2 * userv service (or standalone program) for per-user IP subranges.
4 * When invoked appropriately, it creates a point-to-point network
5 * interface with specified parameters. It arranges for packets sent out
6 * via that interface by the kernel to appear on its own stdout in SLIP or
7 * CSLIP encoding, and packets injected into its own stdin to be given to
8 * the kernel as if received on that interface. Optionally, additional
9 * routes can be set up to arrange for traffic for other address ranges to
10 * be routed through the new interface.
12 * This is the service program, which is invoked as root from userv (or may
13 * be invoked firectly).
15 * Its arguments are supposed to be, in order, as follows:
17 * The first two arguments are usually supplied by the userv
18 * configuration. See the file `ipif/ipif' in the source tree, which
19 * is installed in /etc/userv/services.d/ipif by `make install':
23 * Specifies address ranges and gids which own them. The default
24 * configuration supplies /etc/userv/ipif-networks, which is then read
25 * for a list of entries, one per line.
28 * Serves to separate the user-supplied and therefore untrusted
29 * arguments from the trusted first argument.
31 * The remaining arguments are supplied by the (untrusted) caller:
33 * <local-addr>,<peer-addr>,<mtu>,<proto>
35 * As for slattach. Supported protocols are slip, cslip, and
36 * adaptive. Alternatively, set to `debug' to print debugging info
37 * and exit. <local-addr> is address of the interface to be created
38 * on the local system; <peer-addr> is the address of the
39 * point-to-point peer. They must be actual addresses (not
42 * <prefix>/<mask>,<prefix>/<mask>,...
44 * List of additional routes to add for this interface. routes will
45 * be set up on the local system arranging for packets for those
46 * networks to be sent via the created interface. <prefix> must be an
47 * IPv4 address, and mask must be an integer (dotted-quad masks are
48 * not supported). If no additional routes are to be set up, use `-'
49 * or supply an empty argument.
51 * Each <config> item - whether a line file such as
52 * /etc/userv/ipif-networks, or supplied on the service program
53 * command line - is one of:
56 * ./<config-file-name>
57 * ../<config-file-name>
59 * Reads a file which contains lines which are each <config>
62 * <gid>,[=]<prefix>/<len>[,<junk>]
64 * Indicates that <gid> may allocate addresses in the relevant address
65 * range (<junk> is ignored). <gid> must be numeric. To specify a
66 * single host address, you must specify a mask of /32. If `=' is
67 * specified then the specific subrange is only allowed for the local
68 * endpoint address, but not for remote addresses.
71 * Means that anything is to be permitted. This should not appear in
72 * /etc/userv/ipif-networks, as that would permit any user on the
73 * system to create any interfaces with any addresses and routes
74 * attached. It is provided so that root can usefully invoke the ipif
75 * service program directly (not via userv), without needing to set up
76 * permissions in /etc/userv/ipif-networks.
80 * Comment. Blank lines are also ignored.
82 * NB: Permission is granted if _any_ config entry matches the request.
84 * The service program should be run from userv with no-disconnect-hup.
87 * Copyright (C) 1999-2000 Ian Jackson
89 * This is free software; you can redistribute it and/or modify it
90 * under the terms of the GNU General Public License as published by
91 * the Free Software Foundation; either version 2 of the License, or
92 * (at your option) any later version.
94 * This program is distributed in the hope that it will be useful, but
95 * WITHOUT ANY WARRANTY; without even the implied warranty of
96 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
97 * General Public License for more details.
99 * You should have received a copy of the GNU General Public License
100 * along with userv-utils; if not, write to the Free Software
101 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
117 #include <sys/types.h>
118 #include <sys/wait.h>
119 #include <sys/stat.h>
122 #define MAXEXROUTES 5
125 static const unsigned long gidmaxval
= (unsigned long)((gid_t
)-2);
126 static const char *const protos_ok
[]= { "slip", "cslip", "adaptive", 0 };
127 static const int signals
[]= { SIGHUP
, SIGINT
, SIGTERM
, 0 };
129 static const char *configstr
, *proto
;
130 static unsigned long localaddr
, peeraddr
, mtu
;
131 static int localallow
, peerallow
, allallow
;
132 static int nexroutes
;
133 static struct exroute
{
134 unsigned long prefix
, mask
;
136 char prefixtxt
[ATXTLEN
], masktxt
[ATXTLEN
];
137 } exroutes
[MAXEXROUTES
];
139 static char localtxt
[ATXTLEN
];
140 static char peertxt
[ATXTLEN
];
142 static struct pplace
{
143 struct pplace
*parent
;
144 const char *filename
;
149 static int slpipe
[2], ptmaster
, undoslattach
;
150 static const char *ifname
;
151 static const char *ptyname
;
156 struct { pid_t sl
, cout
, cin
, task
; } byname
;
157 pid_t bynumber
[NPIDS
];
159 sigset_t emptyset
, fullset
;
162 static int cleantask(void) {
167 if (pid
== (pid_t
)-1)
168 perror("userv-ipif: fork for undo slattach failed - cannot clean up properly");
172 static void terminate(int estatus
) {
176 for (i
=0; i
<NPIDS
; i
++)
177 if (pids
.bynumber
[i
]) kill(pids
.bynumber
[i
], SIGTERM
);
181 execlp("slattach", "slattach", "-p", "tty", ptyname
, (char*)0);
182 perror("userv-ipif: exec slattach for undo slattach failed");
185 if (ifname
&& cleantask()) {
186 execlp("ifconfig", "ifconfig", ifname
, "down", (char*)0);
187 perror("userv-ipif: exec ifconfig for undo ifconfig failed");
193 pid
= waitpid(-1,&status
,0);
194 if (pid
== (pid_t
)-1) break;
200 static void fatal(const char *fmt
, ...)
201 __attribute__((format(printf
,1,2)));
202 static void fatal(const char *fmt
, ...) {
206 fputs("userv-ipif service: fatal error: ",stderr
);
207 vfprintf(stderr
, fmt
, al
);
212 static void sysfatal(const char *fmt
, ...)
213 __attribute__((format(printf
,1,2)));
214 static void sysfatal(const char *fmt
, ...) {
221 fputs("userv-ipif service: fatal system error: ",stderr
);
222 vfprintf(stderr
, fmt
, al
);
223 fprintf(stderr
,": %s\n", strerror(e
));
228 static void badusage(const char *fmt
, ...)
229 __attribute__((format(printf
,1,2)));
230 static void badusage(const char *fmt
, ...) {
236 "userv-ipif service: %s:%d: ",
237 cpplace
->filename
, cpplace
->lineno
);
239 fputs("userv-ipif service: invalid usage: ",stderr
);
242 vfprintf(stderr
, fmt
, al
);
246 for (cpp
=cpplace
->parent
; cpp
; cpp
=cpp
->parent
) {
248 "userv-ipif service: %s:%d: ... in file included from here\n",
249 cpp
->filename
, cpp
->lineno
);
255 static char *ip2txt(unsigned long addr
, char *buf
) {
256 sprintf(buf
, "%lu.%lu.%lu.%lu",
264 static unsigned long eat_number(const char **argp
, const char *what
,
265 unsigned long min
, unsigned long max
,
266 const char *endchars
, int *endchar_r
) {
267 /* If !endchars then the endchar must be a nul, otherwise it may be
268 * a nul (resulting in *argp set to 0) or something else (*argp set
269 * to point to after delim, *endchar_r set to delim).
270 * *endchar_r may be 0.
276 if (!*argp
) { badusage("missing number %s",what
); }
277 rv
= strtoul(*argp
,&ep
,0);
278 if ((endchar
= *ep
)) {
279 if (!endchars
) badusage("junk after number %s",what
);
280 if (!strchr(endchars
,endchar
))
281 badusage("invalid character or delimiter `%c' in or after number, %s:"
282 " expected %s (or none?)", endchar
,what
,endchars
);
287 if (endchar_r
) *endchar_r
= endchar
;
288 if (rv
< min
|| rv
> max
) badusage("number %s value %lu out of range %lu..%lu",
293 static void addrnet_mustdiffer(const char *w1
, unsigned long p1
, unsigned long m1
,
294 const char *w2
, unsigned long p2
, unsigned long m2
) {
298 if ((p1
& mask
) != (p2
& mask
)) return;
299 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
303 static unsigned long eat_addr(const char **argp
, const char *what
,
304 const char *endchars
, int *endchar_r
) {
313 sprintf(whatbuf
,"%s byte #%d",what
,i
);
314 rv
|= eat_number(argp
,whatbuf
, 0,255, i
<3 ?
"." : endchars
, endchar_r
);
320 static void eat_prefixmask(const char **argp
, const char *what
,
321 const char *endchars
, int *endchar_r
,
322 unsigned long *prefix_r
, unsigned long *mask_r
, int *len_r
) {
323 /* mask_r and len_r may be 0 */
326 unsigned long prefix
, mask
;
328 prefix
= eat_addr(argp
,what
, "/",0);
329 sprintf(whatbuf
,"%s length",what
);
330 len
= eat_number(argp
,whatbuf
, 0,32, endchars
,endchar_r
);
332 mask
= (~0UL << (32-len
));
333 if (prefix
& ~mask
) badusage("%s prefix %08lx not fully contained in mask %08lx",
336 if (mask_r
) *mask_r
= mask
;
337 if (len_r
) *len_r
= len
;
340 static int addrnet_isin(unsigned long prefix
, unsigned long mask
,
341 unsigned long mprefix
, unsigned long mmask
) {
342 return !(~mask
& mmask
) && (prefix
& mmask
) == mprefix
;
346 static void permit(unsigned long pprefix
, unsigned long pmask
, int localonly
) {
349 assert(!(pprefix
& ~pmask
));
352 if (!proto
) fputs(localonly ?
"permits-l" : "permits",stdout
);
353 if (addrnet_isin(localaddr
,~0UL, pprefix
,pmask
)) {
354 if (!proto
) fputs(" local-addr",stdout
);
358 if (addrnet_isin(peeraddr
,~0UL, pprefix
,pmask
)) {
359 if (!proto
) fputs(" peer-addr",stdout
);
362 for (i
=0; i
<nexroutes
; i
++) {
363 if (addrnet_isin(exroutes
[i
].prefix
,exroutes
[i
].mask
, pprefix
,pmask
)) {
364 if (!proto
) printf(" route#%d",i
);
365 any
= exroutes
[i
].allow
= 1;
370 if (!any
) fputs(" nothing",stdout
);
375 static void pconfig(const char *configstr
, int truncated
);
377 static void pfile(const char *filename
) {
381 struct pplace npp
, *cpp
;
383 for (cpp
=cpplace
; cpp
; cpp
=cpp
->parent
) {
384 if (!strcmp(cpp
->filename
,filename
))
385 badusage("recursive configuration file `%s'",filename
);
388 file
= fopen(filename
,"r");
390 badusage("cannot open configuration file `%s': %s", filename
, strerror(errno
));
392 if (!proto
) printf("config file `%s':\n",filename
);
395 npp
.filename
= filename
;
399 while (fgets(buf
, sizeof(buf
), file
)) {
404 truncated
= (buf
[l
-1] != '\n');
405 while (l
>0 && isspace((unsigned char) buf
[l
-1])) l
--;
410 while ((c
= getc(file
)) != EOF
&& c
!= '\n');
414 pconfig(buf
,truncated
);
417 badusage("failed while reading configuration file: %s", strerror(errno
));
422 static void pconfig(const char *configstr
, int truncated
) {
423 unsigned long fgid
, tgid
, pprefix
, pmask
;
428 switch (configstr
[0]) {
430 if (strcmp(configstr
,"*")) badusage("`*' directive must be only thing on line");
438 if (truncated
) badusage("filename too long (`%.100s...')",configstr
);
443 if (!isdigit((unsigned char)configstr
[0]))
444 badusage("unknown configuration directive");
446 fgid
= eat_number(&configstr
,"gid", 0,gidmaxval
, ",",0);
447 if (configstr
[0] == '=') {
453 eat_prefixmask(&configstr
,"permitted-prefix", ",",0, &pprefix
,&pmask
,&plen
);
454 if (!configstr
&& truncated
) badusage("gid,prefix/len,... spec too long");
456 if (!proto
) printf(" %5lu,%s/%d: ", fgid
, ip2txt(pprefix
,ptxt
), plen
);
458 gidlist
= getenv("USERV_GID");
459 if (!gidlist
) fatal("USERV_GID not set");
462 if (!proto
) printf("no matching gid\n");
465 tgid
= eat_number(&gidlist
,"userv-gid", 0,gidmaxval
, " ",0);
466 if (tgid
== fgid
) break;
468 permit(pprefix
,pmask
,localonly
);
473 static void checkallow(int allow
, const char *what
,
474 const char *prefixtxt
, const char *masktxt
) {
476 fprintf(stderr
,"userv-ipif service: access denied for %s, %s/%s\n",
477 what
, prefixtxt
, masktxt
);
481 static void parseargs(int argc
, const char *const *argv
) {
482 unsigned long routeaddr
, routemask
;
484 const char *const *cprotop
;
486 char erwhatbuf
[100], erwhatbuf2
[100];
488 if (argc
< NARGS
+1) { badusage("too few arguments"); }
489 if (argc
> NARGS
+1) { badusage("too many arguments"); }
494 if (strcmp(carg
,"--")) badusage("separator argument `--' not found, got `%s'",carg
);
497 localaddr
= eat_addr(&carg
,"local-addr", ",",0);
498 peeraddr
= eat_addr(&carg
,"peer-addr", ",",0);
499 mtu
= eat_number(&carg
,"mtu", 576,65536, ",",0);
500 localallow
= peerallow
= 0;
502 if (!strcmp(carg
,"debug")) {
505 for (cprotop
= protos_ok
;
506 (proto
= *cprotop
) && strcmp(proto
,carg
);
508 if (!proto
) fatal("invalid protocol");
511 addrnet_mustdiffer("local-addr",localaddr
,~0UL, "peer-addr",peeraddr
,~0UL);
514 if (strcmp(carg
,"-")) {
518 if (nexroutes
== MAXEXROUTES
)
519 fatal("too many extra routes (only %d allowed)",MAXEXROUTES
);
520 sprintf(erwhatbuf
,"route#%d",nexroutes
);
522 eat_prefixmask(&carg
,erwhatbuf
, ",",0, &routeaddr
,&routemask
,0);
523 if (routemask
== ~0UL) {
524 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
, "local-addr",localaddr
,~0UL);
525 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
, "peer-addr",peeraddr
,~0UL);
527 for (i
=0; i
<nexroutes
; i
++) {
528 sprintf(erwhatbuf2
,"route#%d",i
);
529 addrnet_mustdiffer(erwhatbuf
,routeaddr
,routemask
,
530 erwhatbuf2
,exroutes
[i
].prefix
,exroutes
[i
].mask
);
532 exroutes
[nexroutes
].prefix
= routeaddr
;
533 exroutes
[nexroutes
].mask
= routemask
;
534 exroutes
[nexroutes
].allow
= 0;
535 ip2txt(routeaddr
,exroutes
[nexroutes
].prefixtxt
);
536 ip2txt(routemask
,exroutes
[nexroutes
].masktxt
);
540 ip2txt(localaddr
,localtxt
);
541 ip2txt(peeraddr
,peertxt
);
544 static void checkpermit(void) {
549 checkallow(localallow
,"local-addr", localtxt
,"32");
550 checkallow(peerallow
,"peer-addr", peertxt
,"32");
551 for (i
=0; i
<nexroutes
; i
++) {
552 sprintf(erwhatbuf
, "route#%d", i
);
553 checkallow(exroutes
[i
].allow
, erwhatbuf
, exroutes
[i
].prefixtxt
, exroutes
[i
].masktxt
);
555 if (!allallow
) fatal("access denied");
558 static void dumpdebug(void) __attribute__((noreturn
));
559 static void dumpdebug(void) {
563 printf("protocol: debug\n"
564 "local: %08lx == %s\n"
565 "peer: %08lx == %s\n"
572 for (i
=0; i
<nexroutes
; i
++) {
573 sprintf(erwhatbuf
, "route#%d:", i
);
574 printf("%-9s %08lx/%08lx == %s/%s\n",
576 exroutes
[i
].prefix
, exroutes
[i
].mask
,
577 exroutes
[i
].prefixtxt
, exroutes
[i
].masktxt
);
579 if (ferror(stdout
) || fclose(stdout
)) sysfatal("flush stdout");
584 static void setsigmask(const sigset_t
*ss
) {
587 r
= sigprocmask(SIG_SETMASK
, ss
, 0);
588 if (r
) sysfatal("[un]block signals");
591 static void setsignals(void (*handler
)(int), struct sigaction
*sa
, int chldflags
) {
595 sa
->sa_handler
= handler
;
597 for (signalp
=signals
; (sig
=*signalp
); signalp
++) {
598 r
= sigaction(sig
, sa
, 0); if (r
) sysfatal("uncatch signal");
600 sa
->sa_flags
= chldflags
;
601 r
= sigaction(SIGCHLD
, sa
, 0); if (r
) sysfatal("uncatch children");
604 static void infork(void) {
607 memset(&pids
,0,sizeof(pids
));
608 sigemptyset(&sa
.sa_mask
);
609 setsignals(SIG_DFL
,&sa
,0);
610 setsigmask(&emptyset
);
614 static pid_t
makesubproc(void (*entry
)(void)) {
617 pid
= fork(); if (pid
== (pid_t
)-1) sysfatal("fork for subprocess");
625 static int task(void) {
629 if (pid
== (pid_t
)-1) sysfatal("fork for task");
630 if (!pid
) { infork(); return 1; }
632 pids
.byname
.task
= pid
;
633 while (pids
.byname
.task
) sigsuspend(&emptyset
);
637 static void mdup2(int fd1
, int fd2
, const char *what
) {
641 r
= dup2(fd1
,fd2
); if (r
==fd2
) return;
642 if (r
!=-1) fatal("dup2 in %s gave wrong answer %d instead of %d",what
,r
,fd2
);
643 if (errno
!= EINTR
) sysfatal("dup2 failed in %s",what
);
647 static void sl_entry(void) {
648 mdup2(slpipe
[1],1,"slattach child");
649 execlp("slattach", "slattach", "-v", "-L", "-p",proto
, ptyname
, (char*)0);
650 sysfatal("cannot exec slattach");
653 static void cin_entry(void) {
654 mdup2(ptmaster
,1,"cat input child");
655 execlp("cat", "cat", (char*)0);
656 sysfatal("cannot exec cat input");
659 static void cout_entry(void) {
660 mdup2(ptmaster
,0,"cat output child");
661 execlp("cat", "cat", (char*)0);
662 sysfatal("cannot exec cat output");
665 static void sighandler(int signum
) {
668 const char *taskfail
;
672 if (signum
== SIGCHLD
) {
674 pid
= waitpid(-1,&status
,WNOHANG
);
675 if (!pid
|| pid
== (pid_t
)-1) return;
677 if (pid
== pids
.byname
.task
) {
681 } else if (pid
== pids
.byname
.cin
) {
684 taskfail
= "input cat";
689 } else if (pid
== pids
.byname
.cout
) {
691 taskfail
= "output cat";
692 } else if (pid
== pids
.byname
.sl
) {
694 taskfail
= "slattach";
701 if (WIFEXITED(status
)) {
703 "userv-ipif service: %s unexpectedly exited with exit status %d\n",
704 taskfail
, WEXITSTATUS(status
));
705 } else if (WIFSIGNALED(status
)) {
707 "userv-ipif service: %s unexpectedly killed by signal %s%s\n",
708 taskfail
, strsignal(WTERMSIG(status
)),
709 WCOREDUMP(status
) ?
" (core dumped)" : "");
711 fprintf(stderr
, "userv-ipif service: %s unexpectedly terminated"
712 " with unknown status code %d\n", taskfail
, status
);
717 "userv-ipif service: received signal %d, terminating\n",
724 static void startup(void) {
728 sigfillset(&fullset
);
729 sigemptyset(&emptyset
);
731 ptmaster
= getpt(); if (ptmaster
==-1) sysfatal("allocate pty master");
732 r
= grantpt(ptmaster
); if (r
) sysfatal("grab/grant pty slave");
733 ptyname
= ptsname(ptmaster
); if (!ptyname
) sysfatal("get pty slave name");
734 r
= chmod(ptyname
,0600); if (r
) sysfatal("chmod pty slave");
735 r
= unlockpt(ptmaster
); if (r
) sysfatal("unlock pty");
737 sigfillset(&sa
.sa_mask
);
738 setsignals(sighandler
,&sa
,SA_NOCLDSTOP
);
739 setsigmask(&fullset
);
742 static void startslattach(void) {
743 static char ifnbuf
[200];
748 r
= pipe(slpipe
); if (r
) sysfatal("create pipe");
749 piper
= fdopen(slpipe
[0],"r"); if (!piper
) sysfatal("fdopen pipe");
752 pids
.byname
.sl
= makesubproc(sl_entry
);
755 setsigmask(&emptyset
);
756 if (!fgets(ifnbuf
,sizeof(ifnbuf
),piper
)) {
757 if (ferror(piper
)) sysfatal("cannot read ifname from slattach");
758 else fatal("cannot read ifname from slattach");
760 setsigmask(&fullset
);
762 if (l
<=0 || ifnbuf
[l
-1] != '\n') fatal("slattach gave strange output `%s'",ifnbuf
);
764 for (k
=l
; k
>0 && ifnbuf
[k
-1]!=' '; k
--);
768 static void netconfigure(void) {
773 sprintf(mtutxt
,"%lu",mtu
);
775 execlp("ifconfig", "ifconfig", ifname
, localtxt
,
776 "netmask","255.255.255.255", "-broadcast", "pointopoint",peertxt
,
777 "mtu",mtutxt
, "up", (char*)0);
778 sysfatal("cannot exec ifconfig");
781 for (i
=0; i
<nexroutes
; i
++) {
783 execlp("route","route", "add", "-net",exroutes
[i
].prefixtxt
,
784 "netmask",exroutes
[i
].masktxt
,
785 "gw",peertxt
, "dev",ifname
, (char*)0);
786 sysfatal("cannot exec route (for route)");
791 static void copydata(void) __attribute__((noreturn
));
792 static void copydata(void) {
795 pids
.byname
.cin
= makesubproc(cin_entry
);
797 r
= write(1, "\300", 1); if (r
==1) break;
798 assert(r
==-1); if (errno
!= EINTR
) sysfatal("send initial delim to confirm");
800 pids
.byname
.cout
= makesubproc(cout_entry
);
802 for (;;) sigsuspend(&emptyset
);
805 int main(int argc
, const char *const *argv
) {
806 parseargs(argc
,argv
);
807 pconfig(configstr
,0);
809 if (!proto
) dumpdebug();