1/*-
2 *  perm.c - check user permission for at(1)
3 *
4 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
5 *
6 *  Copyright (C) 1994  Thomas Koenig
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. The name of the author(s) may not be used to endorse or promote
14 *    products derived from this software without specific prior written
15 *    permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32/* System Headers */
33
34#include <sys/types.h>
35#include <err.h>
36#include <errno.h>
37#include <pwd.h>
38#include <stddef.h>
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42#include <unistd.h>
43
44/* Local headers */
45
46#include "at.h"
47#include "perm.h"
48#include "privs.h"
49
50/* Macros */
51
52#define MAXUSERID 10
53
54/* Structures and unions */
55
56/* Function declarations */
57
58static int check_for_user(FILE *fp,const char *name);
59
60/* Local functions */
61
62static int check_for_user(FILE *fp,const char *name)
63{
64    char *buffer;
65    size_t len;
66    int found = 0;
67
68    len = strlen(name);
69    if ((buffer = malloc(len+2)) == NULL)
70	errx(EXIT_FAILURE, "virtual memory exhausted");
71
72    while(fgets(buffer, len+2, fp) != NULL)
73    {
74	if ((strncmp(name, buffer, len) == 0) &&
75	    (buffer[len] == '\n'))
76	{
77	    found = 1;
78	    break;
79	}
80    }
81    fclose(fp);
82    free(buffer);
83    return found;
84}
85/* Global functions */
86int check_permission(void)
87{
88    FILE *fp;
89    uid_t uid = geteuid();
90    struct passwd *pentry;
91
92    if (uid==0)
93	return 1;
94
95    if ((pentry = getpwuid(uid)) == NULL)
96	err(EXIT_FAILURE, "cannot access user database");
97
98    PRIV_START
99
100    fp=fopen(PERM_PATH "at.allow","r");
101
102    PRIV_END
103
104    if (fp != NULL)
105    {
106	return check_for_user(fp, pentry->pw_name);
107    }
108    else if (errno == ENOENT)
109    {
110
111	PRIV_START
112
113	fp=fopen(PERM_PATH "at.deny", "r");
114
115	PRIV_END
116
117	if (fp != NULL)
118	{
119	    return !check_for_user(fp, pentry->pw_name);
120	}
121	else if (errno != ENOENT)
122	    warn("at.deny");
123    }
124    else
125	warn("at.allow");
126    return 0;
127}
128