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freebsd/lib/libskey/skeyaccess.c
Hajimu UMEMOTO 015136259e IPv6 support for skeyaccess(3). You can specify IPv6 address
using `internet' keyword into /etc/skey.access.

Not Objected to by:	-audit and -net
2001-04-05 19:56:54 +00:00

589 lines
15 KiB
C

/*
* Figure out if UNIX passwords are permitted for any combination of user
* name, group member, terminal port, host_name or network:
*
* Programmatic interface: skeyaccess(user, port, host, addr)
*
* All arguments are null-terminated strings. Specify a null character pointer
* where information is not available.
*
* When no address information is given this code performs the host (internet)
* address lookup itself. It rejects addresses that appear to belong to
* someone else.
*
* When compiled with -DPERMIT_CONSOLE always permits UNIX passwords with
* console logins, no matter what the configuration file says.
*
* To build a stand-alone test version, compile with -DTEST and run it off an
* skey.access file in the current directory:
*
* Command-line interface: ./skeyaccess user port [host_or_ip_addr]
*
* Errors are reported via syslogd.
*
* Author: Wietse Venema, Eindhoven University of Technology.
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <grp.h>
#include <ctype.h>
#include <syslog.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/param.h>
#include "pathnames.h"
/*
* Token input with one-deep pushback.
*/
static char *prev_token = 0; /* push-back buffer */
static char *line_pointer = NULL;
static char *first_token __P((char *, int, FILE *));
static int line_number;
static void unget_token __P((char *));
static char *get_token __P((void));
static char *need_token __P((void));
static char *need_internet_addr __P((void));
/*
* Various forms of token matching.
*/
#define match_host_name(l) match_token((l)->host_name)
#define match_port(l) match_token((l)->port)
#define match_user(l) match_token((l)->user)
struct login_info;
static int match_internet_addr __P((struct login_info *));
static int match_group __P((struct login_info *));
static int match_token __P((char *));
static int is_internet_addr __P((char *));
static struct addrinfo *convert_internet_addr __P((char *));
static struct addrinfo *lookup_internet_addr __P((char *));
#define MAX_ADDR 32
#define PERMIT 1
#define DENY 0
#ifndef CONSOLE
#define CONSOLE "console"
#endif
#ifndef VTY_PREFIX
#define VTY_PREFIX "ttyv"
#endif
struct login_info {
char *host_name; /* host name */
struct addrinfo *internet_addr; /* addrinfo chain */
char *user; /* user name */
char *port; /* login port */
};
static int _skeyaccess __P((FILE *, struct login_info *));
int skeyaccess __P((char *, char *, char *, char *));
/* skeyaccess - find out if UNIX passwords are permitted */
int skeyaccess(user, port, host, addr)
char *user;
char *port;
char *host;
char *addr;
{
FILE *fp;
struct login_info login_info;
int result;
/*
* Assume no restriction on the use of UNIX passwords when the s/key
* acces table does not exist.
*/
if ((fp = fopen(_PATH_SKEYACCESS, "r")) == 0) {
#ifdef TEST
fprintf(stderr, "No file %s, thus no access control\n", _PATH_SKEYACCESS);
#endif
return (PERMIT);
}
/*
* Bundle up the arguments in a structure so we won't have to drag around
* boring long argument lists.
*
* Look up the host address when only the name is given. We try to reject
* addresses that belong to someone else.
*/
login_info.user = user;
login_info.port = port;
if (host != NULL && !is_internet_addr(host)) {
login_info.host_name = host;
} else {
login_info.host_name = NULL;
}
if (addr != NULL && is_internet_addr(addr)) {
login_info.internet_addr = convert_internet_addr(addr);
} else if (host != NULL) {
if (is_internet_addr(host)) {
login_info.internet_addr = convert_internet_addr(host);
} else {
login_info.internet_addr = lookup_internet_addr(host);
}
} else {
login_info.internet_addr = NULL;
}
/*
* Print what we think the user wants us to do.
*/
#ifdef TEST
printf("port: %s\n", login_info.port);
printf("user: %s\n", login_info.user);
printf("host: %s\n", login_info.host_name ? login_info.host_name : "none");
printf("addr: ");
if (login_info.internet_addr == NULL) {
printf("none\n");
} else {
struct addrinfo *res;
char haddr[NI_MAXHOST];
for (res = login_info.internet_addr; res; res = res->ai_next) {
getnameinfo(res->ai_addr, res->ai_addrlen, haddr, sizeof(haddr),
NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
printf("%s%s", haddr, res->ai_next ? " " : "\n");
}
}
#endif
result = _skeyaccess(fp, &login_info);
fclose(fp);
if (login_info.internet_addr)
freeaddrinfo(login_info.internet_addr);
return (result);
}
/* _skeyaccess - find out if UNIX passwords are permitted */
static int _skeyaccess(fp, login_info)
FILE *fp;
struct login_info *login_info;
{
char buf[BUFSIZ];
char *tok;
int match;
int permission=DENY;
#ifdef PERMIT_CONSOLE
if (login_info->port != 0 &&
(strcmp(login_info->port, CONSOLE) == 0 ||
strncmp(login_info->port, VTY_PREFIX, sizeof(VTY_PREFIX) - 1) == 0
)
)
return (1);
#endif
/*
* Scan the s/key access table until we find an entry that matches. If no
* match is found, assume that UNIX passwords are disallowed.
*/
match = 0;
while (match == 0 && (tok = first_token(buf, sizeof(buf), fp))) {
if (strncasecmp(tok, "permit", 4) == 0) {
permission = PERMIT;
} else if (strncasecmp(tok, "deny", 4) == 0) {
permission = DENY;
} else {
syslog(LOG_ERR, "%s: line %d: bad permission: %s",
_PATH_SKEYACCESS, line_number, tok);
continue; /* error */
}
/*
* Process all conditions in this entry until we find one that fails.
*/
match = 1;
while (match != 0 && (tok = get_token())) {
if (strcasecmp(tok, "hostname") == 0) {
match = match_host_name(login_info);
} else if (strcasecmp(tok, "port") == 0) {
match = match_port(login_info);
} else if (strcasecmp(tok, "user") == 0) {
match = match_user(login_info);
} else if (strcasecmp(tok, "group") == 0) {
match = match_group(login_info);
} else if (strcasecmp(tok, "internet") == 0) {
match = match_internet_addr(login_info);
} else if (is_internet_addr(tok)) {
unget_token(tok);
match = match_internet_addr(login_info);
} else {
syslog(LOG_ERR, "%s: line %d: bad condition: %s",
_PATH_SKEYACCESS, line_number, tok);
match = 0;
}
}
}
return (match ? permission : DENY);
}
/* translate IPv4 mapped IPv6 address to IPv4 address */
static void
ai_unmapped(struct addrinfo *ai)
{
struct sockaddr_in6 *sin6;
struct sockaddr_in *sin4;
u_int32_t addr;
int port;
if (ai->ai_family != AF_INET6)
return;
sin6 = (struct sockaddr_in6 *)ai->ai_addr;
if (!IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
return;
sin4 = (struct sockaddr_in *)ai->ai_addr;
addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12];
port = sin6->sin6_port;
memset(sin4, 0, sizeof(struct sockaddr_in));
sin4->sin_addr.s_addr = addr;
sin4->sin_port = port;
sin4->sin_family = AF_INET;
sin4->sin_len = sizeof(struct sockaddr_in);
ai->ai_family = AF_INET;
ai->ai_addrlen = sizeof(struct sockaddr_in);
}
/* match_internet_addr - match internet network address */
static int match_internet_addr(login_info)
struct login_info *login_info;
{
char *tok;
struct addrinfo *res;
struct sockaddr_storage pattern, mask;
struct sockaddr_in *addr4, *pattern4, *mask4;
struct sockaddr_in6 *addr6, *pattern6, *mask6;
int i, match;
if (login_info->internet_addr == NULL)
return (0);
if ((tok = need_internet_addr()) == 0)
return (0);
if ((res = convert_internet_addr(tok)) == NULL)
return (0);
memcpy(&pattern, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);
if ((tok = need_internet_addr()) == 0)
return (0);
if ((res = convert_internet_addr(tok)) == NULL)
return (0);
memcpy(&mask, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);
if (pattern.ss_family != mask.ss_family)
return (0);
mask4 = (struct sockaddr_in *)&mask;
pattern4 = (struct sockaddr_in *)&pattern;
mask6 = (struct sockaddr_in6 *)&mask;
pattern6 = (struct sockaddr_in6 *)&pattern;
/*
* See if any of the addresses matches a pattern in the control file. We
* have already tried to drop addresses that belong to someone else.
*/
for (res = login_info->internet_addr; res; res = res->ai_next) {
ai_unmapped(res);
if (res->ai_family != pattern.ss_family)
continue;
switch (res->ai_family) {
case AF_INET:
addr4 = (struct sockaddr_in *)res->ai_addr;
if (addr4->sin_addr.s_addr != INADDR_NONE &&
(addr4->sin_addr.s_addr & mask4->sin_addr.s_addr) == pattern4->sin_addr.s_addr)
return (1);
break;
case AF_INET6:
addr6 = (struct sockaddr_in6 *)res->ai_addr;
if (pattern6->sin6_scope_id != 0 &&
addr6->sin6_scope_id != pattern6->sin6_scope_id)
break;
match = 1;
for (i = 0; i < 16; ++i) {
if ((addr6->sin6_addr.s6_addr[i] & mask6->sin6_addr.s6_addr[i]) != pattern6->sin6_addr.s6_addr[i]) {
match = 0;
break;
}
}
if (match)
return (1);
break;
}
}
return (0);
}
/* match_group - match username against group */
static int match_group(login_info)
struct login_info *login_info;
{
struct group *group;
char *tok;
char **memp;
if ((tok = need_token()) && (group = getgrnam(tok))) {
for (memp = group->gr_mem; *memp; memp++)
if (strcmp(login_info->user, *memp) == 0)
return (1);
}
return (0); /* XXX endgrent() */
}
/* match_token - get and match token */
static int match_token(str)
char *str;
{
char *tok;
return (str && (tok = need_token()) && strcasecmp(str, tok) == 0);
}
/* first_token - read line and return first token */
static char *first_token(buf, len, fp)
char *buf;
int len;
FILE *fp;
{
char *cp;
prev_token = 0;
for (;;) {
if (fgets(buf, len, fp) == 0)
return (0);
line_number++;
buf[strcspn(buf, "\r\n#")] = 0;
#ifdef TEST
if (buf[0])
printf("rule: %s\n", buf);
#endif
line_pointer = buf;
while ((cp = strsep(&line_pointer, " \t")) != NULL && *cp == '\0')
;
if (cp != NULL)
return (cp);
}
}
/* unget_token - push back last token */
static void unget_token(cp)
char *cp;
{
prev_token = cp;
}
/* get_token - retrieve next token from buffer */
static char *get_token()
{
char *cp;
if ( (cp = prev_token) ) {
prev_token = 0;
} else {
while ((cp = strsep(&line_pointer, " \t")) != NULL && *cp == '\0')
;
}
return (cp);
}
/* need_token - complain if next token is not available */
static char *need_token()
{
char *cp;
if ((cp = get_token()) == 0)
syslog(LOG_ERR, "%s: line %d: premature end of rule",
_PATH_SKEYACCESS, line_number);
return (cp);
}
/* need_internet_addr - complain if next token is not an internet address */
static char *need_internet_addr()
{
char *cp;
if ((cp = get_token()) == 0) {
syslog(LOG_ERR, "%s: line %d: internet address expected",
_PATH_SKEYACCESS, line_number);
return (0);
} else if (!is_internet_addr(cp)) {
syslog(LOG_ERR, "%s: line %d: bad internet address: %s",
_PATH_SKEYACCESS, line_number, cp);
return (0);
} else {
return (cp);
}
}
/* is_internet_addr - determine if string is a dotted quad decimal address */
static int is_internet_addr(str)
char *str;
{
struct addrinfo *res;
if ((res = convert_internet_addr(str)) != NULL)
freeaddrinfo(res);
return (res != NULL);
}
/*
* Nuke addrinfo entry from list.
* XXX: Depending on the implementation of KAME's getaddrinfo(3).
*/
static void nuke_ai(aip)
struct addrinfo **aip;
{
struct addrinfo *ai;
ai = *aip;
*aip = ai->ai_next;
if (ai->ai_canonname) {
if (ai->ai_next && !ai->ai_next->ai_canonname)
ai->ai_next->ai_canonname = ai->ai_canonname;
else
free(ai->ai_canonname);
}
free(ai);
}
/* lookup_internet_addr - look up internet addresses with extreme prejudice */
static struct addrinfo *lookup_internet_addr(host)
char *host;
{
struct addrinfo hints, *res0, *res, **resp;
char hname[NI_MAXHOST], haddr[NI_MAXHOST];
int error;
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE | AI_CANONNAME;
if (getaddrinfo(host, NULL, &hints, &res0) != 0)
return (NULL);
if (res0->ai_canonname == NULL) {
freeaddrinfo(res0);
return (NULL);
}
/*
* Wipe addresses that appear to belong to someone else. We will get
* false alarms when when the hostname comes from DNS, while its
* addresses are listed under different names in local databases.
*/
#define NEQ(x,y) (strcasecmp((x),(y)) != 0)
#define NEQ3(x,y,n) (strncasecmp((x),(y), (n)) != 0)
resp = &res0;
while ((res = *resp) != NULL) {
if (res->ai_family != AF_INET && res->ai_family != AF_INET6) {
nuke_ai(resp);
continue;
}
error = getnameinfo(res->ai_addr, res->ai_addrlen,
hname, sizeof(hname),
NULL, 0, NI_NAMEREQD | NI_WITHSCOPEID);
if (error) {
getnameinfo(res->ai_addr, res->ai_addrlen, haddr, sizeof(haddr),
NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
syslog(LOG_ERR, "address %s not registered for host %s",
haddr, res0->ai_canonname);
nuke_ai(resp);
continue;
}
if (NEQ(res0->ai_canonname, hname) &&
NEQ3(res0->ai_canonname, "localhost.", 10)) {
getnameinfo(res->ai_addr, res->ai_addrlen, haddr, sizeof(haddr),
NULL, 0, NI_NUMERICHOST | NI_WITHSCOPEID);
syslog(LOG_ERR, "address %s registered for host %s and %s",
haddr, hname, res0->ai_canonname);
nuke_ai(resp);
continue;
}
resp = &res->ai_next;
}
return (res0);
}
/* convert_internet_addr - convert string to internet address */
static struct addrinfo *convert_internet_addr(string)
char *string;
{
struct addrinfo hints, *res;
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
if (getaddrinfo(string, NULL, &hints, &res) != 0)
return (NULL);
return (res);
}
#ifdef TEST
main(argc, argv)
int argc;
char **argv;
{
struct addrinfo hints, *res;
char host[MAXHOSTNAMELEN + 1];
int verdict;
char *user;
char *port;
if (argc != 3 && argc != 4) {
fprintf(stderr, "usage: %s user port [host_or_ip_address]\n", argv[0]);
exit(0);
}
if (_PATH_SKEYACCESS[0] != '/')
printf("Warning: this program uses control file: %s\n", _PATH_SKEYACCESS);
openlog("login", LOG_PID, LOG_AUTH);
user = argv[1];
port = argv[2];
if (argv[3]) {
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE | AI_CANONNAME;
if (getaddrinfo(argv[3], NULL, &hints, &res) == 0) {
if (res->ai_canonname == NULL)
strncpy(host, argv[3], MAXHOSTNAMELEN);
else
strncpy(host, res->ai_canonname, MAXHOSTNAMELEN);
freeaddrinfo(res);
} else
strncpy(host, argv[3], MAXHOSTNAMELEN);
host[MAXHOSTNAMELEN] = 0;
}
verdict = skeyaccess(user, port, argv[3] ? host : (char *) 0, (char *) 0);
printf("UNIX passwords %spermitted\n", verdict ? "" : "NOT ");
return (0);
}
#endif