[PATCH 3.14 83/88] NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes

Greg Kroah-Hartman
2014-09-03T23:23:37Z

From: "Eric W. Biederman" <ebiederm@xmission.com>

commit 65b38851a17472d31fec9019fc3a55b0802dab88 upstream.

The usage of pid_ns->child_reaper->nsproxy->net_ns in
nfs_server_list_open and nfs_client_list_open is not safe.

/proc for a pid namespace can remain mounted after the all of the
process in that pid namespace have exited. There are also times
before the initial process in a pid namespace has started or after the
initial process in a pid namespace has exited where
pid_ns->child_reaper can be NULL or stale. Making the idiom
pid_ns->child_reaper->nsproxy a double whammy of problems.

Luckily all that needs to happen is to move /proc/fs/nfsfs/servers and
/proc/fs/nfsfs/volumes under /proc/net to /proc/net/nfsfs/servers and
/proc/net/nfsfs/volumes and add a symlink from the original location,
and to use seq_open_net as it has been designed.

Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/client.c | 95 +++++++++++++++++++++++++++++++-----------------------
fs/nfs/inode.c | 3 +
fs/nfs/internal.h | 9 +++++
fs/nfs/netns.h | 3 +
4 files changed, 69 insertions(+), 41 deletions(-)

--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1205,7 +1205,7 @@ static const struct file_operations nfs_
.open = nfs_server_list_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release,
+ .release = seq_release_net,
.owner = THIS_MODULE,
};

@@ -1226,7 +1226,7 @@ static const struct file_operations nfs_
.open = nfs_volume_list_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = seq_release,
+ .release = seq_release_net,
.owner = THIS_MODULE,
};

@@ -1236,19 +1236,8 @@ static const struct file_operations nfs_
*/
static int nfs_server_list_open(struct inode *inode, struct file *file)
{
- struct seq_file *m;
- int ret;
- struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info;
- struct net *net = pid_ns->child_reaper->nsproxy->net_ns;
-
- ret = seq_open(file, &nfs_server_list_ops);
- if (ret < 0)
- return ret;
-
- m = file->private_data;
- m->private = net;
-
- return 0;
+ return seq_open_net(inode, file, &nfs_server_list_ops,
+ sizeof(struct seq_net_private));
}

/*
@@ -1256,7 +1245,7 @@ static int nfs_server_list_open(struct i
*/
static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
{
- struct nfs_net *nn = net_generic(m->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);

/* lock the list against modification */
spin_lock(&nn->nfs_client_lock);
@@ -1268,7 +1257,7 @@ static void *nfs_server_list_start(struc
*/
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
{
- struct nfs_net *nn = net_generic(p->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);

return seq_list_next(v, &nn->nfs_client_list, pos);
}
@@ -1278,7 +1267,7 @@ static void *nfs_server_list_next(struct
*/
static void nfs_server_list_stop(struct seq_file *p, void *v)
{
- struct nfs_net *nn = net_generic(p->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);

spin_unlock(&nn->nfs_client_lock);
}
@@ -1289,7 +1278,7 @@ static void nfs_server_list_stop(struct
static int nfs_server_list_show(struct seq_file *m, void *v)
{
struct nfs_client *clp;
- struct nfs_net *nn = net_generic(m->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);

/* display header on line 1 */
if (v == &nn->nfs_client_list) {
@@ -1321,19 +1310,8 @@ static int nfs_server_list_show(struct s
*/
static int nfs_volume_list_open(struct inode *inode, struct file *file)
{
- struct seq_file *m;
- int ret;
- struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info;
- struct net *net = pid_ns->child_reaper->nsproxy->net_ns;
-
- ret = seq_open(file, &nfs_volume_list_ops);
- if (ret < 0)
- return ret;
-
- m = file->private_data;
- m->private = net;
-
- return 0;
+ return seq_open_net(inode, file, &nfs_server_list_ops,
+ sizeof(struct seq_net_private));
}

/*
@@ -1341,7 +1319,7 @@ static int nfs_volume_list_open(struct i
*/
static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
{
- struct nfs_net *nn = net_generic(m->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);

/* lock the list against modification */
spin_lock(&nn->nfs_client_lock);
@@ -1353,7 +1331,7 @@ static void *nfs_volume_list_start(struc
*/
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
{
- struct nfs_net *nn = net_generic(p->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);

return seq_list_next(v, &nn->nfs_volume_list, pos);
}
@@ -1363,7 +1341,7 @@ static void *nfs_volume_list_next(struct
*/
static void nfs_volume_list_stop(struct seq_file *p, void *v)
{
- struct nfs_net *nn = net_generic(p->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id);

spin_unlock(&nn->nfs_client_lock);
}
@@ -1376,7 +1354,7 @@ static int nfs_volume_list_show(struct s
struct nfs_server *server;
struct nfs_client *clp;
char dev[8], fsid[17];
- struct nfs_net *nn = net_generic(m->private, nfs_net_id);
+ struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id);

/* display header on line 1 */
if (v == &nn->nfs_volume_list) {
@@ -1407,6 +1385,45 @@ static int nfs_volume_list_show(struct s
return 0;
}

+int nfs_fs_proc_net_init(struct net *net)
+{
+ struct nfs_net *nn = net_generic(net, nfs_net_id);
+ struct proc_dir_entry *p;
+
+ nn->proc_nfsfs = proc_net_mkdir(net, "nfsfs", net->proc_net);
+ if (!nn->proc_nfsfs)
+ goto error_0;
+
+ /* a file of servers with which we're dealing */
+ p = proc_create("servers", S_IFREG|S_IRUGO,
+ nn->proc_nfsfs, &nfs_server_list_fops);
+ if (!p)
+ goto error_1;
+
+ /* a file of volumes that we have mounted */
+ p = proc_create("volumes", S_IFREG|S_IRUGO,
+ nn->proc_nfsfs, &nfs_volume_list_fops);
+ if (!p)
+ goto error_2;
+ return 0;
+
+error_2:
+ remove_proc_entry("servers", nn->proc_nfsfs);
+error_1:
+ remove_proc_entry("fs/nfsfs", NULL);
+error_0:
+ return -ENOMEM;
+}
+
+void nfs_fs_proc_net_exit(struct net *net)
+{
+ struct nfs_net *nn = net_generic(net, nfs_net_id);
+
+ remove_proc_entry("volumes", nn->proc_nfsfs);
+ remove_proc_entry("servers", nn->proc_nfsfs);
+ remove_proc_entry("fs/nfsfs", NULL);
+}
+
/*
* initialise the /proc/fs/nfsfs/ directory
*/
@@ -1419,14 +1436,12 @@ int __init nfs_fs_proc_init(void)
goto error_0;

/* a file of servers with which we're dealing */
- p = proc_create("servers", S_IFREG|S_IRUGO,
- proc_fs_nfs, &nfs_server_list_fops);
+ p = proc_symlink("servers", proc_fs_nfs, "../../net/nfsfs/servers");
if (!p)
goto error_1;

/* a file of volumes that we have mounted */
- p = proc_create("volumes", S_IFREG|S_IRUGO,
- proc_fs_nfs, &nfs_volume_list_fops);
+ p = proc_symlink("volumes", proc_fs_nfs, "../../net/nfsfs/volumes");
if (!p)
goto error_2;
return 0;
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1814,11 +1814,12 @@ EXPORT_SYMBOL_GPL(nfs_net_id);
static int nfs_net_init(struct net *net)
{
nfs_clients_init(net);
- return 0;
+ return nfs_fs_proc_net_init(net);
}

static void nfs_net_exit(struct net *net)
{
+ nfs_fs_proc_net_exit(net);
nfs_cleanup_cb_ident_idr(net);
}

--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -195,7 +195,16 @@ extern struct rpc_clnt *nfs4_find_or_cre
#ifdef CONFIG_PROC_FS
extern int __init nfs_fs_proc_init(void);
extern void nfs_fs_proc_exit(void);
+extern int nfs_fs_proc_net_init(struct net *net);
+extern void nfs_fs_proc_net_exit(struct net *net);
#else
+static inline int nfs_fs_proc_net_init(struct net *net)
+{
+ return 0;
+}
+static inline void nfs_fs_proc_net_exit(struct net *net)
+{
+}
static inline int nfs_fs_proc_init(void)
{
return 0;
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -29,6 +29,9 @@ struct nfs_net {
#endif
spinlock_t nfs_client_lock;
struct timespec boot_time;
+#ifdef CONFIG_PROC_FS
+ struct proc_dir_entry *proc_nfsfs;
+#endif
};

extern int nfs_net_id;