1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
|
/*
* This module implements a simple but effective form of login access
* control based on login names and on host (or domain) names, internet
* addresses (or network numbers), or on terminal line names in case of
* non-networked logins. Diagnostics are reported through syslog(3).
*
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
*/
#if 0
#ifndef lint
static char sccsid[] = "%Z% %M% %I% %E% %U%";
#endif
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/param.h>
#include <ctype.h>
#include <errno.h>
#include <grp.h>
#include <netdb.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "pam_login_access.h"
#define _PATH_LOGACCESS "/etc/login.access"
/* Delimiters for fields and for lists of users, ttys or hosts. */
static char fs[] = ":"; /* field separator */
static char sep[] = ", \t"; /* list-element separator */
/* Constants to be used in assignments only, not in comparisons... */
#define YES 1
#define NO 0
static int from_match(const char *, const char *);
static int list_match(char *, const char *,
int (*)(const char *, const char *));
static int netgroup_match(const char *, const char *, const char *);
static int string_match(const char *, const char *);
static int user_match(const char *, const char *);
/* login_access - match username/group and host/tty with access control file */
int
login_access(const char *user, const char *from)
{
FILE *fp;
char line[BUFSIZ];
char *perm; /* becomes permission field */
char *users; /* becomes list of login names */
char *froms; /* becomes list of terminals or hosts */
int match = NO;
int end;
int lineno = 0; /* for diagnostics */
/*
* Process the table one line at a time and stop at the first match.
* Blank lines and lines that begin with a '#' character are ignored.
* Non-comment lines are broken at the ':' character. All fields are
* mandatory. The first field should be a "+" or "-" character. A
* non-existing table means no access control.
*/
if ((fp = fopen(_PATH_LOGACCESS, "r")) != NULL) {
while (!match && fgets(line, sizeof(line), fp)) {
lineno++;
if (line[end = strlen(line) - 1] != '\n') {
syslog(LOG_ERR, "%s: line %d: missing newline or line too long",
_PATH_LOGACCESS, lineno);
continue;
}
if (line[0] == '#')
continue; /* comment line */
while (end > 0 && isspace(line[end - 1]))
end--;
line[end] = 0; /* strip trailing whitespace */
if (line[0] == 0) /* skip blank lines */
continue;
if (!(perm = strtok(line, fs))
|| !(users = strtok((char *) 0, fs))
|| !(froms = strtok((char *) 0, fs))
|| strtok((char *) 0, fs)) {
syslog(LOG_ERR, "%s: line %d: bad field count", _PATH_LOGACCESS,
lineno);
continue;
}
if (perm[0] != '+' && perm[0] != '-') {
syslog(LOG_ERR, "%s: line %d: bad first field", _PATH_LOGACCESS,
lineno);
continue;
}
match = (list_match(froms, from, from_match)
&& list_match(users, user, user_match));
}
(void) fclose(fp);
} else if (errno != ENOENT) {
syslog(LOG_ERR, "cannot open %s: %m", _PATH_LOGACCESS);
}
return (match == 0 || (line[0] == '+'));
}
/* list_match - match an item against a list of tokens with exceptions */
static int
list_match(char *list, const char *item,
int (*match_fn)(const char *, const char *))
{
char *tok;
int match = NO;
/*
* Process tokens one at a time. We have exhausted all possible matches
* when we reach an "EXCEPT" token or the end of the list. If we do find
* a match, look for an "EXCEPT" list and recurse to determine whether
* the match is affected by any exceptions.
*/
for (tok = strtok(list, sep); tok != NULL; tok = strtok((char *) 0, sep)) {
if (strcmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */
break;
if ((match = (*match_fn)(tok, item)) != 0) /* YES */
break;
}
/* Process exceptions to matches. */
if (match != NO) {
while ((tok = strtok((char *) 0, sep)) && strcmp(tok, "EXCEPT"))
/* VOID */ ;
if (tok == NULL || list_match((char *) 0, item, match_fn) == NO)
return (match);
}
return (NO);
}
/* netgroup_match - match group against machine or user */
static int
netgroup_match(const char *group, const char *machine, const char *user)
{
char domain[1024];
unsigned int i;
if (getdomainname(domain, sizeof(domain)) != 0 || *domain == '\0') {
syslog(LOG_ERR, "NIS netgroup support disabled: no NIS domain");
return (NO);
}
/* getdomainname() does not reliably terminate the string */
for (i = 0; i < sizeof(domain); ++i)
if (domain[i] == '\0')
break;
if (i == sizeof(domain)) {
syslog(LOG_ERR, "NIS netgroup support disabled: invalid NIS domain");
return (NO);
}
if (innetgr(group, machine, user, domain) == 1)
return (YES);
return (NO);
}
/* user_match - match a username against one token */
static int
user_match(const char *tok, const char *string)
{
struct group *group;
struct passwd *passwd;
gid_t *grouplist;
int ngroups = NGROUPS;
int i;
/*
* If a token has the magic value "ALL" the match always succeeds.
* Otherwise, return YES if the token fully matches the username, or if
* the token is a group that contains the username.
*/
if (tok[0] == '@') { /* netgroup */
return (netgroup_match(tok + 1, (char *) 0, string));
} else if (string_match(tok, string)) { /* ALL or exact match */
return (YES);
} else {
if ((passwd = getpwnam(string)) == NULL)
return (NO);
errno = 0;
if ((group = getgrnam(tok)) == NULL) {/* try group membership */
if (errno != 0) {
syslog(LOG_ERR, "getgrnam() failed for %s: %s", string, strerror(errno));
} else {
syslog(LOG_NOTICE, "group not found: %s", string);
}
return (NO);
}
errno = 0;
if ((grouplist = calloc(ngroups, sizeof(gid_t))) == NULL) {
if (errno == ENOMEM) {
syslog(LOG_ERR, "cannot allocate memory for grouplist: %s", string);
}
return (NO);
}
if (getgrouplist(string, passwd->pw_gid, grouplist, &ngroups) != 0) {
syslog(LOG_ERR, "getgrouplist() failed for %s", string);
free(grouplist);
return (NO);
}
for (i = 0; i < ngroups; i++) {
if (grouplist[i] == group->gr_gid) {
free(grouplist);
return (YES);
}
}
free(grouplist);
}
return (NO);
}
/* from_match - match a host or tty against a list of tokens */
static int
from_match(const char *tok, const char *string)
{
int tok_len;
int str_len;
/*
* If a token has the magic value "ALL" the match always succeeds. Return
* YES if the token fully matches the string. If the token is a domain
* name, return YES if it matches the last fields of the string. If the
* token has the magic value "LOCAL", return YES if the string does not
* contain a "." character. If the token is a network number, return YES
* if it matches the head of the string.
*/
if (tok[0] == '@') { /* netgroup */
return (netgroup_match(tok + 1, string, (char *) 0));
} else if (string_match(tok, string)) { /* ALL or exact match */
return (YES);
} else if (tok[0] == '.') { /* domain: match last fields */
if ((str_len = strlen(string)) > (tok_len = strlen(tok))
&& strcasecmp(tok, string + str_len - tok_len) == 0)
return (YES);
} else if (strcmp(tok, "LOCAL") == 0) { /* local: no dots */
if (strchr(string, '.') == 0)
return (YES);
} else if (tok[(tok_len = strlen(tok)) - 1] == '.' /* network */
&& strncmp(tok, string, tok_len) == 0) {
return (YES);
}
return (NO);
}
/* string_match - match a string against one token */
static int
string_match(const char *tok, const char *string)
{
/*
* If the token has the magic value "ALL" the match always succeeds.
* Otherwise, return YES if the token fully matches the string.
*/
if (strcmp(tok, "ALL") == 0) { /* all: always matches */
return (YES);
} else if (strcasecmp(tok, string) == 0) { /* try exact match */
return (YES);
}
return (NO);
}
|
