alistair23-linux/net/sunrpc/auth_gss/gss_rpc_upcall.c
David Ramos a1d1e9be5a svcrpc: fix memory leak in gssp_accept_sec_context_upcall
Our UC-KLEE tool found a kernel memory leak of 512 bytes (on x86_64) for
each call to gssp_accept_sec_context_upcall()
(net/sunrpc/auth_gss/gss_rpc_upcall.c). Since it appears that this call
can be triggered by remote connections (at least, from a cursory a
glance at the call chain), it may be exploitable to cause kernel memory
exhaustion. We found the bug in kernel 3.16.3, but it appears to date
back to commit 9dfd87da1a (2013-08-20).

The gssp_accept_sec_context_upcall() function performs a pair of calls
to gssp_alloc_receive_pages() and gssp_free_receive_pages().  The first
allocates memory for arg->pages.  The second then frees the pages
pointed to by the arg->pages array, but not the array itself.

Reported-by: David A. Ramos <daramos@stanford.edu>
Fixes: 9dfd87da1a ("rpc: fix huge kmalloc's in gss-proxy”)
Signed-off-by: David A. Ramos <daramos@stanford.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2015-02-17 18:09:02 -05:00

385 lines
9.4 KiB
C

/*
* linux/net/sunrpc/gss_rpc_upcall.c
*
* Copyright (C) 2012 Simo Sorce <simo@redhat.com>
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/types.h>
#include <linux/un.h>
#include <linux/sunrpc/svcauth.h>
#include "gss_rpc_upcall.h"
#define GSSPROXY_SOCK_PATHNAME "/var/run/gssproxy.sock"
#define GSSPROXY_PROGRAM (400112u)
#define GSSPROXY_VERS_1 (1u)
/*
* Encoding/Decoding functions
*/
enum {
GSSX_NULL = 0, /* Unused */
GSSX_INDICATE_MECHS = 1,
GSSX_GET_CALL_CONTEXT = 2,
GSSX_IMPORT_AND_CANON_NAME = 3,
GSSX_EXPORT_CRED = 4,
GSSX_IMPORT_CRED = 5,
GSSX_ACQUIRE_CRED = 6,
GSSX_STORE_CRED = 7,
GSSX_INIT_SEC_CONTEXT = 8,
GSSX_ACCEPT_SEC_CONTEXT = 9,
GSSX_RELEASE_HANDLE = 10,
GSSX_GET_MIC = 11,
GSSX_VERIFY = 12,
GSSX_WRAP = 13,
GSSX_UNWRAP = 14,
GSSX_WRAP_SIZE_LIMIT = 15,
};
#define PROC(proc, name) \
[GSSX_##proc] = { \
.p_proc = GSSX_##proc, \
.p_encode = (kxdreproc_t)gssx_enc_##name, \
.p_decode = (kxdrdproc_t)gssx_dec_##name, \
.p_arglen = GSSX_ARG_##name##_sz, \
.p_replen = GSSX_RES_##name##_sz, \
.p_statidx = GSSX_##proc, \
.p_name = #proc, \
}
static struct rpc_procinfo gssp_procedures[] = {
PROC(INDICATE_MECHS, indicate_mechs),
PROC(GET_CALL_CONTEXT, get_call_context),
PROC(IMPORT_AND_CANON_NAME, import_and_canon_name),
PROC(EXPORT_CRED, export_cred),
PROC(IMPORT_CRED, import_cred),
PROC(ACQUIRE_CRED, acquire_cred),
PROC(STORE_CRED, store_cred),
PROC(INIT_SEC_CONTEXT, init_sec_context),
PROC(ACCEPT_SEC_CONTEXT, accept_sec_context),
PROC(RELEASE_HANDLE, release_handle),
PROC(GET_MIC, get_mic),
PROC(VERIFY, verify),
PROC(WRAP, wrap),
PROC(UNWRAP, unwrap),
PROC(WRAP_SIZE_LIMIT, wrap_size_limit),
};
/*
* Common transport functions
*/
static const struct rpc_program gssp_program;
static int gssp_rpc_create(struct net *net, struct rpc_clnt **_clnt)
{
static const struct sockaddr_un gssp_localaddr = {
.sun_family = AF_LOCAL,
.sun_path = GSSPROXY_SOCK_PATHNAME,
};
struct rpc_create_args args = {
.net = net,
.protocol = XPRT_TRANSPORT_LOCAL,
.address = (struct sockaddr *)&gssp_localaddr,
.addrsize = sizeof(gssp_localaddr),
.servername = "localhost",
.program = &gssp_program,
.version = GSSPROXY_VERS_1,
.authflavor = RPC_AUTH_NULL,
/*
* Note we want connection to be done in the caller's
* filesystem namespace. We therefore turn off the idle
* timeout, which would result in reconnections being
* done without the correct namespace:
*/
.flags = RPC_CLNT_CREATE_NOPING |
RPC_CLNT_CREATE_NO_IDLE_TIMEOUT
};
struct rpc_clnt *clnt;
int result = 0;
clnt = rpc_create(&args);
if (IS_ERR(clnt)) {
dprintk("RPC: failed to create AF_LOCAL gssproxy "
"client (errno %ld).\n", PTR_ERR(clnt));
result = PTR_ERR(clnt);
*_clnt = NULL;
goto out;
}
dprintk("RPC: created new gssp local client (gssp_local_clnt: "
"%p)\n", clnt);
*_clnt = clnt;
out:
return result;
}
void init_gssp_clnt(struct sunrpc_net *sn)
{
mutex_init(&sn->gssp_lock);
sn->gssp_clnt = NULL;
}
int set_gssp_clnt(struct net *net)
{
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
struct rpc_clnt *clnt;
int ret;
mutex_lock(&sn->gssp_lock);
ret = gssp_rpc_create(net, &clnt);
if (!ret) {
if (sn->gssp_clnt)
rpc_shutdown_client(sn->gssp_clnt);
sn->gssp_clnt = clnt;
}
mutex_unlock(&sn->gssp_lock);
return ret;
}
void clear_gssp_clnt(struct sunrpc_net *sn)
{
mutex_lock(&sn->gssp_lock);
if (sn->gssp_clnt) {
rpc_shutdown_client(sn->gssp_clnt);
sn->gssp_clnt = NULL;
}
mutex_unlock(&sn->gssp_lock);
}
static struct rpc_clnt *get_gssp_clnt(struct sunrpc_net *sn)
{
struct rpc_clnt *clnt;
mutex_lock(&sn->gssp_lock);
clnt = sn->gssp_clnt;
if (clnt)
atomic_inc(&clnt->cl_count);
mutex_unlock(&sn->gssp_lock);
return clnt;
}
static int gssp_call(struct net *net, struct rpc_message *msg)
{
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
struct rpc_clnt *clnt;
int status;
clnt = get_gssp_clnt(sn);
if (!clnt)
return -EIO;
status = rpc_call_sync(clnt, msg, 0);
if (status < 0) {
dprintk("gssp: rpc_call returned error %d\n", -status);
switch (status) {
case -EPROTONOSUPPORT:
status = -EINVAL;
break;
case -ECONNREFUSED:
case -ETIMEDOUT:
case -ENOTCONN:
status = -EAGAIN;
break;
case -ERESTARTSYS:
if (signalled ())
status = -EINTR;
break;
default:
break;
}
}
rpc_release_client(clnt);
return status;
}
static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
{
int i;
for (i = 0; i < arg->npages && arg->pages[i]; i++)
__free_page(arg->pages[i]);
kfree(arg->pages);
}
static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
{
arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
arg->pages = kzalloc(arg->npages * sizeof(struct page *), GFP_KERNEL);
/*
* XXX: actual pages are allocated by xdr layer in
* xdr_partial_copy_from_skb.
*/
if (!arg->pages)
return -ENOMEM;
return 0;
}
/*
* Public functions
*/
/* numbers somewhat arbitrary but large enough for current needs */
#define GSSX_MAX_OUT_HANDLE 128
#define GSSX_MAX_SRC_PRINC 256
#define GSSX_KMEMBUF (GSSX_max_output_handle_sz + \
GSSX_max_oid_sz + \
GSSX_max_princ_sz + \
sizeof(struct svc_cred))
int gssp_accept_sec_context_upcall(struct net *net,
struct gssp_upcall_data *data)
{
struct gssx_ctx ctxh = {
.state = data->in_handle
};
struct gssx_arg_accept_sec_context arg = {
.input_token = data->in_token,
};
struct gssx_ctx rctxh = {
/*
* pass in the max length we expect for each of these
* buffers but let the xdr code kmalloc them:
*/
.exported_context_token.len = GSSX_max_output_handle_sz,
.mech.len = GSS_OID_MAX_LEN,
.src_name.display_name.len = GSSX_max_princ_sz
};
struct gssx_res_accept_sec_context res = {
.context_handle = &rctxh,
.output_token = &data->out_token
};
struct rpc_message msg = {
.rpc_proc = &gssp_procedures[GSSX_ACCEPT_SEC_CONTEXT],
.rpc_argp = &arg,
.rpc_resp = &res,
.rpc_cred = NULL, /* FIXME ? */
};
struct xdr_netobj client_name = { 0 , NULL };
int ret;
if (data->in_handle.len != 0)
arg.context_handle = &ctxh;
res.output_token->len = GSSX_max_output_token_sz;
ret = gssp_alloc_receive_pages(&arg);
if (ret)
return ret;
/* use nfs/ for targ_name ? */
ret = gssp_call(net, &msg);
gssp_free_receive_pages(&arg);
/* we need to fetch all data even in case of error so
* that we can free special strctures is they have been allocated */
data->major_status = res.status.major_status;
data->minor_status = res.status.minor_status;
if (res.context_handle) {
data->out_handle = rctxh.exported_context_token;
data->mech_oid.len = rctxh.mech.len;
if (rctxh.mech.data)
memcpy(data->mech_oid.data, rctxh.mech.data,
data->mech_oid.len);
client_name = rctxh.src_name.display_name;
}
if (res.options.count == 1) {
gssx_buffer *value = &res.options.data[0].value;
/* Currently we only decode CREDS_VALUE, if we add
* anything else we'll have to loop and match on the
* option name */
if (value->len == 1) {
/* steal group info from struct svc_cred */
data->creds = *(struct svc_cred *)value->data;
data->found_creds = 1;
}
/* whether we use it or not, free data */
kfree(value->data);
}
if (res.options.count != 0) {
kfree(res.options.data);
}
/* convert to GSS_NT_HOSTBASED_SERVICE form and set into creds */
if (data->found_creds && client_name.data != NULL) {
char *c;
data->creds.cr_principal = kstrndup(client_name.data,
client_name.len, GFP_KERNEL);
if (data->creds.cr_principal) {
/* terminate and remove realm part */
c = strchr(data->creds.cr_principal, '@');
if (c) {
*c = '\0';
/* change service-hostname delimiter */
c = strchr(data->creds.cr_principal, '/');
if (c) *c = '@';
}
if (!c) {
/* not a service principal */
kfree(data->creds.cr_principal);
data->creds.cr_principal = NULL;
}
}
}
kfree(client_name.data);
return ret;
}
void gssp_free_upcall_data(struct gssp_upcall_data *data)
{
kfree(data->in_handle.data);
kfree(data->out_handle.data);
kfree(data->out_token.data);
free_svc_cred(&data->creds);
}
/*
* Initialization stuff
*/
static const struct rpc_version gssp_version1 = {
.number = GSSPROXY_VERS_1,
.nrprocs = ARRAY_SIZE(gssp_procedures),
.procs = gssp_procedures,
};
static const struct rpc_version *gssp_version[] = {
NULL,
&gssp_version1,
};
static struct rpc_stat gssp_stats;
static const struct rpc_program gssp_program = {
.name = "gssproxy",
.number = GSSPROXY_PROGRAM,
.nrvers = ARRAY_SIZE(gssp_version),
.version = gssp_version,
.stats = &gssp_stats,
};