minix/lib/libminlib/servxcheck.c

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/* servxcheck() - Service access check. Author: Kees J. Bot
* 8 Jan 1997
*/
#define nil 0
#define ioctl _ioctl
#define open _open
#define write _write
#define close _close
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <sys/ioctl.h>
#include <net/hton.h>
#include <net/gen/in.h>
#include <net/gen/tcp.h>
#include <net/gen/tcp_io.h>
#include <net/gen/inet.h>
#include <net/gen/socket.h>
#include <net/gen/netdb.h>
/* Default service access file. */
static const char *path_servacces = _PATH_SERVACCES;
#define WLEN 256
static int getword(FILE *fp, char *word)
/* Read a word from the file open by 'fp', skip whitespace and comments.
* Colon and semicolon are returned as a one character "word". Returns
* word[0] or EOF.
*/
{
int c;
char *pw;
int wc;
wc= 0;
for (;;) {
if ((c= getc(fp)) == EOF) return EOF;
if (c == '#') { wc= 1; continue; }
if (c == '\n') { wc= 0; continue; }
if (wc) continue;
if (c <= ' ') continue;
break;
}
pw= word;
if (c == ':' || c == ';') {
*pw++ = c;
} else {
do {
if (pw < word + WLEN-1) *pw++ = c;
c= getc(fp);
} while (c != EOF && c > ' ' && c != ':' && c != ';');
if (c != EOF) ungetc(c, fp);
}
*pw= 0;
return word[0];
}
static int netspec(char *word, ipaddr_t *addr, ipaddr_t *mask)
/* Try to interpret 'word' as an network spec, e.g. 172.16.102.64/27. */
{
char *slash;
int r;
static char S32[]= "/32";
if (*word == 0) return 0;
if ((slash= strchr(word, '/')) == NULL) slash= S32;
*slash= 0;
r= inet_aton(word, addr);
*slash++= '/';
if (!r) return 0;
r= 0;
while ((*slash - '0') < 10u) {
r= 10*r + (*slash++ - '0');
if (r > 32) return 0;
}
if (*slash != 0 || slash[-1] == '/') return 0;
*mask= htonl(r == 0 ? 0L : (0xFFFFFFFFUL >> (32 - r)) << (32 - r));
return 1;
}
static int match(const char *word, const char *pattern)
/* Match word onto a pattern. Pattern may contain the * wildcard. */
{
unsigned cw, cp;
#define lc(c, d) ((((c)= (d)) - 'A') <= ('Z' - 'A') ? (c)+= ('a' - 'A') : 0)
for (;;) {
(void) lc(cw, *word);
(void) lc(cp, *pattern);
if (cp == '*') {
do pattern++; while (*pattern == '*');
(void) lc(cp, *pattern);
if (cp == 0) return 1;
while (cw != 0) {
if (cw == cp && match(word+1, pattern+1)) return 1;
word++;
(void) lc(cw, *word);
}
return 0;
} else
if (cw == 0 || cp == 0) {
return cw == cp;
} else
if (cw == cp) {
word++;
pattern++;
} else {
return 0;
}
}
#undef lc
}
static int get_name(ipaddr_t addr, char *name)
/* Do a reverse lookup on the remote IP address followed by a forward lookup
* to check if the host has that address. Return true if this is so, return
* either the true name or the ascii IP address in name[].
*/
{
struct hostent *he;
int i;
he= gethostbyaddr((char *) &addr, sizeof(addr), AF_INET);
if (he != NULL) {
strcpy(name, he->h_name);
he= gethostbyname(name);
if (he != NULL && he->h_addrtype == AF_INET) {
for (i= 0; he->h_addr_list[i] != NULL; i++) {
if (memcmp(he->h_addr_list[i], &addr, sizeof(addr)) == 0) {
strcpy(name, he->h_name);
return 1;
}
}
}
}
strcpy(name, inet_ntoa(addr));
return 0;
}
/* "state" and "log" flags, made to be bitwise comparable. */
#define DEFFAIL 0x01
#define FAIL (0x02 | DEFFAIL)
#define PASS 0x04
int servxcheck(unsigned long peer, const char *service,
void (*logf)(int pass, const char *name))
{
FILE *fp;
char word[WLEN];
char name[WLEN];
int c;
int got_name, slist, seen, explicit, state, log;
ipaddr_t addr, mask;
/* Localhost? */
if ((peer & htonl(0xFF000000)) == htonl(0x7F000000)) return 1;
if ((fp= fopen(path_servacces, "r")) == nil) {
/* Succeed on error, fail if simply nonexistent. */
return (errno != ENOENT);
}
slist= 1; /* Services list (before the colon.) */
seen= 0; /* Given service not yet seen. */
explicit= 0; /* Service mentioned explicitly. */
got_name= -1; /* No reverse lookup done yet. */
log= FAIL; /* By default log failures only. */
state= DEFFAIL; /* Access denied until we know better. */
while ((c= getword(fp, word)) != EOF) {
if (c == ':') {
slist= 0; /* Switch to access list. */
} else
if (c == ';') {
slist= 1; /* Back to list of services. */
seen= 0;
} else
if (slist) {
/* Traverse services list. */
if (match(service, word)) {
/* Service has been spotted! */
if (match(word, service)) {
/* Service mentioned without wildcards. */
seen= explicit= 1;
} else {
/* Matched by a wildcard. */
if (!explicit) seen= 1;
}
}
} else {
/* Traverse access list. */
if (c == 'l' && strcmp(word, "log") == 0) {
if (seen) {
/* Log failures and successes. */
log= FAIL|PASS;
}
continue;
}
if (c != '-' && c != '+') {
if (logf == nil) {
syslog(LOG_ERR, "%s: strange check word '%s'\n",
path_servacces, word);
}
continue;
}
if (seen) {
if (state == DEFFAIL) {
/* First check determines the default. */
state= c == '+' ? FAIL : PASS;
}
if ((state == PASS) == (c == '+')) {
/* This check won't change state. */
} else
if (word[1] == 0) {
/* Lone + or - allows all or none. */
state= c == '-' ? FAIL : PASS;
} else
if (netspec(word+1, &addr, &mask)) {
/* Remote host is on the specified network? */
if (((peer ^ addr) & mask) == 0) {
state= c == '-' ? FAIL : PASS;
}
} else {
/* Name check. */
if (got_name == -1) {
got_name= get_name(peer, name);
}
/* Remote host name matches the word? */
if (!got_name) {
state= FAIL;
} else
if (match(name, word+1)) {
state= c == '-' ? FAIL : PASS;
}
}
}
}
}
fclose(fp);
if ((log & state) != 0) {
/* Log the result of the check. */
if (got_name == -1) (void) get_name(peer, name);
if (logf != nil) {
(*logf)(state == PASS, name);
} else {
syslog(LOG_NOTICE, "service '%s' %s to %s\n",
service, state == PASS ? "granted" : "denied", name);
}
}
return state == PASS;
}
char *servxfile(const char *file)
/* Specify a file to use for the access checks other than the default. Return
* the old path.
*/
{
const char *oldpath= path_servacces;
path_servacces= file;
return (char *) oldpath; /* (avoid const poisoning) */
}