1 files changed, 689 insertions, 0 deletions

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
new file mode 100644
index 000000000..11fade89c
--- /dev/null
+++ b/kernel/bpf/inode.c
@@ -0,0 +1,689 @@
+/*
+ * Minimal file system backend for holding eBPF maps and programs,
+ * used by bpf(2) object pinning.
+ *
+ * Authors:
+ *
+ *	Daniel Borkmann <daniel@iogearbox.net>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/magic.h>
+#include <linux/major.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include <linux/kdev_t.h>
+#include <linux/parser.h>
+#include <linux/filter.h>
+#include <linux/bpf.h>
+#include <linux/bpf_trace.h>
+
+enum bpf_type {
+	BPF_TYPE_UNSPEC	= 0,
+	BPF_TYPE_PROG,
+	BPF_TYPE_MAP,
+};
+
+static void *bpf_any_get(void *raw, enum bpf_type type)
+{
+	switch (type) {
+	case BPF_TYPE_PROG:
+		raw = bpf_prog_inc(raw);
+		break;
+	case BPF_TYPE_MAP:
+		raw = bpf_map_inc(raw, true);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return raw;
+}
+
+static void bpf_any_put(void *raw, enum bpf_type type)
+{
+	switch (type) {
+	case BPF_TYPE_PROG:
+		bpf_prog_put(raw);
+		break;
+	case BPF_TYPE_MAP:
+		bpf_map_put_with_uref(raw);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+}
+
+static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type)
+{
+	void *raw;
+
+	*type = BPF_TYPE_MAP;
+	raw = bpf_map_get_with_uref(ufd);
+	if (IS_ERR(raw)) {
+		*type = BPF_TYPE_PROG;
+		raw = bpf_prog_get(ufd);
+	}
+
+	return raw;
+}
+
+static const struct inode_operations bpf_dir_iops;
+
+static const struct inode_operations bpf_prog_iops = { };
+static const struct inode_operations bpf_map_iops  = { };
+
+static struct inode *bpf_get_inode(struct super_block *sb,
+				   const struct inode *dir,
+				   umode_t mode)
+{
+	struct inode *inode;
+
+	switch (mode & S_IFMT) {
+	case S_IFDIR:
+	case S_IFREG:
+	case S_IFLNK:
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	inode = new_inode(sb);
+	if (!inode)
+		return ERR_PTR(-ENOSPC);
+
+	inode->i_ino = get_next_ino();
+	inode->i_atime = current_time(inode);
+	inode->i_mtime = inode->i_atime;
+	inode->i_ctime = inode->i_atime;
+
+	inode_init_owner(inode, dir, mode);
+
+	return inode;
+}
+
+static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
+{
+	*type = BPF_TYPE_UNSPEC;
+	if (inode->i_op == &bpf_prog_iops)
+		*type = BPF_TYPE_PROG;
+	else if (inode->i_op == &bpf_map_iops)
+		*type = BPF_TYPE_MAP;
+	else
+		return -EACCES;
+
+	return 0;
+}
+
+static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode,
+				struct inode *dir)
+{
+	d_instantiate(dentry, inode);
+	dget(dentry);
+
+	dir->i_mtime = current_time(dir);
+	dir->i_ctime = dir->i_mtime;
+}
+
+static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode;
+
+	inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFDIR);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	inode->i_op = &bpf_dir_iops;
+	inode->i_fop = &simple_dir_operations;
+
+	inc_nlink(inode);
+	inc_nlink(dir);
+
+	bpf_dentry_finalize(dentry, inode, dir);
+	return 0;
+}
+
+struct map_iter {
+	void *key;
+	bool done;
+};
+
+static struct map_iter *map_iter(struct seq_file *m)
+{
+	return m->private;
+}
+
+static struct bpf_map *seq_file_to_map(struct seq_file *m)
+{
+	return file_inode(m->file)->i_private;
+}
+
+static void map_iter_free(struct map_iter *iter)
+{
+	if (iter) {
+		kfree(iter->key);
+		kfree(iter);
+	}
+}
+
+static struct map_iter *map_iter_alloc(struct bpf_map *map)
+{
+	struct map_iter *iter;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN);
+	if (!iter)
+		goto error;
+
+	iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN);
+	if (!iter->key)
+		goto error;
+
+	return iter;
+
+error:
+	map_iter_free(iter);
+	return NULL;
+}
+
+static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct bpf_map *map = seq_file_to_map(m);
+	void *key = map_iter(m)->key;
+	void *prev_key;
+
+	(*pos)++;
+	if (map_iter(m)->done)
+		return NULL;
+
+	if (unlikely(v == SEQ_START_TOKEN))
+		prev_key = NULL;
+	else
+		prev_key = key;
+
+	rcu_read_lock();
+	if (map->ops->map_get_next_key(map, prev_key, key)) {
+		map_iter(m)->done = true;
+		key = NULL;
+	}
+	rcu_read_unlock();
+	return key;
+}
+
+static void *map_seq_start(struct seq_file *m, loff_t *pos)
+{
+	if (map_iter(m)->done)
+		return NULL;
+
+	return *pos ? map_iter(m)->key : SEQ_START_TOKEN;
+}
+
+static void map_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static int map_seq_show(struct seq_file *m, void *v)
+{
+	struct bpf_map *map = seq_file_to_map(m);
+	void *key = map_iter(m)->key;
+
+	if (unlikely(v == SEQ_START_TOKEN)) {
+		seq_puts(m, "# WARNING!! The output is for debug purpose only\n");
+		seq_puts(m, "# WARNING!! The output format will change\n");
+	} else {
+		map->ops->map_seq_show_elem(map, key, m);
+	}
+
+	return 0;
+}
+
+static const struct seq_operations bpffs_map_seq_ops = {
+	.start	= map_seq_start,
+	.next	= map_seq_next,
+	.show	= map_seq_show,
+	.stop	= map_seq_stop,
+};
+
+static int bpffs_map_open(struct inode *inode, struct file *file)
+{
+	struct bpf_map *map = inode->i_private;
+	struct map_iter *iter;
+	struct seq_file *m;
+	int err;
+
+	iter = map_iter_alloc(map);
+	if (!iter)
+		return -ENOMEM;
+
+	err = seq_open(file, &bpffs_map_seq_ops);
+	if (err) {
+		map_iter_free(iter);
+		return err;
+	}
+
+	m = file->private_data;
+	m->private = iter;
+
+	return 0;
+}
+
+static int bpffs_map_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = file->private_data;
+
+	map_iter_free(map_iter(m));
+
+	return seq_release(inode, file);
+}
+
+/* bpffs_map_fops should only implement the basic
+ * read operation for a BPF map.  The purpose is to
+ * provide a simple user intuitive way to do
+ * "cat bpffs/pathto/a-pinned-map".
+ *
+ * Other operations (e.g. write, lookup...) should be realized by
+ * the userspace tools (e.g. bpftool) through the
+ * BPF_OBJ_GET_INFO_BY_FD and the map's lookup/update
+ * interface.
+ */
+static const struct file_operations bpffs_map_fops = {
+	.open		= bpffs_map_open,
+	.read		= seq_read,
+	.release	= bpffs_map_release,
+};
+
+static int bpffs_obj_open(struct inode *inode, struct file *file)
+{
+	return -EIO;
+}
+
+static const struct file_operations bpffs_obj_fops = {
+	.open		= bpffs_obj_open,
+};
+
+static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
+			 const struct inode_operations *iops,
+			 const struct file_operations *fops)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	inode->i_op = iops;
+	inode->i_fop = fops;
+	inode->i_private = raw;
+
+	bpf_dentry_finalize(dentry, inode, dir);
+	return 0;
+}
+
+static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg)
+{
+	return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops,
+			     &bpffs_obj_fops);
+}
+
+static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
+{
+	struct bpf_map *map = arg;
+
+	return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops,
+			     bpf_map_support_seq_show(map) ?
+			     &bpffs_map_fops : &bpffs_obj_fops);
+}
+
+static struct dentry *
+bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags)
+{
+	/* Dots in names (e.g. "/sys/fs/bpf/foo.bar") are reserved for future
+	 * extensions.
+	 */
+	if (strchr(dentry->d_name.name, '.'))
+		return ERR_PTR(-EPERM);
+
+	return simple_lookup(dir, dentry, flags);
+}
+
+static int bpf_symlink(struct inode *dir, struct dentry *dentry,
+		       const char *target)
+{
+	char *link = kstrdup(target, GFP_USER | __GFP_NOWARN);
+	struct inode *inode;
+
+	if (!link)
+		return -ENOMEM;
+
+	inode = bpf_get_inode(dir->i_sb, dir, S_IRWXUGO | S_IFLNK);
+	if (IS_ERR(inode)) {
+		kfree(link);
+		return PTR_ERR(inode);
+	}
+
+	inode->i_op = &simple_symlink_inode_operations;
+	inode->i_link = link;
+
+	bpf_dentry_finalize(dentry, inode, dir);
+	return 0;
+}
+
+static const struct inode_operations bpf_dir_iops = {
+	.lookup		= bpf_lookup,
+	.mkdir		= bpf_mkdir,
+	.symlink	= bpf_symlink,
+	.rmdir		= simple_rmdir,
+	.rename		= simple_rename,
+	.link		= simple_link,
+	.unlink		= simple_unlink,
+};
+
+static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
+			  enum bpf_type type)
+{
+	struct dentry *dentry;
+	struct inode *dir;
+	struct path path;
+	umode_t mode;
+	int ret;
+
+	dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
+
+	ret = security_path_mknod(&path, dentry, mode, 0);
+	if (ret)
+		goto out;
+
+	dir = d_inode(path.dentry);
+	if (dir->i_op != &bpf_dir_iops) {
+		ret = -EPERM;
+		goto out;
+	}
+
+	switch (type) {
+	case BPF_TYPE_PROG:
+		ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw);
+		break;
+	case BPF_TYPE_MAP:
+		ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw);
+		break;
+	default:
+		ret = -EPERM;
+	}
+out:
+	done_path_create(&path, dentry);
+	return ret;
+}
+
+int bpf_obj_pin_user(u32 ufd, const char __user *pathname)
+{
+	struct filename *pname;
+	enum bpf_type type;
+	void *raw;
+	int ret;
+
+	pname = getname(pathname);
+	if (IS_ERR(pname))
+		return PTR_ERR(pname);
+
+	raw = bpf_fd_probe_obj(ufd, &type);
+	if (IS_ERR(raw)) {
+		ret = PTR_ERR(raw);
+		goto out;
+	}
+
+	ret = bpf_obj_do_pin(pname, raw, type);
+	if (ret != 0)
+		bpf_any_put(raw, type);
+out:
+	putname(pname);
+	return ret;
+}
+
+static void *bpf_obj_do_get(const struct filename *pathname,
+			    enum bpf_type *type, int flags)
+{
+	struct inode *inode;
+	struct path path;
+	void *raw;
+	int ret;
+
+	ret = kern_path(pathname->name, LOOKUP_FOLLOW, &path);
+	if (ret)
+		return ERR_PTR(ret);
+
+	inode = d_backing_inode(path.dentry);
+	ret = inode_permission(inode, ACC_MODE(flags));
+	if (ret)
+		goto out;
+
+	ret = bpf_inode_type(inode, type);
+	if (ret)
+		goto out;
+
+	raw = bpf_any_get(inode->i_private, *type);
+	if (!IS_ERR(raw))
+		touch_atime(&path);
+
+	path_put(&path);
+	return raw;
+out:
+	path_put(&path);
+	return ERR_PTR(ret);
+}
+
+int bpf_obj_get_user(const char __user *pathname, int flags)
+{
+	enum bpf_type type = BPF_TYPE_UNSPEC;
+	struct filename *pname;
+	int ret = -ENOENT;
+	int f_flags;
+	void *raw;
+
+	f_flags = bpf_get_file_flag(flags);
+	if (f_flags < 0)
+		return f_flags;
+
+	pname = getname(pathname);
+	if (IS_ERR(pname))
+		return PTR_ERR(pname);
+
+	raw = bpf_obj_do_get(pname, &type, f_flags);
+	if (IS_ERR(raw)) {
+		ret = PTR_ERR(raw);
+		goto out;
+	}
+
+	if (type == BPF_TYPE_PROG)
+		ret = bpf_prog_new_fd(raw);
+	else if (type == BPF_TYPE_MAP)
+		ret = bpf_map_new_fd(raw, f_flags);
+	else
+		goto out;
+
+	if (ret < 0)
+		bpf_any_put(raw, type);
+out:
+	putname(pname);
+	return ret;
+}
+
+static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type type)
+{
+	struct bpf_prog *prog;
+	int ret = inode_permission(inode, MAY_READ);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (inode->i_op == &bpf_map_iops)
+		return ERR_PTR(-EINVAL);
+	if (inode->i_op != &bpf_prog_iops)
+		return ERR_PTR(-EACCES);
+
+	prog = inode->i_private;
+
+	ret = security_bpf_prog(prog);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	if (!bpf_prog_get_ok(prog, &type, false))
+		return ERR_PTR(-EINVAL);
+
+	return bpf_prog_inc(prog);
+}
+
+struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type)
+{
+	struct bpf_prog *prog;
+	struct path path;
+	int ret = kern_path(name, LOOKUP_FOLLOW, &path);
+	if (ret)
+		return ERR_PTR(ret);
+	prog = __get_prog_inode(d_backing_inode(path.dentry), type);
+	if (!IS_ERR(prog))
+		touch_atime(&path);
+	path_put(&path);
+	return prog;
+}
+EXPORT_SYMBOL(bpf_prog_get_type_path);
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int bpf_show_options(struct seq_file *m, struct dentry *root)
+{
+	umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX;
+
+	if (mode != S_IRWXUGO)
+		seq_printf(m, ",mode=%o", mode);
+	return 0;
+}
+
+static void bpf_destroy_inode_deferred(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	enum bpf_type type;
+
+	if (S_ISLNK(inode->i_mode))
+		kfree(inode->i_link);
+	if (!bpf_inode_type(inode, &type))
+		bpf_any_put(inode->i_private, type);
+	free_inode_nonrcu(inode);
+}
+
+static void bpf_destroy_inode(struct inode *inode)
+{
+	call_rcu(&inode->i_rcu, bpf_destroy_inode_deferred);
+}
+
+static const struct super_operations bpf_super_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+	.show_options	= bpf_show_options,
+	.destroy_inode	= bpf_destroy_inode,
+};
+
+enum {
+	OPT_MODE,
+	OPT_ERR,
+};
+
+static const match_table_t bpf_mount_tokens = {
+	{ OPT_MODE, "mode=%o" },
+	{ OPT_ERR, NULL },
+};
+
+struct bpf_mount_opts {
+	umode_t mode;
+};
+
+static int bpf_parse_options(char *data, struct bpf_mount_opts *opts)
+{
+	substring_t args[MAX_OPT_ARGS];
+	int option, token;
+	char *ptr;
+
+	opts->mode = S_IRWXUGO;
+
+	while ((ptr = strsep(&data, ",")) != NULL) {
+		if (!*ptr)
+			continue;
+
+		token = match_token(ptr, bpf_mount_tokens, args);
+		switch (token) {
+		case OPT_MODE:
+			if (match_octal(&args[0], &option))
+				return -EINVAL;
+			opts->mode = option & S_IALLUGO;
+			break;
+		/* We might like to report bad mount options here, but
+		 * traditionally we've ignored all mount options, so we'd
+		 * better continue to ignore non-existing options for bpf.
+		 */
+		}
+	}
+
+	return 0;
+}
+
+static int bpf_fill_super(struct super_block *sb, void *data, int silent)
+{
+	static const struct tree_descr bpf_rfiles[] = { { "" } };
+	struct bpf_mount_opts opts;
+	struct inode *inode;
+	int ret;
+
+	ret = bpf_parse_options(data, &opts);
+	if (ret)
+		return ret;
+
+	ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
+	if (ret)
+		return ret;
+
+	sb->s_op = &bpf_super_ops;
+
+	inode = sb->s_root->d_inode;
+	inode->i_op = &bpf_dir_iops;
+	inode->i_mode &= ~S_IALLUGO;
+	inode->i_mode |= S_ISVTX | opts.mode;
+
+	return 0;
+}
+
+static struct dentry *bpf_mount(struct file_system_type *type, int flags,
+				const char *dev_name, void *data)
+{
+	return mount_nodev(type, flags, data, bpf_fill_super);
+}
+
+static struct file_system_type bpf_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "bpf",
+	.mount		= bpf_mount,
+	.kill_sb	= kill_litter_super,
+};
+
+static int __init bpf_init(void)
+{
+	int ret;
+
+	ret = sysfs_create_mount_point(fs_kobj, "bpf");
+	if (ret)
+		return ret;
+
+	ret = register_filesystem(&bpf_fs_type);
+	if (ret)
+		sysfs_remove_mount_point(fs_kobj, "bpf");
+
+	return ret;
+}
+fs_initcall(bpf_init);