/* pam_access module */
/*
* Written by Alexei Nogin <alexei@nogin.dnttm.ru> 1997/06/15
* (I took login_access from logdaemon-5.6 and converted it to PAM
* using parts of pam_time code.)
*
************************************************************************
* Copyright message from logdaemon-5.6 (original file name DISCLAIMER)
************************************************************************
* Copyright 1995 by Wietse Venema. All rights reserved. Individual files
* may be covered by other copyrights (as noted in the file itself.)
*
* This material was originally written and compiled by Wietse Venema at
* Eindhoven University of Technology, The Netherlands, in 1990, 1991,
* 1992, 1993, 1994 and 1995.
*
* Redistribution and use in source and binary forms are permitted
* provided that this entire copyright notice is duplicated in all such
* copies.
*
* This software is provided "as is" and without any expressed or implied
* warranties, including, without limitation, the implied warranties of
* merchantibility and fitness for any particular purpose.
*************************************************************************
*/
#include <security/_pam_aconf.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdarg.h>
#include <syslog.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <ctype.h>
#include <sys/utsname.h>
#ifndef BROKEN_NETWORK_MATCH
# include <netdb.h>
# include <sys/socket.h>
#endif
/*
* here, we make definitions for the externally accessible functions
* in this file (these definitions are required for static modules
* but strongly encouraged generally) they are used to instruct the
* modules include file to define their prototypes.
*/
#define PAM_SM_ACCOUNT
#include <security/_pam_macros.h>
#include <security/pam_modules.h>
int strcasecmp(const char *s1, const char *s2);
/* login_access.c from logdaemon-5.6 with several changes by A.Nogin: */
/*
* 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 !defined(MAXHOSTNAMELEN) || (MAXHOSTNAMELEN < 64)
#undef MAXHOSTNAMELEN
#define MAXHOSTNAMELEN 256
#endif
#ifdef DEFAULT_CONF_FILE
# define PAM_ACCESS_CONFIG DEFAULT_CONF_FILE
#else
# define PAM_ACCESS_CONFIG "/etc/security/access.conf"
#endif
/* Delimiters for fields and for lists of users, ttys or hosts. */
static const char *fs = ":"; /* field separator */
static const char sep[] = ", \t"; /* list-element separator */
/* Constants to be used in assignments only, not in comparisons... */
#define YES 1
#define NO 0
/*
* A structure to bundle up all login-related information to keep the
* functional interfaces as generic as possible.
*/
struct login_info {
struct passwd *user;
char *from;
const char *config_file;
const char *service;
};
/* --- static functions for checking whether the user should be let in --- */
static void _log_err(const char *format, ... )
{
va_list args;
va_start(args, format);
openlog("pam_access", LOG_CONS|LOG_PID, LOG_AUTH);
vsyslog(LOG_ERR, format, args);
va_end(args);
closelog();
}
/* Parse module config arguments */
static int parse_args(struct login_info *loginfo, int argc, const char **argv)
{
int i;
for (i=0; i<argc; ++i) {
if (!strncmp("fieldsep=", argv[i], 9)) {
/* the admin wants to override the default field separators */
fs = argv[i]+9;
} else if (!strncmp("accessfile=", argv[i], 11)) {
FILE *fp = fopen(11 + argv[i], "r");
if (fp) {
loginfo->config_file = 11 + argv[i];
fclose(fp);
} else {
_log_err("for service [%s] failed to open accessfile=[%s]"
, loginfo->service, 11 + argv[i]);
return 0;
}
} else {
_log_err("unrecognized option [%s]", argv[i]);
}
}
return 1; /* OK */
}
typedef int match_func (char *, struct login_info *);
static int list_match (char *, struct login_info *,
match_func *);
static int user_match (char *, struct login_info *);
static int from_match (char *, struct login_info *);
static int string_match (char *, char *);
/* login_access - match username/group and host/tty with access control file */
static int login_access(struct login_info *item)
{
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(item->config_file, "r"))!=NULL) {
while (!match && fgets(line, sizeof(line), fp)) {
lineno++;
if (line[end = strlen(line) - 1] != '\n') {
_log_err("%s: line %d: missing newline or line too long",
item->config_file, 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)) {
_log_err("%s: line %d: bad field count",
item->config_file, lineno);
continue;
}
if (perm[0] != '+' && perm[0] != '-') {
_log_err("%s: line %d: bad first field",
item->config_file, lineno);
continue;
}
match = (list_match(froms, item, from_match)
&& list_match(users, item, user_match));
}
(void) fclose(fp);
} else if (errno != ENOENT) {
_log_err("cannot open %s: %m", item->config_file);
}
return (match == 0 || (line[0] == '+'));
}
/* list_match - match an item against a list of tokens with exceptions */
static int list_match(char *list, struct login_info *item, match_func *match_fn)
{
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 != 0; tok = strtok((char *) 0, sep)) {
if (strcasecmp(tok, "EXCEPT") == 0) /* EXCEPT: give up */
break;
if ((match = (*match_fn) (tok, item))) /* YES */
break;
}
/* Process exceptions to matches. */
if (match != NO) {
while ((tok = strtok((char *) 0, sep)) && strcasecmp(tok, "EXCEPT"))
/* VOID */ ;
if (tok == 0 || list_match((char *) 0, item, match_fn) == NO)
return (match);
}
return (NO);
}
/* myhostname - figure out local machine name */
static char * myhostname(void)
{
static char name[MAXHOSTNAMELEN + 1];
gethostname(name, MAXHOSTNAMELEN);
name[MAXHOSTNAMELEN] = 0;
return (name);
}
/* netgroup_match - match group against machine or user */
static int netgroup_match(char *group, char *machine, char *user)
{
#ifdef NIS
static char *mydomain = 0;
if (mydomain == 0)
yp_get_default_domain(&mydomain);
return (innetgr(group, machine, user, mydomain));
#else
_log_err("NIS netgroup support not configured");
return (NO);
#endif
}
/* user_match - match a username against one token */
static int user_match(char *tok, struct login_info *item)
{
char *string = item->user->pw_name;
struct login_info fake_item;
struct group *group;
int i;
char *at;
/*
* If a token has the magic value "ALL" the match always succeeds.
* Otherwise, return YES if the token fully matches the username, if the
* token is a group that contains the username, or if the token is the
* name of the user's primary group.
*/
if ((at = strchr(tok + 1, '@')) != 0) { /* split user@host pattern */
*at = 0;
fake_item.from = myhostname();
return (user_match(tok, item) && from_match(at + 1, &fake_item));
} else 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 ((group = getgrnam(tok))) { /* try group membership */
if (item->user->pw_gid == group->gr_gid)
return (YES);
for (i = 0; group->gr_mem[i]; i++)
if (strcasecmp(string, group->gr_mem[i]) == 0)
return (YES);
}
return (NO);
}
/* from_match - match a host or tty against a list of tokens */
static int from_match(char *tok, struct login_info *item)
{
char *string = item->from;
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 (strcasecmp(tok, "LOCAL") == 0) { /* local: no dots */
if (strchr(string, '.') == 0)
return (YES);
#ifdef BROKEN_NETWORK_MATCH
} else if (tok[(tok_len = strlen(tok)) - 1] == '.' /* network */
&& strncmp(tok, string, tok_len) == 0) {
return (YES);
#else /* BROKEN_NETWORK_MATCH */
} else if (tok[(tok_len = strlen(tok)) - 1] == '.') {
/*
The code below does a more correct check if the address specified
by "string" starts from "tok".
1998/01/27 Andrey V. Savochkin <saw@msu.ru>
*/
struct hostent *h;
char hn[3+1+3+1+3+1+3+1+1];
int r;
h = gethostbyname(string);
if (h == NULL)
return (NO);
if (h->h_addrtype != AF_INET)
return (NO);
if (h->h_length != 4)
return (NO); /* only IPv4 addresses (SAW) */
r = snprintf(hn, sizeof(hn), "%u.%u.%u.%u.",
(unsigned char)h->h_addr[0], (unsigned char)h->h_addr[1],
(unsigned char)h->h_addr[2], (unsigned char)h->h_addr[3]);
if (r < 0 || r >= sizeof(hn))
return (NO);
if (!strncmp(tok, hn, tok_len))
return (YES);
#endif /* BROKEN_NETWORK_MATCH */
}
return (NO);
}
/* string_match - match a string against one token */
static int string_match(char *tok, 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 (strcasecmp(tok, "ALL") == 0) { /* all: always matches */
return (YES);
} else if (strcasecmp(tok, string) == 0) { /* try exact match */
return (YES);
}
return (NO);
}
/* end of login_access.c */
int strcasecmp(const char *s1, const char *s2)
{
while ((toupper(*s1)==toupper(*s2)) && (*s1) && (*s2)) {s1++; s2++;}
return(toupper(*s1)-toupper(*s2));
}
/* --- public account management functions --- */
PAM_EXTERN int pam_sm_acct_mgmt(pam_handle_t *pamh,int flags,int argc
,const char **argv)
{
struct login_info loginfo;
const char *user=NULL, *service=NULL;
char *from=NULL;
struct passwd *user_pw;
if ((pam_get_item(pamh, PAM_SERVICE, (const void **)&service)
!= PAM_SUCCESS) || (service == NULL) || (*service == ' ')) {
_log_err("cannot find the service name");
return PAM_ABORT;
}
/* set username */
if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS || user == NULL
|| *user == '\0') {
_log_err("cannot determine the user's name");
return PAM_USER_UNKNOWN;
}
/* remote host name */
if (pam_get_item(pamh, PAM_RHOST, (const void **)&from)
!= PAM_SUCCESS) {
_log_err("cannot find the remote host name");
return PAM_ABORT;
}
if ((from==NULL) || (*from=='\0')) {
/* local login, set tty name */
if (pam_get_item(pamh, PAM_TTY, (const void **)&from) != PAM_SUCCESS
|| from == NULL) {
D(("PAM_TTY not set, probing stdin"));
from = ttyname(STDIN_FILENO);
if (from == NULL) {
_log_err("couldn't get the tty name");
return PAM_ABORT;
}
if (pam_set_item(pamh, PAM_TTY, from) != PAM_SUCCESS) {
_log_err("couldn't set tty name");
return PAM_ABORT;
}
}
if (strncmp("/dev/",from,5) == 0) { /* strip leading /dev/ */
from += 5;
}
}
if ((user_pw=getpwnam(user))==NULL) return (PAM_USER_UNKNOWN);
/*
* Bundle up the arguments to avoid unnecessary clumsiness later on.
*/
loginfo.user = user_pw;
loginfo.from = from;
loginfo.service = service;
loginfo.config_file = PAM_ACCESS_CONFIG;
/* parse the argument list */
if (!parse_args(&loginfo, argc, argv)) {
_log_err("failed to parse the module arguments");
return PAM_ABORT;
}
if (login_access(&loginfo)) {
return (PAM_SUCCESS);
} else {
_log_err("access denied for user `%s' from `%s'",user,from);
return (PAM_PERM_DENIED);
}
}
/* end of module definition */
#ifdef PAM_STATIC
/* static module data */
struct pam_module _pam_access_modstruct = {
"pam_access",
NULL,
NULL,
pam_sm_acct_mgmt,
NULL,
NULL,
NULL
};
#endif