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#include <sys/cdefs.h>
27__FBSDID("$FreeBSD$");
28
29/* System Headers */
30
31#include <sys/types.h>
32#include <err.h>
33#include <errno.h>
34#include <pwd.h>
35#include <stddef.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <string.h>
39#include <unistd.h>
40
41/* Local headers */
42
43#include "at.h"
44#include "perm.h"
45#include "privs.h"
46
47/* Macros */
48
49#define MAXUSERID 10
50
51/* Structures and unions */
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    if ((buffer = malloc(len+2)) == NULL)
67	errx(EXIT_FAILURE, "virtual memory exhausted");
68
69    while(fgets(buffer, len+2, fp) != NULL)
70    {
71	if ((strncmp(name, buffer, len) == 0) &&
72	    (buffer[len] == '\n'))
73	{
74	    found = 1;
75	    break;
76	}
77    }
78    fclose(fp);
79    free(buffer);
80    return found;
81}
82/* Global functions */
83int check_permission(void)
84{
85    FILE *fp;
86    uid_t uid = geteuid();
87    struct passwd *pentry;
88
89    if (uid==0)
90	return 1;
91
92    if ((pentry = getpwuid(uid)) == NULL)
93	err(EXIT_FAILURE, "cannot access user database");
94
95    PRIV_START
96
97    fp=fopen(PERM_PATH "at.allow","r");
98
99    PRIV_END
100
101    if (fp != NULL)
102    {
103	return check_for_user(fp, pentry->pw_name);
104    }
105    else if (errno == ENOENT)
106    {
107
108	PRIV_START
109
110	fp=fopen(PERM_PATH "at.deny", "r");
111
112	PRIV_END
113
114	if (fp != NULL)
115	{
116	    return !check_for_user(fp, pentry->pw_name);
117	}
118	else if (errno != ENOENT)
119	    warn("at.deny");
120    }
121    else
122	warn("at.allow");
123    return 0;
124}
125