2 * This module implements a simple but effective form of login access
3 * control based on login names and on host (or domain) names, internet
4 * addresses (or network numbers), or on terminal line names in case of
5 * non-networked logins. Diagnostics are reported through syslog(3).
7 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
9 * $FreeBSD: src/lib/libpam/modules/pam_login_access/login_access.c,v 1.13 2007/05/25 07:50:18 des Exp $
12 #include <sys/types.h>
23 #include "pam_login_access.h"
25 #define _PATH_LOGACCESS "/etc/login.access"
27 /* Delimiters for fields and for lists of users, ttys or hosts. */
29 static char fs[] = ":"; /* field separator */
30 static char sep[] = ", \t"; /* list-element separator */
32 /* Constants to be used in assignments only, not in comparisons... */
37 static int from_match(const char *, const char *);
38 static int list_match(char *, const char *,
39 int (*)(const char *, const char *));
40 static int netgroup_match(const char *, const char *, const char *);
41 static int string_match(const char *, const char *);
42 static int user_match(const char *, const char *);
44 /* login_access - match username/group and host/tty with access control file */
47 login_access(const char *user, const char *from)
51 char *perm; /* becomes permission field */
52 char *users; /* becomes list of login names */
53 char *froms; /* becomes list of terminals or hosts */
56 int lineno = 0; /* for diagnostics */
59 * Process the table one line at a time and stop at the first match.
60 * Blank lines and lines that begin with a '#' character are ignored.
61 * Non-comment lines are broken at the ':' character. All fields are
62 * mandatory. The first field should be a "+" or "-" character. A
63 * non-existing table means no access control.
66 if ((fp = fopen(_PATH_LOGACCESS, "r")) != NULL) {
67 while (!match && fgets(line, sizeof(line), fp)) {
69 if (line[end = strlen(line) - 1] != '\n') {
70 syslog(LOG_ERR, "%s: line %d: missing newline or line too long",
71 _PATH_LOGACCESS, lineno);
75 continue; /* comment line */
76 while (end > 0 && isspace(line[end - 1]))
78 line[end] = 0; /* strip trailing whitespace */
79 if (line[0] == 0) /* skip blank lines */
81 if (!(perm = strtok(line, fs))
82 || !(users = strtok(NULL, fs))
83 || !(froms = strtok(NULL, fs))
84 || strtok(NULL, fs)) {
85 syslog(LOG_ERR, "%s: line %d: bad field count", _PATH_LOGACCESS,
89 if (perm[0] != '+' && perm[0] != '-') {
90 syslog(LOG_ERR, "%s: line %d: bad first field", _PATH_LOGACCESS,
94 match = (list_match(froms, from, from_match)
95 && list_match(users, user, user_match));
98 } else if (errno != ENOENT) {
99 syslog(LOG_ERR, "cannot open %s: %m", _PATH_LOGACCESS);
101 return (match == 0 || (line[0] == '+'));
104 /* list_match - match an item against a list of tokens with exceptions */
107 list_match(char *list, const char *item,
108 int (*match_fn)(const char *, const char *))
114 * Process tokens one at a time. We have exhausted all possible matches
115 * when we reach an "EXCEPT" token or the end of the list. If we do find
116 * a match, look for an "EXCEPT" list and recurse to determine whether
117 * the match is affected by any exceptions.
120 for (tok = strtok(list, sep); tok != 0; tok = strtok(NULL, sep)) {
121 if (strcasecmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */
123 if ((match = (*match_fn)(tok, item)) != 0) /* YES */
126 /* Process exceptions to matches. */
129 while ((tok = strtok(NULL, sep)) && strcasecmp(tok, "EXCEPT"))
131 if (tok == 0 || list_match(NULL, item, match_fn) == NO)
137 /* netgroup_match - match group against machine or user */
140 netgroup_match(const char *group, const char *machine, const char *user)
145 if (getdomainname(domain, sizeof(domain)) != 0 || *domain == '\0') {
146 syslog(LOG_ERR, "NIS netgroup support disabled: no NIS domain");
150 /* getdomainname() does not reliably terminate the string */
151 for (i = 0; i < sizeof(domain); ++i)
152 if (domain[i] == '\0')
154 if (i == sizeof(domain)) {
155 syslog(LOG_ERR, "NIS netgroup support disabled: invalid NIS domain");
159 if (innetgr(group, machine, user, domain) == 1)
164 /* user_match - match a username against one token */
167 user_match(const char *tok, const char *string)
173 * If a token has the magic value "ALL" the match always succeeds.
174 * Otherwise, return YES if the token fully matches the username, or if
175 * the token is a group that contains the username.
178 if (tok[0] == '@') { /* netgroup */
179 return (netgroup_match(tok + 1, NULL, string));
180 } else if (string_match(tok, string)) { /* ALL or exact match */
182 } else if ((group = getgrnam(tok)) != NULL) {/* try group membership */
183 for (i = 0; group->gr_mem[i]; i++)
184 if (strcasecmp(string, group->gr_mem[i]) == 0)
190 /* from_match - match a host or tty against a list of tokens */
193 from_match(const char *tok, const char *string)
199 * If a token has the magic value "ALL" the match always succeeds. Return
200 * YES if the token fully matches the string. If the token is a domain
201 * name, return YES if it matches the last fields of the string. If the
202 * token has the magic value "LOCAL", return YES if the string does not
203 * contain a "." character. If the token is a network number, return YES
204 * if it matches the head of the string.
207 if (tok[0] == '@') { /* netgroup */
208 return (netgroup_match(tok + 1, string, NULL));
209 } else if (string_match(tok, string)) { /* ALL or exact match */
211 } else if (tok[0] == '.') { /* domain: match last fields */
212 if ((str_len = strlen(string)) > (tok_len = strlen(tok))
213 && strcasecmp(tok, string + str_len - tok_len) == 0)
215 } else if (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */
216 if (strchr(string, '.') == 0)
218 } else if (tok[(tok_len = strlen(tok)) - 1] == '.' /* network */
219 && strncmp(tok, string, tok_len) == 0) {
225 /* string_match - match a string against one token */
228 string_match(const char *tok, const char *string)
232 * If the token has the magic value "ALL" the match always succeeds.
233 * Otherwise, return YES if the token fully matches the string.
236 if (strcasecmp(tok, "ALL") == 0) { /* all: always matches */
238 } else if (strcasecmp(tok, string) == 0) { /* try exact match */