From 65b38851a17472d31fec9019fc3a55b0802dab88 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 31 Jul 2014 04:35:20 -0700 Subject: 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 Cc: Stanislav Kinsbursky Signed-off-by: "Eric W. Biederman" --- fs/nfs/client.c | 95 +++++++++++++++++++++++++++++++++------------------------ 1 file changed, 55 insertions(+), 40 deletions(-) (limited to 'fs/nfs/client.c') diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 1d09289..180d1ec 100644 --- 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; 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