Return to ssh-keyscan.c CVS log

Up to [local] / src / usr.bin / ssh

make a2port() return -1 when it encounters an invalid port number
rather than 0, which it will now treat as valid (needed for future work)

adjust current consumers of a2port() to check its return value is <= 0,
which in turn required some things to be converted from u_short => int

make use of int vs. u_short consistent in some other places too

feedback & ok markus@

/* $OpenBSD: ssh-keyscan.c,v 1.78 2009/01/22 10:02:34 djm Exp $ */
/*
 * 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <sys/time.h>
#include <sys/resource.h>

#include <openssl/bn.h>

#include <errno.h>
#include <netdb.h>
#include <setjmp.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "ssh.h"
#include "ssh1.h"
#include "buffer.h"
#include "key.h"
#include "cipher.h"
#include "kex.h"
#include "compat.h"
#include "myproposal.h"
#include "packet.h"
#include "dispatch.h"
#include "log.h"
#include "atomicio.h"
#include "misc.h"
#include "hostfile.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. */
int IPv4or6 = AF_UNSPEC;

int ssh_port = SSH_DEFAULT_PORT;

#define KT_RSA1	1
#define KT_DSA	2
#define KT_RSA	4

int get_keytypes = KT_RSA;	/* Get only RSA keys by default */

int hash_hosts = 0;		/* Hash hostname on output */

#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)

extern char *__progname;
fd_set *read_wait;
size_t read_wait_nfdset;
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",
			    filename ? filename : "(stdin)");
		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)
{
	size_t n = 0;
	void *p;

	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 */
		lb->size *= 2;
		if ((p = realloc(lb->buf, lb->size)) == NULL) {
			lb->size /= 2;
			if (lb->errfun)
				(*lb->errfun)("linebuf (%s): realloc failed\n",
				    lb->filename);
			return (NULL);
		}
		lb->buf = p;
	}
}

static int
fdlim_get(int hard)
{
	struct rlimit rlfd;

	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	if ((hard ? rlfd.rlim_max : rlfd.rlim_cur) == RLIM_INFINITY)
		return sysconf(_SC_OPEN_MAX);
	else
		return hard ? rlfd.rlim_max : rlfd.rlim_cur;
}

static int
fdlim_set(int lim)
{
	struct rlimit rlfd;

	if (lim <= 0)
		return (-1);
	if (getrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	rlfd.rlim_cur = lim;
	if (setrlimit(RLIMIT_NOFILE, &rlfd) < 0)
		return (-1);
	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->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
	c->c_kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
	c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
	c->c_kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
	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)
{
	char *host = c->c_output_name ? c->c_output_name : c->c_name;

	if (!key)
		return;
	if (hash_hosts && (host = host_hash(host, NULL, 0)) == NULL)
		fatal("host_hash failed");

	fprintf(stdout, "%s ", host);
	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, ssh_gai_strerror(gaierr));
	for (ai = aitop; ai; ai = ai->ai_next) {
		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
		if (s < 0) {
			error("socket: %s", strerror(errno));
			continue;
		}
		if (set_nonblock(s) == -1)
			fatal("%s: set_nonblock(%d)", __func__, s);
		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)
{
	char *namebase, *name, *namelist;
	int s;

	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)
{
	con *c = &fdcon[s];
	int ret;

	ret = conalloc(c->c_namelist, c->c_output_name, c->c_keytype);
	confree(s);
	return (ret);
}

static void
congreet(int s)
{
	int n = 0, remote_major = 0, remote_minor = 0;
	char buf[256], *cp;
	char remote_version[sizeof buf];
	size_t bufsiz;
	con *c = &fdcon[s];

	for (;;) {
		memset(buf, '\0', sizeof(buf));
		bufsiz = sizeof(buf);
		cp = buf;
		while (bufsiz-- &&
		    (n = atomicio(read, s, cp, 1)) == 1 && *cp != '\n') {
			if (*cp == '\r')
				*cp = '\n';
			cp++;
		}
		if (n != 1 || strncmp(buf, "SSH-", 4) == 0)
			break;
	}
	if (n == 0) {
		switch (errno) {
		case EPIPE:
			error("%s: Connection closed by remote host", c->c_name);
			break;
		case ECONNREFUSED:
			break;
		default:
			error("read (%s): %s", c->c_name, strerror(errno));
			break;
		}
		conrecycle(s);
		return;
	}
	if (*cp != '\n' && *cp != '\r') {
		error("%s: bad greeting", c->c_name);
		confree(s);
		return;
	}
	*cp = '\0';
	if (sscanf(buf, "SSH-%d.%d-%[^\n]\n",
	    &remote_major, &remote_minor, remote_version) == 3)
		compat_datafellows(remote_version);
	else
		datafellows = 0;
	if (c->c_keytype != KT_RSA1) {
		if (!ssh2_capable(remote_major, remote_minor)) {
			debug("%s doesn't support ssh2", c->c_name);
			confree(s);
			return;
		}
	} else if (remote_major != 1) {
		debug("%s doesn't support ssh1", 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 (n < 0 || (size_t)n >= sizeof(buf)) {
		error("snprintf: buffer too small");
		confree(s);
		return;
	}
	if (atomicio(vwrite, s, buf, n) != (size_t)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)
{
	con *c = &fdcon[s];
	size_t n;

	if (c->c_status == CS_CON) {
		congreet(s);
		return;
	}
	n = atomicio(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;
		default:
			fatal("conread: invalid status %d", c->c_status);
			break;
		}

	contouch(s);
}

static void
conloop(void)
{
	struct timeval seltime, now;
	fd_set *r, *e;
	con *c;
	int i;

	gettimeofday(&now, NULL);
	c = TAILQ_FIRST(&tq);

	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 = xcalloc(read_wait_nfdset, sizeof(fd_mask));
	e = xcalloc(read_wait_nfdset, sizeof(fd_mask));
	memcpy(r, read_wait, read_wait_nfdset * sizeof(fd_mask));
	memcpy(e, read_wait, read_wait_nfdset * sizeof(fd_mask));

	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 = TAILQ_FIRST(&tq);
	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 = TAILQ_NEXT(c, c_link);
		conrecycle(s);
	}
}

static void
do_host(char *host)
{
	char *name = strnnsep(&host, " \t\n");
	int j;

	if (name == NULL)
		return;
	for (j = KT_RSA1; j <= KT_RSA; j *= 2) {
		if (get_keytypes & j) {
			while (ncon >= MAXCON)
				conloop();
			conalloc(name, *host ? host : name, j);
		}
	}
}

void
fatal(const char *fmt,...)
{
	va_list args;

	va_start(args, fmt);
	do_log(SYSLOG_LEVEL_FATAL, fmt, args);
	va_end(args);
	if (nonfatal_fatal)
		longjmp(kexjmp, -1);
	else
		exit(255);
}

static void
usage(void)
{
	fprintf(stderr,
	    "usage: %s [-46Hv] [-f file] [-p port] [-T timeout] [-t type]\n"
	    "\t\t   [host | addrlist namelist] ...\n",
	    __progname);
	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;

	TAILQ_INIT(&tq);

	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
	sanitise_stdfd();

	if (argc <= 1)
		usage();

	while ((opt = getopt(argc, argv, "Hv46p:T:t:f:")) != -1) {
		switch (opt) {
		case 'H':
			hash_hosts = 1;
			break;
		case 'p':
			ssh_port = a2port(optarg);
			if (ssh_port <= 0) {
				fprintf(stderr, "Bad port '%s'\n", optarg);
				exit(1);
			}
			break;
		case 'T':
			timeout = convtime(optarg);
			if (timeout == -1 || timeout == 0) {
				fprintf(stderr, "Bad timeout '%s'\n", optarg);
				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", 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);

	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 = xcalloc(maxfd, sizeof(con));

	read_wait_nfdset = howmany(maxfd, NFDBITS);
	read_wait = xcalloc(read_wait_nfdset, sizeof(fd_mask));

	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);
}