login_access.c revision 169976
12198Sguido /* 22198Sguido * This module implements a simple but effective form of login access 32198Sguido * control based on login names and on host (or domain) names, internet 42198Sguido * addresses (or network numbers), or on terminal line names in case of 52198Sguido * non-networked logins. Diagnostics are reported through syslog(3). 68874Srgrimes * 72198Sguido * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 82198Sguido */ 92198Sguido 1087628Sdwmalone#if 0 112198Sguido#ifndef lint 1287628Sdwmalonestatic char sccsid[] = "%Z% %M% %I% %E% %U%"; 132198Sguido#endif 1487628Sdwmalone#endif 152198Sguido 1687628Sdwmalone#include <sys/cdefs.h> 1787628Sdwmalone__FBSDID("$FreeBSD: head/lib/libpam/modules/pam_login_access/login_access.c 169976 2007-05-25 07:50:18Z des $"); 1887628Sdwmalone 1987177Smarkm#include <sys/types.h> 202198Sguido#include <ctype.h> 2187177Smarkm#include <errno.h> 222198Sguido#include <grp.h> 23169976Sdes#include <netdb.h> 2487177Smarkm#include <stdio.h> 2587177Smarkm#include <stdlib.h> 262198Sguido#include <string.h> 2787177Smarkm#include <syslog.h> 282198Sguido#include <unistd.h> 292198Sguido 3090145Smarkm#include "pam_login_access.h" 3190145Smarkm 3290093Sdes#define _PATH_LOGACCESS "/etc/login.access" 332198Sguido 342198Sguido /* Delimiters for fields and for lists of users, ttys or hosts. */ 352198Sguido 362198Sguidostatic char fs[] = ":"; /* field separator */ 372198Sguidostatic char sep[] = ", \t"; /* list-element separator */ 382198Sguido 392198Sguido /* Constants to be used in assignments only, not in comparisons... */ 402198Sguido 412198Sguido#define YES 1 422198Sguido#define NO 0 432198Sguido 4490145Smarkmstatic int from_match(const char *, const char *); 4590145Smarkmstatic int list_match(char *, const char *, 4690145Smarkm int (*)(const char *, const char *)); 4790145Smarkmstatic int netgroup_match(const char *, const char *, const char *); 4890145Smarkmstatic int string_match(const char *, const char *); 4990145Smarkmstatic int user_match(const char *, const char *); 502198Sguido 512198Sguido/* login_access - match username/group and host/tty with access control file */ 522198Sguido 5322230Spstint 5490145Smarkmlogin_access(const char *user, const char *from) 552198Sguido{ 562198Sguido FILE *fp; 572198Sguido char line[BUFSIZ]; 582198Sguido char *perm; /* becomes permission field */ 592198Sguido char *users; /* becomes list of login names */ 602198Sguido char *froms; /* becomes list of terminals or hosts */ 612198Sguido int match = NO; 622198Sguido int end; 632198Sguido int lineno = 0; /* for diagnostics */ 642198Sguido 652198Sguido /* 662198Sguido * Process the table one line at a time and stop at the first match. 672198Sguido * Blank lines and lines that begin with a '#' character are ignored. 682198Sguido * Non-comment lines are broken at the ':' character. All fields are 692198Sguido * mandatory. The first field should be a "+" or "-" character. A 702198Sguido * non-existing table means no access control. 712198Sguido */ 722198Sguido 7322230Spst if ((fp = fopen(_PATH_LOGACCESS, "r")) != NULL) { 742198Sguido while (!match && fgets(line, sizeof(line), fp)) { 752198Sguido lineno++; 762198Sguido if (line[end = strlen(line) - 1] != '\n') { 772198Sguido syslog(LOG_ERR, "%s: line %d: missing newline or line too long", 782198Sguido _PATH_LOGACCESS, lineno); 792198Sguido continue; 802198Sguido } 812198Sguido if (line[0] == '#') 822198Sguido continue; /* comment line */ 832198Sguido while (end > 0 && isspace(line[end - 1])) 842198Sguido end--; 852198Sguido line[end] = 0; /* strip trailing whitespace */ 862198Sguido if (line[0] == 0) /* skip blank lines */ 872198Sguido continue; 882198Sguido if (!(perm = strtok(line, fs)) 892198Sguido || !(users = strtok((char *) 0, fs)) 902198Sguido || !(froms = strtok((char *) 0, fs)) 912198Sguido || strtok((char *) 0, fs)) { 922198Sguido syslog(LOG_ERR, "%s: line %d: bad field count", _PATH_LOGACCESS, 932198Sguido lineno); 942198Sguido continue; 952198Sguido } 962198Sguido if (perm[0] != '+' && perm[0] != '-') { 972198Sguido syslog(LOG_ERR, "%s: line %d: bad first field", _PATH_LOGACCESS, 982198Sguido lineno); 992198Sguido continue; 1002198Sguido } 1012198Sguido match = (list_match(froms, from, from_match) 1022198Sguido && list_match(users, user, user_match)); 1032198Sguido } 1042198Sguido (void) fclose(fp); 1052198Sguido } else if (errno != ENOENT) { 1062198Sguido syslog(LOG_ERR, "cannot open %s: %m", _PATH_LOGACCESS); 1072198Sguido } 1082198Sguido return (match == 0 || (line[0] == '+')); 1092198Sguido} 1102198Sguido 1112198Sguido/* list_match - match an item against a list of tokens with exceptions */ 1122198Sguido 11390145Smarkmstatic int 11490145Smarkmlist_match(char *list, const char *item, 11590145Smarkm int (*match_fn)(const char *, const char *)) 1162198Sguido{ 1172198Sguido char *tok; 1182198Sguido int match = NO; 1192198Sguido 1202198Sguido /* 1212198Sguido * Process tokens one at a time. We have exhausted all possible matches 1222198Sguido * when we reach an "EXCEPT" token or the end of the list. If we do find 1232198Sguido * a match, look for an "EXCEPT" list and recurse to determine whether 1242198Sguido * the match is affected by any exceptions. 1252198Sguido */ 1262198Sguido 1272198Sguido for (tok = strtok(list, sep); tok != 0; tok = strtok((char *) 0, sep)) { 1282198Sguido if (strcasecmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */ 1292198Sguido break; 130126643Smarkm if ((match = (*match_fn)(tok, item)) != 0) /* YES */ 1312198Sguido break; 1322198Sguido } 1332198Sguido /* Process exceptions to matches. */ 1342198Sguido 1352198Sguido if (match != NO) { 1362198Sguido while ((tok = strtok((char *) 0, sep)) && strcasecmp(tok, "EXCEPT")) 1372198Sguido /* VOID */ ; 1382198Sguido if (tok == 0 || list_match((char *) 0, item, match_fn) == NO) 1392198Sguido return (match); 1402198Sguido } 1412198Sguido return (NO); 1422198Sguido} 1432198Sguido 1442198Sguido/* netgroup_match - match group against machine or user */ 1452198Sguido 14690145Smarkmstatic int 147169976Sdesnetgroup_match(const char *group, const char *machine, const char *user) 1482198Sguido{ 149169976Sdes char domain[1024]; 150169976Sdes unsigned int i; 151169976Sdes 152169976Sdes if (getdomainname(domain, sizeof(domain)) != 0 || *domain == '\0') { 153169976Sdes syslog(LOG_ERR, "NIS netgroup support disabled: no NIS domain"); 154169976Sdes return (NO); 155169976Sdes } 156169976Sdes 157169976Sdes /* getdomainname() does not reliably terminate the string */ 158169976Sdes for (i = 0; i < sizeof(domain); ++i) 159169976Sdes if (domain[i] == '\0') 160169976Sdes break; 161169976Sdes if (i == sizeof(domain)) { 162169976Sdes syslog(LOG_ERR, "NIS netgroup support disabled: invalid NIS domain"); 163169976Sdes return (NO); 164169976Sdes } 165169976Sdes 166169976Sdes if (innetgr(group, machine, user, domain) == 1) 167169976Sdes return (YES); 168169976Sdes return (NO); 1692198Sguido} 1702198Sguido 1712198Sguido/* user_match - match a username against one token */ 1722198Sguido 17390145Smarkmstatic int 17490145Smarkmuser_match(const char *tok, const char *string) 1752198Sguido{ 1762198Sguido struct group *group; 1772198Sguido int i; 1782198Sguido 1792198Sguido /* 1802198Sguido * If a token has the magic value "ALL" the match always succeeds. 1812198Sguido * Otherwise, return YES if the token fully matches the username, or if 1822198Sguido * the token is a group that contains the username. 1832198Sguido */ 1842198Sguido 1852198Sguido if (tok[0] == '@') { /* netgroup */ 1862198Sguido return (netgroup_match(tok + 1, (char *) 0, string)); 1872198Sguido } else if (string_match(tok, string)) { /* ALL or exact match */ 1882198Sguido return (YES); 18922230Spst } else if ((group = getgrnam(tok)) != NULL) {/* try group membership */ 1902198Sguido for (i = 0; group->gr_mem[i]; i++) 1912198Sguido if (strcasecmp(string, group->gr_mem[i]) == 0) 1922198Sguido return (YES); 1932198Sguido } 1942198Sguido return (NO); 1952198Sguido} 1962198Sguido 1972198Sguido/* from_match - match a host or tty against a list of tokens */ 1982198Sguido 19990145Smarkmstatic int 20090145Smarkmfrom_match(const char *tok, const char *string) 2012198Sguido{ 2022198Sguido int tok_len; 2032198Sguido int str_len; 2042198Sguido 2052198Sguido /* 2062198Sguido * If a token has the magic value "ALL" the match always succeeds. Return 2072198Sguido * YES if the token fully matches the string. If the token is a domain 2082198Sguido * name, return YES if it matches the last fields of the string. If the 2092198Sguido * token has the magic value "LOCAL", return YES if the string does not 2102198Sguido * contain a "." character. If the token is a network number, return YES 2112198Sguido * if it matches the head of the string. 2122198Sguido */ 2132198Sguido 2142198Sguido if (tok[0] == '@') { /* netgroup */ 2152198Sguido return (netgroup_match(tok + 1, string, (char *) 0)); 2162198Sguido } else if (string_match(tok, string)) { /* ALL or exact match */ 2172198Sguido return (YES); 2182198Sguido } else if (tok[0] == '.') { /* domain: match last fields */ 2192198Sguido if ((str_len = strlen(string)) > (tok_len = strlen(tok)) 2202198Sguido && strcasecmp(tok, string + str_len - tok_len) == 0) 2212198Sguido return (YES); 2222198Sguido } else if (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */ 2232198Sguido if (strchr(string, '.') == 0) 2242198Sguido return (YES); 2252198Sguido } else if (tok[(tok_len = strlen(tok)) - 1] == '.' /* network */ 2262198Sguido && strncmp(tok, string, tok_len) == 0) { 2272198Sguido return (YES); 2282198Sguido } 2292198Sguido return (NO); 2302198Sguido} 2312198Sguido 2322198Sguido/* string_match - match a string against one token */ 2332198Sguido 23490145Smarkmstatic int 23590145Smarkmstring_match(const char *tok, const char *string) 2362198Sguido{ 2372198Sguido 2382198Sguido /* 2392198Sguido * If the token has the magic value "ALL" the match always succeeds. 2402198Sguido * Otherwise, return YES if the token fully matches the string. 2412198Sguido */ 2422198Sguido 2432198Sguido if (strcasecmp(tok, "ALL") == 0) { /* all: always matches */ 2442198Sguido return (YES); 2452198Sguido } else if (strcasecmp(tok, string) == 0) { /* try exact match */ 2462198Sguido return (YES); 2472198Sguido } 2482198Sguido return (NO); 2492198Sguido} 250