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2024-02-19 890e1df1bec891d9203724541e81f8fbe5183388

 kernel/fs/nsfs.c
..
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@@ -1,7 +1,9 @@
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 // SPDX-License-Identifier: GPL-2.0
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 #include <linux/mount.h>
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+#include <linux/pseudo_fs.h>
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 #include <linux/file.h>
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 #include <linux/fs.h>
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+#include <linux/proc_fs.h>
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 #include <linux/proc_ns.h>
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 #include <linux/magic.h>
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 #include <linux/ktime.h>
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@@ -9,6 +11,8 @@
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 #include <linux/user_namespace.h>
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 #include <linux/nsfs.h>
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 #include <linux/uaccess.h>
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+
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+#include "internal.h"
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 static struct vfsmount *nsfs_mnt;
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@@ -51,7 +55,7 @@
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 	ns->ops->put(ns);
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 }
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-static void *__ns_get_path(struct path *path, struct ns_common *ns)
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+static int __ns_get_path(struct path *path, struct ns_common *ns)
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 {
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 	struct vfsmount *mnt = nsfs_mnt;
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 	struct dentry *dentry;
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@@ -70,13 +74,13 @@
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 got_it:
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 	path->mnt = mntget(mnt);
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 	path->dentry = dentry;
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-	return NULL;
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+	return 0;
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 slow:
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 	rcu_read_unlock();
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 	inode = new_inode_pseudo(mnt->mnt_sb);
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 	if (!inode) {
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 		ns->ops->put(ns);
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-		return ERR_PTR(-ENOMEM);
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+		return -ENOMEM;
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 	}
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 	inode->i_ino = ns->inum;
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 	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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@@ -88,7 +92,7 @@
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 	dentry = d_alloc_anon(mnt->mnt_sb);
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 	if (!dentry) {
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 		iput(inode);
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-		return ERR_PTR(-ENOMEM);
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+		return -ENOMEM;
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 	}
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 	d_instantiate(dentry, inode);
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 	dentry->d_fsdata = (void *)ns->ops;
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@@ -97,25 +101,23 @@
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 		d_delete(dentry);	/* make sure ->d_prune() does nothing */
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 		dput(dentry);
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 		cpu_relax();
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-		return ERR_PTR(-EAGAIN);
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+		return -EAGAIN;
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 	}
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 	goto got_it;
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 }
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-void *ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
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+int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
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 		     void *private_data)
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 {
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-	struct ns_common *ns;
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-	void *ret;
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+	int ret;
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-again:
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-	ns = ns_get_cb(private_data);
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-	if (!ns)
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-		return ERR_PTR(-ENOENT);
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+	do {
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+		struct ns_common *ns = ns_get_cb(private_data);
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+		if (!ns)
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+			return -ENOENT;
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+		ret = __ns_get_path(path, ns);
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+	} while (ret == -EAGAIN);
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-	ret = __ns_get_path(path, ns);
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-	if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN)
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-		goto again;
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 	return ret;
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 }
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..
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@@ -131,7 +133,7 @@
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 	return args->ns_ops->get(args->task);
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 }
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-void *ns_get_path(struct path *path, struct task_struct *task,
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+int ns_get_path(struct path *path, struct task_struct *task,
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 		  const struct proc_ns_operations *ns_ops)
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 {
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 	struct ns_get_path_task_args args = {
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@@ -147,14 +149,14 @@
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 {
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 	struct path path = {};
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 	struct file *f;
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-	void *err;
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+	int err;
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 	int fd;
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 	fd = get_unused_fd_flags(O_CLOEXEC);
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 	if (fd < 0)
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 		return fd;
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-	while (1) {
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+	do {
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 		struct ns_common *relative;
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 		relative = get_ns(ns);
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@@ -164,13 +166,11 @@
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 		}
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 		err = __ns_get_path(&path, relative);
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-		if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN)
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-			continue;
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-		break;
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-	}
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-	if (IS_ERR(err)) {
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+	} while (err == -EAGAIN);
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+
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+	if (err) {
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 		put_unused_fd(fd);
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-		return PTR_ERR(err);
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+		return err;
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 	}
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 	f = dentry_open(&path, O_RDONLY, current_cred());
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@@ -229,6 +229,11 @@
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 	return res;
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 }
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+bool proc_ns_file(const struct file *file)
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+{
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+	return file->f_op == &ns_file_operations;
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+}
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+
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 struct file *proc_ns_fget(int fd)
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 {
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 	struct file *file;
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@@ -247,6 +252,20 @@
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 	return ERR_PTR(-EINVAL);
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 }
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+/**
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+ * ns_match() - Returns true if current namespace matches dev/ino provided.
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+ * @ns_common: current ns
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+ * @dev: dev_t from nsfs that will be matched against current nsfs
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+ * @ino: ino_t from nsfs that will be matched against current nsfs
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+ *
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+ * Return: true if dev and ino matches the current nsfs.
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+ */
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+bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
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+{
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+	return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
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+}
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+
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+
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 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
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 {
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 	struct inode *inode = d_inode(dentry);
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@@ -261,15 +280,20 @@
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 	.evict_inode = nsfs_evict,
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 	.show_path = nsfs_show_path,
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 };
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-static struct dentry *nsfs_mount(struct file_system_type *fs_type,
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-			int flags, const char *dev_name, void *data)
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+
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+static int nsfs_init_fs_context(struct fs_context *fc)
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 {
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-	return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
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-			&ns_dentry_operations, NSFS_MAGIC);
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+	struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
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+	if (!ctx)
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+		return -ENOMEM;
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+	ctx->ops = &nsfs_ops;
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+	ctx->dops = &ns_dentry_operations;
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+	return 0;
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 }
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+
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 static struct file_system_type nsfs = {
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 	.name = "nsfs",
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-	.mount = nsfs_mount,
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+	.init_fs_context = nsfs_init_fs_context,
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 	.kill_sb = kill_anon_super,
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 };
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