X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=ipif%2Fservice.c;h=08b0ed9f61a40859d37f531231940433db77d76c;hb=5f3e811b5415dcff74f82bdd2f26d3af1f73c555;hp=b7706235d6227e6943b0cf4d596aabff1423e16f;hpb=1e9634732a90ffe9bf3aeff4be92b5baa402599f;p=userv-utils.git diff --git a/ipif/service.c b/ipif/service.c index b770623..08b0ed9 100644 --- a/ipif/service.c +++ b/ipif/service.c @@ -1,35 +1,114 @@ /* - * userv service (or standalone program) - * for per-user IP subranges. + * userv service (or standalone program) for per-user IP subranges. + * + * When invoked appropriately, it creates a point-to-point network + * interface with specified parameters. It arranges for packets sent out + * via that interface by the kernel to appear on its own stdout in SLIP or + * CSLIP encoding, and packets injected into its own stdin to be given to + * the kernel as if received on that interface. Optionally, additional + * routes can be set up to arrange for traffic for other address ranges to + * be routed through the new interface. + * + * This is the service program, which is invoked as root from userv (or may + * be invoked firectly). + * + * Its arguments are supposed to be, in order, as follows: + * + * The first two arguments are usually supplied by the userv + * configuration. See the file `ipif/ipif' in the source tree, which + * is installed in /etc/userv/services.d/ipif by `make install': * - * This is invoked as root, directly from userv. - * Its arguments are supposed to be, in order: * - * Specifies address ranges and gids which own them. - * -- Indicates that the remaining arguments are user-supplied - * and therefore untrusted. + * + * Specifies address ranges and gids which own them. The default + * configuration supplies /etc/userv/ipif-networks, which is then read + * for a list of entries, one per line. + * + * -- + * Serves to separate the user-supplied and therefore untrusted + * arguments from the trusted first argument. + * + * The remaining arguments are supplied by the (untrusted) caller: + * * ,,, + * * As for slattach. Supported protocols are slip, cslip, and - * adaptive. Alternatively, set to `debug' to print debugging - * info. is address of the interface on chiark; - * is the address of the point-to-point peer. + * adaptive. Alternatively, set to `debug' to print debugging info + * and exit. is address of the interface to be created + * on the local system; is the address of the + * point-to-point peer. They must be actual addresses (not + * hostnames). + * * /,/,... - * List of additional routes to add for this interface. - * May be the empty argument. * - * is either - * ,/[,] - * indicating that that gid may allocate addresses in - * the relevant subspace ( is ignored) - * or #... - * which is a comment - * or / or ./ or ../ - * which refers to a file which contains lines which - * are each - * or * - * which means that anything is permitted - * - * Should be run from userv with no-disconnect-hup. + * List of additional routes to add for this interface. routes will + * be set up on the local system arranging for packets for those + * networks to be sent via the created interface. must be an + * IPv4 address, and mask must be an integer (dotted-quad masks are + * not supported). If no additional routes are to be set up, use `-' + * or supply an empty argument. + * + * Each item - whether a line file such as + * /etc/userv/ipif-networks, or supplied on the service program + * command line - is one of: + * + * / + * ./ + * ../ + * + * Reads a file which contains lines which are each + * items. + * + * ,[=][-|+]/(-|+/...)[,] + * + * Indicates that may allocate addresses in the relevant address + * range ( is ignored). must be numeric. To specify a + * single host address, you must specify a mask of /32. If `=' is + * specified then the specific subrange is only allowed for the local + * endpoint address, but not for remote addresses. + * + * More than one range may be given, with each range prefixed + * by + or -. In this case each address range in the rule will + * scanned in order, and the first range in the rule that matches + * any desired rule will count: if that first matching range is + * prefixed by `+' (or nothing) then the rule applies, if it + * is prefixed by `-' (or nothing matches), the rule does not. + * + * * + * Means that anything is to be permitted. This should not appear in + * /etc/userv/ipif-networks, as that would permit any user on the + * system to create any interfaces with any addresses and routes + * attached. It is provided so that root can usefully invoke the ipif + * service program directly (not via userv), without needing to set up + * permissions in /etc/userv/ipif-networks. + * + * #... + * + * Comment. Blank lines are also ignored. + * + * NB: Permission is granted if _any_ config entry matches the request. + * + * The service program should be run from userv with no-disconnect-hup. + */ +/* + * Copyright (C) 1999-2000,2003 Ian Jackson + * This file is part of ipif, part of userv-utils + * + * This 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 userv-utils; if not, write to the Free Software + * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * $Id$ */ #include @@ -40,21 +119,29 @@ #include #include #include +#include +#include + +#include +#include +#include #define NARGS 4 -#define MAXEXROUTES 5 -#define ATXTLEN 12 +#define MAXEXROUTES 50 +#define ATXTLEN 16 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2); static const char *const protos_ok[]= { "slip", "cslip", "adaptive", 0 }; +static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 }; static const char *configstr, *proto; static unsigned long localaddr, peeraddr, mtu; +static int localpming, peerpming; static int localallow, peerallow, allallow; static int nexroutes; static struct exroute { unsigned long prefix, mask; - int allow; + int allow, pming; char prefixtxt[ATXTLEN], masktxt[ATXTLEN]; } exroutes[MAXEXROUTES]; @@ -67,6 +154,58 @@ static struct pplace { int lineno; } *cpplace; + +static int slpipe[2], ptmaster, undoslattach; +static const char *ifname; +static const char *ptyname; + +#define NPIDS 4 + +static union { + struct { pid_t sl, cout, cin, task; } byname; + pid_t bynumber[NPIDS]; +} pids; +sigset_t emptyset, fullset; + + +static int cleantask(void) { + pid_t pid; + + pid= fork(); + if (!pid) return 1; + if (pid == (pid_t)-1) + perror("userv-ipif: fork for undo slattach failed - cannot clean up properly"); + return 0; +} + +static void terminate(int estatus) { + int i, status; + pid_t pid; + + for (i=0; ifilename, cpp->lineno); } } - exit(16); + terminate(16); } static char *ip2txt(unsigned long addr, char *buf) { @@ -143,13 +282,13 @@ static unsigned long eat_number(const char **argp, const char *what, char *ep; int endchar; - if (!*argp) { badusage("missing number %s\n",what); } + if (!*argp) { badusage("missing number %s",what); } rv= strtoul(*argp,&ep,0); if ((endchar= *ep)) { - if (!endchars) badusage("junk after number %s\n",what); + if (!endchars) badusage("junk after number %s",what); if (!strchr(endchars,endchar)) badusage("invalid character or delimiter `%c' in or after number, %s:" - " expected %s (or none?)\n", endchar,what,endchars); + " expected %s (or none?)", endchar,what,endchars); *argp= ep+1; } else { *argp= 0; @@ -160,12 +299,17 @@ static unsigned long eat_number(const char **argp, const char *what, return rv; } -static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1, - const char *w2, unsigned long p2, unsigned long m2) { +static int addrnet_overlap(unsigned long p1, unsigned long m1, + unsigned long p2, unsigned long m2) { unsigned long mask; mask= m1&m2; - if ((p1 & mask) != (p2 & mask)) return; + return (p1 & mask) == (p2 & mask); +} + +static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1, + const char *w2, unsigned long p2, unsigned long m2) { + if (!addrnet_overlap(p1,m1,p2,m2)) return; badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx", w1,p1,m1, w2,p2,m2); } @@ -199,8 +343,8 @@ static void eat_prefixmask(const char **argp, const char *what, sprintf(whatbuf,"%s length",what); len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r); - mask= (~0UL << (32-len)); - if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx\n", + mask= len ? (~0UL << (32-len)) : 0UL; + if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx", what,prefix,mask); *prefix_r= prefix; if (mask_r) *mask_r= mask; @@ -211,32 +355,66 @@ static int addrnet_isin(unsigned long prefix, unsigned long mask, unsigned long mprefix, unsigned long mmask) { return !(~mask & mmask) && (prefix & mmask) == mprefix; } + +/* Totally hideous algorithm for parsing the config file lines. + * For each config file line, we first see if its gid applies. If not + * we skip it. Otherwise, we do + * permit_begin + * which sets pming to 1 + * for each range. pming may be 0 if we've determined that + * this line does not apply to . + * permit_range + * which calls permit_range_thing for each + * which checks to see if is inside the relevant + * range (for +) or overlaps it (for -) and updates + * allow and pming. + */ + +static void permit_begin(void) { + int i; + localpming= peerpming= 1; + for (i=0; isa_handler= handler; + sa->sa_flags= 0; + for (signalp=signals; (sig=*signalp); signalp++) { + r= sigaction(sig, sa, 0); if (r) sysfatal("uncatch signal"); + } + sa->sa_flags= chldflags; + r= sigaction(SIGCHLD, sa, 0); if (r) sysfatal("uncatch children"); +} + +static void infork(void) { + struct sigaction sa; + + memset(&pids,0,sizeof(pids)); + sigemptyset(&sa.sa_mask); + setsignals(SIG_DFL,&sa,0); + setsigmask(&emptyset); + undoslattach= 0; +} + +static pid_t makesubproc(void (*entry)(void)) { + pid_t pid; + + pid= fork(); if (pid == (pid_t)-1) sysfatal("fork for subprocess"); + if (pid) return pid; + + infork(); + entry(); + abort(); +} + +static int task(void) { + pid_t pid; + + pid= fork(); + if (pid == (pid_t)-1) sysfatal("fork for task"); + if (!pid) { infork(); return 1; } + + pids.byname.task= pid; + while (pids.byname.task) sigsuspend(&emptyset); + return 0; +} + +static void mdup2(int fd1, int fd2, const char *what) { + int r; + + for (;;) { + r= dup2(fd1,fd2); if (r==fd2) return; + if (r!=-1) fatal("dup2 in %s gave wrong answer %d instead of %d",what,r,fd2); + if (errno != EINTR) sysfatal("dup2 failed in %s",what); + } +} + +static void sl_entry(void) { + mdup2(slpipe[1],1,"slattach child"); + execlp("slattach", "slattach", "-v", "-L", "-p",proto, ptyname, (char*)0); + sysfatal("cannot exec slattach"); +} + +static void cin_entry(void) { + mdup2(ptmaster,1,"cat input child"); + execlp("cat", "cat", (char*)0); + sysfatal("cannot exec cat input"); +} + +static void cout_entry(void) { + mdup2(ptmaster,0,"cat output child"); + execlp("cat", "cat", (char*)0); + sysfatal("cannot exec cat output"); +} + +static void sighandler(int signum) { + pid_t pid; + int estatus, status; + const char *taskfail; + + estatus= 4; + + if (signum == SIGCHLD) { + for (;;) { + pid= waitpid(-1,&status,WNOHANG); + if (!pid || pid == (pid_t)-1) return; + + if (pid == pids.byname.task) { + pids.byname.task= 0; + if (!status) return; + taskfail= "task"; + } else if (pid == pids.byname.cin) { + pids.byname.cin= 0; + if (status) { + taskfail= "input cat"; + } else { + taskfail= 0; + estatus= 0; + } + } else if (pid == pids.byname.cout) { + pids.byname.cout= 0; + taskfail= "output cat"; + } else if (pid == pids.byname.sl) { + pids.byname.sl= 0; + taskfail= "slattach"; + } else { + continue; + } + break; + } + if (taskfail) { + if (WIFEXITED(status)) { + fprintf(stderr, + "userv-ipif service: %s unexpectedly exited with exit status %d\n", + taskfail, WEXITSTATUS(status)); + } else if (WIFSIGNALED(status)) { + fprintf(stderr, + "userv-ipif service: %s unexpectedly killed by signal %s%s\n", + taskfail, strsignal(WTERMSIG(status)), + WCOREDUMP(status) ? " (core dumped)" : ""); + } else { + fprintf(stderr, "userv-ipif service: %s unexpectedly terminated" + " with unknown status code %d\n", taskfail, status); + } + } + } else { + fprintf(stderr, + "userv-ipif service: received signal %d, terminating\n", + signum); + } + + terminate(estatus); +} + +static void startup(void) { + int r; + struct sigaction sa; + + sigfillset(&fullset); + sigemptyset(&emptyset); + + ptmaster= getpt(); if (ptmaster==-1) sysfatal("allocate pty master"); + r= grantpt(ptmaster); if (r) sysfatal("grab/grant pty slave"); + ptyname= ptsname(ptmaster); if (!ptyname) sysfatal("get pty slave name"); + r= chmod(ptyname,0600); if (r) sysfatal("chmod pty slave"); + r= unlockpt(ptmaster); if (r) sysfatal("unlock pty"); + + sigfillset(&sa.sa_mask); + setsignals(sighandler,&sa,SA_NOCLDSTOP); + setsigmask(&fullset); +} + +static void startslattach(void) { + static char ifnbuf[200]; + + FILE *piper; + int r, l, k; + + r= pipe(slpipe); if (r) sysfatal("create pipe"); + piper= fdopen(slpipe[0],"r"); if (!piper) sysfatal("fdopen pipe"); + + undoslattach= 1; + pids.byname.sl= makesubproc(sl_entry); + + close(slpipe[1]); + setsigmask(&emptyset); + if (!fgets(ifnbuf,sizeof(ifnbuf),piper)) { + if (ferror(piper)) sysfatal("cannot read ifname from slattach"); + else fatal("cannot read ifname from slattach"); + } + setsigmask(&fullset); + l= strlen(ifnbuf); + if (l<=0 || ifnbuf[l-1] != '\n') fatal("slattach gave strange output `%s'",ifnbuf); + ifnbuf[l-1]= 0; + for (k=l; k>0 && ifnbuf[k-1]!=' '; k--); + ifname= ifnbuf+k; +} + +static void netconfigure(void) { + char mtutxt[100]; + int i; + + if (task()) { + sprintf(mtutxt,"%lu",mtu); + + execlp("ifconfig", "ifconfig", ifname, localtxt, + "netmask","255.255.255.255", "-broadcast", "pointopoint",peertxt, + "mtu",mtutxt, "up", (char*)0); + sysfatal("cannot exec ifconfig"); + } + + for (i=0; i