[PATCH 3.12 049/116] lockd: create NSM handles per net namespace

From: Jiri Slaby
Date: Fri Mar 04 2016 - 04:35:40 EST

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From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 0ad95472bf169a3501991f8f33f5147f792a8116 upstream.

Commit cb7323fffa85 ("lockd: create and use per-net NSM
RPC clients on MON/UNMON requests") introduced per-net
NSM RPC clients. Unfortunately this doesn't make any sense
without per-net nsm_handle.

E.g. the following scenario could happen
Two hosts (X and Y) in different namespaces (A and B) share
the same nsm struct.

1. nsm_monitor(host_X) called => NSM rpc client created,
nsm->sm_monitored bit set.
2. nsm_mointor(host-Y) called => nsm->sm_monitored already set,
we just exit. Thus in namespace B ln->nsm_clnt == NULL.
3. host X destroyed => nsm->sm_count decremented to 1
4. host Y destroyed => nsm_unmonitor() => nsm_mon_unmon() => NULL-ptr
dereference of *ln->nsm_clnt

So this could be fixed by making per-net nsm_handles list,
instead of global. Thus different net namespaces will not be able
share the same nsm_handle.

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/lockd/host.c | 7 ++++---
fs/lockd/mon.c | 36 ++++++++++++++++++++++--------------
fs/lockd/netns.h | 1 +
fs/lockd/svc.c | 1 +
fs/lockd/svc4proc.c | 2 +-
fs/lockd/svcproc.c | 2 +-
include/linux/lockd/lockd.h | 9 ++++++---
7 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 969d589c848d..b5f3c3ab0d5f 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -116,7 +116,7 @@ static struct nlm_host *nlm_alloc_host(struct nlm_lookup_host_info *ni,
atomic_inc(&nsm->sm_count);
else {
host = NULL;
- nsm = nsm_get_handle(ni->sap, ni->salen,
+ nsm = nsm_get_handle(ni->net, ni->sap, ni->salen,
ni->hostname, ni->hostname_len);
if (unlikely(nsm == NULL)) {
dprintk("lockd: %s failed; no nsm handle\n",
@@ -534,17 +534,18 @@ static struct nlm_host *next_host_state(struct hlist_head *cache,

/**
* nlm_host_rebooted - Release all resources held by rebooted host
+ * @net: network namespace
* @info: pointer to decoded results of NLM_SM_NOTIFY call
*
* We were notified that the specified host has rebooted. Release
* all resources held by that peer.
*/
-void nlm_host_rebooted(const struct nlm_reboot *info)
+void nlm_host_rebooted(const struct net *net, const struct nlm_reboot *info)
{
struct nsm_handle *nsm;
struct nlm_host *host;

- nsm = nsm_reboot_lookup(info);
+ nsm = nsm_reboot_lookup(net, info);
if (unlikely(nsm == NULL))
return;

diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 6ae664b489af..13fac49aff7f 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -51,7 +51,6 @@ struct nsm_res {
};

static const struct rpc_program nsm_program;
-static LIST_HEAD(nsm_handles);
static DEFINE_SPINLOCK(nsm_lock);

/*
@@ -259,33 +258,35 @@ void nsm_unmonitor(const struct nlm_host *host)
}
}

-static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
- const size_t len)
+static struct nsm_handle *nsm_lookup_hostname(const struct list_head *nsm_handles,
+ const char *hostname, const size_t len)
{
struct nsm_handle *nsm;

- list_for_each_entry(nsm, &nsm_handles, sm_link)
+ list_for_each_entry(nsm, nsm_handles, sm_link)
if (strlen(nsm->sm_name) == len &&
memcmp(nsm->sm_name, hostname, len) == 0)
return nsm;
return NULL;
}

-static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
+static struct nsm_handle *nsm_lookup_addr(const struct list_head *nsm_handles,
+ const struct sockaddr *sap)
{
struct nsm_handle *nsm;

- list_for_each_entry(nsm, &nsm_handles, sm_link)
+ list_for_each_entry(nsm, nsm_handles, sm_link)
if (rpc_cmp_addr(nsm_addr(nsm), sap))
return nsm;
return NULL;
}

-static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
+static struct nsm_handle *nsm_lookup_priv(const struct list_head *nsm_handles,
+ const struct nsm_private *priv)
{
struct nsm_handle *nsm;

- list_for_each_entry(nsm, &nsm_handles, sm_link)
+ list_for_each_entry(nsm, nsm_handles, sm_link)
if (memcmp(nsm->sm_priv.data, priv->data,
sizeof(priv->data)) == 0)
return nsm;
@@ -350,6 +351,7 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,

/**
* nsm_get_handle - Find or create a cached nsm_handle
+ * @net: network namespace
* @sap: pointer to socket address of handle to find
* @salen: length of socket address
* @hostname: pointer to C string containing hostname to find
@@ -362,11 +364,13 @@ static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
* @hostname cannot be found in the handle cache. Returns NULL if
* an error occurs.
*/
-struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
+struct nsm_handle *nsm_get_handle(const struct net *net,
+ const struct sockaddr *sap,
const size_t salen, const char *hostname,
const size_t hostname_len)
{
struct nsm_handle *cached, *new = NULL;
+ struct lockd_net *ln = net_generic(net, lockd_net_id);

if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
if (printk_ratelimit()) {
@@ -381,9 +385,10 @@ retry:
spin_lock(&nsm_lock);

if (nsm_use_hostnames && hostname != NULL)
- cached = nsm_lookup_hostname(hostname, hostname_len);
+ cached = nsm_lookup_hostname(&ln->nsm_handles,
+ hostname, hostname_len);
else
- cached = nsm_lookup_addr(sap);
+ cached = nsm_lookup_addr(&ln->nsm_handles, sap);

if (cached != NULL) {
atomic_inc(&cached->sm_count);
@@ -397,7 +402,7 @@ retry:
}

if (new != NULL) {
- list_add(&new->sm_link, &nsm_handles);
+ list_add(&new->sm_link, &ln->nsm_handles);
spin_unlock(&nsm_lock);
dprintk("lockd: created nsm_handle for %s (%s)\n",
new->sm_name, new->sm_addrbuf);
@@ -414,19 +419,22 @@ retry:

/**
* nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
+ * @net: network namespace
* @info: pointer to NLMPROC_SM_NOTIFY arguments
*
* Returns a matching nsm_handle if found in the nsm cache. The returned
* nsm_handle's reference count is bumped. Otherwise returns NULL if some
* error occurred.
*/
-struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
+struct nsm_handle *nsm_reboot_lookup(const struct net *net,
+ const struct nlm_reboot *info)
{
struct nsm_handle *cached;
+ struct lockd_net *ln = net_generic(net, lockd_net_id);

spin_lock(&nsm_lock);

- cached = nsm_lookup_priv(&info->priv);
+ cached = nsm_lookup_priv(&ln->nsm_handles, &info->priv);
if (unlikely(cached == NULL)) {
spin_unlock(&nsm_lock);
dprintk("lockd: never saw rebooted peer '%.*s' before\n",
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 5010b55628b4..414da99744e9 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -16,6 +16,7 @@ struct lockd_net {
spinlock_t nsm_clnt_lock;
unsigned int nsm_users;
struct rpc_clnt *nsm_clnt;
+ struct list_head nsm_handles;
};

extern int lockd_net_id;
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 59a53f664005..bb1ad4df024d 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -583,6 +583,7 @@ static int lockd_init_net(struct net *net)
INIT_DELAYED_WORK(&ln->grace_period_end, grace_ender);
INIT_LIST_HEAD(&ln->grace_list);
spin_lock_init(&ln->nsm_clnt_lock);
+ INIT_LIST_HEAD(&ln->nsm_handles);
return 0;
}

diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index b147d1ae71fd..09c576f26c7b 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -421,7 +421,7 @@ nlm4svc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
return rpc_system_err;
}

- nlm_host_rebooted(argp);
+ nlm_host_rebooted(SVC_NET(rqstp), argp);
return rpc_success;
}

diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 21171f0c6477..fb26b9f522e7 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -464,7 +464,7 @@ nlmsvc_proc_sm_notify(struct svc_rqst *rqstp, struct nlm_reboot *argp,
return rpc_system_err;
}

- nlm_host_rebooted(argp);
+ nlm_host_rebooted(SVC_NET(rqstp), argp);
return rpc_success;
}

diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index dcaad79f54ed..0adf073f13b3 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -236,7 +236,8 @@ void nlm_rebind_host(struct nlm_host *);
struct nlm_host * nlm_get_host(struct nlm_host *);
void nlm_shutdown_hosts(void);
void nlm_shutdown_hosts_net(struct net *net);
-void nlm_host_rebooted(const struct nlm_reboot *);
+void nlm_host_rebooted(const struct net *net,
+ const struct nlm_reboot *);

/*
* Host monitoring
@@ -244,11 +245,13 @@ void nlm_host_rebooted(const struct nlm_reboot *);
int nsm_monitor(const struct nlm_host *host);
void nsm_unmonitor(const struct nlm_host *host);

-struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
+struct nsm_handle *nsm_get_handle(const struct net *net,
+ const struct sockaddr *sap,
const size_t salen,
const char *hostname,
const size_t hostname_len);
-struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info);
+struct nsm_handle *nsm_reboot_lookup(const struct net *net,
+ const struct nlm_reboot *info);
void nsm_release(struct nsm_handle *nsm);

/*
--
2.7.2

Next message: Roman Kagan: "Re: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization"
Previous message: Jiri Slaby: "[PATCH 3.12 050/116] devres: fix a for loop bounds check"
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