384 lines
9.2 KiB
C
384 lines
9.2 KiB
C
/*
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* Figure out if UNIX passwords are permitted for any combination of user
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* name, group member, terminal port, host_name or network:
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*
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* Programmatic interface: skeyaccess(char *user, char *port, char *host)
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*
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* Specify a null character pointer where information is not available.
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*
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* When compiled with -DPERMIT_CONSOLE always permits UNIX passwords with
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* console logins, no matter what the configuration file says.
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*
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* To build a stand-alone test version, compile with -DTEST and run it off an
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* skey.access file in the current directory:
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*
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* Command-line interface: ./skeyaccess user port [host]
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*
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* Author: Wietse Venema, Eindhoven University of Technology.
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <string.h>
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#include <netdb.h>
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#include <arpa/inet.h>
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#include <stdio.h>
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#include <grp.h>
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#include <ctype.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <sys/param.h>
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#include "pathnames.h"
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/*
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* Token input with one-deep pushback.
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*/
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static char *prev_token = 0; /* push-back buffer */
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static char *first_token();
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static int line_number;
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static void unget_token();
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static char *get_token();
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static char *need_token();
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static char *need_internet_addr();
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/*
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* Various forms of token matching.
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*/
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#define match_host_name(l) match_token((l)->host_name)
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#define match_port(l) match_token((l)->port)
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#define match_user(l) match_token((l)->user)
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static int match_internet_addr();
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static int match_group();
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static int match_token();
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static int is_internet_addr();
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#define MAX_ADDR 32
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#define PERMIT 1
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#define DENY 0
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struct login_info {
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char *host_name; /* host name */
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struct in_addr *internet_addr; /* null terminated list */
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char *user; /* user name */
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char *port; /* login port */
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};
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/* skeyaccess - find out if UNIX passwords are permitted */
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int skeyaccess(user, port, host)
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char *user;
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char *port;
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char *host;
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{
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struct hostent *hp;
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struct login_info login_info;
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struct in_addr internet_addr[MAX_ADDR + 1];
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char hostname_buf[MAXHOSTNAMELEN + 1];
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int i;
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login_info.user = user;
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login_info.port = port;
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login_info.host_name = 0;
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login_info.internet_addr = 0;
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if (host) {
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if (is_internet_addr(host)) { /* not DECnet */
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internet_addr[0].s_addr = inet_addr(host);
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internet_addr[1].s_addr = 0;
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login_info.internet_addr = internet_addr;
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} else {
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if ((hp = gethostbyname(host)) != 0 && hp->h_addrtype == AF_INET) {
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for (i = 0; i < MAX_ADDR && hp->h_addr_list[i]; i++)
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memcpy((char *) &internet_addr[i],
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hp->h_addr_list[i], hp->h_length);
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internet_addr[i].s_addr = 0;
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login_info.internet_addr = internet_addr;
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host = hp->h_name;
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}
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strncpy(hostname_buf, host, MAXHOSTNAMELEN);
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hostname_buf[MAXHOSTNAMELEN] = 0;
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login_info.host_name = hostname_buf;
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}
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}
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/*
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* Print what we think the user wants us to do.
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*/
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#ifdef TEST
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printf("port: %s\n", login_info.port);
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printf("user: %s\n", login_info.user);
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printf("host: %s\n", login_info.host_name ? login_info.host_name : "none");
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printf("addr: ");
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if (login_info.internet_addr == 0) {
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printf("none\n");
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} else {
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for (i = 0; login_info.internet_addr[i].s_addr; i++)
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printf("%s%s", inet_ntoa(login_info.internet_addr[i]),
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login_info.internet_addr[i + 1].s_addr ? " " : "\n");
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}
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#endif
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return (_skeyaccess(&login_info));
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}
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/* _skeyaccess - find out if UNIX passwords are permitted */
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int _skeyaccess(login_info)
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struct login_info *login_info;
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{
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FILE *fp;
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char buf[BUFSIZ];
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char *tok;
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int match;
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int permission;
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#ifdef PERMIT_CONSOLE
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if (login_info->port != 0 && strcasecmp(login_info->port, "console") == 0)
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return (1);
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#endif
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/*
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* Assume no restriction on the use of UNIX passwords when the s/key
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* acces table does not exist.
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*/
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if ((fp = fopen(_PATH_SKEYACCESS, "r")) == 0)
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return (PERMIT);
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/*
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* Scan the s/key access table until we find an entry that matches. If no
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* match is found, assume that UNIX passwords are disallowed.
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*/
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match = 0;
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while (match == 0 && (tok = first_token(buf, sizeof(buf), fp))) {
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if (strncasecmp(tok, "permit", 4) == 0) {
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permission = PERMIT;
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} else if (strncasecmp(tok, "deny", 4) == 0) {
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permission = DENY;
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} else {
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syslog(LOG_ERR, "%s: line %d: bad permission: %s",
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_PATH_SKEYACCESS, line_number, tok);
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continue; /* error */
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}
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/*
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* Process all conditions in this entry until we find one that fails.
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*/
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match = 1;
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while (match != 0 && (tok = get_token())) {
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if (strcasecmp(tok, "hostname") == 0) {
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match = match_host_name(login_info);
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} else if (strcasecmp(tok, "port") == 0) {
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match = match_port(login_info);
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} else if (strcasecmp(tok, "user") == 0) {
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match = match_user(login_info);
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} else if (strcasecmp(tok, "group") == 0) {
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match = match_group(login_info);
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} else if (strcasecmp(tok, "internet") == 0) {
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match = match_internet_addr(login_info);
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} else if (is_internet_addr(tok)) {
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unget_token(tok);
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match = match_internet_addr(login_info);
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} else {
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syslog(LOG_ERR, "%s: line %d: bad condition: %s",
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_PATH_SKEYACCESS, line_number, tok);
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match = 0;
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}
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}
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}
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fclose(fp);
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return (match ? permission : DENY);
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}
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/* match_internet_addr - match internet network address */
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static int match_internet_addr(login_info)
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struct login_info *login_info;
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{
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char *tok;
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long pattern;
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long mask;
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struct in_addr *addrp;
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struct hostent *hp;
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if (login_info->internet_addr == 0)
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return (0);
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if ((tok = need_internet_addr()) == 0)
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return (0);
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pattern = inet_addr(tok);
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if ((tok = need_internet_addr()) == 0)
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return (0);
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mask = inet_addr(tok);
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/*
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* See if any of the addresses matches a pattern in the control file.
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* Report and skip the address if it does not belong to the remote host.
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* Assume localhost == localhost.domain.
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*/
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#define NEQ(x,y) (strcasecmp((x),(y)) != 0)
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for (addrp = login_info->internet_addr; addrp->s_addr; addrp++) {
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if ((addrp->s_addr & mask) == pattern) {
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if (login_info->host_name != 0 &&
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((hp = gethostbyaddr((char *) addrp, sizeof(*addrp), AF_INET)) == 0
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|| (NEQ(login_info->host_name, hp->h_name)
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&& NEQ(login_info->host_name, "localhost")))) {
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syslog(LOG_ERR, "address %s not registered for host %s",
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inet_ntoa(*addrp), login_info->host_name);
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continue;
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}
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return (1);
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}
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}
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return (0);
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}
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/* match_group - match username against group */
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static int match_group(login_info)
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struct login_info *login_info;
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{
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struct group *group;
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char *tok;
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char **memp;
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if ((tok = need_token()) && (group = getgrnam(tok))) {
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for (memp = group->gr_mem; *memp; memp++)
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if (strcmp(login_info->user, *memp) == 0)
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return (1);
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}
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return (0); /* XXX endgrent() */
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}
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/* match_token - get and match token */
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static int match_token(str)
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char *str;
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{
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char *tok;
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return (str && (tok = need_token()) && strcasecmp(str, tok) == 0);
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}
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/* first_token - read line and return first token */
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static char *first_token(buf, len, fp)
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char *buf;
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int len;
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FILE *fp;
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{
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char *cp;
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prev_token = 0;
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for (;;) {
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if (fgets(buf, len, fp) == 0)
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return (0);
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line_number++;
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buf[strcspn(buf, "\r\n#")] = 0;
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#ifdef TEST
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if (buf[0])
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printf("rule: %s\n", buf);
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#endif
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if (cp = strtok(buf, " \t"))
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return (cp);
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}
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}
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/* unget_token - push back last token */
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static void unget_token(cp)
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char *cp;
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{
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prev_token = cp;
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}
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/* get_token - retrieve next token from buffer */
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static char *get_token()
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{
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char *cp;
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if (cp = prev_token) {
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prev_token = 0;
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} else {
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cp = strtok((char *) 0, " \t");
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}
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return (cp);
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}
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/* need_token - complain if next token is not available */
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static char *need_token()
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{
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char *cp;
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if ((cp = get_token()) == 0)
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syslog(LOG_ERR, "%s: line %d: premature end of rule",
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_PATH_SKEYACCESS, line_number);
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return (cp);
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}
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/* need_internet_addr - complain if next token is not an internet address */
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static char *need_internet_addr()
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{
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char *cp;
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if ((cp = get_token()) == 0) {
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syslog(LOG_ERR, "%s: line %d: internet address expected",
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_PATH_SKEYACCESS, line_number);
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return (0);
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} else if (!is_internet_addr(cp)) {
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syslog(LOG_ERR, "%s: line %d: bad internet address: %s",
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_PATH_SKEYACCESS, line_number, cp);
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return (0);
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} else {
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return (cp);
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}
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}
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/* is_internet_addr - determine if string is a dotted quad decimal address */
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static int is_internet_addr(str)
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char *str;
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{
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int in_run = 0;
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int runs = 0;
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/* Count the number of runs of characters between the dots. */
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while (*str) {
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if (*str == '.') {
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in_run = 0;
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} else {
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if (!isdigit(*str))
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return (0);
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if (in_run == 0) {
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in_run = 1;
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runs++;
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}
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}
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str++;
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}
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return (runs == 4);
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}
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#ifdef TEST
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main(argc, argv)
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int argc;
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char **argv;
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{
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if (argc != 3 && argc != 4) {
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fprintf(stderr, "usage: %s user port [host_or_ip_address]\n", argv[0]);
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exit(0);
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}
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openlog("login", LOG_PID, LOG_AUTH);
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printf("%s\n", skeyaccess(argv[1], argv[2], argv[3]) ? "YES" : "NO");
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return (0);
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}
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#endif
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