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freebsd/usr.sbin/ppp/exec.c
Brian Somers 887ff31f06 When ``ppp -direct'' is invoked by a program that uses pipe(2) to 
create stdin and stdout, don't blindly try to use stdin as a bi-directional
channel.  Instead, detect the pipe and set up a special exec handler
that indirects write() calls through stdout.

This fixes the problem where ``set device "!ssh -e none host ppp
-direct label"'' no longer works with an openssh-5.2 server side as
that version of openssh ignores the USE_PIPES config setting and
*always* uses pipes (rather than socketpair) for stdin/stdout channels.

MFC after:	3 days
2009-08-24 17:19:45 +00:00

411 lines
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/*-
* Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <termios.h>
#include <unistd.h>
#include "layer.h"
#include "defs.h"
#include "mbuf.h"
#include "log.h"
#include "timer.h"
#include "lqr.h"
#include "hdlc.h"
#include "throughput.h"
#include "fsm.h"
#include "lcp.h"
#include "ccp.h"
#include "link.h"
#include "async.h"
#include "descriptor.h"
#include "physical.h"
#include "mp.h"
#include "chat.h"
#include "command.h"
#include "auth.h"
#include "chap.h"
#include "cbcp.h"
#include "datalink.h"
#include "id.h"
#include "main.h"
#include "exec.h"
struct execdevice {
struct device dev; /* What struct physical knows about */
int fd_out; /* output descriptor */
};
#define device2exec(d) ((d)->type == EXEC_DEVICE ? (struct execdevice *)d : NULL)
unsigned
exec_DeviceSize(void)
{
return sizeof(struct execdevice);
}
static void
exec_Free(struct physical *p)
{
struct execdevice *dev = device2exec(p->handler);
if (dev->fd_out != -1)
close(dev->fd_out);
free(dev);
}
static void
exec_device2iov(struct device *d, struct iovec *iov, int *niov,
int maxiov __unused, int *auxfd, int *nauxfd)
{
struct execdevice *dev;
int sz = physical_MaxDeviceSize();
iov[*niov].iov_base = d = realloc(d, sz);
if (d == NULL) {
log_Printf(LogALERT, "Failed to allocate memory: %d\n", sz);
AbortProgram(EX_OSERR);
}
iov[*niov].iov_len = sz;
(*niov)++;
dev = device2exec(d);
if (dev->fd_out >= 0) {
*auxfd = dev->fd_out;
(*nauxfd)++;
}
}
static int
exec_RemoveFromSet(struct physical *p, fd_set *r, fd_set *w, fd_set *e)
{
struct execdevice *dev = device2exec(p->handler);
int sets;
p->handler->removefromset = NULL;
sets = physical_RemoveFromSet(p, r, w, e);
p->handler->removefromset = exec_RemoveFromSet;
if (dev->fd_out >= 0) {
if (w && FD_ISSET(dev->fd_out, w)) {
FD_CLR(dev->fd_out, w);
log_Printf(LogTIMER, "%s: fdunset(w) %d\n", p->link.name, dev->fd_out);
sets++;
}
if (e && FD_ISSET(dev->fd_out, e)) {
FD_CLR(dev->fd_out, e);
log_Printf(LogTIMER, "%s: fdunset(e) %d\n", p->link.name, dev->fd_out);
sets++;
}
}
return sets;
}
static ssize_t
exec_Write(struct physical *p, const void *v, size_t n)
{
struct execdevice *dev = device2exec(p->handler);
int fd = dev->fd_out == -1 ? p->fd : dev->fd_out;
return write(fd, v, n);
}
static struct device baseexecdevice = {
EXEC_DEVICE,
"exec",
0,
{ CD_NOTREQUIRED, 0 },
NULL,
exec_RemoveFromSet,
NULL,
NULL,
NULL,
NULL,
NULL,
exec_Free,
NULL,
exec_Write,
exec_device2iov,
NULL,
NULL,
NULL
};
struct device *
exec_iov2device(int type, struct physical *p, struct iovec *iov,
int *niov, int maxiov __unused, int *auxfd, int *nauxfd)
{
if (type == EXEC_DEVICE) {
struct execdevice *dev = (struct execdevice *)iov[(*niov)++].iov_base;
dev = realloc(dev, sizeof *dev); /* Reduce to the correct size */
if (dev == NULL) {
log_Printf(LogALERT, "Failed to allocate memory: %d\n",
(int)(sizeof *dev));
AbortProgram(EX_OSERR);
}
if (*nauxfd) {
dev->fd_out = *auxfd;
(*nauxfd)--;
} else
dev->fd_out = -1;
/* Refresh function pointers etc */
memcpy(&dev->dev, &baseexecdevice, sizeof dev->dev);
physical_SetupStack(p, dev->dev.name, PHYSICAL_NOFORCE);
return &dev->dev;
}
return NULL;
}
static int
exec_UpdateSet(struct fdescriptor *d, fd_set *r, fd_set *w, fd_set *e, int *n)
{
struct physical *p = descriptor2physical(d);
struct execdevice *dev = device2exec(p->handler);
int result = 0;
if (w && dev->fd_out >= 0) {
FD_SET(dev->fd_out, w);
log_Printf(LogTIMER, "%s: fdset(w) %d\n", p->link.name, dev->fd_out);
result++;
w = NULL;
}
if (e && dev->fd_out >= 0) {
FD_SET(dev->fd_out, e);
log_Printf(LogTIMER, "%s: fdset(e) %d\n", p->link.name, dev->fd_out);
result++;
}
if (result && *n <= dev->fd_out)
*n = dev->fd_out + 1;
return result + physical_doUpdateSet(d, r, w, e, n, 0);
}
static int
exec_IsSet(struct fdescriptor *d, const fd_set *fdset)
{
struct physical *p = descriptor2physical(d);
struct execdevice *dev = device2exec(p->handler);
int result = dev->fd_out >= 0 && FD_ISSET(dev->fd_out, fdset);
result += physical_IsSet(d, fdset);
return result;
}
struct device *
exec_Create(struct physical *p)
{
struct execdevice *dev;
dev = NULL;
if (p->fd < 0) {
if (*p->name.full == '!') {
int fids[2], type;
if ((dev = malloc(sizeof *dev)) == NULL) {
log_Printf(LogWARN, "%s: Cannot allocate an exec device: %s\n",
p->link.name, strerror(errno));
return NULL;
}
dev->fd_out = -1;
p->fd--; /* We own the device but maybe can't use it - change fd */
type = physical_IsSync(p) ? SOCK_DGRAM : SOCK_STREAM;
if (socketpair(AF_UNIX, type, PF_UNSPEC, fids) < 0) {
log_Printf(LogPHASE, "Unable to create pipe for line exec: %s\n",
strerror(errno));
free(dev);
dev = NULL;
} else {
static int child_status; /* This variable is abused ! */
int stat, argc, i, ret, wret, pidpipe[2];
pid_t pid, realpid;
char *argv[MAXARGS];
stat = fcntl(fids[0], F_GETFL, 0);
if (stat > 0) {
stat |= O_NONBLOCK;
fcntl(fids[0], F_SETFL, stat);
}
realpid = getpid();
if (pipe(pidpipe) == -1) {
log_Printf(LogPHASE, "Unable to pipe for line exec: %s\n",
strerror(errno));
close(fids[1]);
close(fids[0]);
free(dev);
dev = NULL;
} else switch ((pid = fork())) {
case -1:
log_Printf(LogPHASE, "Unable to fork for line exec: %s\n",
strerror(errno));
close(pidpipe[0]);
close(pidpipe[1]);
close(fids[1]);
close(fids[0]);
break;
case 0:
close(pidpipe[0]);
close(fids[0]);
timer_TermService();
#ifndef NOSUID
setuid(ID0realuid());
#endif
child_status = 0;
switch ((pid = vfork())) {
case 0:
close(pidpipe[1]);
break;
case -1:
ret = errno;
log_Printf(LogPHASE, "Unable to vfork to drop parent: %s\n",
strerror(errno));
close(pidpipe[1]);
_exit(ret);
default:
write(pidpipe[1], &pid, sizeof pid);
close(pidpipe[1]);
_exit(child_status); /* The error from exec() ! */
}
log_Printf(LogDEBUG, "Exec'ing ``%s''\n", p->name.base);
if ((argc = MakeArgs(p->name.base, argv, VECSIZE(argv),
PARSE_REDUCE|PARSE_NOHASH)) < 0) {
log_Printf(LogWARN, "Syntax error in exec command\n");
_exit(ESRCH);
}
command_Expand(argv, argc, (char const *const *)argv,
p->dl->bundle, 0, realpid);
dup2(fids[1], STDIN_FILENO);
dup2(fids[1], STDOUT_FILENO);
dup2(fids[1], STDERR_FILENO);
for (i = getdtablesize(); i > STDERR_FILENO; i--)
fcntl(i, F_SETFD, 1);
execvp(*argv, argv);
child_status = errno; /* Only works for vfork() */
printf("execvp failed: %s: %s\r\n", *argv, strerror(child_status));
_exit(child_status);
break;
default:
close(pidpipe[1]);
close(fids[1]);
if (read(pidpipe[0], &p->session_owner, sizeof p->session_owner) !=
sizeof p->session_owner)
p->session_owner = (pid_t)-1;
close(pidpipe[0]);
while ((wret = waitpid(pid, &stat, 0)) == -1 && errno == EINTR)
;
if (wret == -1) {
log_Printf(LogWARN, "Waiting for child process: %s\n",
strerror(errno));
close(fids[0]);
p->session_owner = (pid_t)-1;
break;
} else if (WIFSIGNALED(stat)) {
log_Printf(LogWARN, "Child process received sig %d !\n",
WTERMSIG(stat));
close(fids[0]);
p->session_owner = (pid_t)-1;
break;
} else if (WIFSTOPPED(stat)) {
log_Printf(LogWARN, "Child process received stop sig %d !\n",
WSTOPSIG(stat));
/* I guess that's ok.... */
} else if ((ret = WEXITSTATUS(stat))) {
log_Printf(LogWARN, "Cannot exec \"%s\": %s\n", p->name.base,
strerror(ret));
close(fids[0]);
p->session_owner = (pid_t)-1;
break;
}
p->fd = fids[0];
log_Printf(LogDEBUG, "Using descriptor %d for child\n", p->fd);
}
}
}
} else {
struct stat st;
if (fstat(p->fd, &st) != -1 && (st.st_mode & S_IFIFO)) {
if ((dev = malloc(sizeof *dev)) == NULL)
log_Printf(LogWARN, "%s: Cannot allocate an exec device: %s\n",
p->link.name, strerror(errno));
else if (p->fd == STDIN_FILENO) {
log_Printf(LogPHASE, "%s: Using stdin/stdout to communicate with "
"parent (pipe mode)\n", p->link.name);
dev->fd_out = dup(STDOUT_FILENO);
/* Hook things up so that we monitor dev->fd_out */
p->desc.UpdateSet = exec_UpdateSet;
p->desc.IsSet = exec_IsSet;
} else
dev->fd_out = -1;
}
}
if (dev) {
memcpy(&dev->dev, &baseexecdevice, sizeof dev->dev);
physical_SetupStack(p, dev->dev.name, PHYSICAL_NOFORCE);
if (p->cfg.cd.necessity != CD_DEFAULT)
log_Printf(LogWARN, "Carrier settings ignored\n");
return &dev->dev;
}
return NULL;
}
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