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linux/fs/lockd/xdr4.c
Jeff Layton 6930bcbfb6 lockd: detect and reject lock arguments that overflow 
lockd doesn't currently vet the start and length in nlm4 requests like
it should, and can end up generating lock requests with arguments that
overflow when passed to the filesystem.

The NLM4 protocol uses unsigned 64-bit arguments for both start and
length, whereas struct file_lock tracks the start and end as loff_t
values. By the time we get around to calling nlm4svc_retrieve_args,
we've lost the information that would allow us to determine if there was
an overflow.

Start tracking the actual start and len for NLM4 requests in the
nlm_lock. In nlm4svc_retrieve_args, vet these values to ensure they
won't cause an overflow, and return NLM4_FBIG if they do.

Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=392
Reported-by: Jan Kasiak <j.kasiak@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: <stable@vger.kernel.org> # 5.14+
2022-08-04 10:28:48 -04:00

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/lockd/xdr4.c
*
* XDR support for lockd and the lock client.
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
* Copyright (C) 1999, Trond Myklebust <trond.myklebust@fys.uio.no>
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/nfs.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/stats.h>
#include <linux/lockd/lockd.h>
#include "svcxdr.h"
static inline s64
loff_t_to_s64(loff_t offset)
{
s64 res;
if (offset > NLM4_OFFSET_MAX)
res = NLM4_OFFSET_MAX;
else if (offset < -NLM4_OFFSET_MAX)
res = -NLM4_OFFSET_MAX;
else
res = offset;
return res;
}
/*
* NLM file handles are defined by specification to be a variable-length
* XDR opaque no longer than 1024 bytes. However, this implementation
* limits their length to the size of an NFSv3 file handle.
*/
static bool
svcxdr_decode_fhandle(struct xdr_stream *xdr, struct nfs_fh *fh)
{
__be32 *p;
u32 len;
if (xdr_stream_decode_u32(xdr, &len) < 0)
return false;
if (len > NFS_MAXFHSIZE)
return false;
p = xdr_inline_decode(xdr, len);
if (!p)
return false;
fh->size = len;
memcpy(fh->data, p, len);
memset(fh->data + len, 0, sizeof(fh->data) - len);
return true;
}
static bool
svcxdr_decode_lock(struct xdr_stream *xdr, struct nlm_lock *lock)
{
struct file_lock *fl = &lock->fl;
if (!svcxdr_decode_string(xdr, &lock->caller, &lock->len))
return false;
if (!svcxdr_decode_fhandle(xdr, &lock->fh))
return false;
if (!svcxdr_decode_owner(xdr, &lock->oh))
return false;
if (xdr_stream_decode_u32(xdr, &lock->svid) < 0)
return false;
if (xdr_stream_decode_u64(xdr, &lock->lock_start) < 0)
return false;
if (xdr_stream_decode_u64(xdr, &lock->lock_len) < 0)
return false;
locks_init_lock(fl);
fl->fl_flags = FL_POSIX;
fl->fl_type = F_RDLCK;
return true;
}
static bool
svcxdr_encode_holder(struct xdr_stream *xdr, const struct nlm_lock *lock)
{
const struct file_lock *fl = &lock->fl;
s64 start, len;
/* exclusive */
if (xdr_stream_encode_bool(xdr, fl->fl_type != F_RDLCK) < 0)
return false;
if (xdr_stream_encode_u32(xdr, lock->svid) < 0)
return false;
if (!svcxdr_encode_owner(xdr, &lock->oh))
return false;
start = loff_t_to_s64(fl->fl_start);
if (fl->fl_end == OFFSET_MAX)
len = 0;
else
len = loff_t_to_s64(fl->fl_end - fl->fl_start + 1);
if (xdr_stream_encode_u64(xdr, start) < 0)
return false;
if (xdr_stream_encode_u64(xdr, len) < 0)
return false;
return true;
}
static bool
svcxdr_encode_testrply(struct xdr_stream *xdr, const struct nlm_res *resp)
{
if (!svcxdr_encode_stats(xdr, resp->status))
return false;
switch (resp->status) {
case nlm_lck_denied:
if (!svcxdr_encode_holder(xdr, &resp->lock))
return false;
}
return true;
}
/*
* Decode Call arguments
*/
bool
nlm4svc_decode_void(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
return true;
}
bool
nlm4svc_decode_testargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
u32 exclusive;
if (!svcxdr_decode_cookie(xdr, &argp->cookie))
return false;
if (xdr_stream_decode_bool(xdr, &exclusive) < 0)
return false;
if (!svcxdr_decode_lock(xdr, &argp->lock))
return false;
if (exclusive)
argp->lock.fl.fl_type = F_WRLCK;
return true;
}
bool
nlm4svc_decode_lockargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
u32 exclusive;
if (!svcxdr_decode_cookie(xdr, &argp->cookie))
return false;
if (xdr_stream_decode_bool(xdr, &argp->block) < 0)
return false;
if (xdr_stream_decode_bool(xdr, &exclusive) < 0)
return false;
if (!svcxdr_decode_lock(xdr, &argp->lock))
return false;
if (exclusive)
argp->lock.fl.fl_type = F_WRLCK;
if (xdr_stream_decode_bool(xdr, &argp->reclaim) < 0)
return false;
if (xdr_stream_decode_u32(xdr, &argp->state) < 0)
return false;
argp->monitor = 1; /* monitor client by default */
return true;
}
bool
nlm4svc_decode_cancargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
u32 exclusive;
if (!svcxdr_decode_cookie(xdr, &argp->cookie))
return false;
if (xdr_stream_decode_bool(xdr, &argp->block) < 0)
return false;
if (xdr_stream_decode_bool(xdr, &exclusive) < 0)
return false;
if (!svcxdr_decode_lock(xdr, &argp->lock))
return false;
if (exclusive)
argp->lock.fl.fl_type = F_WRLCK;
return true;
}
bool
nlm4svc_decode_unlockargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
if (!svcxdr_decode_cookie(xdr, &argp->cookie))
return false;
if (!svcxdr_decode_lock(xdr, &argp->lock))
return false;
argp->lock.fl.fl_type = F_UNLCK;
return true;
}
bool
nlm4svc_decode_res(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_res *resp = rqstp->rq_argp;
if (!svcxdr_decode_cookie(xdr, &resp->cookie))
return false;
if (!svcxdr_decode_stats(xdr, &resp->status))
return false;
return true;
}
bool
nlm4svc_decode_reboot(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_reboot *argp = rqstp->rq_argp;
__be32 *p;
u32 len;
if (xdr_stream_decode_u32(xdr, &len) < 0)
return false;
if (len > SM_MAXSTRLEN)
return false;
p = xdr_inline_decode(xdr, len);
if (!p)
return false;
argp->len = len;
argp->mon = (char *)p;
if (xdr_stream_decode_u32(xdr, &argp->state) < 0)
return false;
p = xdr_inline_decode(xdr, SM_PRIV_SIZE);
if (!p)
return false;
memcpy(&argp->priv.data, p, sizeof(argp->priv.data));
return true;
}
bool
nlm4svc_decode_shareargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
struct nlm_lock *lock = &argp->lock;
memset(lock, 0, sizeof(*lock));
locks_init_lock(&lock->fl);
lock->svid = ~(u32)0;
if (!svcxdr_decode_cookie(xdr, &argp->cookie))
return false;
if (!svcxdr_decode_string(xdr, &lock->caller, &lock->len))
return false;
if (!svcxdr_decode_fhandle(xdr, &lock->fh))
return false;
if (!svcxdr_decode_owner(xdr, &lock->oh))
return false;
/* XXX: Range checks are missing in the original code */
if (xdr_stream_decode_u32(xdr, &argp->fsm_mode) < 0)
return false;
if (xdr_stream_decode_u32(xdr, &argp->fsm_access) < 0)
return false;
return true;
}
bool
nlm4svc_decode_notify(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_args *argp = rqstp->rq_argp;
struct nlm_lock *lock = &argp->lock;
if (!svcxdr_decode_string(xdr, &lock->caller, &lock->len))
return false;
if (xdr_stream_decode_u32(xdr, &argp->state) < 0)
return false;
return true;
}
/*
* Encode Reply results
*/
bool
nlm4svc_encode_void(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
return true;
}
bool
nlm4svc_encode_testres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_res *resp = rqstp->rq_resp;
return svcxdr_encode_cookie(xdr, &resp->cookie) &&
svcxdr_encode_testrply(xdr, resp);
}
bool
nlm4svc_encode_res(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_res *resp = rqstp->rq_resp;
return svcxdr_encode_cookie(xdr, &resp->cookie) &&
svcxdr_encode_stats(xdr, resp->status);
}
bool
nlm4svc_encode_shareres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
struct nlm_res *resp = rqstp->rq_resp;
if (!svcxdr_encode_cookie(xdr, &resp->cookie))
return false;
if (!svcxdr_encode_stats(xdr, resp->status))
return false;
/* sequence */
if (xdr_stream_encode_u32(xdr, 0) < 0)
return false;
return true;
}
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