As noted in the previous patch, the NFSv4 client mount code currently
has several limitations. If the mount path contains symlinks, or
referrals, or even if it just contains a '..', then the client code in
nfs4_path_walk() will fail with an error.
This patch replaces the nfs4_path_walk()-based lookup with a helper
function that sets up a private namespace to represent the namespace on the
server, then uses the ordinary VFS and NFS path lookup code to walk down the
mount path in that namespace.
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfs/super.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++-------
1 files changed, 157 insertions(+), 21 deletions(-)
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index b798ed1..8da7e59 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -42,6 +42,8 @@
#include <linux/smp_lock.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
+#include <linux/mnt_namespace.h>
+#include <linux/namei.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/inet.h>
@@ -270,10 +272,14 @@ static const struct super_operations nfs_sops = {
#ifdef CONFIG_NFS_V4
static int nfs4_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
+static int nfs4_remote_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static int nfs4_xdev_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static int nfs4_referral_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
+static int nfs4_remote_referral_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs4_kill_super(struct super_block *sb);
static struct file_system_type nfs4_fs_type = {
@@ -284,6 +290,14 @@ static struct file_system_type nfs4_fs_type = {
.fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};
+static struct file_system_type nfs4_remote_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "nfs4",
+ .get_sb = nfs4_remote_get_sb,
+ .kill_sb = nfs4_kill_super,
+ .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
struct file_system_type nfs4_xdev_fs_type = {
.owner = THIS_MODULE,
.name = "nfs4",
@@ -292,6 +306,14 @@ struct file_system_type nfs4_xdev_fs_type = {
.fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
};
+static struct file_system_type nfs4_remote_referral_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "nfs4",
+ .get_sb = nfs4_remote_referral_get_sb,
+ .kill_sb = nfs4_kill_super,
+ .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+};
+
struct file_system_type nfs4_referral_fs_type = {
.owner = THIS_MODULE,
.name = "nfs4",
@@ -2422,12 +2444,12 @@ out_no_client_address:
}
/*
- * Get the superblock for an NFS4 mountpoint
+ * Get the superblock for the NFS4 root partition
*/
-static int nfs4_get_sb(struct file_system_type *fs_type,
+static int nfs4_remote_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
- struct nfs_parsed_mount_data *data;
+ struct nfs_parsed_mount_data *data = raw_data;
struct super_block *s;
struct nfs_server *server;
struct nfs_fh *mntfh;
@@ -2438,18 +2460,12 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
};
int error = -ENOMEM;
- data = kzalloc(sizeof(*data), GFP_KERNEL);
mntfh = kzalloc(sizeof(*mntfh), GFP_KERNEL);
if (data == NULL || mntfh == NULL)
goto out_free_fh;
security_init_mnt_opts(&data->lsm_opts);
- /* Validate the mount data */
- error = nfs4_validate_mount_data(raw_data, data, dev_name);
- if (error < 0)
- goto out;
-
/* Get a volume representation */
server = nfs4_create_server(data, mntfh);
if (IS_ERR(server)) {
@@ -2462,7 +2478,7 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
compare_super = NULL;
/* Get a superblock - note that we may end up sharing one that already exists */
- s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
+ s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
if (IS_ERR(s)) {
error = PTR_ERR(s);
goto out_free;
@@ -2499,14 +2515,9 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
error = 0;
out:
- kfree(data->client_address);
- kfree(data->nfs_server.export_path);
- kfree(data->nfs_server.hostname);
- kfree(data->fscache_uniq);
security_free_mnt_opts(&data->lsm_opts);
out_free_fh:
kfree(mntfh);
- kfree(data);
return error;
out_free:
@@ -2520,6 +2531,102 @@ error_splat_super:
goto out;
}
+static struct vfsmount *nfs_do_root_mount(struct file_system_type *fs_type,
+ int flags, void *data, const char *hostname)
+{
+ struct vfsmount *root_mnt;
+ char *root_devname;
+ size_t len;
+
+ len = strlen(hostname) + 3;
+ root_devname = kmalloc(len, GFP_KERNEL);
+ if (root_devname == NULL)
+ return ERR_PTR(-ENOMEM);
+ snprintf(root_devname, len, "%s:/", hostname);
+ root_mnt = vfs_kern_mount(fs_type, flags, root_devname, data);
+ kfree(root_devname);
+ return root_mnt;
+}
+
+static int nfs_follow_remote_path(struct vfsmount *root_mnt,
+ const char *export_path, struct vfsmount *mnt_target)
+{
+ struct mnt_namespace *ns_private;
+ struct nameidata nd;
+ struct super_block *s;
+ int ret;
+
+ ns_private = create_mnt_ns(root_mnt);
+ ret = PTR_ERR(ns_private);
+ if (IS_ERR(ns_private))
+ goto out_mntput;
+
+ ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
+ export_path, LOOKUP_FOLLOW, &nd);
+
+ put_mnt_ns(ns_private);
+
+ if (ret != 0)
+ goto out_err;
+
+ s = nd.path.mnt->mnt_sb;
+ atomic_inc(&s->s_active);
+ mnt_target->mnt_sb = s;
+ mnt_target->mnt_root = dget(nd.path.dentry);
+
+ path_put(&nd.path);
+ down_write(&s->s_umount);
+ return 0;
+out_mntput:
+ mntput(root_mnt);
+out_err:
+ return ret;
+}
+
+/*
+ * Get the superblock for an NFS4 mountpoint
+ */
+static int nfs4_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
+{
+ struct nfs_parsed_mount_data *data;
+ char *export_path;
+ struct vfsmount *root_mnt;
+ int error = -ENOMEM;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (data == NULL)
+ goto out_free_data;
+
+ /* Validate the mount data */
+ error = nfs4_validate_mount_data(raw_data, data, dev_name);
+ if (error < 0)
+ goto out;
+
+ export_path = data->nfs_server.export_path;
+ data->nfs_server.export_path = "/";
+ root_mnt = nfs_do_root_mount(&nfs4_remote_fs_type, flags, data,
+ data->nfs_server.hostname);
+ data->nfs_server.export_path = export_path;
+
+ error = PTR_ERR(root_mnt);
+ if (IS_ERR(root_mnt))
+ goto out;
+
+ error = nfs_follow_remote_path(root_mnt, export_path, mnt);
+
+out:
+ kfree(data->client_address);
+ kfree(data->nfs_server.export_path);
+ kfree(data->nfs_server.hostname);
+ kfree(data->fscache_uniq);
+out_free_data:
+ kfree(data);
+ dprintk("<-- nfs4_get_sb() = %d%s\n", error,
+ error != 0 ? " [error]" : "");
+ return error;
+}
+
static void nfs4_kill_super(struct super_block *sb)
{
struct nfs_server *server = NFS_SB(sb);
@@ -2615,12 +2722,9 @@ error_splat_super:
return error;
}
-/*
- * Create an NFS4 server record on referral traversal
- */
-static int nfs4_referral_get_sb(struct file_system_type *fs_type, int flags,
- const char *dev_name, void *raw_data,
- struct vfsmount *mnt)
+static int nfs4_remote_referral_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data,
+ struct vfsmount *mnt)
{
struct nfs_clone_mount *data = raw_data;
struct super_block *s;
@@ -2699,4 +2803,36 @@ error_splat_super:
return error;
}
+/*
+ * Create an NFS4 server record on referral traversal
+ */
+static int nfs4_referral_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data,
+ struct vfsmount *mnt)
+{
+ struct nfs_clone_mount *data = raw_data;
+ char *export_path;
+ struct vfsmount *root_mnt;
+ int error;
+
+ dprintk("--> nfs4_referral_get_sb()\n");
+
+ export_path = data->mnt_path;
+ data->mnt_path = "/";
+
+ root_mnt = nfs_do_root_mount(&nfs4_remote_referral_fs_type,
+ flags, data, data->hostname);
+ data->mnt_path = export_path;
+
+ error = PTR_ERR(root_mnt);
+ if (IS_ERR(root_mnt))
+ goto out;
+
+ error = nfs_follow_remote_path(root_mnt, export_path, mnt);
+out:
+ dprintk("<-- nfs4_referral_get_sb() = %d%s\n", error,
+ error != 0 ? " [error]" : "");
+ return error;
+}
+
#endif /* CONFIG_NFS_V4 */
--
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