1/*-
2 *  perm.c - check user permission for at(1)
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
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/* System Headers */
31
32#include <sys/types.h>
33#include <err.h>
34#include <errno.h>
35#include <pwd.h>
36#include <stddef.h>
37#include <stdio.h>
38#include <stdlib.h>
39#include <string.h>
40#include <unistd.h>
41
42/* Local headers */
43
44#include "at.h"
45#include "perm.h"
46#include "privs.h"
47
48/* Macros */
49
50#define MAXUSERID 10
51
52/* Structures and unions */
53
54/* Function declarations */
55
56static int check_for_user(FILE *fp,const char *name);
57
58/* Local functions */
59
60static int check_for_user(FILE *fp,const char *name)
61{
62    char *buffer;
63    size_t len;
64    int found = 0;
65
66    len = strlen(name);
67    if ((buffer = malloc(len+2)) == NULL)
68	errx(EXIT_FAILURE, "virtual memory exhausted");
69
70    while(fgets(buffer, len+2, fp) != NULL)
71    {
72	if ((strncmp(name, buffer, len) == 0) &&
73	    (buffer[len] == '\n'))
74	{
75	    found = 1;
76	    break;
77	}
78    }
79    fclose(fp);
80    free(buffer);
81    return found;
82}
83/* Global functions */
84int check_permission(void)
85{
86    FILE *fp;
87    uid_t uid = geteuid();
88    struct passwd *pentry;
89
90    if (uid==0)
91	return 1;
92
93    if ((pentry = getpwuid(uid)) == NULL)
94	err(EXIT_FAILURE, "cannot access user database");
95
96    PRIV_START
97
98    fp=fopen(PERM_PATH "at.allow","r");
99
100    PRIV_END
101
102    if (fp != NULL)
103    {
104	return check_for_user(fp, pentry->pw_name);
105    }
106    else if (errno == ENOENT)
107    {
108
109	PRIV_START
110
111	fp=fopen(PERM_PATH "at.deny", "r");
112
113	PRIV_END
114
115	if (fp != NULL)
116	{
117	    return !check_for_user(fp, pentry->pw_name);
118	}
119	else if (errno != ENOENT)
120	    warn("at.deny");
121    }
122    else
123	warn("at.allow");
124    return 0;
125}
126