[openssh.git] / ssh-agent.c

/*	$OpenBSD: ssh-agent.c,v 1.23 1999/11/24 19:53:51 markus Exp $	*/

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Created: Wed Mar 29 03:46:59 1995 ylo
 * The authentication agent program.
 */

#include "includes.h"
RCSID("$OpenBSD: ssh-agent.c,v 1.23 1999/11/24 19:53:51 markus Exp $");

#include "ssh.h"
#include "rsa.h"
#include "authfd.h"
#include "buffer.h"
#include "bufaux.h"
#include "xmalloc.h"
#include "packet.h"
#include "getput.h"
#include "mpaux.h"

#ifdef HAVE_OPENSSL
#include <openssl/md5.h>
#endif
#ifdef HAVE_SSL
#include <ssl/md5.h>
#endif

typedef struct {
	int fd;
	enum {
		AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
	} type;
	Buffer input;
	Buffer output;
} SocketEntry;

unsigned int sockets_alloc = 0;
SocketEntry *sockets = NULL;

typedef struct {
	RSA *key;
	char *comment;
} Identity;

unsigned int num_identities = 0;
Identity *identities = NULL;

int max_fd = 0;

/* pid of shell == parent of agent */
int parent_pid = -1;

/* pathname and directory for AUTH_SOCKET */
char socket_name[1024];
char socket_dir[1024];

#ifdef HAVE___PROGNAME
extern char *__progname;
#else /* HAVE___PROGNAME */
const char *__progname = "ssh-agent";
#endif /* HAVE___PROGNAME */

void
process_request_identity(SocketEntry *e)
{
	Buffer msg;
	int i;

	buffer_init(&msg);
	buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER);
	buffer_put_int(&msg, num_identities);
	for (i = 0; i < num_identities; i++) {
		buffer_put_int(&msg, BN_num_bits(identities[i].key->n));
		buffer_put_bignum(&msg, identities[i].key->e);
		buffer_put_bignum(&msg, identities[i].key->n);
		buffer_put_string(&msg, identities[i].comment,
				  strlen(identities[i].comment));
	}
	buffer_put_int(&e->output, buffer_len(&msg));
	buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
	buffer_free(&msg);
}

void
process_authentication_challenge(SocketEntry *e)
{
	int i, pub_bits, len;
	BIGNUM *pub_e, *pub_n, *challenge;
	Buffer msg;
	MD5_CTX md;
	unsigned char buf[32], mdbuf[16], session_id[16];
	unsigned int response_type;

	buffer_init(&msg);
	pub_e = BN_new();
	pub_n = BN_new();
	challenge = BN_new();
	pub_bits = buffer_get_int(&e->input);
	buffer_get_bignum(&e->input, pub_e);
	buffer_get_bignum(&e->input, pub_n);
	buffer_get_bignum(&e->input, challenge);
	if (buffer_len(&e->input) == 0) {
		/* Compatibility code for old servers. */
		memset(session_id, 0, 16);
		response_type = 0;
	} else {
		/* New code. */
		buffer_get(&e->input, (char *) session_id, 16);
		response_type = buffer_get_int(&e->input);
	}
	for (i = 0; i < num_identities; i++)
		if (pub_bits == BN_num_bits(identities[i].key->n) &&
		    BN_cmp(pub_e, identities[i].key->e) == 0 &&
		    BN_cmp(pub_n, identities[i].key->n) == 0) {
			/* Decrypt the challenge using the private key. */
			rsa_private_decrypt(challenge, challenge, identities[i].key);

			/* Compute the desired response. */
			switch (response_type) {
			case 0:/* As of protocol 1.0 */
				/* This response type is no longer supported. */
				log("Compatibility with ssh protocol 1.0 no longer supported.");
				buffer_put_char(&msg, SSH_AGENT_FAILURE);
				goto send;

			case 1:/* As of protocol 1.1 */
				/* The response is MD5 of decrypted challenge plus session id. */
				len = BN_num_bytes(challenge);

				if (len <= 0 || len > 32) {
					fatal("process_authentication_challenge: "
					 "bad challenge length %d", len);
				}
				memset(buf, 0, 32);
				BN_bn2bin(challenge, buf + 32 - len);
				MD5_Init(&md);
				MD5_Update(&md, buf, 32);
				MD5_Update(&md, session_id, 16);
				MD5_Final(mdbuf, &md);
				break;

			default:
				fatal("process_authentication_challenge: bad response_type %d",
				      response_type);
				break;
			}

			/* Send the response. */
			buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
			for (i = 0; i < 16; i++)
				buffer_put_char(&msg, mdbuf[i]);

			goto send;
		}
	/* Unknown identity.  Send failure. */
	buffer_put_char(&msg, SSH_AGENT_FAILURE);
send:
	buffer_put_int(&e->output, buffer_len(&msg));
	buffer_append(&e->output, buffer_ptr(&msg),
		      buffer_len(&msg));
	buffer_free(&msg);
	BN_clear_free(pub_e);
	BN_clear_free(pub_n);
	BN_clear_free(challenge);
}

void
process_remove_identity(SocketEntry *e)
{
	unsigned int bits;
	unsigned int i;
	BIGNUM *dummy, *n;

	dummy = BN_new();
	n = BN_new();

	/* Get the key from the packet. */
	bits = buffer_get_int(&e->input);
	buffer_get_bignum(&e->input, dummy);
	buffer_get_bignum(&e->input, n);

	if (bits != BN_num_bits(n))
		error("Warning: keysize mismatch: actual %d, announced %d",
		      BN_num_bits(n), bits);

	/* Check if we have the key. */
	for (i = 0; i < num_identities; i++)
		if (BN_cmp(identities[i].key->n, n) == 0) {
			/*
			 * We have this key.  Free the old key.  Since we
			 * don\'t want to leave empty slots in the middle of
			 * the array, we actually free the key there and copy
			 * data from the last entry.
			 */
			RSA_free(identities[i].key);
			xfree(identities[i].comment);
			if (i < num_identities - 1)
				identities[i] = identities[num_identities - 1];
			num_identities--;
			BN_clear_free(dummy);
			BN_clear_free(n);

			/* Send success. */
			buffer_put_int(&e->output, 1);
			buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
			return;
		}
	/* We did not have the key. */
	BN_clear(dummy);
	BN_clear(n);

	/* Send failure. */
	buffer_put_int(&e->output, 1);
	buffer_put_char(&e->output, SSH_AGENT_FAILURE);
}

/*
 * Removes all identities from the agent.
 */
void
process_remove_all_identities(SocketEntry *e)
{
	unsigned int i;

	/* Loop over all identities and clear the keys. */
	for (i = 0; i < num_identities; i++) {
		RSA_free(identities[i].key);
		xfree(identities[i].comment);
	}

	/* Mark that there are no identities. */
	num_identities = 0;

	/* Send success. */
	buffer_put_int(&e->output, 1);
	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	return;
}

/*
 * Adds an identity to the agent.
 */
void
process_add_identity(SocketEntry *e)
{
	RSA *k;
	int i;
	BIGNUM *aux;
	BN_CTX *ctx;

	if (num_identities == 0)
		identities = xmalloc(sizeof(Identity));
	else
		identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity));

	identities[num_identities].key = RSA_new();
	k = identities[num_identities].key;
	buffer_get_int(&e->input);	/* bits */
	k->n = BN_new();
	buffer_get_bignum(&e->input, k->n);
	k->e = BN_new();
	buffer_get_bignum(&e->input, k->e);
	k->d = BN_new();
	buffer_get_bignum(&e->input, k->d);
	k->iqmp = BN_new();
	buffer_get_bignum(&e->input, k->iqmp);
	/* SSH and SSL have p and q swapped */
	k->q = BN_new();
	buffer_get_bignum(&e->input, k->q);	/* p */
	k->p = BN_new();
	buffer_get_bignum(&e->input, k->p);	/* q */

	/* Generate additional parameters */
	aux = BN_new();
	ctx = BN_CTX_new();

	BN_sub(aux, k->q, BN_value_one());
	k->dmq1 = BN_new();
	BN_mod(k->dmq1, k->d, aux, ctx);

	BN_sub(aux, k->p, BN_value_one());
	k->dmp1 = BN_new();
	BN_mod(k->dmp1, k->d, aux, ctx);

	BN_clear_free(aux);
	BN_CTX_free(ctx);

	identities[num_identities].comment = buffer_get_string(&e->input, NULL);

	/* Check if we already have the key. */
	for (i = 0; i < num_identities; i++)
		if (BN_cmp(identities[i].key->n, k->n) == 0) {
			/*
			 * We already have this key.  Clear and free the new
			 * data and return success.
			 */
			RSA_free(k);
			xfree(identities[num_identities].comment);

			/* Send success. */
			buffer_put_int(&e->output, 1);
			buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
			return;
		}
	/* Increment the number of identities. */
	num_identities++;

	/* Send a success message. */
	buffer_put_int(&e->output, 1);
	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
}

void
process_message(SocketEntry *e)
{
	unsigned int msg_len;
	unsigned int type;
	unsigned char *cp;
	if (buffer_len(&e->input) < 5)
		return;		/* Incomplete message. */
	cp = (unsigned char *) buffer_ptr(&e->input);
	msg_len = GET_32BIT(cp);
	if (msg_len > 256 * 1024) {
		shutdown(e->fd, SHUT_RDWR);
		close(e->fd);
		e->type = AUTH_UNUSED;
		return;
	}
	if (buffer_len(&e->input) < msg_len + 4)
		return;
	buffer_consume(&e->input, 4);
	type = buffer_get_char(&e->input);

	switch (type) {
	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
		process_request_identity(e);
		break;
	case SSH_AGENTC_RSA_CHALLENGE:
		process_authentication_challenge(e);
		break;
	case SSH_AGENTC_ADD_RSA_IDENTITY:
		process_add_identity(e);
		break;
	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
		process_remove_identity(e);
		break;
	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
		process_remove_all_identities(e);
		break;
	default:
		/* Unknown message.  Respond with failure. */
		error("Unknown message %d", type);
		buffer_clear(&e->input);
		buffer_put_int(&e->output, 1);
		buffer_put_char(&e->output, SSH_AGENT_FAILURE);
		break;
	}
}

void
new_socket(int type, int fd)
{
	unsigned int i, old_alloc;
	if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
		error("fcntl O_NONBLOCK: %s", strerror(errno));

	if (fd > max_fd)
		max_fd = fd;

	for (i = 0; i < sockets_alloc; i++)
		if (sockets[i].type == AUTH_UNUSED) {
			sockets[i].fd = fd;
			sockets[i].type = type;
			buffer_init(&sockets[i].input);
			buffer_init(&sockets[i].output);
			return;
		}
	old_alloc = sockets_alloc;
	sockets_alloc += 10;
	if (sockets)
		sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
	else
		sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
	for (i = old_alloc; i < sockets_alloc; i++)
		sockets[i].type = AUTH_UNUSED;
	sockets[old_alloc].type = type;
	sockets[old_alloc].fd = fd;
	buffer_init(&sockets[old_alloc].input);
	buffer_init(&sockets[old_alloc].output);
}

void
prepare_select(fd_set *readset, fd_set *writeset)
{
	unsigned int i;
	for (i = 0; i < sockets_alloc; i++)
		switch (sockets[i].type) {
		case AUTH_SOCKET:
		case AUTH_CONNECTION:
			FD_SET(sockets[i].fd, readset);
			if (buffer_len(&sockets[i].output) > 0)
				FD_SET(sockets[i].fd, writeset);
			break;
		case AUTH_UNUSED:
			break;
		default:
			fatal("Unknown socket type %d", sockets[i].type);
			break;
		}
}

void 
after_select(fd_set *readset, fd_set *writeset)
{
	unsigned int i;
	int len, sock;
	char buf[1024];
	struct sockaddr_un sunaddr;

	for (i = 0; i < sockets_alloc; i++)
		switch (sockets[i].type) {
		case AUTH_UNUSED:
			break;
		case AUTH_SOCKET:
			if (FD_ISSET(sockets[i].fd, readset)) {
				len = sizeof(sunaddr);
				sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len);
				if (sock < 0) {
					perror("accept from AUTH_SOCKET");
					break;
				}
				new_socket(AUTH_CONNECTION, sock);
			}
			break;
		case AUTH_CONNECTION:
			if (buffer_len(&sockets[i].output) > 0 &&
			    FD_ISSET(sockets[i].fd, writeset)) {
				len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
					 buffer_len(&sockets[i].output));
				if (len <= 0) {
					shutdown(sockets[i].fd, SHUT_RDWR);
					close(sockets[i].fd);
					sockets[i].type = AUTH_UNUSED;
					break;
				}
				buffer_consume(&sockets[i].output, len);
			}
			if (FD_ISSET(sockets[i].fd, readset)) {
				len = read(sockets[i].fd, buf, sizeof(buf));
				if (len <= 0) {
					shutdown(sockets[i].fd, SHUT_RDWR);
					close(sockets[i].fd);
					sockets[i].type = AUTH_UNUSED;
					break;
				}
				buffer_append(&sockets[i].input, buf, len);
				process_message(&sockets[i]);
			}
			break;
		default:
			fatal("Unknown type %d", sockets[i].type);
		}
}

void
check_parent_exists(int sig)
{
	if (kill(parent_pid, 0) < 0) {
		/* printf("Parent has died - Authentication agent exiting.\n"); */
		exit(1);
	}
	signal(SIGALRM, check_parent_exists);
	alarm(10);
}

void
cleanup_socket(void)
{
	remove(socket_name);
	rmdir(socket_dir);
}

void
cleanup_exit(int i)
{
	cleanup_socket();
	exit(i);
}

void
usage()
{
	fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
	fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
		__progname);
	exit(1);
}

int
main(int ac, char **av)
{
	fd_set readset, writeset;
	int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
	struct sockaddr_un sunaddr;
	pid_t pid;
	char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];

	/* check if RSA support exists */
	if (rsa_alive() == 0) {
		fprintf(stderr,
			"%s: no RSA support in libssl and libcrypto.  See ssl(8).\n",
			__progname);
		exit(1);
	}
	while ((ch = getopt(ac, av, "cks")) != -1) {
		switch (ch) {
		case 'c':
			if (s_flag)
				usage();
			c_flag++;
			break;
		case 'k':
			k_flag++;
			break;
		case 's':
			if (c_flag)
				usage();
			s_flag++;
			break;
		default:
			usage();
		}
	}
	ac -= optind;
	av += optind;

	if (ac > 0 && (c_flag || k_flag || s_flag))
		usage();

	if (ac == 0 && !c_flag && !k_flag && !s_flag) {
		shell = getenv("SHELL");
		if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
			c_flag = 1;
	}
	if (k_flag) {
		pidstr = getenv(SSH_AGENTPID_ENV_NAME);
		if (pidstr == NULL) {
			fprintf(stderr, "%s not set, cannot kill agent\n",
				SSH_AGENTPID_ENV_NAME);
			exit(1);
		}
		pid = atoi(pidstr);
		if (pid < 1) {	/* XXX PID_MAX check too */
			fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
				SSH_AGENTPID_ENV_NAME, pidstr);
			exit(1);
		}
		if (kill(pid, SIGTERM) == -1) {
			perror("kill");
			exit(1);
		}
		format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
		printf(format, SSH_AUTHSOCKET_ENV_NAME);
		printf(format, SSH_AGENTPID_ENV_NAME);
		printf("echo Agent pid %d killed;\n", pid);
		exit(0);
	}
	parent_pid = getpid();

	/* Create private directory for agent socket */
	strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
	if (mkdtemp(socket_dir) == NULL) {
		perror("mkdtemp: private socket dir");
		exit(1);
	}
	snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
		 parent_pid);

	/*
	 * Create socket early so it will exist before command gets run from
	 * the parent.
	 */
	sock = socket(AF_UNIX, SOCK_STREAM, 0);
	if (sock < 0) {
		perror("socket");
		cleanup_exit(1);
	}
	memset(&sunaddr, 0, sizeof(sunaddr));
	sunaddr.sun_family = AF_UNIX;
	strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
	if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
		perror("bind");
		cleanup_exit(1);
	}
	if (listen(sock, 5) < 0) {
		perror("listen");
		cleanup_exit(1);
	}
	/*
	 * Fork, and have the parent execute the command, if any, or present
	 * the socket data.  The child continues as the authentication agent.
	 */
	pid = fork();
	if (pid == -1) {
		perror("fork");
		exit(1);
	}
	if (pid != 0) {		/* Parent - execute the given command. */
		close(sock);
		snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
		if (ac == 0) {
			format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
			printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
			       SSH_AUTHSOCKET_ENV_NAME);
			printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
			       SSH_AGENTPID_ENV_NAME);
			printf("echo Agent pid %d;\n", pid);
			exit(0);
		}
		setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1);
		setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1);
		execvp(av[0], av);
		perror(av[0]);
		exit(1);
	}
	close(0);
	close(1);
	close(2);

	if (setsid() == -1) {
		perror("setsid");
		cleanup_exit(1);
	}
	if (atexit(cleanup_socket) < 0) {
		perror("atexit");
		cleanup_exit(1);
	}
	new_socket(AUTH_SOCKET, sock);
	if (ac > 0) {
		signal(SIGALRM, check_parent_exists);
		alarm(10);
	}
	signal(SIGINT, SIG_IGN);
	signal(SIGPIPE, SIG_IGN);
	while (1) {
		FD_ZERO(&readset);
		FD_ZERO(&writeset);
		prepare_select(&readset, &writeset);
		if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
			if (errno == EINTR)
				continue;
			exit(1);
		}
		after_select(&readset, &writeset);
	}
	/* NOTREACHED */
}
Commit	Line	Data
aa3378df	1	/* $OpenBSD: ssh-agent.c,v 1.23 1999/11/24 19:53:51 markus Exp $ */
dae3fa13	2
8efc0c15	3	/*
5260325f	4	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	5	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	6	* All rights reserved
	7	* Created: Wed Mar 29 03:46:59 1995 ylo
	8	* The authentication agent program.
	9	*/
8efc0c15	10
8efc0c15	11	#include "includes.h"
aa3378df	12	RCSID("$OpenBSD: ssh-agent.c,v 1.23 1999/11/24 19:53:51 markus Exp $");
8efc0c15	13
	14	#include "ssh.h"
	15	#include "rsa.h"
	16	#include "authfd.h"
	17	#include "buffer.h"
	18	#include "bufaux.h"
	19	#include "xmalloc.h"
	20	#include "packet.h"
	21	#include "getput.h"
	22	#include "mpaux.h"
	23
5881cd60	24	#ifdef HAVE_OPENSSL
8efc0c15	25	#include <openssl/md5.h>
5881cd60	26	#endif
	27	#ifdef HAVE_SSL
	28	#include <ssl/md5.h>
	29	#endif
8efc0c15	30
5260325f	31	typedef struct {
	32	int fd;
	33	enum {
	34	AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
	35	} type;
	36	Buffer input;
	37	Buffer output;
8efc0c15	38	} SocketEntry;
	39
	40	unsigned int sockets_alloc = 0;
	41	SocketEntry *sockets = NULL;
	42
5260325f	43	typedef struct {
	44	RSA *key;
	45	char *comment;
8efc0c15	46	} Identity;
	47
	48	unsigned int num_identities = 0;
	49	Identity *identities = NULL;
	50
	51	int max_fd = 0;
	52
	53	/* pid of shell == parent of agent */
	54	int parent_pid = -1;
	55
	56	/* pathname and directory for AUTH_SOCKET */
	57	char socket_name[1024];
	58	char socket_dir[1024];
	59
5260325f	60	#ifdef HAVE___PROGNAME
	61	extern char *__progname;
	62	#else /* HAVE___PROGNAME */
	63	const char *__progname = "ssh-agent";
	64	#endif /* HAVE___PROGNAME */
	65
8efc0c15	66	void
	67	process_request_identity(SocketEntry *e)
	68	{
5260325f	69	Buffer msg;
	70	int i;
	71
	72	buffer_init(&msg);
	73	buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER);
	74	buffer_put_int(&msg, num_identities);
	75	for (i = 0; i < num_identities; i++) {
	76	buffer_put_int(&msg, BN_num_bits(identities[i].key->n));
	77	buffer_put_bignum(&msg, identities[i].key->e);
	78	buffer_put_bignum(&msg, identities[i].key->n);
	79	buffer_put_string(&msg, identities[i].comment,
	80	strlen(identities[i].comment));
	81	}
	82	buffer_put_int(&e->output, buffer_len(&msg));
	83	buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
	84	buffer_free(&msg);
8efc0c15	85	}
	86
	87	void
	88	process_authentication_challenge(SocketEntry *e)
	89	{
5260325f	90	int i, pub_bits, len;
	91	BIGNUM pub_e, pub_n, *challenge;
	92	Buffer msg;
	93	MD5_CTX md;
	94	unsigned char buf[32], mdbuf[16], session_id[16];
	95	unsigned int response_type;
	96
	97	buffer_init(&msg);
	98	pub_e = BN_new();
	99	pub_n = BN_new();
	100	challenge = BN_new();
	101	pub_bits = buffer_get_int(&e->input);
	102	buffer_get_bignum(&e->input, pub_e);
	103	buffer_get_bignum(&e->input, pub_n);
	104	buffer_get_bignum(&e->input, challenge);
	105	if (buffer_len(&e->input) == 0) {
	106	/* Compatibility code for old servers. */
	107	memset(session_id, 0, 16);
	108	response_type = 0;
	109	} else {
	110	/* New code. */
	111	buffer_get(&e->input, (char *) session_id, 16);
	112	response_type = buffer_get_int(&e->input);
	113	}
	114	for (i = 0; i < num_identities; i++)
	115	if (pub_bits == BN_num_bits(identities[i].key->n) &&
	116	BN_cmp(pub_e, identities[i].key->e) == 0 &&
	117	BN_cmp(pub_n, identities[i].key->n) == 0) {
	118	/* Decrypt the challenge using the private key. */
	119	rsa_private_decrypt(challenge, challenge, identities[i].key);
	120
	121	/* Compute the desired response. */
	122	switch (response_type) {
	123	case 0:/* As of protocol 1.0 */
	124	/* This response type is no longer supported. */
	125	log("Compatibility with ssh protocol 1.0 no longer supported.");
	126	buffer_put_char(&msg, SSH_AGENT_FAILURE);
	127	goto send;
	128
	129	case 1:/* As of protocol 1.1 */
	130	/* The response is MD5 of decrypted challenge plus session id. */
	131	len = BN_num_bytes(challenge);
	132
	133	if (len <= 0 \|\| len > 32) {
	134	fatal("process_authentication_challenge: "
	135	"bad challenge length %d", len);
	136	}
	137	memset(buf, 0, 32);
	138	BN_bn2bin(challenge, buf + 32 - len);
	139	MD5_Init(&md);
	140	MD5_Update(&md, buf, 32);
	141	MD5_Update(&md, session_id, 16);
	142	MD5_Final(mdbuf, &md);
	143	break;
	144
	145	default:
	146	fatal("process_authentication_challenge: bad response_type %d",
	147	response_type);
	148	break;
	149	}
	150
	151	/* Send the response. */
	152	buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
	153	for (i = 0; i < 16; i++)
154	buffer_put_char(&msg, mdbuf[i]);
155
156	goto send;
157	}
158	/* Unknown identity. Send failure. */
159	buffer_put_char(&msg, SSH_AGENT_FAILURE);
160	send:
161	buffer_put_int(&e->output, buffer_len(&msg));
162	buffer_append(&e->output, buffer_ptr(&msg),
163	buffer_len(&msg));
164	buffer_free(&msg);
165	BN_clear_free(pub_e);
166	BN_clear_free(pub_n);
167	BN_clear_free(challenge);
8efc0c15	168	}
	169
	170	void
	171	process_remove_identity(SocketEntry *e)
	172	{
5260325f	173	unsigned int bits;
	174	unsigned int i;
	175	BIGNUM dummy, n;
	176
	177	dummy = BN_new();
	178	n = BN_new();
	179
	180	/* Get the key from the packet. */
	181	bits = buffer_get_int(&e->input);
	182	buffer_get_bignum(&e->input, dummy);
	183	buffer_get_bignum(&e->input, n);
	184
	185	if (bits != BN_num_bits(n))
	186	error("Warning: keysize mismatch: actual %d, announced %d",
	187	BN_num_bits(n), bits);
	188
	189	/* Check if we have the key. */
	190	for (i = 0; i < num_identities; i++)
	191	if (BN_cmp(identities[i].key->n, n) == 0) {
aa3378df	192	/*
	193	* We have this key. Free the old key. Since we
	194	* don\'t want to leave empty slots in the middle of
	195	* the array, we actually free the key there and copy
	196	* data from the last entry.
	197	*/
5260325f	198	RSA_free(identities[i].key);
	199	xfree(identities[i].comment);
	200	if (i < num_identities - 1)
	201	identities[i] = identities[num_identities - 1];
	202	num_identities--;
	203	BN_clear_free(dummy);
	204	BN_clear_free(n);
	205
	206	/* Send success. */
	207	buffer_put_int(&e->output, 1);
	208	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	209	return;
	210	}
	211	/* We did not have the key. */
	212	BN_clear(dummy);
	213	BN_clear(n);
	214
	215	/* Send failure. */
8efc0c15	216	buffer_put_int(&e->output, 1);
5260325f	217	buffer_put_char(&e->output, SSH_AGENT_FAILURE);
8efc0c15	218	}
8efc0c15	219
5260325f	220	/*
	221	* Removes all identities from the agent.
	222	*/
8efc0c15	223	void
	224	process_remove_all_identities(SocketEntry *e)
	225	{
5260325f	226	unsigned int i;
8efc0c15	227
5260325f	228	/* Loop over all identities and clear the keys. */
	229	for (i = 0; i < num_identities; i++) {
	230	RSA_free(identities[i].key);
	231	xfree(identities[i].comment);
	232	}
8efc0c15	233
5260325f	234	/* Mark that there are no identities. */
5260325f	235	num_identities = 0;
8efc0c15	236
	237	/* Send success. */
	238	buffer_put_int(&e->output, 1);
	239	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	240	return;
5260325f	241	}
	242
	243	/*
	244	* Adds an identity to the agent.
	245	*/
	246	void
	247	process_add_identity(SocketEntry *e)
	248	{
	249	RSA *k;
	250	int i;
	251	BIGNUM *aux;
	252	BN_CTX *ctx;
	253
	254	if (num_identities == 0)
	255	identities = xmalloc(sizeof(Identity));
	256	else
	257	identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity));
	258
	259	identities[num_identities].key = RSA_new();
	260	k = identities[num_identities].key;
	261	buffer_get_int(&e->input); /* bits */
	262	k->n = BN_new();
	263	buffer_get_bignum(&e->input, k->n);
	264	k->e = BN_new();
	265	buffer_get_bignum(&e->input, k->e);
	266	k->d = BN_new();
	267	buffer_get_bignum(&e->input, k->d);
	268	k->iqmp = BN_new();
	269	buffer_get_bignum(&e->input, k->iqmp);
	270	/* SSH and SSL have p and q swapped */
	271	k->q = BN_new();
	272	buffer_get_bignum(&e->input, k->q); /* p */
	273	k->p = BN_new();
	274	buffer_get_bignum(&e->input, k->p); /* q */
	275
	276	/* Generate additional parameters */
	277	aux = BN_new();
	278	ctx = BN_CTX_new();
	279
	280	BN_sub(aux, k->q, BN_value_one());
	281	k->dmq1 = BN_new();
	282	BN_mod(k->dmq1, k->d, aux, ctx);
	283
	284	BN_sub(aux, k->p, BN_value_one());
	285	k->dmp1 = BN_new();
	286	BN_mod(k->dmp1, k->d, aux, ctx);
	287
	288	BN_clear_free(aux);
	289	BN_CTX_free(ctx);
	290
	291	identities[num_identities].comment = buffer_get_string(&e->input, NULL);
	292
	293	/* Check if we already have the key. */
	294	for (i = 0; i < num_identities; i++)
	295	if (BN_cmp(identities[i].key->n, k->n) == 0) {
aa3378df	296	/*
	297	* We already have this key. Clear and free the new
	298	* data and return success.
	299	*/
5260325f	300	RSA_free(k);
	301	xfree(identities[num_identities].comment);
	302
	303	/* Send success. */
	304	buffer_put_int(&e->output, 1);
	305	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	306	return;
	307	}
	308	/* Increment the number of identities. */
	309	num_identities++;
	310
	311	/* Send a success message. */
	312	buffer_put_int(&e->output, 1);
	313	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
8efc0c15	314	}
	315
	316	void
	317	process_message(SocketEntry *e)
	318	{
5260325f	319	unsigned int msg_len;
	320	unsigned int type;
	321	unsigned char *cp;
	322	if (buffer_len(&e->input) < 5)
	323	return; /* Incomplete message. */
	324	cp = (unsigned char *) buffer_ptr(&e->input);
	325	msg_len = GET_32BIT(cp);
	326	if (msg_len > 256 * 1024) {
	327	shutdown(e->fd, SHUT_RDWR);
	328	close(e->fd);
	329	e->type = AUTH_UNUSED;
	330	return;
	331	}
	332	if (buffer_len(&e->input) < msg_len + 4)
	333	return;
	334	buffer_consume(&e->input, 4);
	335	type = buffer_get_char(&e->input);
	336
	337	switch (type) {
	338	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
	339	process_request_identity(e);
	340	break;
	341	case SSH_AGENTC_RSA_CHALLENGE:
	342	process_authentication_challenge(e);
	343	break;
	344	case SSH_AGENTC_ADD_RSA_IDENTITY:
	345	process_add_identity(e);
	346	break;
	347	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
	348	process_remove_identity(e);
	349	break;
	350	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
	351	process_remove_all_identities(e);
	352	break;
	353	default:
	354	/* Unknown message. Respond with failure. */
	355	error("Unknown message %d", type);
	356	buffer_clear(&e->input);
	357	buffer_put_int(&e->output, 1);
	358	buffer_put_char(&e->output, SSH_AGENT_FAILURE);
	359	break;
	360	}
8efc0c15	361	}
	362
	363	void
	364	new_socket(int type, int fd)
	365	{
5260325f	366	unsigned int i, old_alloc;
	367	if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
	368	error("fcntl O_NONBLOCK: %s", strerror(errno));
	369
	370	if (fd > max_fd)
	371	max_fd = fd;
	372
	373	for (i = 0; i < sockets_alloc; i++)
	374	if (sockets[i].type == AUTH_UNUSED) {
	375	sockets[i].fd = fd;
	376	sockets[i].type = type;
	377	buffer_init(&sockets[i].input);
	378	buffer_init(&sockets[i].output);
	379	return;
	380	}
	381	old_alloc = sockets_alloc;
	382	sockets_alloc += 10;
	383	if (sockets)
	384	sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
	385	else
	386	sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
	387	for (i = old_alloc; i < sockets_alloc; i++)
	388	sockets[i].type = AUTH_UNUSED;
	389	sockets[old_alloc].type = type;
	390	sockets[old_alloc].fd = fd;
	391	buffer_init(&sockets[old_alloc].input);
	392	buffer_init(&sockets[old_alloc].output);
8efc0c15	393	}
	394
	395	void
	396	prepare_select(fd_set readset, fd_set writeset)
	397	{
5260325f	398	unsigned int i;
	399	for (i = 0; i < sockets_alloc; i++)
	400	switch (sockets[i].type) {
	401	case AUTH_SOCKET:
	402	case AUTH_CONNECTION:
	403	FD_SET(sockets[i].fd, readset);
	404	if (buffer_len(&sockets[i].output) > 0)
	405	FD_SET(sockets[i].fd, writeset);
	406	break;
	407	case AUTH_UNUSED:
	408	break;
	409	default:
	410	fatal("Unknown socket type %d", sockets[i].type);
	411	break;
	412	}
8efc0c15	413	}
8efc0c15	414
5260325f	415	void
5260325f	416	after_select(fd_set readset, fd_set writeset)
8efc0c15	417	{
5260325f	418	unsigned int i;
	419	int len, sock;
	420	char buf[1024];
	421	struct sockaddr_un sunaddr;
	422
	423	for (i = 0; i < sockets_alloc; i++)
	424	switch (sockets[i].type) {
	425	case AUTH_UNUSED:
	426	break;
	427	case AUTH_SOCKET:
	428	if (FD_ISSET(sockets[i].fd, readset)) {
	429	len = sizeof(sunaddr);
	430	sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &len);
	431	if (sock < 0) {
	432	perror("accept from AUTH_SOCKET");
	433	break;
	434	}
	435	new_socket(AUTH_CONNECTION, sock);
	436	}
	437	break;
	438	case AUTH_CONNECTION:
	439	if (buffer_len(&sockets[i].output) > 0 &&
	440	FD_ISSET(sockets[i].fd, writeset)) {
	441	len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
	442	buffer_len(&sockets[i].output));
	443	if (len <= 0) {
	444	shutdown(sockets[i].fd, SHUT_RDWR);
	445	close(sockets[i].fd);
	446	sockets[i].type = AUTH_UNUSED;
	447	break;
	448	}
	449	buffer_consume(&sockets[i].output, len);
	450	}
	451	if (FD_ISSET(sockets[i].fd, readset)) {
	452	len = read(sockets[i].fd, buf, sizeof(buf));
	453	if (len <= 0) {
	454	shutdown(sockets[i].fd, SHUT_RDWR);
	455	close(sockets[i].fd);
	456	sockets[i].type = AUTH_UNUSED;
	457	break;
	458	}
	459	buffer_append(&sockets[i].input, buf, len);
	460	process_message(&sockets[i]);
	461	}
	462	break;
	463	default:
	464	fatal("Unknown type %d", sockets[i].type);
	465	}
8efc0c15	466	}
	467
	468	void
	469	check_parent_exists(int sig)
	470	{
5260325f	471	if (kill(parent_pid, 0) < 0) {
	472	/* printf("Parent has died - Authentication agent exiting.\n"); */
	473	exit(1);
	474	}
	475	signal(SIGALRM, check_parent_exists);
	476	alarm(10);
8efc0c15	477	}
8efc0c15	478
dae3fa13	479	void
	480	cleanup_socket(void)
	481	{
5260325f	482	remove(socket_name);
5260325f	483	rmdir(socket_dir);
8efc0c15	484	}
8efc0c15	485
dae3fa13	486	void
	487	cleanup_exit(int i)
	488	{
5260325f	489	cleanup_socket();
5260325f	490	exit(i);
dae3fa13	491	}
	492
	493	void
	494	usage()
	495	{
5260325f	496	fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
	497	fprintf(stderr, "Usage: %s [-c \| -s] [-k] [command {args...]]\n",
	498	__progname);
	499	exit(1);
dae3fa13	500	}
dae3fa13	501
8efc0c15	502	int
	503	main(int ac, char **av)
	504	{
5260325f	505	fd_set readset, writeset;
	506	int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
	507	struct sockaddr_un sunaddr;
	508	pid_t pid;
	509	char shell, format, pidstr, pidstrbuf[1 + 3 sizeof pid];
	510
	511	/* check if RSA support exists */
	512	if (rsa_alive() == 0) {
	513	fprintf(stderr,
	514	"%s: no RSA support in libssl and libcrypto. See ssl(8).\n",
	515	__progname);
	516	exit(1);
	517	}
5260325f	518	while ((ch = getopt(ac, av, "cks")) != -1) {
5260325f	519	switch (ch) {
	520	case 'c':
	521	if (s_flag)
	522	usage();
	523	c_flag++;
	524	break;
	525	case 'k':
	526	k_flag++;
	527	break;
	528	case 's':
	529	if (c_flag)
	530	usage();
	531	s_flag++;
	532	break;
	533	default:
	534	usage();
	535	}
dae3fa13	536	}
5260325f	537	ac -= optind;
	538	av += optind;
	539
	540	if (ac > 0 && (c_flag \|\| k_flag \|\| s_flag))
	541	usage();
	542
	543	if (ac == 0 && !c_flag && !k_flag && !s_flag) {
	544	shell = getenv("SHELL");
	545	if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
	546	c_flag = 1;
dae3fa13	547	}
5260325f	548	if (k_flag) {
	549	pidstr = getenv(SSH_AGENTPID_ENV_NAME);
	550	if (pidstr == NULL) {
	551	fprintf(stderr, "%s not set, cannot kill agent\n",
	552	SSH_AGENTPID_ENV_NAME);
	553	exit(1);
	554	}
	555	pid = atoi(pidstr);
	556	if (pid < 1) { /* XXX PID_MAX check too */
	557	fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
	558	SSH_AGENTPID_ENV_NAME, pidstr);
	559	exit(1);
	560	}
	561	if (kill(pid, SIGTERM) == -1) {
	562	perror("kill");
	563	exit(1);
	564	}
	565	format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
	566	printf(format, SSH_AUTHSOCKET_ENV_NAME);
	567	printf(format, SSH_AGENTPID_ENV_NAME);
	568	printf("echo Agent pid %d killed;\n", pid);
	569	exit(0);
dae3fa13	570	}
5260325f	571	parent_pid = getpid();
	572
	573	/* Create private directory for agent socket */
	574	strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
	575	if (mkdtemp(socket_dir) == NULL) {
	576	perror("mkdtemp: private socket dir");
	577	exit(1);
	578	}
	579	snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
	580	parent_pid);
	581
aa3378df	582	/*
	583	* Create socket early so it will exist before command gets run from
	584	* the parent.
	585	*/
5260325f	586	sock = socket(AF_UNIX, SOCK_STREAM, 0);
	587	if (sock < 0) {
	588	perror("socket");
	589	cleanup_exit(1);
	590	}
	591	memset(&sunaddr, 0, sizeof(sunaddr));
	592	sunaddr.sun_family = AF_UNIX;
	593	strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
	594	if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
	595	perror("bind");
	596	cleanup_exit(1);
	597	}
	598	if (listen(sock, 5) < 0) {
	599	perror("listen");
	600	cleanup_exit(1);
dae3fa13	601	}
aa3378df	602	/*
	603	* Fork, and have the parent execute the command, if any, or present
	604	* the socket data. The child continues as the authentication agent.
	605	*/
5260325f	606	pid = fork();
	607	if (pid == -1) {
	608	perror("fork");
	609	exit(1);
dae3fa13	610	}
5260325f	611	if (pid != 0) { /* Parent - execute the given command. */
	612	close(sock);
	613	snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
	614	if (ac == 0) {
	615	format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
	616	printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
	617	SSH_AUTHSOCKET_ENV_NAME);
	618	printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
	619	SSH_AGENTPID_ENV_NAME);
	620	printf("echo Agent pid %d;\n", pid);
	621	exit(0);
	622	}
	623	setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1);
	624	setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1);
	625	execvp(av[0], av);
	626	perror(av[0]);
	627	exit(1);
	628	}
	629	close(0);
	630	close(1);
	631	close(2);
dae3fa13	632
5260325f	633	if (setsid() == -1) {
	634	perror("setsid");
	635	cleanup_exit(1);
	636	}
	637	if (atexit(cleanup_socket) < 0) {
	638	perror("atexit");
	639	cleanup_exit(1);
	640	}
	641	new_socket(AUTH_SOCKET, sock);
	642	if (ac > 0) {
	643	signal(SIGALRM, check_parent_exists);
	644	alarm(10);
	645	}
	646	signal(SIGINT, SIG_IGN);
	647	signal(SIGPIPE, SIG_IGN);
	648	while (1) {
	649	FD_ZERO(&readset);
	650	FD_ZERO(&writeset);
	651	prepare_select(&readset, &writeset);
	652	if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
	653	if (errno == EINTR)
	654	continue;
	655	exit(1);
	656	}
	657	after_select(&readset, &writeset);
8efc0c15	658	}
5260325f	659	/* NOTREACHED */
8efc0c15	660	}