perm.c revision 7767 
1/*
2 *  perm.c - check user permission for at(1)
3 *  Copyright (C) 1994  Thomas Koenig
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. The name of the author(s) may not be used to endorse or promote
11 *    products derived from this software without specific prior written
12 *    permission.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26/* System Headers */
27
28#include <sys/types.h>
29#include <errno.h>
30#include <pwd.h>
31#include <stddef.h>
32#include <stdio.h>
33#include <stdlib.h>
34#include <string.h>
35#include <unistd.h>
36
37/* Local headers */
38
39#include "privs.h"
40#include "at.h"
41
42/* Macros */
43
44#define MAXUSERID 10
45
46/* Structures and unions */
47
48
49/* File scope variables */
50
51static char rcsid[] = "$Id: perm.c,v 1.1 1994/05/10 18:23:08 kernel Exp $";
52
53/* Function declarations */
54
55static int check_for_user(FILE *fp,const char *name);
56
57/* Local functions */
58
59static int check_for_user(FILE *fp,const char *name)
60{
61    char *buffer;
62    size_t len;
63    int found = 0;
64
65    len = strlen(name);
66    buffer = mymalloc(len+2);
67
68    while(fgets(buffer, len+2, fp) != NULL)
69    {
70	if ((strncmp(name, buffer, len) == 0) &&
71	    (buffer[len] == '\n'))
72	{
73	    found = 1;
74	    break;
75	}
76    }
77    fclose(fp);
78    free(buffer);
79    return found;
80}
81/* Global functions */
82int check_permission()
83{
84    FILE *fp;
85    uid_t uid = geteuid();
86    struct passwd *pentry;
87
88    if (uid==0)
89	return 1;
90
91    if ((pentry = getpwuid(uid)) == NULL)
92    {
93	perror("Cannot access user database");
94	exit(EXIT_FAILURE);
95    }
96
97    PRIV_START
98
99    fp=fopen(PERM_PATH "at.allow","r");
100
101    PRIV_END
102
103    if (fp != NULL)
104    {
105	return check_for_user(fp, pentry->pw_name);
106    }
107    else
108    {
109
110	PRIV_START
111
112	fp=fopen(PERM_PATH "at.deny", "r");
113
114	PRIV_END
115
116	if (fp != NULL)
117	{
118	    return !check_for_user(fp, pentry->pw_name);
119	}
120	perror("at.deny");
121    }
122    return 0;
123}
124