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cifs.upcall.c
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cifs.upcall.c
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/*
* CIFS user-space helper.
* Copyright (C) Igor Mammedov ([email protected]) 2007
* Copyright (C) Jeff Layton ([email protected]) 2010
*
* Used by /sbin/request-key for handling
* cifs upcall for kerberos authorization of access to share and
* cifs upcall for DFS srver name resolving (IPv4/IPv6 aware).
* You should have keyutils installed and add something like the
* following lines to /etc/request-key.conf file:
create cifs.spnego * * /usr/local/sbin/cifs.upcall %k
create dns_resolver * * /usr/local/sbin/cifs.upcall %k
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#include <string.h>
#include <getopt.h>
#ifdef HAVE_KRB5_KRB5_H
#include <krb5/krb5.h>
#elif defined(HAVE_KRB5_H)
#include <krb5.h>
#endif
#include <gssapi/gssapi_krb5.h>
#include <sys/utsname.h>
#include <syslog.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <keyutils.h>
#include <time.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <pwd.h>
#include <grp.h>
#include <stdbool.h>
#include <errno.h>
#include <sched.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "data_blob.h"
#include "spnego.h"
#include "cifs_spnego.h"
#ifdef HAVE_LIBCAP_NG
#include <cap-ng.h>
#endif
#ifndef discard_const
#define discard_const(ptr) ((void *)((intptr_t)(ptr)))
#endif
static krb5_context context;
static const char *prog = "cifs.upcall";
#define DNS_RESOLVER_DEFAULT_TIMEOUT 600 /* 10 minutes */
typedef enum _sectype {
NONE = 0,
KRB5,
MS_KRB5
} sectype_t;
/* These macros unify the keyblock handling of Heimdal and MIT somewhat */
#ifdef HAVE_KRB5_KEYBLOCK_KEYVALUE /* Heimdal */
#define KRB5_KEY_TYPE(k) ((k)->keytype)
#define KRB5_KEY_LENGTH(k) ((k)->keyvalue.length)
#define KRB5_KEY_DATA(k) ((k)->keyvalue.data)
#define KRB5_KEY_DATA_CAST void
#else /* MIT */
#define KRB5_KEY_TYPE(k) ((k)->enctype)
#define KRB5_KEY_LENGTH(k) ((k)->length)
#define KRB5_KEY_DATA(k) ((k)->contents)
#define KRB5_KEY_DATA_CAST krb5_octet
#endif
#ifdef HAVE_LIBCAP_NG
static int
trim_capabilities(bool need_environ)
{
capng_select_t set = CAPNG_SELECT_CAPS;
capng_clear(CAPNG_SELECT_BOTH);
/* SETUID and SETGID to change uid, gid, and grouplist */
if (capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,
CAP_SETUID, CAP_SETGID, -1)) {
syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);
return 1;
}
/* Need PTRACE and READ_SEARCH for /proc/pid/environ scraping */
if (need_environ &&
capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,
CAP_SYS_PTRACE, CAP_DAC_READ_SEARCH, -1)) {
syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);
return 1;
}
if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP)) {
set = CAPNG_SELECT_BOTH;
}
if (capng_apply(set)) {
syslog(LOG_ERR, "%s: Unable to apply capability set: %m\n", __func__);
return 1;
}
return 0;
}
static int
drop_all_capabilities(void)
{
capng_select_t set = CAPNG_SELECT_CAPS;
capng_clear(CAPNG_SELECT_BOTH);
if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP)) {
set = CAPNG_SELECT_BOTH;
}
if (capng_apply(set)) {
syslog(LOG_ERR, "%s: Unable to apply capability set: %m\n", __func__);
return 1;
}
return 0;
}
#else /* HAVE_LIBCAP_NG */
static int
trim_capabilities(bool unused)
{
(void)unused;
return 0;
}
static int
drop_all_capabilities(void)
{
return 0;
}
#endif /* HAVE_LIBCAP_NG */
/*
* smb_krb5_principal_get_realm
*
* @brief Get realm of a principal
*
* @param[in] context The krb5_context
* @param[in] principal The principal
* @return pointer to the realm
*
*/
static char *cifs_krb5_principal_get_realm(krb5_principal principal)
{
#ifdef HAVE_KRB5_PRINCIPAL_GET_REALM /* Heimdal */
return krb5_principal_get_realm(context, principal);
#elif defined(krb5_princ_realm) /* MIT */
krb5_data *realm;
realm = krb5_princ_realm(context, principal);
return (char *)realm->data;
#else
return NULL;
#endif
}
#if !defined(HAVE_KRB5_FREE_UNPARSED_NAME)
static void krb5_free_unparsed_name(krb5_context context, char *val)
{
free(val);
}
#endif
#if !defined(HAVE_KRB5_FREE_STRING) /* Heimdal */
static void krb5_free_string(krb5_context context, char *val)
{
(void)context;
krb5_xfree(val);
}
#endif
#if !defined(HAVE_KRB5_AUTH_CON_GETSENDSUBKEY) /* Heimdal */
static krb5_error_code
krb5_auth_con_getsendsubkey(krb5_context context,
krb5_auth_context auth_context,
krb5_keyblock **keyblock)
{
return krb5_auth_con_getlocalsubkey(context, auth_context, keyblock);
}
#endif
/* does the ccache have a valid TGT? */
static time_t get_tgt_time(krb5_ccache ccache)
{
krb5_cc_cursor cur;
krb5_creds creds;
krb5_principal principal;
time_t credtime = 0;
char *realm = NULL;
if (krb5_cc_set_flags(context, ccache, 0)) {
syslog(LOG_DEBUG, "%s: unable to set flags", __func__);
goto err_cache;
}
if (krb5_cc_get_principal(context, ccache, &principal)) {
syslog(LOG_DEBUG, "%s: unable to get principal", __func__);
goto err_cache;
}
if (krb5_cc_start_seq_get(context, ccache, &cur)) {
syslog(LOG_DEBUG, "%s: unable to seq start", __func__);
goto err_ccstart;
}
if ((realm = cifs_krb5_principal_get_realm(principal)) == NULL) {
syslog(LOG_DEBUG, "%s: unable to get realm", __func__);
goto err_ccstart;
}
while (!credtime && !krb5_cc_next_cred(context, ccache, &cur, &creds)) {
char *name;
if (krb5_unparse_name(context, creds.server, &name)) {
syslog(LOG_DEBUG, "%s: unable to unparse name",
__func__);
goto err_endseq;
}
if (krb5_realm_compare(context, creds.server, principal) &&
!strncasecmp(name, KRB5_TGS_NAME, KRB5_TGS_NAME_SIZE) &&
!strncasecmp(name + KRB5_TGS_NAME_SIZE + 1, realm,
strlen(realm))
&& creds.times.endtime > time(NULL))
credtime = creds.times.endtime;
krb5_free_cred_contents(context, &creds);
krb5_free_unparsed_name(context, name);
}
err_endseq:
krb5_cc_end_seq_get(context, ccache, &cur);
err_ccstart:
krb5_free_principal(context, principal);
err_cache:
return credtime;
}
static struct namespace_file {
int nstype;
const char *name;
int fd;
} namespace_files[] = {
#ifdef CLONE_NEWCGROUP
{ CLONE_NEWCGROUP, "cgroup", -1 },
#endif
#ifdef CLONE_NEWIPC
{ CLONE_NEWIPC, "ipc", -1 },
#endif
#ifdef CLONE_NEWUTS
{ CLONE_NEWUTS, "uts", -1 },
#endif
#ifdef CLONE_NEWNET
{ CLONE_NEWNET, "net", -1 },
#endif
#ifdef CLONE_NEWPID
{ CLONE_NEWPID, "pid", -1 },
#endif
#ifdef CLONE_NEWTIME
{ CLONE_NEWTIME, "time", -1 },
#endif
#ifdef CLONE_NEWNS
{ CLONE_NEWNS, "mnt", -1 },
#endif
#ifdef CLONE_NEWUSER
{ CLONE_NEWUSER, "user", -1 },
#endif
};
#define NS_PATH_FMT "/proc/%d/ns/%s"
#define NS_PATH_MAXLEN (6 + 10 + 4 + 6 + 1)
/**
* in_same_user_ns - return true if two processes are in the same user
* namespace.
* @pid_a: the pid of the first process
* @pid_b: the pid of the second process
*
* Works by comparing the inode numbers for /proc/<pid>/user.
*/
static int
in_same_user_ns(pid_t pid_a, pid_t pid_b)
{
char path[NS_PATH_MAXLEN];
ino_t a_ino, b_ino;
struct stat st;
snprintf(path, sizeof(path), NS_PATH_FMT, pid_a, "user");
if (stat(path, &st) != 0)
return 0;
a_ino = st.st_ino;
snprintf(path, sizeof(path), NS_PATH_FMT, pid_b, "user");
if (stat(path, &st) != 0)
return 0;
b_ino = st.st_ino;
return a_ino == b_ino;
}
/**
* switch_to_process_ns - change the namespace to the one for the specified
* process.
* @pid: initiating pid value from the upcall string
*
* Uses setns() to switch process namespace.
* This ensures that we have the same access and configuration as the
* process that triggered the lookup.
*/
static int
switch_to_process_ns(pid_t pid)
{
int count = sizeof(namespace_files) / sizeof(struct namespace_file);
int n, err = 0;
int rc = 0;
/* First, open all the namespace fds. We do this first because
the namespace changes might prohibit us from opening them. */
for (n = 0; n < count; ++n) {
char nspath[NS_PATH_MAXLEN];
int ret, fd;
#ifdef CLONE_NEWUSER
if (namespace_files[n].nstype == CLONE_NEWUSER
&& in_same_user_ns(getpid(), pid)) {
/* Switching to the same user namespace is forbidden,
because switching to a user namespace grants all
capabilities in that namespace regardless of uid. */
namespace_files[n].fd = -1;
continue;
}
#endif
ret = snprintf(nspath, NS_PATH_MAXLEN, NS_PATH_FMT,
pid, namespace_files[n].name);
if (ret >= NS_PATH_MAXLEN) {
syslog(LOG_DEBUG, "%s: unterminated path!\n", __func__);
err = ENAMETOOLONG;
rc = -1;
goto out;
}
fd = open(nspath, O_RDONLY);
if (fd < 0 && errno != ENOENT) {
/*
* don't stop on non-existing ns
* but stop for other errors
*/
err = errno;
rc = -1;
goto out;
}
namespace_files[n].fd = fd;
}
/* Next, call setns for each of them */
for (n = 0; n < count; ++n) {
/* skip non-existing ns */
if (namespace_files[n].fd < 0)
continue;
rc = setns(namespace_files[n].fd, namespace_files[n].nstype);
if (rc < 0) {
syslog(LOG_DEBUG, "%s: setns() failed for %s\n",
__func__, namespace_files[n].name);
err = errno;
goto out;
}
}
out:
/* Finally, close all the fds */
for (n = 0; n < count; ++n) {
if (namespace_files[n].fd != -1) {
close(namespace_files[n].fd);
namespace_files[n].fd = -1;
}
}
if (rc != 0) {
errno = err;
}
return rc;
}
#define ENV_PATH_FMT "/proc/%d/environ"
#define ENV_PATH_MAXLEN (6 + 10 + 8 + 1)
#define ENV_NAME "KRB5CCNAME"
#define ENV_PREFIX "KRB5CCNAME="
#define ENV_PREFIX_LEN 11
#define ENV_BUF_START (4096)
#define ENV_BUF_MAX (131072)
/**
* get_cachename_from_process_env - scrape value of $KRB5CCNAME out of the
* initiating process' environment.
* @pid: initiating pid value from the upcall string
*
* Open the /proc/<pid>/environ file for the given pid, and scrape it for
* KRB5CCNAME entries.
*
* We start with a page-size buffer, and then progressively double it until
* we can slurp in the whole thing.
*
* Note that this is not entirely reliable. If the process is sitting in a
* container or something, then this is almost certainly not going to point
* where you expect.
*
* Probably it just won't work, but could a user use this to trick cifs.upcall
* into reading a file outside the container, by setting KRB5CCNAME in a
* crafty way?
*/
static char *
get_cachename_from_process_env(pid_t pid)
{
int fd, ret;
ssize_t buflen;
ssize_t bufsize = ENV_BUF_START;
char pathname[ENV_PATH_MAXLEN];
char *cachename = NULL;
char *buf = NULL, *pos;
if (!pid) {
syslog(LOG_DEBUG, "%s: pid == 0\n", __func__);
return NULL;
}
pathname[ENV_PATH_MAXLEN - 1] = '\0';
ret = snprintf(pathname, ENV_PATH_MAXLEN, ENV_PATH_FMT, pid);
if (ret >= ENV_PATH_MAXLEN) {
syslog(LOG_DEBUG, "%s: unterminated path!\n", __func__);
return NULL;
}
syslog(LOG_DEBUG, "%s: pathname=%s\n", __func__, pathname);
fd = open(pathname, O_RDONLY);
if (fd < 0) {
syslog(LOG_DEBUG, "%s: open failed: %d\n", __func__, errno);
return NULL;
}
retry:
if (bufsize > ENV_BUF_MAX) {
syslog(LOG_DEBUG, "%s: buffer too big: %zd\n",
__func__, bufsize);
goto out_close;
}
buf = malloc(bufsize);
if (!buf) {
syslog(LOG_DEBUG, "%s: malloc failure\n", __func__);
goto out_close;
}
buflen = read(fd, buf, bufsize);
if (buflen < 0) {
syslog(LOG_DEBUG, "%s: read failed: %d\n", __func__, errno);
goto out_close;
}
if (buflen >= bufsize) {
/* We read to the end of the buffer. Double and try again */
syslog(LOG_DEBUG, "%s: read to end of buffer (%zu bytes)\n",
__func__, bufsize);
free(buf);
bufsize *= 2;
if (lseek(fd, 0, SEEK_SET) < 0)
goto out_close;
goto retry;
}
pos = buf;
while (buflen > 0) {
size_t len = strnlen(pos, buflen);
if (len > ENV_PREFIX_LEN &&
!memcmp(pos, ENV_PREFIX, ENV_PREFIX_LEN)) {
cachename = strndup(pos + ENV_PREFIX_LEN,
len - ENV_PREFIX_LEN);
syslog(LOG_DEBUG, "%s: cachename = %s\n",
__func__, cachename);
break;
}
buflen -= (len + 1);
pos += (len + 1);
}
out_close:
free(buf);
close(fd);
return cachename;
}
static krb5_ccache
get_existing_cc(const char *env_cachename)
{
krb5_error_code ret;
krb5_ccache cc;
char *cachename;
if (env_cachename) {
if (setenv(ENV_NAME, env_cachename, 1))
syslog(LOG_DEBUG, "%s: failed to setenv %d\n", __func__, errno);
}
ret = krb5_cc_default(context, &cc);
if (ret) {
syslog(LOG_DEBUG, "%s: krb5_cc_default returned %d", __func__, ret);
return NULL;
}
ret = krb5_cc_get_full_name(context, cc, &cachename);
if (ret) {
syslog(LOG_DEBUG, "%s: krb5_cc_get_full_name failed: %d\n", __func__, ret);
} else {
syslog(LOG_DEBUG, "%s: default ccache is %s\n", __func__, cachename);
krb5_free_string(context, cachename);
}
if (!get_tgt_time(cc)) {
krb5_cc_close(context, cc);
cc = NULL;
}
return cc;
}
static krb5_ccache
init_cc_from_keytab(const char *keytab_name, const char *user)
{
krb5_error_code ret;
krb5_creds my_creds;
krb5_keytab keytab = NULL;
krb5_principal me = NULL;
krb5_ccache cc = NULL;
memset((char *) &my_creds, 0, sizeof(my_creds));
/*
* Unset the environment variable, if any. If we're creating our own
* credcache here, stick it in the default location.
*/
unsetenv(ENV_NAME);
if (keytab_name)
ret = krb5_kt_resolve(context, keytab_name, &keytab);
else
ret = krb5_kt_default(context, &keytab);
if (ret) {
syslog(LOG_DEBUG, "%s: %d",
keytab_name ? "krb5_kt_resolve" : "krb5_kt_default",
(int)ret);
goto icfk_cleanup;
}
ret = krb5_parse_name(context, user, &me);
if (ret) {
syslog(LOG_DEBUG, "krb5_parse_name: %d", (int)ret);
goto icfk_cleanup;
}
ret = krb5_get_init_creds_keytab(context, &my_creds, me,
keytab, 0, NULL, NULL);
if (ret) {
syslog(LOG_DEBUG, "krb5_get_init_creds_keytab: %d", (int)ret);
goto icfk_cleanup;
}
ret = krb5_cc_resolve(context, "MEMORY:", &cc);
if (ret) {
syslog(LOG_DEBUG, "krb5_cc_resolve: %d", (int)ret);
goto icfk_cleanup;
}
ret = krb5_cc_initialize(context, cc, me);
if (ret) {
syslog(LOG_DEBUG, "krb5_cc_initialize: %d", (int)ret);
goto icfk_cleanup;
}
ret = krb5_cc_store_cred(context, cc, &my_creds);
if (ret) {
syslog(LOG_DEBUG, "krb5_cc_store_cred: %d", (int)ret);
goto icfk_cleanup;
}
out:
my_creds.client = (krb5_principal)0;
krb5_free_cred_contents(context, &my_creds);
if (me)
krb5_free_principal(context, me);
if (keytab)
krb5_kt_close(context, keytab);
return cc;
icfk_cleanup:
if (cc) {
krb5_cc_close(context, cc);
cc = NULL;
}
goto out;
}
#define CIFS_SERVICE_NAME "cifs"
static int
cifs_krb5_get_req(const char *host, krb5_ccache ccache,
DATA_BLOB * mechtoken, DATA_BLOB * sess_key)
{
krb5_error_code ret;
krb5_keyblock *tokb;
krb5_creds in_creds, *out_creds;
krb5_data apreq_pkt, in_data;
krb5_auth_context auth_context = NULL;
#if defined(HAVE_KRB5_AUTH_CON_SETADDRS) && defined(HAVE_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE)
static char gss_cksum[24] = { 0x10, 0x00, /* ... */};
#endif
memset(&in_creds, 0, sizeof(in_creds));
ret = krb5_cc_get_principal(context, ccache, &in_creds.client);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to get client principal name",
__func__);
return ret;
}
ret = krb5_sname_to_principal(context, host, CIFS_SERVICE_NAME,
KRB5_NT_UNKNOWN, &in_creds.server);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to convert sname to princ (%s).",
__func__, host);
goto out_free_principal;
}
ret = krb5_get_credentials(context, 0, ccache, &in_creds, &out_creds);
krb5_free_principal(context, in_creds.server);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to get credentials for %s",
__func__, host);
goto out_free_principal;
}
in_data.length = 0;
in_data.data = NULL;
ret = krb5_auth_con_init(context, &auth_context);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to create auth_context: %d",
__func__, ret);
goto out_free_creds;
}
#if defined(HAVE_KRB5_AUTH_CON_SETADDRS) && defined(HAVE_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE)
/* Ensure we will get an addressless ticket. */
ret = krb5_auth_con_setaddrs(context, auth_context, NULL, NULL);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to set NULL addrs: %d",
__func__, ret);
goto out_free_auth;
}
/*
* Create a GSSAPI checksum (0x8003), see RFC 4121.
*
* The current layout is
*
* 0x10, 0x00, 0x00, 0x00 - length = 16
* 0x00, 0x00, 0x00, 0x00 - channel binding info - 16 zero bytes
* 0x00, 0x00, 0x00, 0x00
* 0x00, 0x00, 0x00, 0x00
* 0x00, 0x00, 0x00, 0x00
* 0x00, 0x00, 0x00, 0x00 - flags
*
* GSS_C_NO_CHANNEL_BINDINGS means 16 zero bytes,
* this is needed to work against some closed source
* SMB servers.
*
* See https://bugzilla.samba.org/show_bug.cgi?id=7890
*/
in_data.data = gss_cksum;
in_data.length = 24;
/* MIT krb5 < 1.7 is missing the prototype, but still has the symbol */
#if !HAVE_DECL_KRB5_AUTH_CON_SET_REQ_CKSUMTYPE
krb5_error_code krb5_auth_con_set_req_cksumtype(
krb5_auth_context auth_context,
krb5_cksumtype cksumtype);
#endif
ret = krb5_auth_con_set_req_cksumtype(context, auth_context, 0x8003);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to set 0x8003 checksum",
__func__);
goto out_free_auth;
}
#endif
apreq_pkt.length = 0;
apreq_pkt.data = NULL;
ret = krb5_mk_req_extended(context, &auth_context, AP_OPTS_USE_SUBKEY,
&in_data, out_creds, &apreq_pkt);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to make AP-REQ for %s",
__func__, host);
goto out_free_auth;
}
ret = krb5_auth_con_getsendsubkey(context, auth_context, &tokb);
if (ret) {
syslog(LOG_DEBUG, "%s: unable to get session key for %s",
__func__, host);
goto out_free_auth;
}
*mechtoken = data_blob(apreq_pkt.data, apreq_pkt.length);
*sess_key = data_blob(KRB5_KEY_DATA(tokb), KRB5_KEY_LENGTH(tokb));
krb5_free_keyblock(context, tokb);
out_free_auth:
krb5_auth_con_free(context, auth_context);
out_free_creds:
krb5_free_creds(context, out_creds);
out_free_principal:
krb5_free_principal(context, in_creds.client);
return ret;
}
static void cifs_gss_display_status_1(char *m, OM_uint32 code, int type) {
OM_uint32 min_stat;
gss_buffer_desc msg;
OM_uint32 msg_ctx;
msg_ctx = 0;
while (1) {
(void) gss_display_status(&min_stat, code, type,
GSS_C_NULL_OID, &msg_ctx, &msg);
syslog(LOG_DEBUG, "GSS-API error %s: %s\n", m, (char *) msg.value);
(void) gss_release_buffer(&min_stat, &msg);
if (!msg_ctx)
break;
}
}
void cifs_gss_display_status(char *msg, OM_uint32 maj_stat, OM_uint32 min_stat) {
cifs_gss_display_status_1(msg, maj_stat, GSS_C_GSS_CODE);
cifs_gss_display_status_1(msg, min_stat, GSS_C_MECH_CODE);
}
static int
cifs_gss_get_req(const char *host, DATA_BLOB *mechtoken, DATA_BLOB *sess_key)
{
OM_uint32 maj_stat, min_stat;
gss_name_t target_name;
gss_ctx_id_t ctx = GSS_C_NO_CONTEXT;
gss_buffer_desc output_token;
gss_krb5_lucid_context_v1_t *lucid_ctx = NULL;
gss_krb5_lucid_key_t *key = NULL;
size_t service_name_len = sizeof(CIFS_SERVICE_NAME) + 1 /* @ */ +
strlen(host) + 1;
char *service_name = malloc(service_name_len);
if (!service_name) {
syslog(LOG_DEBUG, "out of memory allocating service name");
maj_stat = GSS_S_FAILURE;
goto out;
}
snprintf(service_name, service_name_len, "%s@%s", CIFS_SERVICE_NAME,
host);
gss_buffer_desc target_name_buf;
target_name_buf.value = service_name;
target_name_buf.length = service_name_len;
maj_stat = gss_import_name(&min_stat, &target_name_buf,
GSS_C_NT_HOSTBASED_SERVICE, &target_name);
free(service_name);
if (GSS_ERROR(maj_stat)) {
cifs_gss_display_status("gss_import_name", maj_stat, min_stat);
goto out;
}
maj_stat = gss_init_sec_context(&min_stat,
GSS_C_NO_CREDENTIAL, /* claimant_cred_handle */
&ctx,
target_name,
discard_const(gss_mech_krb5), /* force krb5 */
0, /* flags */
0, /* time_req */
GSS_C_NO_CHANNEL_BINDINGS, /* input_chan_bindings */
GSS_C_NO_BUFFER,
NULL, /* actual mech type */
&output_token,
NULL, /* ret_flags */
NULL); /* time_rec */
if (maj_stat != GSS_S_COMPLETE &&
maj_stat != GSS_S_CONTINUE_NEEDED) {
cifs_gss_display_status("init_sec_context", maj_stat, min_stat);
goto out_release_target_name;
}
/* as luck would have it, GSS-API hands us the finished article */
*mechtoken = data_blob(output_token.value, output_token.length);
maj_stat = gss_krb5_export_lucid_sec_context(&min_stat, &ctx, 1,
(void **)&lucid_ctx);
if (GSS_ERROR(maj_stat)) {
cifs_gss_display_status("gss_krb5_export_lucid_sec_context",
maj_stat, min_stat);
goto out_free_sec_ctx;
}
switch (lucid_ctx->protocol) {
case 0:
key = &lucid_ctx->rfc1964_kd.ctx_key;
break;
case 1:
if (lucid_ctx->cfx_kd.have_acceptor_subkey) {
key = &lucid_ctx->cfx_kd.acceptor_subkey;
} else {
key = &lucid_ctx->cfx_kd.ctx_key;
}
break;
default:
syslog(LOG_DEBUG, "wrong lucid context protocol %d",
lucid_ctx->protocol);
goto out_free_lucid_ctx;
}
*sess_key = data_blob(key->data, key->length);
out_free_lucid_ctx:
(void) gss_krb5_free_lucid_sec_context(&min_stat, lucid_ctx);
out_free_sec_ctx:
(void) gss_delete_sec_context(&min_stat, &ctx, GSS_C_NO_BUFFER);
(void) gss_release_buffer(&min_stat, &output_token);
out_release_target_name:
(void) gss_release_name(&min_stat, &target_name);
out:
return GSS_ERROR(maj_stat);
}
/*
* Prepares AP-REQ data for mechToken and gets session key
* Uses credentials from cache. It will not ask for password
* you should receive credentials for yuor name manually using
* kinit or whatever you wish.
*
* in:
* oid - string with OID/ Could be OID_KERBEROS5
* or OID_KERBEROS5_OLD
* principal - Service name.
* Could be "cifs/FQDN" for KRB5 OID
* or for MS_KRB5 OID style server principal
* like "[email protected]"
*
* out:
* secblob - pointer for spnego wrapped AP-REQ data to be stored
* sess_key- pointer for SessionKey data to be stored
*
* ret: 0 - success, others - failure
*/
static int
handle_krb5_mech(const char *oid, const char *host, DATA_BLOB * secblob,
DATA_BLOB * sess_key, krb5_ccache ccache)
{
int retval;
DATA_BLOB tkt_wrapped;
syslog(LOG_DEBUG, "%s: getting service ticket for %s", __func__, host);
/*
* Fall back to gssapi if there's no credential cache or no TGT
* so that gssproxy can maybe help out.
*/
if (!ccache) {
syslog(LOG_DEBUG, "%s: using GSS-API", __func__);
retval = cifs_gss_get_req(host, &tkt_wrapped, sess_key);
if (retval) {
syslog(LOG_DEBUG, "%s: failed to obtain service ticket via GSS (%d)",
__func__, retval);
return retval;
}
} else {
DATA_BLOB tkt;
syslog(LOG_DEBUG, "%s: using native krb5", __func__);
/* get a kerberos ticket for the service and extract the session key */
retval = cifs_krb5_get_req(host, ccache, &tkt, sess_key);
if (retval) {
syslog(LOG_DEBUG, "%s: failed to obtain service ticket (%d)",
__func__, retval);
return retval;
}
syslog(LOG_DEBUG, "%s: obtained service ticket", __func__);
/* wrap that up in a nice GSS-API wrapping */
tkt_wrapped = spnego_gen_krb5_wrap(tkt, TOK_ID_KRB_AP_REQ);
data_blob_free(&tkt);
}
/* and wrap that in a shiny SPNEGO wrapper */
*secblob = gen_negTokenInit(oid, tkt_wrapped);
data_blob_free(&tkt_wrapped);
return retval;
}
struct decoded_args {
int ver;
char hostname[NI_MAXHOST + 1];
char ip[NI_MAXHOST + 1];
/* Max user name length. */
#define MAX_USERNAME_SIZE 256
char username[MAX_USERNAME_SIZE + 1];
uid_t uid;
uid_t creduid;
pid_t pid;
sectype_t sec;
/*
* Flags to keep track of what was provided
*/
#define DKD_HAVE_HOSTNAME 0x1
#define DKD_HAVE_VERSION 0x2
#define DKD_HAVE_SEC 0x4
#define DKD_HAVE_IP 0x8
#define DKD_HAVE_UID 0x10
#define DKD_HAVE_PID 0x20
#define DKD_HAVE_CREDUID 0x40
#define DKD_HAVE_USERNAME 0x80
#define DKD_MUSTHAVE_SET (DKD_HAVE_HOSTNAME|DKD_HAVE_VERSION|DKD_HAVE_SEC)
int have;
};
static unsigned int
__decode_key_description(const char *desc, struct decoded_args *arg)
{
size_t len;
char *pos;
const char *tkn = desc;
do {
pos = index(tkn, ';');
if (strncmp(tkn, "host=", 5) == 0) {
if (pos == NULL)
len = strlen(tkn);
else
len = pos - tkn;
len -= 5;
if (len > sizeof(arg->hostname)-1) {
syslog(LOG_ERR, "host= value too long for buffer");
return 1;
}
memset(arg->hostname, 0, sizeof(arg->hostname));
strncpy(arg->hostname, tkn + 5, len);
arg->have |= DKD_HAVE_HOSTNAME;
syslog(LOG_DEBUG, "host=%s", arg->hostname);