login_access.c revision 87177
1290001Sglebius /* 2290001Sglebius * This module implements a simple but effective form of login access 3290001Sglebius * control based on login names and on host (or domain) names, internet 4290001Sglebius * addresses (or network numbers), or on terminal line names in case of 5290001Sglebius * non-networked logins. Diagnostics are reported through syslog(3). 6290001Sglebius * 7290001Sglebius * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 8290001Sglebius * $FreeBSD: head/lib/libpam/modules/pam_login_access/login_access.c 87177 2001-12-01 21:12:04Z markm $ 9132451Sroberto */ 10132451Sroberto 11290001Sglebius#ifdef LOGIN_ACCESS 12290001Sglebius#ifndef lint 13132451Srobertostatic const char sccsid[] = "%Z% %M% %I% %E% %U%"; 14132451Sroberto#endif 15132451Sroberto 16290001Sglebius#include <sys/types.h> 17132451Sroberto#include <ctype.h> 18290001Sglebius#include <errno.h> 19132451Sroberto#include <grp.h> 20132451Sroberto#include <stdio.h> 21132451Sroberto#include <stdlib.h> 22132451Sroberto#include <string.h> 23132451Sroberto#include <syslog.h> 24132451Sroberto#include <unistd.h> 25132451Sroberto 26132451Sroberto#include "login.h" 27132451Sroberto#include "pathnames.h" 28132451Sroberto 29290001Sglebius /* Delimiters for fields and for lists of users, ttys or hosts. */ 30132451Sroberto 31290001Sglebiusstatic char fs[] = ":"; /* field separator */ 32132451Srobertostatic char sep[] = ", \t"; /* list-element separator */ 33290001Sglebius 34290001Sglebius /* Constants to be used in assignments only, not in comparisons... */ 35290001Sglebius 36290001Sglebius#define YES 1 37290001Sglebius#define NO 0 38290001Sglebius 39290001Sglebiusstatic int from_match __P((char *, char *)); 40290001Sglebiusstatic int list_match __P((char *, char *, int (*)(char *, char *))); 41290001Sglebiusstatic int netgroup_match __P((char *, char *, char *)); 42290001Sglebiusstatic int string_match __P((char *, char *)); 43290001Sglebiusstatic int user_match __P((char *, char *)); 44290001Sglebius 45290001Sglebius/* login_access - match username/group and host/tty with access control file */ 46290001Sglebius 47290001Sglebiusint 48290001Sglebiuslogin_access(user, from) 49290001Sglebiuschar *user; 50290001Sglebiuschar *from; 51290001Sglebius{ 52132451Sroberto FILE *fp; 53290001Sglebius char line[BUFSIZ]; 54290001Sglebius char *perm; /* becomes permission field */ 55290001Sglebius char *users; /* becomes list of login names */ 56132451Sroberto char *froms; /* becomes list of terminals or hosts */ 57290001Sglebius int match = NO; 58290001Sglebius int end; 59290001Sglebius int lineno = 0; /* for diagnostics */ 60290001Sglebius 61132451Sroberto /* 62132451Sroberto * Process the table one line at a time and stop at the first match. 63290001Sglebius * Blank lines and lines that begin with a '#' character are ignored. 64290001Sglebius * Non-comment lines are broken at the ':' character. All fields are 65290001Sglebius * mandatory. The first field should be a "+" or "-" character. A 66132451Sroberto * non-existing table means no access control. 67290001Sglebius */ 68290001Sglebius 69290001Sglebius if ((fp = fopen(_PATH_LOGACCESS, "r")) != NULL) { 70290001Sglebius while (!match && fgets(line, sizeof(line), fp)) { 71290001Sglebius lineno++; 72290001Sglebius if (line[end = strlen(line) - 1] != '\n') { 73132451Sroberto syslog(LOG_ERR, "%s: line %d: missing newline or line too long", 74132451Sroberto _PATH_LOGACCESS, lineno); 75132451Sroberto continue; 76132451Sroberto } 77132451Sroberto if (line[0] == '#') 78290001Sglebius continue; /* comment line */ 79290001Sglebius while (end > 0 && isspace(line[end - 1])) 80290001Sglebius end--; 81290001Sglebius line[end] = 0; /* strip trailing whitespace */ 82290001Sglebius if (line[0] == 0) /* skip blank lines */ 83290001Sglebius continue; 84290001Sglebius if (!(perm = strtok(line, fs)) 85290001Sglebius || !(users = strtok((char *) 0, fs)) 86290001Sglebius || !(froms = strtok((char *) 0, fs)) 87290001Sglebius || strtok((char *) 0, fs)) { 88290001Sglebius syslog(LOG_ERR, "%s: line %d: bad field count", _PATH_LOGACCESS, 89132451Sroberto lineno); 90290001Sglebius continue; 91132451Sroberto } 92132451Sroberto if (perm[0] != '+' && perm[0] != '-') { 93290001Sglebius syslog(LOG_ERR, "%s: line %d: bad first field", _PATH_LOGACCESS, 94132451Sroberto lineno); 95290001Sglebius continue; 96290001Sglebius } 97290001Sglebius match = (list_match(froms, from, from_match) 98290001Sglebius && list_match(users, user, user_match)); 99290001Sglebius } 100290001Sglebius (void) fclose(fp); 101290001Sglebius } else if (errno != ENOENT) { 102290001Sglebius syslog(LOG_ERR, "cannot open %s: %m", _PATH_LOGACCESS); 103132451Sroberto } 104290001Sglebius return (match == 0 || (line[0] == '+')); 105132451Sroberto} 106290001Sglebius 107290001Sglebius/* list_match - match an item against a list of tokens with exceptions */ 108290001Sglebius 109290001Sglebiusstatic int list_match(list, item, match_fn) 110290001Sglebiuschar *list; 111290001Sglebiuschar *item; 112290001Sglebiusint (*match_fn) __P((char *, char *)); 113290001Sglebius{ 114290001Sglebius char *tok; 115290001Sglebius int match = NO; 116290001Sglebius 117290001Sglebius /* 118290001Sglebius * Process tokens one at a time. We have exhausted all possible matches 119290001Sglebius * when we reach an "EXCEPT" token or the end of the list. If we do find 120290001Sglebius * a match, look for an "EXCEPT" list and recurse to determine whether 121290001Sglebius * the match is affected by any exceptions. 122290001Sglebius */ 123290001Sglebius 124290001Sglebius for (tok = strtok(list, sep); tok != 0; tok = strtok((char *) 0, sep)) { 125290001Sglebius if (strcasecmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */ 126290001Sglebius break; 127290001Sglebius if ((match = (*match_fn)(tok, item)) != NULL) /* YES */ 128290001Sglebius break; 129290001Sglebius } 130290001Sglebius /* Process exceptions to matches. */ 131290001Sglebius 132290001Sglebius if (match != NO) { 133290001Sglebius while ((tok = strtok((char *) 0, sep)) && strcasecmp(tok, "EXCEPT")) 134290001Sglebius /* VOID */ ; 135290001Sglebius if (tok == 0 || list_match((char *) 0, item, match_fn) == NO) 136290001Sglebius return (match); 137290001Sglebius } 138290001Sglebius return (NO); 139290001Sglebius} 140290001Sglebius 141290001Sglebius/* netgroup_match - match group against machine or user */ 142290001Sglebius 143290001Sglebiusstatic int netgroup_match(group, machine, user) 144290001Sglebiuschar *group __unused; 145290001Sglebiuschar *machine __unused; 146290001Sglebiuschar *user __unused; 147{ 148 syslog(LOG_ERR, "NIS netgroup support not configured"); 149 return 0; 150} 151 152/* user_match - match a username against one token */ 153 154static int user_match(tok, string) 155char *tok; 156char *string; 157{ 158 struct group *group; 159 int i; 160 161 /* 162 * If a token has the magic value "ALL" the match always succeeds. 163 * Otherwise, return YES if the token fully matches the username, or if 164 * the token is a group that contains the username. 165 */ 166 167 if (tok[0] == '@') { /* netgroup */ 168 return (netgroup_match(tok + 1, (char *) 0, string)); 169 } else if (string_match(tok, string)) { /* ALL or exact match */ 170 return (YES); 171 } else if ((group = getgrnam(tok)) != NULL) {/* try group membership */ 172 for (i = 0; group->gr_mem[i]; i++) 173 if (strcasecmp(string, group->gr_mem[i]) == 0) 174 return (YES); 175 } 176 return (NO); 177} 178 179/* from_match - match a host or tty against a list of tokens */ 180 181static int from_match(tok, string) 182char *tok; 183char *string; 184{ 185 int tok_len; 186 int str_len; 187 188 /* 189 * If a token has the magic value "ALL" the match always succeeds. Return 190 * YES if the token fully matches the string. If the token is a domain 191 * name, return YES if it matches the last fields of the string. If the 192 * token has the magic value "LOCAL", return YES if the string does not 193 * contain a "." character. If the token is a network number, return YES 194 * if it matches the head of the string. 195 */ 196 197 if (tok[0] == '@') { /* netgroup */ 198 return (netgroup_match(tok + 1, string, (char *) 0)); 199 } else if (string_match(tok, string)) { /* ALL or exact match */ 200 return (YES); 201 } else if (tok[0] == '.') { /* domain: match last fields */ 202 if ((str_len = strlen(string)) > (tok_len = strlen(tok)) 203 && strcasecmp(tok, string + str_len - tok_len) == 0) 204 return (YES); 205 } else if (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */ 206 if (strchr(string, '.') == 0) 207 return (YES); 208 } else if (tok[(tok_len = strlen(tok)) - 1] == '.' /* network */ 209 && strncmp(tok, string, tok_len) == 0) { 210 return (YES); 211 } 212 return (NO); 213} 214 215/* string_match - match a string against one token */ 216 217static int string_match(tok, string) 218char *tok; 219char *string; 220{ 221 222 /* 223 * If the token has the magic value "ALL" the match always succeeds. 224 * Otherwise, return YES if the token fully matches the string. 225 */ 226 227 if (strcasecmp(tok, "ALL") == 0) { /* all: always matches */ 228 return (YES); 229 } else if (strcasecmp(tok, string) == 0) { /* try exact match */ 230 return (YES); 231 } 232 return (NO); 233} 234#endif /* LOGIN_ACCES */ 235