minix3/commands/rshd/rshd.c

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2020-02-21 00:59:27 +05:30
/*
in.rshd.c
*/
/*
main channel:
back channel\0
remuser\0
locuser\0
command\0
data
back channel:
signal\0
*/
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <net/gen/in.h>
#include <net/gen/inet.h>
#include <netdb.h>
#include <net/gen/socket.h>
#include <net/gen/tcp.h>
#include <net/gen/tcp_io.h>
#include <net/hton.h>
#include <net/netlib.h>
#define DEBUG 0
#if DEBUG
#define where() fprintf(stderr, "%s, %d: ", __FILE__, __LINE__)
#endif
char cmdbuf[_POSIX_ARG_MAX+1], locuser[16], remuser[16];
extern char **environ;
char username[20]="USER=";
char homedir[64]="HOME=";
char shell[64]="SHELL=";
char tz[1024]="TZ=";
char *envinit[]= {homedir, shell, username, tz, "PATH=:/bin:/usr/bin", 0};
char *prog_name;
char buffer[PIPE_BUF];
#if __STDC__
#define PROTO(func, args) func args
#else
#define PROTO(func, args) func ()
#endif
PROTO (int main, (int argc, char *argv[]));
PROTO (void getstr, (char*buf, int cnt, char *err));
PROTO (void close_on_exec, (int fd));
int main(argc, argv)
int argc;
char *argv[];
{
int result, result1;
nwio_tcpconf_t tcpconf, err_tcpconf;
nwio_tcpcl_t tcpconnopt;
nwio_tcpatt_t tcpattachopt;
tcpport_t tcpport;
tcpport_t err_port;
int err_fd, pds[2];
pid_t pid, pid1, new_pg;
#if USEATTACH
int err2_fd;
#endif
struct passwd *pwent;
char *cp, *buff_ptr, *TZ;
char sig;
prog_name= argv[0];
if (argc != 1)
{
fprintf(stderr, "%s: wrong number of arguments (%d)\n",
prog_name, argc);
exit(1);
}
signal(SIGINT, SIG_DFL);
signal(SIGQUIT, SIG_DFL);
signal(SIGTERM, SIG_DFL);
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (0, NWIOGTCPCONF, &tcpconf);
if (result<0)
{
fprintf(stderr, "%s: ioctl(NWIOGTCPCONF)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
tcpport= ntohs(tcpconf.nwtc_remport);
if (tcpport >= TCPPORT_RESERVED || tcpport < TCPPORT_RESERVED/2)
{
printf("\1%s: unprotected port (%d)\n", prog_name, tcpport);
exit(1);
}
alarm(60);
err_port= 0;
for (;;)
{
char c;
result= read(0, &c, 1);
if (result <0)
{
fprintf(stderr, "%s: read= %d : %s\n", prog_name,
errno, strerror(errno));
}
if (result<1)
exit(1);
if (c == 0)
break;
err_port= err_port*10 + c - '0';
}
alarm(0);
if (err_port != 0)
{
int n, pid, lport;
pid= getpid();
lport= 1;
do {
lport= (lport << 1) | (pid & 1);
pid >>= 1;
} while (lport < TCPPORT_RESERVED/2);
n= TCPPORT_RESERVED/2;
do
{
if (--lport < TCPPORT_RESERVED/2)
lport= TCPPORT_RESERVED-1;
err_fd= open ("/dev/tcp", O_RDWR);
if (err_fd<0)
{
fprintf(stderr, "%s: open= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
close_on_exec(err_fd);
err_tcpconf.nwtc_flags= NWTC_LP_SET | NWTC_SET_RA |
NWTC_SET_RP | NWTC_EXCL;
err_tcpconf.nwtc_locport= htons(lport);
err_tcpconf.nwtc_remport= htons(err_port);
err_tcpconf.nwtc_remaddr= tcpconf.nwtc_remaddr;
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (err_fd, NWIOSTCPCONF, &err_tcpconf);
if (result == 0) break;
if (errno != EADDRINUSE)
{
fprintf(stderr,
"%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
close(err_fd);
} while (--n > 0);
if (n == 0)
{
printf("\1can't get stderr port\n");
exit(1);
}
err_tcpconf.nwtc_flags= NWTC_SHARED;
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (err_fd, NWIOSTCPCONF, &err_tcpconf);
if (result<0)
{
fprintf(stderr,
"%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
tcpconnopt.nwtcl_flags= 0;
n= 20;
for (;;)
{
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (err_fd, NWIOTCPCONN, &tcpconnopt);
if (result == 0) break;
if (errno != EAGAIN && errno != ECONNREFUSED)
{
fprintf(stderr,
"%s: ioctl(NWIOTCPCONN)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
if (--n == 0) break;
sleep(1);
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
}
#if USEATTACH
err2_fd= open ("/dev/tcp", O_RDWR);
close_on_exec(err2_fd);
if (err2_fd<0)
{
fprintf(stderr, "%s: open= %d : %s\n", errno,
prog_name, strerror(errno));
exit(1);
}
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (err2_fd, NWIOSTCPCONF, &err_tcpconf);
if (result<0)
{
fprintf(stderr, "%s: ioctl(NWIOSTCPCONF)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
tcpattachopt.nwta_flags= 0;
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
result= ioctl (err2_fd, NWIOTCPATTACH, &tcpattachopt);
if (result<0)
{
fprintf(stderr, "%s: ioctl(NWIOTCPATTACH)= %d : %s\n",
prog_name, errno, strerror(errno));
exit(1);
}
#if DEBUG
{ where(); fprintf(stderr, "\n"); }
#endif
#endif
}
getstr(remuser, sizeof(remuser), "remuser");
getstr(locuser, sizeof(locuser), "locuser");
getstr(cmdbuf, sizeof(cmdbuf), "cmdbuf");
setpwent();
pwent= getpwnam(locuser);
if (!pwent)
{
printf("\1Login incorrect.\n");
exit(1);
}
endpwent();
if (chdir(pwent->pw_dir) < 0)
{
chdir("/");
}
#if DEBUG
{ where(); fprintf(stderr, "calling iruserok(%s, %d, %s, %s)\n",
inet_ntoa(tcpconf.nwtc_remaddr), 0, remuser, locuser); }
#endif
if (iruserok(tcpconf.nwtc_remaddr, 0, remuser, locuser) < 0)
{
printf("\1Permission denied.\n");
exit(1);
}
if (err_port)
{
/* Let's go to a different process group. */
new_pg= setsid();
pid= fork();
if (pid<0)
{
if (errno != EAGAIN)
{
fprintf(stderr, "%s: fork()= %d : %s\n",
prog_name, errno, strerror(errno));
}
printf("\1Try again.\n");
exit(1);
}
if (pid)
{
close(0); /* stdin */
close(1); /* stdout */
#if USEATTACH
close(err_fd); /* stderr for shell */
#endif
dup2(2,0);
dup2(2,1);
for (;;)
{
#if !USEATTACH
if (read(err_fd, &sig, 1) <= 0)
#else
if (read(err2_fd, &sig, 1) <= 0)
#endif
{
#if 0
printf("read failed: %d\n", errno);
#endif
exit(0);
}
pid= 0;
#if 0
printf("killing %d with %d\n", -new_pg, sig);
#endif
kill(-new_pg, sig);
}
}
#if USEATTACH
close(err2_fd); /* signal channel for parent */
#endif
result= pipe(pds);
if (result<0)
{
printf("\1Can't make pipe\n");
kill(getppid(), SIGTERM);
exit(1);
}
pid1= fork();
if (pid1<0)
{
if (errno != EAGAIN)
{
fprintf(stderr, "%s: fork()= %d : %s\n",
prog_name, errno, strerror(errno));
}
printf("\1Try again.\n");
kill(-new_pg, SIGTERM);
exit(1);
}
if (pid1)
{
close(pds[1]); /* write side of pipe */
for (;;)
{
result= read(pds[0], buffer, sizeof(buffer));
if (result<=0)
{
kill(pid, SIGTERM);
exit(0);
}
buff_ptr= buffer;
while (result>0)
{
result1= write (err_fd, buff_ptr,
result);
if (result1 <= 0)
{
fprintf(stderr,
"%s: write()= %d : %s\n",
prog_name, errno,
strerror(errno));
kill(-new_pg, SIGTERM);
exit(1);
}
result -= result1;
}
}
}
close(err_fd); /* file descriptor for error channel */
close (pds[0]); /* read side of pipe */
dup2(pds[1], 2);
close (pds[1]); /* write side of pipe */
}
if (*pwent->pw_shell == '\0')
pwent->pw_shell= "/bin/sh";
#if __minix_vmd
initgroups(pwent->pw_name, pwent->pw_gid);
#endif
setgid(pwent->pw_gid);
setuid(pwent->pw_uid);
TZ=getenv("TZ");
environ= envinit;
strncat(homedir, pwent->pw_dir, sizeof(homedir)-6);
strncat(shell, pwent->pw_shell, sizeof(shell)-7);
strncat(username, pwent->pw_name, sizeof(username)-6);
if (TZ)
strncat(tz, TZ, sizeof(tz)-4);
else
envinit[3]= NULL;
cp= strrchr(pwent->pw_shell, '/');
if (cp)
cp++;
else
cp= pwent->pw_shell;
if (!err_port)
dup2(1, 2);
write(1, "\0", 1);
execl(pwent->pw_shell, cp, "-c", cmdbuf, 0);
close(2);
open("/dev/tty", O_RDWR);
fprintf(stderr, "%s: execl(%s, %s, .., %s)= %d : %s\n", prog_name,
pwent->pw_shell, cp, cmdbuf, errno, strerror(errno));
kill(getppid(), SIGTERM);
exit(1);
}
void getstr(buf, cnt, err)
char *buf;
int cnt;
char *err;
{
char c;
do
{
if (read(0, &c, 1) != 1)
exit(1);
*buf++ = c;
if (--cnt == 0)
{
printf("\1%s too long", err);
exit(1);
}
} while (c != 0);
}
void close_on_exec(fd)
int fd;
{
(void) fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
}