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authorVasily Averin <vvs@virtuozzo.com>2018-12-24 14:44:52 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-16 22:16:12 +0100
commit9615b6aeccbfb233fd672107aa6885bf039c3de3 (patch)
treeeeca274c8ddc354a01ca2169e57fadf974b55110
parent3897b4ae1fdc2cdc90594f817c69166855139c06 (diff)
sunrpc: use-after-free in svc_process_common()
commit d4b09acf924b84bae77cad090a9d108e70b43643 upstream. if node have NFSv41+ mounts inside several net namespaces it can lead to use-after-free in svc_process_common() svc_process_common() /* Setup reply header */ rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(rqstp); <<< HERE svc_process_common() can use incorrect rqstp->rq_xprt, its caller function bc_svc_process() takes it from serv->sv_bc_xprt. The problem is that serv is global structure but sv_bc_xprt is assigned per-netnamespace. According to Trond, the whole "let's set up rqstp->rq_xprt for the back channel" is nothing but a giant hack in order to work around the fact that svc_process_common() uses it to find the xpt_ops, and perform a couple of (meaningless for the back channel) tests of xpt_flags. All we really need in svc_process_common() is to be able to run rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr() Bruce J Fields points that this xpo_prep_reply_hdr() call is an awfully roundabout way just to do "svc_putnl(resv, 0);" in the tcp case. This patch does not initialiuze rqstp->rq_xprt in bc_svc_process(), now it calls svc_process_common() with rqstp->rq_xprt = NULL. To adjust reply header svc_process_common() just check rqstp->rq_prot and calls svc_tcp_prep_reply_hdr() for tcp case. To handle rqstp->rq_xprt = NULL case in functions called from svc_process_common() patch intruduces net namespace pointer svc_rqst->rq_bc_net and adjust SVC_NET() definition. Some other function was also adopted to properly handle described case. Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Cc: stable@vger.kernel.org Fixes: 23c20ecd4475 ("NFS: callback up - users counting cleanup") Signed-off-by: J. Bruce Fields <bfields@redhat.com> v2: - added lost extern svc_tcp_prep_reply_hdr() - dropped trace_svc_process() changes - context fixes in svc_process_common() Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/linux/sunrpc/svc.h5
-rw-r--r--net/sunrpc/svc.c10
-rw-r--r--net/sunrpc/svc_xprt.c5
-rw-r--r--net/sunrpc/svcsock.c2
4 files changed, 15 insertions, 7 deletions
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index cc0fc712bb82..a8ac3f25b4ec 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -290,9 +290,12 @@ struct svc_rqst {
struct svc_cacherep * rq_cacherep; /* cache info */
struct task_struct *rq_task; /* service thread */
spinlock_t rq_lock; /* per-request lock */
+ struct net *rq_bc_net; /* pointer to backchannel's
+ * net namespace
+ */
};
-#define SVC_NET(svc_rqst) (svc_rqst->rq_xprt->xpt_net)
+#define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)
/*
* Rigorous type checking on sockaddr type conversions
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index c5b0cb4f4056..41f6e964fe91 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1062,6 +1062,8 @@ void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...)
static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {}
#endif
+extern void svc_tcp_prep_reply_hdr(struct svc_rqst *);
+
/*
* Common routine for processing the RPC request.
*/
@@ -1091,7 +1093,8 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
clear_bit(RQ_DROPME, &rqstp->rq_flags);
/* Setup reply header */
- rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(rqstp);
+ if (rqstp->rq_prot == IPPROTO_TCP)
+ svc_tcp_prep_reply_hdr(rqstp);
svc_putu32(resv, rqstp->rq_xid);
@@ -1138,7 +1141,8 @@ svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
case SVC_DENIED:
goto err_bad_auth;
case SVC_CLOSE:
- if (test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
+ if (rqstp->rq_xprt &&
+ test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
svc_close_xprt(rqstp->rq_xprt);
case SVC_DROP:
goto dropit;
@@ -1360,10 +1364,10 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
dprintk("svc: %s(%p)\n", __func__, req);
/* Build the svc_rqst used by the common processing routine */
- rqstp->rq_xprt = serv->sv_bc_xprt;
rqstp->rq_xid = req->rq_xid;
rqstp->rq_prot = req->rq_xprt->prot;
rqstp->rq_server = serv;
+ rqstp->rq_bc_net = req->rq_xprt->xprt_net;
rqstp->rq_addrlen = sizeof(req->rq_xprt->addr);
memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 71f15da72f02..2b8e80c721db 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -454,10 +454,11 @@ out:
*/
void svc_reserve(struct svc_rqst *rqstp, int space)
{
+ struct svc_xprt *xprt = rqstp->rq_xprt;
+
space += rqstp->rq_res.head[0].iov_len;
- if (space < rqstp->rq_reserved) {
- struct svc_xprt *xprt = rqstp->rq_xprt;
+ if (xprt && space < rqstp->rq_reserved) {
atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved);
rqstp->rq_reserved = space;
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 9701fcca002c..0a9fe033132c 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1240,7 +1240,7 @@ static int svc_tcp_sendto(struct svc_rqst *rqstp)
/*
* Setup response header. TCP has a 4B record length field.
*/
-static void svc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
+void svc_tcp_prep_reply_hdr(struct svc_rqst *rqstp)
{
struct kvec *resv = &rqstp->rq_res.head[0];