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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#ifdef SOLARIS
#include <stropts.h>
#else
#include <sys/ioctl.h>
#endif
#include <stdio.h>
#include <errno.h>
#define MAX_PASSWORD_LENGTH 64
#define MAX_CMD_LENGTH 256
void usage() {
fprintf(stderr, "Usage: \n");
fprintf(stderr, " ./privp user privs pid\n");
}
/*
* Kind of wrapper for /sbin/su command.
* Usage:
* privp user privs pid
*
* As an argument it takes pid of process that needs to get privileges privs.
* Then it reads password (to pass to /sbin/su) from stdin
*
*/
int main(int argc, char** argv) {
if (argc < 4) {
usage();
exit(1);
}
char readPassword = 1;
/*
* setsid(2) - creates a new session, if the calling process
* is not a process group leader. Upon return the calling process
* will be the session leader of this new session,
* will be the process group leader of a new process group,
* and will have no controlling terminal.
*/
pid_t gid = setsid();
if (gid == -1) {
// The calling process is already a process group leader
// We already have controlling terminal (?)
readPassword = 0;
}
/*
* /dev/ptmx - a character file used to create a pseudo-terminal master
* and slave pair
*/
int master_fd = open("/dev/ptmx", O_RDWR);
if (master_fd == -1) {
fprintf(stderr, "Cannot open /dev/ptmx\n");
perror(NULL);
exit(1);
}
/*
* Before opening the pseudo-terminal slave, you must pass the master's
* file descriptor to grantpt(3) and unlockpt(3).
*/
if (grantpt(master_fd) == -1) {
fprintf(stderr, "grantpt() failed\n");
perror(NULL);
exit(1);
}
if (unlockpt(master_fd) == -1) {
fprintf(stderr, "unlockpt() failed\n");
perror(NULL);
exit(1);
}
char *slave_name = ptsname(master_fd);
if (slave_name == NULL) {
fprintf(stderr, "Cannot get name of slave pseudo-terminal device\n");
perror(NULL);
exit(1);
}
int slave_fd = open(slave_name, O_RDWR);
#if defined (__SVR4) && defined (__sun)
/*
* ptem(7M) - STREAMS Pseudo Terminal Emulation module
* ptem is a STREAMS module that, when used in conjunction with
* a line discipline and pseudo terminal driver, emulates a terminal.
*
* The ptem module must be pushed onto the slave side of a pseudo terminal
* STREAM, before the ldterm(7M) module is pushed.
*
*/
ioctl(slave_fd, I_PUSH, "ptem");
/*
* ldterm(7M) - standard STREAMS terminal line discipline module
*
* The ldterm STREAMS module provides most of the termio(7I)
* terminal interface.
*/
ioctl(slave_fd, I_PUSH, "ldterm");
/*
* Read password from stdin and write it to master_fd ...
*/
#endif
if (readPassword == 1) {
char pwd[MAX_PASSWORD_LENGTH];
int passwdLength = read(STDIN_FILENO, pwd, MAX_PASSWORD_LENGTH);
int result = write(master_fd, pwd, passwdLength);
// Clear password...
memset(pwd, 0, MAX_PASSWORD_LENGTH);
if (result == -1) {
fprintf(stderr, "Cannot redirect pwd\n");
perror(NULL);
exit(1);
}
}
char command[MAX_CMD_LENGTH];
sprintf(command, "/bin/ppriv -s A+%s %s", argv[2], argv[3]);
/*
* exec(2) -
* ...
* The new process also inherits the following attributes from
* the calling process:
* ...
* session membership
* controlling terminal
* ...
*/
execlp("/sbin/su", "-", argv[1], "-c", command, NULL);
return (EXIT_SUCCESS);
}
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