kcmd.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Copyright (c) 1983 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
/* derived from @(#)rcmd.c 5.17 (Berkeley) 6/27/88 */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <pwd.h>
#include <sys/param.h>
#include <sys/types.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <locale.h>
#include <syslog.h>
#include <errno.h>
#include <com_err.h>
#include <k5-int.h>
#include <kcmd.h>
static char *default_service = "host";
#define KCMD_BUFSIZ 102400
#define KCMD_KEYUSAGE 1026
static char storage[KCMD_BUFSIZ];
static int nstored = 0;
static int MAXSIZE = (KCMD_BUFSIZ + 8);
static char *store_ptr = storage;
static krb5_data desinbuf, desoutbuf;
static boolean_t encrypt_flag = B_FALSE;
static krb5_context kcmd_context;
/* XXX Overloaded: use_ivecs!=0 -> new protocol, inband signalling, etc. */
static boolean_t use_ivecs = B_FALSE;
static krb5_data encivec_i[2], encivec_o[2];
static krb5_keyusage enc_keyusage_i[2], enc_keyusage_o[2];
static krb5_enctype final_enctype;
static krb5_keyblock *skey;
/* ARGSUSED */
int
kcmd(int *sock, char **ahost, ushort_t rport,
char *locuser, char *remuser,
char *cmd, int *fd2p, char *service, char *realm,
krb5_context bsd_context, krb5_auth_context *authconp,
krb5_creds **cred, krb5_int32 *seqno, krb5_int32 *server_seqno,
krb5_flags authopts,
int anyport, enum kcmd_proto *protonump)
{
int s = -1;
sigset_t oldmask, urgmask;
struct sockaddr_in sin;
struct sockaddr_storage from;
krb5_creds *get_cred = NULL;
krb5_creds *ret_cred = NULL;
char c;
struct hostent *hp;
int rc;
char *host_save = NULL;
krb5_error_code status;
krb5_ap_rep_enc_part *rep_ret;
krb5_error *error = 0;
krb5_ccache cc;
krb5_data outbuf;
krb5_flags options = authopts;
krb5_auth_context auth_context = NULL;
char *cksumbuf;
krb5_data cksumdat;
int bsize = 0;
char *kcmd_version;
enum kcmd_proto protonum = *protonump;
bsize = strlen(cmd) + strlen(remuser) + 64;
if ((cksumbuf = malloc(bsize)) == 0) {
(void) fprintf(stderr, gettext("Unable to allocate"
" memory for checksum buffer.\n"));
return (-1);
}
(void) snprintf(cksumbuf, bsize, "%u:", ntohs(rport));
if (strlcat(cksumbuf, cmd, bsize) >= bsize) {
(void) fprintf(stderr, gettext("cmd buffer too long.\n"));
free(cksumbuf);
return (-1);
}
if (strlcat(cksumbuf, remuser, bsize) >= bsize) {
(void) fprintf(stderr, gettext("remuser too long.\n"));
free(cksumbuf);
return (-1);
}
cksumdat.data = cksumbuf;
cksumdat.length = strlen(cksumbuf);
hp = gethostbyname(*ahost);
if (hp == 0) {
(void) fprintf(stderr,
gettext("%s: unknown host\n"), *ahost);
return (-1);
}
if ((host_save = (char *)strdup(hp->h_name)) == NULL) {
(void) fprintf(stderr, gettext("kcmd: no memory\n"));
return (-1);
}
/* If no service is given set to the default service */
if (!service) service = default_service;
if (!(get_cred = (krb5_creds *)calloc(1, sizeof (krb5_creds)))) {
(void) fprintf(stderr, gettext("kcmd: no memory\n"));
return (-1);
}
(void) sigemptyset(&urgmask);
(void) sigaddset(&urgmask, SIGURG);
(void) sigprocmask(SIG_BLOCK, &urgmask, &oldmask);
status = krb5_sname_to_principal(bsd_context, host_save, service,
KRB5_NT_SRV_HST, &get_cred->server);
if (status) {
(void) fprintf(stderr,
gettext("kcmd: "
"krb5_sname_to_principal failed: %s\n"),
error_message(status));
status = -1;
goto bad;
}
if (realm && *realm) {
(void) krb5_xfree(
krb5_princ_realm(bsd_context, get_cred->server)->data);
krb5_princ_set_realm_length(bsd_context, get_cred->server,
strlen(realm));
krb5_princ_set_realm_data(bsd_context, get_cred->server,
strdup(realm));
}
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
perror(gettext("Error creating socket"));
status = -1;
goto bad;
}
/*
* Kerberos only supports IPv4 addresses for now.
*/
if (hp->h_addrtype == AF_INET) {
sin.sin_family = hp->h_addrtype;
(void) memcpy((void *)&sin.sin_addr,
hp->h_addr, hp->h_length);
sin.sin_port = rport;
} else {
syslog(LOG_ERR, "Address type %d not supported for "
"Kerberos", hp->h_addrtype);
status = -1;
goto bad;
}
if (connect(s, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
perror(host_save);
status = -1;
goto bad;
}
if (fd2p == 0) {
(void) write(s, "", 1);
} else {
char num[16];
int s2;
int s3;
struct sockaddr_storage sname;
struct sockaddr_in *sp;
int len = sizeof (struct sockaddr_storage);
s2 = socket(AF_INET, SOCK_STREAM, 0);
if (s2 < 0) {
status = -1;
goto bad;
}
(void) memset((char *)&sin, 0, sizeof (sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = 0;
if (bind(s2, (struct sockaddr *)&sin, sizeof (sin)) < 0) {
perror(gettext("error binding socket"));
(void) close(s2);
status = -1;
goto bad;
}
if (getsockname(s2, (struct sockaddr *)&sname, &len) < 0) {
perror(gettext("getsockname error"));
(void) close(s2);
status = -1;
goto bad;
}
sp = (struct sockaddr_in *)&sname;
(void) listen(s2, 1);
(void) snprintf(num, sizeof (num), "%d",
htons((ushort_t)sp->sin_port));
if (write(s, num, strlen(num)+1) != strlen(num)+1) {
perror(gettext("write: error setting up stderr"));
(void) close(s2);
status = -1;
goto bad;
}
s3 = accept(s2, (struct sockaddr *)&from, &len);
(void) close(s2);
if (s3 < 0) {
perror(gettext("accept"));
status = -1;
goto bad;
}
*fd2p = s3;
if (SOCK_FAMILY(from) == AF_INET) {
if (!anyport && SOCK_PORT(from) >= IPPORT_RESERVED) {
(void) fprintf(stderr,
gettext("socket: protocol "
"failure in circuit setup.\n"));
status = -1;
goto bad2;
}
} else {
(void) fprintf(stderr,
gettext("Kerberos does not support "
"address type %d\n"),
SOCK_FAMILY(from));
status = -1;
goto bad2;
}
}
if (status = krb5_cc_default(bsd_context, &cc))
goto bad2;
status = krb5_cc_get_principal(bsd_context, cc, &get_cred->client);
if (status) {
(void) krb5_cc_close(bsd_context, cc);
goto bad2;
}
/* Get ticket from credentials cache or kdc */
status = krb5_get_credentials(bsd_context, 0, cc, get_cred, &ret_cred);
(void) krb5_cc_close(bsd_context, cc);
if (status) goto bad2;
/* Reset internal flags; these should not be sent. */
authopts &= (~OPTS_FORWARD_CREDS);
authopts &= (~OPTS_FORWARDABLE_CREDS);
if ((status = krb5_auth_con_init(bsd_context, &auth_context)))
goto bad2;
if ((status = krb5_auth_con_setflags(bsd_context, auth_context,
KRB5_AUTH_CONTEXT_RET_TIME)))
goto bad2;
/* Only need local address for mk_cred() to send to krlogind */
if ((status = krb5_auth_con_genaddrs(bsd_context, auth_context, s,
KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR)))
goto bad2;
if (protonum == KCMD_PROTOCOL_COMPAT_HACK) {
krb5_boolean is_des;
status = krb5_c_enctype_compare(bsd_context,
ENCTYPE_DES_CBC_CRC,
ret_cred->keyblock.enctype,
&is_des);
if (status)
goto bad2;
protonum = is_des ? KCMD_OLD_PROTOCOL : KCMD_NEW_PROTOCOL;
}
switch (protonum) {
case KCMD_NEW_PROTOCOL:
authopts |= AP_OPTS_USE_SUBKEY;
kcmd_version = "KCMDV0.2";
break;
case KCMD_OLD_PROTOCOL:
kcmd_version = "KCMDV0.1";
break;
default:
status = -1;
goto bad2;
}
/*
* Call the Kerberos library routine to obtain an authenticator,
* pass it over the socket to the server, and obtain mutual
* authentication.
*/
status = krb5_sendauth(bsd_context, &auth_context, (krb5_pointer) &s,
kcmd_version, ret_cred->client, ret_cred->server,
authopts, &cksumdat, ret_cred, 0, &error,
&rep_ret, NULL);
krb5_xfree(cksumdat.data);
if (status) {
(void) fprintf(stderr, gettext("Couldn't authenticate"
" to server: %s\n"),
error_message(status));
if (error) {
(void) fprintf(stderr, gettext("Server returned error"
" code %d (%s)\n"),
error->error,
error_message(ERROR_TABLE_BASE_krb5 +
error->error));
if (error->text.length)
(void) fprintf(stderr,
gettext("Error text"
" sent from server: %s\n"),
error->text.data);
}
if (error) {
krb5_free_error(bsd_context, error);
error = 0;
}
goto bad2;
}
if (rep_ret && server_seqno) {
*server_seqno = rep_ret->seq_number;
krb5_free_ap_rep_enc_part(bsd_context, rep_ret);
}
(void) write(s, remuser, strlen(remuser)+1);
(void) write(s, cmd, strlen(cmd)+1);
if (locuser)
(void) write(s, locuser, strlen(locuser)+1);
else
(void) write(s, "", 1);
if (options & OPTS_FORWARD_CREDS) { /* Forward credentials */
if (status = krb5_fwd_tgt_creds(bsd_context, auth_context,
host_save,
ret_cred->client, ret_cred->server,
0, options & OPTS_FORWARDABLE_CREDS,
&outbuf)) {
(void) fprintf(stderr,
gettext("kcmd: Error getting"
" forwarded creds\n"));
goto bad2;
}
/* Send forwarded credentials */
if (status = krb5_write_message(bsd_context, (krb5_pointer)&s,
&outbuf))
goto bad2;
} else { /* Dummy write to signal no forwarding */
outbuf.length = 0;
if (status = krb5_write_message(bsd_context,
(krb5_pointer)&s, &outbuf))
goto bad2;
}
if ((rc = read(s, &c, 1)) != 1) {
if (rc == -1) {
perror(*ahost);
} else {
(void) fprintf(stderr, gettext("kcmd: bad connection "
"with remote host\n"));
}
status = -1;
goto bad2;
}
if (c != 0) {
while (read(s, &c, 1) == 1) {
(void) write(2, &c, 1);
if (c == '\n')
break;
}
status = -1;
goto bad2;
}
(void) sigprocmask(SIG_SETMASK, &oldmask, (sigset_t *)0);
*sock = s;
/* pass back credentials if wanted */
if (cred) krb5_copy_creds(bsd_context, ret_cred, cred);
krb5_free_creds(bsd_context, ret_cred);
/*
* Initialize *authconp to auth_context, so
* that the clients can make use of it
*/
*authconp = auth_context;
return (0);
bad2:
if (fd2p != NULL)
(void) close(*fd2p);
bad:
if (s > 0)
(void) close(s);
if (get_cred)
krb5_free_creds(bsd_context, get_cred);
if (ret_cred)
krb5_free_creds(bsd_context, ret_cred);
if (host_save)
free(host_save);
(void) sigprocmask(SIG_SETMASK, &oldmask, (sigset_t *)0);
return (status);
}
/*
* Strsave was a routine in the version 4 krb library: we put it here
* for compatablilty with version 5 krb library, since kcmd.o is linked
* into all programs.
*/
char *
strsave(char *sp)
{
char *ret;
if ((ret = (char *)strdup(sp)) == NULL) {
(void) fprintf(stderr, gettext("no memory for saving args\n"));
exit(1);
}
return (ret);
}
/*
* Decode, decrypt and store the forwarded creds in the local ccache.
*/
krb5_error_code
rd_and_store_for_creds(krb5_context context,
krb5_auth_context auth_context,
krb5_data *inbuf,
krb5_ticket *ticket,
char *lusername,
krb5_ccache *ccache)
{
krb5_creds ** creds;
krb5_error_code retval;
char ccname[64];
struct passwd *pwd;
uid_t uid;
*ccache = NULL;
if (!(pwd = (struct passwd *)getpwnam(lusername)))
return (ENOENT);
uid = getuid();
if (seteuid(pwd->pw_uid))
return (-1);
if ((retval =
krb5_rd_cred(context, auth_context, inbuf, &creds, NULL)) != 0)
return (retval);
(void) snprintf(ccname, sizeof (ccname),
"FILE:/tmp/krb5cc_%ld", pwd->pw_uid);
if ((retval = krb5_cc_resolve(context, ccname, ccache)) != 0)
goto cleanup;
if ((retval = krb5_cc_initialize(context, *ccache,
ticket->enc_part2->client)) != 0)
goto cleanup;
if ((retval = krb5_cc_store_cred(context, *ccache, *creds)) != 0)
goto cleanup;
if ((retval = krb5_cc_close(context, *ccache)) != 0)
goto cleanup;
cleanup:
(void) seteuid(uid);
krb5_free_creds(context, *creds);
return (retval);
}
/*
* This routine is to initialize the desinbuf, desoutbuf and the session key
* structures to carry out desread()'s and deswrite()'s successfully
*/
void
init_encrypt(int enc, krb5_context ctxt, enum kcmd_proto protonum,
krb5_data *inbuf, krb5_data *outbuf,
int amclient, krb5_encrypt_block *block)
{
krb5_error_code statuscode;
size_t blocksize;
int i;
krb5_error_code ret;
kcmd_context = ctxt;
if (enc > 0) {
desinbuf.data = inbuf->data;
desoutbuf.data = outbuf->data + 4;
desinbuf.length = inbuf->length;
desoutbuf.length = outbuf->length + 4;
encrypt_flag = B_TRUE;
} else {
encrypt_flag = B_FALSE;
return;
}
skey = block->key;
final_enctype = skey->enctype;
enc_keyusage_i[0] = KCMD_KEYUSAGE;
enc_keyusage_i[1] = KCMD_KEYUSAGE;
enc_keyusage_o[0] = KCMD_KEYUSAGE;
enc_keyusage_o[1] = KCMD_KEYUSAGE;
if (protonum == KCMD_OLD_PROTOCOL) {
use_ivecs = B_FALSE;
return;
}
use_ivecs = B_TRUE;
switch (skey->enctype) {
/*
* For the DES-based enctypes and the 3DES enctype we
* want to use a non-zero IV because that's what we did.
* In the future we use different keyusage for each
* channel and direction and a fresh cipher state.
*/
case ENCTYPE_DES_CBC_CRC:
case ENCTYPE_DES_CBC_MD4:
case ENCTYPE_DES_CBC_MD5:
case ENCTYPE_DES3_CBC_SHA1:
statuscode = krb5_c_block_size(kcmd_context, final_enctype,
&blocksize);
if (statuscode) {
/* XXX what do I do? */
abort();
}
encivec_i[0].length = encivec_i[1].length =
encivec_o[0].length = encivec_o[1].length = blocksize;
if ((encivec_i[0].data = malloc(encivec_i[0].length * 4))
== NULL) {
/* XXX what do I do? */
abort();
}
encivec_i[1].data = encivec_i[0].data + encivec_i[0].length;
encivec_o[0].data = encivec_i[1].data + encivec_i[0].length;
encivec_o[1].data = encivec_o[0].data + encivec_i[0].length;
/* is there a better way to initialize this? */
(void) memset(encivec_i[0].data, amclient, blocksize);
(void) memset(encivec_o[0].data, 1 - amclient, blocksize);
(void) memset(encivec_i[1].data, 2 | amclient, blocksize);
(void) memset(encivec_o[1].data, 2 | (1 - amclient), blocksize);
break;
default:
if (amclient) {
enc_keyusage_i[0] = 1028;
enc_keyusage_i[1] = 1030;
enc_keyusage_o[0] = 1032;
enc_keyusage_o[1] = 1034;
} else { /* amclient */
enc_keyusage_i[0] = 1032;
enc_keyusage_i[1] = 1034;
enc_keyusage_o[0] = 1028;
enc_keyusage_o[1] = 1030;
}
for (i = 0; i < 2; i++) {
ret = krb5_c_init_state(ctxt,
skey, enc_keyusage_i[i],
&encivec_i[i]);
if (ret)
goto fail;
ret = krb5_c_init_state(ctxt,
skey, enc_keyusage_o[i],
&encivec_o[i]);
if (ret)
goto fail;
}
break;
}
return;
fail:
abort();
}
int
desread(int fd, char *buf, int len, int secondary)
{
int nreturned = 0;
long net_len, rd_len;
int cc;
size_t ret = 0;
unsigned char len_buf[4];
krb5_enc_data inputd;
krb5_data outputd;
if (!encrypt_flag)
return (read(fd, buf, len));
/*
* If there is stored data from a previous read,
* put it into the output buffer and return it now.
*/
if (nstored >= len) {
(void) memcpy(buf, store_ptr, len);
store_ptr += len;
nstored -= len;
return (len);
} else if (nstored) {
(void) memcpy(buf, store_ptr, nstored);
nreturned += nstored;
buf += nstored;
len -= nstored;
nstored = 0;
}
if ((cc = krb5_net_read(kcmd_context, fd, (char *)len_buf, 4)) != 4) {
if ((cc < 0) && ((errno == EWOULDBLOCK) || (errno == EAGAIN)))
return (cc);
/* XXX can't read enough, pipe must have closed */
return (0);
}
rd_len = ((len_buf[0] << 24) | (len_buf[1] << 16) |
(len_buf[2] << 8) | len_buf[3]);
if (krb5_c_encrypt_length(kcmd_context, final_enctype,
use_ivecs ? (size_t)rd_len + 4 : (size_t)rd_len,
&ret))
net_len = ((size_t)-1);
else
net_len = ret;
if ((net_len <= 0) || (net_len > desinbuf.length)) {
/*
* preposterous length; assume out-of-sync; only recourse
* is to close connection, so return 0
*/
(void) fprintf(stderr, gettext("Read size problem.\n"));
return (0);
}
if ((cc = krb5_net_read(kcmd_context, fd, desinbuf.data, net_len))
!= net_len) {
/* pipe must have closed, return 0 */
(void) fprintf(stderr,
gettext("Read error: length received %d "
"!= expected %d.\n"),
cc, net_len);
return (0);
}
/*
* Decrypt information
*/
inputd.enctype = ENCTYPE_UNKNOWN;
inputd.ciphertext.length = net_len;
inputd.ciphertext.data = (krb5_pointer)desinbuf.data;
outputd.length = sizeof (storage);
outputd.data = (krb5_pointer)storage;
/*
* data is decrypted into the "storage" buffer, which
* had better be large enough!
*/
cc = krb5_c_decrypt(kcmd_context, skey,
enc_keyusage_i[secondary],
use_ivecs ? encivec_i + secondary : 0,
&inputd, &outputd);
if (cc) {
(void) fprintf(stderr, gettext("Cannot decrypt data "
"from network\n"));
return (0);
}
store_ptr = storage;
nstored = rd_len;
if (use_ivecs == B_TRUE) {
int rd_len2;
rd_len2 = storage[0] & 0xff;
rd_len2 <<= 8; rd_len2 |= storage[1] & 0xff;
rd_len2 <<= 8; rd_len2 |= storage[2] & 0xff;
rd_len2 <<= 8; rd_len2 |= storage[3] & 0xff;
if (rd_len2 != rd_len) {
/* cleartext length trashed? */
errno = EIO;
return (-1);
}
store_ptr += 4;
}
/*
* Copy only as much data as the input buffer will allow.
* The rest is kept in the 'storage' pointer for the next
* read.
*/
if (nstored > len) {
(void) memcpy(buf, store_ptr, len);
nreturned += len;
store_ptr += len;
nstored -= len;
} else {
(void) memcpy(buf, store_ptr, nstored);
nreturned += nstored;
nstored = 0;
}
return (nreturned);
}
int
deswrite(int fd, char *buf, int len, int secondary)
{
int cc;
size_t ret = 0;
krb5_data inputd;
krb5_enc_data outputd;
char tmpbuf[KCMD_BUFSIZ + 8];
char encrbuf[KCMD_BUFSIZ + 8];
unsigned char *len_buf = (unsigned char *)tmpbuf;
if (!encrypt_flag)
return (write(fd, buf, len));
if (use_ivecs == B_TRUE) {
unsigned char *lenbuf2 = (unsigned char *)tmpbuf;
if (len + 4 > sizeof (tmpbuf))
abort();
lenbuf2[0] = (len & 0xff000000) >> 24;
lenbuf2[1] = (len & 0xff0000) >> 16;
lenbuf2[2] = (len & 0xff00) >> 8;
lenbuf2[3] = (len & 0xff);
(void) memcpy(tmpbuf + 4, buf, len);
inputd.data = (krb5_pointer)tmpbuf;
inputd.length = len + 4;
} else {
inputd.data = (krb5_pointer)buf;
inputd.length = len;
}
desoutbuf.data = encrbuf;
if (krb5_c_encrypt_length(kcmd_context, final_enctype,
use_ivecs ? (size_t)len + 4 : (size_t)len, &ret)) {
desoutbuf.length = ((size_t)-1);
goto err;
} else {
desoutbuf.length = ret;
}
if (desoutbuf.length > MAXSIZE) {
(void) fprintf(stderr, gettext("Write size problem.\n"));
return (-1);
}
/*
* Encrypt information
*/
outputd.ciphertext.length = desoutbuf.length;
outputd.ciphertext.data = (krb5_pointer)desoutbuf.data;
cc = krb5_c_encrypt(kcmd_context, skey,
enc_keyusage_o[secondary],
use_ivecs ? encivec_o + secondary : 0,
&inputd, &outputd);
if (cc) {
err:
(void) fprintf(stderr, gettext("Write encrypt problem.\n"));
return (-1);
}
len_buf[0] = (len & 0xff000000) >> 24;
len_buf[1] = (len & 0xff0000) >> 16;
len_buf[2] = (len & 0xff00) >> 8;
len_buf[3] = (len & 0xff);
(void) write(fd, len_buf, 4);
if (write(fd, desoutbuf.data, desoutbuf.length) != desoutbuf.length) {
(void) fprintf(stderr, gettext("Could not write "
"out all data.\n"));
return (-1);
} else {
return (len);
}
}