1  /*
  2   This file is part of Darling.
  3  
  4   Copyright (C) 2019 Lubos Dolezel
  5  
  6   Darling is free software: you can redistribute it and/or modify
  7   it under the terms of the GNU General Public License as published by
  8   the Free Software Foundation, either version 3 of the License, or
  9   (at your option) any later version.
 10  
 11   Darling is distributed in the hope that it will be useful,
 12   but WITHOUT ANY WARRANTY; without even the implied warranty of
 13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14   GNU General Public License for more details.
 15  
 16   You should have received a copy of the GNU General Public License
 17   along with Darling.  If not, see <http://www.gnu.org/licenses/>.
 18  */
 19  
 20  #include <stdlib.h>
 21  #include <unistd.h>
 22  #include <stdio.h>
 23  #include <string.h>
 24  #include <sys/types.h>
 25  
 26  unsigned int firstarg = 1, uid = 0, gid = 0;
 27  
 28  static int list_mode = 0;
 29  
 30  int argparse(int, char**);
 31  int usage(int, int);
 32  
 33  int main(int argc, char **argv)
 34  {
 35  	char *path = getenv("PATH"), *path_orig, *fullpath = NULL;
 36  	int i, len;
 37  	if (argparse(argc, argv))
 38  			return 1;
 39  
 40  	setuid(uid);
 41  	setgid(gid);
 42  
 43  	if (firstarg == argc && list_mode)
 44  	{
 45  		printf("List mode without command not supported yet.\n");
 46  		return EXIT_SUCCESS;
 47  	}
 48  	else if (list_mode)
 49  	{
 50  		/* Print fill path to command, then args if present */
 51  		if (!path)
 52  			printf("can't search for command if no path\n");
 53  		path = strdup(path);
 54  		path_orig = path;
 55  		len = strlen(path_orig);
 56  		for (i = 0; i < len; i++)
 57  		{
 58  			if (path_orig[i] == ':' || path_orig[i] == '\0')
 59  			{
 60  				path_orig[i] = '\0';
 61  				fullpath = malloc(strlen(argv[firstarg])+strlen(path)+2);
 62  				strcpy(fullpath, path);
 63  				fullpath[strlen(path)] = '/';
 64  				strcpy(fullpath+strlen(path)+1, argv[firstarg]);
 65  				if (access(fullpath, X_OK) == 0)
 66  					break;
 67  				free(fullpath);
 68  				fullpath = NULL;
 69  				path = path_orig+i+1;
 70  			}
 71  		}
 72  		free(path_orig);
 73  		if (!fullpath)
 74  		{
 75  			fprintf(stderr, "%s: %s: command not found\n", argv[0], argv[firstarg]);
 76  			return EXIT_FAILURE;
 77  		}
 78  		printf("%s", fullpath);
 79  		free(fullpath);
 80  		for (i = firstarg+1; i < argc; i++)
 81  		{
 82  			printf(" %s", argv[i]);
 83  		}
 84  		putchar('\n');
 85  		return EXIT_SUCCESS;
 86  	}
 87  	else
 88  	{
 89  		if (firstarg < argc)
 90  		{
 91  			execvp(argv[firstarg], &argv[firstarg]);
 92  			perror("Running sudo failed");
 93  		}
 94  		else
 95  			return EXIT_SUCCESS;
 96  	}
 97  	return EXIT_FAILURE;
 98  }
 99  
100  int argparse(int argc, char **argv)
101  {
102  	for (firstarg = 1; firstarg < argc; firstarg++)
103  	{
104  		if(!strcmp(argv[firstarg], "-g"))
105  		{
106  			sscanf(argv[++firstarg], "%u", &gid);
107  		}
108  		else if(!strcmp(argv[firstarg], "-u"))
109  		{
110  			sscanf(argv[++firstarg], "%u", &uid);
111  		}
112  		else if (!strcmp(argv[firstarg], "-A"))
113  		{
114  		}
115  		else if (!strcmp(argv[firstarg], "-n"))
116  		{
117  		}
118  		else if (!strcmp(argv[firstarg], "-v"))
119  		{
120  		}
121  		else if(!strcmp(argv[firstarg], "--"))
122  		{
123  			break;
124  		}
125  		else if(!strcmp(argv[firstarg], "-k"))
126  		{
127  		}
128  		else if(!strcmp(argv[firstarg], "--help"))
129  		{
130  			return usage(argc, 1);
131  		}
132  		else if (!strcmp(argv[firstarg], "-l"))
133  		{
134  			list_mode = 1;
135  		}
136  		else
137  		{
138  			break;
139  		}
140  	}
141  	return 0;
142  }
143  
144  int usage(int argc, int arg_help)
145  {
146  	if (argc <= firstarg || arg_help == 1)
147  	{
148  		fprintf(stderr, "This is a fake 'sudo' implementation, intended for use in Darling.\n"
149  				"Processes will think they are run as UID/GID 0, but they are still run as your original UID/GID.\n"
150  				"One purpose of this program is to convince some tools that they can write into '/'.\n"
151  				"Another is to enable you to talk to certain system daemons.\n"
152  				"\nUsage:\n"
153  				"  sudo [-g GID] [-u UID] [-k] [--] COMMAND\n");
154  		return 1;
155  	}
156  	return 0;
157  }