_LOG_H_ 1
extern int gflags_quiet;
extern int gflags_detach;
void log_line(char* format, ...);
#endif

46
ifchd/nstrl.c Normal file
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@@ -0,0 +1,46 @@
/* nstrl.c - strlcpy/strlcat implementation
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include <unistd.h>
#ifndef HAVE_STRLCPY
size_t strlcpy (char *dest, char *src, size_t size)
{
register char *d = dest, *s = src;
for (; *s != '\0' && size > 0; size--, d++, s++)
*d = *s;
*d = '\0';
return (d - dest) + (s - src);
}
size_t strlcat (char *dest, char *src, size_t size)
{
register char *d = dest, *s = src;
for (; size > 0 && *d != '\0'; size--, d++);
for (; *s != '\0' && size > 0; size--, d++, s++)
*d = *s;
*d = '\0';
return (d - dest) + (s - src);
}
#endif

23
ifchd/nstrl.h Normal file
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@@ -0,0 +1,23 @@
/* nstrl.h - header file for strlcpy/strlcat implementation
(C) 2003 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifndef NJK_HAVE_STRL_
#define NJK_HAVE_STRL_ 1
size_t strlcpy (char *dest, char *src, size_t size);
size_t strlcat (char *dest, char *src, size_t size);
#endif

45
ifchd/pidfile.c Normal file
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@@ -0,0 +1,45 @@
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include "defines.h"
#include "log.h"
void write_pid(char *file) {
FILE *f;
char buf[MAXLINE];
if (!file)
return;
f = fopen(file, "w");
if (f == NULL) {
log_line("FATAL - failed to open pid file \"%s\"!\n", file);
exit(EXIT_FAILURE);
}
snprintf(buf, sizeof buf, "%i", (unsigned int)getpid());
fwrite(buf, sizeof (char), strlen(buf), f);
if (fclose(f) != 0) {
log_line("FATAL - failed to close pid file \"%s\"!\n", file);
exit(EXIT_FAILURE);
}
}
/* Return 0 on success, -1 on failure. */
int file_exists(char *file, char *mode) {
FILE *f;
if (file == NULL || mode == NULL)
return -1;
f = fopen(file, mode);
if (f == NULL)
return -1;
fclose(f);
return 0;
}

6
ifchd/pidfile.h Normal file
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@@ -0,0 +1,6 @@
#ifndef NJK_PIDFILE_H_
#define NJK_PIDFILE_H_ 1
void write_pid(char *file);
int file_exists(char *file, char *mode);
#endif

46
ifchd/signals.c Normal file
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@@ -0,0 +1,46 @@
/* signals.c - abstracts signal handling
(C) 2004 Nicholas J. Kain <njk@aerifal.cx>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include "log.h"
void hook_signal(int signum, void (*fn)(int), int flags) {
struct sigaction new_action;
new_action.sa_handler = fn;
sigemptyset(&new_action.sa_mask);
new_action.sa_flags = flags;
if (sigaction(signum, &new_action, NULL)) {
log_line("FATAL - failed to hook signal %i\n", signum);
exit(EXIT_FAILURE);
}
}
void disable_signal(int signum) {
struct sigaction new_action;
new_action.sa_handler = SIG_IGN;
sigemptyset(&new_action.sa_mask);
if (sigaction(signum, &new_action, NULL)) {
log_line("FATAL - failed to ignore signal %i\n", signum);
exit(EXIT_FAILURE);
}
}

6
ifchd/signals.h Normal file
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@@ -0,0 +1,6 @@
#ifndef NJK_SIGNALS_H_
#define NJK_SIGNALS_H_ 1
void hook_signal(int signum, void (*fn)(int), int flags);
void disable_signal(int signum);
#endif

71
ifchd/strlist.c Normal file
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@@ -0,0 +1,71 @@
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include "nstrl.h"
#include "strlist.h"
void add_to_strlist(char *name, strlist_t **list)
{
strlist_t *item, *t;
char *s;
unsigned int len;
if (!list || !name)
return;
len = strlen(name);
if (!len)
return;
s = malloc(len + 1);
if (!s)
return;
strlcpy(s, name, len + 1);
item = malloc(sizeof (strlist_t));
if (!item)
goto out0;
item->str = s;
item->next = NULL;
if (!*list) {
*list = item;
return;
}
for (t = *list; t->next; t = t->next)
if (!t->next) {
t->next = item;
return;
}
free(item); /* should be impossible, but hey */
out0:
free(s);
return;
}
void free_strlist(strlist_t *head)
{
strlist_t *p = head, *q = NULL;
while (p != NULL) {
free(p->str);
q = p;
p = q->next;
free(q);
}
}
void free_stritem(strlist_t **p)
{
strlist_t *q;
if (!p || !*p)
return;
q = (*p)->next;
free((*p)->str);
free(*p);
*p = q;
}

14
ifchd/strlist.h Normal file
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@@ -0,0 +1,14 @@
#ifndef NJK_STRLIST_H_
#define NJK_STRLIST_H_ 1
typedef struct
{
char *str;
void *next;
} strlist_t;
void add_to_strlist(char *name, strlist_t **list);
void free_strlist(strlist_t *head);
void free_stritem(strlist_t **p);
#endif