[openssh.git] / ssh-agent.c

/*	$OpenBSD: ssh-agent.c,v 1.31 2000/04/29 18:11:52 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 1.31 2000/04/29 18:11:52 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"

#include <openssl/md5.h>

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 */
pid_t 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 */
static 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))
		log("Warning: identity 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;
	socklen_t slen;
	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)) {
				slen = sizeof(sunaddr);
				sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
				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;
					buffer_free(&sockets[i].input);
					buffer_free(&sockets[i].output);
					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;
					buffer_free(&sockets[i].input);
					buffer_free(&sockets[i].output);
					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 (parent_pid != -1 && 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);
	}
#ifdef __GNU_LIBRARY__
	while ((ch = getopt(ac, av, "+cks")) != -1) {
#else /* __GNU_LIBRARY__ */
	while ((ch = getopt(ac, av, "cks")) != -1) {
#endif /* __GNU_LIBRARY__ */
		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 */
		/* Yes, PID_MAX check please */
			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);
	signal(SIGHUP, cleanup_exit);
	signal(SIGTERM, cleanup_exit);
	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
0b242b12	1	/* $OpenBSD: ssh-agent.c,v 1.31 2000/04/29 18:11:52 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"
0b242b12	12	RCSID("$OpenBSD: ssh-agent.c,v 1.31 2000/04/29 18:11:52 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
	24	#include <openssl/md5.h>
	25
5260325f	26	typedef struct {
	27	int fd;
	28	enum {
	29	AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
	30	} type;
	31	Buffer input;
	32	Buffer output;
8efc0c15	33	} SocketEntry;
	34
	35	unsigned int sockets_alloc = 0;
	36	SocketEntry *sockets = NULL;
	37
5260325f	38	typedef struct {
	39	RSA *key;
	40	char *comment;
8efc0c15	41	} Identity;
	42
	43	unsigned int num_identities = 0;
	44	Identity *identities = NULL;
	45
	46	int max_fd = 0;
	47
	48	/* pid of shell == parent of agent */
9da5c3c9	49	pid_t parent_pid = -1;
8efc0c15	50
	51	/* pathname and directory for AUTH_SOCKET */
	52	char socket_name[1024];
	53	char socket_dir[1024];
	54
5260325f	55	#ifdef HAVE___PROGNAME
	56	extern char *__progname;
	57	#else /* HAVE___PROGNAME */
3fd95d9a	58	static const char *__progname = "ssh-agent";
5260325f	59	#endif /* HAVE___PROGNAME */
5260325f	60
8efc0c15	61	void
	62	process_request_identity(SocketEntry *e)
	63	{
5260325f	64	Buffer msg;
	65	int i;
	66
	67	buffer_init(&msg);
	68	buffer_put_char(&msg, SSH_AGENT_RSA_IDENTITIES_ANSWER);
	69	buffer_put_int(&msg, num_identities);
	70	for (i = 0; i < num_identities; i++) {
	71	buffer_put_int(&msg, BN_num_bits(identities[i].key->n));
	72	buffer_put_bignum(&msg, identities[i].key->e);
	73	buffer_put_bignum(&msg, identities[i].key->n);
	74	buffer_put_string(&msg, identities[i].comment,
	75	strlen(identities[i].comment));
	76	}
	77	buffer_put_int(&e->output, buffer_len(&msg));
	78	buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
	79	buffer_free(&msg);
8efc0c15	80	}
	81
	82	void
	83	process_authentication_challenge(SocketEntry *e)
	84	{
5260325f	85	int i, pub_bits, len;
	86	BIGNUM pub_e, pub_n, *challenge;
	87	Buffer msg;
	88	MD5_CTX md;
	89	unsigned char buf[32], mdbuf[16], session_id[16];
	90	unsigned int response_type;
	91
	92	buffer_init(&msg);
	93	pub_e = BN_new();
	94	pub_n = BN_new();
	95	challenge = BN_new();
	96	pub_bits = buffer_get_int(&e->input);
	97	buffer_get_bignum(&e->input, pub_e);
	98	buffer_get_bignum(&e->input, pub_n);
	99	buffer_get_bignum(&e->input, challenge);
	100	if (buffer_len(&e->input) == 0) {
	101	/* Compatibility code for old servers. */
	102	memset(session_id, 0, 16);
	103	response_type = 0;
	104	} else {
	105	/* New code. */
	106	buffer_get(&e->input, (char *) session_id, 16);
	107	response_type = buffer_get_int(&e->input);
	108	}
	109	for (i = 0; i < num_identities; i++)
	110	if (pub_bits == BN_num_bits(identities[i].key->n) &&
	111	BN_cmp(pub_e, identities[i].key->e) == 0 &&
	112	BN_cmp(pub_n, identities[i].key->n) == 0) {
	113	/* Decrypt the challenge using the private key. */
	114	rsa_private_decrypt(challenge, challenge, identities[i].key);
	115
	116	/* Compute the desired response. */
	117	switch (response_type) {
	118	case 0:/* As of protocol 1.0 */
	119	/* This response type is no longer supported. */
	120	log("Compatibility with ssh protocol 1.0 no longer supported.");
	121	buffer_put_char(&msg, SSH_AGENT_FAILURE);
	122	goto send;
	123
	124	case 1:/* As of protocol 1.1 */
	125	/* The response is MD5 of decrypted challenge plus session id. */
	126	len = BN_num_bytes(challenge);
	127
	128	if (len <= 0 \|\| len > 32) {
	129	fatal("process_authentication_challenge: "
	130	"bad challenge length %d", len);
	131	}
	132	memset(buf, 0, 32);
	133	BN_bn2bin(challenge, buf + 32 - len);
	134	MD5_Init(&md);
	135	MD5_Update(&md, buf, 32);
	136	MD5_Update(&md, session_id, 16);
	137	MD5_Final(mdbuf, &md);
	138	break;
	139
	140	default:
	141	fatal("process_authentication_challenge: bad response_type %d",
	142	response_type);
	143	break;
	144	}
	145
	146	/* Send the response. */
	147	buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
	148	for (i = 0; i < 16; i++)
149	buffer_put_char(&msg, mdbuf[i]);
150
151	goto send;
152	}
153	/* Unknown identity. Send failure. */
154	buffer_put_char(&msg, SSH_AGENT_FAILURE);
155	send:
156	buffer_put_int(&e->output, buffer_len(&msg));
157	buffer_append(&e->output, buffer_ptr(&msg),
158	buffer_len(&msg));
159	buffer_free(&msg);
160	BN_clear_free(pub_e);
161	BN_clear_free(pub_n);
162	BN_clear_free(challenge);
8efc0c15	163	}
	164
	165	void
	166	process_remove_identity(SocketEntry *e)
	167	{
5260325f	168	unsigned int bits;
	169	unsigned int i;
	170	BIGNUM dummy, n;
	171
	172	dummy = BN_new();
	173	n = BN_new();
	174
	175	/* Get the key from the packet. */
	176	bits = buffer_get_int(&e->input);
	177	buffer_get_bignum(&e->input, dummy);
	178	buffer_get_bignum(&e->input, n);
	179
	180	if (bits != BN_num_bits(n))
0b242b12	181	log("Warning: identity keysize mismatch: actual %d, announced %d",
5260325f	182	BN_num_bits(n), bits);
	183
	184	/* Check if we have the key. */
	185	for (i = 0; i < num_identities; i++)
	186	if (BN_cmp(identities[i].key->n, n) == 0) {
aa3378df	187	/*
	188	* We have this key. Free the old key. Since we
	189	* don\'t want to leave empty slots in the middle of
	190	* the array, we actually free the key there and copy
	191	* data from the last entry.
	192	*/
5260325f	193	RSA_free(identities[i].key);
	194	xfree(identities[i].comment);
	195	if (i < num_identities - 1)
	196	identities[i] = identities[num_identities - 1];
	197	num_identities--;
	198	BN_clear_free(dummy);
	199	BN_clear_free(n);
	200
	201	/* Send success. */
	202	buffer_put_int(&e->output, 1);
	203	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	204	return;
	205	}
	206	/* We did not have the key. */
	207	BN_clear(dummy);
	208	BN_clear(n);
	209
	210	/* Send failure. */
8efc0c15	211	buffer_put_int(&e->output, 1);
5260325f	212	buffer_put_char(&e->output, SSH_AGENT_FAILURE);
8efc0c15	213	}
8efc0c15	214
5260325f	215	/*
	216	* Removes all identities from the agent.
	217	*/
8efc0c15	218	void
	219	process_remove_all_identities(SocketEntry *e)
	220	{
5260325f	221	unsigned int i;
8efc0c15	222
5260325f	223	/* Loop over all identities and clear the keys. */
	224	for (i = 0; i < num_identities; i++) {
	225	RSA_free(identities[i].key);
	226	xfree(identities[i].comment);
	227	}
8efc0c15	228
5260325f	229	/* Mark that there are no identities. */
5260325f	230	num_identities = 0;
8efc0c15	231
	232	/* Send success. */
	233	buffer_put_int(&e->output, 1);
	234	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	235	return;
5260325f	236	}
	237
	238	/*
	239	* Adds an identity to the agent.
	240	*/
	241	void
	242	process_add_identity(SocketEntry *e)
	243	{
	244	RSA *k;
	245	int i;
	246	BIGNUM *aux;
	247	BN_CTX *ctx;
	248
	249	if (num_identities == 0)
	250	identities = xmalloc(sizeof(Identity));
	251	else
	252	identities = xrealloc(identities, (num_identities + 1) * sizeof(Identity));
	253
	254	identities[num_identities].key = RSA_new();
	255	k = identities[num_identities].key;
	256	buffer_get_int(&e->input); /* bits */
	257	k->n = BN_new();
	258	buffer_get_bignum(&e->input, k->n);
	259	k->e = BN_new();
	260	buffer_get_bignum(&e->input, k->e);
	261	k->d = BN_new();
	262	buffer_get_bignum(&e->input, k->d);
	263	k->iqmp = BN_new();
	264	buffer_get_bignum(&e->input, k->iqmp);
	265	/* SSH and SSL have p and q swapped */
	266	k->q = BN_new();
	267	buffer_get_bignum(&e->input, k->q); /* p */
	268	k->p = BN_new();
	269	buffer_get_bignum(&e->input, k->p); /* q */
	270
	271	/* Generate additional parameters */
	272	aux = BN_new();
	273	ctx = BN_CTX_new();
	274
	275	BN_sub(aux, k->q, BN_value_one());
	276	k->dmq1 = BN_new();
	277	BN_mod(k->dmq1, k->d, aux, ctx);
	278
	279	BN_sub(aux, k->p, BN_value_one());
	280	k->dmp1 = BN_new();
	281	BN_mod(k->dmp1, k->d, aux, ctx);
	282
	283	BN_clear_free(aux);
	284	BN_CTX_free(ctx);
	285
	286	identities[num_identities].comment = buffer_get_string(&e->input, NULL);
	287
	288	/* Check if we already have the key. */
	289	for (i = 0; i < num_identities; i++)
	290	if (BN_cmp(identities[i].key->n, k->n) == 0) {
aa3378df	291	/*
	292	* We already have this key. Clear and free the new
	293	* data and return success.
	294	*/
5260325f	295	RSA_free(k);
	296	xfree(identities[num_identities].comment);
	297
	298	/* Send success. */
	299	buffer_put_int(&e->output, 1);
	300	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
	301	return;
	302	}
	303	/* Increment the number of identities. */
	304	num_identities++;
	305
	306	/* Send a success message. */
	307	buffer_put_int(&e->output, 1);
	308	buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
8efc0c15	309	}
	310
	311	void
	312	process_message(SocketEntry *e)
	313	{
5260325f	314	unsigned int msg_len;
	315	unsigned int type;
	316	unsigned char *cp;
	317	if (buffer_len(&e->input) < 5)
	318	return; /* Incomplete message. */
	319	cp = (unsigned char *) buffer_ptr(&e->input);
	320	msg_len = GET_32BIT(cp);
	321	if (msg_len > 256 * 1024) {
	322	shutdown(e->fd, SHUT_RDWR);
	323	close(e->fd);
	324	e->type = AUTH_UNUSED;
	325	return;
	326	}
	327	if (buffer_len(&e->input) < msg_len + 4)
	328	return;
	329	buffer_consume(&e->input, 4);
	330	type = buffer_get_char(&e->input);
	331
	332	switch (type) {
	333	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
	334	process_request_identity(e);
	335	break;
	336	case SSH_AGENTC_RSA_CHALLENGE:
	337	process_authentication_challenge(e);
	338	break;
	339	case SSH_AGENTC_ADD_RSA_IDENTITY:
	340	process_add_identity(e);
	341	break;
	342	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
	343	process_remove_identity(e);
	344	break;
	345	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
	346	process_remove_all_identities(e);
	347	break;
	348	default:
	349	/* Unknown message. Respond with failure. */
	350	error("Unknown message %d", type);
	351	buffer_clear(&e->input);
	352	buffer_put_int(&e->output, 1);
	353	buffer_put_char(&e->output, SSH_AGENT_FAILURE);
	354	break;
	355	}
8efc0c15	356	}
	357
	358	void
	359	new_socket(int type, int fd)
	360	{
5260325f	361	unsigned int i, old_alloc;
	362	if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
	363	error("fcntl O_NONBLOCK: %s", strerror(errno));
	364
	365	if (fd > max_fd)
	366	max_fd = fd;
	367
	368	for (i = 0; i < sockets_alloc; i++)
	369	if (sockets[i].type == AUTH_UNUSED) {
	370	sockets[i].fd = fd;
	371	sockets[i].type = type;
	372	buffer_init(&sockets[i].input);
	373	buffer_init(&sockets[i].output);
	374	return;
	375	}
	376	old_alloc = sockets_alloc;
	377	sockets_alloc += 10;
	378	if (sockets)
	379	sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
	380	else
	381	sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
	382	for (i = old_alloc; i < sockets_alloc; i++)
	383	sockets[i].type = AUTH_UNUSED;
	384	sockets[old_alloc].type = type;
	385	sockets[old_alloc].fd = fd;
	386	buffer_init(&sockets[old_alloc].input);
	387	buffer_init(&sockets[old_alloc].output);
8efc0c15	388	}
	389
	390	void
	391	prepare_select(fd_set readset, fd_set writeset)
	392	{
5260325f	393	unsigned int i;
	394	for (i = 0; i < sockets_alloc; i++)
	395	switch (sockets[i].type) {
	396	case AUTH_SOCKET:
	397	case AUTH_CONNECTION:
	398	FD_SET(sockets[i].fd, readset);
	399	if (buffer_len(&sockets[i].output) > 0)
	400	FD_SET(sockets[i].fd, writeset);
	401	break;
	402	case AUTH_UNUSED:
	403	break;
	404	default:
	405	fatal("Unknown socket type %d", sockets[i].type);
	406	break;
	407	}
8efc0c15	408	}
8efc0c15	409
6ae2364d	410	void
5260325f	411	after_select(fd_set readset, fd_set writeset)
8efc0c15	412	{
5260325f	413	unsigned int i;
5260325f	414	int len, sock;
610cd5c6	415	socklen_t slen;
5260325f	416	char buf[1024];
	417	struct sockaddr_un sunaddr;
	418
	419	for (i = 0; i < sockets_alloc; i++)
	420	switch (sockets[i].type) {
	421	case AUTH_UNUSED:
	422	break;
	423	case AUTH_SOCKET:
	424	if (FD_ISSET(sockets[i].fd, readset)) {
610cd5c6	425	slen = sizeof(sunaddr);
610cd5c6	426	sock = accept(sockets[i].fd, (struct sockaddr *) & sunaddr, &slen);
5260325f	427	if (sock < 0) {
	428	perror("accept from AUTH_SOCKET");
	429	break;
	430	}
	431	new_socket(AUTH_CONNECTION, sock);
	432	}
	433	break;
	434	case AUTH_CONNECTION:
	435	if (buffer_len(&sockets[i].output) > 0 &&
	436	FD_ISSET(sockets[i].fd, writeset)) {
	437	len = write(sockets[i].fd, buffer_ptr(&sockets[i].output),
	438	buffer_len(&sockets[i].output));
	439	if (len <= 0) {
	440	shutdown(sockets[i].fd, SHUT_RDWR);
	441	close(sockets[i].fd);
	442	sockets[i].type = AUTH_UNUSED;
0ac7199f	443	buffer_free(&sockets[i].input);
0ac7199f	444	buffer_free(&sockets[i].output);
5260325f	445	break;
	446	}
	447	buffer_consume(&sockets[i].output, len);
	448	}
	449	if (FD_ISSET(sockets[i].fd, readset)) {
	450	len = read(sockets[i].fd, buf, sizeof(buf));
	451	if (len <= 0) {
	452	shutdown(sockets[i].fd, SHUT_RDWR);
	453	close(sockets[i].fd);
	454	sockets[i].type = AUTH_UNUSED;
0ac7199f	455	buffer_free(&sockets[i].input);
0ac7199f	456	buffer_free(&sockets[i].output);
5260325f	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	{
9da5c3c9	471	if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
5260325f	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	}
4e577b89	518	#ifdef __GNU_LIBRARY__
	519	while ((ch = getopt(ac, av, "+cks")) != -1) {
	520	#else /* __GNU_LIBRARY__ */
5260325f	521	while ((ch = getopt(ac, av, "cks")) != -1) {
4e577b89	522	#endif /* __GNU_LIBRARY__ */
5260325f	523	switch (ch) {
	524	case 'c':
	525	if (s_flag)
	526	usage();
	527	c_flag++;
	528	break;
	529	case 'k':
	530	k_flag++;
	531	break;
	532	case 's':
	533	if (c_flag)
	534	usage();
	535	s_flag++;
	536	break;
	537	default:
	538	usage();
	539	}
dae3fa13	540	}
5260325f	541	ac -= optind;
	542	av += optind;
	543
	544	if (ac > 0 && (c_flag \|\| k_flag \|\| s_flag))
	545	usage();
	546
	547	if (ac == 0 && !c_flag && !k_flag && !s_flag) {
	548	shell = getenv("SHELL");
	549	if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
	550	c_flag = 1;
dae3fa13	551	}
5260325f	552	if (k_flag) {
	553	pidstr = getenv(SSH_AGENTPID_ENV_NAME);
	554	if (pidstr == NULL) {
	555	fprintf(stderr, "%s not set, cannot kill agent\n",
	556	SSH_AGENTPID_ENV_NAME);
	557	exit(1);
	558	}
	559	pid = atoi(pidstr);
	560	if (pid < 1) { /* XXX PID_MAX check too */
9da5c3c9	561	/* Yes, PID_MAX check please */
5260325f	562	fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
	563	SSH_AGENTPID_ENV_NAME, pidstr);
	564	exit(1);
	565	}
	566	if (kill(pid, SIGTERM) == -1) {
	567	perror("kill");
	568	exit(1);
	569	}
	570	format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
	571	printf(format, SSH_AUTHSOCKET_ENV_NAME);
	572	printf(format, SSH_AGENTPID_ENV_NAME);
	573	printf("echo Agent pid %d killed;\n", pid);
	574	exit(0);
dae3fa13	575	}
5260325f	576	parent_pid = getpid();
	577
	578	/* Create private directory for agent socket */
	579	strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
	580	if (mkdtemp(socket_dir) == NULL) {
	581	perror("mkdtemp: private socket dir");
	582	exit(1);
	583	}
	584	snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
	585	parent_pid);
	586
aa3378df	587	/*
	588	* Create socket early so it will exist before command gets run from
	589	* the parent.
	590	*/
5260325f	591	sock = socket(AF_UNIX, SOCK_STREAM, 0);
	592	if (sock < 0) {
	593	perror("socket");
	594	cleanup_exit(1);
	595	}
	596	memset(&sunaddr, 0, sizeof(sunaddr));
	597	sunaddr.sun_family = AF_UNIX;
	598	strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
	599	if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
	600	perror("bind");
	601	cleanup_exit(1);
	602	}
	603	if (listen(sock, 5) < 0) {
	604	perror("listen");
	605	cleanup_exit(1);
dae3fa13	606	}
aa3378df	607	/*
	608	* Fork, and have the parent execute the command, if any, or present
	609	* the socket data. The child continues as the authentication agent.
	610	*/
5260325f	611	pid = fork();
	612	if (pid == -1) {
	613	perror("fork");
	614	exit(1);
dae3fa13	615	}
5260325f	616	if (pid != 0) { /* Parent - execute the given command. */
	617	close(sock);
	618	snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
	619	if (ac == 0) {
	620	format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
	621	printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
	622	SSH_AUTHSOCKET_ENV_NAME);
	623	printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
	624	SSH_AGENTPID_ENV_NAME);
	625	printf("echo Agent pid %d;\n", pid);
	626	exit(0);
	627	}
	628	setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1);
	629	setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1);
	630	execvp(av[0], av);
	631	perror(av[0]);
	632	exit(1);
	633	}
	634	close(0);
	635	close(1);
	636	close(2);
dae3fa13	637
5260325f	638	if (setsid() == -1) {
	639	perror("setsid");
	640	cleanup_exit(1);
	641	}
	642	if (atexit(cleanup_socket) < 0) {
	643	perror("atexit");
	644	cleanup_exit(1);
	645	}
	646	new_socket(AUTH_SOCKET, sock);
	647	if (ac > 0) {
	648	signal(SIGALRM, check_parent_exists);
	649	alarm(10);
	650	}
	651	signal(SIGINT, SIG_IGN);
	652	signal(SIGPIPE, SIG_IGN);
6ae2364d	653	signal(SIGHUP, cleanup_exit);
6ae2364d	654	signal(SIGTERM, cleanup_exit);
5260325f	655	while (1) {
	656	FD_ZERO(&readset);
	657	FD_ZERO(&writeset);
	658	prepare_select(&readset, &writeset);
	659	if (select(max_fd + 1, &readset, &writeset, NULL, NULL) < 0) {
	660	if (errno == EINTR)
	661	continue;
	662	exit(1);
	663	}
	664	after_select(&readset, &writeset);
8efc0c15	665	}
5260325f	666	/* NOTREACHED */
8efc0c15	667	}