perm.c revision 87208 
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(S) 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#ifndef lint
27static const char rcsid[] =
28  "$FreeBSD: head/usr.bin/at/perm.c 87208 2001-12-02 12:26:18Z markm $";
29#endif /* not lint */
30
31/* System Headers */
32
33#include <sys/types.h>
34#include <err.h>
35#include <errno.h>
36#include <pwd.h>
37#include <stddef.h>
38#include <stdio.h>
39#include <stdlib.h>
40#include <string.h>
41#include <unistd.h>
42
43/* Local headers */
44
45#include "at.h"
46#include "perm.h"
47#include "privs.h"
48
49/* Macros */
50
51#define MAXUSERID 10
52
53/* Structures and unions */
54
55/* Function declarations */
56
57static int check_for_user(FILE *fp,const char *name);
58
59/* Local functions */
60
61static int check_for_user(FILE *fp,const char *name)
62{
63    char *buffer;
64    size_t len;
65    int found = 0;
66
67    len = strlen(name);
68    if ((buffer = malloc(len+2)) == NULL)
69	errx(EXIT_FAILURE, "virtual memory exhausted");
70
71    while(fgets(buffer, len+2, fp) != NULL)
72    {
73	if ((strncmp(name, buffer, len) == 0) &&
74	    (buffer[len] == '\n'))
75	{
76	    found = 1;
77	    break;
78	}
79    }
80    fclose(fp);
81    free(buffer);
82    return found;
83}
84/* Global functions */
85int check_permission(void)
86{
87    FILE *fp;
88    uid_t uid = geteuid();
89    struct passwd *pentry;
90
91    if (uid==0)
92	return 1;
93
94    if ((pentry = getpwuid(uid)) == NULL)
95	err(EXIT_FAILURE, "cannot access user database");
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 if (errno == ENOENT)
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	else if (errno != ENOENT)
121	    warn("at.deny");
122    }
123    else
124	warn("at.allow");
125    return 0;
126}
127