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openssh/ssh-keyscan.c

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/*
* Copyright 1995, 1996 by David Mazieres <dm@lcs.mit.edu>.
*
* Modification and redistribution in source and binary forms is
* permitted provided that due credit is given to the author and the
* OpenBSD project by leaving this copyright notice intact.
*/
#include "includes.h"
RCSID("$OpenBSD: ssh-keyscan.c,v 1.29 2001/08/30 22:22:32 markus Exp $");
#if defined(HAVE_SYS_QUEUE_H) && !defined(HAVE_BOGUS_SYS_QUEUE_H)
#include <sys/queue.h>
#else
#include "openbsd-compat/fake-queue.h"
#endif
#include <errno.h>
#include <openssl/bn.h>
#include <setjmp.h>
#include "xmalloc.h"
#include "ssh.h"
#include "ssh1.h"
#include "key.h"
#include "kex.h"
#include "compat.h"
#include "myproposal.h"
#include "packet.h"
#include "dispatch.h"
#include "buffer.h"
#include "bufaux.h"
#include "log.h"
#include "atomicio.h"
#include "misc.h"
/* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
Default value is AF_UNSPEC means both IPv4 and IPv6. */
#ifdef IPV4_DEFAULT
int IPv4or6 = AF_INET;
#else
int IPv4or6 = AF_UNSPEC;
#endif
int ssh_port = SSH_DEFAULT_PORT;
#define KT_RSA1 1
#define KT_DSA 2
#define KT_RSA 4
int get_keytypes = KT_RSA1; /* Get only RSA1 keys by default */
#define MAXMAXFD 256
/* The number of seconds after which to give up on a TCP connection */
int timeout = 5;
int maxfd;
#define MAXCON (maxfd - 10)
#ifdef HAVE___PROGNAME
extern char *__progname;
#else
char *__progname;
#endif
fd_set *read_wait;
size_t read_wait_size;
int ncon;
int nonfatal_fatal = 0;
jmp_buf kexjmp;
Key *kexjmp_key;
/*
* Keep a connection structure for each file descriptor. The state
* associated with file descriptor n is held in fdcon[n].
*/
typedef struct Connection {
u_char c_status; /* State of connection on this file desc. */
#define CS_UNUSED 0 /* File descriptor unused */
#define CS_CON 1 /* Waiting to connect/read greeting */
#define CS_SIZE 2 /* Waiting to read initial packet size */
#define CS_KEYS 3 /* Waiting to read public key packet */
int c_fd; /* Quick lookup: c->c_fd == c - fdcon */
int c_plen; /* Packet length field for ssh packet */
int c_len; /* Total bytes which must be read. */
int c_off; /* Length of data read so far. */
int c_keytype; /* Only one of KT_RSA1, KT_DSA, or KT_RSA */
char *c_namebase; /* Address to free for c_name and c_namelist */
char *c_name; /* Hostname of connection for errors */
char *c_namelist; /* Pointer to other possible addresses */
char *c_output_name; /* Hostname of connection for output */
char *c_data; /* Data read from this fd */
Kex *c_kex; /* The key-exchange struct for ssh2 */
struct timeval c_tv; /* Time at which connection gets aborted */
TAILQ_ENTRY(Connection) c_link; /* List of connections in timeout order. */
} con;
TAILQ_HEAD(conlist, Connection) tq; /* Timeout Queue */
con *fdcon;
/*
* This is just a wrapper around fgets() to make it usable.
*/
/* Stress-test. Increase this later. */
#define LINEBUF_SIZE 16
typedef struct {
char *buf;
u_int size;
int lineno;
const char *filename;
FILE *stream;
void (*errfun) (const char *,...);
} Linebuf;
static Linebuf *
Linebuf_alloc(const char *filename, void (*errfun) (const char *,...))
{
Linebuf *lb;
if (!(lb = malloc(sizeof(*lb)))) {
if (errfun)
(*errfun) ("linebuf (%s): malloc failed\n", lb->filename);
return (NULL);
}
if (filename) {
lb->filename = filename;
if (!(lb->stream = fopen(filename, "r"))) {
xfree(lb);
if (errfun)
(*errfun) ("%s: %s\n", filename, strerror(errno));
return (NULL);
}
} else {
lb->filename = "(stdin)";
lb->stream = stdin;
}
if (!(lb->buf = malloc(lb->size = LINEBUF_SIZE))) {
if (errfun)
(*errfun) ("linebuf (%s): malloc failed\n", lb->filename);
xfree(lb);
return (NULL);
}
lb->errfun = errfun;
lb->lineno = 0;
return (lb);
}
static void
Linebuf_free(Linebuf * lb)
{
fclose(lb->stream);
xfree(lb->buf);
xfree(lb);
}
#if 0
static void
Linebuf_restart(Linebuf * lb)
{
clearerr(lb->stream);
rewind(lb->stream);
lb->lineno = 0;
}
static int
Linebuf_lineno(Linebuf * lb)
{
return (lb->lineno);
}
#endif
static char *
Linebuf_getline(Linebuf * lb)
{
int n = 0;
lb->lineno++;
for (;;) {
/* Read a line */
if (!fgets(&lb->buf[n], lb->size - n, lb->stream)) {
if (ferror(lb->stream) && lb->errfun)
(*lb->errfun) ("%s: %s\n", lb->filename,
strerror(errno));
return (NULL);
}
n = strlen(lb->buf);
/* Return it or an error if it fits */
if (n > 0 && lb->buf[n - 1] == '\n') {
lb->buf[n - 1] = '\0';
return (lb->buf);
}
if (n != lb->size - 1) {
if (lb->errfun)
(*lb->errfun) ("%s: skipping incomplete last line\n",
lb->filename);
return (NULL);
}
/* Double the buffer if we need more space */
if (!(lb->buf = realloc(lb->buf, (lb->size *= 2)))) {
if (lb->errfun)
(*lb->errfun) ("linebuf (%s): realloc failed\n",
lb->filename);
return (NULL);
}
}
}
static int
fdlim_get(int hard)
{
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
struct rlimit rlfd;
if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
return (-1);
if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
return 10000;
else
return hard ? rlfd.rlim_max : rlfd.rlim_cur;
#elif defined (HAVE_SYSCONF)
return sysconf (_SC_OPEN_MAX);
#else
return 10000;
#endif
}
static int
fdlim_set(int lim)
{
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
struct rlimit rlfd;
#endif
if (lim <= 0)
return (-1);
#if defined(HAVE_SETRLIMIT) && defined(RLIMIT_NOFILE)
if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
return (-1);
rlfd.rlim_cur = lim;
if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
return (-1);
#elif defined (HAVE_SETDTABLESIZE)
setdtablesize(lim);
#endif
return (0);
}
/*
* This is an strsep function that returns a null field for adjacent
* separators. This is the same as the 4.4BSD strsep, but different from the
* one in the GNU libc.
*/
static char *
xstrsep(char **str, const char *delim)
{
char *s, *e;
if (!**str)
return (NULL);
s = *str;
e = s + strcspn(s, delim);
if (*e != '\0')
*e++ = '\0';
*str = e;
return (s);
}
/*
* Get the next non-null token (like GNU strsep). Strsep() will return a
* null token for two adjacent separators, so we may have to loop.
*/
static char *
strnnsep(char **stringp, char *delim)
{
char *tok;
do {
tok = xstrsep(stringp, delim);
} while (tok && *tok == '\0');
return (tok);
}
static Key *
keygrab_ssh1(con *c)
{
static Key *rsa;
static Buffer msg;
if (rsa == NULL) {
buffer_init(&msg);
rsa = key_new(KEY_RSA1);
}
buffer_append(&msg, c->c_data, c->c_plen);
buffer_consume(&msg, 8 - (c->c_plen & 7)); /* padding */
if (buffer_get_char(&msg) != (int) SSH_SMSG_PUBLIC_KEY) {
error("%s: invalid packet type", c->c_name);
buffer_clear(&msg);
return NULL;
}
buffer_consume(&msg, 8); /* cookie */
/* server key */
(void) buffer_get_int(&msg);
buffer_get_bignum(&msg, rsa->rsa->e);
buffer_get_bignum(&msg, rsa->rsa->n);
/* host key */
(void) buffer_get_int(&msg);
buffer_get_bignum(&msg, rsa->rsa->e);
buffer_get_bignum(&msg, rsa->rsa->n);
buffer_clear(&msg);
return (rsa);
}
static int
hostjump(Key *hostkey)
{
kexjmp_key = hostkey;
longjmp(kexjmp, 1);
}
static int
ssh2_capable(int remote_major, int remote_minor)
{
switch (remote_major) {
case 1:
if (remote_minor == 99)
return 1;
break;
case 2:
return 1;
default:
break;
}
return 0;
}
static Key *
keygrab_ssh2(con *c)
{
int j;
packet_set_connection(c->c_fd, c->c_fd);
enable_compat20();
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = c->c_keytype == KT_DSA?
"ssh-dss": "ssh-rsa";
c->c_kex = kex_setup(myproposal);
c->c_kex->verify_host_key = hostjump;
if (!(j = setjmp(kexjmp))) {
nonfatal_fatal = 1;
dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex);
fprintf(stderr, "Impossible! dispatch_run() returned!\n");
exit(1);
}
nonfatal_fatal = 0;
xfree(c->c_kex);
c->c_kex = NULL;
packet_close();
return j < 0? NULL : kexjmp_key;
}
static void
keyprint(con *c, Key *key)
{
if (!key)
return;
fprintf(stdout, "%s ", c->c_output_name ? c->c_output_name : c->c_name);
key_write(key, stdout);
fputs("\n", stdout);
}
static int
tcpconnect(char *host)
{
struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV];
int gaierr, s = -1;
snprintf(strport, sizeof strport, "%d", ssh_port);
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
fatal("getaddrinfo %s: %s", host, gai_strerror(gaierr));
for (ai = aitop; ai; ai = ai->ai_next) {
s = socket(ai->ai_family, SOCK_STREAM, 0);
if (s < 0) {
error("socket: %s", strerror(errno));
continue;
}
if (fcntl(s, F_SETFL, O_NONBLOCK) < 0)
fatal("F_SETFL: %s", strerror(errno));
if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0 &&
errno != EINPROGRESS)
error("connect (`%s'): %s", host, strerror(errno));
else
break;
close(s);
s = -1;
}
freeaddrinfo(aitop);
return s;
}
static int
conalloc(char *iname, char *oname, int keytype)
{
int s;
char *namebase, *name, *namelist;
namebase = namelist = xstrdup(iname);
do {
name = xstrsep(&namelist, ",");
if (!name) {
xfree(namebase);
return (-1);
}
} while ((s = tcpconnect(name)) < 0);
if (s >= maxfd)
fatal("conalloc: fdno %d too high", s);
if (fdcon[s].c_status)
fatal("conalloc: attempt to reuse fdno %d", s);
fdcon[s].c_fd = s;
fdcon[s].c_status = CS_CON;
fdcon[s].c_namebase = namebase;
fdcon[s].c_name = name;
fdcon[s].c_namelist = namelist;
fdcon[s].c_output_name = xstrdup(oname);
fdcon[s].c_data = (char *) &fdcon[s].c_plen;
fdcon[s].c_len = 4;
fdcon[s].c_off = 0;
fdcon[s].c_keytype = keytype;
gettimeofday(&fdcon[s].c_tv, NULL);
fdcon[s].c_tv.tv_sec += timeout;
TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
FD_SET(s, read_wait);
ncon++;
return (s);
}
static void
confree(int s)
{
if (s >= maxfd || fdcon[s].c_status == CS_UNUSED)
fatal("confree: attempt to free bad fdno %d", s);
close(s);
xfree(fdcon[s].c_namebase);
xfree(fdcon[s].c_output_name);
if (fdcon[s].c_status == CS_KEYS)
xfree(fdcon[s].c_data);
fdcon[s].c_status = CS_UNUSED;
fdcon[s].c_keytype = 0;
TAILQ_REMOVE(&tq, &fdcon[s], c_link);
FD_CLR(s, read_wait);
ncon--;
}
static void
contouch(int s)
{
TAILQ_REMOVE(&tq, &fdcon[s], c_link);
gettimeofday(&fdcon[s].c_tv, NULL);
fdcon[s].c_tv.tv_sec += timeout;
TAILQ_INSERT_TAIL(&tq, &fdcon[s], c_link);
}
static int
conrecycle(int s)
{
int ret;
con *c = &fdcon[s];
ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
confree(s);
return (ret);
}
static void
congreet(int s)
{
char buf[256], *cp;
size_t bufsiz;
int n = 0;
con *c = &fdcon[s];
bufsiz = sizeof(buf);
cp = buf;
while (bufsiz-- && (n = read(s, cp, 1)) == 1 && *cp != '\n') {
if (*cp == '\r')
*cp = '\n';
cp++;
}
if (n < 0) {
if (errno != ECONNREFUSED)
error("read (%s): %s", c->c_name, strerror(errno));
conrecycle(s);
return;
}
if (*cp != '\n' && *cp != '\r') {
error("%s: bad greeting", c->c_name);
confree(s);
return;
}
*cp = '\0';
if (c->c_keytype != KT_RSA1) {
int remote_major, remote_minor;
char remote_version[sizeof buf];
if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
&remote_major, &remote_minor, remote_version) == 3)
compat_datafellows(remote_version);
else
datafellows = 0;
if (!ssh2_capable(remote_major, remote_minor)) {
debug("%s doesn't support ssh2", c->c_name);
confree(s);
return;
}
}
fprintf(stderr, "# %s %s\n", c->c_name, chop(buf));
n = snprintf(buf, sizeof buf, "SSH-%d.%d-OpenSSH-keyscan\r\n",
c->c_keytype == KT_RSA1? PROTOCOL_MAJOR_1 : PROTOCOL_MAJOR_2,
c->c_keytype == KT_RSA1? PROTOCOL_MINOR_1 : PROTOCOL_MINOR_2);
if (atomicio(write, s, buf, n) != n) {
error("write (%s): %s", c->c_name, strerror(errno));
confree(s);
return;
}
if (c->c_keytype != KT_RSA1) {
keyprint(c, keygrab_ssh2(c));
confree(s);
return;
}
c->c_status = CS_SIZE;
contouch(s);
}
static void
conread(int s)
{
int n;
con *c = &fdcon[s];
if (c->c_status == CS_CON) {
congreet(s);
return;
}
n = read(s, c->c_data + c->c_off, c->c_len - c->c_off);
if (n < 0) {
error("read (%s): %s", c->c_name, strerror(errno));
confree(s);
return;
}
c->c_off += n;
if (c->c_off == c->c_len)
switch (c->c_status) {
case CS_SIZE:
c->c_plen = htonl(c->c_plen);
c->c_len = c->c_plen + 8 - (c->c_plen & 7);
c->c_off = 0;
c->c_data = xmalloc(c->c_len);
c->c_status = CS_KEYS;
break;
case CS_KEYS:
keyprint(c, keygrab_ssh1(c));
confree(s);
return;
break;
default:
fatal("conread: invalid status %d", c->c_status);
break;
}
contouch(s);
}
static void
conloop(void)
{
fd_set *r, *e;
struct timeval seltime, now;
int i;
con *c;
gettimeofday(&now, NULL);
c = tq.tqh_first;
if (c && (c->c_tv.tv_sec > now.tv_sec ||
(c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec > now.tv_usec))) {
seltime = c->c_tv;
seltime.tv_sec -= now.tv_sec;
seltime.tv_usec -= now.tv_usec;
if (seltime.tv_usec < 0) {
seltime.tv_usec += 1000000;
seltime.tv_sec--;
}
} else
seltime.tv_sec = seltime.tv_usec = 0;
r = xmalloc(read_wait_size);
memcpy(r, read_wait, read_wait_size);
e = xmalloc(read_wait_size);
memcpy(e, read_wait, read_wait_size);
while (select(maxfd, r, NULL, e, &seltime) == -1 &&
(errno == EAGAIN || errno == EINTR))
;
for (i = 0; i < maxfd; i++) {
if (FD_ISSET(i, e)) {
error("%s: exception!", fdcon[i].c_name);
confree(i);
} else if (FD_ISSET(i, r))
conread(i);
}
xfree(r);
xfree(e);
c = tq.tqh_first;
while (c && (c->c_tv.tv_sec < now.tv_sec ||
(c->c_tv.tv_sec == now.tv_sec && c->c_tv.tv_usec < now.tv_usec))) {
int s = c->c_fd;
c = c->c_link.tqe_next;
conrecycle(s);
}
}
static void
do_host(char *host)
{
char *name = strnnsep(&host, " \t\n");
int j;
for (j = KT_RSA1; j <= KT_RSA; j *= 2) {
if (get_keytypes & j) {
while (ncon >= MAXCON)
conloop();
conalloc(name, *host ? host : name, j);
}
}
}
static void
fatal_callback(void *arg)
{
if (nonfatal_fatal)
longjmp(kexjmp, -1);
}
static void
usage(void)
{
fprintf(stderr, "Usage: %s [options] host ...\n",
__progname);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -f file Read hosts or addresses from file.\n");
fprintf(stderr, " -p port Connect to the specified port.\n");
fprintf(stderr, " -t keytype Specify the host key type.\n");
fprintf(stderr, " -T timeout Set connection timeout.\n");
fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
fprintf(stderr, " -4 Use IPv4 only.\n");
fprintf(stderr, " -6 Use IPv6 only.\n");
exit(1);
}
int
main(int argc, char **argv)
{
int debug_flag = 0, log_level = SYSLOG_LEVEL_INFO;
int opt, fopt_count = 0;
char *tname;
extern int optind;
extern char *optarg;
__progname = get_progname(argv[0]);
TAILQ_INIT(&tq);
if (argc <= 1)
usage();
while ((opt = getopt(argc, argv, "v46p:T:t:f:")) != -1) {
switch (opt) {
case 'p':
ssh_port = a2port(optarg);
if (ssh_port == 0) {
fprintf(stderr, "Bad port '%s'\n", optarg);
exit(1);
}
break;
case 'T':
timeout = atoi(optarg);
if (timeout <= 0)
usage();
break;
case 'v':
if (!debug_flag) {
debug_flag = 1;
log_level = SYSLOG_LEVEL_DEBUG1;
}
else if (log_level < SYSLOG_LEVEL_DEBUG3)
log_level++;
else
fatal("Too high debugging level.");
break;
case 'f':
if (strcmp(optarg, "-") == 0)
optarg = NULL;
argv[fopt_count++] = optarg;
break;
case 't':
get_keytypes = 0;
tname = strtok(optarg, ",");
while (tname) {
int type = key_type_from_name(tname);
switch (type) {
case KEY_RSA1:
get_keytypes |= KT_RSA1;
break;
case KEY_DSA:
get_keytypes |= KT_DSA;
break;
case KEY_RSA:
get_keytypes |= KT_RSA;
break;
case KEY_UNSPEC:
fatal("unknown key type %s\n", tname);
}
tname = strtok(NULL, ",");
}
break;
case '4':
IPv4or6 = AF_INET;
break;
case '6':
IPv4or6 = AF_INET6;
break;
case '?':
default:
usage();
}
}
if (optind == argc && !fopt_count)
usage();
log_init("ssh-keyscan", log_level, SYSLOG_FACILITY_USER, 1);
fatal_add_cleanup(fatal_callback, NULL);
maxfd = fdlim_get(1);
if (maxfd < 0)
fatal("%s: fdlim_get: bad value", __progname);
if (maxfd > MAXMAXFD)
maxfd = MAXMAXFD;
if (MAXCON <= 0)
fatal("%s: not enough file descriptors", __progname);
if (maxfd > fdlim_get(0))
fdlim_set(maxfd);
fdcon = xmalloc(maxfd * sizeof(con));
memset(fdcon, 0, maxfd * sizeof(con));
read_wait_size = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
read_wait = xmalloc(read_wait_size);
memset(read_wait, 0, read_wait_size);
if (fopt_count) {
Linebuf *lb;
char *line;
int j;
for (j = 0; j < fopt_count; j++) {
lb = Linebuf_alloc(argv[j], error);
if (!lb)
continue;
while ((line = Linebuf_getline(lb)) != NULL)
do_host(line);
Linebuf_free(lb);
}
}
while (optind < argc)
do_host(argv[optind++]);
while (ncon > 0)
conloop();
return (0);
}
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