aboutsummaryrefslogtreecommitdiffstats
path: root/src/cerberus.c
blob: 2199d7bb5ff867dc44f560497a348cac80f34d8f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
/**
 * cerberus – Minimal login program
 * 
 * Copyright © 2013  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program 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 3 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "cerberus.h"


/**
 * Mane method
 * 
 * @param   argc  The number of command line arguments
 * @param   argv  The command line arguments
 * @return        Return code
 */
int main(int argc, char** argv)
{
  char* username = NULL;
  char* hostname = NULL;
  char* passphrase = NULL;
  char preserve_env = 0;
  char skip_auth = 0;
  struct passwd* entry;
  
  
  /* Disable echoing */
  disable_echo();
  /* This should be done as early and quickly as possible so as little
     as possible of the passphrase gets leaked to the output if the user
     begins entering the passphrase directly after the username. */
  
  
  /* Set process group ID */
  setpgrp();
  
  
  /* Parse command line arguments */
  {
    char double_dashed = 0;
    char hostname_on_next = 0;
    int i;
    for (i = 1; i < argc; i++)
      {
	char *arg = *(argv + i);
	char c;
	
	if (*arg == 0)
	  ;
	else if ((*arg == '-') && (double_dashed == 0))
	  while ((c = *(++arg)))
	    if ((c == 'V') || (c == 'H'))
	      ;
	    else if (c == 'p')
	      preserve_env = 1;
	    else if (c == 'h')
	      {
		if (*(arg + 1))
		  hostname = arg + 1;
		else
		  hostname_on_next = 1;
		break;
	      }
	    else if (c == 'f')
	      {
		if (*(arg + 1))
		  username = arg + 1;
		skip_auth = 1;
		break;
	      }
	    else if (c == '-')
	      {
		double_dashed = 1;
		break;
	      }
	    else
	      printf("%s: unrecognised options: -%c\n", *argv, c);
	else if (hostname_on_next)
	  {
	    hostname = arg;
	    hostname_on_next = 0;
	  }
	else
	  username = arg;
      }
  }
  
  
  /* Change that a username has been specified */
  if (username == 0)
    {
      printf("%s: no username specified\n", *argv);
      sleep(ERROR_SLEEP);
      return 2;
    }
  
  
  /* Print ant we want a passphrase, if -f has not been used */
  if (skip_auth == 0)
    {
      printf("Passphrase: ");
      fflush(stdout);
    }
  /* Done early to make to program look like it is even faster than it is */
  
  
  /* Make sure nopony is spying */
  secure_tty();
  
  
  /* Set up clean quiting and time out */
  signal(SIGALRM, timeout_quit);
  signal(SIGQUIT, user_quit);
  signal(SIGINT, user_quit);
  siginterrupt(SIGALRM, 1);
  siginterrupt(SIGQUIT, 1);
  siginterrupt(SIGINT, 1);
  alarm(TIMEOUT_SECONDS);
  
  
  /* Get user information */
  if ((entry = getpwnam(username)) == NULL)
    {
      if (errno)
	perror("getpwnam");
      else
	printf("User does not exist\n");
      sleep(ERROR_SLEEP);
      return 1;
    }
  
  
  /* Get the passphrase, if -f has not been used */
  if (skip_auth == 0)
    {
      passphrase = get_passphrase();
      printf("\n");
    }
  
  /* Passphrase entered, turn off timeout */
  alarm(0);
  
  /* Wipe and free the passphrase from the memory */
  if (skip_auth == 0)
    {
      long i;
      for (i = 0; *(passphrase + i); i++)
	*(passphrase + i) = 0;
      free(passphrase);
    }
  
  
  /* Reset terminal settings */
  reenable_echo();
  
  
  /* TODO login */
  
  
  /* Reset terminal ownership and mode */
  chown_tty(0, -1, 0);
  
  return 0;
}