NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes

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: stable@vger.kernel.org
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 1d09289c8f0e370dd3f45a17a7c077246b23d7da..180d1ec9c32ed511f3ce33f72088902ad050fffc 100644 (file)
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1205,7 +1205,7 @@ static const struct file_operations nfs_server_list_fops = {
        .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_volume_list_fops = {
        .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_volume_list_fops = {
  */
 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 inode *inode, struct file *file)
  */
 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(struct seq_file *m, loff_t *_pos)
  */
 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 seq_file *p, void *v, loff_t *pos)
  */
 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 seq_file *p, void *v)
 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 seq_file *m, void *v)
  */
 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 inode *inode, struct file *file)
  */
 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(struct seq_file *m, loff_t *_pos)
  */
 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 seq_file *p, void *v, loff_t *pos)
  */
 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 seq_file *m, void *v)
        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 seq_file *m, void *v)
        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;

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 9927913c97c2eb80909d7e4a06f033046f1bcdc5..a732cbbd4e809e54121b1a80be293a41fa21251f 100644 (file)
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1840,11 +1840,12 @@ 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);
 }
 

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index f415cbf9f6c3f99a208005f39c7ce206ee2b1587..2d2ebdfb0723cce549b0ea64a75925d3f3c0fdfd 100644 (file)
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -195,7 +195,16 @@ extern struct rpc_clnt *nfs4_find_or_create_ds_client(struct nfs_client *,
 #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;

diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index 8ee1fab832686ed068468c5de8b12789af8a6371..ef221fb8a18301d05282aa36a3c99ba2b1288b7c 100644 (file)
--- 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;